直流微电网混合型松弛终端分层控制策略

Hierarchical control strategy of hybrid-type slack terminal in DC micro-grid

为了合理使用不同类型的松弛终端调节直流微电网母线电压波动,提出了一种针对直流微电网中混合松弛终端的分层控制策略。基于锂电池存在最佳充放电循环深度、超级电容动态响应快和上级直流主母线功率大等特性,文中将超级电容作为缓冲单元,采用双锂电池为主要的能量单元(A、B),并用上级主母线作为后背支撑,构成完备的混合型松弛终端架构。通过分析,超级电容电压控制电池出力,在微电网系统处于动态平衡时,超级电容电压可以间接表征出直流母线电压波动的低频分量。因此文中利用超级电容电压来确定双锂电池出力,根据超级电容电压信号进行层级划分并设计四种工作模式,使各松弛终端得到能量的高效分配。实验结果验证了该控制策略的有效性。

In order to regulate the voltage fluctuation of the DC micro-grid by using different types of slack terminals, a hierarchical control strategy for hybrid-type slack terminal is proposed. Based on the characteristics of the optimal cycle depth of charging and discharging about lithium battery, the performances of high ramp rate about the super ca- pacitor and high power about the superior main DC bus, this paper takes the super capacitor as a buffer device, adopts the double lithium battery as the basic energy storage unit （ A, B） and takes the superior main DC bus as backup sup- port to construct a hybrid-type slack terminal. When the battery output is controlled according to the super capacitor voltage, through the analysis, the super capacitor voltage can be used to characterize the size of the low frequency component of the DC bus voltage fluctuation in a dynamic balance of DC micro-grid system. Thus this paper divides the hierarchy according to the signals of super capacitor voltage, and designs four working modes, to make every slack terminal can obtain energy allocation efficiently. The experimental results verify the effectiveness of the proposed con- trol strategy.