Enhancement of power system transient stability and voltage regulation performance with decentralized synergetic TCSC controller

In this paper, a new nonlinear control approach for thyristor-controlled series capacitors (TCSCs) has been proposed to schedule TCSC line active power transfer, improving transient stability, and obtain acceptable voltage regulation performance of the power system. This control method for the TSCS has been presented based on synergetic control theory. According to the control targets, a linear combination of the TCSC voltage variation, generator rotor speed, TCSC active power, and TCSC reactance is chosen to design a decentralized synergetic TCSC controller (DSTC). A dynamic parameter adaption approach is also presented for updating the DSTC parameters to satisfy control objectives under different power system operating conditions. In the studied system, each generator is equipped with a decentralized improved synergetic excitation controller (ISEC). Dynamic characteristic of the presented DSTC is studied in a single machine infinitive bus and a WSCC-type 3-machine 9bus power system. A restructured improved synergetic excitation controller (RISEC) has also been formulated to investigate the impact of ISEC on the multi-machine system. Simulation results show that the proposed controller can provide better transient stability, active power flow of the TCSC line, and voltage regulation performance than the ISEC with or without conventional TCSC controller and conventional power system stabilizer without any TCSC controller.