摘要
固态变压器可以有效解决传统电力变压器在电力系统中的不足,其中级联型SST可以很好地适应高压电网。但级联结构中存在直流侧平衡问题,这严重影响到装置的可靠性。本文首先分析了单相SST的电路拓扑和工作原理,建立数学模型,进一步对现有的直流电压平衡控制方法进行了比较研究,并确定适合SST的平衡控制方法。通过实验验证了该方法在SST中的有效性和可行性,实验结果表明,该方法在复杂工况下也能够保障装置可靠运行并维持直流电压平衡。
The disadvantages in power system with traditional industrial frequency transformer can be resolved by SST(solid state transformer).Cascaded SST can be transformerless connected to the high voltage grid.However,the output performance and reliability of cascaded grid-connected inverter are seriously influenced by DC voltage balancing problem which exists in cascaded configuration.Firstly,circuit topology,operating principle and mathematical model of single-phase cascaded SST are analyzed.Then,active power adjusting ability of DC voltage balancing methods are compared.Finally,suitable DC voltage balancing method is confirmed.This method can balance the DC voltages even under complex condition.Experimental results verify the feasibility and validity of this method.
引文
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