Three-phase Power Flow For The Weakly Meshed Distribution Network With The Distributed Generation

The status of energy and resource in china is very grim. The development model of economy must be decisively transferred from excessive consumption of resource and energy and pollution of the environment to a very thrifty model, which is in harmony with the nature. Distributed generation is a brand-new and promising technology to generate electricity and utilize power comprehensively. Distributed generation includes wind power, solar power, battery, fuel cell and micro turbines, etc. . The development of distributed generation has brought new advantages to traditional power systems, it has also brought challenges including network losses, power flow, voltage, power quality and relay protection, etc. . It is necessary to study power flow for distribution network with distributed generation, because power flow is major tool and basic of analyzing the influence of distributed generation to power system.Traditional balanced power flow algorithms are not applicable to the distribution network with distributed generation because of the unbalance in power source, load and line, so it is necessary to study unbalanced three phase power flow of distribution network. The difference between the models of distributed generations and traditional generations is key to the power flow calculation of distribution network with distributed generation. Generally speaking, traditional generations are viewed as PQ bus, PV bus or balance bus in the power flow calculation. But the model of distributed generation depends on its operation mode and control characteristic. Based on the analysis of wind turbines, photovoltaic system, fuel cell, storage battery, high frequency micro turbines and power frequency combined heat and power (CHP), their models in power flow calculation were presented. Based on the back/forward sweep algorithm in power flow calculation which was widely used for the radial distribution network, a new three phase back/forward sweep power flow calculation for the weakly meshed distribution network with the distributed generation was presented. The example has proved the efficiency and feasibility of the algorithm.