Design And Realization Of Controller For On-load Capacity And Voltage Regulating Transformer

In the process of power transmission,the loss of distribution transformer is very large.Due to the wide geographical area and the frequent fluctuation of the power load affected by the seasonal period,the rural distribution network cannot operate at high efficiency for a long time and the transformer is not fully utilized.Although the "bus-sub transformer" can be installed to solve the problem,it is not reasonable from the economic point of view.This problem can be effectively solved by installing on-load capacity and voltage regulating transformer.The safe and reliable operation of this special transformer is closely related to its controller.At present,there are few studies on on-load capacity and voltage regulating transformer driven by permanent magnet mechanism,so it is necessary to study and design a controller with good performance.The main research contents of this paper are as follows:(1)On the basis of studying the principle of on-load capacity and voltage regulating transformer,Simulink simulation model was established to realize the regulation of capacity and voltage.The principle of energy saving and loss reduction of on-load capacity regulating transformer is analyzed,and the capacity regulating point is calculated according to the load loss and no-load loss of on-load capacity regulating transformer.(2)The on-load tap changer studied in this paper is a tap changer driven by a permanent magnet mechanism with on-load capacity and voltage regulation.The principle and action characteristics of the double break vacuum arc extinguishing chamber and the permanent magnet operating mechanism in the switch are analyzed in detail.The basic equivalent circuit of permanent magnet mechanism and the basis of capacitance selection are introduced.(3)The controller design scheme is proposed to realize functions such as data acquisition,transformer state detection,on-load capacity and voltage regulation tap switch drive,automatic capacity and voltage regulation,manual capacity and voltage regulation,data storage and serial port communication.The ATT7022 E energy metering chip is adopted for data acquisition,and relay control circuit is adopted for on-load capacity and voltage regulating tap switch drive.(4)Under the Keil uVision platform,combined with the real-time operating system FreeRTOS,modular program framework was adopted to complete the software program design corresponding to the hardware.In the design process of capacity and voltage regulation,the current state of transformer,load value,capacity regulation point and voltage setting value should be determined together with appropriate delay,so as to ensure the accuracy of operation.(5)Build the experimental platform and conduct module debugging for the controller.The proper operation of on-load capacity and voltage regulating tap changer,signal acquisition,data storage are completed.The feasibility of the device is verified by the overall debugging.