Research On Online Monitoring System Of Bushing Insulation Based On Reference Phase Method

With the development of national power,people’s demand for electricity is increasing,and the voltage level and capacity of power systems are gradually increasing.One of the important components of transformer is bushing,its safe and reliable operation is related to the operation of transformer and even the whole power system,different from the traditional power outage preventive test,which can ensure real-time monitoring and predict the fault trend,online monitoring of transformer bushing insulation has become an important direction for the development of modern online monitoring technology.As one of the transformer bushing insulation parameters,the reliable measurement of the dielectric loss factor tanδ in real time is the most important part to realize the online monitoring of transformer bushing.By analyzing the capacitive bushing structure and dielectric loss concept,studying the online monitoring principle and method,analyzing and studying the harmonic analysis method of dielectric loss algorithm,analyzing the main environmental interference factors to which the online monitoring system is subjected during operation and proposing corresponding measures to reduce the influence of interference on signal acquisition and transmission and data acquisition.In this thesis,the overall structure of the transformer bushing insulation online monitoring system is designed,Online monitoring principle of "reference phase method" based on absolute method,Performing the design of hardware and software parts.The hardware design idea is based on the DSP unit controlling the local monitoring unit to realize the acquisition and processing of the end shied leakage current and PT reference voltage signal,and the data transmission through CAN2.0 communication bus.The software is modularized,Subdividing the lower part into several independent subroutines such as data sampling,data processing,communication interrupt,etc.,while The upper computer realizes the functions of data analysis and diagnosis,management and early warning.After the design and production,the installation and commissioning are carried out in the intelligent substation.The feasibility of the system is studied by analyzing the measurement data of the field application of the system through the method of vertical and horizontal comparison,and the results prove that the system can accurately and reliably monitor the dielectric loss factor tanδ in real time,which can bring considerable economic benefits.