Work

Active Power Backflow Suppression Strategy for Hybrid Cascaded H-Bridge PV Grid-Connected Inverters Under Inter-Phase Short-Circuit Faults

Year: 2026

Type: article

Abstract: For three-phase cascaded H-bridge (CHB) photovoltaic (PV) inverters, although existing methods can effectively suppress active power backflow under single-phase and two-phase short-circuit faults, they fail to do so over a wide operating range under interphase short-circuit conditions. As a result, the abnormal rise in DC-side voltage caused by active power backflow cannot be effectively suppressed across all operating conditions, posing a serious threat to equipment safety and system stability. To address this issue, this article takes the hybrid CHB PV inverter as the research subject and proposes a systematic solution that combines topological characteristics with control strategies. First, a classified autonomous control strategy based on coordinated negative-sequence voltage allocation (CNSVA) is introduced, which prioritizes directing the negative-sequence voltage to the three-phase bridge inverter with a common DC bus and incorporates zero-sequence voltage compensation to mitigate its impact on the CHB inverter. Second, to address the overmodulation problem that tends to occur under deep grid voltage sags, a composite control strategy integrating CNSVA and multiple harmonic injection is proposed. By injecting harmonics, the linear modulation range is extended, and the feasible region for positive- and negative-sequence voltage distribution coefficients is determined, ensuring stable system operation across all working conditions. Finally, a low-voltage, low-power experimental prototype is built to verify that the proposed control strategy can effectively suppress active power backflow and significantly enhance the transient stability and grid-connected continuous operation capability of the system.

Source: IEEE Transactions on Power Electronics

DOI: 10.1109/tpel.2026.3707735

Authors: Tao Zhao, Guangsheng Li, Zhijian Feng, Zixiang Sun, Xing Zhang, Xiaoqin Zheng

Institutions: Qingdao University, Hefei University of Technology

Language: English

Topic: Multilevel Inverters and Converters

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Affordable and clean energy, Industry, innovation and infrastructure

Open Access status: hybrid

Estimated APC paid: $2,645