Location and Mechanism Analysis of Oscillation Source in Power Plant

A generation unit that is poorly damped or has periodical mechanical power outputs from its prime mover can become a source of oscillation in a bulk power system. Choosing the proper electric quantity to extract the oscillation characteristics is crucial for the location and mechanism analysis of the oscillation source. This paper proposes the concept of oscillation phasor to characterize a type of sustained power system oscillations that originate from power plants. On this basis, a two-stage scheme is presented to locate one type of the sustained oscillation source and discover its mechanism: first, Prony analysis and the first wave algorithm are applied to extract the oscillation phasors on active power and angular frequency; second, the phase relationships between the oscillation-source generator and other generators are derived to guide the location of the source; finally, damping estimation on these oscillation phasors help distinguish a forced oscillation from a poorly damped oscillation. The proposed scheme is first demonstrated in detail on a two-area four-machine system and then tested using historical oscillation event data.