本文選題：弱電網(wǎng) + 光伏逆變系統(tǒng)��； 參考：《華北電力大學》2014年博士論文

【摘要】：隨著化石能源的枯竭及其造成的環(huán)境危害日趨嚴重,各種方式的可再生能源發(fā)電快速增長。太陽能資源豐富,可多方式開發(fā)利用,光伏發(fā)電是現(xiàn)今的主要可再生能源發(fā)電方式之一。光伏發(fā)電聯(lián)網(wǎng)運行是實現(xiàn)太陽能大規(guī)模開發(fā)利用的重要途徑。但由于受資源稟賦的約束,大規(guī)模光伏電站多位于電網(wǎng)結(jié)構(gòu)薄弱地區(qū)。在光伏發(fā)展初期,光伏聯(lián)網(wǎng)規(guī)模與接入電網(wǎng)容量相比很小,可不考慮電網(wǎng)約束對光伏發(fā)電系統(tǒng)運行的影響；但隨著光伏電站容量的增大,所接入電網(wǎng)將呈現(xiàn)弱電網(wǎng)特征。 光伏發(fā)電通常經(jīng)逆變系統(tǒng)接入電網(wǎng),即光伏逆變系統(tǒng)。逆變器不僅將光伏電池產(chǎn)生的直流變換為交流送入電網(wǎng),還承擔著調(diào)控光伏電池運行狀態(tài)以實現(xiàn)最大功率跟蹤的任務。在電網(wǎng)結(jié)構(gòu)相對較強時,常規(guī)設計的光伏逆變系統(tǒng)具有較好的運行控制性能；當較大容量的光伏逆變系統(tǒng)接入弱電網(wǎng)時,光伏逆變系統(tǒng)的控制性能將會惡化,甚至存在系統(tǒng)運行失穩(wěn)的風險。在光伏入網(wǎng)規(guī)�？焖侔l(fā)展的背景下,評估弱電網(wǎng)對光伏逆變系統(tǒng)運行性能的影響,研究相應的改進措施以提高光伏逆變系統(tǒng)接入弱電網(wǎng)的運行品質(zhì)和安全性,具有重要的理論意義和現(xiàn)實意義。 本文以單級式三相聯(lián)網(wǎng)光伏逆變系統(tǒng)為研究對象,建立了包括光伏陣列,含(?)L濾波器逆變器的光伏逆變系統(tǒng)基礎數(shù)學模型,分析了光伏陣列的輸出特性.給出了主電路參數(shù)的設計方法,構(gòu)建了MPPT控制與逆變器功率控制結(jié)合的不閉環(huán)控制系統(tǒng)結(jié)構(gòu),并基于PSCAD/EMTDC平臺搭建了聯(lián)網(wǎng)光伏逆變仿真系統(tǒng),為光伏逆變系統(tǒng)接入弱電網(wǎng)運行分析與控制研究提供有效的工具。 在分析光伏逆變系統(tǒng)接入電網(wǎng)現(xiàn)實場景的基礎上,給出了描述電網(wǎng)強弱的指標,并基于此指標給出了弱電網(wǎng)的定義；建立了光伏逆變系統(tǒng)接入弱電網(wǎng)運行可行域的概念,光伏逆變系統(tǒng)接入弱電網(wǎng)運行約束的邊界可以用相應的電網(wǎng)阻抗際幺值來定量描述,即穩(wěn)定域由滿足控制器穩(wěn)定裕量約束和滿足接入點電壓調(diào)節(jié)品質(zhì)約束圍成。提出了可行域邊界的計算方法。 針對運行可行域的控制器穩(wěn)定裕量約束邊界,分析了弱電網(wǎng)對控制器穩(wěn)定裕量的不利影響,提出了取消電壓前饋的控制器結(jié)構(gòu)改進方案,以拓展光伏逆變系統(tǒng)接入弱電網(wǎng)運行的可行域,在結(jié)構(gòu)優(yōu)化的基礎上構(gòu)建了控制器參數(shù)優(yōu)化設計方法。 針對運行可行域的接入點電壓調(diào)節(jié)約束,分析了弱電網(wǎng)引起的功率傳輸瓶頸,比較了不同無功控制方式對運行可行域的影響。提出了一種面向接入點電壓調(diào)節(jié)的無功控制策略,以改善光伏逆變系統(tǒng)接入弱電網(wǎng)的電壓調(diào)節(jié)品質(zhì),并規(guī)避光伏逆變系統(tǒng)接入弱電網(wǎng)運行中潛在的電壓失穩(wěn)風險。
[Abstract]:With the depletion of fossil energy and the environmental hazards caused by fossil energy, renewable energy generation is increasing rapidly. Solar energy is rich in resources and can be exploited in many ways. Photovoltaic power generation is one of the main renewable energy generation methods. Photovoltaic network operation is an important way to realize large-scale development and utilization of solar energy. However, due to the constraints of resource endowment, large-scale photovoltaic power plants are located in weak areas of power grid structure. In the early stage of photovoltaic development, the scale of photovoltaic network is very small compared with the capacity of access grid, and the influence of grid constraints on the operation of photovoltaic power system can be ignored, but with the increase of the capacity of photovoltaic power station, the connected grid will show the characteristics of weak grid. Photovoltaic power generation is usually connected to the power grid through the inverter system, that is, the photovoltaic inverter system. The inverter not only converts the DC generated by photovoltaic cells into AC into the power grid, but also takes on the task of regulating the operating state of photovoltaic cells to achieve maximum power tracking. When the grid structure is relatively strong, the conventional photovoltaic inverter system has better control performance, and the control performance of the photovoltaic inverter system will deteriorate when the larger PV inverter system is connected to the weak grid. There is even the risk of system instability. Under the background of the rapid development of photovoltaic network, the influence of weak grid on the performance of PV inverter system is evaluated, and the corresponding improvement measures are studied to improve the operation quality and security of PV inverter system connected to weak grid. It has important theoretical and practical significance. In this paper, the basic mathematical model of photovoltaic inverter system including photovoltaic array and inverter is established, and the output characteristics of photovoltaic array are analyzed. The design method of the main circuit parameters is given, and the structure of the non-closed loop control system which combines MPPT control and inverter power control is constructed. Based on the PSCAD / EMTDC platform, a networked photovoltaic inverter simulation system is built. It provides an effective tool for the research of operation analysis and control of PV inverter system connected to weak power grid. On the basis of analyzing the reality scene of PV inverter system connecting to power grid, this paper gives the index to describe the power grid strength, and gives the definition of weak current network based on this index, and establishes the concept of feasible region for PV inverter system to connect to weak grid operation. The boundary of access to weak grid operation constraints for PV inverters can be quantitatively described by the corresponding interimpedance unitary values, i.e., the stability region is surrounded by satisfying the controller stability margin constraints and satisfying the access point voltage regulation quality constraints. A method for calculating the boundary of feasible region is presented. Aiming at the stability margin constraint boundary of the controller in the operational feasible region, this paper analyzes the adverse effect of the weak current network on the stability margin of the controller, and puts forward a scheme to improve the structure of the controller by eliminating the voltage feedforward. In order to extend the feasible region of the PV inverter system connecting to the weak power grid, the optimal design method of controller parameters is constructed on the basis of structural optimization. Aiming at the voltage regulation constraints of the access point in the operational feasible region, the bottleneck of power transmission caused by the weak current network is analyzed, and the influence of different reactive power control modes on the operational feasible region is compared. A reactive power control strategy for access point voltage regulation is proposed to improve the voltage regulation quality of the PV inverter system connected to the weak grid and to avoid the potential voltage instability risk during the access of the PV inverter system to the weak grid.
【學位授予單位】：華北電力大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM615

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