Journal of Power Electronics

The Korean Institute of Power Electronics (전력전자학회)
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Online broadband grid impedance estimation method based on multi-objective optimized random PWM

  • Yan Du (School of Electrical Engineering and Automation, Hefei University of Technology) ;
  • Shiyou Yang (School of Electrical Engineering and Automation, Hefei University of Technology) ;
  • Chunran Gao (School of Electrical Engineering and Automation, Hefei University of Technology) ;
  • Xiangzhen Yang (School of Electrical Engineering and Automation, Hefei University of Technology) ;
  • Houbo Wu (School of Electrical Engineering and Automation, Hefei University of Technology) ;
  • Jianhui Su (School of Electrical Engineering and Automation, Hefei University of Technology)
  • Received : 2022.12.27
  • Accepted : 2023.06.26
  • Published : 2023.12.20
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Abstract

Grid-connected inverter (GCI)-based online grid impedance estimation (GIE) can be used in the fields of grid state monitoring, fault diagnosis, and the stability control of grid-connected equipment, which can collectively improve the intelligence of GCI. However, the available frequency range of GCI-based GIE is limited by the bandwidth of the controller because a perturbation signal is injected into the reference current. To broaden the bandwidth of grid impedance estimation, an online GIE technology based on multi-objective optimized random pulse width modulation (MOO-RPWM) is proposed in this paper. Besides taking advantage of the harmonic dispersion characteristic of RPWM, the distribution of the switching frequency is further optimized by the constraints on the measurement accuracy and the total harmonic distortion (THD) of the grid current. Moreover, the frequency boundary is constrained by the frequency range of GIE, the stability of the system, and power loss. A genetic algorithm (GA) is applied to obtain the switching frequency sequence that satisfies the optimization targets. A single-phase grid-connected inverter system is built on a StarSim hardware-in-the-loop (HIL) platform to verify that MOO-RPWM-based GIE has the advantages of a broad GIE range, high accuracy, and low disturbance.

Keywords

Acknowledgement

This work was funded by National Key R&D Program of China under Grant 2021YFB2601403.

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