Study On Thermal Fault Monitoring And Early Warning Strategy Of Box Type Substation

Box type substation has many advantages such as small footprint,easy movement,short construction period,etc al,which is generally used in the residential areas and urban public places.However,many kinds of faults appeared during its operation process,which thermal faults account for biggest.Thermal faults seriously threaten the safe operation of the power system.Due to the interference and other reasons,the field monitoring data can not reflect the real-time state of the equipment.Besides,thermal faults prediction are only based on threshold,does not consider the relationship between the space,time and operating parameters.Therefore,a new thermal fault monitoring and early warning scheme is presented in this paper.Firstly,this paper outlines the research background and significance of the box type substation thermal fault;then it particularly introduces the digital signal processing knowledge interfacing such as FIR and data fitting;and communication means containing RS485,Ethernet;and communication protocol including Modbus,IEC104,and the thermal failure early warning strategy,which lays a foundation for the study of thermal fault monitoring technology and early warning strategy.Secondly,this paper introduces the overall design scheme of thermal fault monitoring,which can be divided into power monitoring part,temperature monitoring,communication and human-computer interaction.The temperature monitoring part adopts STM32F0 and radio frequency chip NRF24L01 as the embedded hardware platform It achieves the temperature measurement of isolating switch,transformer,power cable and busbar.The others uses of dual core structure of STM32F4+STM32F1,which has high data capacity.As the main CPU,STM32F4 mainly completes the current,voltage signal acquisition and communication with the temperature measurement module.As slave CPU,STM32F1 embedded u COS-II operating system mainly completes the communication between the monitoring device and the monitoring center and the communication between monitoring devices with the help of Modbus,IEC104 protocol.Then,this paper introduces the concrete implementation scheme of thermal fault warning.It adopts the improved combined weight similarity day to complete long-term failure prediction,and uses entropy weight method and order relation analysis method to calculate similar day and weight distribution,which effectively improves the prediction accuracy.For real time fault prediction,it based on equivalent resistance model and short term load forecasting,and uses probability density data filtering algorithm and spatial correlation analysis method to deal with the singularity data processing and feature extraction,which makes the fault signal analysis more accurate.Finally,it accomplishes the function experiment including communication experiment,instantaneous thermal fault experiment,long-term thermal fault experiment and short-term load warning experiment.The experimental results show that this paper not only can monitor the operation state of the box type substation,but also can predict the development trend in the early stage of the fault.