Study On Protection Problem After STATCOM Access To Power System

Power quality problems serious threat to the security and stability of power system.The development of STATCOM can greatly improve power system voltage stability.Compared with the traditional compensation capacitor.STATCOM with the advantages of fast response,small volume,wide adjustment range,Is the development trend of reactive power compensation,it is also an effective means of solve power quality problems.STATCOM can supply dynamic reactive power compensation for power system.at the same time,the Dynamic and transient of power system also always affect the operation of statcom.When unbalanced fault occurs in the power grid,the protection of STATCOM need to make corresponding control strategy change.And then effectively improve the performance and reliability of STATCOM,avoiding STATCOM out of operation due to failure.In addition,STATCOM access to power grids,its also affect the relay protection of power system In the process of reactive power compensation.Especially the distance protection of the transmission line,because STATCOM will make it measured impedance produce error,Affecting the protection action ratio of the distance protection.To cure the above problems,this paper combined the project of installation STATCOM in Dongguan power grid,research STATCOM connected to the grid related protection problems.When unbalanced fault occurs in the power grid,through the analysis of the causes of STATCOM over current,combining the actual running situation of SHUIXIANG substation statcom,propose the improved methods for suppress converter overcurrent base on the individual phase control,and verify their reliability through simulation.And these questions about statcom affect the distance protection of power system when it access to power grids.Through theory analysis the impact to the distance protection when STATCOM installed in a different location,As an example in 220 kV line calculating model of shuixiang substation,Calculated the related failure quantity by using RelayCAC Relay setting calculation software,to figure out the impedance error percentage of the distance protection,and analyze the range of impacts.