Research On Stability About Wind Farm Isolated Grid Integration Through HVDC

It brings many adverse effects after large scale concentrated wind farms integrating into the power grid, not only low voltage level, fluctuation of voltage and frequency, but also some serious problems, such as poor system transient stability. Traditional AC transmission mode cannot alleviate the adverse effects brought by integration. Flexible HVDC power transmission is based on voltage source converter with self-commutated characteristics, and adopts Pulse-Width Modulation technology, realizes the decoupling of active and reactive power, which makes it possible to adjust independently and continuously. Thanks to its many advantages, Flexible HVDC power provides a new solution and a technical method for the integration. So, it is of great significance to study on the application of Flexible HVDC power on integration. This paper studies Flexible HVDC power transmission on the application of wind farms integration. First, it summarizes wind power integration guidelines of many countries, and expounds the possibility of large scale wind power integration. Then, it simplifies the mathematical models of Doubly-Fed Induction Generator and Flexible HVDC system by coordinate transformation. After that, it proposes the control strategy for integration. In the end, PSS/E is used as a tool to simulate the isolated power grid in some area in Liaoning province, which verifies the beneficial effects in compensating lacked reactive power in systems dynamically, maintaining system voltage stability and suppressing system frequency fluctuations. This study gives very good reference value for Flexible DC power used in integration in the future.