A Measurement-Based SSO Probability Assessment Approach Considering Multiple Uncertainties

Abstract

Sub-synchronous oscillation (SSO) of wind power system has long plagued grid operators and researchers. It is affected by different uncertain factors such as wind speed and its probability assessment is crucial for SSO prevention and emergency control. The black box characteristics of wind turbines impede the precise modelling and stability analysis. Meanwhile, researchers concentrated on the uncertainty of wind speed and ignored the impact of grid strength variation. This paper proposed a measurement-based SSO probability assessment approach considering multiple uncertainties. First, a method is proposed to precisely estimate damping ratios of SSO mode based on measured impedance-frequency curves. Then, probabilistic collocation method (PCM) theory is introduced to construct an approximate function between the damping ratio and multiple uncertain inputs. In SSOs induced by interaction between full power convert of Permanent Magnet Synchronous Generator and weak grid, both wind speed and grid impedance are set as uncertain inputs, while only wind speed is considered in SSOs induced by Doubly Fed Induction Generator. For common truncated distribution in power grid, the significant advantages of PCM over other analytical methods are pointed out. Finally, the efficiency and accuracy of proposed approaches, compared with Monte Carlo and other approaches, are validated by simulation.