Multivariable active disturbance rejection control for compression liquid chiller system

The compression liquid chiller system is a strongly nonlinear and multivariable system. How design a suitable control strategy still is a challenging task. This paper proposes a multivariable active disturbance rejection control (ADRC) for a compression liquid chiller system, where the loop coupling is estimated and compensated in real-time by enhanced reduced-order extended state observer (ESO) and static decoupling. Based on the nonlinearity and coupling analyses of the compression liquid chiller system, the reduced-order ESO-based ADRC is developed. Then the stability region of the proposed ADRC is deduced and a practical parameter tuning procedure is summarized in detail. With the application of the proposed ADRC for the compression liquid chiller system, the simulation results illustrate that the proposed control strategy can guarantee satisfactory tracking performance and estimate the loop coupling completely under different operating conditions. The performance of the loop coupling rejection and the fluctuation of the control signal have improved by at least 57.05% and 58.76% under all operating conditions, respectively, compared with the decentralized regular ADRC. The simulation results also show the proposed multivariable ADRC has a promising future for practical systems.

Automated summary

This paper proposes a multivariable active disturbance rejection control (ADRC) for a compression liquid chiller system, where the loop coupling is estimated and compensated in real-time by enhanced reduced-order extended state observer (ESO) and static decoupling. The simulation results illustrate that the proposed control strategy can guarantee satisfactory tracking performance and estimate the loop coupling completely under different operating conditions. Compared with the decentralized regular ADRC, the performance of the loop coupling rejection and the fluctuation of the control signal have improved significantly.