The On-line Calibration System Of High-voltage Current Transformer Based On Virtual Instrument

As one of foremost electric installation, accuracy and stability of the current transformer is the vital guarantee for power system metering, protection, monitoring. However, currently verifying the CT just confines to regular maintenance, monitoring the on-line operation current transformer became a new hot spot.This paper puts forward a design of the on-line calibration system based on virtual instrument technology, which realizes the on-line monitoring of the High-Voltage Current Transformer with comparison. Full-text elaborates the theory and design proposal of the system , and discusses the various components else. The text introduces the software platform from three aspects such as the serial communication based on LabVIEW , non-synchronous sampling error compensation as well as error calculation. Finally, it carries out the uncertainty analysis of the calibration system with field testing data.Virtual instrument as a platform to achieve fourth-order rectangular convolution window of FFT algorithm can effectively reduce the measuring error caused by asynchronous sampling. The on-line calibration system based on virtual instrument technology can avoid the noise caused by hardware, and decrease the source of the measuring error. The system has achieved a high accuracy of CT measurement , which enhances both the flexibility of digital signal processing and the computing speed as well. On the other hand, the software exploitation, debugging and improving are easier, compared with the hardware circuit. The realization with virtual instrument is flexible and with low fabrication costs and short empoldering period.At present,the on-line calibration system has been tested on 220KV line with good running status, which shows that the system has satisfied 0.1 level design requirement.