Abstract
In this paper, the effects of three typical operation modes, namely short-circuit fault, load change, and chemical energy storage on the frequency of a regional power grid after photovoltaic asynchronous interconnection were studied with different penetration ratios, taking the power grid in Northern Henan Province as the research object. It was found that with an increase in the photovoltaic penetration ratio, the maximum value of the system frequency and the fluctuation amplitude gradually increased, and the power grid system in Northern Henan became less and less stable. With an increase in the penetration ratio, the peak value of the system frequency at the corresponding node gradually increased, and the valley value gradually decreased. With an increase in load, the peak value of the frequency curve gradually increased, and the valley value gradually decreased. When photoelectricity was connected to the grid through chemical energy storage, the system stability during a short-circuit fault and load change operation was significantly improved. Compared with that before energy storage, the frequency amplitude of the system after energy storage was reduced to approximately one tenth of the original. Compared with the case before energy storage, when the load changed, the frequency amplitude of the system decreased to approximately a quarter of the original.