Frequency control of energy storage system based on hierarchical cluster structure

Deviation of power frequency can greatly impact power system reliability, power quality and economic efficiency. This paper proposes the frequency control of energy storage system based on hierarchical cluster structure. A central agent named by power management system (PMS) contracts with utility for providing the frequency regulation. The agent also manages the whole cluster structure and balances the energy of each storage device. Several local sub-agents named by the energy storage system controllers (ESSC) intermediate between the power management system and the subordinate energy storage devices. The sub-agents perform the frequency response control by P-f droop, and set the power reference to the each energy storage device. Through the demonstration test, response time and ramp rate of the proposed structure and algorithms are calculated and performance of this system is confirmed.