220kV Substation Capacity Demands Assessment Method Considering Irradiance of Regional Power Grid

The problem of insufficient capacity of the main transformer has always been the key factor restricting the security operation of the power grid. The continuous increase in the penetration of distributed photovoltaics puts forward new requirements for renewable energy access and power load down-grid ability of the power system. The irradiance factor of the power grid and the development of renewable energy are considered. The capacity deficits of the 220kV substation based on the guideline capacity-load ratio are calculated by analyzing the regional distributed photovoltaic output simultaneity rate at noon and the installed situation of distributed photovoltaic. Then, the load rate of the main transformer N-1 failure of the heavyduty 220kV substation is analyzed. The additional 220kV transformer capacity is calculated when the transferred load of the lower power grid is considered and the renewable energy source is not adopted. Finally, the evaluation index of 220kV substation capacity demand of the regional power grid is proposed, which is used to evaluate the relationship between the shortage of substation capacity of each heavy-duty substation and the overall 220kV substation capacity shortage in the region. The effectiveness and adaptability of the proposed method are verified by an actual power grid.