不平衡负荷下PET输出级电能质量优化控制

近年来,伴随新型电力系统在电源侧大规模新能源并网及其渗透率的不断提高,用户侧负荷更加复杂多元化、非线性化,致使配电网电能质量下降。本文针对不平衡负荷情况下配电网输出电压不平衡、低压直流电压脉动及谐波注入等问题,基于T型三电平输出级的电力电子变压器三级拓扑结构,采用SVPWM调制和中点电位平衡技术,设计了一种计及正/负双序电流的优化控制策略,保障三相电压平衡或直流电压恒定,实现配电网稳定运行。仿真分析和验证结果表明,该方法有效可行,能够有效改善不平衡负荷条件下配电网电能质量。

Output Stage Optimal Control of Power Electronic Transformerunder Unbalanced Load

In recent years, with the increasing penetration rate for gird integration of new energy generation, the loads are more diversified and nonlinear on the user side, resluting in the decline of power quality. Aiming at the problems of unbalanced output voltage, low-voltage DC voltage oscillation, and harmonic injection of distribution network under unbalanced load, based on the tertiary topology of power electronic transformer with T-type three-level output stage using SVPWM modulation and neutral point potential balance technology.It can ensure three-phase voltage balance or constant DC voltage and realize stable operation of distribution network. Simulation analysis and verification results show that this method is feasible and effective, and can effectively improve the power quality of distribution networks under unbalanced load.