Nonparametric Modeling Of Photovoltaic Output And Voltage Control Strategy Of Distribution Network With Photovoltaic

With the development of photovoltaic(PV)grid connection technology,more and more distributed PV is connected to the distribution network.PV grid connection will not only change the distribution of power flow in the distribution network,the intermittence and randomness of PV output will also cause voltage fluctuation,which leads to the node voltage violations and network loss increase.It is of great significance for enhancing the PV effective accommodation and ensuring the safe and stable operation of the distribution network to explore effective measures to improve the voltage quality of the distribution network under high density PV connection.In this paper,the PV output model is firstly constructed,and then three measures including reactive power optimization,distribution network reconfiguration and source-load interaction are comprehensively applied to improve the voltage quality of distribution network with PV.At first,the influence of solar radiation intensity,ambient temperature and weather type on PV output is investigated,the mechanism of PV grid connection causing distribution network loss and node voltage violations is studied.The influence of different PV grid connection parameters on distribution network voltage and loss is simulated and analyzed.The influence law of PV grid connection on distribution network is obtained.Moreover,aiming at the problems of boundary bias and poor local adaptability in the PV output modeling of nonparametric kernel density estimation,an improved nonparametric kernel density estimation modeling method is proposed by combining the adaptive kernel density estimation with the kernel density estimation based on the pseudo-data method,and the PV output probability distribution model is established.And then the PV output model is simulated and verified by the goodness of fit test and error analysis.The results show that the improved PV output model can not only accurately simulate the random characteristics of PV output,but also eliminate the boundary bias and improve the local adaptability.At last,a comprehensive optimization method is proposed to improve the voltage quality of distribution network with PV by combining reactive power optimization with distribution network reconfiguration.The mathematical model of static and dynamic optimization is established and the objective function is to minimize the total voltage deviation and sum of active power loss in the distribution network with PV.The division method of the reconfiguration period of distribution network and the assignment method of control equipment action permission are given respectively.A linear decreasing weight particle swarm optimization algorithm based on position variance is proposed in order to solve the problem that particle swarm optimization algorithm converges prematurely and easily falls into local optimal solution.And then it applied to the optimization of distribution network with PV.The effect of local interaction between PV and flexible load on distribution network voltage improvement is further studied on the basis of making full use of the distribution network reconfiguration and PV residual capacity to participate in voltage regulation.The interactive relationship between PV and electric heating load is given,and the improvement effect of the interactive mode on the distribution network voltage is compared and analyzed with the electric heating load as the object.