Research On Small-signal Stability Of Wind And Photovoltaic Power Generation System

In recent years, with the continuous depletion of fossil energy and the increasing deterioration of the natural environment, renewable energy has been attached more and more importance to. As an important part of utilization of renewable energy, power generation of renewable energy developed quickly, among which, wind and photovoltaic power generation are the most mature technology.With the increasing capacity of wind and photovoltaic power generation, the small-signal stability arises from which has been pay attention to, and become an important research direction.Because of the instability of wind and solar energy, wind generators and photovoltaic cells are often connected to power grid or loads using power electronics converters, and which makes their mathematical model and operation performance are different from synchronous generator, so it's necessary to research the small-signal stability of wind and photovoltaic power generation.It can be started from the small-signal stability of One-Machine Infinite-Bus (OMIB) system to carry out these researches. So, firstly, the small-signal models of OMIB system of wind and photovoltaic power generation are built, detailed derivation of the models are given, and the expressions of the state matrix elements are obtained. The modes and damping characteristics of the system are analyzed by eigenvalue, and the origins of the modes are obtained by participation factors analysis. The system parameters are well designed through the eigenvalue traces. The simulation models based on MATLAB/SIMULINK are presented, and the simulation results show that the system dynamic responses are consistent with the result of small-signal analysis, thus the small-signal modeling and analysis are verified.Then, the small-signal stability of microgrid composed of wind generator, photovoltaic cells, storage battery and loads are analyzed. The small-signal stability model of the microgrid is built. Detailed derivation of the models is given, and the expression of the state matrix is obtained. The modes and damping characteristics of the system are analyzed by eigenvalue, and the origins of the modes are obtained by participation factors analysis. The system parameters are well designed through the eigenvalue traces. The simulation models based on MATLAB/SIMULINK are presented. The simulation results show that the small-signal modeling and analysis are correct.Based on the analysis of OMIB system, the small-signal stability of wind farm connected to the power system is studied further. Small-signal model of the system is built, detailed derivation of the model is given, and the expression of the state matrix is obtained. The influences of different kinds of wind generators and different connected lacations of wind farm on original oscillation modes and damping characteristics are analyzed. Aiming at the influence of the wind farm on the small-signal stability of power system, the stability control method of wind generator is analyzed, and proper parameters of stability controller are designed according to the eigenvalue traces. The Dampings of the oscillation modes are improved, which shows that the stability controller is useful.