Stabilisation of Time Delay Systems with Nonlinear Disturbances Using Sliding Mode Control

This paper focuses on a class of control systems with delayed states and nonlinear disturbances using sliding mode techniques. Both matched and mismatched uncertainties are considered which are assumed to be bounded by known nonlinear functions. The bounds are used in the control design and analysis to reduce conservatism. A sliding function is designed and a set of sufficient conditions is derived to guarantee the asymptotic stability of the corresponding sliding motion by using the Lyapunov-Razumikhin approach which allows large time varying delay with fast changing rate. A delay dependent sliding mode control is synthesised to drive the system to the sliding surface in finite time and maintain a sliding motion thereafter. Effectiveness of the proposed method is demonstrated via a case study on a continuous stirred tank reactor system

Robust decentralised load frequency control for interconnected time delay power systems using sliding mode techniques

Based on a sliding mode control, a multi-area decentralised load frequency control power system with time-varying delays and non-linear perturbations is designed in this study. Due to the destabilising effect of delay on the global system, it is necessary to design a control system to accommodate vast time delays so as to manage the deviation in frequency and interchange power. By taking advantage of the system structure and disturbance bounds, robustness is improved. A sliding surface is designed, and the stability of the corresponding sliding motion is analysed based on Lyapunov–Razumikhin function. A delay dependent decentralised sliding mode control is synthesised to drive the system to the sliding surface and maintain a sliding motion afterwards. The obtained results are applied to a two-area interconnected power system to demonstrate the effectiveness of the proposed method

Decentralized Sliding Mode LFC for Nonlinear Interconnected Power System with Time Delay

This paper considers a decentralised sliding mode load frequency control (LFC) for multi-area power system with uncertain time-varying parameters and delay. Since delays can exert a destabilizing effect on the overall system, it is necessary to maximize the delay bound in order to regularize the deviation in frequency and tie-line power. Robustness is improved by taking advantage of the system structure and uncertainty bounds. A sliding surface is designed, which guarantees the stability of the sliding motion and the stability of the sliding motion is analyzed based on Lyapunov-Razumikhin function which has a fast changing rate. A delay dependent decentralized sliding mode control is synthesized to drive the system to the sliding surface in finite time, and maintain a sliding motion afterward. The effectiveness of the proposed method is tested via a two-area interconnected power system

Reheat Turbine LFC of Power Systems with Multiple Delays Based on Sliding Mode Techniques

This paper considers the growing effect of reheat turbine delays in a power system with multiple delays and nonlinear disturbance. In order to improve the operating condition of the systems and avoid the destabilizing effects of time delay, a model representation for reheat turbine delay is developed where a multiple delayed nonlinear term is used to describe disturbances. On this basis, an admissible upper bound is provided based on the Lyapunov Razumikhin theorem and an acceptable ultimate bound is calculated for the load disturbance. An improved load frequency sliding mode control (SMC) is synthesized such that the controlled system is uniformly untimately stable even in the presence of time delays and nonlinear disturbances. Effectiveness of the proposed method is tested by simulation via an isolated power system supplying a service load