Essential Reliability Services From

PV Plants

Mahesh Morjaria, Ph. D.VP, P V Systems

Enabling a world poweredby reliable, affordable

solar electricity.

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California ISO

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California ISO

,--~NREL llt-!!!!~ NATIONAL RENEWABLE ENERGY LABOl'1ATOl'1Y

' ' First Solar®

Can variable energy resources provide essential reliability services

to reliably operate the grid?

• NERC identified three essential reliability services to reliably

integrate higher levels of renewable resources 1. Frequency Control

2. Voltage Control

3. Ramping capability or Flexible Capacity

• Test results demonstrated utility-scale PV plant has the capability

to provide these essential reliability services

• Advancement in smart controls technology allows these plants to

provide services similar to conventional resources

• VERs (Variable Energy Resources) with the right operating

characteristics are necessary to decarbonize the grid

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PV Plant Schematic

POWER GRID SUBSTATION

DC

• • •

Sunlight to DC Power DC Power to AC Power AC Power to Grid

SWITCHGEAR

AC

SOLAR ARRAYS COMBINER BOX

DC

POWER CONVERSION STATION

69 to 765kV (AC)

Typical DC Voltage 1kV or Typical AC Collection Voltage 1.5kV 34.5kV

(Alternatives 4.16kV to 27.6kV)

Typical DC Voltage 1kV or 1.5kV Typical AC Collection Voltage 34.5kV (Alternatives 4.16kV to 27.6kV)

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Sunlight to DC Power DC Power to AC Power AC Power to Grid

POWER GRID SUBSTATION

DC

• • •

SWITCHGEAR

AC

SOLAR ARRAYS COMBINER BOX

DC

POWER CONVERSION STATION

69 to 765kV (AC)

• Checks grid’s actual conditions and required set points

• Sends individual instructions to each inverter based on location, losses, and performance

• Controls quality of power coming out of the PV plant CCU{Q)~edl-Uroxop losed-loop crc{Q)nfr{Q)U~ ontrols ataJt t 100 100 mmmu~erc{Q)nd/~i illiseconds!

Operator Enters Set Points

Plant SCADA system

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Grid Parameters

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Plant Control System Enables Grid Friendly Features

Patent No. 8,774,974. Real-time photovoltaic power plant control system

Available MW

30MW Headroom Commanded MW

Minimum Allowed MW

MORNING Available MW Min allowed MW Commanded MW Measured MW

230

220

210

200

190

180

170 0 200 400 600 800 1000 1200 1400

RELATIVE TIME (sec)

Measured MW

POW

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W)

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Measured MW

POW

ER (M

W)

Avaliable MW Min Allowed MW Commanded MW Measured (MW) 285

280

275 30MW Headroom Available MW 270

Commanded MW 265

260

255

250

245 Minimum Allowed MW 240

0 200 400 600 800 1000 1200 1400 RELATIVE TIME (sec)

MIDDAY

AGC Participation Tests – 300 MW Utility-Scale PV Plant

• 30MW headroom • 4-sec AGC signal provided to

Plant Controller • Tests were conducted for

— Sunrise — Middle of the day — Sunset

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PV Plants Outperform Conventional Resources in Frequency Regulation

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Hydro Combined Cycle

Limited EnergyStorage

Gas Turbine

0%

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20%

30%

40%

50%

60%

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80%

90%

100%

Blue bars taken from the ISO’s informational submittal to FERC on the performance of resources providing regulation services between January 1, 2015 and March 31, 2016

Solar PV (Middle ofthe Day)

Solar PV (Sunset)

Solar PV (Sunrise

Regulation accuracy by PV Plant is about 24-30% points better than fast gas turbines

40%

63%

87-93%

40%

California ISO

http://www.caiso.com/Documents/TestsShowRenewablePlantsCanBalanceLow-CarbonGrid.pdf

Utility-scale PV solar is a flexible resource that can enhance grid reliability

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USING RENEWABLES TO OPERATE A LOW-CARBON GRID:

Demonstration of Advanced Reliability Services from a Utility-Scale Solar Pl/ Plant

California ISO

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Dispatchable PV Plant • Solar can provide NERC-identified essential services to reliably

integrate higher levels of renewable resources, including:— Frequency Control— Voltage Control— Ramping capability or flexible capacity

• Automated Generation Control (AGC) regulation accuracy of 24-30 %points better than fast gas turbines

• Reduces need for services from conventional generation— Goes beyond simple PV energy value— Enables additional solar— Reduces need for expensive storage

http://www.caiso.com/Documents/TestsShowRenewablePlantsCanBalanceLow-CarbonGrid.pdf

CCA!SO: AISO: “66GGrkdl rid Ffriencdliy riendly UlUtmtty-SteiSlie tility-Scale PIPV V PPi©1nt§ lants a©1re re Essential for Large-Scale PV Integration”

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PV Plants with Grid Services Can Address Some of Hawaii Grid Challenges

• Traditional Generating resources arebeing displaced, along with theancillary services provided by theseresources

• Dispatchable generating resourcesare increasingly being taken offline toaccommodate production from bothgrid‐scale renewable energy resourcesand DER.

• As the grid becomes more dynamic,the need for resources that canregulate grid frequency and providefast frequency response is increasing

Source: “Modernizing Hawai‘i’s Grid For Our Customers”, June 2017 Draft Report

Discussion Points

• Use PV plants More Flexibly … both as energy source/reliability services …”low hanging fruit”

• Some level of curtailment may be more economical for system flexibility …add storage later when it becomes economical

• Reliability services from PV plant does not impact O&M cost unlike conventional plant

• Use DER inverters for voltage support (volt-var; volt-watt functions)

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