The Research On Network Equivalence Concentrated With Large Scale Wind Farms

Wind power generation has become the most mature and rapidly growing clean renewable energy generation technology, induced by the requirements of the energy and environment. Grid-connected wind power generation has developed rapidly in the past 20 years. With the wind turbine generator capacity and the scale of wind farm increasing, wind power brings inevitable impact to the power system. The existing equivalent method is no longer applicable for dealing with the external network, which concentrated with the large-scale wind farms. Therefore the research on the network equivalence concentrated with large scale wind farms has important theoretical and practical value.The domestic and international research status on network equivalence is summarized in this paper, on this basis, main tasks are as follows:(1) Doubly fed induction generator and its control system are deduced. Doubly fed induction generator operating mechanism is deeply studied.(2) Coherency Equivalent of the network, which concentrated with large scale wind farms, is studied. Coherency equivalent network concentrated with large scale wind farms is accomplished from 4 aspects, such as coherency identification, coherency buses aggregation, coherency generators parameter aggregation and network simplification. A weighing method based approach for parameter aggregation of model of coherent unit groups used to arriving at parameter aggregation of equivalent model of groups of coherent wind farms is proposed.(3) 4 plans for calculating equivalent wind capacity is put forward in this paper, such as according to weighted average efficiency, average efficiency, maximum efficiency and minimum efficient.(4) The accuracy of the equivalent method proposed in this paper is verified by simulation.(5) The sphere of application of the method proposed in this paper is discussed. The conclusion, that simulation accuracy is improved when wind power capacity is larger than 4%, is put forward.