Development Of On Line Monitoring System For Medium Voltage Electrical Equipment Based On Wireless Power Energy Transmission Multiplexing Technology

The stable operation of smart grid is inseparable from the condition based maintenance of electrical equipment.The on-line monitoring of electrical equipment is the basis for condition based maintenance.The on-line monitoring of electrical equipment through sensor networks has the problem of high voltage side sensor's power collection.In order to meet the insulation requirements,the existing way is to supply power to sensor network by radio energy transmission,and the device status information monitored by sensors is transmitted through wireless communication module(ZigBee,etc.).Although this method solves the problem of sensor power supply and data transmission,the high frequency signal emitted by the wireless communication module will affect the protection and control part of the medium voltage electrical equipment,and the wireless communication module is the main loss of the monitoring terminal.In this paper,the radio transmission multiplexing technology is applied to online monitoring system to achieve the synchronous reverse transmission of radio and signal.It provides a new way for wireless sensor data transmission,and has important application value for medium voltage electrical equipment online monitoring system.First of all,a radio transmission multiplexing technology based on load modulation technology is proposed to transmit the state data of the electrical equipment on the high voltage side to the low voltage side,and then transmit the data received by the low-voltage side to the monitoring center through the power line carrier technology.Then,the modeling and analysis of the magnetic coupled resonant radio transmission system is carried out.Aiming at the maximum output power and transmission efficiency of the system,it is often impossible to have both.The maximum efficiency product is used as the objective function of the transmission coil of the optimization system.In addition,an equivalent model of E class HF power amplifier and magnetic coupling structure is established,and the effect of different.load modulation on the circuit performance is theoretically analyzed and verified by simulation.The influence of the surrounding metal on the system is also analyzed.Secondly,in order to give better consideration to output power and transmission efficiency,the maximum efficiency product is taken as the objective function,and the PCB coil is optimized under limited size space.According to the requirements of the switch cabinet's internal structure,high and low voltage insulation distance,sensor power consumption,data transmission rate and other requirements,the key indicators of the prototype were established.Combined with theoretical analysis and simulation results,the hardware circuit parameters of the system were designed.Finally,based on the above design method,we made an experimental prototype,verified the relevant theory,and tested the prototype system.The test results show that the online monitoring system is stable and reliable.The on-line monitoring system of medium voltage electrical equipment based on radio transmission and multiplexing technology has good application value.