基于希尔伯特—黄变换算法的微电网孤岛检测方法研究

发布时间：2018-02-24 19:08

本文关键词： 分布式发电系统孤岛现象希尔伯特-黄变换被动检测法　出处：《哈尔滨理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：孤岛(Islanding)现象是指当电网系统失去传统集中供电方式的支撑后，区域内的本地负载功率由分布式发电系统供给的独立运行状态。孤岛现象可能会引起二次重合闸，甚至对微电网系统、负载和供电系统带来损坏。因此，为保证电力系统安全稳定运行，确保电能质量，需要及时检测出孤岛状态，并将分布式发电系统从公共耦合点(Point of commoncoupling，PCC)断开或者优化分布式发电系统的组合和供电模式继续对负荷进行供电。微电网孤岛现象的检测是并网逆变器系统的重要功能之一，自动切断或者重新优化分布式发电系统的过程也是以孤岛检测为前提的，检测性能的好坏直接影响设备的安全运行以及微电网技术的推广与应用。本文总结现有微电网孤岛检测方法的基础上，把时频分析方法移植应用在孤岛检测课题，提出基于希尔伯特-黄变换(Hilbert-Huang Transform，HHT)算法的被动检测法。主要原理是通过对公共耦合点处电压信号进行微观分量(微电网由并网到孤岛切换过程中电压信号高频谐波分量)的提取和识别。主要依据是电能质量在公共耦合点逆变器端和主网端不相等原理，随着微电网并网状态切换到孤岛状态的过程，电能质量的谐波成分会更加凸显。具体方法实施首先是PPC点电压信号经验模态分解(Empirical ModeDecomposition，EMD)和Hilbert变换，然后是计算奇异点的位置坐标，确定孤岛现象产生时刻。应用PSCAD/EMTDC和MATLAB/SIMULINK软件，仿真光伏分布式发电系统，实现并网运行与孤岛运行的平滑切换。人为设定多种试验条件下，例如，电网电压暂降，多类型负载运行、负荷的投切等，最终仿真的结果验证了HHT算法应用于微电网孤岛检测问题的有效性与准确性，，能够迅速检测到孤岛现象。
[Abstract]:The phenomenon of islanding refers to the independent operation state of the local load power in the region provided by the distributed generation system when the power system loses the support of the traditional centralized power supply mode. The phenomenon of isolated island may cause secondary reclosing, even damage to microgrid system, load and power supply system. Therefore, in order to ensure the safe and stable operation of power system and ensure the power quality, it is necessary to detect the isolated island state in time. The distributed generation system is disconnected or optimized from the point of common coupling point of common coupling PCCs and the power supply mode of the distributed generation system continues to supply the load. The detection of islanding phenomenon in microgrid is one of the important functions of grid-connected inverter system. The process of automatically cutting off or reoptimizing distributed generation system is also based on islanding detection. The detection performance directly affects the safe operation of the equipment and the popularization and application of microgrid technology. Based on the summary of the existing detection methods of isolated islands in microgrid, the time-frequency analysis method is transplanted to the islanding detection subject. A passive detection method based on Hilbert-Huang transform HHT (Hilbert-Huang transform) algorithm is proposed in this paper. The main principle is to carry out the micro-component of voltage signal at common coupling point (high frequency harmonics of voltage signal in the process of switching from grid-connected to islanding in microgrid). Is based on the principle that the power quality is unequal between the inverter and the main network at the common coupling point. The harmonic components of power quality will become more prominent with the process of switching to the isolated island state in the grid-connected state of microgrid. Firstly, empirical mode decomposition (EMD) and Hilbert transform of PPC point voltage signal are implemented, then the position coordinates of singular points are calculated, and the time of island phenomenon is determined. Using PSCAD/EMTDC and MATLAB/SIMULINK software, the distributed photovoltaic generation system is simulated. Realize smooth switching between grid-connected operation and islanding operation. Under a variety of artificial test conditions, such as voltage sag, multi-type load operation, load switching and so on, Finally, the simulation results verify the validity and accuracy of the HHT algorithm applied to the detection of isolated islands in microgrid, and the phenomenon of isolated islands can be detected quickly.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM732

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