| With the promotion and deepening of distribution automation construction,distribution terminal is more and more widely used and its role has become more prominent.The terminal of the distribution automation system is arranged at the on-site distribution equipment,which is responsible for collecting real-time data of the operation conditions of the distribution network and distribution equipment,uploading fault information to the main station of the distribution automation system,and receiving commands from the main station to adjust and control the distribution equipment.Power distribution terminal power system usually adopts a power supply mode that combines AC power supply and valve regulated lead acid battery backup power supply.When the distribution line power failure or malfunction due to the loss of AC power,it needs backup battery terminal units,communications equipment and power distribution switches to provide a certain time(usually requires more than 4 hours)of the power supply ability.If the backup battery of the power distribution terminal is unavailable,the power distribution switch cannot work accurately,which increases the fault scope and reduces power supply reliability.Therefore,the availability detection of the backup battery of the distribution terminal is important to ensure the normal operation of the distribution automation function.Firstly,this thesis introduces the internal structure and working environment of the backup battery of the distribution terminal,analyzes the failure causes of the backup battery of the distribution terminal under different working conditions,and selects the optimal battery equivalent circuit model that can characterize the state.The simulation verification uses the physical environment simulation software COMSOL.Secondly,aiming at the problem of high misjudgment rate in the availability detection of backup batteries in distribution terminals under long-term outage condition,a rapid detection scheme for battery availability based on short-term charging is determined by analyzing the equivalent circuit model under this operating condition.The distortion characteristics of the terminal voltage data curve of the battery pack are used as the basis for the extraction of battery fault features.And the modulus maxima of the wavelet transform on various scales are used to characterize the failure battery the abrupt change point of the fault component,is used to detect the mutation quantity,to determine whether they contain faults in the battery.This method improves the shortcomings of the previous detection method and realizes the rapid detection and determination of the availability of the backup battery of the power distribution terminal that has been out of service for a long time.Finally,aiming at the problems of poor reliability and low accuracy in the availability detection of the backup battery of the power distribution terminal running online,through the analysis of the failure cause of the backup battery under this working condition,various electrical parameters affecting the performance of the battery are determined.And the monitoring system is set up for the availability of backup battery in the distribution terminal,which designed the electrical parameters detection circuit of related batteries,and carries out real-time detection and monitoring of each electrical parameter of the battery bank.At the same time,the improved DBSCAN algorithm is introduced to update the effective field radius in real time by using the safety threshold of each electrical parameter of the battery and the historical working conditions of the battery,so as to screen out the abnormal data of the battery at the threshold boundary in time,and effectively distinguish the availability of a large number of backup battery packs in the distribution network,and the availability of backup battery packs in online distribution terminals can be quickly determined.Under different working conditions,according to the working characteristics of distribution terminal backup battery,the rapid detection method of the battery availability under the condition is determined to guide the staff in the failure of the battery replacement treatment,which improves the work efficiency and reduces the waste of resources caused by misjudgment,has the good practical significance in engineering practice. |
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