TCSC Control Strategy And Its Simulation Analyzation

TCSC can adjust its equivalent reactance flexibly, continuely and smoothly by precisely and fast controlling the thyristor operating angle. TCSC is one kind of mature and widly used technology in the FACTS. TCSC is helpful in improving the transmission capacity, damping power oscillations and increasing the transient stability of the power system.In this paper, we summarized the development history and recent research advances of TCSC. The basic structure, operational principle, fundamental frequency impedance characteristics and its operating characteristic of TCSC have been analyzed and summed up.The steady-state characteristic and transient characteristic of TCSC have been researched. We worked out the steady-state impedance model, analyzed resonance problem and simulated four operating modes of TCSC to study their steady state operational features. After that, we also compared the process of impedance step response in capacitive reactance region, when the synchronized signal of TCSC is capacitive voltage and line current.The change from one kind of impedance to another will lead to violently transient state process, so the research on the swiching time and the dynamic process smoothness of TCSC is of great important. In this paper, we put forward some efficient mode-switching methods.The Fuzzy PID impedance controller of TCSC has been designed based on the fuzzy theory and PID impedance controller. Besides, the Fuzzy Immune PID impedance control method of TCSC, which has immune feedback element, was put forward. The simulation results show that this algorithm has minimum overshoot, short respond time and good tracking performance to all kinds of impetance step functions. And it can basically achieve isochronous control.We analyzed the static and dynamic simulation results of the single-phase and three-phase system with TCSC and without TCSC. From this we can see how TCSC impacts the load voltage and power flow of the electric power system. And the impedance control mode of TCSC was applied in the electric power system, we compared their effect on system operation. The simulation results show that TCSC plays an important role in increasing the transient stability of the electric power system and damping power oscillations. And the impedance control mode of TCSC will remarkably impact its application performance. Compared to the tradditional PID control and fuzzy PID control, the TCSC fuzzy immune PID impedance control elaborated in this paper is the optimal control method.