通过在交直流混合微电网(hybrid micro-grid, HMG)与配电网间增加串联环节，实现交直流HMG并网运行时，配电网出现故障时较强的电能质量和穿越能力。在配电网故障的开始阶段，串联环节中的串联补偿变压器(the series compensation transformer，SCT)极易产生直流偏磁现象，影响电能质量。一般通过将SCT铁芯设计为两倍额定值的方法来解决这一问题，但这会使得SCT的体积和成本均大幅提高。为保证串联环节在交直流HMG与配电网间可靠、稳定、安全运行，减少SCT的体积和成本，对SCT直流偏磁的抑制十分必要。在分析SCT直流偏磁产生原理的基础上，提出一种通过控制串联环节输出电压首半周期幅值的直流偏磁抑制策略。在Simplorer、Matlab、Maxwell中进行联合仿真，结合实验结果表明，SCT直流偏磁得到有效抑制，验证了所提抑制策略的可行性和有效性。
英文摘要:
By adding a series link between the AC/DC hybrid micro-grid (HMG) and the distribution network, when the AC/DC HMG is connected to the grid, the power quality and traversing ability of the distribution network in the event of a fault can be achieved. At the beginning of a fault in the distribution network, the series compensation transformer (SCT) in the series link is prone to produce a DC bias phenomenon and affect power quality. This problem is usually solved by designing the SCT core at twice the rated value, but this will greatly increase the size and cost of the SCT. In order to ensure the reliable, stable and safe operation of the series link between the AC/DC HMG and the distribution network, and to reduce the size and cost of the SCT, it is necessary to suppress the DC bias of the SCT. Based on the analysis of the principle of SCT DC bias, a DC bias suppression strategy is proposed by controlling the amplitude of the first half cycle of the output voltage of the series link. Joint simulations were performed in Simplorer, Matlab, and Maxwell. Combined with the experimental results, the SCT DC bias was effectively suppressed, which verified the feasibility and effectiveness of the proposed suppression strategy.