The accurate calculation of total supply capability(TSC)can effectively guide the planning and operation of the power network. An alternating iteration method between the complete power network model and 220 kV area power grid model is presented to calculate the TSC of 220 kV area power grid based on the non-linear mathematical model with AC power flow and N-1 static security constraint. The proposed method is able to decrease the scale of calculation

accelerate the calculation speed

and effectively improve the accuracy of the TSC. There are some requirements for the load distribution balance in actual power network. Therefore

TSC model is proposed considering load equilibrium. Finally

TSC of the models with and without considering load equilibrium is calculated at a 220 kV area power grid in Guangzhou. The results are compared and analyzed to verify the feasibility and effectiveness of the proposed method and the model. This work is supported by National Natural Science Foundation of China(No. 51377058).