understanding design, installation, and testing methods ... · 3/29/2017 · substation design...
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Copyright © SEL 2017
Understanding Design, Installation, and Testing
Methods That Promote Substation IED Resiliency
for High-Altitude Electromagnetic Pulse Events
Tim Minteer, Travis Mooney, Sharla Artz, and David E. Whitehead
Schweitzer Engineering Laboratories
https://selinc.com/literature/technical-papers/
i-PCGRID Workshop 2017
MYTH: “HEMP Could Cause a Protracted Nationwide Blackout”
Analyze HEMP Effects, Assess the Risk, Assist Policy Makers and Grid Operators
1 High-altitude nuclear explosion creates
gamma rays…
…which strike molecules, releasing
electrons.
…creating an EMP, which may
disrupt electronic systems.
2
4
High-Altitude Electromagnetic PulseHEMP
Earth’s magnetic field aligns
electrons…
3
Three Stages of EM Waveforms From a HEMP Event: E1, E2, E3
|E|
100 mV/m
1000 s
100 mV/m
100 V/m
100 kV/m50 kV/m
E1 + E2
E1
E2 |E3|
1 s1 ms1 ms1 ns1 ps
Time
Only E1 Waveform Has Potential to Damage Substation IEDs
EM Waveform (HEMP)Duration Similarity to
Natural Phenomena
Concern for
Substation IEDs
E1: Short-Duration Electrostatic Discharge Yes
E2: Intermediate-Duration Lightning No
E3: Long-Duration Geomagnetic Disturbance No
The Unknown Effects of RF E1 Concerned Some Policy Makers and Grid Operators
E1(t
) (k
V/m
)
0
20
30
40
50
10
0 10 20 30 40 50 60
Time (ns)
2.5 ns
rise time
23 ns
• 100 kHz – 100 MHz
AM: 535 – 1700 kHz
FM: 87.5 – 108 MHz
• Thousands of times
greater than EMC
RF immunity levels
FACT: Robust, Substation-Hardened IEDs Are HEMP Resilient in Substation Control Houses
IEEE and IEC Standards Mitigate EMC Effects
IED
IED
IED
Yard
Equip.
Yard
Equip.
H1
E1Protect cables originating
from beyond the
substation yard fence
Shielded transformers and
transient protection
attenuate > 40 dB (IEEE 1100)
H1
E1
Control houses constructed from
concrete panels with metal liners
attenuate > 20 dB
Route internal
signal wiring
along grounded
structures
Use substation-
hardened IEDs
H1
E1
Conducted
disturbance
on shields
Substation Control House
Signal wires routed in metal conduits or shielded cables grounded at
both ends and ≥ 4/0 wires with multiple ties to ground grid (IEEE 525)
Similar Mitigation Techniques of Hardened IEDs
IC
IC
ICEN, USB,
EIA-232,
4–20 mA...
PTs, CTs,
I/O
Substation engineers route signal wires along metallic
grounded framework inside the control house reducing loop area
H1
E1
Shielded, grounded
cables protect low-level
signals (IEEE 525)
Fiber-optic cables provide
IED serial communication
outside the control houseH1
E1
Substation-Hardened IED
Chassis and metal
shields attenuate
the RF E1 waveform
Ground planes
and multiple
ground points
minimize all
EMC effects
Transformers and
isolation barriers
protect integrated
circuits
MIL STD 188-125A Is Not an Appropriate Standard
Applies to Military Facilities Performing Critical Time-Urgent Missions
Use IEC Standards to Assess Substation IEDs
Power substations, power generation facilities, and electrical and electronic
equipment intended for use indoors
IEC Subcommittee 77C
High Power Transient
Phenomena of human
origin (including HEMP)
21 Publications
1996 – present
IEC Substation EMC Immunity Levels Exceed HEMP Resiliency Levels
Electrical Fast
Transient / BurstSurge
Damped
Oscillatory Wave
HEMP EMC HEMP EMCHEMP(fast)
EMC (slow)
I/O2 kV 4 kV
—
4 kV 2 kV 2.5 kV
Power (dc) 1 kV
Serial Comm 1 kV 2 kV — 2 kV 1 kV 1 kV
Evaluation of Existing Substation Designs Concluded That Substation-Hardened IEDs Are
HEMP Immune in Legacy Substations
Substation Designs That Provide Lightning Resiliency Also Provide HEMP Resiliency
Lightning EMP (50 m) RF E1 Waveform
Electric Field 100 kV/m 50 kV/m
Rise Time /
Pulse Width10 / 350 ms 2.5 / 23 ns
Energy 250 mJ 0.7 mJ
IEEE Standards Form the Basis of Legacy Substation Design Practices
IED
IED
IED
Yard
Equip.
Yard
Equip.
Cables originating beyond the substation
yard fence have always been well-
protected from severe EM effects
H1
E1
Control house material
provides 0–20 dB of
attenuation
Route internal
signal wiring
along grounded
structures
H1
E1
Substation-hardened IEDs
withstand conducted
disturbance on signal wires
Substation Control House
Signal routing in trenches within a few feet of the ground grid reduces
coupling and induced voltages
H1
E1
Mother Nature Doesn’t Read Standards –Margin Testing Ensures EMC Immunity
SEL Exceeds ESD Immunity Requirements
Air ESDContact
ESD
HEMP 8 kV —
EMC 8 kV 6 kV
SEL 15 kV 8 kV
Most Regions Will Experience Less Than E1 Max
Nuclear Environment Survivability
U.S. Army. Report AD-A278230 (1994)
50.0 kV/m
25.0 kV/m
37.5 kV/m
25.0 kV/m
12.5 kV/m
5.0 kV/m
Signal Wire Alignment, Incident Angle, Monopole Height, and Wire Length Affect Coupling
E1
H1
y
F Ground Plane
Coupled Transient Voltages From the RF E1
Waveform Are Statistically Less Than 4 kV
Pro
ba
bili
ty D
en
sity (
% / k
V)
0
20
30
40
10
0 4 8 12 16 20
IED Signal Wire Terminal
Peak Transient Voltage (kV)
Random variables
• Location under burst
• Signal wire alignment
• Monopole height
• Signal wire shielding
IEDs Have an Implied HEMP Withstand 3x Greater Than Their Rated Impulse Withstand
IED Withstand
Voltage Limit
Percentage of Installed IED Signal Wire
Terminals Exceeding Withstand Limit
23 kV (Post 2013 Withstand) 0 % (Withstand > 20 kV Maximum Peak Transient)
16 kV (Pre 2013 Withstand) 0.003 %
8 kV 1.6 %
4 kV 14.3 %
2 kV 40.6 %
Five Immunity Type Tests Demonstrate HEMP Resiliency of IEDs
Immunity Type Test
(IEC 61000-6-6)
EMC Requirement
(IEC 60255-26)
Radiated Pulse (2.5 / 25 ns) IEC 61000-4-25 Not Required
Fast Damped Oscillatory Wave IEC 61000-4-25 Not Required
Air ESD (8 kV) IEC 61000-4-2 IEC 61000-4-2
EFT/B (5 / 50 ns) IEC 61000-4-4 IEC 61000-4-4
Surge (1.2 / 50 ms) IEC 61000-4-5 IEC 61000-4-5
Third-Party Testing Confirms Substation-Hardened Relay Immunity to HEMP RF E1 Max
Third-Party Testing Confirms Relay Printed Circuit Boards Immunity to ½ HEMP RF E1 Max
• IEC 61000-6-6 provides the framework for
demonstrating HEMP resiliency of substation IEDs
• Substation-hardened IEDs are HEMP resilient in legacy
and new substations as demonstrated by
Fast Damped Oscillatory Wave testing
HEMP immunity to 50 kV/m, RF E1 pulse
HEMP survivability using air ESD margin testing at 30 kV
followed by impulse withstand testing
Conclusions
• New substation designs provide HEMP resiliency for
IEDs meeting IEC EMC and Safety requirements
• Further testing of similar substation-hardened IEDs is
not recommended
• The effects of HEMP on substation IEDs should no
longer concern policy makers, grid operators, and
others
Conclusions
