Study On The Design Optimization Of 110kV Substation Grounding Grid Based On CDEGS

The security of power substation has become a hot topic.When it comes to safety in substations,we have to talk about the grounding system.The main function of the grounding system is to avoid the influence of over-voltage on the power equipment in the substation.When the grounding fault or lightning fault occurs,it plays the role of current dissipation and voltage sharing,and meets the safe and stable operation requirements of the power equipment and power system.In addition,the grounding system can also avoid the workers from being hurt by step voltage and contact voltage.For the power system,the reasonable and scientific design of the grounding grid,and in-depth optimization and improvement has a very important practical value.But now the design and optimization of the grounding grid are facing some difficulties.For example,the current power system scale is relatively large,once a short circuit occurs,the short-circuit grounding current is also relatively large,which requires further improvement of the short-time dissipation capacity of the grounding grid;because of the increasing difficulty of land acquisition,most of the new substations are planned in mountainous or hilly areas,under this ground condition,the soil resistivity is large,which brings higher difficulties to the design and optimization of the grounding grid Degree.The substation grounding grid is composed of horizontal and vertical grounding electrodes which are staggered,coordinated and promoted with each other.Among them,the horizontal grounding electrode is the main dissipation channel.When the substation is short-circuit fault or suffered from lightning stroke,the horizontal grounding electrode can disperse the short-circuit current into the earth;while the vertical grounding electrode is an auxiliary grounding measure,which can assist the horizontal grounding electrode to disperse the current faster and better,and can also eliminate the adverse effects of seasonal factors and weather factors on the horizontal grounding grid.They cooperate and support each other to play a role in the effective dissipation of the grounding grid.According to the research results,at present,the safety risk of grounding grid is higher and higher,and the design method mainly adopts the traditional methods such as empirical formula.Due to the high soil resistivity and higher safety requirements of the new substation,the previous design concept can not meet the needs of the current actual situation.In view of the above problems,the CDEGS grounding grid design software is introduced,and the method of theoretical analysis and simulation calculation is adopted.Taking the110 k V grounding grid design optimization as an example,the more accurate,more convenient and faster grounding grid optimization design is carried out.At the same time,the optimization design method and effect of horizontal and vertical grounding poles are studied in depth,which can be applied to engineering practice Conclusion.For example,increasing the surface soil resistivity is an important factor to reduce the contact voltage and step voltage;when the grounding resistance does not meet the requirements,it is the most economical way to use the horizontal additional grounding electrode to lead the grounding grid outside,which should be given priority when the construction conditions permit;the excessive use of vertical grounding electrode,while consuming a lot of resources,cannot effectively reduce the grounding Grounding resistance: the horizontal grounding grid should not be arranged too closely(for example,5m spacing),which is mainly to improve the voltage sharing effect of the grounding grid,and has limited effect on reducing the grounding resistance.The above conclusions can provide support and guidance for the design optimization of 110 k V grounding grid.