Probabilistic Reliability Evaluation Of Distribution System Containing Distributed Generation

In recent years, with the prominence of energy and environmental issues and thematures of distributed generation technology, more and more distributed generationshave been embedded into distribution network, which has dramatically changed thestructure, operation, and control of distribution system. Distribution system reliabilityassessment is also facing new problems and requirements.On the one hand, the access of distributed generations changes the model ofdistribution network reliability assessment. The network structure shifts from thetraditional model of single power point and radicalized power supply to the model ofmulti-point power supply, and the model of distributed generation and energy storageare added to network elements. The other hand, the access of distributed generationsenhances the uncertainty of distribution network operation and fault handling. Thedistributed generation and load may form islanded operation mode under certainconditions. Therefore, the establishment of a comprehensive and reasonable reliabilityindexes system and reliability assessment method has important significance foraccurately handling the impact distributed generation and reasonable assessment ofthe active distribution network reliability.This paper established the concept of probabilistic reliability of active distributionnetwork, and presented the method of active distribution network probabilisticreliability evaluation based on point estimation method. The main work of this paperis as follows:1. Combined with the traditional distribution network reliability evaluationmethod, the impact of distributed generation to distribution network reliabilityassessment is analyzed. The paper brings the idea that describing the uncertainty ofthe active distribution network reliability with probabilistic distribution of reliabilityindexes;2. On the basis of the timing models of distributed generation and energy storage,the probabilistic models are established by Monte Carlo sampling;3. In the framework of Monte Carlo simulation, the active distribution networkfailed subzone is determined and the probabilistic models of islanding randomvariables are established firstly; then the islanding probabilistic reliability is assessed with a nonlinear transformation method of independent random variables based onpoint estimate method; finally, system probabilistic reliability indexes can be obtainedfrom the probabilistic superimposing of the results of repeating simulated failures,achieving a comprehensive assessment and analysis to the active distribution networkreliability.4. The validity and accuracy of this assessment approach is verified by thesimulation on the transformed multi-branch feeder model of the IEEE RBTS Bus6.