本文選題：電網(wǎng)阻抗　切入點：小信號模型　出處：《中國礦業(yè)大學》2017年碩士論文

【摘要】：并網(wǎng)逆變器作為分布式發(fā)電系統(tǒng)的核心部分,電網(wǎng)阻抗對逆變器穩(wěn)定性的影響不可忽略。電網(wǎng)阻抗攝動會導致LCL濾波器諧振頻率出現(xiàn)大范圍波動,進而導致系統(tǒng)出現(xiàn)振蕩;電網(wǎng)阻抗會影響公共耦合點電壓,導致鎖相環(huán)輸出不穩(wěn)定,影響并網(wǎng)質(zhì)量。本文通過建立并網(wǎng)逆變器的小信號模型,分析在傳統(tǒng)PI控制策略下,單電流閉環(huán)和包含電容電流反饋的電流閉環(huán)兩種不同控制結(jié)構(gòu)對電網(wǎng)阻抗攝動的抑制能力。單電流閉環(huán)對電網(wǎng)阻抗攝動容許范圍小;包含電容電流反饋電流閉環(huán)存在固有不穩(wěn)定頻率范圍,當諧振頻率處于該范圍時控制器始終無法保證系統(tǒng)穩(wěn)定。此外本文分析了電網(wǎng)阻抗攝動對鎖相環(huán)輸出的影響。本文對電網(wǎng)阻抗攝動情況下并網(wǎng)逆變器控制提出采用H_∞魯棒控制策略,通過建立包含電網(wǎng)阻抗不確定性的數(shù)學模型,合理選擇加權(quán)函數(shù),得到七階H_∞魯棒控制器。由于七階控制器需要更多計算量和存儲器,對七階控制器進行降階得到三階控制器,該三階控制器可以保留原控制器良好的系統(tǒng)跟蹤性能和魯棒性能。針對電網(wǎng)阻抗攝動導致鎖相環(huán)輸出不穩(wěn)定的問題,本文采用基于復數(shù)濾波器的鎖相環(huán),有效抑制了電網(wǎng)阻抗對鎖相環(huán)的干擾。本文對基于傳統(tǒng)PI控制和H_∞魯棒控制的LCL濾波并網(wǎng)逆變器系統(tǒng)進行了仿真,并且搭建了實驗平臺,仿真和實驗通過對比兩種不同控制策略,證明了本文設(shè)計的H_∞魯棒控制器的優(yōu)越性。
[Abstract]:Grid-connected inverter is the core part of distributed generation system. The influence of grid impedance on inverter stability can not be ignored. Power grid impedance perturbation will cause the resonance frequency of LCL filter to fluctuate in a wide range, and then lead to the oscillation of the system. Power grid impedance will affect common coupling point voltage, lead to unstable output of PLL and affect grid-connected quality. In this paper, a small-signal model of grid-connected inverter is established, and the conventional Pi control strategy is analyzed. The single current closed loop and the current closed loop with capacitive current feedback can restrain the impedance perturbation of the power network, and the single current closed loop has a small allowable range for the impedance perturbation of the power network. Contains the inherent unstable frequency range of the current closed-loop with capacitive current feedback, When the resonant frequency is in this range, the controller can not guarantee the stability of the system. In addition, the influence of impedance perturbation on the output of PLL is analyzed. The control of grid-connected inverter under the condition of grid impedance perturbation is proposed in this paper. Using H _ 鈭，

本文編號：1692283