Application And Research Of Virtual Instruments Technology In The Power System Measuring

Currently, the separation of power generation and transmission from electric power industry which carries out the system reform makes the accuracy and fairness of the electric energy measurement highly concerned by all parties. The errors of the current transformers directly affect the error of the electric energy measurement. Therefore, the necessity of monitoring the errors of the current transformers is unsuspicious. In order to guarantee the accuracy of the electric energy measurement, we need to monitor the on-line operation current transformer without power cut.In the paper, a calibrating system with current transformers has come up by adopting Virtual Instruments technology and by reckoning proportion error and angle error by adopting software way. Which made the system can calibrate simulative and digital signal.In the paper, the elementary conception of Virtual Instruments was introduced firstly. Next, the hardware and software correlated to the system was introduced. The hardware includes the choice to transducer, the way of powering in the high voltage side and the modulated signal. The software includes the SCM process, the rock-bottom data disposed by VC++ and data analyzed by LabVIEW and so on. The SCM process can realize synchronous sample and optical fiber communication in the high voltage side, data receiving in two Channels, PC communication and analogues output in the low voltage side.In the paper, the simple Frequency-locking arithmetic and Quasi–Synchronous arithmetic was designed to dispose sampling data in the part of rock-bottom data process. The major idea of designing is to measure the frequency of analog signal accurately and prolong sampling data calculated by FFT. By experimentation validating, this arithmetic can compensate for non synchronous error effectively.The experiment shows in the system, the changes of the ratio error less than 0.05%,the changes of the angle error less than 0.03°in 50Hz; the changes of the error less than 0.02% when the frequency changes from 49.8Hz to 50.2Hz.The design realizes 0.1 lever accorded with the technical requirement of the system and finishes the target of the on-line calibrate to the current transformer.