EPIC 2019: Dominion Energy’s Usage of RTDS HIL Technology to Strengthen Their Grid

EPIC 2019 Dominion Energy’s Usage of RTDS HIL Technology to Strengthen Their Grid Joseph Petti 10/28/2019

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November 1, 2019

Grid Transformation • New technologies have disrupted the grid • Distributed Generation • FACTS Devices

• Dominion must create new solutions to maintain reliability • Solutions must be tested thoroughly prior to field installation • RTDS Hardware in the Loop testing 2

November 1, 2019

Real Time Digital Simulator • Real time simulation is too demanding for a regular PC • IBM multicore processors

• Analog and digital inputs/outputs • +/- 10V • +5 to +24V

• Connects to Doble amplifier to create secondary values of current and voltage 3

November 1, 2019

Hardware-in-the-Loop

Doble Amplifier

Relay Outputs

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November 1, 2019

Commercial Relay Customizable Logic

Dominion Test Cases • DG Transfer Trip • •

Power Line Carrier communication is common in the Dominion system but is not as reliable as it once was Back up settings allow DG to stay online during communication outages

• Bidirectional Power Flow • • •

System was built for a radial grid DG installation leads to bidirectional power flow Feeder protection needs to be modified for present and future system usage

• Series Compensated Lines • • •

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Increase real power transfer capability Improve stability Transmission protection schemes are impedance based

November 1, 2019

Local Protection for DG Sites • Incorporate various elements into the existing recloser at the PCC • Voltage, frequency, phase, rate of change of frequency

• Recloser constantly checks for communication signal

• When none is detected the back up protection is active for 4 minutes • Allows time for communication to be reestablished

• 4 minute limit has potential to be extended if pilot performs well

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November 1, 2019

Test Bench Setup 34.5 KV / 13.8 KV 230 KV /34.5 KV

F3

PCC CT

R Utility Source

F1 S

PT

DER1 5 MW

Relay

F2 Load 1

DER2 5 MW

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November 1, 2019

Results • Various scenarios and simulations were executed: • • •

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Various operating conditions - Heavy/light local load & with/without DER2 Faults at various locations - 3 phase/single phase (High Z/Low Z) 58 total test cases

Operating Condition

Number of Test Cases

Successful Test Cases

With DER2

17

16

Without DER2

31

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November 1, 2019

PG Fault on Adjacent Circuit 34.5 KV / 13.8 KV

PCC

230 KV /34.5 KV

CT

R Utility Source

S

PT

DER1 5 MW

Relay

F2 Load 1

DER2 5 MW

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November 1, 2019

PG Fault on Adjacent Circuit

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November 1, 2019

Island with 10% Excess Load 34.5 KV / 13.8 KV

PCC

230 KV /34.5 KV

CT

R Utility Source

S

PT

DER1 5 MW

Relay

Load 1

DER2 5 MW

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November 1, 2019

Island with 10% Excess Load

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November 1, 2019

Findings • Voltage, current, frequency, phase, and rate of change of frequency are excellent indicators of a grid event • No one element can detect all disturbances

• A perfect island will not cause the algorithm to trip the site offline • No active sites with spinning generation and inverter based generation for now

• Pilot installation occurred early October 2019

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November 1, 2019

Bidirectional Power Flow • Directional Overcurrent •

The DOC element, 67, combines directionality with the standard overcurrent element

•

The directional element uses phase angle displacement between the current phasor of a particular phase and the reference variable to determine the directionality (forward or reverse)

•

Usually single phase elements

• Reverse Power

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•

The RP element, 32R, is also a directional protection element that relies upon both voltage and current values to determine reverse power

•

Measures 3 phase active or reactive power to detect reversal

•

Normally, not used for single phases for fault detection due to availability of OC elements

•

Detects reversal of power for a non-exporting DER at the PCC during sudden loss of generation at the utility side or Loss of Mains (LOM) situation November 1, 2019

Test Bench Setup Feeder1

230 KV /34.5 KV

F3

F2

PCC

34.5 KV / 13.8 KV CT

R

Utility Source

F1

S

S Relay

Load 3

Feeder2

Load 2

DER2 5 MW

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November 1, 2019

Load 1

DER1 5 MW

PT Local Load

Results • Various scenarios and simulations were executed: • • •

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Various operating conditions - Heavy/light local load & with/without DER2 Faults at various locations - 3 phase/single phase (High Z/Low Z) 12 scenarios in total in each case(with and without DER2)

Operating Condition

Successful indication by DOC

Successful indication by RP

Without DER2

12

3

With DER2

12

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November 1, 2019

Scenario 1: High Z Three phase fault at F1

PCC

Feeder1

34.5 KV / 13.8 KV CT

F1

R

S

Utility 230 KV /34.5 KV Source

S Relay

Load 3

Feeder2

Load 2

DER2 5 MW

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November 1, 2019

Load 1

DER1 5 MW

PT

Local Load

Scenario 1

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November 1, 2019

Scenario 2: Bolted 3 phase fault at F1

PCC

Feeder1

34.5 KV / 13.8 KV CT

F1

R

S

Utility 230 KV /34.5 KV Source

S Relay

Load 3

Feeder2

Load 2

DER2 5 MW

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November 1, 2019

Load 1

DER1 5 MW

PT Local Load

Scenario 2

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November 1, 2019

Scenario 3: High Z single phase to Ground fault at F2

Feeder1 230 KV /34.5 KV

PCC

F2

34.5 KV / 13.8 KV CT

R

S

Utility Source

S Relay

Load 3

Feeder2

Load 2

DER2 5 MW

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November 1, 2019

Load 1

DER1 5 MW

PT

Local Load

Scenario 3

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November 1, 2019

Findings • Low fault impedance causes the voltage to collapse, which leads to a negligible power magnitude • During phase to ground faults power in one phase might reverse direction, however the three phase power is not considered in the reverse direction as the other two phases increase power to compensate

• Reverse power is not a reliable indicator of fault identification, and the DOC element should be considered instead for feeder protection

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November 1, 2019

Series Compensated Lines • Provide numerous benefits •

Increase real power transfer capability

•

Improve stability

• Create several line protection challenges •

Schemes are typically impedance based

•

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Directionality issues

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đ?‘‰1 đ?‘‰2 đ?‘ƒ= sin đ?›ż đ?‘‹đ??ż Power Transfer Equation

đ?‘‰1 đ?‘‰2 đ?‘ƒ= sin đ?›ż đ?‘‹đ??ż − đ?‘‹đ??ś Power Transfer Equation with Series Compensation

Transmission Line Protection • Directional comparison blocking (DCB) •

Zone 1 covers 80% of line with no delay

•

Zone 2 covers 150% with delay

•

Zone 3 senses reverse fault and blocks

Zone 1

Fault on Line

B Steady State

Zone 3 A

A

B Zone 1 Zone 2 R-X Plane for DCB

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1 November 2019

Project Basis • Two series capacitors on Dominion Energy system • The lines are critical for system stability

Bath County Pumped Storage Facility 26

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Series Capacitors in ASPEN OneLiner Software

Test Cases • Five single line to ground (SLG) fault cases • Cases 1-4 assume 0 fault impedance • Case 5 assumes 20 Ohm fault impedance

Test Cases for Hardware-In-The-Loop Simulation

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Case 1&2: Bath County Terminal • Expected zone 2 to assert • 10.417 ms delay

Blocking Bit Zone 2 Blocked

Bits in Relay

MOV Bypass

Zone 2 Asserts

Steady State

Fault

Zone 2 Fault Case 28

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R-X Plane Seen by Bath County Relay

Case 1&2: Lexington Terminal • Expected zone 3 to assert • Blocking signal sent Bits in Relay

Reverse Element Asserts

Zone 3 and Blocking Signal Asserts

Zone 3 Fault Case 29

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R-X Plane Seen by Lexington Relay

Findings • All faults within zone of protection detected • All outside zone faults blocked as intended

• Zone 1 operation on compensated lines requires further analysis

Summary of Simulation Results

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Conclusion • RTDS allows Dominion to study new technology and ideas to strengthen the grid • Various generation, impedance, and communication strategies can be explored

• Allows us to discover weaknesses in the scheme and engineer a better solution • Fun fact: Part of my Master’s Thesis is a RTDS project I completed at Dominion

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1 November 2019