Online Identification of Low Frequency Oscillations Based on Reactive Compensation Switchings

An on-line identification method for the low frequency oscillation based on the reactive compensation switchings is presented in this paper. The idea is to use the reactive compensation switching in the substations or the converter stations to activate the critical oscillation modes, which can then be used for the on-line monitoring and the early warning of the low frequency oscillation. The proposed technique can estimate most of the critical modes in a near-real-time manner. Compared with the traditional methods, the proposed method can avoid the misjudgement of the damping ratios under the forced oscillations. The field test results from Zhejiang Power Grid prove the effectiveness of the method.