The Realization Of Telemetry And Telesignalling Function Of Contactless On-load Voltage Regulating Distribution Transformer

The application of on-load voltage regulation technology has become the most direct and effective way to solve the voltage fluctuation of power network.With the development of distribution network automation,the research emphasis about on-load voltage regulation technology has gradually turned to contactless on-load voltage automatic regulating transformer,experts and scholars at home and abroad have made breakthrough based on a large number of theoretical research and practical exploration,in the early stage of this project,our research group also have been made remarkable achievements,which developed a prototype of on-load voltage regulation with protective function.According to the characteristic of the change of load will cause voltage change between primary side taps,we acquire voltage between primary side taps to know the load voltage status,however,the measured voltage is equivalent to the secondary side terminal voltage of transformer,can not fully reflect the actual status of load,it will lead to a certain amount of error between measured value and actual value;what’s more,when the on-load tap changer is broken down or has other faults,the protection mechanism of the prototype will run,that the air switch is tripped,the load regulation function is exited,and the transformer is automatically restored to the rated position so as to realize uninterrupted power supply,but this abnormal operation of transformer is difficult to be found by the operators,it will leave a hidden danger.In order to respond to the load voltage more accurately and truly,improve the voltage regulating performance,and eliminate the hidden danger after the on-load tap changer fault,this paper has designed an on-line monitoring device to realize telemetry and remote signal functions,which is based on the existing prototypes of contactless on-load voltage regulation with protective function.The device consists of a monitoring unit for voltage,which includes the voltage data acquisition and transmission part of the load point,and the voltage data receiving part at the contactless tap changer,a monitoring unit for tap changer fault,and a unit for voltage regulating control.Each unit takes the MCU as the control circuit core,during the normal running of the distribution transformer,the voltage detection circuit acquires load monitoring point voltage,then comparing the acquired voltage data with the range of voltage in program which set before,if the acquired voltage data is out of range,SIM800 wireless communication module will transmit the out of range voltage data to the microprocessor in voltage data receiving part through the GPRS network,this realizes the telemetry function of contactless on-load voltage regulating distribution transformer;when the tap changer is broken down,the air switch in the on-load voltage regulating transformer is tripped rapidly,then the MCU at the contactless on-load tap changer detects the fault signal,and transmits the fault alarm information to the operator on duty through the wireless communication module,so that the fault can be maintained and repaired in time,this realizes the remote signal function of contactless on-load voltage regulating distribution transformer.In the laboratory,using a three-phase adjustable voltage regulator with overcurrent and overvoltage protection function and a distribution transformer which is 30kVA 10/0.4kV consists of a 0～11kV three-phase high voltage regulator platform,providing power for the project prototype.The results of laboratory simulation test show that the contactless on-load voltage regulating transformer which using GPRS communication module detects the voltage at the load can transfer voltage data and complete the voltage regulation function;moreover,when the tap changer breaks down and the transformer runs under abnormal condition,the fault information can be sent to the operator on duty in a timely manner through the communication module.The application of wireless communication module of the contactless on-load voltage regulating distribution transformer can improve the automation level of distribution network in a large extent,promote the distribution network automation process,and can provide more high quality power for power user in the network terminal.