Investigation On Impacts Of Integration Of DDPMSG On Power System Rotor Angular Stability

In the process of development and utilization of renewable energy sources, wind power generation is regarded as the most promising one due to it has several outstanding advantages. Moreover, the expansion of the wind power generation will have significant meaning to the transition processes of the sustainable development of both power industry and energy. Direct-driven permanent magnet synchronous generators (DDPMSG) does not have a gear box and the generator rotor is directly driven by the wind turbine which makes the rotation speed low. Furthermore, the operation reliability is improved due to the problems of noise, high outage rate and expensive maintenance fee caused by the existence of a gearbox are solved.Firstly, the background and the importance of wind power generation are introduced in this thesis. In addition, a comprehensive review has been given on the phase locked loop (PLL) which is a vital part of the DDPMSG. After a careful survey has been made on the related research, it is found that the topic of impacts of integration of DDPMSG on power system rotor angular stability has not been investigated thoroughly which is the focus of the paper. Secondly, the principles of the DDPMSG are described in detail in this thesis. Furthermore, the full mathematical model of the DDPMSG is divided into four parts and the corresponding sub-models are introduced. Besides, the principle of the PLL is also presented. In this thesis, three types of PLLS are selected for the performance comparison and study of corrective actions. All the models have been established in the Matlab/Simulink software.Thirdly, simulations of a single machine infinite bus (SMIB) power system integrated with a DDPMSG have been done under different conditions. It is found that the impacts of the DDPMSG on the rotor angular stability of the SMIB power system are different when different types of PLLs are applied. Moreover, the effects of parameter variations of three components of the DDPMSG which are PMSG, voltage source converter and of the PLL on the SMIB power system low frequency oscillations have been investigated when the three phase synchronous PLL is applied. The conclusions are drawn from the simulation results of a two machine power system.