Subsynchronous Oscillations Study Of AC/DC Parallel System With Series Capacitor

With the "West-East electricity transmission project" and the gradually-formed market operation of the interconnected power grid region, series capacitor compensation and HVDC are widely used in our country. Field experience and studies show that subsynchronous oscillation (SSO) may be caused by either the connection of HVDC or the addition of series capacitor compensation. When they coexist in an AC/DC system, the SSO problem become complex because of the mutual effect of series capacitor compensation and HVDC. Accurate analysis of the SSO characteristic of this new system and to take effective suppression measures to maintain system stability is important to run. This dissertation devotes itself mainly to the research on subsynchronous oscillation in complex AC/DC power system and to provide resolve schemes of SSO in engineering application.(1) Project status of complex AC/DC power system with series capacitor compensation is introduced. The pervious SSO analysis methods is summarized and the applicability is analyzed.(2) The structure, operation mode and control strategy of thyristor controlled series compensator (TCSC) is studied. Based on the simple system model with TCSC modified from IEEE first benchmark model, SSO suppression mechanism and conditions of TCSC are discussed and common conclusions are derived.(3) Electromagnetic transient model of Yimin-Fengtun/Hulunbeier-Liaoning system is established based on PSCAD/EMTDC platform. And then transient torque time simulation method combine with Fourier analysis method is adopted to analyze this new grid. The advantage and disadvantage of each method including time domain simulation method, complex torque coefficient method and Prony method is compared and prove the effectiveness of each other. The conclusions are benefit to engineering and provide references for the construction of grid...