Simultaneously-tuned decentralized control of excitation and STATCOM for voltage regulation and stability enhancement in power systems

This paper investigates the coordinated design of generator excitation and STATCOM controllers to achieve an effective trade-off between voltage regulation and system stability improvement in a single-machine-infinite-bus power system with STATCOM connected at the electrical mid point. Firstly, the authors derived the uniform system model, in which generator´s double-axis dynamics is considered and the voltage-sourced STATCOM is modeled as a one-order low-pass filter. By introducing a linear quadratic performance index, the control designing procedure can then be formulated into an optimization problem. A direct iterative algorithm is proposed next to simultaneously tune the decentralized feedback gains. Finally, digital simulations are fulfilled to verify the effectiveness of the proposed control strategy. Result shows that the power system with the coordinated controllers can obtain good voltage regulation performance as well as satisfactory stability improvement. Furthermore, the resulting controllers are based on local available measurements, which makes it feasible in practical applications