基于最小能量补偿控制的微网动态电压恢复器

Dynamic Voltage Restorer in Micro-grid Based on a Minimum Energy Compensation Control Scheme

针对目前微网在并网运行模式下或由并网向孤岛运行模式切换中出现的短时电压扰动问题,建立了适合于微网不同运行模式下的动态电压恢复器(DVR)模型。微网中DVR以传统的混合级联H桥多电平逆变器拓扑结构为主体框架,采用一种改进的逆变器最小能量补偿控制策略,该方法物理意义明确,数学推导清晰,在确定DVR最小注入功率角时简洁方便,并能够进一步减少DVR在工作时的能量消耗,延长补偿时间;DVR以微网中自带的风电机组-蓄电池为直流储能单元,降低运行成本;当微网运行于孤岛模式下,DVR工作在微电源方式,可以减少主网的电能供给,提高DVR设备的利用率,实现节能减排。算例仿真结果说明了所提DVR模型的可行性。

In allusion to eliminate the short-term voltage disturbances appearing at the gridconnected operation mode or the switching between grid-connected operation mode and islanded operation mode of the micro-grid, a dynamic voltage restorer(DVR) model is proposed to meet the requirements of both islanded and grid-connected operation of micro-grid. The DVR structure is based on a conventional hybrid cascaded H-bridge multi-level inverter(MLI) topology, and a minimum energy compensation control scheme is proposed, which has characteristics of definite physical concept, distinct mathematical derivation and concise method in determining the angle of minimum injective active power. Moreover, it can further reduce the energy consumption of DVR at work, which could effectively prolong compensation time. Utilizing wind turbines-batteries units as DC energy storage component in micro-grid, the operation cost of the DVR is reduced; when the micro-grid work under islanded operation mode, the DVR can operate on micro-source mode, which can reduce the power supply from distribution network and be favorable for energy saving and emission reduction. The simulation results show the robustness and accuracy of the proposed DVR system.