Studies have been done to power active and reactive balance through calcultion,solutions are presented in regarding to the power restricting and the supply necessary reference to the program development of yuncheng power Network.

To find an appropriate control strategy by which the unbalanced power can be influenced and the superfluous energy can be exhausted, the motion equation of generator rotor is observed in the viewpoint of Newton’s second law of motion and it can be known that the basic reason causing system unstability is the superfluous energy cumula.

In order to improve the control strategy of APF(Active Power Filter),the active power balance among voltage-source APF,source and nonlinear load is analyzed in this paper,based on the analysis a direct source current control strategy of shunt APF found on active disturbance rejection controller(ADRC) is presented.

By introducing the concept of node imbalance power,the problem of maximum transmission capacity of power network is described as an optimal power flow model,which changes the common practice of setting the direction of load increase,and makes the result more practical.