交直流混合微電網(wǎng)接口變換器控制研究
發(fā)布時(shí)間：2018-07-25 17:04
【摘要】：為了更加高效可靠地將交直流混合微電網(wǎng)的交直流母線互聯(lián),并且協(xié)調(diào)分配功率,接口變換器(Interface Converter,IC)�？刹捎貌⒙�(lián)運(yùn)行的方式。其中,并聯(lián)下垂特性控制策略的優(yōu)點(diǎn)包括:即插即用,為微網(wǎng)提供頻率和電壓支撐功能,可實(shí)現(xiàn)無通信時(shí)并聯(lián)運(yùn)行的各IC輸出功率自動(dòng)分配,并且在并離網(wǎng)模式下通用�；谶@些優(yōu)點(diǎn),下垂控制廣泛應(yīng)用于無互聯(lián)線的IC并聯(lián)系統(tǒng)中。此外,基于虛擬同步發(fā)電機(jī)(Virtual Synchronous Generator,VSG)技術(shù)的IC控制策略在實(shí)現(xiàn)下垂特性控制的同時(shí),能夠模擬同步發(fā)電機(jī)的運(yùn)行方式且為系統(tǒng)提供阻尼和慣性,成為一個(gè)研究熱點(diǎn)。本文對交直流混合微電網(wǎng)接口變換器的倒下垂控制策略和虛擬同步機(jī)控制策略分別進(jìn)行了深入研究。首先,根據(jù)交直流混合微電網(wǎng)中接口變換器的運(yùn)行特點(diǎn),模擬電力系統(tǒng)中同步發(fā)電機(jī)三次調(diào)頻的運(yùn)行方式,本文提出了一種改進(jìn)的倒下垂控制策略。文中仔細(xì)分析了改進(jìn)的倒下垂控制原理和相應(yīng)的微電網(wǎng)三次調(diào)節(jié)方法。通過在倒下垂控制環(huán)中加入積分環(huán)節(jié)進(jìn)行二次調(diào)節(jié),實(shí)現(xiàn)交流母線電壓和頻率的無差自動(dòng)調(diào)節(jié);通過改變倒下垂控制環(huán)中有功和無功功率基準(zhǔn)值來響應(yīng)上層控制系統(tǒng)的功率調(diào)度,也即進(jìn)行三次調(diào)節(jié),實(shí)現(xiàn)微電網(wǎng)的功率優(yōu)化分配。本文通過在DigSILENT/PowerFactory中搭建的微網(wǎng)模型進(jìn)行仿真分析,驗(yàn)證了所提控制策略的準(zhǔn)確性和有效性。其次,相比于倒下垂控制策略,虛擬同步機(jī)技術(shù)的應(yīng)用使得IC不僅能夠模擬三次調(diào)頻的運(yùn)行方式,而且能夠模擬同步機(jī)的內(nèi)部機(jī)制。本文針對VSG技術(shù)及其在交直流混合微電網(wǎng)IC并聯(lián)系統(tǒng)中的應(yīng)用進(jìn)行研究,提出了一種VSG等效模型與控制策略。首先根據(jù)低壓交直流混合微電網(wǎng)的結(jié)構(gòu)特點(diǎn),建立了直流子網(wǎng)與阻感性饋線組合等效同步發(fā)電機(jī)的VSG模型,并據(jù)此在VSG控制中加入虛擬電阻補(bǔ)償和虛擬坐標(biāo)變換。然后,通過在VSG功率環(huán)中加入電壓和功率基準(zhǔn)修正量來響應(yīng)微電網(wǎng)上層控制系統(tǒng)的調(diào)度,使得VSG能夠模擬同步發(fā)電機(jī)三次調(diào)頻的運(yùn)行方式;通過虛擬阻抗法解決了復(fù)雜供電網(wǎng)絡(luò)下VSG控制策略難以適用的問題。最后,通過仿真分析驗(yàn)證了所提VSG控制策略的準(zhǔn)確性和有效性,并在10kVA的儲(chǔ)能接口變換器實(shí)驗(yàn)平臺上進(jìn)行了 VSG基本功能的實(shí)驗(yàn)驗(yàn)證。最后,關(guān)于VSG的預(yù)同步并網(wǎng)方式,基于鎖相環(huán)(Phase Locked Loop,PLL)的方法由于所采用的PI調(diào)節(jié)器會(huì)引起多VSG系統(tǒng)的動(dòng)態(tài)環(huán)流和功率振蕩,難以滿足預(yù)同步過程的快速性和穩(wěn)定性要求。本文提出一種基于虛擬功率環(huán)和虛擬功率階躍給定的開環(huán)相位預(yù)同步方法,該方法無需鎖相環(huán)且VSG在預(yù)同步過程中具有良好的慣性和阻尼性能。首先對增加的VSG虛擬功率環(huán)的功能和虛擬功率階躍給定的開環(huán)并網(wǎng)方式進(jìn)行分析,指出預(yù)同步過程中的相角差值計(jì)算公式、預(yù)同步時(shí)間計(jì)算方法。其次,采用小信號模型對多VSG預(yù)同步過程中的有功環(huán)流問題進(jìn)行理論分析,通過雙功率環(huán)參數(shù)的分別整定來減小動(dòng)態(tài)環(huán)流。最后,通過仿真和實(shí)驗(yàn)對比了不同預(yù)同步方法的預(yù)同步過程,結(jié)果表明本文所提方法在保持調(diào)整精度的同時(shí)調(diào)節(jié)過程平滑穩(wěn)定,適用于多VSG的預(yù)同步控制。
[Abstract]:In order to connect the AC and DC bus of AC and DC hybrid microgrids more efficiently and reliably, and to coordinate the power distribution, the Interface Converter (IC) can often be operated in parallel. The advantages of the parallel droop characteristic control strategy include: plug and play, provide the frequency and voltage support for the micronetwork. The IC output power of the parallel operation is automatically allocated and used in the network mode. Based on these advantages, the droop control is widely used in the IC parallel system without interconnected lines. In addition, the IC control strategy based on the Virtual Synchronous Generator (VSG) technology is able to control the droop characteristics and can be used to control the droop characteristics. It is a research hotspot to simulate the operation mode of synchronous generator and provide damping and inertia for the system. In this paper, the inverted droop control strategy of AC DC hybrid microgrid interface converter and the control strategy of virtual synchronizer are studied. First, according to the operation characteristics of the interface converter in the AC and DC hybrid microgrid, In this paper, an improved inverted droop control strategy is proposed in this paper. In this paper, an improved inverted droop control strategy is proposed. In this paper, the improved inverted droop control principle and the corresponding three adjustment methods of the microgrid are carefully analyzed. The AC bus voltage is realized by adding the integral loop joint in the inverted droop control loop to achieve the AC bus voltage two times. In response to the power scheduling of the upper control system by changing the active and reactive power datum in the inverted droop control loop, the power dispatch of the upper control system can be adjusted to achieve the optimal power distribution of the microgrid. In this paper, the simulation analysis of the microgrid model built in DigSILENT/PowerFactory has been carried out to verify the control of the proposed control. The accuracy and effectiveness of the strategy. Secondly, compared to the inverted droop control strategy, the application of the virtual synchronizer technology makes IC not only can simulate the operation mode of three frequency modulation, but also can simulate the internal mechanism of the synchronous machine. This paper studies the VSG technology and its application in the IC parallel system of AC and DC hybrid microgrid. A VSG equivalent model and control strategy. First, based on the structure characteristics of the low voltage AC / DC hybrid microgrid, the VSG model of the combined equivalent synchronous generator of the DC subnet and the resistive feeder is established, and the virtual resistance compensation and the virtual coordinate transformation are added to the VSG control. Then, the voltage and power are added to the VSG power loop. In response to the scheduling of the microelectric network layer control system, the VSG can simulate the operation mode of the three frequency modulation of the synchronous generator. Through the virtual impedance method, the problem that the VSG control strategy is difficult to apply under the complex power supply network is solved. Finally, the accuracy and effectiveness of the proposed VSG control strategy are verified by the simulation analysis. The experimental verification of the basic functions of VSG is carried out on the experimental platform of 10kVA's energy storage interface converter. Finally, the method of pre synchronization and grid connection of VSG, based on the Phase Locked Loop (PLL) method, will cause the dynamic circulation and the power rate oscillation of the multiple VSG system because of the PI regulator adopted, so it is difficult to meet the speed and stability of the pre synchronization process. In this paper, an open loop phase pre synchronization method based on a virtual power loop and a virtual power step is proposed. This method does not require a phase-locked loop and the VSG has good inertia and damping performance during the pre synchronization process. First, the function of the added VSG virtual power loop and the given open loop parallel connection mode of the virtual power step are given. The calculation formula of the difference of phase angle in the pre synchronization process and the method of calculating the pre synchronization time are pointed out. Secondly, a small signal model is used to analyze the active circulation problem in the process of multi VSG pre synchronization, and the dynamic circulation is reduced by the separation of the parameters of the double power ring. The results show that the proposed method can maintain the adjustment accuracy while adjusting the process smoothly and stably, and is suitable for multi VSG presynchronous control.
【學(xué)位授予單位】：北方工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM727;TM46
本文編號：2144470
[Abstract]:In order to connect the AC and DC bus of AC and DC hybrid microgrids more efficiently and reliably, and to coordinate the power distribution, the Interface Converter (IC) can often be operated in parallel. The advantages of the parallel droop characteristic control strategy include: plug and play, provide the frequency and voltage support for the micronetwork. The IC output power of the parallel operation is automatically allocated and used in the network mode. Based on these advantages, the droop control is widely used in the IC parallel system without interconnected lines. In addition, the IC control strategy based on the Virtual Synchronous Generator (VSG) technology is able to control the droop characteristics and can be used to control the droop characteristics. It is a research hotspot to simulate the operation mode of synchronous generator and provide damping and inertia for the system. In this paper, the inverted droop control strategy of AC DC hybrid microgrid interface converter and the control strategy of virtual synchronizer are studied. First, according to the operation characteristics of the interface converter in the AC and DC hybrid microgrid, In this paper, an improved inverted droop control strategy is proposed in this paper. In this paper, an improved inverted droop control strategy is proposed. In this paper, the improved inverted droop control principle and the corresponding three adjustment methods of the microgrid are carefully analyzed. The AC bus voltage is realized by adding the integral loop joint in the inverted droop control loop to achieve the AC bus voltage two times. In response to the power scheduling of the upper control system by changing the active and reactive power datum in the inverted droop control loop, the power dispatch of the upper control system can be adjusted to achieve the optimal power distribution of the microgrid. In this paper, the simulation analysis of the microgrid model built in DigSILENT/PowerFactory has been carried out to verify the control of the proposed control. The accuracy and effectiveness of the strategy. Secondly, compared to the inverted droop control strategy, the application of the virtual synchronizer technology makes IC not only can simulate the operation mode of three frequency modulation, but also can simulate the internal mechanism of the synchronous machine. This paper studies the VSG technology and its application in the IC parallel system of AC and DC hybrid microgrid. A VSG equivalent model and control strategy. First, based on the structure characteristics of the low voltage AC / DC hybrid microgrid, the VSG model of the combined equivalent synchronous generator of the DC subnet and the resistive feeder is established, and the virtual resistance compensation and the virtual coordinate transformation are added to the VSG control. Then, the voltage and power are added to the VSG power loop. In response to the scheduling of the microelectric network layer control system, the VSG can simulate the operation mode of the three frequency modulation of the synchronous generator. Through the virtual impedance method, the problem that the VSG control strategy is difficult to apply under the complex power supply network is solved. Finally, the accuracy and effectiveness of the proposed VSG control strategy are verified by the simulation analysis. The experimental verification of the basic functions of VSG is carried out on the experimental platform of 10kVA's energy storage interface converter. Finally, the method of pre synchronization and grid connection of VSG, based on the Phase Locked Loop (PLL) method, will cause the dynamic circulation and the power rate oscillation of the multiple VSG system because of the PI regulator adopted, so it is difficult to meet the speed and stability of the pre synchronization process. In this paper, an open loop phase pre synchronization method based on a virtual power loop and a virtual power step is proposed. This method does not require a phase-locked loop and the VSG has good inertia and damping performance during the pre synchronization process. First, the function of the added VSG virtual power loop and the given open loop parallel connection mode of the virtual power step are given. The calculation formula of the difference of phase angle in the pre synchronization process and the method of calculating the pre synchronization time are pointed out. Secondly, a small signal model is used to analyze the active circulation problem in the process of multi VSG pre synchronization, and the dynamic circulation is reduced by the separation of the parameters of the double power ring. The results show that the proposed method can maintain the adjustment accuracy while adjusting the process smoothly and stably, and is suitable for multi VSG presynchronous control.
【學(xué)位授予單位】：北方工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM727;TM46
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