Optimization Research Of Grounding System About Power Plant And Substation

With the increasing capacity of power system, the short current of grounding systembecome more and more large, at the same time the useful grounding net area become moreand more small, resulted in a growing number of difficulty happens when the groundingparameter need meet the current ground rules. This is the current status of power station andtransformer substation in our country. The purpose of grounding system existing in powerstation and transformer substation is both making sure the safety of operation staff both insideand outside of this two places, and avoid the damage to electrical equipment. Due to currentstatus of grounding system as related before, when the grounding resistance can’t meet thecriterion, how to keep the safety of stuff and equipment become the key point to figure out theproblem existing in grounding system of our power system and transformer substation.Moreover, it is the main component of this paper.Based on the existing issues of our power station and transformer substation, this paper emphasize the rising process of both grounding potential when earth short-circuit current happened at power frequency and local potential when lighting current trend to earth. Moreover, this paper analysis the damage to equipment and staff of these two cases related, and optimize the grounding system against the previous problems. So it proposed a mathematical method forover ground wire and current divider coefficient of cable network. To avoid the damage to equipment and staff from earth short-circuit current happened at power frequency, below optimization have been propounded: the optimized grounding arrangement based on the first equipment, equal potential coupling strategy based on the second cable, shift potential optimization ofgrounding network and potential distribution optimization of special placement. Otherwise, tofigure out the damage from local potential rising and second cable when lighting impact short-circuit happened, it suggested the optimization of impact potential distribution, grounding optimization based on the new second cable, equal potential coupling protected device and lightening-protection equipment. As the previous optimization, we can limit below voltage in save value: the groundingvoltage rising, contact voltage, step voltage，derivation of high potential and induce of lowerpotential. In this case, as long as the design of grounding system is reasonable, it still canensure the security of stuff and equipment even if the target value of grounding parameter isdifficult to meet the requirement.