Essential Reliability Services From PV Plants

Transcription

1 Essential Reliability Services From PV Plants Mahesh Morjaria, Ph. D. VP, PV Systems Enabling a world powered by reliable, affordable solar electricity.

2 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 Page 2

3 PV Plant Schematic Sunlight to DC Power DC Power to AC Power AC Power to Grid DC AC SOLAR ARRAYS COMBINER BOX POWER CONVERSION STATION SWITCHGEAR SUBSTATION POWER GRID 69 to 765kV (AC) DC Typical DC Voltage 1kV or 1.5kV Typical AC Collection Voltage 34.5kV (Alternatives 4.16kV to 27.6kV) 3

4 Plant Control System Enables Grid Friendly Features Sunlight to DC Power DC Power to AC Power AC Power to Grid DC AC 69 to 765kV (AC) SOLAR ARRAYS Patent No. 8,774,974. Real-time photovoltaic power plant control system COMBINER BOX DC Typical DC Voltage 1kV or 1.5kV POWER CONVERSION STATION SWITCHGEAR Typical AC Collection Voltage 34.5kV (Alternatives 4.16kV to 27.6kV) SUBSTATION POWER GRID 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 Closed-loop controls at 100 milliseconds! 4

5 POWER (MW) POWER (MW) AGC Participation Tests 300 MW Utility-Scale PV Plant MORNING 230 Available MW Min allowed MW Commanded MW Measured MW MW Headroom Commanded MW Available MW Measured MW Minimum Allowed MW RELATIVE TIME (sec) MIDDAY Avaliable MW Min Allowed MW Commanded MW Measured (MW) 30MW Headroom Commanded MW Available MW Measured MW Minimum Allowed MW RELATIVE TIME (sec) 30MW headroom 4-sec AGC signal provided to Plant Controller Tests were conducted for Sunrise Middle of the day Sunset 5

6 PV Plants Outperform Conventional Resources in Frequency Regulation 100% 90% 80% 70% 60% Regulation accuracy by PV Plant is about 24-30% points better than fast gas turbines 63% 87-93% 50% 40% 40% 30% 20% 10% 0% Steam Turbine Pump Turbine Hydro Combined Cycle Limited Energy Storage Gas Turbine Solar PV (Middle of the Day) Solar PV (Sunset) Solar PV (Sunrise 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,

7 Utility-scale PV solar is a flexible resource that can enhance grid reliability 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 %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 CAISO: Grid Friendly Utility-Scale PV Plants are Essential for Large-Scale PV Integration 7

8 PV Plants with Grid Services Can Address Some of Hawaii Grid Challenges Traditional Generating resources are being displaced, along with the ancillary services provided by these resources Dispatchable generating resources are increasingly being taken offline to accommodate production from both grid scale renewable energy resources and DER. As the grid becomes more dynamic, the need for resources that can regulate grid frequency and provide fast frequency response is increasing Source: Modernizing Hawai i s Grid For Our Customers, June 2017 Draft Report 8

9 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) 9