Research On Voltage Stability Of Regional Power Grid With Wind Farm Based On Bifurcation Theory

With the significant growth in wind power generation, the installed capacity is increasing every year. Therefore, the energy penetration of wind in the future power system will be increased, and at the same time, it will take the place of the conventional generators. Thus, the stability of the whole power system will be affected. It has been a hot issue recently on the research of the system stability under the impact of high penetration of wind power generation.The investigation of the dynamic stability of power system plays a great importance role to the safety of the grid. The conventional calculation method of voltage stability and calculation method of voltage stability based on bifurcation theory was compared in this paper. Based on the three nodes system, the system equilibrium solution manifold was solved. The manifold on the static and dynamic Hopf bifurcation were searched. The stable and unstable operation section on the solution manifolds were distinguished according to the calculation of phase diagram. The bifurcation theory method is more accuracy and superiority compared with the conventional method.Voltage stability including wind power system was studied based on the double and single parameter bifurcation analysis method. A regional Northeast power grid was calculated as an example with the establishment of double-fed wind generator model and comprehensive model of dynamic load (Walve model). Bifurcation boundary was obtained with the control parameters of wind generator input torque and load active power, the upper and lower limit of voltage stability margin was calculated. The affect of the dual control variables on the bifurcation boundary are analyzed in-depth. Results showed that: With the increase of input torque and load active power, voltage bifurcation boundary decreases and then increases. When the input torque increases, the load area should avoid the increase in power. With the increase of control variables, these two parameters alternately play a dominant role to affect the bifurcation boundary. Finally, this thesis developed power system voltage stability prediction and early warning technology, containing wind farm, based on synchronized phase measurement unit ( PMU ). Real-time data from the wind farm and network were collected and stability of the system was evaluated. Considering the wind fluctuation and intermittent characteristics, the device is valid at a constant power and variable power factor of wind farm. The device also predicts the power grid voltage stability under the occurrence of transient fault case.