準Z源級聯(lián)多電平光伏逆變器控制方法的研究
發(fā)布時間：2018-11-24 11:06
【摘要】：隨著光伏產(chǎn)業(yè)扶持政策的不斷出臺,全球太陽能光伏發(fā)電技術正持續(xù)快速發(fā)展。然而,光伏發(fā)電易受溫度和光照等自然條件影響,具有隨機性、不穩(wěn)定性、季節(jié)性等特點。單個光伏電池電壓較低,需要串聯(lián)很多個電池滿足用戶電壓等級要求。對于這種直接串聯(lián)的結構,光伏電池板局部陰影和失配將嚴重降低整個系統(tǒng)的發(fā)電效率。為了克服這個問題,已有大量研究采用級聯(lián)多電平逆變器(CMI),將光伏板分配給多個獨立的H橋模塊,對各模塊分別進行最大功率跟蹤來降低光伏電池板局部陰影和失配導致的不利,以改善發(fā)電效率。但傳統(tǒng)H橋逆變模塊缺少升壓功能,光伏電池板最大功率點電壓的不同將導致不平衡的直流母線電壓；并且在光伏電壓寬范圍變化的情況下,對逆變器容量的要求倍增。近年,有研究提出在每個H橋模塊嵌入DC-DC變換器來平衡直流母線電壓,但是,附加的大量DC-DC變換器,不僅增加了功率電路和控制的復雜性,增加了成本,而且降低了系統(tǒng)效率。 新近提出的準Z源級聯(lián)多電平逆變器(qZS-CMI),將準Z源網(wǎng)絡嵌入傳統(tǒng)CMI,不僅改善了H橋模塊無法升壓的不足,且具有準Z源逆變器(qZSI)的特點。將其應用于光伏發(fā)電時,各H橋模塊均以單級功率變換實現(xiàn)升壓及直流-交流轉(zhuǎn)換,獨立地控制直流母線電壓；逆變橋同一橋臂的上下開關管可同時導通而不損壞；可實現(xiàn)分布式最大功率跟蹤；比傳統(tǒng)CMI減少1/3的模塊；等等。這些都有助于光伏發(fā)電系統(tǒng)成本的降低、可靠性的提高,受到了越來越多的關注。然而,對qZS-CMI這一新型拓撲的研究尚處于初步階段,缺乏較深入的分析與控制設計。 本文重點研究準Z源級聯(lián)多電平光伏逆變器的控制方法,提出了兩種脈寬調(diào)制策略,以及系統(tǒng)并網(wǎng)控制方法。具體如下： 首先,建立了較詳細的準Z源H橋光伏逆變模塊模型。目前,在由qZS-CMI構成的光伏系統(tǒng)方面,尚無系統(tǒng)完整的模型來指導其參數(shù)選取和控制器設計。本文以準Z源H橋光伏逆變模塊為對象,考慮光伏板終端電容和兩倍頻脈動功率影響,建立其統(tǒng)一的狀態(tài)空間方程,推導了兩倍頻脈動分量模型和系統(tǒng)動態(tài)傳遞函數(shù)模型。依據(jù)兩倍頻脈動分量模型,分析了阻抗參數(shù)對低頻脈動分量的影響,設計了抑制兩倍頻脈動的整套阻抗元件參數(shù)；動態(tài)模型則為設計獨立的直流母線電壓平衡控制提供依據(jù)。 其次,提出了qZS-CMI的SVM方法。通過比較現(xiàn)有兩電平三相qZSI的空間矢量調(diào)制(SVM),提出一種qZSI的SVM方法,以降低電感電流脈動、提高效率；依此為基礎,結合qZS-CMI模塊化特點,將兩電平三相qZSI的SVM擴展到qZS-CMI,提出qZS-CMI的SVM方法,并以仿真和實驗驗證了所提出的方法。與qZS-CMI已有的移相正弦脈寬調(diào)制(PS-SPWM)相比,新調(diào)制方法具有電壓利用率高、占用資源少、模塊化、易于擴展至任意級聯(lián)數(shù)目的優(yōu)點。 再次,提出了qZS-CMI的移相脈沖寬度幅值調(diào)制(PS-PWAM),以減少qZS-CMI的開關動作,降低功率損耗。研究了該調(diào)制方式下的損耗評估方法,比較了PS-PWAM和PS-SPWM兩種方法控制時qZS-CMI的功率損耗。仿真與實驗驗證了所提出的PS-PWAM方法,表明PS-PWAM可有效降低系統(tǒng)損耗,改善效率。此外,分析了以新型寬能隙碳化硅(SiC)二極管作準Z源二極管,進一步從器件上減少損耗的情況。 最后,提出了光伏qZS-CMI的并網(wǎng)控制策略,包括分布式MPPT、獨立的直流母線電壓平衡控制,及單位功率因數(shù)并網(wǎng)控制。先以單相系統(tǒng)為對象,建立了其系統(tǒng)級傳遞函數(shù)模型,詳細設計了各調(diào)節(jié)器,以適應寬范圍的光伏電壓變化與實現(xiàn)高質(zhì)量并網(wǎng)；再將所提出的控制方法進行擴展,研究了三相系統(tǒng)的控制策略。 本文力從拓撲級、調(diào)制級、控制級和器件級等方面,對準Z源級聯(lián)多電平光伏逆變系統(tǒng)進行研究,分別以仿真和實驗驗證提出的控制方法,其研究成果將促進新型太陽能光伏逆變器的應用,滿足高質(zhì)量的供電用電需求。
[Abstract]:With the development of the support policy of the PV industry, the global solar PV power generation technology is developing rapidly. However, the photovoltaic power generation is easy to be influenced by natural conditions such as temperature and light, and has the characteristics of randomness, instability, and seasonality. The voltage of a single photovoltaic cell is low, and a plurality of batteries in series are required to meet the requirements of the voltage level of the user. For such a direct series configuration, the local shading and mismatch of the photovoltaic panel will significantly reduce the power generation efficiency of the overall system. In order to overcome this problem, a large number of cascaded multilevel inverters (CMI) are used to distribute the photovoltaic panel to a plurality of independent H-bridge modules, and the modules are respectively subjected to the maximum power tracking to reduce the disadvantages caused by the local shading and the mismatch of the photovoltaic cell panel, so as to improve the power generation efficiency. However, the traditional H-bridge inverter module lacks the step-up function, and the difference of the maximum power point voltage of the photovoltaic cell panel will lead to an unbalanced DC bus voltage; and in the case of the variation of the wide range of the photovoltaic voltage, the requirement of the capacity of the inverter is multiplied. In recent years, it has been proposed to balance the DC bus voltage by embedding the DC-DC converter in each H-bridge module, but the additional large number of DC-DC converters not only increases the complexity of the power circuit and control, increases the cost, but also reduces the system efficiency. A new quasi-Z-source cascaded multilevel inverter (qZS-CMI) is proposed to embed the quasi-Z-source network into the traditional CMI, which not only improves the shortage of the H-bridge module, but also has a quasi-Z-source inverter (qZSI). The invention is characterized in that when applied to the photovoltaic power generation, each H-bridge module realizes the step-up and direct current-alternating current conversion with a single-stage power conversion, and independently controls the DC bus voltage; the upper and lower switching tubes of the same bridge arm of the inverter bridge can be simultaneously conducted without damage; and the distributed maximum power can be realized. tracking; a module that reduces 1/ 3 of the conventional CMI; and the like. These all contribute to the reduction of the cost of the photovoltaic power generation system, the improvement of the reliability, However, the research on the new topology of qZS-CMI is still in the preliminary stage and lacks in-depth analysis and control. This paper mainly studies the control method of quasi-Z-source cascade multi-level photovoltaic inverter, and puts forward two pulse-width modulation strategies and the system. Network control method. Specific as follows: First, a more detailed quasi-Z-source H-bridge is established PV inverter module model. At present, there is no system complete model to guide its parameters in the photovoltaic system composed of qZS-CMI in this paper, a quasi-Z-source H-bridge photovoltaic inverter module is used as an object, and a unified state space equation is established, and a double-frequency ripple component model and a system are derived, taking into account the influence of the capacitance of the photovoltaic panel terminal and the double-frequency ripple power, and establishing a uniform state space equation. The dynamic transfer function model is based on the two-frequency ripple component model, the influence of the impedance parameter on the low-frequency ripple component is analyzed, the whole set of impedance element parameters are designed to suppress the double-frequency ripple, and the dynamic model is a design independent DC bus voltage. Balance control provides a basis. Second, qZ is proposed The SVM method of S-CMI is proposed. By comparing the current two-level three-phase qZSI space vector modulation (SVM), an SVM method for qZSI is proposed to reduce the ripple of the inductor current and improve the efficiency. On the basis of this, the SVM of two-level three-phase qZSI is extended to qZS-CMI, and qZ is proposed. The SVM method of S-CMI and simulation and simulation Compared with the existing phase-shift sinusoidal pulse-width modulation (PS-SPWM) of qZS-CMI, the new modulation method has the advantages of high voltage utilization ratio, less occupied resources, modularization and easy expansion. Exhibitions to any of the advantages of any cascade. Again, a phase shift pulse width amplitude modulation (PS-PWAM) for qZS-CMI is proposed to reduce qZS-C The power loss is reduced by the switching action of the MI. The loss evaluation method in this modulation mode is studied. The two methods of PS-PWAM and PS-SPWM are compared. The power loss of qZS-CMI is verified by simulation and experiment, which shows that the PS-PWAM method in addition, a novel wide-gap silicon carbide (SiC) diode is used as a quasi-Z-source diode, Finally, the grid control strategy of the photovoltaic qZS-CMI is put forward, including the distributed MPPT and the independent DC bus. The system-level transfer function model is established based on the single-phase system, and each regulator is designed in detail so as to meet the wide range of PV voltage change and realize high quality and network; and then the proposed control method In this paper, the control strategy of the three-phase system is studied and the control strategy of the three-phase system is studied in this paper. The power of the three-phase system is studied from the aspects of the topological level, the modulation stage, the control level and the device level, and the control method proposed by the simulation and the experimental verification is carried out respectively. The research results will promote the new type of solar light
【學位授予單位】：北京交通大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM464
[Abstract]:With the development of the support policy of the PV industry, the global solar PV power generation technology is developing rapidly. However, the photovoltaic power generation is easy to be influenced by natural conditions such as temperature and light, and has the characteristics of randomness, instability, and seasonality. The voltage of a single photovoltaic cell is low, and a plurality of batteries in series are required to meet the requirements of the voltage level of the user. For such a direct series configuration, the local shading and mismatch of the photovoltaic panel will significantly reduce the power generation efficiency of the overall system. In order to overcome this problem, a large number of cascaded multilevel inverters (CMI) are used to distribute the photovoltaic panel to a plurality of independent H-bridge modules, and the modules are respectively subjected to the maximum power tracking to reduce the disadvantages caused by the local shading and the mismatch of the photovoltaic cell panel, so as to improve the power generation efficiency. However, the traditional H-bridge inverter module lacks the step-up function, and the difference of the maximum power point voltage of the photovoltaic cell panel will lead to an unbalanced DC bus voltage; and in the case of the variation of the wide range of the photovoltaic voltage, the requirement of the capacity of the inverter is multiplied. In recent years, it has been proposed to balance the DC bus voltage by embedding the DC-DC converter in each H-bridge module, but the additional large number of DC-DC converters not only increases the complexity of the power circuit and control, increases the cost, but also reduces the system efficiency. A new quasi-Z-source cascaded multilevel inverter (qZS-CMI) is proposed to embed the quasi-Z-source network into the traditional CMI, which not only improves the shortage of the H-bridge module, but also has a quasi-Z-source inverter (qZSI). The invention is characterized in that when applied to the photovoltaic power generation, each H-bridge module realizes the step-up and direct current-alternating current conversion with a single-stage power conversion, and independently controls the DC bus voltage; the upper and lower switching tubes of the same bridge arm of the inverter bridge can be simultaneously conducted without damage; and the distributed maximum power can be realized. tracking; a module that reduces 1/ 3 of the conventional CMI; and the like. These all contribute to the reduction of the cost of the photovoltaic power generation system, the improvement of the reliability, However, the research on the new topology of qZS-CMI is still in the preliminary stage and lacks in-depth analysis and control. This paper mainly studies the control method of quasi-Z-source cascade multi-level photovoltaic inverter, and puts forward two pulse-width modulation strategies and the system. Network control method. Specific as follows: First, a more detailed quasi-Z-source H-bridge is established PV inverter module model. At present, there is no system complete model to guide its parameters in the photovoltaic system composed of qZS-CMI in this paper, a quasi-Z-source H-bridge photovoltaic inverter module is used as an object, and a unified state space equation is established, and a double-frequency ripple component model and a system are derived, taking into account the influence of the capacitance of the photovoltaic panel terminal and the double-frequency ripple power, and establishing a uniform state space equation. The dynamic transfer function model is based on the two-frequency ripple component model, the influence of the impedance parameter on the low-frequency ripple component is analyzed, the whole set of impedance element parameters are designed to suppress the double-frequency ripple, and the dynamic model is a design independent DC bus voltage. Balance control provides a basis. Second, qZ is proposed The SVM method of S-CMI is proposed. By comparing the current two-level three-phase qZSI space vector modulation (SVM), an SVM method for qZSI is proposed to reduce the ripple of the inductor current and improve the efficiency. On the basis of this, the SVM of two-level three-phase qZSI is extended to qZS-CMI, and qZ is proposed. The SVM method of S-CMI and simulation and simulation Compared with the existing phase-shift sinusoidal pulse-width modulation (PS-SPWM) of qZS-CMI, the new modulation method has the advantages of high voltage utilization ratio, less occupied resources, modularization and easy expansion. Exhibitions to any of the advantages of any cascade. Again, a phase shift pulse width amplitude modulation (PS-PWAM) for qZS-CMI is proposed to reduce qZS-C The power loss is reduced by the switching action of the MI. The loss evaluation method in this modulation mode is studied. The two methods of PS-PWAM and PS-SPWM are compared. The power loss of qZS-CMI is verified by simulation and experiment, which shows that the PS-PWAM method in addition, a novel wide-gap silicon carbide (SiC) diode is used as a quasi-Z-source diode, Finally, the grid control strategy of the photovoltaic qZS-CMI is put forward, including the distributed MPPT and the independent DC bus. The system-level transfer function model is established based on the single-phase system, and each regulator is designed in detail so as to meet the wide range of PV voltage change and realize high quality and network; and then the proposed control method In this paper, the control strategy of the three-phase system is studied and the control strategy of the three-phase system is studied in this paper. The power of the three-phase system is studied from the aspects of the topological level, the modulation stage, the control level and the device level, and the control method proposed by the simulation and the experimental verification is carried out respectively. The research results will promote the new type of solar light
【學位授予單位】：北京交通大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM464
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