| The worldwide energy crisis and the environmental pollution have made great contribution to the demands of new energy, especially in the power industry. With the rapid growth of the load, nowadays, the better quality, more safety and reliability of power supply are required. Based on the development and utilization of new energy, DGs(Distributed Generators) technologies become a new hotspot in the power industry. Because the introducing of a large number of DGs, the node type of the power appears PQ, PI, PV, PQ(V). In addition, since the existence of PV nodes and weakly meshed network, the traditional back/forward sweep algorithm is not applicable. So research of back/forward sweep algorithm in radical electric power network has some theoretical significance and value in use.Firstly, the working principle and operation mode of DGs is analyzed. According to the characteristics of DGs when they are connected to the grid, it establish their mathematical models in power flow. Secondly, through theory analyses of the every DGs connection with grid and decide they belong to which kind, and this paper give equivalent processes to different types of DGs. For the PV node, processing method is based on iterative voltage invariance and its active power invariance, in order to solve the PV node injection current. For the ring network, the basic principle is to build loop-opening computing model, and according to the basic principles of the circuit to solve the port injection current analog loop-opening. At last this paper uses back/forward sweep algorithm to calculate power flow and carries out the simulation with IEEE33test system. The simulation data shows that the proposed algorithm will be united to deal with a variety of DGs, and the algorithm has a better convergence and adaptability to the loop network with DGs. Finally, the influence of DGs to voltage and net loss are analyzed and some corresponding measures and countermeasures were put forward. |
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