光伏逆变器的并网研究

发布时间：2018-06-20 00:57

本文选题：超短期电力负荷 + 并网　；参考：《河北联合大学》2014年硕士论文

【摘要】：如今在能源日渐短缺、消耗严重的背景下，人们开始逐步关注可再生能源的利用。光能作为最环保的可再生能源，其主要利用形式是光伏并网发电，具有良好的发展前景。以单相双级式光伏并网逆变器为研究对象，根据电力负荷的预测情况，对光伏逆变器分别采取并网和断网的措施。在并网时主要研究并网控制策略，断网时主要研究孤岛检测。首先对超短期电力负荷值进行聚类分析，并在此基础上对各个时间段的超短期负荷值的变化情况进行预测，根据变化情况判断光伏逆变器是否需要并网。当公共电网中用电负荷比较多时，，需要增加额外的供电设备时，为了保证负荷的供电可靠性，可以将光伏逆变器和电网并联，一起向负荷供电。当公共电网中用电负荷较少时，为了节省资源，光伏逆变器可以与电网断开连接，由光伏逆变器组成的电源仍然和本地负载相连，并继续供电。然后在并网过程中，针对单相双级式光伏并网逆变器DC/DC变换环节与DC/AC变换环节分别展开研究，重点是控制算法的研究及改进。在DC/DC变换环节研究光伏阵列、Boost电路的特性，重点探讨最大功率点跟踪（MPPT）的原理和控制方法。DC/AC变换环节主要由逆变环节、滤波环节和控制环节组成，在保证电网电压和并网电流同频同相的基础上，重点研究控制环节。针对电流滞环控制和基于单极性SPWM的电流控制两种方法的缺点，分别在控制算法上做出改进，提高控制性能。最后在光伏逆变器断网时，针对孤岛效应分析其产生的原理，在此基础上研究孤岛检测方法。常规的孤岛检测法分为被动式检测和主动式检测，被动式孤岛检测有比较大的检测盲区，为了减小盲区，引入主动式孤岛检测。重点研究两种主动式孤岛检测方法：主动移频法和电压正反馈法。两种方法都有各自的特点，在不同应用场合选用不同的方法，可以有效的避免孤岛所带来的危害。
[Abstract]:Nowadays, in the background of energy shortage and serious consumption, people begin to pay attention to the use of renewable energy. As the most environment-friendly renewable energy, light energy is mainly used in grid-connected photovoltaic power generation, which has a good development prospect. The single-phase two-stage photovoltaic grid-connected inverter is taken as the research object. According to the forecasting of power load, the grid-connected and grid-disconnected measures are adopted for the photovoltaic inverter respectively. The control strategy of grid-connected network is mainly studied while the detection of isolated islands is mainly studied when the network is broken. Based on the clustering analysis of ultra-short-term power load value, the change of ultra-short-term load value in each time period is forecasted, and the grid connection of photovoltaic inverter is judged according to the change. In order to ensure the reliability of power supply, the photovoltaic inverter and the power grid can be connected in parallel to supply the load together. In order to save resources, the PV inverter can be disconnected from the power grid when the power load in the public network is low, and the power supply composed of the photovoltaic inverter is still connected to the local load and continues to supply power. Then in the grid-connected process, the DC- / DC and DC- / AC conversion links of single-phase two-stage photovoltaic grid-connected inverter are studied, with emphasis on the research and improvement of the control algorithm. The characteristics of photovoltaic array boost circuit are studied in the DC / DC conversion link. The principle and control method of maximum power point tracking (MPPTT) are mainly discussed. The DC / AC conversion link is mainly composed of inverter link, filter link and control link. On the basis of ensuring the same frequency and phase of grid voltage and current, the control link is studied emphatically. Aiming at the shortcomings of current hysteresis control and current control based on unipolar SPWM, the control algorithm is improved to improve the control performance. Finally, the principle of islanding effect is analyzed when the photovoltaic inverter is cut off, and the detection method of islanding is studied. The conventional islanding detection method is divided into passive detection and active detection. Passive islanding detection has a relatively large blind area. In order to reduce the blind area, active islanding detection is introduced. Two active island detection methods, active frequency shift method and voltage positive feedback method, are studied. The two methods have their own characteristics. Choosing different methods in different applications can effectively avoid the harm caused by isolated islands.
【学位授予单位】：河北联合大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

【参考文献】