Limit Capacity Evaluation Of Photovoltaic Generations And Research On Extended Reactive Power Optimization In Distribution Networks

For half a century,countries around world have set up efforts to exploit fossil fuels for the economic development.However,under the challenge of resource,environment constraint and climatic variation,countries all take measures to improve the structure of energy and look for alternative renewable energy.Distributed generation(DG)will become the main form of clean energy utilization and the important development direction of smart power grid.DGs represented by distributed photovoltaic power system(PV)are generally connected into distribution network(DN).If PV is connected into DN without constraints,it will cause the problems of over-limit voltage,voltage fluctuation,harmonic pollution,and so on,which will affect the safety and economy of DN operation.Furthermore,PV brought huge challenges to planning,prediction and optimal control of reactive power and voltage of DNs.Thus,the research for the capacity of grid-connected PV is required and the method of reactive power optimization adapted to DNs with PV needs to be proposed in order to guide the reasonable planning and application of PV.Based on the above,the topic of this article is: Limit Capacity Evaluation of Photovoltaic Generations and Research on Extended Reactive Power Optimization in DNs.The main target of this article is to study the limit capacity of PV that can be accepted by DN and provide the method of extended reactive power optimization,which is based on the mechanism analysis of the influence that PV has on the reactive power flow,voltage and power loss of DN.The main research contents of this paper are as followed:(1)study the mechanism of effect of PV on the voltage,current and power loss in DNs,and reveal the problems that PV may bring to DNs with high penetration;(2)analyze the influence that characteristic parameters of lines have on limit capacity of grid-connected PV under voltage,current and power loss constraints,and propose the method to calculate the limit capacity of PV under the voltage constraints in 10 kV DNs;(3)Combining the application of energy storage system in DNs,the method of extended reactive power optimization adapted to the reactive power and voltage characteristics of DNs with PV is provided.