应用于HVDC系统的高频模块化直流变压器匹配移相控制策略

高频模块化直流变压器(HMDCT)是构建直流电网的核心设备。HMDCT在传统移相(TPS)控制下的高频交流不匹配工作状态会带来较大的高频电流应力与回流功率,降低了HMDCT的传输效率,因此解决该技术瓶颈成为进一步促进HMDCT在直流电网中应用的关键。鉴于此,提出了一种基于桥臂子模块动态投切技术的HMDCT交流链匹配移相(MPS)控制策略。由分析及实验结果可知,当采用交流链MPS控制策略时,不论HMDCT两端的直流电压变比如何,HMDCT的交流链电压均能够保持在匹配工作状态;且在传输功率相同时,相比于TPS控制,交流链MPS控制具有更小的回流功率及更高的效率。通过样机实验对理论分析的正确性与有效性进行了验证。

Matching phase-shift control strategy of high-frequency modular DC transformer for HVDC system

HMDCT(High-frequency Modular DC Transformer) is the core equipment of constructing DC power grid. When HMDCT is under the TPS(Traditional Phase-Shift) control, the mismatching working state of its high-frequency AC link will cause high-frequency current stress and backflow power, which decreases the transmission efficiency of HMDCT. Therefore, the key to further promote the application of HMDCT in DC power grid is to solve this technical bottleneck. In view of this, an AC link MPS(Matching Phase-Shift) control strategy of HMDCT based on the dynamic switching technology of bridge arm sub-modules is proposed. The analysis and experimental results show that, when HMDCT is under the AC link MPS control, the AC link voltage of HMDCT can be maintained in the matching working state regardless of the DC voltage ratio at both ends of HMDCT. When the transmission power is the same, compared with the TPS control, the AC link MPS control has smaller backflow power and higher efficiency. The correctness and validity of the theoretical analysis are verified by the prototype experiment.