準(zhǔn)Z源級(jí)聯(lián)多電平光伏逆變器控制方法的研究
[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(xué)位授予單位】:北京交通大學(xué)
【學(xué)位級(jí)別】:博士
【學(xué)位授予年份】:2014
【分類(lèi)號(hào)】:TM464
【參考文獻(xiàn)】
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