【目的】针对有源配电网中,传统双向互联变换器开关容量要求高、维护成本大的问题,本文提出一种由三相有源变流器(TAC)和三相不可控整流器(TDR)组成的混合变流器。【方法】首先,设计了混合变流器的工作机制与控制架构:当直流侧出现功率缺口时,电能通过TDR流向直流侧,此时TAC作为有源滤波器工作;直流侧出现功率富余时,混合变流器则将能量传回交流电网。其次,针对其并联结构易引发环流且导致额外损耗的问题,深入分析了环流的产生机理及其影响因素,并提出一种基于多载波脉宽调制(PWM)的环流抑制策略。其中,有源零状态脉宽调制(AZSPWM)策略表现最优。【结果】试验表明,与传统正弦PWM相比,所提AZSPWM策略能有效降低混合变流器的环流。此外,该策略在整流滤波模式和能量再生模式下,网侧电流的总谐波失真均显著降低,且大幅降低了混合变流器系统的整体功率损耗。【结论】所提混合变流器拓扑具有良好的可行性,环流抑制策略能有效解决模块间环流问题,验证了本文AZSPWM策略的正确性与有效性。

[Objective] To address the issues of high switching capacity requirements and significant maintenance costs in traditional bidirectional interlinking converters within active distribution networks, this paper proposes a hybrid converter consisting of a three-phase active converter (TAC) and a three-phase diode rectifier (TDR). [Methods] Firstly, the operating mechanism and control architecture of the hybrid converter were designed: when a power deficit occurred on the DC side, electrical energy flowed through the TDR to the DC side, and the TAC operated as an active filter. Conversely, when there was a power surplus on the DC side, the hybrid converter could feed energy back to the AC grid. Secondly, to address the issue of circulating currents caused by the parallel structure, which led to additional losses, the generation mechanism and influencing factors of the circulating current were analyzed in depth. Accordingly, a circulating current suppression strategy based on multi-carrier pulse width modulation (PWM) was proposed. Among the evaluated strategies, the active zero-state pulse width modulation (AZSPWM) strategy demonstrated the best performance. [Results] Test results showed that, compared with the traditional sinusoidal PWM, the proposed AZSPWM strategy effectively reduced the circulating current. Besides, the total harmonic distortion of the grid-side current was significantly reduced under both rectifier-filter and energy-regeneration modes, and the overall power loss of the system was also cut down markedly. [Conclusion] The proposed hybrid converter topology demonstrates strong feasibility, and the circulating current suppression strategy effectively addresses the inter-module circulation issue, confirming the correctness and effectiveness of the proposed AZSPWM strategy.

湖北省自然科学基金(2024AFB584)；国家自然科学基金(52377191)