Transient power-angle stability analysis of wind-thermal-combined sending system considering LVRT dynamics of wind turbines

Abstract

In the wind-thermal-combined sending system, low voltage ride through(LVRT) and recovery control of wind turbines may affect the rotor dynamics of thermal power unit, and may induce the first-swing or multi-swing instability. The transient power-angle stability analysis model of the wind-thermal-combined sending system is established to reveal the influence mechanism of wind farm output power on transient power-angle stability of thermal power units. Based on the equal area criterion, the effect of different LVRT depths, LVRT recovery rates, and the wind turbines access locations on the instability pattern and transient stability of power angle are analyzed. Single-machine and multi-machine System simulations verify that increasing LVRT depth and slowing down LVRT recovery rate can enhance the first-swing stability of thermal power unit but increase the risk of its multi-swing instability.