Research And Application Of Key Technologies For Condition Monitoring Of Power Capacitor Complete Sets

With the continuous development and progress of society,there are more and more inductive reactive power loads in the power system,and the system’s demand for reactive power is also increasing.There are many types of reactive power compensation devices available,but among the numerous reactive power compensation devices,power capacitor complete sets are widely used due to their advantages of simple manufacturing,low cost,and high operational reliability.Series reactors and power capacitors are the most important electrical equipment in the reactive power compensation loop of a complete set of power capacitors.However,in the actual operation process,certain faults often occur.If the faulty equipment is not found and handled in time,it will not only affect the utilization of power capacitor complete sets of equipment and threaten the safe operation of other power equipment in the power system.Therefore,it is particularly important to study the fault characteristics and failure mechanism of series reactors and power capacitors,explore the most sensitive parameters reflecting equipment failures,and realize real-time monitoring of the operating status of electrical equipment and send out corresponding signals.Since the existing monitoring methods of the power capacitor complete set of devices cannot effectively reflect the failure of the series reactor,this article focuses on the failure mechanism and physical characteristics of series reactors.This article first studies and analyzes the fault types and failure mechanisms of series reactors and power capacitors,and briefly analyzes the equivalent circuits of series reactors and power capacitors and their basic parameter calculations;Then use COMSOL finite element simulation software to establish a two-dimensional axisymmetric model of the series reactor,focusing on the study and analysis of the changes in electromagnetic parameters such as the magnetic field,short-circuit loop current,equivalent resistance,equivalent inductance,equivalent impedance,loss factor and power factor of the series reactor after the turn-to-turn short-circuit fault occurs;Finally,on the basis of the equivalent parameters calculated by COMSOL simulation,circuit simulation module Matlab/simulink is used to study and analyze the influence of the inter-turn short circuit fault of the series reactor on the reactive power compensation loop current,reactor voltage and active power consumed by the reactor.The research results show that the location of the short circuit fault point of the reactor is different,and the degree of change of each electromagnetic parameter is also different.On the whole,the severity of magnetic field distortion and the absolute value of the rate of change of electrical parameters show a trend of increasing from the end to the middle and from the inner layer to the outer layer.However,among the electrical parameters,the loss factor has the largest rate of change.It is the most sensitive to turn-to-turn short-circuit faults,so it can be used for on-line monitoring and protection of dry-type air-core series reactor turn-to-turn short-circuit faults.In view of the close relationship between the various parameters of the power capacitor complete set of devices,and the difference in the degree of reflection of different parameters to the fault,this article proposes a technical route for multi-parameter condition monitoring.And the article proposes an overall monitoring plan for the complete set of power capacitors.Through hardware design and software design,an online monitoring device for the complete set of power capacitors is finally developed.On the one hand,the device realizes real-time monitoring of the operating status of the power capacitor complete set of devices,and on the other hand,it can issue alarm signals to faulty equipment and issue trip instructions.It provides a strong guarantee for the safe operation of the complete set of power capacitor devices.