Locating Generators Causing Forced Oscillations Based on System Identification Techniques

This paper presents a method to locate the source of forced oscillations in power grids caused by maloperation of turbine-governor systems. The transfer function between the grid frequency and the output active power is first estimated for each generator in normal operation condition. The turbine-governor acting as the source of the forced oscillations is then detected by identifying rather large mismatches between the predicted output of its estimated transfer function and actual measurements from the grid. The proposed approach can locate both single and concurrent sources of forced oscillations. The method requires synchronized measurements of the grid frequency and the active power of the generator, preferably from PMU measurements. Results from simulations of the Nordic 44 grid model, which emulates the Nordic power system, demonstrate the validity of the proposed method.