Novel strategy for stability control of AC&DC parallel transmission system

Along with the development of projects of power transmission from west to east in China, more power and load centers are connected by high-voltage AC&DC transmission lines, which pose challenges to the operation stability of power system. When a malignant fault takes place in the power system, especially DC faults with heavy power, it is likely to lead to swings and even collapse of the power system. Advanced SSC (Safety and Stability Control Device) equipment are designed at the AC/DC converter station or the focus location of power flow, the devices are linked by the high performance optical fiber commutation network. In the paper, the structure of SSC in China´s Tian-Guang AC and DC parallel transmission system is analyzed, the trigger criterion of SSC is based on the measurement of power, the partial control strategies and some instances are given. It is important and necessary for hybrid power systems to use SSC equipment. Finally one conclusion is drawn about the operation problems and future development of SSC.