本文選題：三相逆變器　切入點(diǎn)：虛擬同步發(fā)電機(jī)　出處：《哈爾濱工業(yè)大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：對(duì)于分布式發(fā)電設(shè)備,既要并網(wǎng)時(shí)跟蹤功率給定,又能在電網(wǎng)故障時(shí)孤島運(yùn)行保證重要負(fù)荷的供電。而矢量電流控制方法只能并網(wǎng)運(yùn)行,孤島時(shí)通常采用下垂控制,模式切換時(shí)由電流型控制變?yōu)殡妷盒涂刂?結(jié)構(gòu)復(fù)雜。矢量控制過快的響應(yīng)還導(dǎo)致像LC諧振等穩(wěn)定問題。而虛擬同步發(fā)電機(jī)(VSG)是電壓型控制,并網(wǎng)孤島均可,并離網(wǎng)切換時(shí)快速且電流無沖擊。不同于下垂控制,VSG控制加入虛擬慣量和頻率阻尼,可以調(diào)節(jié)功率的響應(yīng)時(shí)間,減小電流沖擊,提高功率和頻率的抗擾能力及系統(tǒng)的穩(wěn)定性。弱電網(wǎng)下,VSG還能支撐電網(wǎng)電壓的頻率和幅值。本文首先建立了三相PWM并網(wǎng)逆變器在三相靜止、兩相靜止和同步旋轉(zhuǎn)坐標(biāo)下的電路模型,介紹了虛擬同步發(fā)電機(jī)控制的原理和傳統(tǒng)控制結(jié)構(gòu),鑒于鎖相環(huán)帶來的穩(wěn)定問題,提出了正常運(yùn)行中不用鎖相環(huán)且電壓參考由幅值乘功角得來的控制結(jié)構(gòu),并在無功控制的前向通道加入一階慣性來增加穩(wěn)定性。根據(jù)并網(wǎng)時(shí)頻率偏差小于1%的穩(wěn)態(tài)要求,得到頻率阻尼的選取原則,由簡(jiǎn)化一階慣性環(huán)節(jié)的調(diào)節(jié)時(shí)間或二階系統(tǒng)的阻尼大小和調(diào)節(jié)時(shí)間來確定慣量。虛擬同步發(fā)電機(jī)控制回路為二階系統(tǒng),不同的阻尼大小會(huì)使動(dòng)態(tài)響應(yīng)不一樣,比如阻尼太大導(dǎo)致調(diào)節(jié)時(shí)間變長(zhǎng),太小又會(huì)引起超調(diào)。本文分析了功率階躍時(shí)虛擬慣量、阻尼大小對(duì)有功功率和頻率響應(yīng)的影響,無功控制PI系數(shù)和慣性常數(shù)對(duì)無功功率和幅值響應(yīng)的影響。預(yù)同步控制用于發(fā)電設(shè)備無沖擊并入電網(wǎng),分析了現(xiàn)有方法的缺點(diǎn),改進(jìn)的方法中加入相角差濾波,頻率參考中減去其比例,就能將相角差調(diào)至零附近,減小了啟動(dòng)電流和功率反向。另外功率反向也可加入頻率下垂環(huán)節(jié),改變系數(shù)大小和正負(fù)來抑制。常規(guī)PWM變換器控制的穩(wěn)定性問題包括高頻諧振和次同步振蕩,而虛擬同步發(fā)電機(jī)存在工頻振蕩。本文分別建立了有功功率-功角和無功功率-幅值控制的開環(huán)傳函,得到了整體的矩陣開環(huán)傳函,用波特圖分析發(fā)現(xiàn)在50Hz處存在諧振,采用虛擬阻抗和電流高通反饋抑制了工頻振蕩。為了驗(yàn)證理論分析和所提方法在實(shí)際環(huán)境中的可行性,在現(xiàn)有的15kW三相PWM并網(wǎng)逆變器實(shí)驗(yàn)平臺(tái)上作了驗(yàn)證。完成了傳統(tǒng)和所提虛擬同步發(fā)電機(jī)控制方法的穩(wěn)態(tài)、動(dòng)態(tài)響應(yīng)、并離網(wǎng)切換、預(yù)同步控制和抑制工頻振蕩的實(shí)驗(yàn),實(shí)驗(yàn)結(jié)果表明分析和所提方法的有效性。
[Abstract]:For the distributed generation equipment, it is necessary to track the given power when connected to the grid, and to ensure the power supply of important load by island operation in the event of power network failure. However, the vector current control method can only be connected to the grid, and sagging control is usually used when the power is isolated. In mode switching, the current mode control becomes voltage mode control, and the structure is complex. The quick response of vector control also leads to stability problems such as LC resonance. The VSG control can adjust the response time of power and reduce the current shock, which is different from that of VSG control with virtual inertia and frequency damping. In this paper, a three-phase PWM grid-connected inverter is established in this paper, which can also support the frequency and amplitude of the grid voltage. The circuit model of two phase stationary and synchronous rotation coordinates is introduced. The control principle and traditional control structure of virtual synchronous generator are introduced. In view of the stability problems brought by PLL, A control structure without phase-locked loop and voltage reference obtained from amplitude-multiplying power angle in normal operation is proposed, and the first-order inertia is added to the forward channel of reactive power control to increase stability. According to the steady-state requirement of frequency deviation less than 1% in grid-connection, The selection principle of frequency damping is obtained. The inertia is determined by simplifying the regulating time of the first order inertial link or the damping and regulating time of the second order system. The control loop of the virtual synchronous generator is a second order system. Different damping levels make dynamic response different. For example, too much damping results in longer adjustment time, too small damping and overshoot. In this paper, the influence of virtual inertia and damping on active power and frequency response in power step is analyzed. The influence of Pi coefficient and inertia constant of reactive power control on reactive power and amplitude response. Pre-synchronous control is used to integrate the generation equipment without impact into the power network. The shortcomings of the existing methods are analyzed, and the phase angle difference filter is added to the improved method. By subtracting its proportion from the frequency reference, the phase angle difference can be adjusted to near zero, which reduces the starting current and power reverse. In addition, the power reverse can also be added to the frequency droop link. The stability problems of conventional PWM converter control include high frequency resonance and subsynchronous oscillation. In this paper, the open-loop transmission function of active power angle and reactive power amplitude control is established, and the integral matrix open-loop transmission function is obtained, and the resonance at 50Hz is found by Porter diagram analysis. Virtual impedance and current high pass feedback are used to suppress the power frequency oscillation. In order to verify the feasibility of the theoretical analysis and the proposed method in the actual environment, Based on the existing experimental platform of 15kW three-phase PWM grid-connected inverter, the experiments of steady-state, dynamic response, off-grid switching, pre-synchronization control and suppression of power frequency oscillation of traditional and proposed virtual synchronous generator control methods are completed. The experimental results show that the proposed method is effective.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TM464;TM31

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本文編號(hào)：1570178