Research On Reactive Power And Voltage Control Strategy Of Dispersed Wind Power Generation

In recent years,China's wind power industry got very fast development with the support of country.While,with the increasing of wind power installed capacity,wind power eith centralized grid connection is not only required amounts of fund,but also existed difficulties in operation and consumption of wind power.When accelerating the scale development of wind power,our country began to encourage the development of dispersed wind power.The dispersed wind power is single wind turbine or small wind farm distributed in the distribution network in the form of dispersed power.It is small-scale,with the electric energy input into the distribution network directly then used locally.The distributed wind power can solve the problem of centralized grid electricity without long distance transmission.First,in view of the goal of reactive power maximization,this paper proposes a control strategy with the maximum utilization of the reactive power adjustment ability of wind turbines.With the temporarily sacrifice of maximum wind power tracking,seeking the relationship among wind speed,rotor speed and the maximum of reactive power,then get the rotor speed reference,which can maximum the reactive power of wind turbine.Then control the rotor speed of doubly-fed wind power generator variable in different operation models for the objective of reactive power maximizationSecondly,to seek the reactive power control strategy suitable for dispersed wind power,a hierarchical reactive control framework is put forward,and the control method of each layer is expatiated,including the selection of control node and the estimate method of node voltage,the reactive power reference generation and allocation.Finally,the strategies above are validated in PSCAD digital simulation system.The simulation results show that the variable rotor speed model control strategy of doubly-fed wind power generator for reactive power maximization increased the reactive power output ability of wind turbine effectively,and can use wind turbine's own reactive power capacity for voltage regulation;the modified hierarchical reactive power control strategy is more suitable for distribution network,distributing the reactive power between units reasonably,improve the distribution network voltage effectively.