Research on Water Hammer Effect and Cooperative Frequency Regulation Technology of PV-HBESS Compensated Hydroturbine

The water hammer effect in a hydroturbine and improper setting of the PID parameters of a governor can cause a hydropower unit to provide negative damping to the corresponding hydro power generation system, affecting its frequency. Therefore, a collaborative control method using photovoltaic (PV) and hybrid battery energy storage system (HBESS) is proposed to compensate the water hammer effect. First, models for hydropower, PV, and HBESS are established. Second, a coordinated control strategy for HBESS and the PV system is presented, where the PV system employs a variable load reduction frequency regulation strategy based on power output and frequency deviation changes. The HBESS follows the state of charge, frequency change rate, and frequency deviation changes, with the supercapacitors utilizing virtual inertia control and lead-carbon batteries employing droop control to rapidly respond to the water hammer effect. Last, a control strategy based on model predictive control (MPC) optimized with a whale optimization algorithm (WOA) is proposed to manage the hydropower unit parameters and the coordinated hybrid battery energy storage system to mitigate the water hammer effect. The MPC-WOA can rapidly identify the optimal PID parameters for the hydropower unit. The proposed strategy effectively suppresses fluctuations in turbine mechanical power and system frequency. Real-time simulation on the RTLAB platform validates that the proposed control method improves system frequency adjustment time by 45.40% compared to systems without compensation and reduces power feedback fluctuations by 87.22%, significantly enhancing frequency stability against the water hammer effect.