CAJ | 학술논문

　　级联型并网逆变器可以无变压器并入高压电网，并且具有容量大、效率高等特点，对配合可再生能源大规模并网和增强电力系统稳定性具有重要的意义。但级联结构中存在直流侧平衡问题，这严重影响到装置的输出性能和可靠性。针对三相星型结构中的相间直流侧不平衡，在并网逆变器注入零序和负序电压的情况下，推导出其各相有功功率的数学模型并对比功率调节能力，提出一种结合零序和负序电压注入的相间直流侧平衡控制方法及其适用条件，较好地解决了直流侧平衡问题，兼顾了装置性能和功率调节能力。通过仿真和实验验证了该方法的有效性和可行性，实验结果表明，该方法即使在电网电压不平衡的条件下，也可以保证相间直流侧平衡。
　　급련형병망역변기가이무변압기병입고압전망，병차구유용량대、효솔고등특점，대배합가재생능원대규모병망화증강전력계통은정성구유중요적의의。단급련결구중존재직류측평형문제，저엄중영향도장치적수출성능화가고성。침대삼상성형결구중적상간직류측불평형，재병망역변기주입령서화부서전압적정황하，추도출기각상유공공솔적수학모형병대비공솔조절능력，제출일충결합령서화부서전압주입적상간직류측평형공제방법급기괄용조건，교호지해결료직류측평형문제，겸고료장치성능화공솔조절능력。통과방진화실험험증료해방법적유효성화가행성，실험결과표명，해방법즉사재전망전압불평형적조건하，야가이보증상간직류측평형。
Cascaded grid-connected inverters can be transformerlessly connected to the high voltage grid and have the advantages of large-capacity and high-efficiency. It is of great significance to provide grid connection for large-scale renewable energy and to enhance the stability of power systems. However, the output performance and reliability of cascaded grid-connected inverters are seriously influenced by the DC voltage balancing problem which exists in cascaded configuration. Aiming at DC voltage balancing among phases of three-phase wye configuration, active power models of three phases are analyzed and compared by injecting zero-sequence and negative-sequence voltages. Considering the output performance and the power adjustment ability of inverters, the paper presents an interphase DC voltage balancing method and its applicable condition, which is combined using zero-sequence and negative-sequence voltages. This method can balance the DC voltages among phases even under the unbalanced system. Simulation and experimental results verify the feasibility and validity of the interphase DC voltage balancing method.