Design and implementation of a redundant control system for variable speed hydro generators

Abstract

Hydro plant control system (HPCS) has gained a high level of attention in recent years because of their flexibility, reliability, and easy-to-use. This paper analyzes the performance of a 250 MW doubly-fed induction machine (DFIM) under different speed sensor faults (omission, gain, and saturation) that will clarify the need for technically feasible redundancy. The control redundancy, which consists of fault detection, speed estimation, and reconfiguration circuit, is implemented to enhance the permanence and reliability of the DFIM. The logic-based fault detection technique is implemented to detect the speed sensor fault. A second-order sliding mode controller (SOSMC) based model reference adaptive system (MRAS) estimator is implemented to estimate the rotor speed. The proposed redundancy circuit is modeled for a 250 MW hydrogenerating unit using the MATLAB/Simulink environment. It is observed that the proposed redundancy circuit is robust against uncertainty in the machine parameters. Experimental validation is performed in a scaled-down laboratory prototype. The simulation and experimental results demonstrate the efficacy of the proposed redundancy circuit. Fault detection and reconfiguration of the control redundancy circuit are performed within 20 ms.