Frequency control strategy for parallel operated battery systems based on droop characteristics by applying H∞ control theory

Stand alone ac power supply system like that is designed for isolated islands is subjected to large frequency and voltage fluctuations caused by power deviation of wind turbine generator and load demand. An autonomous decentralized frequency control system of parallel operated decentralized generators based on droop characteristic is presented in this paper. The conventional droop control methods proposed in past researches exhibit slow and oscillating dynamic responses. Moreover, the conventional droop control is affected by measurement noise when the fast controllability of the system is emphasized. This paper proposes the improved droop control system for load sharing of multi operated decentralized generators by applying H_∞ control theory, improving transient response of droop control and robustness against measurement noise and parameter variations. Simulation results validate the effectiveness of the proposed control system.