Abstract: The reliable power supply is critical for the safe and steady operation of a power system. The reliable power support function of power supplies refers to the immediate full-load operation within its reliable capacity according to the load demand of a power system. This paper presents a calculation method of power-energy balance based on the reliable power support. The overall framework is to arrange the units on standby and in maintenance according to the power supply installation and system load demand. On this basis, the support capacity of each month (or week, or ten days) for various power sources was determined through power balance, and the annual 8760 h power-energy balance simulation was carried out. The simulation idea is to make room for wind and photovoltaic power as much as possible while meeting the minimum technical output or forced output of various power sources, so as to realize the overall power-energy balance at all time with the wind and photovoltaic power being absorbed as much as possible. This calculation method has been applied to an analysis of the Shanxi power grid with different scales of pumped storage plants, and the impact of wind power uncertainty on power-energy balance was evaluated. The results show the increase in the system’s pumped storage capacity will replace part of the thermal power capacity and increase the power for pumping, thus promoting the absorption of new energy sources. If the wind power committed too much as the power support role, in the case of wind power output is reduced by weather and other factors, the load demand could be difficult to be met even if the thermal power, hydropower and other kinds of power operate at full load, which suggests the harm to the safety and stability of power system.

Key words: power system, safe and stable operation, reliable power support, electric power-energy balance