Prediction-based super twisting sliding mode load frequency control for multi-area interconnected power systems with state and input time delays using disturbance observer

Abstract

A shift in paradigm from dedicated to open communication channels in power systems has made them prone to constant and time-varying delays. This paper tackles a novel load frequency control (LFC) problem in the presence of constant and time-varying delays in state and control input under load disturbances. The presence of time delays can deteriorate the performance of the controller or even destabilise the system. The above problem is addressed through a prediction-based super twisting sliding mode control (ST-SMC) using a state and disturbance observer. The proposed design achieves finite-time convergence of frequency and tie-line power deviation. The said design is validated under ramp and random step disturbance, with nonlinearities like generation rate constraints and governor deadband, with an integration of renewable energy and also with IEEE 39 bus power system. The closed-loop stability is proven thanks to candidate Lyapunov function and verified by simulations.