Stability Enhancement Strategy Based on An Improved OSG Method for High-Speed Train-Network System

Low-frequency oscillation (LFO) threatens the safe and stability operation of the electric multiple units(EMUs). The dynamic performance of the second-order generalized integrator (SOGI) and phase-locked loop (PLL) may aggravate the issue of LFO. To address this, an improved orthogonal signal generator (OSG) method is proposed to enhance dynamic performance and system stability. In this method, the dq-frame impedance model of the high-speed train-network(HSTN) system including the SOGI and the PLL is first provided. Following that, the generalized Nyquist criterion (GNC) is used to analyze the stability of the HSTN system. Accordingly, an improved OSG method is used to replace the SOGI, and hence ensures system stability. Simulations are performed to verify the effectiveness of the proposed method.