Comprehensive Security Evaluation Of Distribution System With Distributed Generations

With the rapid development of renewable energy,a large number of distributed generations is an inevitable trend in the development of the future power system.The access of distributed generation makes the traditional single-power radial distribution network into a new power distribution system with multiple power sources and loads.However,due to the volatility and randomness of distributed power output,the power grid may experience voltage overruns,power flow changes,line overloads,or even load loss,which will inevitably affect the safe operation of the distribution network.Therefore,in order to ensure the orderly access of distributed generation and the safety of the power system,it is very necessary to study the security situation of the distribution network containing distributed generations.This thesis mainly studies and analyzes the security situation of distributed generation connected to the distribution network.This thesis mainly explains the impact of distributed generation on the security situation of the distribution network,and focus on the analysis of the impact of distributed power on voltage fluctuations and network losses,and establishes a more scientific and accurate set based on power supply quality and power supply capacity.An indicator system for the security situation of the distribution network with distributed power sources.To reflect the randomness and volatility of distributed power output,a distributed wind power and photovoltaic output model was established.For a scientific and accurate evaluation,scene clustering was implemented based on the CH+improved K-means method,and typical daily data was obtained.This thesis proposes a comprehensive evaluation method for the security situation of distributed generation connected to the distribution network based on utility theory and evidence-based reasoning algorithms.First,the membership degree of the corresponding index is obtained based on the utility theory method;then,the performance of a single weight is improved by combining the weights of the triangular fuzzy analytic hierarchy process and the entropy weight method,and the index weights are optimized based on the chi-square distance.Finally,based on The evidence reasoning algorithm evaluates the security situation of the distribution network.At last,taking the IEEE33 node system as an example to analyze the security situation of the distribution network with or without distributed generation and electric vehicles,locations,concentration,and typical day conditions.The security situation of distributed generation connected to the distribution network is graded,and the results prove the influence of distributed power sources on the security situation of the distribution network and provide references for the planning of distributed power generation and the safe operation of the distribution network.