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Distributed Energy Resources Modeling

NERC LMTF Aug 8

Jameson Thornton, Transmission Planning

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NERC LMTF Aug 8-9

PG&E System

70,000 Square Miles18,600 miles transmission~5 million customers• 15 million people

Peak load ~20,000 MW

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NERC LMTF Aug 8-9

Distribution SystemSubstation

230 kV

M

35MW

15MW

12MW2MW

14MW

14MW3MW

Distribution Models

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NERC LMTF Aug 8-9

Substation

230 kV

Distribution System

Transmission Model

15MW

Substation

230 kV

M

35MW

15MW

12MW2MW

14MW

14MW3MW

5MW

40MW

-2MW

Native Load

Energy Efficiency (projected)

Down Stream DG (includes behind the meter)

Upstream DG (not included in the recorded load)

Dist. Vs. Transmission Models

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NERC LMTF Aug 8-9

DG PV Stats

• DG Penetration is over 15% of PG&E System Peak (~3,000 MW)

• Total DG has increased about 45-55 MW/montho 76 MW in Dec 2015,

largest single month increase

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NERC LMTF Aug 8-9

CEC Lowered 2026 Demand Forecast by 3,770 MW

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NERC LMTF Aug 8-9

0

500

1,000

1,500

2,000

2,500

10,000

12,000

14,000

16,000

18,000

20,000

22,000

0:00 2:00 3:59 5:59 7:59 9:59 11:59 13:59 15:59 17:59 19:59 21:59 23:59

PV o

utpu

t (M

W)

PG&

E Sy

stem

Loa

d (M

W)

Time

System Load Vs. PV Output

Net Load

Gross Load

Future Load?

Solar Output

DG impact on demand

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NERC LMTF Aug 8-9

Load with AAEE and DG

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NERC LMTF Aug 8-9

High Voltage Concerns

Surge Impedance Loading (SIL)

• See diagram to left

Ferranti Effect• An increase in voltage at the

end of a long, lightly load transmission line.

Higher voltages may need additional mitigation

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NERC LMTF Aug 8-9

Voltage Rise with Light loads

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NERC LMTF Aug 8-9

Dynamic Load Model CMPLDWG

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NERC LMTF Aug 8-9

CMPLDWG – DG Component

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NERC LMTF Aug 8-9

Frequency Response with Increased Renewables, Modeling Assumptions

DG starts to trip

all DG trips

DG starts to trip

all DG trips

Voltage 0.95 0.9 0.7 0.5Frequency 59.6 59 59 58

"Adjusted" "Normal"

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NERC LMTF Aug 8-9

Rule 21 reference

DG starts to trip all DG trips

Voltage 0.88 0.88Frequency <30kW 59.3Frequency >30kW 59.8 57

Rule 21

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NERC LMTF Aug 8-9

Future Work

Need to study more scenarios, higher amounts of DG, combinations of high/low load with high/low output of solar DG

Further evaluate dynamic parameters, run further stress tests, collaborate with vendors of software for deeper understanding of models

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NERC LMTF Aug 8-9