A decentralized emergency control scheme for power System transient stability enhancement based on model predictive control

This paper proposes an emergency control scheme based on decentralized model predictive control (MPC) to prevent transient instabilities occurring in power systems. After an onset of transient instability due to a contingency, the control scheme acts on the intercept valves of the steam turbines and the excitation systems of the generators that are available for stabilizing the system. Using the proposed method, the system's operational constraints as well as the turbine actuator dynamics are properly taken into account, and an objective function towards stabilization is minimized at every sampling time to generate an optimal control law. The method encompasses a decentralized control strategy allowing a straightforward implementation that does not require a communication system, nor does it suffer from its inherent delays, where each participating generator unit is equipped with an MPC controller that relies on only local measurements. Following a critical contingency, the controllers force the generators to remain in synchronism and bring the system back to a stable operating condition. The performance and efficacy of the proposed method have been evaluated and demonstrated by simulations performed on two test systems, the WSCC 9-bus and the IEEE 68-bus systems. It has been shown that the controllers, which are designed independently from the contingencies and operating conditions, are effective in restoring the system's stability and are robust even when the system is subjected to structural changes due to integration of power electronics interfaced non-synchronous generator units.