Research On Fault Ride Through For Permanent Magnet Synchronous Generator Wind Power System

There is growing concern about climate change and energy supply issues. Wind energy has been noted as the most rapidly growing technology in renewable power generation and wind power generation has become an important source of power systems. With the increase of wind farms installed capacity, there is growing interaction between wind power generation and local power network. In order to maintain the stability of the power grid, now grid codes require that wind farms have to fulfill demanding fault ride through (FRT). The type of direct driven permanent magnet synchronous generators (PMSG) has the capability of direct connection with no gearbox, and it has many advantages, such as:low noise, low maintenance costs, etc. The topology structure of un-controlled rectifier+three-cell interleaving parallel boost+two-cell interleaving parallel PWM inverter in the direct drive wind power and its fault ride through technology has been researched in this thesis.Fault ride through capability requirements and wind turbines basic working principle have been detailed studied. The topology structure and its control strategy of wind power has been analyzed, the whole system simulation model has been build up based on the PSCAD/EMTDC software. Simulation results are in good agreement with theoretical analysis, which verify the system model and its control strategy are correct and feasible. And it provides a platform foundation for further research.The dynamic behaviors of PMSG during symmetrical three phase voltage sags, unsymmetrical voltage sags and symmetrical three phase voltage swells have been separately analyzed. According to various types of problems that caused by grid faults, this thesis presents control strategy to solve the problems. The control strategy of solution measures have been demonstrated using PSCAD/EMTDC based simulation.The solution measures presented in this thesis is that control strategy is suitable for voltage faults transient period while grid integration. Simulation results show that the proposed control strategy is effectiveness and efficiency. As a result, the proposed method can effectively improve the direct-driven wind power system FRT capability, that is variable speed wind turbine unit with a PMSG realizes fault ride through.