Research On Protection And Coordination Control With Wind Farm Integration

In response to the quick consumption of traditional energy and the destruction of environment, renewable energy has developed swiftly and violently in the world. Wind power has attracted much attention since it has outstanding advantages, such as non-pollution, being renewable and resourceful, quick investment recovery and so on. Large-scale wind power integration can improve the unreasonable energy structure, but it may also cause lots of adverse effects on the power system. This article mainly aims at the influence of DFIG wind farm on phase selectors and the coordination method of battery energy storage system for smoothing wind power fluctuations. Then, preliminary research has been carried out on the coordination of wind farm and gas turbine power plant.Considering characteristics of sequence impedances of DFIG wind farms, an analytical method is used to identify factors affecting phase selectors in wind farm protections. The expressions of sequence impedances after crowbar being applied show that the positive and negative sequence impedances of DFIG are functions of rotor speed and crowbar resistance. Additionally, the hypothesis that the positive and negative sequence impedances of the system are approximately equal does not hold for DFIG wind farms. Furthermore, the reason why phase selection elements based on variation components and sequence components can’t apply to DFIG wind farms is given based on above conclusions. Finally, the results of RTDS simulation demonstrate the validity of these theoretical analyses.To smooth the long-term and short-term wind power fluctuations, a new coordination operation method of battery energy storage system(BESS) based on model predictive control(MPC) and low pass filter(LPF) is proposed in this article. Established on the wind power forecasting results, the receding optimization is utilized to control the BESS every 15 minutes while a number of constraints are considered, such as the smoothing effects of grid-connected power, the state-of-charge(SOC) of the BESS and so on. Furthermore, the connection of MPC and LPF are established by compensating for the traditional LPF to ensure that the SOC could catch up with the optimization track set by MPC. Finally, simulation studies demonstrate that the new method can not only smooth the short-term fluctuations, but also control the SOC in reasonable range in long-term time scales.Finally, preliminary research has been carried out on the coordination of wind farm and gas turbine power plant. This paper gives a brief introduction of combined cycle gas turbine and then a new coordination operation method of wind farm and gas turbine power plant based on mixed integer programming has been proposed. Considering multiple constraints, it aims for the best economy of wind farm and gas turbine power plant.