Influence Of The Wind Power Generation To The Power Network Protection And Automatic Devices

With the development of human society, the energy shortage has become animportant problem that human beings can not be ignored. The current grid exists withthe form of centralized large power grids, but this form of the grid can not timelytrack changes of the network load. The large power grids combined with distributedgeneration is a effective method to improve system security and flexibility. Theintroduction of distributed generation makes the original simple single power supplysystem into a complex, multi-power supply system, that changes the trend of thepower flow, and changes the short circuit current and voltage of the point of failure.Above all, it has a negative influence to the original protection and automatic devices.In analysis of the impact on the network protection and automatic devices,according to the different access location of wind power farms, the paper classifiesdifferent effects on the short-circuit current. The paper makes a wind power farm inTianjin as a simulation example, establishes an accurate model of the wind powergeneration and the network structure by Digsilent. This paper analyses selectivity,reliability, and sensitivity of the distance protection and zero-sequence protection,which shows misstripping or maloperation issues that may arise in failure.On automatic devices, the paper analyzes the shortcomings of the emergencypowersupply autorestart with distributed generation, and research the change of impulsevoltage and current, especially with large capacity motor load. It verifies that thetraditional emergency power supply autorestart with distributed generation has greatlimitations. Based on the above, this paper brings up the fast-transfer method ofemergency power supply autorestart with the wind power farm. For the methods,emulating changes of the motor voltage and speed, and wind turbines speed in thesefour switching mode: fast-transfer switching, capture the synchronization, the residualvoltage switching and loss voltage-starting, the results show that the method canavoid the adverse effects to a certain extent and improve the success rate of theswitching.