Operational characteristics and optimization of Hydro-PV power hybrid electricity system

Abstract

Hydropower is the largest capacity and most realistic way to regulate photovoltaic (PV) power fluctuation at present. However, the stability issue of hydropower unit caused by the volatility of PV power comes to be concerned. A novel model of hydro-PV power hybrid system considering the high-order nonlinear coupling relationship of hydraulic, mechanical, electrical factors of hydropower unit, is proposed in this paper, which contains two multi-objective functions, two capacity indexes, two control strategies, and two computational models. The control strategies with power complementary control (PCC) and primary frequency control (PFC) promote hydropower smoothes the fluctuation of PV power, but the volatility of PV power increases the risk of instability of hydropower units. Furthermore, under the premise that hydropower undertakes dual tasks: regulating load demand and compensating PV power, the stability and power quality of the hybrid system are guaranteed when β is within 60%. If hydropower unit is only responsible for compensating PV power, β will increase slightly. Once PV power exceeds the regulation capacity of hydropower, it will lead to the oscillation of hydro-PV power hybrid electricity system (HPP-HES), threatening the safety of HPP-HES and power grid.