Research On Time Synchronization Method Of Distribution Internet Of Things Terminal Equipment

The low-voltage distribution network is prone to electrical fires due to leakage and arcing faults,which endanger personal safety and cause huge economic losses.In addition,a large number of distributed generations are accessed in the low-voltage distribution network,which requires further enhancement of monitoring capabilities.Using IoT technology to build distribution network and IoT deep integration of distribution IoT is the current solution to monitor low-voltage lines and realize new methods of fault detection.Low-voltage distribution monitoring terminal,as the key equipment for information collection and processing,the collected electrical quantity is the basis for accurate feedback of real-time operation status of distribution IoT.When abnormal data is collected,the master station can quickly react and excise the fault in time to guarantee the safety of users’ electricity consumption.In order to tag the collected data with time tags,the low-voltage monitoring terminal needs to have time synchronization function.And the cost and accuracy of existing timing methods cannot meet the requirements of low-voltage distribution network monitoring system.In order to solve the timing problem of the equipment at the distribution IoT terminal,the research work done in this thesis is as follows:(1)Various time synchronization methods and their limitations are analyzed,and the demand and performance requirements of time synchronization of LV distribution monitoring terminals for multi-point information-based fault detection and effective monitoring in the distribution network of things are summarized.(2)By analyzing and calculating the phase angle change of the voltage at the first end and the end of the low-voltage distribution line,it can be seen that the phase angle change of the voltage at both ends of the line is small,and the over-zero point of the voltage of the same perimeter wave can be used as the calibration signal for timing.Based on this principle,a time synchronization method combining voltage detection and timing command communication is proposed.Timing of low-voltage monitoring terminal equipment at the time when the industrial frequency voltage passes the zero point,using WiFi communication to transmit timing control commands.(3)The error sources in the time synchronization process of this thesis are analyzed,and the methods to reduce the errors in the timing process are proposed.Compared with other timing methods,the method in this paper does not need to add other equipment,has good economy,and can better meet the demand of timing of distribution network of things.(4)By building the actual experimental system,the test of LV distribution line timing method is carried out,including AC sampling,transmission delay and timing test.The test results show that the accuracy of the method in this paper can be better than 1ms,which verifies the feasibility of the timing method.There are many communication methods in LV distribution IoT,and the method in this thesis is based on WiFi communication method,but the timing method combining voltage detection and timing command communication can also be further extended to other communication methods to meet the communication timing requirements of LV distribution IoT.