【摘要】：微網(wǎng)是以電力電子變換器為主體,配合以儲能和負荷單元,以控制策略為支撐,可實現(xiàn)多發(fā)電單元聯(lián)合供能、多控制策略協(xié)同工作、多層架構(gòu)靈活配合。本文主要工作是針對微網(wǎng)變換器間的協(xié)調(diào)控制及微網(wǎng)控制展開研究,主要分為以下幾個部分。首先,分析了 VSG控制與下垂控制之間的關(guān)系,推導了不同容量的多臺VSG之間的有功和無功功率的均分公式,對孤島模式下包含多臺VSG的微網(wǎng)進行分層控制,在第一層控制輸出特性穩(wěn)定的前提下,采用集中式控制,在第二層控制器中引入了對微網(wǎng)交流母線的頻率和電壓的二次補償控制。其次,分析了轉(zhuǎn)子運動方程中的轉(zhuǎn)動慣量對有功功率和頻率輸出特性的影響,在轉(zhuǎn)動慣量自適應(yīng)控制的基礎(chǔ)上,基于分層理念,研究了隸屬于二層控制的改進型轉(zhuǎn)動慣量自適應(yīng)控制。從VSG并聯(lián)穩(wěn)定性分析的角度給出了 VSG參數(shù)的大致取值范圍,并設(shè)計了頻率跟蹤系數(shù)的取值原則。仿真和實驗驗證了此種改進型轉(zhuǎn)動慣量自適應(yīng)控制可在時間尺度上通過自適應(yīng)地調(diào)節(jié)轉(zhuǎn)動慣量達到不同工況下的良好控制效果。再次,電網(wǎng)電壓不對稱情況下,依據(jù)具有調(diào)節(jié)系數(shù)的連續(xù)性電流給定算法,推導了有功和無功功率振蕩幅值以及電流峰值表達式,通過調(diào)節(jié)權(quán)重系數(shù)可實現(xiàn)特定的控制目標。針對不能同時抑制有功和無功功率振蕩,且電流峰值變大的問題,采取折中控制方式:有功功率在微網(wǎng)允許小幅范圍內(nèi)振蕩的前提下,通過多目標優(yōu)化算法使無功功率振蕩幅值和電流峰值最小,間接實現(xiàn)三種控制目標。最后,電網(wǎng)電壓不對稱情況下,針對含多臺變換器的交流微網(wǎng)的輸出有功功率的振蕩會引發(fā)前級直流微網(wǎng)中直流母線電壓的波動以及并網(wǎng)電流的電能質(zhì)量問題,以兩臺變換器并聯(lián)為例,研究了一種抑制有功功率振蕩的控制策略,通過實驗結(jié)果可知,所得權(quán)重系數(shù)可使保證微網(wǎng)總的有功功率在穩(wěn)態(tài)過程中以及在限制電流峰值的兩級調(diào)節(jié)過程中不振蕩,且總的無功功率振蕩幅值保持不變。
[Abstract]:Microgrid is based on power electronic converter, combined with energy storage and load unit, supported by control strategy, which can realize the joint energy supply of multiple power generation units, the cooperative work of multiple control strategies, and the flexible cooperation of multi-layer architecture. The main work of this paper is to study the coordinated control and microgrid control between microgrid converters, which is mainly divided into the following parts. Firstly, the relationship between VSG control and drooping control is analyzed, and the equal distribution formula of active power and reactive power between multiple VSG with different capacity is derived. the microgrid containing multiple VSG in isolated island mode is controlled layered. Under the premise that the output characteristics of the first layer control are stable, the centralized control is adopted, and the secondary compensation control of the frequency and voltage of the AC bus of the microgrid is introduced into the second layer controller. Secondly, the influence of moment of inertia on active power and frequency output characteristics in rotor motion equation is analyzed. on the basis of adaptive control of moment of inertia and hierarchical concept, the improved adaptive control of moment of inertia belonging to two-layer control is studied. From the point of view of VSG parallel stability analysis, the approximate range of VSG parameters is given, and the principle of frequency tracking coefficient is designed. The simulation and experimental results show that the improved adaptive control of moment of inertia can achieve good control effect under different working conditions by adaptively adjusting the moment of inertia on the time scale. Thirdly, under the condition of asymmetrical voltage of power grid, according to the continuous current given algorithm with regulation coefficient, the expressions of active and reactive power oscillation amplitude and current peak value are derived, and the specific control objectives can be achieved by adjusting the weight coefficient. In order to solve the problem that both active power and reactive power oscillations can not be suppressed at the same time, and the peak current becomes larger, a compromise control method is adopted: under the premise that active power oscillates in a small range allowed by microgrid, the amplitude and current peaks of reactive power oscillations are minimized by multi-objective optimization algorithm, and three control objectives are realized indirectly. Finally, under the condition of asymmetrical voltage of power grid, the fluctuation of DC bus voltage and the power quality of grid-connected current in the front DC microgrid will be caused by the output active power oscillation of AC microgrid with multiple converters. Taking the parallel connection of the two converters as an example, a control strategy to suppress the active power oscillation is studied. The obtained weight coefficient can ensure that the total active power of the microgrid does not oscillate in the steady state process and in the two-stage adjustment process of limiting the peak current, and the amplitude of the total reactive power oscillation remains unchanged.
【學位授予單位】：西安理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM46

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