Research On Measurement Method Of Grounding Impedance Based On Diffenent Frequency And Multi-point Synchronous Vector Acquisition

The public reference ground level established by large-scale power facilities using the ground network not only provides a common base point for power facilities,but also provides a rapid discharge path when lightning strikes,faults and other abnormal conditions occur,ensuring the safety of surface level distribution in the field area and providing important security for people and equipment.Keeping the grounding network in good condition before operation and during operation is an important guarantee for the safe and reliable operation of equipment.Therefore,the accurate and efficient measurement of grounding network characteristic parameters is the prerequisite for the correct evaluation of grounding network status,especially the monitoring and early warning of grounding network status under operating state is of great significance.First of all,through the detailed analysis of the principle,means of realization and effect evaluation of large-scale grounding network ground impedance measurement,which is widely used at present,the ground impedance measurement method combining multi-point synchronous phase acquisition with hetero-frequency method is proposed.This method uses GPS system to measure the time of current input and realizes the synchronous measurement of each current.The frame base,cable metal outer sheath and other shunt phasors are collected in situ and transmitted to the measuring end wirelessly,so as to realize synchronous and accurate collection of multi-point phasors.According to the phase Angle characteristics of the shunt phasor,the shunt and circulation are screened,and the accurate shunt coefficient of the ground network is obtained by phasor calculation.Secondly,based on the theoretical basis of the different frequency and multi-point synchronous phasor measurement method,the functional requirements of the different frequency and multi-point synchronous phasor measurement system are analyzed,the network architecture is designed and a practical different frequency and multi-point synchronous phasor measurement system is set up,and the testing process is put forward on the basis of engineering practice.Finally taking a 500 k V substation in Feng Cheng as the application object,the measurement system of this paper measures the grounding impedance of the ground network and compares it with the 0.618 method,and the results show that the error of the measurement results of this method is within the standard range,to prove the method adapted to run the substation ground network model under the complex interference environment parameter measurement,and access to accurate,efficient and reliable measuring data.Based on the practical application,this paper put forward based on the different frequency method and multi-point synchronous phasor acquisition of large ground network grounding impedance measurement method is easy to operate,good results are accurate,repeatability and measuring the advantages of low cost,which can realize the grounding impedance parameters such as accurate and efficient measurement,and then realize the prediction of the ground,assessment,it has universal application value.