Joseph Petti, Kevin Phelps, Chris Mertz, and Kyle Thomas

Dominion Energy®

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Microgrid Islanding via GOOSE Messaging

Microgrid Introduction

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A microgrid is a group of interconnected loads and distributedenergy resources within clearly defined electrical boundariesthat acts as a single controllable entity with respect to thegrid. A microgrid can connect and disconnect from the grid toenable it to operate in grid‐connected or island mode.‐ Department of Energy

Potential benefits include….. Enhanced local reliability Reduced emissions Improved system resiliency Lowered energy cost

• Microgrid market is growing• Estimated revenues of $20 Billion in 2020

• Many predict utilities are destined to play a role• ComEd – “Community of the Future” – Chicago, IL• Duke Energy – “Microgrid Training Center” – Mount Holly, NC• National Grid – “Clarkson U. Microgrid” – St. Lawrence County, NY• S&C Electric – “Santa Rita Jail Microgrid” – Alameda County

• Develop Dominion Energy owned microgrid• Validate innovative solutions in physical setting

Project Value

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Clarkson University Microgrid

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Santa Rita Jail Microgrid

• Incorporate a microgrid into Dominion Energy’s grid safely• Tasks

• Develop an islanding scheme• Alter existing DG trip scheme

• Create and simulate model to validate microgrid functionality• RSCAD• SEL relays• RTDS

Project Summary

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Dominion Energy’s Scheme for Tripping DG Offline

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Proposed Scheme for Microgrid Islanding

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RTDS Hardware-in-the-Loop Simulation

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Simulation Goals

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• Stabilize MG after transition from grid connected to islanded mode• Need to ensure voltage, frequency, and power quality are established

extremely quickly (ideally < 1 second)• Observable events

• Relay actions• Fault recognition• Islanding • MG generation start up

• Voltage Stability• Return to 1 p.u.

• Frequency Stability• Return to 60 Hz

Communication Protocol: GOOSE Messaging

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• SEL relays communicate GOOSE messages• Generic Object Oriented Substation Events (GOOSE)

• Defined by IEC 61850• Allows multiple devices to simultaneously receive same message• Brand Independent

• Promotion of high inter‐operability between systems from different vendors• Ethernet• VLAN

• Priority Levels – allow separate networks within a physical network

Testing Procedure Continued

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0

0.2

0.4

0.6

0.8

1

1.2

0.197 0.207 0.217 0.227 0.237 0.247

Volta

ge (p

.u.)

Time(s)

MG Load Voltage Vs. Time

MG Load Voltage

Results – Relay Actions

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T1 T2 T3

• T1: Fault occurs: 0.2s

• T2: MG islands: 0.226s

• T3: MG generation comes online: 0.237s

• 37 ms from fault to MG control process completion

Results – Voltage Stabilization

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0

0.2

0.4

0.6

0.8

1

1.2

0.197 0.207 0.217 0.227 0.237 0.247 0.257

Volta

ge (p

.u.)

Time(s)

MG Load Voltage Vs. Time

MG Load Voltage

T1 T2

• T1: Fault occurs: 0.2s

• T2: Voltage stabilizes: 0.262s

• 62 ms from fault to MG load voltage stabilization

Results – Frequency Stabilization

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T1 T2

• T1: Fault occurs: 0.2s

• T2: Frequency stabilizes: 0.274s

• 74 ms from fault to MG frequency stabilization

0

20

40

60

80

100

120

0.195 0.215 0.235 0.255 0.275

Freq

uenc

y (H

z)

Time(s)

MG Frequency Vs. Time

MG Frequency

• SEL relay communication via GOOSE messaging is suitable for microgrid islanding

• Relay to relay via GOOSE: 6 ms• Voltage stabilization: ~4 cycles• Frequency stabilization: ~4 cycles

• SEL relays and microgrid controls can be combined for islanding scheme

Conclusions

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• Further utilize SEL‐3530 for more advanced schemes• Load Shedding within microgrid

• Incorporate more distribution system detail into RSCAD model• Include additional forms of energy generation

• Storage ‐ Batteries• Wind

• Implement microgrid in Dominion Energy territory

Future Work

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Questions?

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