Nonlinear decentralized excitation and governor coordinated control for hydraulic power plants

In this paper, a nonlinear decentralized excitation and governor coordinated controller design for hydraulic power plants is proposed to enhance power system transient stability. First, the excitation system and hydro-governor system, considering non-elastic water hammer effect, is modeled as a whole. Then, based on differential geometric theory, the original nonlinear system for multi machines is exactly linearized by appropriate coordinate transformation. After that, linear optimization control is applied such that the final optimized nonlinear excitation and governor coordinated control law can be obtained. To demonstrate the efficiency and analyze the coordination mechanism of the proposed controller, simulations on an OMIB system and the EPRI-36 system are performed. Comparison with classical excitation and governor control, nonlinear optimal excitation control, nonlinear robust governor control, the suggested decentralized and coordinated control can achieve pretty better performance in improving the transient stability of power systems.