Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND SYSTEMS FOR ELECTROMAGNETIC PROTECTION WITH
PERSISTENT SELF MONITORING AND CYBERSECURE LOCAL AND REMOTE
STATUS REPORT
REFERENCE TO RELATED APPLICATIONS
This application claims the priority of non-provisional patent 17/521,369
filed on
November 8, 2021, titled Method and Systems for Protection of Electrical
Multiports from
Electromagnetic Pulse Using Impedance Matching and Low Insertion Loss Design,
which claims
the priority art of non-provisional patent application 17/148,168 filed on
January 13, 2021, titled
Method and Systems for Detection and Protection From Electromagnetic Pulse
Events Using
Hardware Implemented Artificial Intelligence (now US Pat. No 11,714,483),
which claims the
priority art of non-provisional patent application 16/925,600, filed July 10,
2020 titled Method for
Detecting an Isolating an Electromagnetic Pulse for Protection of a Monitored
Infrastructure (now
US Pat. No. 10,938,204), which claims the priority of non-provisional patent
application
16/597,427 filed October 9, 2019, (now US Pat. No. 10,742,025), titled System
and Method for
Detecting an Isolating an Electromagnetic Pulse for Protection of a Monitored
Infrastructure,
which claims the priority of non-provisional patent application 16/240,897
filed January 7, 2019
(now US Patent 10,530,151), titled System and Method For Suppressing
Electromagnetic Pulse-
Induced Electrical System Surges, which claims the benefit of provisional
patent application U.S.
Serial No. 62/615159 filed January 9, 2018 titled System and Method For
Suppressing
Electromagnetic Pulse-Induced Electrical System Surges, all of which are
incorporated in their
entirety herein by reference.
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BACKGROUND OF THE INVENTION
This invention relates generally to persistent monitoring and detecting an
electromagnetic
pulse (EMP) and mitigating the impending effects of said pulse to prevent
damage from the
impinging surge energy to an infrastructure such as an electrical grid or its
components for
generating, transmitting, distributing, and using of electrical power at
commercial facility, or the
like as shown in Fig. 1.
An electromagnetic pulse, also sometimes called a transient electromagnetic
disturbance,
is a short burst of electromagnetic energy. The waveform of an EMP in time
domain describes
how the amplitude of the ultrashort pulse changes over the time and correlates
to the intensity of
the EM field. The real pulses tend to be quite complicated, so their
simplified descriptions are
typically characterized by:
= The type of radiated (with different polarization) or conducted
electromagnetic
energy.
= Pulse waveform: shape (rise and fall time), pulse width at half maximum
(PWHM),
duration, and peak amplitude.
= The range or spectrum of frequencies present and the power spectrum
distribution.
Any EMP is associated with electromagnetic interference (EMI) with respect to
electrical
systems, devices, and components. The degree of interference depends on the
level of
electromagnetic susceptibility of the system of interest and the immunity of
its electrical and
electronic components. The level of effect is related to the intensity and the
duration of the EMP.
Based on the generated frequency content and its distribution, an EMP is
classified as
"narrowband", "wideband" and "ultrawideband" electromagnetic source. The
frequency spectrum
of the pulse and its waveform in time domain are interrelated analytically via
the Fourier transform
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and other mathematical transformations for joint time-frequency representation
(wavelet analysis,
spectrograms, etc.). An EMP typically contains energy at many frequencies from
direct current
(DC) to some upper limit depending on the source. Withing the bandwidth, there
could be multiple
spectral peaks with high magnitudes. In general, the shorter the pulse (which
also implies a short
rise time) the broader the spread of energy over a range of frequencies. The
commonly used first-
order approximation is fh = 0.35 / Tr, where (Hz) is the upper high frequency
range and Tr
(seconds) is the rise time of the pulse from 10% to 90% of its peak amplitude.
An electromagnetic pulse, or EMP, can be generally characterized as a short
duration burst
of electromagnetic radiation generated by either natural events or man-made
sources. Some
examples for natural sources include the atmospheric lightning strikes, the
Solar flares (intense
eruptions of electromagnetic radiation in the Sun's atmosphere), which are
often followed by
Coronal Mass Ejection (CME), and solar particle events (proton acceleration),
producing an
immense amount of energy (usually estimated to 1020 Joules, with significant
activity pushing that
number up to 1025 Joules). Solar wind, Solar flares and CME are commonly known
as Space
weather events that produce Geomagnetic Disturbance (GMD) and associated
currents with high
magnitude and extremely low frequencies. Man produced EMP examples include an
EMP
associated with a nuclear blast and EMPs generated using Directed Energy
Weapons (DEW),
which are also known as Intentional Electromagnetic Interference (IEMI).
In this document, the focus is on the hazardous effects of EMP associated with
the
detonation of a nuclear weapon and the possible methods for protection from
the generated
electromagnetic fields. In the special case of nuclear detonation at high
altitude above the Earth's
surface, the EMP is known as nuclear (NEMP), high-altitude (HEMP), or High-
altitude Nuclear
EMP (HNEMP). Without loss of generality, Fig. 2 illustrates an electromagnetic
pulse generation
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by high-altitude nuclear blast resulting in a HEMP. A source region EMP
(SREMP) is a burst of
energy similar to HEMP but created when a nuclear weapon detonates at lower
altitudes within
the atmosphere.
In general, the interactions of the high-energy gamma rays with the atoms in
the
atmosphere produce electrons (known as Compton electrons) which interact with
the Geo-
magnetic field resulting in a large region, which extends above the Earth's
surface producing EM
field with a Poynting vector from the source region towards the Earth's
surface, as illustrated in
Fig. 2 and Fig. 3. The field generated by a high-altitude EMP (HEMP) has a
global impact and
over the horizon extended effects. Its intensity changes along a North-South
central line below the
nuclear blast, indicated with GZ (Ground Zero) in Fig. 2. The pictograph of
the nuclear burst and
the Electromagnetic Field (EMF) Poynting vector direction with respect to the
observer's location
is shown in Fig. 3. The intensity of the pulse varies by location (latitude)
due to the Geo-magnetic
field distribution. Some additional relevant factors will be discussed further
while the specific
details of the related physical phenomena are beyond the scope of this
application. Please note that
the figures from Fig. 2 to Fig. 10 are included to illustrate and supplement
the description of the
physical phenomena associated with HEMPs, their modeling, simulation, and
understanding.
The terms "EMP" or "HEMP" as used herein refer to the electromagnetic pulse
generated
by a nuclear blast at high altitude, a directed energy weapon (DEW) source for
high-power
electromagnetic energy, other devices for intentional EMI (IEMI), natural
Space weather events
within the Solar system, supernova explosion, and other cosmic phenomenon
resulting in
Geomagnetic Disturbance (GMD) and large scale EMP effects. While the natural
events associated
with the Solar activity are monitored and occur with an 11-year periodic
cycle, the HEMP is
typically classified as "low-probability, high-impact event" initiated by a
nuclear explosion at high
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altitude. The DEW and IEMI have targeted and localized effects posing a threat
that have to be
considered and countermeasures need to be deployed at critical infrastructure
systems.
An EMP event can induce voltages and corresponding currents into different
electrical
systems. The magnitude of the induced voltage/current depends on the coupling
of the EM field
with the system (its susceptibility) and the characteristics of the EM wave
(direction, polarization,
frequency content, and others). The transmission lines of the electric power
distribution grid, as
well as the electrical systems of localized mini-grids, renewable energy
systems, communication
lines, commercial buildings, electrical wiring of buildings, and even vehicle
electrical systems (on
land, air, and sea) are readily exposed to the EMT'. Fig. 4 illustrates the
coupling of the EM energy
into a transmission line located at height h above the ground. The image
displays a few key
relations of the electric field (E) and magnetic field (B) using the Half-
space Earth model. The
image is from "The Early-time (El) HEMP and its impact on the US Power Grid"
report, written
in 2010 by Savage et al, Metatech Corporation, and provides an excellent
analysis of the physical
phenomena associated with the HEMP.
Unless monitored, detected, isolated, or suppressed and redirected, the
unwanted induced
current and over-voltage surges from an EMP can damage or destroy components
within the
electrical systems in the area of impact, which is global in the case of HEMP.
The result is
diminishing the operability of the electrical grid, subsystems and rendering
them unusable until
repaired or replaced. As seen in Fig. 2, due to its origin, a HEMP will induce
effects in a very large
area. Similarly, it is understood that a massive solar ejection (CME) reaching
the Earth imposes
GMD which have damaging effects and failure of components within the
electrical grid and the
electrical infrastructure components with induced over-currents, resulting,
for example, in
overheating and damaging of high-voltage transformers.
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Unlike the electromagnetic radiation or pulse associated with common natural
phenomena
(lighting strikes, transmission lines overvoltage from load switching,
harmonics, etc.), the HEMP
comprises of more complex time and frequency domain characteristics.
Historically, the HEMP is
described with several stages in time following the nuclear blast. They are
also known as HEMP
phases or pulses of varying waveform (magnitude, duration, frequency content,
etc.). Therefore,
the HEMP is more accurately described as a complex, electromagnetic multi-
pulse event - a
sequence of three primary components defined by the International
Electrotechnical Commission
(IEC) as El, E2, and E3 sequential phases of the high-altitude EMP (HEMP). The
characteristics
of these phases (pulses) of HEMP are further described in this application.
The relative electric
field strength of the time sequence is displayed in Fig. 5a and Fig 5b using
logarithmic scales for
E (V/m) vs Time (s). Some of the commonly used analytical expressions for the
HEMP El, E2,
and E3 waveforms are given in Fig. 6, which presents the waveforms, and the
model parameter
values.
Starting in the 1960s, multiple waveform descriptions have been developed in
order to
model the associated hazardous effects. A series of standards related to the
description of the
associated waveforms are known as IEC 77C Standards. The evolution of the
unclassified
standards with respect to the El HEMP environment can be seen in the Table in
Fig. 7, which
displays the changes of the waveform parameters of the unclassified HEMP El
environment
Standards. Some additional details of the associated pulse waveform
characteristics are given in
the Table in Fig. 8.
As can be seen from the Table in Fig. 7, the most common analytical
expressions for El
HEMP are the Difference of Double Exponential (DEXP) and the Quotient of
Exponentials
(QEXP). The plots of DEXP and QEXP in time domain and their respective
spectral distribution
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in frequency domain are presented in Fig. 9. The DEXP and the QEXP are most
frequently used
analytical expressions for modeling. Additional analytical expressions have
also been developed.
Their description is beyond the scope of this application.
The damage to electrical and electronic devices is determined by the amount of
energy that
is transferred to the devices in the given electromagnetic environment.
Potentially, all electrical or
electronic equipment has a level of susceptibility: from no effect to upset,
malfunction and
permanent damage under the electromagnetic radiation of sufficient intensity.
The plots in Fig. 10
illustrate the power spectrum density (V/m-Hz) associated with a HEMP El, an
atmospheric
lightning, and IEMI (high-power electromagnetic radiation, high-intensity RF).
The level of system vulnerability is dependent on the intensity of the EMF and
the coupling
of the external fields to the electrical circuits and the immunity
characteristics of circuits
components. A temporary malfunction (or upset) can occur when an
electromagnetic field induces
current(s) and voltage(s) in the operating system electronic circuits at
levels that are comparable
to the normal operational rating characteristics. Regardless of the EMP source
and its
characteristics (power, frequency, mode), two principal coupling modes are
possible, and the
relevant standards relate to assessing how much radiated power is coupled into
a target system: (1)
"Front door" coupling (FDC), and (2) "Back door" coupling (BDC). The FDC is
typically
observed when the power radiated from an IEMI source is directly coupled into
the electronic
systems with an antenna. The antenna/transmitter subsystem is designed to
receive and transmit
RF signals, and thus provides an efficient path for the energy flow from the
electromagnetic
environment to enter the equipment and cause damage especially when the
antenna's bandwidth
is withing the frequency range of the IEMI source (in band coupling). As seen
in Fig. 10, the
HEMP El has a very broad bandwidth.
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The BDC occurs when the electromagnetic field of the environment propagates
and
couples through the existing gaps, small apertures, electrical wiring and
interconnecting cables,
connections to the power mains, communication cables, network and telephone
copper wires,
unshielded sections, and others. The BDC can generally be described as a wide-
range interference
at specific narrow-band susceptibility characteristics because of existing
apertures and modes of
coupling to cables_
Since the impinging EMP field has a broad frequency spectrum and a high field
strength,
the antenna coupling must be considered with the in band and out of band
interference. Any
electrically penetrating conducting structures, power lines, and communication
cables are
inadvertent, unintended, or parasitic antennae that collect EMP energy and
allow its entry into a
building, a device, or an enclosure. The electrical wires of the grid can be
considered as an
unintended pathway and as an imperfect antenna connected to the upstream and
downstream
components of the electrical network. The power transmission lines are
susceptible to broadband
frequencies, including the lower frequency (long wavelength) coupling due to
their long length.
Additional factors influence the level of coupling and interference: wave
direction and
polarization, geolocation, ground surface conductivity, height of the wires
above ground,
shielding, and others_ With their long length, the electrical transmission
lines are some of the
structures especially susceptible to the E3 HEMP, as further described below.
The internal wiring
of building, including data and communication centers, are also susceptible to
EMF and would
couple directly to the radiated field if the building is without a proper
shielding. The indirect
coupling to communication lines due to proximity of power distribution cables
is also present_
Protection of electrical and electronic systems from radiated coupling of EM
field is
achieved by shielding of equipment with a conductive enclosure. In some cases,
the whole building
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can be a shielding structure, commonly known as a Faraday cage shielding.
Because input and
output cables for power and communications must be present, special methods
are employed to
lower and limit the propagation of the induced transients via these wired
connections and their
conduit openings.
As described in the referenced related prior patents, one possible way to
mitigate the effects
of EMP is to detect in real time the occurrence of an event and trigger means
to absorb and redirect
the excessive energy surge, or disconnect the protected systems by isolating
them physically from
long cables, wires, antennas, etc. An additional protection method is to equip
the electrical and
electronic systems with means that prevent the excessive magnitude of voltage
and current and
limit, shunt, absorb, and redirect the energy of the EMP. Generally, these
devices are known as
surge suppressors and arrestors. Most commercially available surge suppressing
devices are design
and built to offer protection to lightning with micro-seconds response times.
This is not sufficient
for protection from the HEMP El and IEMI waveforms with nano-second and even
sub nano-
second rise times. The referenced related applications provide novel solutions
for mitigation of the
El, E2, and E3 components of an EMP. Specifically, to protect from the
damaging effects of EMP,
the protection measures must be persistently engaged without interfering with
the normal operation
of the protected system. That implies implementing protection with threshold
settings outside the
normal operating range and, yet, limiting within close values above the
working range.
An illustration is presented in Fig. 11 for a metal oxide varistor (MOV) and a
gas discharge
tube (GDT) surge suppressing devices. In this simple example, the normal
operating range of the
protected device is below the limiting level labeled as the "DC breakdown
voltage". The three
superimposed plots illustrate the transient waveform without a surge
suppression, the limiting
threshold level response of the MOV, and the typical crowbar shunting response
of the GDT. When
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GDT devices are used for surge protection, they are usually referred as surge
arrestors. In designing
practical surge protecting circuits, nonlinear devices such as MOVs, GDTs, and
semiconductor
devices (thyristor, avalanche-type Zener diode, etc.) are combined with
additional components:
inductors and capacitors filters, thermal and current fuses, and others. In
September 2006, the
Underwriter Laboratories published the revised version of "UL Standard for
Safety for Surge
Protective Devices, UL 1449", and replaced the commonly used transient voltage
surge suppressor
(TVSS) by surge protective devices (SPDs). In this application, the SPD
acronym is used for surge
protection device and may include different implementation technologies: MOVs,
TVSs, GDTs,
glass gas discharge tube (GGDT), and other emerging surge limiting and
shunting components.
There are multiple type of surge suppressing devices based on different
technologies and
materials. The devices can and are implemented in different combinations and
configurations.
Some implementations are described in the referenced related applications
including novel
solutions providing enhanced EMP protection. The main goal is fast and
effective response to an
EMP event with a system-wide protection. In general, this includes common mode
and differential
mode protection. For example, for an AC distribution circuit, this implies
line protection for each
phase to phase, phase to neutral, and phase to ground line pairs. Typically,
the breakdown voltage
of the protective components is selected 20% or more above the normal
operating voltage and
depends on the specific implementation and the environment surges. The
appropriate response
must be triggered to provide adequate protection for the monitored
infrastructure. There are
multiple considerations for the design and implementation of surge protection.
Due to the
complexity of the HEMP with the different characteristics of the El, E2, and
E3, a hybrid
combinations of multiple surge suppression components are utilized to provide
a fast response to
HEMP El and an extended energy mitigation capacity to HEMP E2 and E3.
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In developing surge protection circuits, the designer must look after two
important aspects,
namely: (1) the inserted surge protection stages should not alter the normal
operation of the
protected system; (2) components used for surge absorption, diversion, or
attenuation should
withstand the surges safely. Reliability of the surge protection system is a
very important concern,
since in practical circumstances, if a very high-magnitude voltage surge
enters the system, it might
damage the surge arrestor in a non-safe manner. The potential fire hazard was
addressed with the
development of MOVs devices with an embedded thermal fuse and an additional
terminal to be
used for "open fuse" indication. Because of the variety of circuit designs
with non-linear
components for surge protection, additional measures are necessary to provide
a proper SPD
operation and a failsafe assurance.
In general, the available surge protection devices (SPD) incorporate some form
of system
status indicators. Usually, this includes light emitting diodes (LEDs) andJor
an audible indicator.
The implemented state indication is limited to a local annunciation and is
intended for use by a
present human observer. This presents certain limitations given the usual
place of installation of
the SPDs. Respectively, a direct line of sight is necessary for the front
panel LED indicators. In
addition, an audible status indication is not sufficient when multiple devices
are installed in closed
proximity. While a cluster installation is not common for small commercial and
residential
installations, it presents a deficiency for proper status monitoring of the
protective devices in more
complex infrastructure deployments. Nevertheless, it is preferable and, in
some application,
necessary to be able to monitor the status of the installed SPDs remotely with
a convenient display
and automatically without any additional efforts.
The present invention recognizes the described deficiencies and provides
solutions for
implementing protection of electrical and electronic infrastructure from EMT'
using method and
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systems for persistent self-monitoring with local and remote status report.
The design of the
protection device includes LED indication for each protected line, thermal
overload, ground
disconnect, and an overall alarm. In addition, every abnormal condition is
indicated with an audible
alarm. Because a surge may result in power lost due to the fuse line
disconnect, the present
invention uses an embedded power supply based on combined AC/DC converters
providing DC
supply for the annunciator circuits even in the case of a phase line power
loss. Furthermore, the
current application includes a DC power storage subcircuit based on a
supercapacitor. In the
situation of complete AC power loss on all input AC power lines, the
supercapacitor provides local
and/or remote notification for the "alarm" status.
The current application provide solution for a secure status communication to
a remote
central display location with capabilities to monitor the status of hundreds
and even thousand of
SPDs. Given the complexity and scale of modern critical infrastructure, the
proposed solution
provides installation flexibility for multiple distributed and clustered SPDs.
Given the constantly
present cybersecurity threats, the current application offers a solution using
one-directional
communication channel for remote status display.
Some aspects on remote EMP detection notification using fiberoptic is
addressed in
referenced patent application 16/925,600 filed July 10, 2020 (now US Pat. No.
10,93,204), titled
"Method for Detecting an Isolating an Electromagnetic Pulse for Protection of
a Monitored
Infrastructure". It is used to communicate the detection of a HEMP El and to
trigger an additional
protective action, The present application provides solution for more complete
SPD status
indication in real time with local display and status report to remote
location. The remote link is
with one-way communication for an ultimate cybersecure implementation.
Additional features of
the novel method and systems will be described further.
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The present invention includes a solution for transient search protection of a
monitored
system which is enhanced with persistent self-monitoring and cybersecure local
and remote status
reporting in real time. Complex critical infrastructure facilities such as an
electrical substation or
a power generation plant, requires the installation of SPDs at multiple points
and with multiline
configurations. The need to use multiple SPD in clustered installations with
the ability for remote
status display at a centralize location requires the capability for remote
monitoring of the status
without introducing or compromising the overall cybersecurity of the
infrastructure. Pertinent
electrical design parameters for EMP protection are combined with additional
status self-
monitoring and reporting in real time. The detailed description for each
method is beyond the scope
of this application. EMP protection implementations are described in the
referenced related
applications including novel solutions providing enhanced EMP protection.
The main purpose of the current application is to provide protection to the
monitored
system (infrastructure, in general) with a real time persistent status
monitoring of the SPDs from
a central portal in a cybersecure manner (hacker-proof deployment). The
protective system based
on the present invention detects and protects the connected systems by
limiting, shunting, and
absorbing the energy of the surge transient pulses before they can reach the
input ports of the
protected infrastructure. The present invention recognizes that the teaching
of the referenced
related patent applications can be extended and used to "time stamp" the
occurrence of a HEMP
or an IEMI event (or other high-voltage transient pulses) and to report the
detection to a remote
portal for real time status display and historical events log. This "time
stamp" of the event is device
and line specific due to the unique identification of each SPD. The historical
profile can be used
for preventive maintenance, an improved reliability, and overall enhanced
resilience of the
protected infrastructure.
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SUMMARY OF THE INVENTION
Embodiments of the invention are defined by the claims below and not solely by
this
summary. A high-level overview of various aspects of the invention are given
here for that reason,
to provide an overview of the disclosure, and to introduce a selection of
concepts that are further
described in the Detailed Description section below. This summary is not
intended to identify key
features or essential features of the claimed subject matter, nor is it
intended to be used as an aid
in isolation to determine the scope of the claimed subject matter. In brief,
this disclosure describes
a novel and enhanced system for monitoring, detecting, and responding to
electromagnetic pulse
induced electrical surges associated with a multi-pulse radiation complex
generated by the
detonation of a nuclear weapon (NEMP) or IEMI. Among other things, the
application describes
a system and method for EMP protection using a real time self-monitoring with
local display and
a cybersecure remote report communication for the status of the protected
infrastructure and the
protection device.
In one aspect, the system and method for suppressing electromagnetic pulse-
induced surges
on an electrical system comprises a plurality of voltage and current magnitude
limiters and shunts
placed between, and in electrical communication with, a plurality of power
lines in an electrical
system, such that common mode and differential mode voltages on electrical
power lines that
exceeds a predetermined level are limited and shunted by at least one of the
plurality of surge
protection components (SPCs) to prevent the voltage amplitude from exceeding a
predefined
desired level.
In another aspect, the response time of the plurality of shunts and the
allowable voltage
amplitude level of the SPCs are selected and combined to achieve a predefined
desired response
time and protection level capacity to react to and mitigate the El, E2, and E3
components of a
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complex multi-pulse event generated by detonation of a nuclear weapon at high
altitude (HEMP).
In a similar aspect, the response time and the voltage limiting and energy
handling capacity of the
plurality of shunts responds to intentional electromagnetic interference
(IEMI).
In a further aspect, the system and method protect line-to-line, line-to-
neutral, neutral to
ground, and line-to-ground arrangements of an electrical system's power lines,
as well as
combinations and sub-combinations thereof forming an SPD based on plurality of
SPCs.
In alternative embodiments, the system and method of the present invention are
configured
to protect single-phase and three-phase land-based electrical systems, in
further alternative
embodiments the system and method are configured for use on alternative
electric power
generation systems (solar, wind, fuel cell) and the electrical systems of
vehicles, such as
automobiles, trucks, locomotives, boats, aircraft and other vehicles employing
on-board electrical
systems.
It is understood that the current application solves the limitations and
constraints associated
with the existing SPD that have front panel visual LED and/or audible
indicators to display normal
and fault/alarm status. The system and method according to the present
invention provides
protection to AC and DC power lines with an enhanced self-monitoring status
and local and remote
status indication. The self-monitoring and annunciation are implemented with
analog electronic
circuits and the status conditions are communicated in real time to a remote
location using an
electro-optical channel with controlled directionality. The regular operation
with one-directional
communication provides an inherent cybersecure network configuration for
critical infrastructure
installations with multiple distributed and clustered surge protection
devices. The importance of
the implemented cybersecure remote communication is the provision to deploy
multiple SPDs
within the perimeter of a critical infrastructure and monitor the status of
all protected locations
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including the status of the protected lines and the protecting devices. This
application provides a
solution for distributed installations at large critical infrastructures such
as a power generation
facility (nuclear power plants, electrical grid substation, solar and wind
generation power farms),
a military base, a large datacenter, and an industrial complex. The net result
is an improved EMP
resilience with real time situational awareness for the status of the
protected infrastructure.
More particularly, the present invention provides a solution for protection of
a single-phase
and three-phase AC circuits. The method provides scalable implementations for
different AC and
DC voltage electric lines. Figure 12 presents an overall view of an SPD
installed on a three-phase
electric power line. As can be seen, the SPD consists of multiple surge
protection components
(SPCs) mounted between each phase line (Phl-Ph2, Phl -Ph3, Ph2-Ph3) and
between each phase
line and the neutral line (N), and each phase line and ground (GND). When
necessary and
depending on the location of the ground connection, additional SPC may be
connected between
neutral (N) and ground (GND) lines. For simplicity, a single symbol of a SPC
is used to represent
a single possible type or multiple types of components in different
combinations and
configurations. There are many possible designs of an SPD with respect to the
voltage threshold
limiting levels and shunting capacity of the components, The variety of
implementations are not
the focus of the current application.
Figure 13 is a block-diagram representation of an SPD installed on the
electric power line
powering the protected device. In general, the electric power line can be an
AC or a DC supply
line. The new and important part is the presence of a communication channel
for remote status
report (display) which is shown with the one-directional arrow.
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Figure 14 displays the block-diagram of one possible implementation of a
protection
system based on the present application. In the given example, it is an SPD
with an embedded AC-
DC converter, local status display and remote annunciation display.
Figure 15 illustrates details of the embedded AC-DC converter (DC power
supply) with
block-diagram representation of the DC power distribution, super-capacitor
charging module and
a power switch circuit, which automatically continues to provide DC power when
the input AC
electrical power on all phases is lost or disconnected. The block-diagram in
Figure 16 illustrates
the functional subsystems implemented with analog circuit for self-monitoring
and local display
of the SPD and the power lines. Figure 17 presents an implementation of a
system that includes a
level conversion circuit (LCC) from high voltage to low logical levels that
can be further processed
by a microcontroller and a message generating subsystem with an output optical
communication
channel and a secondary alternative communication channel described further in
the text that
follows. Figure 18 displays details of the system transceiver module for the
optical communication
channel and elements of the remote display modules used to provide a
cybersecure communication
channel .
Figure 19 displays some of the circuit details of the analog sense and local
display
subsystem and will be used to describe further the cybersecure self-monitoring
and remote display
functions of the current application. The annunciation functions for the
system's status conditions
are presented in the table in Figure 20. The expanded status display
functionality includes: 1)
individual line (phase) normal status indication; 2) per line fault condition
indicator which also
triggers an overall alarm; 3) loss of power per line (phase); 4) loss of
connection to electrical
ground; 5) intermittent indication of complete power loss.
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BRIEF DESCRIPTION OF THE DRAWINGS
Illustrative embodiments of the invention are described in detail below with
reference to
the attached drawing figures, where some of the figures (from Fig. 2 to Fig.
10) are related to the
physical phenomena associated with a NEMP, and wherein:
Fig. 1 is a view diagram of an electrical grid segment presenting the
generation,
transmission, distribution, and consumption components which will be part of
the infrastructure
subject of protection by the present invention;
Fig. 2 is an illustration of the formation of the HEMP's source region in the
Earth's
atmosphere and the formation of the HEMP based on the interactions of the high-
energy gamma
rays with the atoms and molecules in the atmosphere and the produced electrons
which interact
with the Geo-magnetic field;
Fig. 3. is a pictograph of the nuclear burst high-altitude location and the
Electromagnetic
Field (EMF) Poynting vector direction with respect to an observer's location;
Fig. 4 is an illustration of the EM wave and its E (electric) and H (magnetic)
vectors in the
plane of incidence at a wire at height h above the Earth's surface with a
finite conductivity and
three associated angles (a, 0, and ty) used for modeling and simulation of the
HEMP coupling to
a transmission line;
Fig. 5a is a plot representation in time domain of the complex high-altitude
electromagnetic
multi-pulse event with a sequence of the three primary phases of the HEMP: El
(Early time), E2
(Intermediate time), and E3 (Late time);
Fig. 5b is a plot representation in frequency domain of the spectral content
and spectral
magnitude of the three primary El, E2, and E3 phases of the HEMP;
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Fig. 6 is a tabulated summary of the commonly used analytical expressions for
the HEMP
El, E2, and E3 waveforms with the model parameter values;
Fig. 7 is a table with the HEMP El waveform parameter values and their changes
as the
models and standards describing the HEMP El environment have evolved;
Fig. 8 is a table with additional HEMP El waveform parameters in time domain,
its energy,
and spectral characteristics;
Fig. 9 is a graphical representation of the most common analytical expressions
for El
HEMP - the Difference of Double Exponential (DEXP) and the Quotient of
Exponentials (QEXP).
The DEXP and QEXP plots in time domain are presented on the left and their
respective spectral
distribution in frequency domain are presented on the right side of the
figure;
Fig. 10 is a graphical comparison of the magnitude and bandwidth of the power
spectrum
densities (Vim-Hz) associated with a HEMP El, an atmospheric lightning, and
different
narrowband and ultrawideband IEMI (high-power electromagnetic radiation, high-
intensity
radiofrequency, etc.);
Fig. 11 is a graphical presentation of three superimposed plots illustrating a
surge transient
waveform, the limiting threshold level response of a metal oxide varistor
(MOV), and the typical
crowbar shunting response of a gas discharge tube (GDT);
Fig. 12 is a schematic of a general case surge protection device (SPD)
installation on a
three-phase electrical power line with surge protection components (SPCs)
connected between
each phase line, each phase line to neutral, and each phase line to ground;
Fig. 13 is a block diagram representation of an SPD with an output
communication channel
installed on the electrical power supply of the protected device;
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Fig. 14 is a block diagram of subsystems and modules of an exemplary
implementation of
an EMP protection system with persistent status monitoring and cybersecure
local and remote
status reporting in real time;
Fig. 15 is a block diagram presentation of the DC power supply subsystem, the
DC
distribution bus, the supercapacitor charging circuit, and the automatic
switch circuit for a backup
DC power when the input AC power is lost;
Fig. 16 it is a block diagram schematic of the analog power lines status
sensors and the
respective front panel local visual displays and sound alarm;
Fig. 17 is a block diagram representation of an example system implementation
based on
the current application that includes a voltage level conversion circuit
(LCC), producing low
logical levels from the high voltage levels, for further processing with a
microcontroller and a
transmitter subsystem with output communication channels;
Fig. 18 is block diagram of the system transceiver module for the optical
communication
channel and elements of the remote display modules used to provide a
cybersecure
communication;
Fig. 19 is a block diagram whit some subcircuit details for analog sensor
implementation
to monitor the electric power lines, the SPCs, and to provide indication on
the local display
subsystem; nd
Fig, 20 is a table with the summary of all possible status conditions and
their respective
visual and sound alarm indications.
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DESCRIPTION OF THE PREFERRED EMBODIMENT
The subject matter of select embodiments of the invention is described with
specificity
herein to meet statutory requirements. But the description itself is not
intended to necessarily limit
the scope of claims. Rather, the claimed subject matter might be embodied in
other ways to include
different components, steps, or combinations thereof similar to the ones
described in this
document, in conjunction with other present or future technologies. Terms
should not be
interpreted as implying any particular order among or between various steps
herein disclosed
unless and except when the order of individual steps is explicitly described.
The terms "about",
"approximately", or other terms of approximation as used herein denote
deviations from the exact
value in the form of changes or deviations that are insignificant to the
function.
Before the present invention regarding a method and systems for detecting and
responding
to an electromagnetic pulse so as to protect a monitored infrastructure can be
described in detail
and in context, a deeper understanding of the characteristics of an EMP, in
general, and HEMP, in
particular, will be discussed in the context of traditional electrical
environments and setups.
As initially presented above, an EMP generated by detonation of a nuclear
weapon at a
high altitude in the atmosphere, comprises a sequence of waveforms due to the
multiple and
complex interactions of the products of the nuclear blast with Earth's
atmosphere and geomagnetic
field. Three phases (pulses of varying duration) are used to
describe/represent the HEMP more
accurately. In this regard, the HEMP is considered a complex, electromagnetic
multi-pulse, usually
described in terms of three primary components defined by the International
Electrotechnical
Commission (IEC) as El, E2, and El The three phases of the HEMP are presented
in Fig. 5a in
time domain and their respective time sequence, individual duration, and
magnitude is presented
in Fig. 5b. The nature of these pulses is described further below.
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The El component of the complex multi-pulse is produced when gamma radiation
from the
nuclear detonation knocks electrons out of the atoms in the upper atmosphere_
The electrons begin
to travel at relativistic speeds (i.e., at more than 90 percent of the speed
of light). In the absence of
a magnetic field, the displaced electrons would produce a large pulse of
electric current in the
upper atmosphere over the entire affected area. However, the Earth's magnetic
field acts on the
electrons to change the direction of electron flow so that it is at a right
angle to the geomagnetic
field. This interaction of the Earth's magnetic field and the downward
electron flow produces a
very brief, but very high magnitude, electromagnetic pulse over the affected
area, which area size
(respectively, radius from point zero under the nuclear explosion) depends on
the altitude of the
nuclear detonation.
The process of gamma rays knocking electrons from the atoms in the mid-
stratosphere
ionizes that region, causing it to become an electrically conductive ionized
layer, that limits and
blocks the further expansion of the electromagnetic signals and causing the
field strength to
saturate at about 50,000 volts per meter (50 kV/m). The field strength of the
El HEMP depends
primarily on the altitude of the detonation of the nuclear device, the yield
and intensity of the
gamma rays produced by the weapon, and the geographic latitude (due to the
changes of the
Geomagnetic field with latitude). The atmospheric conditions, and the
conductivity of the Earth's
surface also play roles. The more detail explanations of the undergoing
physical interactions are
beyond the scope of this document and may be found elsewhere.
The interaction of the very rapidly moving, negatively charged electrons with
the
Geomagnetic field radiates a short duration, intense pulse of electromagnetic
energy. The pulse
typically rises to its peak magnitude in about five nanoseconds (5 ns) and
decays within hundreds
of nanoseconds (200 ns ¨ 500 ns, depending on the intensity level used for
measurement
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threshold). The given values may vary based on location and distant to the
blast point. According
to the most recent IEC standard update, the El pulse has a rise time of 2.5 ns
0.5 ns (from 10%
to 90% amplitude levels of the rising edge of the pulse), reaches peak value
of 50 kV/m in 5 ns,
and has a pulse width at its half maximum of 23 ns 5 ns (Fig. 6, Fig. 7,
Fig. 8, and Fig. 9).
Thus, the El component is a short-duration, intense electromagnetic pulse
capable of
inducing very high amplitude voltages in electrical conductors. That induced
high voltage typically
exceeds the breakdown voltage values of common electrical system components,
such as those
used in electronic and communication equipment, degrading and/or destroying
those components.
Because of the extreme parameters of El pulse, most commonly available
lightning surge
protectors are unable to respond and suppress the transient surges induced
into an electrical system
by a HEMP El pulse. Respectively, new technologies and components with
improved response
characteristics are constantly developed in order to provide an adequate
solution.
The HEMP El component is characterized in multiple regulatory standards. The
first
HEMP related standard was created by Bell Labs in the 1960s. Since then,
revisions have been
made, as can be seen from the Table in Fig. 7. In general, the given parameter
values do not
represent the variations with respect to altitude, geolocation distance,
atmosphere conditions, field
vectors direction, and local Earth surface properties, which impact the
formation, propagation, and
reflection of the EM field. The Table in Fig. 8 gives a better understanding
for the temporal and
energy characteristics of the El phase of the HEMP. There are several HEMP
environment
standards, and some are classified such as DoD-STD-2169. Others are in public
domain, such as
IEC STD 61000, MIL-STD-188-125-1, MIL-STD-461G, and MIL-STD-464C_
Two of the well accepted and used analytical expressions of HEMP are provided
in IEC
61000-2-9 and given for a reference in Fig. 9. The combined HEMP timeline
based on analytical
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expressions is provided in IEC 61000-2-9 and is given in Fig. 10. Unclassified
HEMP standards
characterize the El phase of the EMP by idealized Difference of double
exponentials (DEXP) and
quotient exponential (QEXP) waveforms, as shown in the left side plot in Fig.
9 with the blue solid
line and the red dash-dot line, respectively. The plot on the left side in
Fig. 9 displays the HEMP
El model waveforms in time-domain and their respective spectral content is
presented on the right
plot. The evolution of the El HEMP standards is presented in Fig. 7. The a and
II are the
exponential constants and k is a normalizing constant for the peak amplitude
at the cross section
of the two exponentials. In addition to the DEXP and QEXP, two other
analytical forms have been
developed and presented in the literature: the P-index exponential (PEXP) and
the Complimentary
error function (ERFC). The main reasons for these additional analytic models
are some of the
deficiencies of the first two models. For example, the DEXP model is
discontinuous at t = 0, while
QEXP extends to t = co and has an infinite number of poles in the frequency
domain. Further
details for the model waveforms are presented in the relevant literature and
the referenced related
applications.
The method and devices based on the method described in this invention
application for
EMP surge protection are based on specifications listed in the Military and
Civilian Standards and
are developed accordingly for accurate description of El, E2, and E3 pulse
components of a
HEMP. The standards are used to design the SPDs and to test their performance
and to design,
implement, and evaluate the level of protection of devices built for
mitigation of the effects.
This application recognizes the importance of real time situational awareness
for the
overall status of a protected large scale critical infrastructure. The
application provides solution
with persistent status monitoring and communication to a remote display to
form a centralized
portal for plurality of SPD based on the proposed method. Furthermore, the
communication
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channel is optical and immune to EMI. The default regular operation is based
on a one-directional
communication from the distributed SPDs to the remote display location,
resulting in an ultimate
cybersecure implementation. The real time status reporting provides an
enhanced situational
awareness for the protected critical assets.
The referenced figures describe the physical phenomena associated with the
formation of
a HEMP and the provided solutions for protection from the impact of the HEMP
and IEMI effect
with additional capability for expanding the installation of plurality of SPDs
with capability of
cybersecure networked configuration and situational awareness for the status
of large-scale critical
infrastructure.
Looking to Fig. 1, the different segments of the electrical grid are displayed
as the potential
objects of a HEMP impact and the need for their protection.
Looking to Fig. 2, an instance of EMP wave formation is presented, including
its
atmosphere source region, its spatial distribution and variability with
respect to the source and
observer locations.
Looking to Fig. 3, the 3D spatial orientation of the EMP field direction of
incidence from
the source towards the observer is presented with the EM field Poynting
vector, which is normal
to the EM wave plane of incidence, formed by the orthogonal vectors of the
electric field (E) and
the magnetic field B) components.
Looking to Fig. 4, additional Geospatial relations are presented, which are
used to model,
calculate, and simulate the interactions of the EMP with the target of
interest, which in this case is
a segment of an electrical transmission line with a length L at h height above
a finite conducting
ground surface and terminated at bought ends with impedances Z/ and Z2. While
the pictograph
can be used for calculations, in must be complemented with additional factors
when higher
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precision is required. Even under the ideal assumption of a dipole Geomagnetic
field, there are
variation of the B field along the gamma ray path from the nuclear blast.
However, the conditions
are more complex due to the motion of the Compton electrons and the
nonhomogeneous
Geomagnetic field. Assuming a uniform Geomagnetic field is equivalent to
assuming the Earth
radius is extremely large, or the burst height is very low, which is known as
a source region EMP
(SREMP).
Looking to Fig.5a, the complexity of HEMP is presented in terms of sequence of
three
primary components El, E2, and E3, shown in logarithmic scales of the electric
field intensity
(V/m) and time (sec). Labels indicate the physical phenomena that produce the
pulse waveforms
components. HEMP is more accurately described and presented as a multi-pulse
(multi-phase)
electromagnetic event.
Looking to Fig. 5b, the respective time sequence, relative individual
duration, and
magnitudes of El, E2, and E3 is presented.
Looking to Fig. 6, the analytical expressions and the numerical values of the
parameters
for the waveform models of the HEMP Early time El, Intermediate time E2, and
Late time E3 are
presented.
Looking to Fig. 7, the evolution of the standards for El HEMP environment is
presented
with the time domain values for the waveform analytical models.
Looking to Fig. 8, additional information for the IEC El HEMP waveform
properties is
listed with the associated time domain waveform parameters, spectrum peak
power, total energy
and others.
Looking to Fig. 9, the two most common analytical expressions and waveforms
for HEMP
El are displayed in time domain (left plot) and their spectrum in frequency
domain (right plot).
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Looking to Fig. 10, the superimposed plots of spectral density distributions
are displayed
for an El HEMP, an atmospheric lightning, high-intensity radio-frequency
sources, and intentional
electromagnetic interference (IEMI) sources with wide-band and narrow-band
examples.
Looking to Fig. 11, three superimposed plots are displayed, illustrating a
surge transient
waveform, the limiting threshold level response of a metal oxide varistor
(MOV), and the typical
crowbar shunting response of a gas discharge tube (GDT).
Looking to Fig. 12, a generalized schematic of a surge protection device (SPD)
installation
is presented with plurality of surge protection components (SPCs). An example,
using a three-
phase AC electrical power is displayed. Multiple SPCs are connected between
each phase line
(Phl -Ph2, Phl-Ph3, and Ph2-Ph3), each phase line and neutral (N), and each
phase and ground
(GND). The schematic represents a generalized methodology for differential and
common mode
protection implementation. For clarity, individual SPCs are used to represent
any of the different
type components connected individually or in plurality of components
configurations and
combinations.
Looking to Fig. 13, a block-diagram of an SPD installed on an AC electric
power line is
displayed. As shown, the SPD protects a device powered by the same AC power
line. A wide
arrow indicates an output communication channel to a remote display portal.
Looking to Fig. 14, a high-level block diagram 100 is used to present one
possible
implementation of a surge protection device (SPD) based on the current
application. A protected
device 101 is powered by an AC electric power source 104 with multiple lines
for each phase,
neutral line, and ground line. A surge protection device (SPD) 102 is mounted
on the same electric
power line 104 and has three submodules: plurality of high voltage surge
protection components
(SPCs) and additional high voltage subcircuit components 110, an analog
sensors and display
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(ASD) subsystem 111, and a DC power supply module 112. Analog sensor circuits
of ASD 111
are connected to the AC power lines 104, some of the SPCs of 110, and
additional high voltage
subcircuit components of 110. A dedicated high voltage bus 120 connects all
monitored circuit
points to all respective analog sensors and display indicators of ASD
subsystem 111. A DC power
supply 112 is connected to the input AC power line 104 by a bus 106 and
provides DC voltage to
the ASD 111 via a DC supply line 121, and to a level converter module (LCM)
113 and a digital
controller and communication (DCC) module 114 via a DC power distribution
supply line 122.
The LCM 113 and the DCC module 114 form a subsystem for remote display (SRD)
103.
A high voltage bus 123 connects the ASD subsystem 111 to the LCM 113. A
logical level bus 124
connects the LCM 113 to the DCC module 114. A communication channel 125 is the
physical
connection to a remote location display. A subsystem for remote display (SRD)
103 provides the
cybersecure communication solution for a system based on the current
application for protection
of electrical and electronic infrastructure from EMP with persistent self-
monitoring and remote
status report.
Looking to Fig. 15, submodules of the DC power supply 112 are presented. An AC
to DC
conversion subsystem 130 has an AC-DC convertor section for each input AC
power line 104. All
DC outputs of the AC-DC convertor sections are combined to assure a DC power
when one or
more of the input AC lines lose power or is disconnected (loss of a physical
connection, a thermal
fuse or a current-limiting fuse disconnect). The DC power is distributed to
the rest of the
subsystems via the DC distribution buses 121 and 122, as described previously.
The DC power
line also connects to an auto-transfer switch (ATS) circuit 132 via DC power
bus 13L The ATS
132 connects to a super capacitor module (SCM) 134 via a DC power line 133. As
the name
implies, the SCM 134 has a supercapacitor for energy storage and a charging
circuit. A complete
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loss of power on input AC power lines 104 results in a loss of DC voltage at
the output of the DC
power supply 110, which triggers the ATS 132 to provide power from the SCD 134
via DC power
line 133 and DC power bus 131 to the DC distribution buses 121 and 122.
Looking to Fig, 16, details of the analog sensors and display (ASD) subsystem
111 are
presented with a block diagram. Multiple sections of analog sensor circuits
140 of the ADS
subsystem 111 are connected by a dedicated high voltage bus 120. The details
for the high voltage
sections 140 are described further below. Each high voltage section of 140 is
associated with a
respective subset of the AC power lines 104 and consist of analog circuits
that connect to
monitored SPCs of 110 mounted on the associated AC power lines 104 and any
additional
monitored high voltage circuit components of 110. The analog sensor circuits
140 convert the state
of monitored components to signals transferred via a connecting signal bus 141
to drive visual and
sound indicators of an annunciation display module (ADM) 142. The high voltage
bus 123
connects the annunciation display module (ADM) 142 of the ASD subsystem 111 to
the level
converter module (LCM) 113, as shown in Fig 14.
In the given example, visual annunciators are presented as light emitting
diodes (LEDs)
143 and 144. In this case, the triangular group of LEDs 143 presents three
LEDs each one
positioned in the three corners of the group and associated with each one of
the three phases of a
three-phase AC power line 104 (Phi, Ph2, and Ph3). The center LED in the group
143, is an LED
indicating the normal status (connected) or fault status (loss of connection)
to the ground line of
the AC power supply 104. The LED 144 is an overall alarm status indicator. An
alarm status
indication with LED 144 is combined with an audible alarm by a sound source
145. A complete
loss of AC input power 104, triggers the ATS 132 to provide a DC power to the
annunciation
display module (ADM) 142 via power bus 121 from the super capacitor module
(SCM) 134, as
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shown in Fig. 16. The alarm visual indicator 144 and the alarm sound indicator
145 are
intermittently activated to indicate "AC power loss" status alarm condition
for a prolonged time
period, which depends on the stored energy in the super capacitor module 134.
The DC power
voltage provided to the DC power distribution buses 121 and 122 by the super
capacitor module
(SCM) 134 is lower than the nominal DC power supply voltage and is used to
indicate the "AC
power loss" status alarm condition to the remote display and will be described
further below.
Following commonly used color schema, the normal status is visually presented
with a
green color of the LED indicators, which changes to red in case of a fault
condition. Without any
limitations, additional LED colors may be used to indicate a plurality of
possible conditions. This
is facilitated by the available multicolor LEDs. The number of LEDs may vary,
as necessary, to
present indication for each one of the power lines or specific monitored
condition. The
arrangement of the LEDs is not critical and, in general, is implementation
driven. For example, a
single-phase AC power supply has two lines (L1 and L2), one neutral line (N),
and one ground
line (GND) and may use two LEDs for the AC lines, one LED for the ground line
connection
status, and one LED for an overall alarm indicator. Color legends may be
included in the SPD's
user manual or displayed on the SPD's label. Currently, different liquid
crystal displays, LED, and
organic LED display components are available and, without any limitations, may
be used in place
of the individual LEDs 143 and 144.
Looking to Fig. 17, a block diagram is presented with details of the subsystem
for remote
display (SRD) 103 that provides a cybersecure communication solution. The
subsystems of the
level converter module (LCM) 113 and the digital controller and communication
(DCC) module
114 are displayed. A DC power supply to the subsystems is provided by the DC
power supply bus
122. The level converter module (LCM) 113 has two subsystems: a high voltage
levels sensor 150
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and a high voltage to low logical level converter 151. The high voltage bus
123 connects the input
of the LCM 113 to the high voltage level signals at the output interface of
the annunciation display
module (ADM) 142. The level sensor subsystem 150 of the LCM 113 monitors and
measures
voltage peak and RMS values of the high voltage bus 123 to provide an auto
scale factor to the
high voltage to low logical level converter 151. Converted voltage levels at
the output of converter
151 are sent to a microcontroller subsystem 152 via the interface logical
level bus 124. The
microcontroller subsystem 152 is one of the subsystems of the digital
controller and
communication (DCC) 114 and performs digital processing and communication
control. The
microcontroller subsystem 152 interfaces to a digital communication
transceiver 153 via an
interface 154 and a secondary alternative transmitter 156 via an interface
155. The digital
communication transceiver 153 communicates with a remote location using the
communication
channel 125 and an example of a preferred implementation is presented and
described further
below. The regular communication mode of the communication channel 125 is one-
directional
communication from the surge protection device to a remote display. This
provides an ultimate
cyber security for the connected surge protection device. A change to a two-
directional
communication mode, when needed, is indicated using a multicolor LED 166 and
it is further
explained below. The secondary alternative transmitter 156 communicates via
the interface 104
which may utilize any currently available techniques. One preferred
implementation is to utilize
the AC power lines for a communication media channel. Implementation of
communication over
power lines are well known, described in the literature, and have been
successfully used. They do
have limitations which are recognized in the current application.
Nevertheless, for installations
with a single or a limited number of surge protection devices, the
communication over the power
lines provides a viable alternative with an intrinsic security for the
necessary status communication
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to a remote location (for example, from an electric power distribution box to
an office). Further
explanation of the communication over AC power line is beyond the scope of the
current
application. It is sufficient to acknowledge that the signaling messages are
based on a proprietary
analog implementation with the main purpose to provide an alternative secure
status
communication to a remote location. It is to be noted that the communication
over power lines is
limited to remote displays mounted on the same AC power lines.
The block diagram of a subsystem for remote display (SRD) 103 displays the
cybersecure
communication solution for a system based on the current application for
protection of electrical
and electronic infrastructure from EMP with persistent self-monitoring and
real time remote status
report. The LCM 113 and the DCC module 114, displayed in Fig. 17, form a
subsystem for remote
display (SRD) 103. A high voltage bus 123 connects the ASD subsystem 111 to
the LCM 113. A
logical level bus 124 connects the LCM 113 to the DCC module 114. A
communication output
channel 125 is a physical connection to a remote location display.
Looking to Fig. 18, a more detail block diagram of the digital communication
transceiver
153 is presented with an example of cyber secure communication to a remote
location (portal). In
this example, a possible implementation of optical communication is shown
using a multimode
fiber 160 (optical physical domain) to provide a physical layer channel to a
remote optical network
terminal (ONT) 164 of the remote display 163 from the digital communication
transceiver 153,
which includes an optical line terminal (OLT) 159. The remote optical network
terminal (ONT)
and optical line terminal (OLT) are accepted optical networks terminology. The
ONT and OLT
notation is used in this application document and in Fig. 18 refers to the
optical splitter modules
of the communication terminals, which are essential to understanding the novel
functionality of
the cybersecure optical channel communication.
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With the proliferation of edge technology devices, commonly referred to
Internet of things
(IoT) or Internet of industrial things (IoIT), the vulnerability of the IoT is
addressed and new
solutions with improved cybersecurity continue to be updated. However, it is a
continually
evolving problem. Given the utility of the devices based on this application
to protect critical
infrastructure systems, the cybersecurity of the surge protection devices
(SPD) communications is
essential. The current application provides a cybersecure solution using an
optical communication
channel from each SPD to a remote display center (portal, command and control
center, etc.). The
essence of the implemented secure channel is the utilization of coherent
optical signals with
different wavelengths to provide two separate channels in a single optical
(photonic) domain using
appropriately tuned lasers and photodetectors. This method is known as
Wavelength Division
Multiple Access (WDMA) coexistence and has many applications with different
implementations.
The WDMA is used differently in this application. Nevertheless, the
implementation of the
proposed method is compatible with commercially available network devices for
deployment of
multiple network nodes (SPDs in this case) on critical infrastructure local
area networks (LAN).
The description of the WDMA associated hardware, software, and protocols are
not in the scope
of this application. Only related aspects, specific to this application, are
described.
Referring to Fig. 18, the three submodules of the digital communication
transceiver 153
are displayed: an input/output communication module 157, an electrooptical
converter module
158, and an optical line terminal (OLT) 159. The input of the input/output
communication module
157 of the digital communication transceiver 153 is the interface 154. An
output port of the OLT
159 is the communication output channel 125, which in this example connects
directly to the
optical fiber cable 160. A communication to the remote location ONT 164 of the
remote display
163, uses an optical link with a given wavelength Xi (for example, 1310 nm),
illustrated in Fig. 18
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with a dotted line 161. The frequency of the communication is defined as to
assure real time status
report The absence of communication is an indication for a malfunction, or a
physical disconnect.
An implementation of a light source in the electrooptical converter module 158
is used to
communicate to the remote display the complete loss of input AC power using a
pulse mode optical
signal. The optical source is coupled to the optical channel 160 via OLT 159
and transmits
intermittently when the DC power is provided by the super capacitor module (DC
voltage lower
than the nominal DC voltage supply).
The regular communication on the optical channel 160 is only one-way, from the
OLT 159
of the digital communication transceiver 153, to the ONT 164 of the remote
portal 163. This the
default operational mode of "transmit only" using one-way mode of
communication to the remote
display. It is illustrated using a segment 167 of the optical channel 160 and
provides a complete
cyber-proof communication for any surge protection device using the described
one-directional
mode of communication. Each SPD has a unique identification used for network
configuration,
authentication, and during communication. Multiple identification techniques
have been
developed and are used for optical network communication and their detail
description are beyond
the scope of the current application.
The one-directional communication provides security by limiting online access
to the
connected SPDs during regular operation even when the network security is
compromised.
However, one-directional communication has obvious constrains and limitation.
Practical device
installations on any network require two-directional communication which is
the standard for
multiple reasons: configuration, time synchronization, maintenance, software
updates, and others.
This application uses a second wavelength X2 (for example, 1490 nm),
illustrated in Fig. 18 with a
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dashed line 162, to enable in a controlled manner a secure two-directional
communication on
demand, as described further.
The second wavelength X2 is not part of the network communication (which is
based on
wavelength Xi). The second wavelength )L2 is combined with XI into the optical
fiber cable 160 at
the ONT 164 and respectively separated from Xi at the OLT 159 using optical
splitters. At the
remote display location, a laser source 165 is used to generate 12 and it is
combined with Ii using
splitter 164. At the OLT 159, the X2 is separated from Xi using optical
splitter 159. The wavelength
1.2 is used to indicate to the microcontroller subsystem 152 to switch the
digital communication
transceiver 153 to two-directional communication session (full duplex
communication), as
illustrated with a segment 168 of the optical channel 160. The injection of
waveform 12 at the ONT
164 of the remote location 163 is from a source 165 that is not connected as a
communication node
on the network. A trusted user at the remote location (an operator with
security credentials) initiates
a two-way communication to one or multiple SPDs by activating the source 165.
In this regard,
the proposed security method may be viewed as an independent (separate)
authentication for the
initiation of two-directional communication. In summary, the switching to two-
directional
communication happens if, and only if, the 12 is present in the optical
channel, being transmitted
from the secured source 165, which is not connected as a node on the LAN and
is accessed only
by an authenticated operator with security credentials. Furthermore, an
optical filter 169 is a
bandpass for Xi only, preventing the possibility of injecting 12 into the ONT
164.
Looking to Fig. 19, a block diagram is presented with some additional
subcircuit details
for the analog sensors and display (ASD) subsystem 111, previously displayed
in Fig. 16. A metal
oxide varistor (MOV) 173 is use as an example of a surge protection component,
as previously
shown in Fig. 12. The MOV is presented with its thermal fuse 172, forming a
thermal MOV
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(TMOV) - a three-terminal component, connected between the AC power lines 170
and 171.
During a normal operation, the low impedance of the fuse 172 provides AC power
to analog
circuits 175 and 176 and is shunting an analog circuit 174. The analog
circuits 174, 175, and 176
form a section of analog sensor circuits 140 of the ADS subsystem 111, as
shown in Fig. 16.
Multiple sections of analog sensor circuits 140 are connected to the visual
and sound indicators of
the annunciation display module (ADM) 142 via lines 177, 178, and 179, which
form the
connecting signal bus 141 to drive visual and sound indicators of the
annunciation display module
(ADM) 142, as displayed in Fig. 16. The high voltage levels of all monitored
points are further
passed on to the high voltage bus 123.
Looking to Fig. 20, a table with the summary of all possible status conditions
and their
respective visual and sound alarm indications is presented. The Phase 1, Phase
2, and Phase 3 rows
correspond to the three LED indicators in the corners of the triangular group
of LEDs 143, shown
in Fig. 16, and associated with one of the phases of a three-phase AC power
line (Phi, Ph2, and
Ph3). The center LED in the group 143 is an LED indicating the normal status
(connected) or loss
of connection to the ground line of the AC power supply 104 and loss of ground
connection. The
AC Power and high temperature status (temperature above a preset level) is
indicated with the
LED 144 as an overall visual alarm combined with an audible alarm by a sound
source 145. During
complete loss of AC input power, the alarm visual indicator 144 and the sound
indicator 145 are
activated intermittently as shown in the columns four and five of the Table in
Fig. 20.
Many different arrangements and configurations of the system described and
depicted, as
well as components and features not shown, are possible without departing from
the scope of the
claims below. Likewise, variations in the order of the steps of the method
described, as well as
different combinations of steps, are within the scope of the present
invention. Embodiments of the
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technology have been described with the intent to be illustrative rather than
restrictive. Alternative
embodiments will become apparent to readers of this disclosure after and
because of reading it.
Alternative means of implementing the aforementioned can be completed without
departing from
the scope of the claims below. Identification of structures as being
configured to perform a
particular function in this disclosure and in the claims below is intended to
be inclusive of
structures and arrangements or designs thereof that are within the scope of
this disclosure and
readily identifiable by one of skill in the art and that can perform the
particular function in a similar
way. Certain features and sub-combinations are of utility and may be employed
without reference
to other features and sub-combinations and are contemplated within the scope
of the claims.
The subject matter of select embodiments of the invention is described with
specificity
herein to meet statutory requirements. But the description itself is not
intended to necessarily limit
the scope of claims. Rather, the claimed subject matter might be embodied in
other ways to include
different components, steps, or combinations thereof similar to the ones
described in this
document, in conjunction with other present or future technologies. Terms
should not be
interpreted as implying any particular order among or between various steps
herein disclosed
unless and except when the order of individual steps is explicitly described.
Tt is understood that while certain forms of this invention have been
illustrated and
described, it is not limited thereto except insofar as such limitations are
included in the following
claims and allowable functional equivalents thereof.
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