本文選題：直流微電網(wǎng) + 直流母線電壓�。� 參考：《西南交通大學》2014年碩士論文

【摘要】：面對環(huán)境污染和能源短缺的雙重壓力,清潔經(jīng)濟的分布式發(fā)電技術得到了廣泛的應用。但大規(guī)模分布式電源的并網(wǎng)運行會對大電網(wǎng)的安全可靠運行造成不可忽略的影響。為了防止這一弊端,微電網(wǎng)的概念應運而生。微電網(wǎng)既能高效的利用新能源,又能參與電力市場管理,具有靈活性強,交互性好的特點。根據(jù)微電網(wǎng)中母線電流的性質,可以將微電網(wǎng)劃分為直流微電網(wǎng)、交流微電網(wǎng)以及交直流混合微電網(wǎng)三種類型。與后兩者相比,直流微電網(wǎng)具有效率高、損耗低、可控性強等優(yōu)點,但直流微電網(wǎng)由于容量有限,抗擾動能力弱,在運行條件發(fā)生變化時,容易引起直流母線電壓的波動和電能質量的降低。因此需要設計合適的能量管理控制策略維持母線電壓穩(wěn)定,管理微電網(wǎng)電能質量。論文從分布式電源的建模出發(fā),建立了直流微電網(wǎng)的控制模型,對直流微電網(wǎng)的分層能量管理控制策略進行了研究。 首先,闡述了光伏電源的工作原理,建立了光伏電源的工程實用模型,在此基礎上,采用爬山法對光伏電源的輸出進行了最大功率跟蹤,仿真結果表明,即使光照強度和環(huán)境溫度發(fā)生變化,光伏電源也能實現(xiàn)最大功率的輸出,驗證了最大功率跟蹤算法的有效性；分析了蓄電池的充放電動作原理,建立了完整的蓄電池充放電模型,仿真結果表明,該模型可以根據(jù)蓄電池的SOC狀態(tài)切換充放電動作,能夠良好的反映蓄電池的物理特性；介紹了雙向AC/DC變換器的工作原理,設計了解耦控制模型,從仿真結果可以看出,通過控制變換器在整流和逆變兩種工作狀態(tài)之間的切換,可以實現(xiàn)能量的雙向流動。 其次,根據(jù)直流微電網(wǎng)在不同運行模式下的工作特性,以母線電壓的大小為依據(jù),對光伏電源、蓄電池、雙向AC/DC變換器、負載分別設計了控制策略。其中,控制光伏電源工作在最大功率追蹤輸出和恒壓模式兩種運行狀態(tài)；設計了蓄電池的下垂控制策略,根據(jù)母線電壓的大小調節(jié)蓄電池的充放電功率；通過切換雙向AC/DC變換器的工作狀態(tài),實現(xiàn)能量在微電網(wǎng)和大電網(wǎng)之間的雙向流動；在系統(tǒng)重載的情況下采用切負載策略使母線電壓恢復到正常范圍。仿真結果表明,聯(lián)網(wǎng)狀態(tài)下,通過AC/DC變換器平衡功率差額,能夠保證母線電壓維持在額定值；孤島狀態(tài)下,下垂控制可以使母線電壓維持在合理范圍,但會產(chǎn)生電壓偏差。 然后,分析了下垂控制導致母線電壓偏差的原因,在此基礎上,給出了母線電壓恢復控制策略,其實質是控制蓄電池充放電功率,以準確匹配光伏電源輸出功率與負載需求之間的功率差額。仿真結果表明,采用電壓恢復控制策略,即使光照強度和負載大小發(fā)生變化,母線電壓也能維持在額定值：但當光伏電源和負載之間的功率差額超過蓄電池功率上限時,母線電壓恢復控制策略失效,母線電壓仍會產(chǎn)生偏差。 最后,在下垂控制和母線電壓恢復控制的基礎上,研究了直流微電網(wǎng)的組網(wǎng)運行控制策略,從而形成了直流微電網(wǎng)的分層控制結構�？紤]蓄電池功率限制的四種工況仿真結果表明,通過改變網(wǎng)間電流的大小和方向,可以實現(xiàn)能量在微電網(wǎng)之間的雙向流動,但同時會導致母線電壓的偏差,電壓偏差的大小只與網(wǎng)間電流大小有關,當蓄電池容量受限時,網(wǎng)間電流可能發(fā)生跳變,引起電壓偏差的改變。
[Abstract]:In the face of the double pressure of environmental pollution and energy shortage, the distributed generation technology of clean economy has been widely used. However, the grid operation of large-scale distributed power supply can not be neglected in the safe and reliable operation of large power grid. In order to prevent this disadvantage, the concept of microgrid emerges as the times require. With the new energy and the power market management, it has the characteristics of strong flexibility and good interactivity. According to the nature of the bus current in the microgrid, the micro grid can be divided into three types of DC micro grid, AC microgrid and AC and DC hybrid microgrid. Compared with the latter two, the DC micro grid has high efficiency, low loss and strong controllability. But the DC micro grid is weak because of its limited capacity and weak anti disturbance ability. When the operating conditions change, it will easily cause the fluctuation of DC bus voltage and the reduction of power quality. Therefore, a suitable energy management and control strategy should be designed to maintain the voltage stability of the bus and manage the power quality of the microgrid. The paper is based on the modeling of the distributed power supply. The control model of DC microgrid is established, and the hierarchical energy management control strategy of DC microgrid is studied.
First, the working principle of photovoltaic power supply is expounded, and the practical model of the photovoltaic power supply is set up. On this basis, the maximum power tracking of the output of the photovoltaic power is carried out by the mountain climbing method. The simulation results show that the maximum power output can be realized even if the light intensity and the ambient temperature change, and the maximum power is verified. The efficiency of the rate tracking algorithm is presented. The charge discharge action principle of the battery is analyzed and a complete battery charging and discharging model is set up. The simulation results show that the model can switch charge and discharge according to the SOC state of the battery, and can reflect the physical characteristics of the battery well. The working principle of the bidirectional AC/DC converter is introduced and the design is introduced. In order to understand the coupling control model, it can be seen from the simulation results that the bidirectional flow of energy can be realized by controlling the switching between the two working states of the rectifier and the inverter.
Secondly, according to the working characteristics of the DC microgrid in different operating modes, based on the size of the bus voltage, the control strategy is designed for the photovoltaic power, the battery, the bidirectional AC/DC converter, and the load of the photovoltaic power is controlled in two operating states of the maximum power tracking output and the constant voltage mode; and the battery is designed. The droop control strategy adjusts the charge and discharge power of the battery according to the voltage of the bus. By switching the working state of the bidirectional AC/DC converter, the energy is achieved in the two-way flow between the microgrid and the large power grid. Under the heavy load of the system, the load strategy is used to restore the voltage of the bus to the normal range. The simulation results show that the combined power of the bus is restored to the normal range. In the network state, the balance of the power difference between the AC/DC converter can ensure that the bus voltage is maintained at the rated value. Under the island state, the droop control can keep the bus voltage in a reasonable range, but the voltage deviation will be produced.
Then, the cause of the bus voltage deviation caused by droop control is analyzed. On this basis, the control strategy of the bus voltage recovery is given. The essence is to control the charge and discharge power of the battery to accurately match the power difference between the output power of the photovoltaic power supply and the load demand. The simulation results show that the voltage recovery control strategy is adopted, even if the light is illuminated. The strength and load size change, the bus voltage can also be maintained at the rated value: but when the power difference between the photovoltaic power and the load is higher than the upper limit of the battery power, the bus voltage recovery control strategy is invalid and the bus voltage will still have a deviation.
Finally, on the basis of droop control and bus voltage recovery control, the control strategy of network operation of DC micro grid is studied, and the hierarchical control structure of DC microgrid is formed. The simulation results of four operating conditions considering the power limit of the battery show that the energy can be realized by changing the size and direction of the current between the network. The two-way flow between the networks, but at the same time leads to the bias of the bus voltage. The size of the voltage deviation is only related to the size of the Internet current. When the capacity of the battery is limited, the current between the networks may jump and cause the change of the voltage deviation.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM727

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相關期刊論文 前10條

1 唐西勝;齊智平;;獨立光伏系統(tǒng)中超級電容器蓄電池有源混合儲能方案的研究[J];電工電能新技術;2006年03期

2 吳衛(wèi)民;何遠彬;耿攀;錢照明;汪i襠，

本文編號：2112445