Research On Reactive Power Planning Of Distribution Network Considering Voltage Timing Characteristics And Equipment Selection Configuration

With the rapid development of power system in recent years,the demand for electricity is increasing day by day and the scale of distribution network is expanding constantly.The load structure and load characteristics of distribution network also tend to be complicated.The uncertainty of load brings many challenges to system operation.Reactive power planning of distribution network is the necessary means to ensure the safety,quality and economy of power distribution network,and it needs to adapt to this change actively.Based on the consideration of load randomness and time sequence,this paper studies the problem of optimization of locating and sizing and equipment configuration of distribution network reactive power compensation equipment from the viewpoint of global planning.Firstly,the time sequence probability model of distribution network load is designed.Based on the measured data,the load probability model of each period of time is established by adding the kernel density estimation method of the boundary kernel to describe the randomness and time sequence of distributed wind power and the industrial load comprehensively.Furthermore,the load time sequence probability model is applied to the stochastic power flow calculation based on semi-invariant and Gram-Charlier series,and the information of voltage distribution of distribution network voltage in each period is obtained.Secondly,a voltage quality assessment method for distribution network based on voltage fluctuation characteristics of the whole network is proposed.The amendatory CP95 value is extracted as the basic data of the voltage quality evaluation from the distribution information of voltage distribution in each period.The voltage qualification rate,the node voltage maximum,the node voltage minimum,the node voltage peak and valley,the node voltage Voltage average value of five evaluation indicators,based on efficiency coefficient method and the order of the relationship between the weight of the voltage quality indicators at each time to assess the value.The method is designed to provide the voltage class objective function for the reactive power optimization configuration model,and also supplement and extend the conventional definition of the simple distribution network voltage quality.Then,a two-level multi-objective reactive power optimization method is proposed to consider the voltage quality.The objective function of the three objective function is processed by weighting the line loss rate,voltage quality index and reactive power compensation equipment capacity,and the probability distribution of each node voltage timing is constrained.By inserting the adaptive adjustment operator The improved evolutionary algorithm is used to solve the model.A case study shows that this method can obtain the optimization scheme of the reactive power optimization of the reactive power station of the distribution network and the reactive power optimization of each compensation point,and obtain the obvious effect of voltage quality improvement.Finally,on the basis of the previous part,a method of optimal configuration of reactive power equipment selection based on fuzzy evaluation is proposed.The fixed capacitor,the switching capacitor of the mechanical switch,the static var compensator and their combination are taken as the candidate equipments.Taking the equipment cost and reactive power mismatch area as the two evaluation indexes into consideration,the reactive power equipment selection and capacity ratio Optimization of configuration decision.This part realizes the reoptimization of equipment selection and configuration level in distribution network planning,and can better deal with the status quo of random fluctuation of distribution network running status and maximize the benefit of reactive power planning.