Research on Bi-Level Optimal Scheduling of Wind-PV-Hydro-Thermal-Storage Multi-energy Complementary Systems

The optimal regulation of multi-energy complementary systems helps to take advantages of different power sources. The growing installed capacity of wind and photovoltaic power has brought about the problems of clean energy consumption and grid peak shaving. A bi-level optimal scheduling model of wind, photovoltaic（PV）, hydropower, thermal power and energy storage is proposed to solve the problems.Firstly, considering that there are many variables and constraints involved in the optimal scheduling of multi-energy complementary, the model is processed hierarchically based on the output characteristics and complementary relationship of multiple energy sources, to reduce the complexity of model solving. Then, according to the demand of source-load coordination, clean energy consumption and power generation economy, the model is divided into the upper-level model of Wind-PV-Hydro-Storage joint optimal scheduling and the lower-level model of thermal power unit optimal scheduling. The optimization objectives of upper-level model are the minimum net load variance and the maximum clean energy generation, and the optimization objective of lower-level model is the minimum operation cost of thermal power units.The net load curve achieved by the upper-level model is used as the constraint of the lower-level model. Finally, taking the IEEE30-bus system as an example, the CPLEX solver of MATLAB platform is used to calculate three pre-defined scheduling scenarios. The results show that the anti-peak regulation of wind power and photovoltaic output will expand the peak-valley difference and variance of net load, increase the pressure of peak shavingand reserve of thermal power, and increase the power generation cost and unit loss. The participation of hydropower in multi-energy complementary systems has a significant improvement on the net load fluctuation of the power grid, which can effectively reduce the peaking pressure of the power system. Energy storage can reduce the conflict between smoothing net load fluctuation and improving clean energy generation to a certain extent. The optimal scheduling model proposed can effectively reduce the fluctuation of source and load, promote the consumption of clean energy and reduce the operation cost of the system, which contribute to the low-carbon and safe operation goals of the grid.