Optimal capacitor control for unbalanced distribution systems with distributed generations

An unbalanced three-phase optimal capacitor control algorithm taking the mathematical models of Distributed Generations (DGs) into account is proposed in the paper. The formulations and solution procedures of the optimal capacitor planning and real-time capacitor control are both derived. The special topological characteristics of distribution networks are fully exploited to develop the proposed optimal capacitor control formulations. According to the characteristics of output power, DGs can be specified as constant power factor model, constant voltage model or variable reactive power model in the system analysis. Different types of DGs have different reactive power output characteristics, the mathematical formulations of different models are integrated into the proposed optimal capacitor control method. Besides, the variation of DGspsila energy sources will actually influence on the planning and operation of distribution feeders; therefore, it is also discussed in this paper. Test results show that the proposed method can integrate DGs into optimal capacitor planning and operation effectively and efficiently, and have great potential to be utilized in the future smart-grid applications.