Research And Design Of The Power Transformer DC Resistance Measuring Instrument

Power transformer is one of the most important power system transmission and distribution equipments, its normal operation exerts quite a great influence on stability and safe operation of the power grid. Winding DC resistance measurement, as one of the major programs of power transformer factory preventive test, is the most direct way to acquire a series of performance parameters of power transformers rapidly. As there exists problems of low accuracy, time consuming and complexity in the traditional measuring methods, this paper studies and design a new type of power transformer dc resistance measuring instrument.In this thesis, the research status of the power transformer DC resistance measuring instrument is introduced, and the commonly used existing measuring methods and summarizes the advantages and disadvantages of various methods are analyzed, then an improved measuring method based on the high voltage charging low voltage measuring is obtained. According to the new measuring method, with the MSP430LF149SCM as the core,the hardware and software designs of the measuring instrument have been completed. The hardware design consists of measuring power and detection and control circuit. The power supply combines the advantages of switching power supplies and linear power supplies. The output voltage is stabled by switching power supply, and then by a linear power supply. The output voltage of the linear power can automatically be adjusted according to the DC resistance of size. Dual-channel simultaneous are used to sample the voltage and current signals. Meanwhile, keyboard, LCD, printing, storage, and clock circuitry are included in the measuring instrument. Operation of measurement, data processing, preservation and printing are included in the software, which was programed by the state analysis method.Lastly, the simulation experiments and field experiments on the measurement power and the prototype are implemented, and makes a clear comparison of the difference between other power supply and new measuring instrument. The experimental data confirms that the measurement power has high accuracy and load adaptive capacity. The measuring instrument can finish measuring tasks quickly and accurately, execute smooth transition.