Discontinuous modulation method for isolating DC-DC converter to mitigate grid-side DC link voltage fluctuation

2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM) Pub Date : 2018-06-01 DOI:10.1109/SPEEDAM.2018.8445260

J. Korhonen, P. Silventoinen, William Giewont, D. Isaksson

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引用次数: 2

Abstract

This paper proposes a discontinuous modulation strategy of an isolating DC-DC converter on the photovoltaic plant side to reduce the grid side inverter DC link voltage fluctuation. Cascaded H-bridges (CHB) can be used to connect a photovoltaic plant directly to a medium voltage grid without a grid frequency transformer, as the topology has an inherent requirement of having an isolation between the series connected cells. Cascaded H-bridges has a feature that the DC link voltages of the cells have a voltage fluctuation at twice the output frequency. This fluctuation can be reduced by limiting the power towards the capacitor during intervals when the output power is low. The effect of discontinuous mode interval length on the photovoltaic side is studied. The benefits of the proposed method are reduced switching losses at the isolating DC-DC converter and reduced switching losses at the grid inverter due to smaller peak voltages of the DC links.

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隔离DC-DC变换器以减轻电网侧直流链路电压波动的不连续调制方法

为了减小电网侧逆变器直流链路电压波动，提出了光伏侧隔离型DC-DC变换器的不连续调制策略。级联h桥(CHB)可用于将光伏电站直接连接到中压电网，而无需电网频率变压器，因为该拓扑结构具有在串联连接的单元之间具有隔离的固有要求。级联h桥具有一个特点，即单元的直流链路电压在输出频率的两倍处有电压波动。当输出功率较低时，可以通过在间隔时间内限制对电容器的功率来减小这种波动。研究了不连续模式间隔长度对光伏侧的影响。该方法的优点是降低了隔离DC-DC变换器的开关损耗，并且由于直流链路的峰值电压较小，降低了电网逆变器的开关损耗。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)

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