Negative-Sequence Current Capability in Low-Capacitance Cascaded H-Bridge Static Compensators With Optimal Third-Harmonic Circulating Current Injection

Ezequiel Rodriguez, Ramon Leyva, Glen G. Farivar, Christopher D. Townsend, Josep Pou

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

The cascaded H-bridge (CHB) low-capacitance static compensator (LC-StatCom) has a limited negative-sequence current injection capability compared to a conventional CHB StatCom, due to the comparatively larger oscillations on the capacitor voltages. Placing limits on the ability to provide negative-sequence current to the grid for a given capacitor size is required to prevent overmodulation. This paper shows that these limits can be maximised by injecting an optimal third-harmonic circulating current. The effects of injecting the third-harmonic current on the capacitor voltages, both in balanced and unbalanced grid voltage conditions, are analyzed. Specifically, the procedure allows the knowledge of the potential capability of the LC-StatCom when injecting negative-sequence currents. The procedure is based on a linear programming approach. Although the procedure is applicable to any CHB StatCom, regardless of the submodule capacitor size, it is particularly important in LC-StatComs. To corroborate the proposed analysis, simulation and experimental results under balanced and unbalanced grid voltage conditions are presented.

Original languageEnglish
Pages (from-to)4544-4558
Number of pages15
JournalIEEE Transactions on Power Electronics
Volume38
Issue number4
Early online date2022
DOIs
Publication statusPublished - 1 Apr 2023

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