【摘要】：近年來,隨著一次能源的使用量日益加劇、能源的逐漸枯竭以及環(huán)境問題的日益惡化與凸顯,越來越多的清潔綠色可在再生能源逐漸顯露頭角,被越來越多的廣泛應用接入電網(wǎng)。在眾多的新型綠色能源中,光伏發(fā)電占了較大的比重,對于一個與電網(wǎng)互聯(lián)的以光伏發(fā)電為主體的分布式發(fā)電系統(tǒng),針對它的安全性與運行可靠性的要求及越來越高,那么針對于光伏發(fā)電系統(tǒng)的孤島檢測環(huán)節(jié)就顯得尤為重要,這也是電網(wǎng)與分布式發(fā)電系統(tǒng)互聯(lián)工作的最基本保障。同時,隨著光伏發(fā)電系統(tǒng)所接入的微電網(wǎng)規(guī)模越來越大,單臺逆變器的可承受功率容量已不滿足實際需要,多臺逆變器同時并聯(lián)工作的情況已然越來越多,因此針對于多機系統(tǒng)的孤島檢測也變得有實際工程應用的價值。首先,本文從孤島效應的定義出發(fā),闡述了它的發(fā)生原理及危害,探討了孤島效應發(fā)生的條件,介紹了國內(nèi)外通用的孤島檢測標準,進而引出孤島檢測的方法。主要有基于通信側和本地側兩種,本地側檢測方法又分為被動式檢測和主動式檢測,對這些方法的詳細介紹后比較出優(yōu)缺點和適用范圍,同時介紹了描述孤島檢測盲區(qū)的四種坐標模型。從主動式檢測法中選取常用的主動移頻式檢測法和主動移相式檢測法作為本文的研究重點。其次,分別對主動移頻式和主動移相式兩種方法作了深入探討,闡述其檢測原理,對各自的參數(shù)設計方案都分別進行了仿真驗證。對于主動移頻式探究了截斷系數(shù)選擇與電流畸變程度之間的關系;針對于由滑膜頻率偏移法引申而來的自動移相法的相位表達式加以簡化,并對其反饋系數(shù)通過引入模糊控制加以優(yōu)化和改進,并重新搭建模型驗證了改進算法的可行性。最后,由于越來越多的光伏發(fā)電系統(tǒng)接入電網(wǎng),多臺逆變器的并聯(lián)運行是大勢所趨。本文以兩臺逆變器作為討論對象,設計了四種逆變器組合方法:被動式與主動移頻式結合、主動移頻與帶正反饋的主動移頻相結合、主動移頻與主動移相式結合和兩臺主動移相式在帶有頻率檢測誤差時的并聯(lián)運行。分別討論了他們的相互內(nèi)在的聯(lián)系和影響、各自的檢測盲區(qū)并在各種參數(shù)設置和盲區(qū)內(nèi)外分別加以仿真驗證,以探究各種因素對多臺逆變器并聯(lián)運行孤島檢測性能的影響
[Abstract]:In recent years, with the increasing use of primary energy, the gradual depletion of energy and the worsening and highlighting of environmental problems, more and more clean green energy can be gradually revealed in renewable energy. It is more and more widely used to connect to the power grid. Among many new green energy sources, photovoltaic power generation accounts for a large proportion. For a distributed power generation system which is connected with the power grid, the security and operation reliability of the distributed generation system is becoming higher and higher. So the detection of isolated islands for photovoltaic power generation system is particularly important, which is the most basic guarantee of interconnection between power grid and distributed generation system. At the same time, with the increasing scale of microgrid connected to photovoltaic power generation system, the tolerable power capacity of a single inverter is no longer satisfied with the actual needs, and there are more and more cases of parallel operation of multiple inverters at the same time. Therefore, the islanding detection for multi-computer systems has become of practical engineering value. Firstly, from the definition of islanding effect, this paper expounds its occurrence principle and harm, discusses the conditions for the occurrence of islanding effect, introduces the common detection standards of islanding at home and abroad, and then leads to the method of islanding detection. There are two main methods based on the communication side and local side. The local side detection methods are divided into passive detection and active detection. After the detailed introduction of these methods, the advantages and disadvantages and the scope of application are compared. At the same time, four coordinate models are introduced to describe the blind area of isolated island detection. The active frequency shift detection and active phase shift detection are selected as the focus of this paper. Secondly, the two methods of active frequency shift and active phase shift are discussed in detail, the detection principle is expounded, and the design schemes of each parameter are verified by simulation. The relationship between the selection of truncation coefficient and the degree of current distortion is explored, and the phase expression of the automatic phase-shifting method derived from the synovial frequency shift method is simplified. The feedback coefficient is optimized and improved by introducing fuzzy control, and the feasibility of the improved algorithm is verified by reconstructing the model. Finally, because more and more photovoltaic power systems are connected to the power grid, the parallel operation of multiple inverters is the trend of the times. In this paper, two inverters are taken as the object of discussion. Four kinds of inverter combination methods are designed: passive and active frequency shifting, active frequency shifting and active frequency shifting with positive feedback. The combination of active frequency shift and active phase shift and the parallel operation of two active phase shifters with frequency detection error. Their internal relationship and influence are discussed respectively, and their blind areas are tested and simulated in various parameter settings and inside and outside blind areas respectively, in order to explore the influence of various factors on the detection performance of parallel operation isolated island of multiple inverters.
【學位授予單位】：東北農(nóng)業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM727;TM464

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本文編號：2249503