【作者】 唐蕾；

【导师】 陈维荣；

【作者基本信息】 西南交通大学 ， 电力系统及其自动化， 2008， 博士

【摘要】 随着电力系统和牵引供电系统的发展,人们对电能质量的要求越来越高,电气化铁道牵引负荷大都为相控整流型负荷,具有功率因数低、谐波含量高、负序电流大等特点,对公用电网产生的影响较大,必须采取措施来改善电能质量。有源电力滤波器作为改善电能质量的有效手段之一,能较好地适应系统的变化,研究有源电力滤波器并把它应用于电气化铁道电能质量的改善中具有理论意义和实用价值。本文从矢量空间出发,在三维空间中建立坐标变换系统,通过严格的数学推导,得出三维空间中两个不同坐标系的等价变换关系,该变换系数即是瞬时无功功率理论所用坐标变换系数,新的坐标变换系统为理解瞬时无功功率理论所用坐标变换提供了指导。从电路理论的旋转相量出发,本文分析了基于瞬时无功功率理论的i_p-i_q谐波电流检测方法的检测原理,推导得出瞬时有功和无功电流的直流分量反映基波电流的信息,克服了直接代入推导法的计算繁琐并解决了畸变电压下要区分序电流的难题。本文分析了i_p-i_q法检测基波及基波有功电流产生误差的原因,在改进直流侧电容电压控制方案和新的基波有功电流检测方法的基础上,提出了一种工频、任意相位的无锁相环方案,完善了工频、零相位的传统无锁相环方案,解决了畸变电压下无锁相环的基波有功电流检测问题,实现了畸变电压下无锁相环方式谐波无功的综合补偿。论文从概率的角度探讨了直流侧电容电压参考值的选取原则,得出“直流侧参考电压应满足大于三倍系统电压峰值仅仅是有源电力滤波器正常工作的充分条件”的结论,对实际APF设计时器件的选取具有指导意义。本文对基于正余弦函数正交特性的单相电路基波电流分离检测法进行了改进,解决了单相电路畸变电压下无锁相环的基波有功电流检测问题。论文提出了一种新的应用瞬时无功功率理论的单相电路谐波电流直接检测方法,不需要延时环节构造三相系统来解决单相电路谐波电流的检测问题,减小了谐波电流检测的延时误差。本文通过频域下基于相量表示的对称分量法,对时域下基于瞬时值表示的对称分解算法进行了证明,为三相不对称负荷正序基波电流的检测提供了依据。结合时域下的对称分解算法,本文提出了一种采用有源电力滤波器实现电气化铁道不对称负荷谐波、无功和负序电流的综合补偿方案。该方案以电力系统三相侧电流为正序基波有功电流为目标,采用低压侧安装两套共用一个检测电路的单相有源电力滤波器装置来实现。检测电路检测到三相绕组(牵引侧为两相绕组的虚拟第三相绕组)的指令补偿电流,再按照牵引变压器三相侧电流与两供电臂电流间的关系式来分配两供电臂的指令补偿电流,由两套单相有源电力滤波器装置分别产生以实现补偿。通过以实测变电所电流数据建立的仿真系统可知,该方案能有效地补偿电气化铁道谐波、无功和负序电流,改善电气化铁道电能质量。更多还原

【Abstract】 With the development of power system and traction power system,the requirement for power quality is increasingly high by the people.Most of the traction loads in electrical railway are phased rectifier loads,with the features of low power factor and high harmonic contents and big negative sequence currents.The influences of those loads are bigger on the common grid.Measures must be taken to improve the power quality.As one of the effective methods to improve the power quality,active power filter can better adapt to the changes in the system.It has the theoretical significance and practical value to research the active power filter and apply it to the electrical railway for improving the power quality.Considering the vector space,this paper establishes the coordinate transformation system in the three-dimensional space.The equivalent transformation between two different coordinate systems is deduced through strict mathematical derivation.The transform coefficient is just the one that used in the instantaneous reactive power theory(IRPT).The new coordinate transform system provides a theoretical basis for the coordinate transform used in IRPT.From the point of rotate vector in circuit theory,this paper explains the detected principle of i_p-i_q method.It can be inferred that the DC parts of instantaneous active and reactive power reflect the information of fundamental current.This method resolves the problems of direct-inferred tediousness and distinguishing order currents under distortion voltage.The reasons of bringing errors to the fundamental active currents detection are analyzed in the paper.On the basis of the improvement capacitor voltage control scheme in the DC side and a new fundamental active current detection method,the phase locked loop is omitted and the power frequency and arbitrary angle are provided to detect the fundamental active current under distortion voltage.It can realize the integrative currents compensation without phase locked loop.From the angle of probability theory,the thesis discusses the criterion for DC voltage reference value.It concludes that the direct-current side reference voltage has to be bigger than three times of system voltage peak value is merely a sufficient condition for APF to work normally.It has the guiding significance for the device selection. The fundamental current separation method based on the orthogonal character of sin and cosine functions is improved.It resolves the problem of detecting the fundamental active current in single phase circuit under distortion voltage without phase locked loop.A new direct detection method based on IRPT is proposed in single-phase circuit for harmonic currents detection.There is no need to construct three- phase system by time-delay link.The delay error is reduced for harmonic currents detection.The symmetrical decomposition algorithm based on instantaneous value in time domain is derived from the symmetrical component method based on the phasor in frequency domain.It is verified and provides the basis for the positive sequence fundamental current detection of three-phase asymmetrical loads.This paper proposes a new scheme using active power filter combined with symmetrical decomposition algorithm to compensate the harmonic,reactive power and negative sequence currents in electrical railway.Making the three-phase currents be positive sequence fundamental active currents is the compensation target in the scheme.Two single-phase active power filter devices with common detection circuit are installed in the low-voltage side.The purpose of detection circuit is to get the directive compensation currents for three-phase windings.The directive compensation currents for each power arm are distributed according to the three-phase and two-phase relationship in traction transformer.The single-phase active power filters generate the compensation currents respectively.The simulation system is built with actual surveys by matlab.It’s verified that this method can realize the compensation for harmonic and reactive power even negative order currents and improve the traction power quality.更多还原