An innovative approach to PID governor upgrade for reaching SFC regulation stability

Abstract Due to the growing number of renewable power sources in electrical grids, there is a need for expanding the number of generating units capable of providing power-frequency ancillary services. Hydropower is emerging as a viable provider of secondary frequency control (SFC) however, many units, esp. those with complex waterway systems, cannot achieve the stability requirements for SFC using conventional PID governors. In the paper, an innovative approach to a PID governor upgrade for a hydropower plant Alpaslan-2 in Turkey is presented. The modelling of the hydraulic system and turbine governor was implemented and tested in the computer software SIMSEN. An upgraded PID governor includes a wicket gate manoeuvring compensation loop, surge tank level oscillation compensation loop, and a feed forward loop. With the improved model, we achieved (in a simulation and on site) a load fluctuation inside the ±1% load range during small and large load reference changes. This allowed the Alpaslan-2 HPP to conform to the Turkish grid SFC and primary frequency control (PFC) requirements.