Contribution to robust control for the regulation of a three-machine parallel system in order to ensure power grid stability

This paper presents a cascade control approach applied to voltage and frequency regulation of a multi-machine power network composed of three synchronous generators and six interconnected nodes. The main objective is to improve system stability under disturbances while guaranteeing steady-state robustness.
The proposed control structure consists of two levels. The local level uses a robust H∞ controller, designed for each generator, to ensure individual voltage and frequency regulation despite parametric uncertainties. The global level aims to suppress inter-machine interactions. It is derived from the overall network equation by treating interactions as a compensating control term subtracted from the global dynamic equations.
System performance is evaluated through simulations in MATLAB/Editor. The results highlight robust stability and robust performance in both transient and steady-state regimes. The proposed controllers prove effective under severe disturbance tests, notably a simulated short circuit, confirming that the cascade scheme can maintain voltage and frequency within acceptable limits.