Analysis of the Impact of Improving the PMSG System and Battery Energy Storage on the Stability of the Power System under Grid-connected Conditions

With the growth of renewable energy power generation, there are problems of overcapacity, water, wind and solar power curtailment in some regions. Additionally, the large-scale integration of renewable energy sources has increased instability factors in the power system, necessitating a flexible control strategy to regulate the system and ensure its stability. This article first establishes a mathematical model for a dual PWM-controlled permanent magnet direct drive wind power generation system. In this model, the capacitor between the machine side and the grid side in the traditional control structure is replaced with an energy storage device to better maintain the stability of the grid-side DC voltage. Simulations are then conducted to analyze the output power characteristics of wind turbines, control the pitch angle, speed, and machine-side converter of wind turbines to achieve maximum wind energy tracking, and to analyze the operating status under different wind speeds. Secondly, the charging and discharging principle of storage batteries and their circuit models are analyzed. It is determined that during grid-connected operation, the storage battery remains in standby mode, while during islanding operation, a constant voltage charging and discharging control strategy is adopted. After establishing a simulation model for the storage battery using Simulink, load is connected to verify the charging and discharging capacity of the storage battery. Finally, a wind power generation system and a storage battery energy storage system are integrated through a PCC point into a large power grid to establish a wind-storage DC microgrid simulation model. The coordination control method during grid-connected operation is analyzed and verified, as well as the feasibility of the control strategy and the ability of energy storage devices to replace DC capacitors to maintain voltage stability.