| Thyristor Controlled Series Capacitor (TCSC) is an important member of the Flexible AC Transmission System family. It can regulate impedance smoothly over a wide range by changing the firing angle of thyristor. Impedance control is the most fundamental control function of TCSC. The power flow control and transient stability control of power system are implemented through the impedance control of TCSC.The study background of this thesis is the application and implementation of YiFeng TCSC Project, which is the national science-technology demonstration project. The impedance control method of practical TCSC project is simulated and tested. The main research works include the following aspects:1) The impedance control methods and principles of TCSC are analyzed. On this basis, a composite closed-loop impedance control method of TCSC using impedance correction is proposed. By comparing the influence on impedance characteristics of synchronization signal, open-loop control, composite closed-loop control, the thesis points out that the composite closed-loop impedance control method of TCSC using impedance correction shows better steady characteristics, transient characteristics and control robustness.2) The impedance controllers of TCSC are designed, including measuring unit, control unit, TFR unit and monitoring unit. The function, hardware structure and software design of these units are discussed.3) A small experimental model of TCSC is built. The proposed method of TCSC impedance control and the TCSC impedance controller are tested on the model. The experimental results and the simulation results are compared, and the differences between them are explained. Also the influence of quality factor of TCR reactor on the TCSC fundamental impedance is studied.4) The YiFeng TCSC equipment is tested. The test results showed that the designed controller had good performance on TCSC impedance. With composite closed-loop control, YiFeng TCSC exhibits SSO damping in the power system. |
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