| The grounding grid is the important facility of the s ubstation,its safety design is the foundation of ensuring the safe operation of the substation.Smart substation is the future development direction of power grid substation.Its relatively high capacity and intelligent primary equipment application make the consideration of grounding parameters in the design and design stage of intelligent substation different from ordinary substation.At present,there is no systematic research on the design standard and design scheme of the grounding grid of intelligent substation at home and abroad.Therefore,it is significant to study the grounding grid of intelligent substation from two aspects: grounding grid design standard and resistance reduction measures.On the basis of the analysis on grounding safety design index and design scheme of 110 k V and 220 k V common whole-indoor substation,The safety design index and design scheme of whole-indoor intelligent substation of the above two voltage level are studied,the main work includes the following sections:(1)The safety design index of the intelligent substation grounding grid should be put on the GPR.By analyzing the different characteristics of intelligent substations relative to ordinary substations,the key points for evaluating the safety of intelligent substation grounding grids are transformed from two aspects of personal safety and equipment safety to safety of equipment,and safety design indexes should be focused on GPR.Based on EMTP simulation software,the process of GPR counteracting low-voltage surge arrester is simulated.The results show that using the capacity of substation low voltage surge arrester to determine the GPR safety limit,we can get a more secure and reliable and not too conservative value.(2)The local pressure mean of bongrace type uniform pressure band and its selection and application in grounding grid are proposed.The bongrace type uniform pressure band in grounding grid is researched using CDEGS software.Results show that the bongrace type uniform pressure band can reduce the grounding of local contact potential difference and step potential difference effect,and it can be used as an auxiliary way of grounding grids are pressed.The shallow burying of the earthing body and the proper increase of the distance between the earthing body can make the local pressure sharing effect better.In the design of the grounding grid general scheme of 110 k V and 220 k V whol e-indoor substation under small fault current,the local contact potential difference of the preliminary design is slightly higher than the safety limit.The simulation results show that the increase of bongrace type uniform pressure band can make the grounding grid security meet the requirements.(3)The grounding module is equivalent to a columnar metal conductor by using the COMSOL software,so that the simulation of the grounding module in the CDEGS software is feasible.The high short-circuit current of intelligent substation makes the cost of reducing resistance in the later stage of grounding grid greatly increased.In view of the problem that the grounding network has no significant effect on the later stage,the square and plum shaped grounding mod ules are researched by the use of CDEGS software.The results show that the plum shaped grounding module used as a vertical grounding body has a good effect in Intelligent substation grounding network.(4)An optimal design scheme for grounding grid of 110-A2-X1 and 220-A2-X1 in intelligent substation is proposed.The optimal design scheme of 110-A2-X1 and 220-A2-X1 grounding grids is using plum blossom grounding module to reduce resistance.In the study,it is found that the grounding network of 110-A2-X1 is more difficult to reduce the resistance than 220-A2-X1.The simulation verification of the CDEGS software docking network optimization scheme shows that the plum blossom grounding module can make the grounding grid meet the safety requirements,and ensure the safety performance of the intelligent substation grounding grid. |
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