Study on Emergency Voltage Control for Isolated Area of Hydropower Group

After a large disturbance, a hydropower group connected to the main system through a long distance line, may split from the system and operate isolated. Based on the actual cases of MAO XIAN and JIU SHI YA hydropower groups in Sichuan province of China, the over-voltage problem in the isolated networks are presented. The feasibility of balancing the excessive charging power by generator's leading phase operation is discussed. Emergency voltage control strategy by generator excitation control is proposed. Simulation results with the actual system verify the availability of the proposed emergency control.