Study On Distribution Network Risk Assessment With Distributed Power Supply

Distribution network is an important public infrastructure of our national economy and social development, which is in the end of power system and closely links to customers, and its reliability and power quality is directly affected by the system operation manner. When a fault takes place in the distribution network, users will be seriously affected, hence, it is of great significance to improve operation reliability of the distribution network and reduce the system risk. In recent years, the distributed generation has been extensively applied as a kind of clear and sustainable energy, which can restore partial load due to the fault and thus decrease risk of the distributed supply. Moreover, the traditional risk assessment model, method and index system are not suitable, because the output power of distributed generation holds random and fluctuant characteristics. As a result, the dissertation focuses on risk assessment of the distribution network with distributed generation. The main work is as follows:1. A modified multi-scene output power model is proposed for the distributed generation. On basis of the traditional output power model of distributed generation, the Latin Hypercube Sampling method is applied to digitally discrete the cumulative probability function of the output power of distributed generation, the Simultaneous Backward Reduction scenes is further employed to decrease the number of multi-scene and thus reduce the calculating quantity, and then the multi-scene output power model of distributed generation is established.2. A reliability model is further established for the distribution network with distributed generation, when a fault occurs in the distribution network, the islanding scheme method is firstly analyzed, and the intentional islanding scheme model is proposed for realizing the goal of maximizing the equivalent load, and then the reliability model of the distribution network with distributed generation is established, such that the traditional minimal path is improved, which can be applied to study the reliability of distribution network with distributed generation.3. An assessment system for the distribution network with distributed generation is proposed by analyzing the risk assessment of the traditional distribution network. The traditional security risk index is modified by considering the impact of distributed generation on the distribution network, a new index system of the distribution network with distributed generation is thus established, and the risk index range and expected number is calculated, such that the corresponding risk grading standard is set up and the risk level is assessed.