【作者】 王远；

【导师】 何晓琼；

【作者基本信息】 西南交通大学 ， 电力电子与电力传动， 2013， 硕士

【摘要】 传统牵引供电系统采取三相-两相分相供电方式,存在着无功、谐波、负序等电能质量的技术难题,并且由于过分相装置的存在,大大制约着机车的运行速度和承载能力。随着高速,重载铁路的发展,该系统面临着严重挑战。基于此,本文研究了基于三电平三相—单相二极管钳位变换器的贯通式同相牵引供电系统。利用电力电子技术彻底取消过分相装置,实现三相负荷的对称以及牵引网侧的柔性可控,大大改善了电能质量,提高了系统效率,是一种新型的智能牵引供电系统。本文深入分析了贯通式同相供电系统的控制问题,讨论了三相—单相变换器的拓扑结构,研究了三相变换器及单相变换器的控制方法,对于三相变换器采用PI双闭环调节,并对直流电容进行均压控制。对于单相变换器,采用电压前馈并网控制。建立了变换器数学模型,并对控制系统的参数进行了整定,描绘了控制系统开闭环波特图,证明了系统的稳定性。建立新型牵引网Carson模型,讨论分析多机并网系统的阻抗分布,环流分布以及下垂性能,得出系统具有下垂特性,可以使用下垂控制实现多组变换器并联运行,选取了双闭环结构,对电流进行解耦,配置了控制系统参数,波特图证明系统达到稳定性要求,并实现了均流控制。由于机车作为谐波源会向系统注入大量谐电流,牵引供电系统成为最直接的谐波电流源激励对象,很可能对相关设备造成损害。因此,针对这一新型牵引供电系统进行谐波分析,建立了基于分布式电感电容降阶计算的牵引网阻抗模型,搭建了CRH2机车负载模型,进行了车网耦合仿真,分析了负载牵引网侧、变电所牵引网侧和三相电网输出侧的谐波情况,证明了该系统车网耦合时谐波满足国家标准要求,还分析了极端情况下大谐波电流注入的情况,该系统谐波情况优于现有供电系统,为避免谐波谐振提供相应的理论参考。为了验证该系统的相关性能及特性,利用Matlab/Simulink搭建系统仿真模型和谐波分析模型,对于三相-单相变换器单机并网和多机并联并网的情况进行建模和仿真,对于车网耦合的谐波情况进行了仿真。仿真结果表明该贯通式同相供电系统相比于现有的供电系统模型能更好地解决供电电能质量、谐波、无功及三相不平衡电流等问题,相对于现有系统优势明显。更多还原

【Abstract】 Traditional traction power supply system adopts three-phase to two-phase separation mode of power supply. This system is facing pool quality of power supply such as:reactive, harmonics, and negative sequence. And the phase splitting limits the capability of speed and load. With the development of high-speed, heavy--load railway, the system is facing severe tests.This paper introduces a advanced co-phase power supply system based on three level three-phase to single-phase converter, which uses power electronic technology to cancel the neutral-section passing device completely, to achieve the symmetrical of three-phase load and the traction network side flexible controllable.This system improves the quality of electric energy, raises the efficiency of the system and is a new type of smart traction power supply system.The control scheme of advanced co-phase traction power supply system is analyzed in this paper. First of all, the topology of three-phase to single-phase converter is discussed. Then the control of three-phase converter and single-phase converter are studied, the three-phase part adopts dual-loop PI control and the DC capacitor voltage balance while the single-phase part adopts voltage feed-forward control. The mathematical model of the converter is established, the control parameters are set and the bode figures of the system are depicting to prove the stability of the system.For the multi-substations model, Carson model of the system is established to analyze the impedance distribution and the circulation distribution to verify the droop characteristic of the system. Using droop control based on direct power control to achieve current decoupling, the control parameters are set and the bode figures of the system are depicting to prove the stability of the system, current sharing of substations parallel operation are achieved.As harmonic source, the locomotives inject huge harmonic current to the system, the traction power supply system becomes the direct encouraging object, which may cause the damage of equipments. So, it’s necessarily to analyze the harmonic impedance of the system based on distributed capacitance and inductance reduction, the locomotive model of CRH2is set up to simulate the locomotive network coupling, the harmonic of load, substations and grid power are analyzed, the results meet the national standard, the extreme case of injection high harmonic current is also taken into consideration, the simulation results shows that the harmonic performance of the system is better than the existing system and provides theoretical reference for avoiding harmonic resonance.To verify the performance and characteristics of the system, three-phase to single-phase converter operation, single substation and multi-substations grid-connected simulation model and harmonic analysis model are built in Matlab/Simulink environment. The simulation of locomotive network coupling is carried out. The simulation results show that the advanced co-phase traction power supply system can solve the problem of power quality, harmonic, reactive and three-phase unbalance current better, has the obvious superiority.更多还原