LCL型并網(wǎng)逆變器數(shù)字電流控制技術(shù)研究
本文選題:并網(wǎng)逆變器 切入點(diǎn):延時(shí)補(bǔ)償 出處:《湘潭大學(xué)》2017年碩士論文
【摘要】:為了使新能源系統(tǒng)發(fā)出的電能穩(wěn)定、高效地并入電網(wǎng),性能效果優(yōu)良的高階濾波器已廣泛地應(yīng)用于新能源系統(tǒng)與電網(wǎng)之間的并網(wǎng)逆變器,但高階的LCL濾波器存在自身諧振問(wèn)題影響并網(wǎng)逆變器接口設(shè)備的性能,傳統(tǒng)的并網(wǎng)逆變器諧振抑制問(wèn)題多數(shù)在模擬域進(jìn)行研究與分析,但隨著數(shù)字信號(hào)處理技術(shù)和數(shù)字芯片的飛速發(fā)展,全數(shù)字控制逐漸取代模擬控制,數(shù)字控制中延時(shí)環(huán)節(jié)對(duì)系統(tǒng)穩(wěn)定性的影響已不可忽略,因此本文從考慮延時(shí)環(huán)節(jié)的并網(wǎng)逆變器離散數(shù)學(xué)建模、數(shù)字電流單環(huán)、雙環(huán)有源阻尼諧振抑制控制進(jìn)行了系統(tǒng)的分析和討論。采用直接數(shù)字法,分析并搭建了考慮數(shù)字延時(shí)環(huán)節(jié)的LCL型并網(wǎng)逆變器離散數(shù)學(xué)模型。在連續(xù)域和離散域下,對(duì)網(wǎng)側(cè)電流單環(huán)控制穩(wěn)定性進(jìn)行對(duì)比分析,說(shuō)明數(shù)字延時(shí)環(huán)節(jié)改變了系統(tǒng)穩(wěn)定性,基于此在網(wǎng)側(cè)電流單環(huán)反饋控制中設(shè)置數(shù)字延時(shí)為滯后一拍,主要分析滯后一拍情況下采樣頻率和諧振頻率之比對(duì)穩(wěn)定性的影響,并確定其穩(wěn)定范圍,同時(shí)對(duì)控制器參數(shù)進(jìn)行了設(shè)計(jì)。在較低諧振頻率和采樣頻率的比值下,網(wǎng)側(cè)電流數(shù)字單環(huán)控制難以保持穩(wěn)定,造成網(wǎng)側(cè)電流數(shù)字單環(huán)魯棒性不足,因此本文進(jìn)一步研究數(shù)字電容電流反饋有源阻尼方法增強(qiáng)阻尼,分析了數(shù)字電容電流反饋帶來(lái)的內(nèi)環(huán)數(shù)字延時(shí)對(duì)有源阻尼方法的影響,并針對(duì)其影響提出一種預(yù)測(cè)占空比結(jié)合零極點(diǎn)補(bǔ)償控制延時(shí)的方法,通過(guò)預(yù)測(cè)控制算法得到占空比和增加零極點(diǎn),有效地補(bǔ)償了系統(tǒng)內(nèi)環(huán)數(shù)字延時(shí),使系統(tǒng)在有源阻尼方法下能有效地起到增強(qiáng)阻尼的作用,設(shè)計(jì)簡(jiǎn)單,穩(wěn)定性加強(qiáng),仿真驗(yàn)證了其可行性和有效性。同時(shí)本文搭建了并網(wǎng)逆變系統(tǒng)實(shí)驗(yàn)平臺(tái),針對(duì)本文討論的問(wèn)題進(jìn)行了實(shí)驗(yàn)驗(yàn)證,增強(qiáng)其說(shuō)服力。
[Abstract]:In order to make the electric energy produced by the new energy system stable and efficiently integrated into the power grid, high-order filters with good performance have been widely used in grid-connected inverters between the new energy system and the power grid. But the high order LCL filter has its own resonance problem which affects the performance of grid-connected inverter interface equipment. The traditional grid-connected inverter resonance suppression problem is mostly studied and analyzed in analog domain. However, with the rapid development of digital signal processing technology and digital chip, digital control is gradually replacing analog control, and the effect of delay on system stability can not be ignored. In this paper, the discrete mathematical model of grid-connected inverter with time delay, digital current single loop and double loop active damping resonance suppression control are systematically analyzed and discussed. The discrete mathematical model of LCL grid-connected inverter considering digital delay link is analyzed and built. In continuous domain and discrete domain, the stability of grid-side current single-loop control is compared and analyzed, which shows that the digital delay link changes the stability of the system. Based on this, the digital delay is set as one beat lag in the feedback control of single loop of current on the grid side. The influence of the ratio of sampling frequency to resonant frequency on the stability of sampling frequency and resonance frequency is analyzed, and the stability range is determined. At the same time, the controller parameters are designed. Under the condition of low resonant frequency and sampling frequency, it is difficult to keep the stability of grid-side current digital single-loop control, which leads to the lack of robustness of grid-side current digital single-loop. Therefore, this paper further studies the digital capacitive current feedback active damping method to enhance the damping, and analyzes the influence of the digital delay of the inner loop caused by the digital capacitor current feedback on the active damping method. According to its influence, a method of predictive duty cycle and zero pole compensation control delay is put forward. Through predictive control algorithm, the duty cycle is obtained and zero pole is added, which effectively compensates the digital delay in the inner loop of the system. Under the active damping method, the system can effectively enhance the damping. The design is simple, the stability is enhanced, and the simulation proves its feasibility and effectiveness. At the same time, the experiment platform of grid-connected inverter system is built in this paper. Experiments are carried out on the problems discussed in this paper to enhance its persuasiveness.
【學(xué)位授予單位】:湘潭大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2017
【分類號(hào)】:TM464
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