Research On The Small Signal Stability Of Power System Integrated Wind Farms

As the increasing depletion of coal energy and constantly changing environment, renewable energy such as wind power is becoming an alternative. However, with the penetration of wind energy is becoming higher and higher in power grid, it is very important to investigate the impact of wind generations on stability of grid. This paper mainly studies on the Impact of Large-Scale integrated Wind Farms on the Small Signal Stability of Power System. The main content of this paper are as follow:(1) Firstly, the mechanical system models of wind generator are built, including the aerodynamic model, single mass and tow mass shaft model, pitch control system model and maximum power point tracking model. This paper derives the dynamic equations of doubly fed induction generator and permanent magnet synchronous generator in the rotating dq coordinate. Meanwhile, the models of converts and the control system are established.(2) Secondly, in this paper, the small signal stability of the simple wind power system based on DFIG and PMSG is established. The small signal model of the simple is built, and the status equations are linearized. The eigenvalues and participation factors are calculated to analyze the small signal stability and damping characteristic of low frequency oscillation. The calculation results show that there are oscillation modes and attenuation modes in the simple infinite system based on the two types of wind generators. But all of these oscillation modes have high damping ratio and good damping characteristics. The system is small signal stability. These oscillation modes are mainly associated with the mechanical system and the converter’s control system.(3) At last, this paper builds the models of the actual wind farm based on DFIG and PMSG wind generators. The wind farm model is equivalent reasonably. The different output of the wind farm is used to study the impact of the power system on low frequency oscillation modes and damping characteristic. In order to maintain the power balance of the original system, output of the wind power is accepted by reducing the output power of thermal generators or cutting machines. The simulation results prove that the damping ratios of low frequency oscillation modes are decreasing with the increasing of output power of wind farm.