In view of such fault of TBM operating in Xinjiang as overheat

burnout and low power factor of the reactive compensation system

the equivalent circuit model under the harmonic is set up through the analysis of local power grid

load type of equipment and the actual measurement data at site. The reason for the failure of the compensation system and the influence of the power grid with a relatively long distribution distance（namely

the weak power grid）on the system harmonics are deduced. The optimization scheme for the reactive power compensation system is proposed based on the analysis result. The operation of the optimized compensation system is stable after being put into use. The analysis and optimization scheme of this fault provides theoretical and design reference for the reactive power compensation system of TBM.