Direct approach to optimize PID controller parameters of hydropower plants

As a core component of hydroturbine regulating systems (HTRS), a PID controller is essential to ensure system stability and regulate quality, although its parameter selection remains challenging. This study presents a state space model of an HTRS with a surge tank, as well as an explicit formula derived for the dimensionless turbine rotating speed, using system decoupling with the state matrix in the Jordan ca-nonical form. The regulating quality parameters (RQPs) in the entire stable domain can be readily ob-tained using the direct solving method (DSM) without time-domain simulation, and the optimized PID controller parameters can be selected based on the RQP. A comparative analysis of the DSM and a traditional time-domain simulation was conducted based on a practical hydropower plant. Both methods yielded the same results; the DSM was considerably more efficient in providing the full RQP domain, where the effect of the surge tank subsystem was clearly demonstrated. In the proposed DSM, only state parameters were required for selecting the PID controller parameters. As hydropower plants operate under varying conditions, the DSM was effective for tuning purposes. (c) 2021 Published by Elsevier Ltd.

Automated summary

This study proposes a control method for hydroturbine regulating systems based on a state space model, where regulating quality parameters can be readily obtained using the direct solving method and the optimized PID controller parameters selected based on these parameters. In practical applications, the DSM method is more efficient than traditional time-domain simulation and can clearly demonstrate the impact of surge tank subsystems.