Coordination of solar battery hybrid power plants and synchronous generators for improving black start capability

Abstract

Renewable generation utilizes inverter-based technology which is much different than the coal and nuclear synchronous machines it is replacing. The electrical network was designed around big synchronous machines providing constant dispatchable power and innate inertia to dampen frequency disturbances. The network protection system is based on high available fault current provided by the big generators. The renewable plants have a variable fuel supply, no inertia, and provide less fault current for system protection. A hybrid power plant with renewables, energy storage, and a synchronous generator can play a significant role in restoring power system operation after the occurrence of a blackout. This paper presents an improved method to utilize inverter-based resources (IBR) with existing synchronous generation to improve the black start capability while minimizing the overall system’s operation cost and providing additional ancillary grid services. A battery energy storage system is modeled with grid forming inverters to provide black start to the synchronous unit while the solar is modeled with grid following inverters. A Long-Short Term Memory (LSTM) is developed to model the auxiliary load for reducing the fuel consumption in synchronous generators and reducing the cost. Several case studies are conducted to verify the performance of the grid forming inverters with battery storage to start the largest direct online (DOL) and soft start motors. Utilizing actual synchronous generator auxiliary load data for a year, a quasi-dynamic simulation analysis is performed to determine energy storage requirements for black start. Finally, the energy benefits of the solar installation are estimated from simulating the hybrid system for 1 year. A reduced fuel burn simulation is performed by constraining the export power to the actual data and reducing synchronous generation to account for the solar generation and the reduced auxiliary load. The study finds that the IBR resources are capable of successfully black starting the synchronous generator and reducing fuel consumption and earning additional revenue from the solar plants.