Low Frequency Resonance Suppression Strategy for Hydropower Photovoltaic Combined External Transmission System

Aiming at the low-frequency resonance problem existing in the hydropower photovoltaic combined external transmission system, the recovery of active power during photovoltaic entering low voltage ride through (LVRT)is analyzed, and the stages of active power recovery during LVRT are controlled theoretically. The energy generated during the LVRT of photovoltaic is also used as a disturbance quantity to cause interference to the generator, and the low-frequency resonance phenomenon caused by forced resonance is theoretically analyzed based on the single-machine infinity system. On this basis, four control strategies are proposed to suppress the low-frequency resonance phenomenon from the perspectives of disturbance source, resonance period and co-oscillation amplitude. The control strategies are verified by the hydro-power photovoltaic complementary power generation system simulation model constructed on the basis of BPA simulation platform in a China southwestern region, and the validity of the control strategies is finally verified by the example simulation.