Low voltage ride-through of single-phase transformerless photovoltaic inverters
Low voltage ride-through of single-phase transformerless photovoltaic inverters
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DOI：
10.1109/ecce.2013.6647340
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发表时间：
2013-10
期刊：
影响因子：
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通讯作者：
Yongheng Yang;F. Blaabjerg;Huai Wang
中科院分区：
文献类型：
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作者：
Yongheng Yang;F. Blaabjerg;Huai Wang
随着光伏系统普及率的不断提高，无变压器光伏逆变器将得到更广泛的应用，以实现高效率。然而，在高度光伏集成的配电系统中可能会出现问题。例如，由于防孤岛保护，所有光伏系统突然停止可能引发电网干扰。因此，一些国家正在修订具有下一代光伏系统辅助服务的标准。未来的光伏发电系统必须像传统电厂一样提供全方位的服务，如电网故障下的低压穿越（LVRT）和电网支持服务。为了应对未来的挑战，本文对三种主流的单相无变压器光伏逆变器在电网故障下的LVRT性能进行了研究。还讨论了无功注入的控制策略。选择的逆变器有双极调制全桥逆变器、直流旁路全桥逆变器和高效可靠逆变器概念（HERIC）。最后以1kw单相并网光伏系统为例进行了分析。测试证实，尽管HERIC逆变器在效率方面是最佳候选，但在电压骤降的情况下，它不是非常可行。其他拓扑结构能够在LVRT期间提供无功电流。还提供了这些逆变器的基准测试，这为选择合适的设备和进一步优化系统提供了可能性。
Transformerless photovoltaic (PV) inverters are going to be more widely adopted in order to achieve high efficiency, as the penetration level of PV systems is continuously booming. However, problems may arise in highly PV-integrated distribution systems. For example, a sudden stoppage of all PV systems due to anti-islanding protection may trigger grid disturbances. Thus, standards featuring with ancillary services for the next generation PV systems are under a revision in some countries. The future PV systems have to provide a full range of services as what the conventional power plants do, e.g. Low Voltage Ride-Through (LVRT) under grid faults and grid support service. In order to map future challenges, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults are explored in this paper. Control strategies with reactive power injections are also discussed. The selected inverters are the full-bridge inverter with bipolar modulation, full-bridge inverter with DC bypass and the Highly Efficient and Reliable Inverter Concept (HERIC). A 1 kW single-phase grid-connected PV system is analyzed to verify the discussions. The tests confirmed that, although the HERIC inverter is the best candidate in terms of efficiency, it is not very feasible in case of a voltage sag. The other topologies are capable of providing reactive current during LVRT. A benchmarking of those inverters is also provided, which offers the possibility to select appropriate devices and to further optimize the system.