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1、南京航空航天大学硕士学位论文 i i 摘 要 随着经济的发展，电力需求与日剧增，环境影响日益严重，光伏发电、风力发电等新能源发电系统，已经广泛应用于生产、生活中。孤岛效应是并网供电系统中的一种特殊的故障状态，它是指当电网由于电气故障、误操作等原因导致供电中断时，并网发电系统未能检测出停电状态并脱离电网，持续向电网供电，使并网发电系统和周围的负载组成了一个电力公司无法掌握的自给供电孤岛。孤岛发生后，会对电力维修人员的安全和用电设备造成危害。 本文研究了一种基于频率正反馈的有源孤岛检测方法，这种方法可以快速的检测出孤岛现象，同时保证了系统正常工作时的稳定性和回馈电网的电能质量。 本文首先探讨了孤岛
2、检测技术研究的背景和现状，包括各种无源和有源检测方法及其优缺点，详细分析了有功功率和无功功率不匹配时所导致的电压和频率偏移，品质因数对频率偏移的影响，过/欠压、过/欠频保护的非检测区。然后针对现有孤岛检测方法存在检测盲区的问题，重点研究了基于正反馈的有源检测方法，包括电压正反馈和频率正反馈两种方法，分析了正反馈机理，通过仿真比较研究了两种方法的优缺点。为验证本文所研究的孤岛检测方法，介绍了并网逆变器的电路结构和国内外并网标准，比较了多种并网控制方法，设计了一台以TMS320F2812 DSP 芯片为控制核心， 采用的三态滞环电流控制策略的原理样机， 并且给出了数字锁相和孤岛检测的程序流程图，仿
3、真和实验结果均验证了系统方案的可行性和正确性。 关键词：关键词：并网逆变器，孤岛检测，检测盲区，频率正反馈 并网系统孤岛检测方法的研究 ii ii Abstract Concerning the rising cost of electricity, and environmental impact, smaller environmentally-friendly power sources are extensively used, such as photovoltaic, or wind-driven. If a fault takes place or a breaker is op
4、en, all the circuits downstream would be de-energized. However this is not the case when Distributed Generation is used. The islanding problem is defined as a continuation of operation of a grid-connected inverter after the grid has been turned off. Under fault condition, an island condition with po
5、wer generation and consumption is undesirable for a number of reasons including safety hazards to utility personnel, and potential damage to equipment. Thus islanding detection methods (IDM) must be developed and tested. The goal of this thesis is to investigate a method used in an inverter based on
6、 DG. The active IDM based on frequency positive feedback can measure the island status at high speed and accuracy, and ensure the power quality recycling to the grid. This thesis introduces the background and development of the anti-islanding techniques, including passive and active IDMs. The power
7、imbalance would result in the shift of voltage and frequency, the quality factor also affects the frequency shift, and the non-detection zone is obvious in OVP/UVP、OFP/UFP. All these problems will be deeply discuss. The thesis analyzes the advantages and disadvantages of different IDMs, and proposes
8、 active IDMs based on the positive feedback, including voltage positive feedback and frequency positive feedback. Comparing the two methods, the frequency positive feedback is more adequate, and deep discussion is provided. Then the grid-connected structure and standard are introduced. Three-lever h
9、ysteresis current control is chosen as the main functions of inverter and simulated with matlab. A TMS320F2812 DSP based prototype is designed including the program of digital phase lock loop and anti-islanding. Simulation and experimental results are presented to corroborate the theoretical analysi
10、s. Key words: grid-connected inverter, anti-islanding, non-detection zone, frequency positive feedback 南京航空航天大学硕士学位论文 v v 图、表清单 图 1.1 并网系统等效模型.4 图 1.2 孤岛测试电路 .8 图 2.1 孤岛系统原理电路.10 图 2.2 电网跳闸后的电路状态.11 图 2.3 过/欠压、过/欠频保护的 NDZ.11 图 2.4 主电路仿真图 .13 图 2.5 无功不匹配较大时仿真波形.14 图 2.6 无功不匹配较小时仿真波形.14 图 2.7 有功不匹配较大时仿真波形.15 图 2.8 有功不匹配较小时仿真波形.15 图 2.9invloadPP（0 136invP P.= ）.17 图 2.10invloadPP.21 图 2.13 agVV.21 图 2.14 电压正反馈仿真波形.21 图 2.15 频率正反馈检测方法原理图.22 图 2.16 功率严重不匹配仿真波形.24 图 2.17 功率匹配仿真波形（未加频率正反馈扰动）.24 图
