本文選題：交流微電網(wǎng) + 下垂控制　； 參考：《浙江大學(xué)》2014年博士論文

【摘要】：全球性的能源危機(jī)與環(huán)境危機(jī)迫使世界各國尋找傳統(tǒng)化石能源發(fā)電的替代品。近年來可再生能源發(fā)電技術(shù)逐漸興起,其合理利用可以作為現(xiàn)有化石能源發(fā)電形式的有益補(bǔ)充,并最終成為解決能源危機(jī)的有效途徑。微電網(wǎng)可以將各種類型的可再生能源發(fā)電單元以及儲(chǔ)能元件有機(jī)集成為一個(gè)系統(tǒng),為用戶提供穩(wěn)定、可靠、優(yōu)質(zhì)的電能。在微電網(wǎng)系統(tǒng)中,穩(wěn)定運(yùn)行是首要的,因而微電網(wǎng)的小信號(hào)穩(wěn)定性問題是學(xué)術(shù)界的研究重點(diǎn)之一。論文在總結(jié)現(xiàn)有的交流微電網(wǎng)系統(tǒng)小信號(hào)穩(wěn)定性分析方法的基礎(chǔ)上,提出了基于元件等效阻抗模型的系統(tǒng)小信號(hào)穩(wěn)定性分析方法,并將該方法應(yīng)用于單母線微電網(wǎng)和網(wǎng)狀網(wǎng)絡(luò)拓?fù)浣Y(jié)構(gòu)微電網(wǎng)的小信號(hào)穩(wěn)定性分析。同時(shí),提出了通過控制輸出阻抗的方式抑制孤島微電網(wǎng)帶非線性負(fù)載時(shí)的電壓諧波,并通過電網(wǎng)電壓與頻率前饋的方式穩(wěn)定并網(wǎng)潮流。 首先,論文推導(dǎo)了基于下垂控制電壓型變流器(Power Conditioning System, PCS)、負(fù)載及線路阻抗、電網(wǎng)等在d-q同步旋轉(zhuǎn)坐標(biāo)系下的等效模型,分別為戴維南等效模型、阻抗模型、電壓源模型等。以此為基礎(chǔ),建立了三相交流微電網(wǎng)在d-q坐標(biāo)系下的網(wǎng)絡(luò)等效模型,并推導(dǎo)出系統(tǒng)中各元件功率閉環(huán)特征方程,根據(jù)功率閉環(huán)特征方程即可求解出某一特定參數(shù)下系統(tǒng)各元件功率閉環(huán)特征根,特征根的分布即可用來預(yù)測(cè)系統(tǒng)的動(dòng)態(tài)特性與小信號(hào)穩(wěn)定性。進(jìn)一步地,設(shè)置某些參數(shù)變化,即可求解出系統(tǒng)閉環(huán)特征根隨該參數(shù)變化的根軌跡,從而可以利用這一方法來判斷各個(gè)控制參數(shù)對(duì)系統(tǒng)的動(dòng)態(tài)特性與穩(wěn)定性的影響,并據(jù)此設(shè)計(jì)出恰當(dāng)?shù)目刂茀?shù)�；谠撍枷�,論文以單母線微電網(wǎng)為例,推導(dǎo)了并網(wǎng)及孤島模式下的微電網(wǎng)模型,并求解出功率閉環(huán)特征方程隨某些控制參數(shù)變化的根軌跡。 其次,論文所提出的微電網(wǎng)建模方法是先給出系統(tǒng)的在d-q同步旋轉(zhuǎn)坐標(biāo)系下的等效電路模型,然后利用基本電路方程導(dǎo)出系統(tǒng)閉環(huán)功率特征方程,且系統(tǒng)描述方程的矩陣規(guī)模與網(wǎng)絡(luò)拓?fù)浣Y(jié)構(gòu)無關(guān),只與組網(wǎng)PCS數(shù)量相關(guān),因而特別適用于求解網(wǎng)絡(luò)結(jié)構(gòu)比較復(fù)雜的系統(tǒng)。而在目前的文獻(xiàn)檢索范圍內(nèi),并無系統(tǒng)地討論網(wǎng)狀拓?fù)浣Y(jié)構(gòu)微電網(wǎng)的相關(guān)工作�；诖�,論文提出了一種交流微電網(wǎng)系統(tǒng)的一般化網(wǎng)狀網(wǎng)絡(luò)拓?fù)浣Y(jié)構(gòu),并利用論文提出的建模方法推導(dǎo)出該系統(tǒng)中各元件的功率閉環(huán)特征方程以及根軌跡,從而可以預(yù)測(cè)系統(tǒng)的動(dòng)態(tài)特性及小信號(hào)穩(wěn)定性。此外,論文還給出了該通用微電網(wǎng)拓?fù)浣Y(jié)構(gòu)演變?yōu)槠渌負(fù)浣Y(jié)構(gòu)的一般方法。 再者,論文推導(dǎo)了下垂控制電壓型PCs的輸出阻抗模型,并分析了逆變器輸出阻抗對(duì)電壓波形的影響。孤島運(yùn)行時(shí),若微電網(wǎng)存在非線性負(fù)荷,諧波電流會(huì)在逆變器的輸出阻抗上產(chǎn)生諧波壓降,進(jìn)而導(dǎo)致輸出電壓波形畸變,從而嚴(yán)重影響微電網(wǎng)的電壓波形質(zhì)量。論文提出通過控制逆變器輸出阻抗的方法,改善微電網(wǎng)孤島運(yùn)行時(shí)的電壓波形質(zhì)量。此外,下垂控制逆變器并網(wǎng)運(yùn)行時(shí),并網(wǎng)潮流受電網(wǎng)電壓與頻率隨機(jī)波動(dòng)的影響,也會(huì)存在隨機(jī)波動(dòng),影響并網(wǎng)潮流控制的精確性。論文提出通過電網(wǎng)電壓與頻率前饋的方法抑制電網(wǎng)波動(dòng)對(duì)并網(wǎng)潮流影響。 論文所提出的微電網(wǎng)建模方法,能夠很好地應(yīng)用于求解并網(wǎng)運(yùn)行或孤島運(yùn)行的三相交流微電網(wǎng),且該方法適用于求解網(wǎng)絡(luò)結(jié)構(gòu)較為復(fù)雜的微電網(wǎng)系統(tǒng)。推導(dǎo)系統(tǒng)閉環(huán)功率特征方程與求取根軌跡,為微電網(wǎng)中PCS的控制參數(shù)設(shè)計(jì)、微電網(wǎng)小信號(hào)穩(wěn)定性問題的分析提供了新思路。 最后,論文介紹了基于RT-LAB的三相交流微電網(wǎng)實(shí)驗(yàn)平臺(tái)的研發(fā)。該系統(tǒng)包含三臺(tái)電壓型逆變器,以RT-LAB作為虛擬控制器,可以用于驗(yàn)證論文所推導(dǎo)的微電網(wǎng)小信號(hào)模型,以及微電網(wǎng)電壓波形質(zhì)量問題。同時(shí),由于該實(shí)驗(yàn)平臺(tái)的通用性,也可以用于其它不同網(wǎng)絡(luò)形態(tài)和負(fù)載條件的微電網(wǎng)實(shí)驗(yàn)研究,加快科研進(jìn)度。
[Abstract]:The global energy crisis and environmental crisis have forced the countries all over the world to look for the alternative to traditional fossil energy generation. In recent years, the renewable energy generation technology has gradually emerged. Its rational use can be a useful supplement to the existing fossil energy generation form, and eventually become an effective way to solve the energy crisis. The type of renewable energy generating unit and energy storage element are integrated into a system to provide users with stable, reliable and high quality electric energy. The stability of the microgrid is the first priority in the microgrid system, so the problem of the small signal stability of the microgrid is one of the key points in the academic field. On the basis of the number stability analysis method, a system small signal stability analysis method based on the component equivalent impedance model is proposed, and the method is applied to the small signal stability analysis of the single bus microgrid and the mesh network topology microgrid. At the same time, the control output impedance is proposed to suppress the islanding microgrid zone. The voltage harmonics in linear load are stabilized by grid voltage and frequency feedforward.
First, the paper derives the equivalent model based on Power Conditioning System (PCS), load and line impedance, power grid and so on in d-q synchronous rotating coordinate system, which are the equivalent model, impedance model and voltage source model, respectively. Based on this, the three-phase AC microgrid is established in the d-q coordinate system. The network equivalent model is used to derive the closed loop characteristic equation of each component in the system. According to the power closed-loop characteristic equation, the closed-loop characteristic root of each component of the system can be solved. The distribution of the characteristic root can be used to predict the dynamic characteristics of the system and the stability of the small signal. This method can be used to determine the influence of the control parameters on the dynamic characteristics and stability of the system, and the appropriate control parameters are designed based on this method. Based on this idea, a single bus micro electric network is taken as an example to deduce the micro electricity under the mode of grid and Isle. The root locus of the power closed loop characteristic equation with certain control parameters is solved.
Secondly, the method of modeling microgrid proposed in this paper first gives the equivalent circuit model of the system in d-q synchronous rotating coordinate system, and then uses the basic circuit equation to derive the closed loop power characteristic equation of the system, and the matrix scale of the system description equation is independent of the network topology, and is only related to the number of network PCS, so it is especially suitable for the system. In the context of current literature retrieval, there is no systematic discussion of the related work of network topology microgrid. Based on this, a general network topology of the AC microgrid system is proposed, and the components in the system are derived from the modeling method proposed in this paper. The power closed-loop characteristic equation and the root locus can be used to predict the dynamic characteristics of the system and the stability of the small signal. In addition, the general method of the evolution of the general microgrid topology into other topological structures is also given.
Furthermore, the output impedance model of the droop controlled voltage type PCs is derived, and the influence of the output impedance of the inverter on the voltage waveform is analyzed. If there is a nonlinear load in the isolated island, the harmonic current will produce the harmonic voltage drop on the output impedance of the inverter, which leads to the distortion of the output voltage waveform, thus seriously affecting the micropower. By controlling the output impedance of the inverter, the paper puts forward the method of controlling the output impedance of the inverter to improve the quality of the voltage waveform of the microgrid. In addition, when the droop control inverter is connected to the grid, the grid flow is affected by the random fluctuation of the voltage and frequency of the power grid, and it will also exist in the random fluctuation, which affects the accuracy of the grid power flow control. In this paper, a feed-forward method of grid voltage and frequency is proposed to suppress the influence of grid fluctuation on grid connected power flow.
The method of micro grid modeling proposed in this paper can be used to solve the three-phase AC microgrid with grid connected operation or island operation, and this method is suitable for solving the complex network structure of the network structure. The closed-loop power characteristic equation and the root locus are derived, and the PCS control parameters in the microgrid are designed and the micro grid is small. The analysis of the problem of signal stability provides a new way of thinking.
Finally, the paper introduces the research and development of a three-phase AC microgrid experiment platform based on RT-LAB. The system includes three voltage inverters and RT-LAB as a virtual controller. It can be used to verify the microgrid small signal model derived from the paper and the quality of the voltage waveform of the microgrid. In order to speed up the progress of scientific research, microgrid experiments are carried out for other network configurations and load conditions.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM712

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本文編號(hào)：1933641