Low frequency oscillation suppression of combined hydropower and wind power generation system

Abstract

The western and southern regions of China are rich in hydropower. In recent years, with the development of wind power, the joint power generation and long-distance transmission of wind and hydropower has become the new normal. Long-distance transmission systems may have low-frequency oscillation (LFO) problems, and at the same time, affected by the hydropower, there may be ultra-low frequency oscillation (ULFO) problems; and affected by the wind power, there may also be sub-synchronous oscillation (SSO) problems. In this case, how to design the oscillation suppressor? There is still a lack of relevant research at home and abroad. This paper firstly designs an LFO controller, and the design goal is to suppress LFO while not deteriorating the oscillation of other frequency bands. Secondly, analysis on amplitude and frequency characteristics of the LFO controller's key links is conducted. Thirdly, the paper constructs a test system for combined wind and hydropower generation system sent to the load center over a long distance, and different mixed proportion scenarios for the combined wind and hydropower generation are considered. Finally, the effect of designed LFO controller is verified by time domain simulations.