Economic analysis and configuration design for the energy storage unit of photovoltaic virtual synchronous generator based on the inertia support and primary frequency control

With the increasing proportion of distributed generation (DG) in electrical power systems (EPSs), the lack of grid inertia and damping has posed great challenges to the stability and operation of EPSs. To address these problems, the concept of a virtual synchronous generator (VSG) has been proposed. As the physical basis of virtual inertia, the energy storage unit directly affects the performance and operating cost of the VSG. In this paper, the energy change of the energy storage unit during the frequency control process is calculated. Based on this calculation, the charge and discharge behavior of the energy storage unit can be inferred according to the VSG parameters and the frequency deviation data. Then, combined with the improved battery cycle life model, the operating cost of the energy storage unit when the VSG participates in frequency control can be obtained. Based on the data provided by the British electricity system operator (ESO), a case is studied, and the effects of the control parameters and battery rated capacity on the operating cost is analyzed. The analysis results can provide an economic reference for the parameter selection and energy storage unit capacity configuration of the VSG. Moreover, the simulation results validate the accuracy and efficiency of the proposed method.