Category: Grid Modernization
Our Engineering team has been working to better understand advanced SCADA control options for Utility scale distributed solar photovoltaics (PV) and battery energy storage systems (BESS). This presentation will demonstrate how their impacts on electric grid system operation can be beneficial rather than problematic. Properly implemented, integrated control of advanced PV Systems and BESS technologies improves grid management. It does this by reducing the number of equipment operations to save equipment wear and tear; by improving customer power quality by reducing voltage excursions; and reducing system energy demand through Voltage regulation.
Though traditional synchronous generators are capable of injecting reactive power into the system or absorbing excess reactive power—and can do so quickly—the operating and opportunity costs associated with this method of voltage control are relatively high. PV and BESS inverters are designed to be capable of absorbing reactive power to counteract voltage rise at the point of connection and they are capable of injecting reactive power to support voltage droop. Moreover, if inverters are required or allowed to participate in voltage control and reactive power management, the utilities can accommodate higher PV penetration levels.
The list of utilities with reactive power requirements that Trimark has worked with includes Los Angeles Department of Water & Power, National Grid, Pacific Gas and Electric Company, San Diego Gas & Electric Company and Southern California Edison. Most of our experience is on the distribution network, and utilities typically require reactive capabilities of 0.95 or 0.90 lag-to-lead power factor at the point of interconnection.
At the plant level, an integrated SCADA controller controls the reactive power magnitude, power factor or voltage at the point of interconnection. With a plant-level controller, system designers also have the option of using other equipment, such as switched capacitor banks, for reactive power control. At the inverter level, plant operators can set internal parameters in the inverter software to allow the inverter to operate at a fixed power factor or to vary reactive power depending upon the generation level or the voltage at the inverter terminals.
Utility-scale PV power plants invariably comprise multiple inverters, often measured in the tens or even hundreds. BES systems add even more. Plant-level controllers allow operators to coordinate these individual inverters and operate them in aggregate as a single large generator. This capability is key to integrating variable energy resources into the grid.
Dean Schoeder– Chief Marketing Officer, BSEE, EIT, Trimark Associates