Abstract:The rapid and accurate reliability assessment technique is critical to the improvement of distribution network operational level. A reliability evaluation method of distribution network based on load classification is proposed in the paper, which uses probabilities and sampling approach to determine the operating state of the system and the place where the fault or failure occurs. The distribution system is divided into different types of loads for analysis, and the functions of network reconfiguration and load transfer are taken into account under the case of distributed generation. This method can effectively simplify the traditional reliability evaluation process and improve the efficiency of analysis. It can be also suitable for the real-time reliability evaluation of the distribution network. The validity of the proposed method is verified by the improved IEEE-RBTS Bus 6 system as an example.

Abstract:With plenty of distributed generators connected to distribution system, island operation can be used as a new fault recovery approach to ensure the power supply of critical loads. A heuristic islanding algorithm based on distance-weight was proposed, taking the maximum recovered critical load as the main target, considering the pact of various operation constraints and uncontrolled loads of the distribution networks, introducing distance-weight which represents the distance between the objective load and the island to find out which load is the nearest to the current island and should be recovered first. The initial island is composed of all the DGs and some branches between them, and then enlarged by merging the nearest load among all the considered loads. Finally, it will get security assessment and be regulated. Simulation results have demonstrated that the proposed algorithm can generate a reasonable islanding scheme after a fault occurs.

Abstract:A distributed generator (Distributed Generator, DG) multi-objective optimization model was established to the distribution network. Minimum power loss cost, distributed power system operating costs and minimum active power loss minimum were taken as the objective functions for the power balance. More restrictions and other constraints, using a weighted linear multi-objective manner, were taken as a single target, and the use of quantum particle swarm optimization helped to achieve the above objectives. IEEE33 node system simulation results show that the optimization of the location and the capacity of DG can effectively reduce the economic costs of the system, improve the distribution network and optimize economic operation.

Abstract:Microgas turbine distributed generation system model with dual PWM converter structure was studied. Permanent magnet synchronous machine side and grid side converters control systems were designed on the basis of the droop characteristics. This control scheme could regulate permanent magnet synchronous machine speed and converter DC voltage. A dynamic model of microgas turbine distributed generation was built with Matlab, and simulations were completed under different load conditions. The result has shown that this model has good stability when the load suddenly changes. Rotor inertia response was introduced into this system, which improved the system′s dynamic quality,so the whole micro system can endure a big load mutation.

Abstract:提出了适用于孤岛运行的微电网三相不平衡潮流计算方法:结合实际,对传统潮流计算方法予以改进,计算中考虑了配电系统各分布式电源的有功、无功控制能力,即电压、频率静态调节特性,考虑了变压器移相角对潮流的影响以及线路参数的相间耦合;算法采用相分量分析,能够应对线路参数三相不平衡、负荷三相不平衡等情况;用牛顿-拉夫逊法求解,易于处理环网结构配电网的潮流计算;不仅能进行三相不平衡潮流分析,还能同时计算出系统的频率.