A Comprehensive Suppression Scheme for Subsynchronous Torsional Vibration of Multiple Units under Multi-mode

With the gradual implementation of China's energy development strategic plan, a large number of coal power integration bases have been built and put into operation in recent 10 years, and series compensation capacitor in long-distance high-voltage AC or HVDC transmission has been adopted, which has brought about subsynchronous oscillation problem along with huge economic benefits. To solve the problem of subsynchronous oscillation and ensure the safe and stable operation of steam turbine generator units and power system is a challenging topic in the world. The shafting of a type of turbine generator unit usually has 3 ~ 4 natural torsional vibration frequencies. When the type of turbine generator unit increases in the system, the natural torsional vibration frequency also increases exponentially. Different natural torsional vibration frequencies have different coupling degrees with the electrical resonance of the series compensated output system, which leads to more complicated SSR. Taking the output system of series compensation after the expansion of Jinjie power plant as an example, the analysis and calculation are carried out, and the engineering application scheme of subsynchronous torsional vibration suppression of each unit shafting under multi model and multi-mode is proposed.