Research On The Control Strategy Of STATCOM For Wind Farms

With the increasing scarcity of Energy sources and the development ofhigh-power electronics technology and, wind power has got a rapid development inrecent years. When the wind farms export the active power to the grid, it must alsoabsorb the lagging reactive power from the grid, which will reduce the stability of theregional grid that access to wind power. it will not only pollute the power grid, butalso increase the energy loss of the wire and the stability of the grid and so on.Especially when the grid break down,Wind power generation units from the systemneed to absorb a lot of reactive power to complete their own voltage recovery，evenmore, resulting in power shortfall, serious deterioration of the situation of reactivepower, making the regional power grid voltage in a lower level, or even inducedvoltage instability and collapse. Therefore, to determine a good system reactive powercompensation and voltage adjustment programs is necessary for the reliable grid andstable operation of the wind farm.In this paper，there are research in reactive power compensation on STATCOMin the wind farm and capability to ride through system fault and improvement of thesystem output。Then analysis the vector control on positive and negative sequence andReactive power compensation strategy。 finally， the simulation and experimentcertificate the effectiveness of the research。The paper briefly introduces the development of wind farms and its parallel gridoperation and the problems and the meaning of reactive power compensation for thewind power. Then it elaborate the classification,the advantages and disadvantages ofreactive power compensation device, in addition, it analyses the operating conditionunder asymmetric fault. the paper presented a new strategy which respectivelyorientates positive and negative sequence vector.The strategy would implementvector decomposition for asymmetric voltage and current to realize controlscheme-oriented of electric vectors respectively in positive and negative sequencenetwork，which could effectively suppress output harmonics, stabilize DC voltage,and realize dynamic reactive power compensation. Furthermore，Energy dischargedevices were introduced to improve STATCOM which did not run off the networkwhen there were some faults. The new strategy is simple and reliable, high robustness,easy to implement.Simulation results show that the proposed control method can gothrough the faults in time，compensate reactive power effectively and stabilize the DC side voltage。...