Theoretical Analysis And Strategies Towards The Interconnection Lines Power Vacancy In China

With the rapid development of economy, the load of the Zhujiang triangle area as one of the big three city urban areas is increasing, and is in demand of huge amount of power electricity. Due to the Zhujiang triangle area is a relatively economically developed area, and also is poor in water and mineral resources, the energy has to be imported from other western provinces which are rich in these. So the situation of the Zhujiang triangle area of Guangdong province receiving the electricity supply from western provinces such as Guangxi, Guizhou, Yunnan, in China Southern Power Grid has been formed. To feed the needs of long distance transmission, many HVDC projects are gradually construceted or planed. So the China Southern Power Grid has become a Multi-Feed AC-DC system. The transmission capacity of these interconnection lines is quite large, e.g. the largest capacity of the line is reaching 5000MW. So the fault of these transmission lines is a serious trouble, which threatened the safty of the power system. In short we should study the fault of interconnection lines in detail which can cause the power supply vacancy, and propose some useful strategies.Firstly the author introduced the simulation environment, the NETOMAC which is the product of SIEMENS AG., and also introduced the models of the data, such as electric motor, exciter, HVDC lines, and load.Secondly the author researched the influences caused by the fault of interconnection lines to the system when using the different load model. Studied the influences of choosing the different load models to the dynamic process and described the dynamic process after the fault.Thirdly from the angle of saving the economic loss and enhancing the system stability, the author proposed several strategies upon the fault respectively from three aspects as generating side, receiving side and HVDC transmission lines. In detail, the strategy of generating side is generator tripping, strategy of the receiving side is Var compensation both using STATCOM and reserve the filter of the DC fault line at converter station, while the strategies of HVDC lines are power emergency support and damping. And the author researched every strategy in detail. e.g. research on the relationships between ratio and duration of emergency power support, the starting time of emergency power support, choosing the lines to have emergency power support, choosing the lines to have power damping, the relationships between poweremergency support and damping and compare the effect of STATCOM and reserve the filter of the DC fault line at converter station.Finaly the author integrated and optimized the former strategies, proposed a strategy of emergency power support corporate with Var compensation at the receiveing side to decrease the generator tripping capacity. Using this strategy the generator tripping capacity after the fault can be greatly reduced or even avoided. So finally the economic loss is reduced and the system stability is guaranteed.