Research On On-Line Detection Technology Of Distribution Transformer Based On Loss Power Comparison

Distribution transformer,as one of the key equipment in distribution network,is expensive and has a high failure rate.Distribution transformers,as terminal equipment of the power grid,will not only cause direct economic losses due to equipment damage and indirect economic losses due to power supply interruption,but also adversely affect the safe and stable operation of the power system in case of an accident.Therefore,in order to correctly make scientific and accurate judgment on the actual operation of distribution transformers and predict the development trend of equipment,it is necessary to carry out online detection on the running state of distribution transformers.Active power and load loss are the main technical parameters for the operation of distribution transformers.The on-line measurement of these parameters can not only grasp the operation status of distribution transformers in time,but also find out the potential defects of the equipment.This thesis for distribution transformer active power rate and online measurement problem of load loss conducted in-depth research,based on the analysis of working principle and operation parameters on the basis of distribution transformer,the active power was deduced respectively rate,short circuit loss and winding temperature rise formula,on the basis of building the online measurement of the amount of the relevant state simulation model simulation test,the main work and innovation of this thesis lies in the following aspects:(1)The on-line detection method of distribution transformer state based on active power change rate was proposed.By analyzing the mathematical relationship between distribution transformer fault and electrical characteristic quantity,the method of signal acquisition,analysis and calculation of online detection system was studied,and the active power loss of distribution transformer in actual operation was obtained.Through real-time calculation of theoretical power loss of distribution transformer under different load conditions and comparison with actual active power loss,the online state detection of distribution transformer based on the change rate of active power was realized,and the effectiveness of the loss power detection method was verified through relevant fault simulation tests.(2)A winding fault identification method of distribution transformer based on on-line load loss detection was proposed.By constructing the equivalent circuit model and deducing the specific calculation formula of equivalent resistance,the on-line calculation and measurement method of distribution transformer load loss and winding temperature rise were studied,which provides a theoretical basis for the on-line detection system of distribution transformer loss and power.The on-line detection method proposed in this study does not need to add any secondary equipment.(3)The state detection and evaluation of distribution transformer based on power comparison was realized.Based on the on-line electrical parameters of current and voltage transformers,combined with the state evaluation system and method of relevant auxiliary information,a comprehensive model for on-line evaluation of operation state of distribution transformer windings was established.Membership function was introduced to solve the boundary transition problem between various state levels.The qualitative parameters were quantitatively analyzed by the scoring method,The real-time detection and parameter evaluation of distribution transformer were realized.