Calculation of Sub-synchronous Oscillation Probability Based on Inverse Function

Abstract

Wind speed has great impact on sub-synchronous oscillation (SSO) with its stochastic characteristic. Monte Carlo simulation is always applied to get the probability density of SSO damping concerning with stochastic wind speed. Although Monte Carlo simulation can provide comprehensive result of the probability density, the computation burden is also huge. The SSO damping can be reflected by the real part of SSO mode obtained by eigenvalue analysis. Polynomial can be employed to fit the function relationship between wind speed and the real part of SSO mode. As the probability distribution of wind speed obeys Weibull distribution, the probability density and distribution of the real part of SSO mode can be deduced by the probability density of wind speed and the inverse function of polynomial in each monotonous interval. In this paper, the polynomial relationship between wind speed and the real part of SSO mode is built by piecewise probabilistic collocation method (PPCM), and then the probability density and distribution of real part of SSO mode are calculated by Weibull distribution and the polynomials. The correctness of the proposed method is verified by Monte Carlo simulation. It was proved that the proposed method can release the calculation burden efficiently compared with Monte Carlo simulation.