Balancing of modular multilevel converters with unbalanced integration of energy storage devices
Balancing of modular multilevel converters with unbalanced integration of energy storage devices
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模块化多电平转换器与储能装置不平衡集成的平衡
DOI：
10.1109/epe.2016.7695265
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
M. Bakran
中科院分区：
文献类型：
--
作者：
Gerrit Henke;M. Bakran
在目前占主导地位的交流电网中，能量储备由旋转的同步发电机的惯性提供。在潜在的DC电网中，不存在这样的固有能量储备，因此需要额外的能量存储（ES）来确保电网稳定性。模块化多电平变流器（MMC）是一种用于高压直流输电网应用的新兴技术，它提供了一种将ES连接到电网的便捷方式。短串电池或超级电容器可以直接集成到MMC子模块中，从而创建启用ES的MMC，这降低了系统对单个ES电池故障的敏感性。由于将ES连接到子模块单元需要额外的电气设备（开关和/或电感器），因此减少具有集成ES的子模块的数量可以显著降低ES集成的额外成本。到目前为止，在大多数关于这一主题的研究中，假设所有MMC模块中存在ES。然而，ES使能MMC中的ES的量可以通过利用循环电流来减少，以实现具有和不具有集成ES的子模块之间的能量平衡。通过感应环形电流，能量可以在任何相臂之间转移，并且具有ES的相臂可以向没有ES的相臂供电。本检查的重点是由循环电流引起的附加半导体负载。它表明，只有一个非常小的增加，在半导体负载时，只有几个臂提供整个输出功率。
In the currently predominant AC-Grid, energy reserves are provided by the inertia of rotating synchronous generators. In a potential DC-Grid, there is no such inherent energy reserve and thus additional energy storage (ES) is required to ensure grid stability. The Modular Multilevel Converter (MMC) is an emerging technology for HVDC-Grid applications and offers a convenient way of connecting ES to the grid. Short strings of batteries or supercapacitors can be integrated directly into the MMC submodules, creating an ES enabled MMC, which reduces the susceptibility of the system to an individual ES cell failure. Since connecting ES to the submodule cells requires additional electrical devices (switches and/or inductors), reducing the number of submodules with integrated ES can significantly reduce the additional cost for ES integration. In most research conducted on this topic so far, the existence of ES in all MMC modules is assumed. However, the amount of ES in an ES enabled MMC can be reduced by utilizing circular currents to achieve energy balance between submodules with and without integrated ES. By inducing circular currents, energy can be transferred between any phase arms, and phase arms with ES can supply those without. The focus of this examination is the additional semiconductor load caused by the circular currents. It is shown that there is only a very small increase in the semiconductor load, when only a few arms supply the whole output power.