光伏發(fā)電系統(tǒng)低電壓穿越技術的研究
發(fā)布時間：2019-01-22 15:55
【摘要】：隨著光伏并網電站安裝容量不斷上升，光伏并網系統(tǒng)在電網故障情況下的應對能力變得尤為重要，國家規(guī)定光伏發(fā)電系統(tǒng)在電網電壓跌落一定時間段內不能脫網運行，并對電網提供一定的無功支撐。本文研究電網電壓跌落時光伏發(fā)電系統(tǒng)的低電壓穿越技術，提高系統(tǒng)穩(wěn)定性和應對故障能力，并采用MATLAB軟件進行仿真分析。 本文建立了光伏并網逆變器在ABC三相靜止坐標系、αβ兩相靜止坐標系和dq旋轉坐標系下的數學模型，從光伏并網逆變器的拓撲結構和工作原理著手，分析了傳統(tǒng)的光伏并網逆變器的控制策略，分析了同步PI電流控制法，，即在同步旋轉坐標系下，采用前饋解耦控制方法，以固定開關頻率實現交流側電流控制。該控制策略結構簡單，參數設計容易，但需在電網電壓三相對稱環(huán)境下使用。本文在傳統(tǒng)控制策略基礎上建立光伏并網逆變器數學模型，即在傳統(tǒng)電壓外環(huán)、電流內環(huán)雙閉環(huán)控制策略的基礎上增加并網電流負序內環(huán)控制，在電網三相不對稱時提高逆變器的適應能力，再結合DC-DC控制實現光伏發(fā)電系統(tǒng)的低電壓穿越。 本文提出一種用超級電容儲能的低電壓穿越方法，在電網電壓跌落期間繼續(xù)保持光伏陣列的輸出，逆變器直流端的冗余電量儲存到超級電容當中，在保持了光伏發(fā)電系統(tǒng)發(fā)電量的同時實現低電壓穿越。采用Matlab/Simulink軟件平臺，搭建了基于低電壓穿越技術的光伏發(fā)電系統(tǒng)仿真模型，進行相應的仿真實驗。該方法既有較快的電流響應速度和系統(tǒng)恢復速度，又能儲存直流側部分冗余電量。在電壓跌落期間光伏逆變器能夠并網運行，還能根據電網需要輸送一定量的無功功率以支撐并網點電壓，減少光伏系統(tǒng)的脫網給電網帶來的沖擊。最后和相關企業(yè)合作對低電壓穿越技術的仿真模型的正確性進行實驗驗證，實驗結果表明該低電壓穿越技術是可行的。
[Abstract]:With the increasing installation capacity of grid-connected PV power station, the ability of photovoltaic grid-connected system to deal with the power grid fault becomes particularly important. The state stipulates that the photovoltaic power generation system can not be removed from the grid in a certain period of time when the grid voltage drops. And provide certain reactive power support to the power grid. In this paper, the low voltage traversing technology of photovoltaic power generation system with voltage drop is studied to improve the stability and fault response ability of the system, and the simulation analysis is carried out by using MATLAB software. In this paper, the mathematical models of photovoltaic grid-connected inverter in ABC three-phase stationary coordinate system, 偽 尾 two-phase stationary coordinate system and dq rotating coordinate system are established. The topology and working principle of photovoltaic grid-connected inverter are discussed. The control strategy of the traditional photovoltaic grid-connected inverter is analyzed, and the synchronous PI current control method is analyzed. In the synchronous rotating coordinate system, the feedforward decoupling control method is used to realize AC side current control with fixed switching frequency. The control strategy is simple in structure and easy in parameter design, but it needs to be used in the three-phase symmetrical environment of grid voltage. In this paper, the mathematical model of photovoltaic grid-connected inverter is established on the basis of traditional control strategy, that is, adding grid-connected current negative sequence inner loop control on the basis of traditional voltage outer loop and current inner loop double closed loop control strategy. The adaptive ability of inverter is improved when the power grid is three phase asymmetry, and the low voltage traversing of photovoltaic generation system is realized with DC-DC control. In this paper, a low voltage traversing method using super capacitor to store energy is proposed. The output of photovoltaic array is maintained during the voltage drop of the power grid, and the redundant power at the DC end of the inverter is stored in the super capacitor. Low voltage traversing is realized at the same time as the photovoltaic power generation system is maintained. The simulation model of photovoltaic power generation system based on low voltage traversing technology is built by using Matlab/Simulink software platform and the corresponding simulation experiments are carried out. This method not only has faster current response speed and system recovery speed, but also can store part of the DC side redundant power. During the voltage drop the photovoltaic inverter can be connected to the grid and can transport a certain amount of reactive power according to the need of the power grid to support and network voltage so as to reduce the impact to the grid caused by the de-grid of the photovoltaic system. Finally, the correctness of the simulation model of low-voltage traversing technology is verified by experiments in cooperation with relevant enterprises. The experimental results show that the low-voltage traversing technology is feasible.
【學位授予單位】：湘潭大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM464;TM615
本文編號：2413360
[Abstract]:With the increasing installation capacity of grid-connected PV power station, the ability of photovoltaic grid-connected system to deal with the power grid fault becomes particularly important. The state stipulates that the photovoltaic power generation system can not be removed from the grid in a certain period of time when the grid voltage drops. And provide certain reactive power support to the power grid. In this paper, the low voltage traversing technology of photovoltaic power generation system with voltage drop is studied to improve the stability and fault response ability of the system, and the simulation analysis is carried out by using MATLAB software. In this paper, the mathematical models of photovoltaic grid-connected inverter in ABC three-phase stationary coordinate system, 偽 尾 two-phase stationary coordinate system and dq rotating coordinate system are established. The topology and working principle of photovoltaic grid-connected inverter are discussed. The control strategy of the traditional photovoltaic grid-connected inverter is analyzed, and the synchronous PI current control method is analyzed. In the synchronous rotating coordinate system, the feedforward decoupling control method is used to realize AC side current control with fixed switching frequency. The control strategy is simple in structure and easy in parameter design, but it needs to be used in the three-phase symmetrical environment of grid voltage. In this paper, the mathematical model of photovoltaic grid-connected inverter is established on the basis of traditional control strategy, that is, adding grid-connected current negative sequence inner loop control on the basis of traditional voltage outer loop and current inner loop double closed loop control strategy. The adaptive ability of inverter is improved when the power grid is three phase asymmetry, and the low voltage traversing of photovoltaic generation system is realized with DC-DC control. In this paper, a low voltage traversing method using super capacitor to store energy is proposed. The output of photovoltaic array is maintained during the voltage drop of the power grid, and the redundant power at the DC end of the inverter is stored in the super capacitor. Low voltage traversing is realized at the same time as the photovoltaic power generation system is maintained. The simulation model of photovoltaic power generation system based on low voltage traversing technology is built by using Matlab/Simulink software platform and the corresponding simulation experiments are carried out. This method not only has faster current response speed and system recovery speed, but also can store part of the DC side redundant power. During the voltage drop the photovoltaic inverter can be connected to the grid and can transport a certain amount of reactive power according to the need of the power grid to support and network voltage so as to reduce the impact to the grid caused by the de-grid of the photovoltaic system. Finally, the correctness of the simulation model of low-voltage traversing technology is verified by experiments in cooperation with relevant enterprises. The experimental results show that the low-voltage traversing technology is feasible.
【學位授予單位】：湘潭大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM464;TM615
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