Leakage Monitoring System Of Distributed Photovoltaic Power Station Based On NB-IoT

In photovoltaic power stations,from photovoltaic arrays to grid-connected,the interconnection between devices is complex,which is easy to cause line leakage fault.Distributed power stations are widely distributed and difficult to unified management.In view of the fact that the sensor accuracy of photovoltaic power stations is low and the communication mode is not flexible,we design a leakage monitoring system based on Narrow Band Internet of Things(NB-IoT)communication.Firstly,according to the research status of leakage monitoring system of photovoltaic power stationat home and abroad,the key technical problems of leakage monitoring which need to be solved urgently are elaborated.According to the design principles and specifications of photovoltaic power stations,the overall design scheme of leakage current monitoring system is proposed.Secondly,the perception layer,transmission layer and platform application layer of leakage monitoring system are studied in depth.In the perception layer,in order to improve the accuracy of the sensor,the following work has been done.Firstly,ANSYS is used to model and simulate the magnetic modulation sensor,and the influencing factors of the sensor sensitivity are obtained.Secondly,the physical formula of the magnetic induction electromotive force is deduced under different conditions,and the optimization scheme of the magnetic core is obtained.Thirdly,through the Multisim software simulation,the signal conditioning circuit of the sensor is studied and improved,and the scheme of the sensor with two magnetic cores and half-wave excitation is obtained.In the laboratory,the sensor of this scheme is tested comparatively,and the results show that the sensor with two magnetic cores and half-wave excitation has better performance.In the transport layer,the debugging process of NB-IoT device communication is studied.The resource docking scheme between NB-IoT device module and Internet of Things cloud platform is discussed.The NB-IoT driver of STM32 MCU and the whole software design are completed.The data communication of leakage detection system based on NB-IoT is realized.In the application layer of the platform,based on the OneNET cloud platform of China Mobile Internet of Things,an application platform for leakage monitoring of photovoltaic power stations is designed and built,which realizes the visualization display of leakage current and GPS map location information and other equipment data streams.Finally,based on the photovoltaic power stationof the experimental building of North China Electric Power University,we test the leakage monitoring system.The experimental results show that the monitoring system can real-time monitor the leakage of each solar panel in photovoltaic power station,solve the key problems of leakage monitoring,and ensure the safe and reliable operation of photovoltaic power station.