Electric Power ›› 2022, Vol. 55 ›› Issue (7): 49-58.DOI: 10.11930/j.issn.1004-9649.202011082

• Power System • Previous Articles     Next Articles

Error Analysis and Correction of Voltage Sag Measurement for Capacitor Voltage Transformer

ZHOU Wen1, LIANG Jifeng1, JIAO Yadong3, LI Tiecheng1, LU Yanqiao2, LIU Yong4   

  1. 1. State Grid Hebei Electric Power Research Institute, Shijiazhuang 050021, China;
    2. State Grid Hebei Electric Power Co., Ltd., Shijiazhuang 050023, China;
    3. Anhui WuYi Electrical Technology Co., Ltd., Hefei 230031, China;
    4. State Grid Hengshui Electric Power Supply Company, Hengshui 053099, China
  • Received:2020-11-19 Revised:2022-02-19 Online:2022-07-28 Published:2022-07-20
  • Supported by:
    This work is supported by the Science and Technology Project of SGCC (Research on Key Technologies of Transfer Characteristics and Broadband Accurate Measurement of CVT In Non-power Frequency Conditions, No.5200-201924064A-0-0-00).

Abstract: Voltage sag is one of the most prominent power quality problems in modern power grid. When monitoring voltage sag in a large range of high-voltage systems, the adverse effects caused by capacitor voltage transformer (CVT) with energy storage elements must be considered. According to the structure of the CVT, the error of voltage sag measurement is deduced, and the internal and external factors influencing the error are identified. Then, a simulation model is built, and a study is made in detail on the influences and sensitivities of the initial phase angle of sag, residual voltage, CVT parameters and load on voltage sag duration, sag amplitude and phase jump. Finally, a virtual impedance compensation based method is proposed for CVT’s voltage sag measurement error correction, which eliminates the problem of measurement error diversity caused by voltage sag uncertainty. The simulation results show that the method is effective and provides a feasible correction scheme for the accurate measurement of voltage sag in the high-voltage system which widely adopts CVT.

Key words: capacitor voltage transformer, voltage sag, error, correction