In this work, we study coordination control and effective deployment of thyristor-controlled series compensation (TCSC) to protect power grids against disruptive disturbances. The power grid consists of flexible alternate current transmission systems (FACTS) devices for regulating power flow, phasor measurement units (PMUs) for detecting system states, and control station for generating the regulation signals. We propose a novel coordination control approach of TCSC devices to change branch impedance and regulate the power flow against unexpected disturbances on buses or branches. More significantly, a numerical method is developed to estimate a gradient vector for generating regulation signals of TCSC devices and reducing computational costs. To describe the degree of power system stress, a performance index is designed based on the error between the desired power flow and actual values. Moreover, technical analysis is presented to ensure the convergence of the proposed coordination control algorithm. Numerical simulations are implemented to substantiate that the coordination control approach can effectively alleviate the stress caused by contingencies on IEEE 24 bus system, as compared to the classic PID control. It is also demonstrated that the deployment of TCSCs can alleviate the system stress greatly by considering both impedance magnitude and active power on branches.
coordination control, power systems, thyristor-controlled series compensation(TCSC), disruptive disturbances