Application of power circle to reactive power optimization

Reactive power optimization has been a hard problem for years. However, the existed optimization algorithms are usually complex in calculation and not obvious in physical meaning. To study a simple and effective method for reactive power optimization, this paper puts forward a concept of optimal reactive load, and proposes a method called power circle method. With power circles, this paper presents a geometric explanation of minimization of active power loss and obtains the analytic expression of the optimal reactive load. And a simulation is carried out to verify the effectiveness of power circle method on reactive power optimization. The results show that power circle method has a good effect on loss reduction. Those conclusions provide theoretical basis for reactive power optimization of transmission line.