Reasearch On Voltage And Reactive Power Comprehensive Control Method In District Grid With Distributed Generation

This project is the main component of the science and technology project ?Research on Key Technology of Voltage Stability and Reactive Power Control in Distribution Power Distribution Network?,hosted by Shanxi Electric Power Company.Distributed power connected to distribution network will bring great changes in voltage to both PCC point and even entire line.The reactive power of the distributed power supply also affects the traditional reactive power compensation.This paper has carried on the theoretical analysis and the simulation experiment to the distribution network voltage and reactive power effects with the distributed power supply.Aiming at the fluctuation of distributed power output,a static var generator(SVG)is introduced to compensate reactive power and stable voltage.Finally,by analyzing the probability model of distributed power output,this paper gives a comprehensive optimization configuration of SVG and compensating capacitor.Through the simulation analysis and research,the method of optimizing the grid voltage and reactive power under high DG permeability is given.At first,this paper introduces the traditional distribution network power flow calculation method of distributed generation and points out its shortcomings.Based on analysis of distribution network power flow,the definition of a distributed slack bus is given.etermining the participation factor of DG in power flow calculation.Contrast with the traditional power flow algorithm,the number of iterations of the method did not increase significantly,and convergence is still good.The results of the power flow calculation can well reflect the output of the distributed slack bus.The effect has been greatly improved compared with the traditional method.Through the analysis of the influence mechanism of distributed power supply,and then use the proposed power flow calculation method to simulate the distribution network voltage and network loss of distributed power supply with different capacity,different position and different power factor.The results show that the distributed power supply can play a reasonable role in supporting the voltage and reduce the loss of the network.However,with the continuous improvement of its permeability,it will bring some significant effects such as the power flow backwards and voltage exceeding the limits.DG output uncertainty and the impact of the grid off the net also has brought challenges to the distribution network operation control.Secondly,For the impact of distributed power supply,this paper proposed the introduction of static var generator(SVG)to compensate reactive power.Aiming at the characteristics of distributed power distribution network,the recurrent neural network is fully approximated to the ability of any complex nonlinear object,and the positive and negative model of the object is constructed.By recursively the feedback signal generated by the internal model,The SVG recurrent neural network internal model control strategy(IMC-RNN)is designed and implemented.The simulation results show that the control strategy can compensate the various load types well and can suppress the fluctuation of the distributed power supply and have good performance.Finally,in order to improve the transient power quality and the better performance of SVG,this paper analyzes the probability output model of wind power generator and Photovoltaic.Then converting the timing fluctuation of wind power generator output into the probability distribution model of output power.Then,the SVG and capacitor joint optimization model based on the probability output of the wind turbine are proposed.The goal of optimization is to minimize network loss and the optimal investment of the network,meanwhile the voltage stability index(VSI)is the best.In order to solve the multi-objective optimization problem,the Multi-objective Particle Swarm Optimization Based on Pareto Optimal is proposed.The results show that through the rational configuration of DG and SVG,their function will get the best play.This method has a good application prospect.