RT-HIL testing of an excitation control system for oscillation damping using external stabilizing signals

A feature of an Excitation Control System (ECS) for synchronous generators is to enable power system stabilization by providing an additional input to the Automatic Voltage Regulator (AVR) for external stabilization signals. This paper explores this feature by externally generating stabilization signals which are fed as an analog input to a commercial ECS. This allows bypassing the built-in PSS function in the ECS and gives more freedom to the end-user to utilize custom stabilizer models. ABB´s Unitrol 1020 Excitation Control System is coupled with Opal-RT´s eMEGAsim Real-Time simulator to perform Hardware-in-the-Loop simulation of the ECS. The output of several stabilizer models is fed to the ABB´s Unitrol 1020 ECS as external power system stabilization signals to analyze their performance for small signal stability enhancement.