Electric Power ›› 2022, Vol. 55 ›› Issue (11): 73-83.DOI: 10.11930/j.issn.1004-9649.202111068

• Power System • Previous Articles     Next Articles

Wide-Band Harmonic Impedance Measurement Device for Wind Grid Based on Cascaded H-Bridge Converter

YU Yongjun1, XU Liguo2, LIN Zijie3, SUN Binghan4, LIU Qiujiang4, WU Zhensheng4, REN Zhijie5   

  1. 1. Electric Power Research Institute, State Grid Xinjiang Electric Power Co., Ltd., Urumqi, 830011, China;
    2. Sinohydro New Energy Development Co., Ltd., Beijing 100160, China;
    3. School of Economics and Management, Tsinghua University, Beijing 100084, China;
    4. School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044, China;
    5. HiWing General Aviation Equipment Co., Ltd., Beijing 100074, China
  • Received:2021-11-15 Revised:2022-03-14 Published:2022-11-29
  • Supported by:
    This work is supported by Science and Technology Project of SGCC (No. SGXJDK00DWJS2100059) and National Key Research & Development Program of China (Internet of Things and Smart City Key Technology and Demonstration, No.2018YFB2100100).

Abstract: In wind power generation, the coupling of the wind farm power pooling system with the grid may cause high frequency resonance problems and affect the power quality of the grid. It is therefore important to study the grid impedance frequency characteristics in depth. A wide-band harmonic impedance measurement device is proposed for wind grid based on the active intervention method, which injects a certain disturbance current into the common connection point. This solution uses a three-phase cascaded H-bridge converter as the harmonic generation and a stratified control strategy for the control part. The harmonic currents of different frequencies are injected into the 35 kV bus of the wind farm in the range of 100~5000 Hz, and the input impedance of the 35 kV port of the wind farm is obtained by measuring the voltage and current at the injection point. The proposed measurement device does not require rectification and is able to emit positive and negative sequence harmonic currents with controllable amplitude and frequency. The device can obtain accurate positive sequence and negative sequence harmonic impedance with the advantages of small size, simple structure and reliable control strategy. Finally, detailed Matlab simulations have verified the effectiveness of the system topology and control strategy.

Key words: cascaded H-bridge, wind grid, harmonic impedance testing, power quality, stratified control strategy