Research On Risk Assessment In Distribution Network Involving Distributed Generations

Distribution network is the part of the power system which is directly connected tothe users. It undertakes the responsibility to provide stable, reliable, high quality electricpower. Statistics show that80%of power outages were caused by failures in thedistribution network. These sudden power failures of the power system have broughtsignificant losses to the national economy and people’s lives. Therefore, strengtheningof risk assessment and management of the distribution network, and improving thecontinuity and quality of supply power in our country, are both serious and significantwork. With the development of the smart grid, the introduction of distributed generationtechnologies on the one hand can shorten fault recovery time of load power supply,reducing the power losses; on the other hand, the risk analysis model and the assessmentmethods have undergone major changes due to the changes of grid structure and theintermittent, random output of distributed power. This paper studies risk assessment andcontrol method of distribution network with DGs. The main work is as follows:①In this paper, an islands partition strategy is introduced to the risk assessmentprocess to deal with the impact on operation mode of the distribution network from DGswhen the failure occurs. In order to reduce computation time and improve the speed ofrisk assessment, two islanding parameters, contribution index and consumes index, aredefined to weaken the impact of the wiring structure on the computation speed. Basedon these work, this paper presents a fast islands partition algorithm which can meet theassessment accuracy meanwhile effectively reduce the computation time.②To meet the requirement of computation speed in risk assessment process, thispaper adopts the Latin Hypercube Sampling-Monte Carlo Sampling in the process ofsystem state sampling, which has smaller variance and faster convergence. By way ofpartition, sampling, sorting the various system variables, the system status for powerrisk assessment is determined. From the perspective of adequacy, this paper establishesan appropriate outage risk indexes system of distribution network, as well as the riskdegree criteria.③Considering the lack of risk control strategy in traditional risk assessmentprocess, this paper propose an outage risk control strategy of distribution network withDGs based on improved genetic algorithm. By analyzing the economic indicators of riskcontrol, establish the risk control model of distribution network with DGs; solve the risk control model with niche genetic algorithm based on adaptive technology.