Adaptive Direct Output Voltage Control of STATCOM for Dynamic Voltage Support

In this paper, an adaptive decoupled direct-output-voltage (DOV) control strategy of static synchronous compensator (STATCOM) for power transmission system is proposed. The DOV control system is based on the power balance principle, and is feedforward decoupled to cancel out the interactions between the reference active and reactive currents that are produced by the AC and DC voltage regulators. The proposed control increases the response speed of STATCOM and minimizes the voltage overshoot during the response. To make the proposed control system suitable for maintaining the Point of Common Coupling (PCC) voltage under unpredictable disturbances such as fault, load reduction or topology change of the power transmission system, two adaptive PI controllers based on the MIT rule (Massachusetts Institute of Technology rule: parameter adjustment mechanism) are developed for AC and DC voltage regulators. The performance of the proposed controller is validated through simulation results using a 500 kV transmission system.