Direct approach to optimize PID controller parameters of hydropower plants

Abstract

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 canonical form. The regulating quality parameters (RQPs) in the entire stable domain can be readily obtained 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.