本文選題：風力發(fā)電 + 雙饋感應發(fā)電機�。� 參考：《浙江大學》2014年博士論文

【摘要】：隨著風電在電網中所占比重的大幅增加,并網風電機組對電力系統(tǒng)的穩(wěn)定性影響日益顯著。為此,世界各主要風電大國紛紛出臺并網導則,對風電機組的運行可靠性作出明確要求。其中,并網導則對風電機組在電網故障條件下的行為約束,被公認為是對風電機組的嚴峻挑戰(zhàn)。該約束的核心要求可概括為,不僅要求風電機組能夠“適應”各類電網故障,還要求其具備“支撐”故障電網恢復的能力。從常見電網故障類型角度看,電網電壓不平衡、諧波畸變、對稱(或不對稱)驟升、跌落故障對并網風電機組的危害最為直接、普遍,影響也最為顯著。因此,開展該類電網故障下并網風電機組的運行特性研究,并提出相應控制對策,具有十分重要的理論研究和工程應用價值。 在此背景下,本文以作為主流機型的雙饋型風電機組為研究對象,以諧振控制器的拓展應用為核心,以理論分析、仿真研究和實驗驗證為手段,深入、系統(tǒng)研究了該類風電機組在電網電壓不平衡及諧波畸變、跌落及驟升等常見故障下的行為特征,提出了與并網導則相適應的電網友好型風電機組的改進控制策略。論文的研究重點是：1)廣義電網電壓不平衡及諧波畸變時DFIG機組的建模分析及諧振控制策略；2)電網驟升故障下DFIG機組的高電壓穿越運行技術。論文的主要研究內容和貢獻有： 1.系統(tǒng)梳理了諧振控制器在雙饋風電變流器應用中的關鍵問題,為該技術在風電場中的推廣應用奠定了理論基礎。內容包括：對比研究了三種諧振(R)控制器的常見應用形式,即比例諧振(PR)、矢量比例積分(VPI)和比例積分諧振(PIR)控制器,從對基波、諧波電流的調節(jié)能力、計算復雜性和頻率自適應能力三個方面歸納了三種控制器的基本特點和適用場合；以PR控制器為例,系統(tǒng)解答了R控制器在工程應用中需關注的三個難點問題,即參數(shù)整定、相位補償和離散化,特別地,提出了一種基于根軌跡法和頻域分析法相結合、較完整的基頻、多倍頻PR控制器參數(shù)設計方案；此外還提出了一種基于諧振控制器的電網電壓同步信號的檢測方法。 2.首次從電網不平衡及含低次電壓諧波時DFIG機組的數(shù)學建模入手,采用解析表達的形式評估了該類電網故障對DFIG定子(或轉子)電流不平衡度、畸變程度以及對瞬時有功、無功功率和電磁轉矩的影響；基于所建立的DFIG完整數(shù)學模型,提出了改善機組運行性能的諧振控制策略。首先建立了電網電壓含5次、7次等低次諧波分量時DFIG的完整數(shù)學模型,評估了低次諧波對DFIG定子瞬時有功、無功功率和電磁功率的影響；基于DFIG的建模分析,提出了相應可選控制目標及相應電流指令算法,提出了適應諧波電網工況的DFIG風電機組諧振電流控制方案。 3.將上述建模方法拓展應用到電網電壓不平衡且含5次、7次等低次諧波時的復雜電網工況,重構了該類工況下DFIG定子瞬時有功、無功功率和電磁功率的表達,厘清了功率、轉矩中各類波動成分產生的根由；并據此提出了電網不平衡且含低次諧波電壓時DFIG網側、轉子側變流器的協(xié)同控制方案；基于所建立的DFIG風電機組完整數(shù)學模型,從工程應用角度出發(fā),對DFIG轉子側、網側變流器的電流指令簡化和控制結構進行了系統(tǒng)改進、優(yōu)化,提高了控制策略的工程實用性；首次建立了廣義電網諧波條件下DFIG的一般化數(shù)學模型,該模型不僅可以用來分析5次、7次等傳統(tǒng)電壓諧波對DFIG運行性能的影響,也適用于分數(shù)次諧波甚至低頻振蕩危害的評估,具有較強的普適性,實現(xiàn)了本文數(shù)學建模思想的升華。 4.系統(tǒng)研究了電網電壓驟升、跌落故障發(fā)生時DFIG風電機組的暫態(tài)響應過程,并結合并網導則要求,提出了DFIG機組的高電壓穿越(HVRT)低電壓穿越(LVRT)協(xié)同控制和保護方案。內容包括：分析了電網電壓驟升故障對DFIG風電機組的主要危害,提出了影響DFIG機組HVRT運行能力的主要因素,據此提出了DFIG風電機組實現(xiàn)HVRT的可行性思路；從并網導對風電機組無功電流輸出要求的角度,提出了滿足DFIG機組HVRT運行的控制和保護策略；系統(tǒng)歸納了DFIG風電機組LVRT運行的技術難點和關鍵問題,在現(xiàn)有風電機組保護模塊基礎上,提出了完整的DFIG機組高、低電壓穿越協(xié)同控制和保護實施方案。 5.研制了一種新型可編程電網故障模擬電源,該電源能夠模擬電網電壓對稱、不對稱跌落,三相不平衡,電壓諧波畸變,頻率漂移,相角跳變,電壓幅值波動等多種電網故障,或兩至三種故障兼而有之,且故障嚴重程度、持續(xù)時間等參數(shù)均可編程調節(jié)。與此同時,研發(fā)了一套5.5kW雙饋風電機組樣機,驗證了本文所提出的電網電壓廣義不平衡及諧波畸變下DFIG機組數(shù)學模型的正確性、諧振控制策略的有效性,以及DFIG風電機組高電壓穿越、低電壓穿越協(xié)同控制方案的可靠性和穩(wěn)定性。
[Abstract]:With the large increase of the proportion of wind power in the power grid, the influence of grid connected wind turbines on the stability of the power system is becoming more and more significant. For this reason, the major power countries in the world have issued a grid guiding principle, making clear requirements for the reliability of the operation of the wind turbines. It is recognized as a severe challenge to the wind turbines. The core requirements of this constraint can be summarized as not only that the wind turbines are required to "adapt" to various types of power grid failures, but also to have the ability to "support" the restoration of the power grid. From the perspective of common grid fault types, the voltage imbalance, harmonic distortion, or asymmetry of the electric network, the harmonic distortion, or asymmetry. Rising and falling faults are the most direct and universal damage to the grid connected wind turbines. Therefore, it is of great importance for theoretical research and engineering application to carry out the research on the operating characteristics of the grid connected wind turbines under the fault of this kind of power grid and put forward the corresponding control countermeasures.
Under this background, this paper takes the doubly fed wind turbine as the main model, and takes the expansion and application of the resonant controller as the core, with the theoretical analysis, the simulation research and the experimental verification as the means, deeply and systematically, and systematically studies the common faults of this kind of wind turbine under the voltage imbalance of the power grid and the harmonic distortion, falling and rising. For the characteristics, an improved control strategy for the grid friendly wind turbine is proposed. The key points of this paper are as follows: 1) the modeling and analysis of DFIG unit and the resonant control strategy of the generalized grid voltage unbalance and harmonic distortion; 2) high voltage crossing operation technology under the sudden failure of the power grid. The research content and contribution are as follows:
1. the key problems in the application of the resonant controller in the doubly fed wind power converter are combed, which lays a theoretical foundation for the popularization and application of the technology in the wind farm. The contents include: comparison and study of the common applications of the three R controllers, namely, proportional resonance (PR), vector proportional integral (VPI) and proportional integral resonance (PIR) controller The basic characteristics and applicable situations of the three controllers are summed up from three aspects: the fundamental wave, the harmonic current adjustment ability, the computational complexity and the frequency adaptive ability. With the PR controller as an example, this paper systematically answers three difficult problems that the R controller needs to pay attention to in the engineering application, namely, the parameter setting, the phase compensation and the discretization, especially, Based on the combination of the root locus method and the frequency domain analysis method, a more complete parameter design scheme of the basic frequency and multiple frequency PR controller is proposed. In addition, a method of detecting the voltage synchronization signal of the power grid based on the resonant controller is also proposed.
2. for the first time, starting with the mathematical modeling of the DFIG unit with the unbalanced power grid and the low secondary voltage harmonics, the influence of the power grid fault on the current imbalance of the DFIG stator (or rotor), the degree of distortion, the instantaneous active power, the reactive power and the electromagnetic torque are evaluated by the analytical expression. Based on the complete mathematical model of the DFIG, a complete mathematical model is proposed. A resonant control strategy to improve the operating performance of the unit is given. First, a complete mathematical model of DFIG is established for the voltage of 5 and 7 second low harmonic components. The effect of low harmonic on the instantaneous active power, reactive power and electromagnetic power of the DFIG stator is evaluated. Based on the modeling and analysis of DFIG, the corresponding optional control targets and corresponding electricity are proposed. A current control algorithm for DFIG wind turbines adapting to harmonic power grid conditions is proposed.
3. the above modeling method is extended and applied to the complex network condition when the power grid voltage is unbalance and contains 5 times and 7 second low harmonic. The instantaneous active power, reactive power and electromagnetic power of the DFIG stator are reconstructed, and the root cause of all kinds of fluctuating components in the power and torque is clarified. The coordinated control scheme of the DFIG net side and the rotor side converter in the low harmonic voltage voltage is based on the complete mathematical model of the DFIG wind turbine. From the point of view of the engineering application, the current instruction simplification and control structure of the DFIG rotor side, the net side converter and the control structure are improved, and the engineering practicability of the control strategy is improved. The general mathematical model of DFIG under the condition of generalized grid harmonic is established. This model can not only be used to analyze the influence of the 5, 7 and other traditional voltage harmonics on the performance of the DFIG, but also to the assessment of the damage of fractional harmonic and even low frequency oscillation. It has a strong universality and realizes the sublimation of the mathematical modeling thought in this paper.
4. systematically studies the transient response process of the DFIG wind turbine when the power grid voltage rises suddenly and the falling fault occurs. Combined with the requirements of the grid guidance, the DFIG unit's high voltage crossing (HVRT) low voltage crossing (LVRT) cooperative control and protection scheme is proposed. The contents include the main damage to the DFIG wind turbine by the analysis of the voltage rising fault of the power grid. The main factors that affect the operation ability of the DFIG unit HVRT are put forward. According to this, the feasibility of the DFIG wind turbine to realize the HVRT is put forward. The control and protection strategy for the HVRT operation of the DFIG unit is put forward from the angle of the output requirement of the reactive current of the wind turbine, and the technical difficulty of the LVRT operation of the DFIG wind turbine is attributed to the system. And key problems, based on the existing wind turbine protection module, a complete implementation plan of DFIG unit's high voltage and low voltage ride through cooperative control and protection is put forward.
5. a new programmable power grid fault analog power supply is developed. The power supply can simulate the voltage symmetry, asymmetric drop, three-phase unbalance, voltage harmonic distortion, frequency drift, phase angle jump, voltage amplitude fluctuation and so on, or two to three kinds of faults, and the parameters of the fault severity, duration and so on At the same time, a prototype of 5.5kW doubly fed wind turbine is developed, which validates the correctness of the mathematical model of the DFIG unit under the generalized unbalance of voltage and the harmonic distortion, the validity of the resonant control strategy, the high voltage crossing of the DFIG wind turbine group and the reliability and stability of the co control scheme of low voltage crossing. Qualitative.

【學位授予單位】：浙江大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM614;TM46

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