Control of line interactive UPS systems in a Microgrid
Control of line interactive UPS systems in a Microgrid
复制标题
微电网中线路交互式 UPS 系统的控制
DOI：
10.1109/isie.2011.5984371
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
S. Sharkh
中科院分区：
文献类型：
--
作者：
M. Abusara;S. Sharkh
研究微电网中线交互不间断电源(UPS)系统的控制问题。在并网模式下，可以从电网输入电能为电池充电，也可以将电能注入电网以增加微电网提供的电力。在孤岛模式下，UPS与其他电源并行提供本地临界负荷。潮流控制使用频率和电压下降技术，以确保在并网和并联孤岛运行模式之间的无缝转换。当电力从电网输入时，调节直流连接电压的外部电压控制器为内部潮流控制器设定功率需求。利用小信号分析方法设计了外环电压环，并对内环潮流控制器的动态特性进行了建模。由于DC链路电容有限，因此需要仔细选择下垂系数，以限制暂态循环有功功率从电网到UPS模块或从一个UPS模块到另一个UPS模块。用实时积分的方法取代了传统的基于低通滤波的有功和无功测量方法，提高了控制器的响应速度。在并网模式下利用虚拟阻抗来改善输出电流THD。给出了两个60kW线路互动式UPS模块的实验结果，验证了设计的正确性。
This paper is concerned with the control of a line interactive Uninterruptable Power Supply (UPS) system in a Microgrid. In grid connected mode, power can be imported from the grid to charge the battery or it can be injected into the grid to boost the power supplied by the Microgrid. In island mode, the UPS supplies local critical load in parallel with other sources. Power flow is controlled using the frequency and voltage drooping technique to ensure seamless transfer between grid connected and parallel islanding modes of operation. When the power is imported from the grid, an outer voltage controller that regulates the DC link voltage sets the power demand for an inner power flow controller. The outer voltage loop is designed with the aid of small signal analysis which has been used to model the dynamics of the inner power flow controller. Due to the limited DC link capacitance, the drooping coefficients are chosen carefully to limit transient circulating active power from the grid to the UPS module or from one UPS module to another. The traditional way of measuring active and reactive power which is based on using a low pass filter is replaced by a real time integration method which is shown to improve the response of the controller. A virtual impedance is utilized in grid-connected mode to improve output current THD. Experimental results of two 60kW line interactive UPS modules are provided to validate the design.