本文選題：并網(wǎng)逆變器 + LCL濾波器��； 參考：《華中科技大學(xué)》2014年碩士論文

【摘要】：傳統(tǒng)化石能源的開發(fā)利用導(dǎo)致能源危機和環(huán)境污染問題，以太陽能、風(fēng)能為代表的分布式并網(wǎng)發(fā)電越來越受到重視。LCL型并網(wǎng)逆變器是連接分布式源和電網(wǎng)的接口裝置之一。為保證其穩(wěn)定工作，，通常采用電容電流反饋有源阻尼來抑制LCL濾波器的諧振峰。采用數(shù)字控制時，控制延時會導(dǎo)致系統(tǒng)穩(wěn)定約束條件復(fù)雜且對電網(wǎng)阻抗的魯棒性差。本文針對數(shù)字控制電容電流反饋有源阻尼的LCL型并網(wǎng)逆變器，分析考慮電網(wǎng)阻抗的控制參數(shù)設(shè)計方法，以提高并網(wǎng)逆變器對電網(wǎng)阻抗魯棒性。 本文首先建立數(shù)字控制時電容電流反饋有源阻尼LCL型并網(wǎng)逆變器的數(shù)學(xué)模型。通過控制框圖的等效變換，分析控制延時對阻尼效果的影響，并討論系統(tǒng)的穩(wěn)定約束條件。在此基礎(chǔ)上，進一步考慮電網(wǎng)阻抗的變化，給出阻抗交截和極點軌跡圖兩種判斷系統(tǒng)穩(wěn)定性的方法。 通過分析電網(wǎng)阻抗與系統(tǒng)穩(wěn)定約束條件之間的關(guān)系，本文推導(dǎo)出并網(wǎng)逆變器不穩(wěn)定的電網(wǎng)阻抗值域，并提出一種提高系統(tǒng)對電網(wǎng)阻抗魯棒性的控制參數(shù)設(shè)計方法。采用該方法設(shè)計的控制參數(shù)，如果電網(wǎng)阻抗變化時LCL濾波器的諧振頻率不跨越1/6采樣頻率，則電網(wǎng)阻抗變化時LCL型并網(wǎng)逆變器系統(tǒng)恒穩(wěn)定；如果電網(wǎng)阻抗變化時諧振頻率跨越1/6采樣頻率，則除一臨界點外系統(tǒng)恒穩(wěn)定。 針對電容電流滯后一拍反饋存在的穩(wěn)定性問題，本文討論電容電流即時反饋在提高并網(wǎng)逆變器穩(wěn)定性方面的效果，并對這兩種電容電流反饋有源阻尼方式的等效物理模型和對電網(wǎng)阻抗的魯棒性進行分析。 以單相LCL型并網(wǎng)逆變器為例，在實驗室研制一臺6kW的原理樣機，并完成相關(guān)的實驗研究，實驗結(jié)果驗證了理論分析的正確性。
[Abstract]:The development and utilization of traditional fossil energy lead to energy crisis and environmental pollution. Distributed grid-connected power generation, represented by solar and wind energy, is paid more and more attention to. LCL grid-connected inverter is one of the interface devices to connect distributed source and power grid. In order to ensure its stable operation, the capacitive current feedback active damping is usually used to suppress the resonant peak of LCL filter. When digital control is adopted, the control delay will lead to complex system stability constraints and poor robustness to grid impedance. In order to improve the robustness of grid-connected inverters to grid-connected inverters based on digital control capacitive current-feedback active damping LCL grid-connected inverter, the design method of control parameters considering grid impedance is analyzed in order to improve the robustness of grid-connected inverters to grid impedance. In this paper, the mathematical model of capacitive current feedback active damping LCL grid-connected inverter is established. Through the equivalent transformation of the control block diagram, the influence of control delay on damping effect is analyzed, and the stability constraints of the system are discussed. On the basis of this, two methods to judge the stability of the system are given, which are the impedance intersecting and the pole trajectory diagram, considering further the variation of the impedance of the power system. Based on the analysis of the relationship between power impedance and system stability constraints, the unsteady range of grid impedance of grid-connected inverters is derived, and a control parameter design method to improve the robustness of the system to power impedance is proposed. If the resonant frequency of the LCL filter does not exceed 1 / 6 sampling frequency when the power impedance changes, the LCL grid-connected inverter system will be stable when the power impedance changes. If the resonant frequency exceeds 1 / 6 sampling frequency when the impedance of the power system changes, the system is stable except for a critical point. Aiming at the stability problem of capacitor current lag beat feedback, this paper discusses the effect of capacitor current instant feedback on improving the stability of grid-connected inverter. The equivalent physical models of the two kinds of capacitive current feedback active damping methods and their robustness to the grid impedance are analyzed. Taking single-phase LCL grid-connected inverter as an example, a prototype of 6kW is developed in the laboratory. The experimental results verify the correctness of the theoretical analysis.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM464

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