Impacts Of Grid-connected Photovoltaic Generation On Distribution System

With the development of photovoltaic (PV) generation and grid-connected PV(GPV), more and more PV systems are incorporated into distribution system (DS),which leads to various impacts on DS.Firstly, impacts caused by GPV on DS voltage are analyzed in mechanism. Thetime-sequential probabilistic model of output power of GPV is built by thesimulation method of sequential Monte Carlo (MC). Three-phase probabilistic loadflow at1-hour time step in DS with GPVs is calculated in order to analyze impactstriggered by GPVs with different capacities, sites, power factors, forms andrelativities of weather on DS voltage. Then three-phase probabilistic load flow at5-minutes time step is analyzed to research the function of GPV with stored energyin leveling the fluctuation of DS voltage. Besides, impacts of GPV on DS voltageregulation are analyzed. Different approaches for resolving problems of DS voltageare concluded.Next, based on the analysis of fault characteristics of GPV when faults occur inDS, the paper analyzes impacts of GPV on DS various protections and relatedprotective devices. Different protection schemes presented for DS with GPV aresummarized. Pilot protection with added currents and the protection method basedon the current information of the whole DS are proposed.Thirdly, impacts on power quality of DS due to harmonic component and DCcomponent of GPV are analyzed. Impacts caused by GPV on DS dispatchingautomation, reliability and planning and design are summed up and some problemsin solving these impacts are discussed.Finally, some evaluation indexes are given from power quality, network loss,reliability and security of DS in order to assess the degree of impacts of GPV onDS.