On-line hydrogenerator power angle and synchronous reactances determination based on air gap measurement

This paper presents a method for the power angle determination of the salient-pole synchronous machine from the terminal voltage and air gap measurement. The method is developed as a part of a monitoring system that is installed on the 26 MVA generator of the Peruca hydroelectric power plant in Croatia. The raw signal of the air gap sensor is used to detect the rotor displacement referenced to the fundamental component of the terminal voltage. The method is proved by comparing it to another measurement of the generator power angle based on a tooth gear mounted on the rotor shaft. In addition, the on-line determination of the synchronous reactances in the q- and d-axis was performed and saturation effects were also considered.