Study On Evaluation Method Of Transmission Line Utilization Based On Probability Power Flow

Accurate evaluation of transmission line utilization is of great significance to power network planning and operation.With the large-scale interconnection of renewable energy represented by solar energy and wind energy,it brings unprecedented challenges and difficulties to the evaluation of transmission line utilization.In this paper,a probabilistic method is used to comprehensively consider the influence of uncertain factors such as the fluctuation of renewable energy and random load on the grid planning and operation,and to evaluate the utilization of transmission lines based on the probabilistic power flow.In order to solve this problem,this paper carries out related work based on Monte Carlo simulation probability flow,conditional probability theory,comprehensive evaluation decision method and so on,on the basis of extensive review of relevant literature.Firstly,the basic theory,model and method of probability flow are summarized,and the basic principle,calculation steps and precision analysis of Monte Carlo simulation method are described in detail.Secondly,for load uncertainty,the load probability model based on classical distribution and nonparametric kernel density estimation is compared and studied.Thirdly,in view of the uncertainty of photovoltaic output,combined with the characteristics of photovoltaic output and the shortcomings of the existing single-variable kernel density estimation models,a photovoltaic output probability model based on conditional probability and two-variable kernel density estimation is proposed.On this basis,aiming at the problems existing in the time series sampling of photovoltaic output,a random sampling model of photovoltaic time series based on rounding sampling method was established.Then,aiming at the evaluation of transmission line utilization,a comprehensive evaluation index system and its evaluation method covering the power supply line,the main grid line and the load feed and supply line are constructed.Finally,the IEEE39 node system data is simulated and calculated using MATLAB software,and the results verify the effectiveness and feasibility of the model and method presented in this paper.