Ivestigation On Grounding Technology Of Dalian Huachang 220KV Transformer Substation

The substation grounding system is to maintain the power system operate safely and ensure safety for people and devices.220kV voltage systems have the characteristic, such as high voltage, large capacity, heavy ground fault current, in order to ensure safe. so grounding system requirements will be more stringent.At present, China’s presence in the grounding system design meets two major problems. One is that the design is too simple. The other is paying little attention to step voltage and touch voltage. A direct consequence of this design is leading to actual results quite different from the completion of the design, delaying substation construction period, causing huge economic losses. Also it causes that the grounding system reform needs additional funds, land and a range of issues. Therefore, how to design and construct for grounding system in this high soil resistivity, winter thick permafrost regions, make the grounding resistance, step voltage and touch voltage meet the requirements. And it plays a vital important role in ensuring the safety of 220kV system.This paper is based on Dalian Huachang 220kV substation practically and talk about grounding technology research. Firstly, soil structure model is analyzed by field measurements. And huachang substation soil resistivity data is obtained. To reduce the impact of seasonal permafrost grounding system, substation ground grid levels should be buried under the permafrost.Secondly,220kV substation grounding standard is studied by experiment. Through control cables, secondary equipment and communication cables frequency voltage withstand test, the value of the substation ground potential rise is determined, and the value is 5kV. While the safety indicators of the step voltage and contact voltage is analyzed.In addition, the level ground grid of Huachang substation is analyzed. To reduce short-circuit ground potential rise, one method is using lower grounding resistance, the other is using the ground network optimization.Finally, a variety of ground resistance testing methods for measuring 220kV substation grounding system is researched, effective measurement method proposed for 220kV substation grounding resistance grounding system is the use of current and voltage electrode lead with extremely different to the layout.