Damping the electromechanical oscillation modes (EOMs) in DFIG-integrated power systems with sensitivity analysis and optimization to outputs of SGs

Abstract

The electromechanical oscillation modes (EOMs) are the oscillations strongly related to the synchronous generators (SGs), which are dangerous to the security of the SGs and the stability of the power system. Integration of the doubly-fed induction generators (DFIGs) causes dynamic interaction among the SGs and the DFIGs, and adds the difficulty to damp the EOMs. This paper proposes a damping scheme to the EOMs based on the sensitivity analysis and the optimization model. The novelties include, 1) The sensitivities of the electromechanical loop participation ratios related to the EOMs are newly given by the sensitivities of the participation factors. 2) Since the participation factors are composed of the eigenvectors, by introducing the magnitude and phase angle constraints, the sensitivity model of the eigenvectors is improved to find the unique solution. 3) Since the bus powers changes the bus voltages and the eigenvalues, but are not shown in the state matrix, the sensitivities of the state matrix with respect to the power outputs of the SGs are derived with the help of the Jacobian matrix in power flow analysis. 4) Based on the sensitivities, an optimization model is proposed to coordinate the outputs of the SGs and damp the EOMs of the power systems. In the numerical analysis, the accuracy of the sensitivity models is verified by comparing with the result from continuous calculation. The optimization effect is verified by the time-domain analysis. It is found that the not only the active power but also the reactive power of the SGs are effective to damp the EOMs.