Variable structure control based active disturbance rejection control of unstable non-minimum phase delayed processes

The standard active disturbance rejection control (ADRC) method does not work for controlling unstable, non-minimum phase delayed systems. To solve this issue, a variable structure control (VSC) based ADRC approach is proposed for controlling unstable non-minimum phase industrial processes in this work. Tuning of control parameters for optimal control performances is accomplished with the particle swarm optimization (PSO) based approach. The performance of the proposed VSC-based ADRC approach is numerically studied on an unstable non-minimum phase (UNMP) process with delay and a u-tube steam generator (UTSG) level control system. It is found that the proposed control method is able to provide a fast response, zero steady-state error, and robustness against process uncertainties and load disturbances.