Abstract: With the large-scale integration of wind and photovoltaic power into power system, it is necessary to perform power balance analysis with annual scale and hourly granularity for taking into account their uncertainty. A new power balance analysis method is proposed in terms of a provincial power system containing a complex power source structure, internal section limitation, and external AC/DC tie lines. The method is based on a rolling balance analysis with a daily cycle. For a specific day, the problem is simplified and the solution scale is reduced by dynamically aggregating similar power sources in each partition. By constructing a thermal power start-up optimization model, the thermal power start-up capacity of each partition is determined based on the principle of balanced start-up under the consideration of section constraints. By reasonably designing an optimal scheduling model, power balance calculation is achieved while meeting the principles of balanced scheduling of similar power sources in different zones and sequential calling of different types of power sources in the same zone. The example is based on actual provincial power system data and verifies the effectiveness, rationality and rapidity of the method.