Reactive power optimization of distribution network including photovoltaic power considering harmonic factors

Abstract

With the increasing of the penetration of distributed photovoltaic (PV) power in distribution network' the power system becomes more complex and flexible. Because of the uncertainty of photovoltaic power and the fact that photovoltaic power provides active power as well as reactive power' the traditional reactive power optimization method cannot fully meet the case of photovoltaic grid-connected system. Meanwhile' photovoltaic grid-connected system will generate harmonic pollution in distribution network' so it is necessary to control distributed photovoltaic inverters in harmony to reduce harmonics. Therefore' in this paper' considering the uncertainty of photovoltaic power, the loss of distribution network and the harmonics' the integrated reactive power optimization of photovoltaic power and capacitors is proposed, in order to guarantee the safe and economic operation of distribution network. On the basis of that the stochastic harmonic power flow was calculated and voltage total harmonic distortions (THDs) were obtained, this paper established a reactive power optimization model of distribution network including photovoltaic power considering harmonic factors. The objective function of that model is minimizing the sum of the expected values of the fundamental loss, the penalty term of fundamental bus voltages, and the penalty term of voltage THDs. Meanwhile, chance constraints were put on fundamental bus voltages and voltage THDs, which considered the uncertainty of photovoltaic power. Finally, genetic algorithm (GA) was applied. Results of IEEE-33 test system case show that the proposed reactive power optimization model can consider reducing the loss and the harmonic pollution, in order to improve the economy and security of distribution network operation.