The Calculation Of Power Frequency Electric Field With Charge Simulation Method Based On Domain Decomposition Method

Charge simulation method is widely used for its simple principle,unknown amount and fast solution speed.However,the calculation is sometimes limited by the hardware condition of the computer and cannot be carried out smoothly when the model is complex or the computation scale is large.In this case,the whole region should be divided into several sub regions,and the calculation is carried out separately in each sub region so that the whole calculation can be carried out smoothly.Charge simulation method combined with overlapping domain decomposition method is proposed.This method can provide an effective way to calculate the complex electric field and break the limit of the computer capability.It is significant for the design of transmission and transformation engineering and the evaluation of electromagnetic environment.The work of investigation and the paper are organized as follows:(1)The hybrid method is proposed based on the overlapping domain decomposition method and the charge simulation method.Based on the hybrid method,the whole region is divided into two sub regions and the accuracy and efficiency of the hybrid method in the scene of single circuit transmission lines and double circuit transmission lines are verified.Then the whole region is divided into three sub regions and the accuracy and efficiency of the hybrid method in the scene of three circuit transmission lines are verified.Compared with CSM,calculation results indicate that the method can save memory and reduce the computation time of field with high accuracy.(2)Based on the verification of the method,calculation efficiency with different relaxation factors and the size of overlapping area is briefly discussed in different scenes.The results show that the number of iterations is the least when the relaxation factor is appropriate.The relationship between computation amount and iteration times can be well balanced when the width of the overlap area is appropriate.The analysis of iterative influence factors can fully show the superiority of the iterative algorithm.(3)The power frequency electric field near the building with on trees around it and the field with trees around it are calculated and analyzed,respectively.The results show that planting trees around the building can effectively reduce the electric field.Then the power frequency electric field of 500 kV transformer area is calculated by the method.The accuracy of the method is further verified by comparing the calculation results with the actual measured data.The results show that the firewall has a great influence on the field around the transformer,and the radiator and the oil pillow have a great influence on the field of the whole area.(4)The transformer room model of 500 kV indoor substations is established and the field around the transformer is calculated when the import and export lines are in different way.The field is weaker when the import and export lines pierce through the wall horizontally than that when lines pierce through the wall vertically.The field is weaker when the import and export lines are in cable feeder way and in gas insulated feeder way.Bare conductors should be avoided to use in indoor substations so as to save space and reduce electromagnetic pollution.