【作者】 王鑫；

【导师】 涂春鸣；

【作者基本信息】 湖南大学 ， 电气工程， 2024， 博士

【摘要】 截止至2023年底,我国铁路营业里程达15.9万公里,电气化率达75.2%,铁路机车拥有量2.24万台。铁路路网规模的持续扩大对电气化铁路的高速化、重载化与低碳化等方面提出更高的要求。目前,电气铁路多采用异相牵引供电模式,即通过牵引变压器将220/110k V三相电网电压降低为27.5kV两相牵引网电压,并采用电分相对相邻供电区进行电气隔离。然而,电分相作为牵引供电系统的薄弱环节,其存在会引发过分相电弧、列车速度损失与再生制动能量浪费等问题。此外,由于单相牵引负荷的不对称性与冲击性,异相牵引供电模式为三相电网带来了严重的负序、无功、谐波等电能质量问题。为突破传统牵引供电系统中电分相与电能质量桎梏,实现牵引供电系统低碳供能与高效用能,本文在国家重点研发计划“轨道交通“网-源-储-车”协同供能技术(2021YFB2601500)”的资助下,研究了集成新能源与储能的新型混合式贯通牵引供电系统及其运行控制方法,形成了所提系统的拓扑架构、装置控制、容错运行与能量管理四个方面系列创新性成果。本文具体研究工作及其创新点归纳如下:(1)创新性提出了面向“存量”和“增量”牵引站的工频隔离型与高频隔离型新型混合式贯通牵引供电装置(Novel hybrid advanced traction power suppl y device,NH-ATPSD)拓扑架构,破解了既有贯通牵引供电装置存在的器件数目多、改造成本高、功率密度低等难题。所提工频隔离型NH-ATPSD采用两相输入端口多重化共直流侧-单相输出端口多模块级联结构,有效减少改造所需有源/无源器件数目与直流侧电容容量,大幅降低贯通系统改造成本;所提高频隔离型NH-ATPSD采用三端口隔离型DC-DC变换器连接两相输入与单相输出侧,在减小装置体积的同时提升系统功率密度,减小贯通系统改造成本。其次,结合工程实际验证算例从器件数目、器件选型、改造成本、装置体积、运行效率、功率密度等方面详细对比既有方案与所提拓扑的优劣。结果表明,所提工频隔离型NH-ATPSD成本最低、可靠性最高、工程应用优势突出,而所提高频隔离型NH-ATPSD体积最小、功率密度最大,可适用于对场地空间需求较高的场景。最后,根据投资成本、可靠性与工程成熟度情况,本文选择工频隔离型NH-ATPSD作为后文研究基础。(2)提出了面向直流侧电压稳定的两相输入端口对等复合控制策略与面向牵引网稳定的单相输出端口改进arctan下垂控制策略,解决稳态工况下新型混合式贯通牵引供电系统中两相输入功率均分、直流侧电压稳定、纹波传递、牵引网频率与电压支撑等问题。首先,基于牵引变压器接线方式,研究工频隔离型NH-ATPSD内部功率流动特性,解析电网侧负序电流与直流侧电压纹波形成原因,对负序电流与输入功率、二次纹波与直流电容间关系进行定量刻画。其次,提出一种面向两相输入端口的对等复合控制策略,在实现功率均分与纹波传递抑制前提下,采用两相输入端口同时控制直流母线电压的方式,抑制直流侧电压波动,提高系统供电可靠性。最后,为解决传统比例下垂控制易出现电压与频率越限问题,提出了输出端口改进arctan下垂控制策略,实现牵引网电压与频率连续调节,保证牵引网电压与频率稳定在规定区间。(3)提出面向NH-ATPSD内部模块故障的主动容错控制与面向外部端口故障的应急管控技术,在无需增加任何投资成本情况下,充分利用既有健康模块与设备,实现NH-ATPSD内部模块故障与外部端口故障的容错运行。首先,全面分析NH-ATPSD中输入与输出端口的内部单模块故障特性,结果显示在输入模块故障下系统将出现负序电流、功率越限现象,而在输出模块故障下系统输出电压与功率受到影响。为此,本文提出一种动态调制系数与功率局部不平衡控制方法,通过健康模块间的功率协调有效解决健康模块功率越限与网侧负序电流等问题。其次,针对NH-ATPSD输入/输出外部端口故障问题(指发生多模块或短路等故障致使整个外部端口无法满足电压或功率需求的情况),综合考虑子牵引站中既有设备应急管控潜能,通过既有的牵引变压器、联络开关、“两相-单相”变换单元等系统既有装置间的协同配合,实现在不同外部端口故障工况下装置100%额定功率运行与负序电流抑制。(4)提出基于NH-ATPSD的“网源储车”多时间尺度高效能量管理策略,通过min级总站集群优化调度与s级子站实时自治控制协同配合,解决贯通牵引供电系统高效、高质、实时、高可靠运行难题。首先,考虑列车与新能源功率的不确定性与实时波动特性,设计了基于分钟(min)级总站集群优化调度与秒(s)级子站实时自治控制的双时间尺度实时管控架构,兼顾系统运行的经济性与可靠性。其次,在min级总站集群优化调度层面,基于源荷的min级预测数据,以贯通系统运行成本最低为优化目标,求解各子牵引站的最优参考运行点,保证贯通系统全局最优经济运行。最后,在s级子站实时自治控制层面,针对预测功率与实时功率误差导致的系统电压/频率越限、功率反馈等问题,提出基于改进arctan下垂控制的自适应运行调控策略。在总站最优参考运行点的基础上结合子站实时运行状态修正各设备单元参考功率点,保证系统可靠运行同时,有效解决预测-实际功率误差所造成的系统功率倒送问题。总之,本文依据电气化铁路在高效、高质、可靠、经济运行方面的要求,以集成新能源与储能的新型混合式贯通牵引供电系统架构为核心,在装置拓扑、控制技术、容错运行以及能量管理等方面开展了系统性研究。旨在突破贯通供电系统改造成本高、体积大、可靠性低、运行经济性差的桎梏,为牵引供电系统未来发展提供有益参考和借鉴。更多还原

【Abstract】 As of the end of 2023,the operational railway mileage in China has reached 159,000 kilometers,with an electrification rate of 75.2%and The ownership of railway locomotives is 22,400 units.The continuous expansion of the railway network imposes higher requirements on the electrified railway system in terms of high-speed,heavy-duty,and carbon reduction.Presently,in electrified railways,the preferred mode of traction power supply is the two-phases traction mode,where a traction transformer steps down the voltage from the 220/110kV three-phase grid to 27.5kV two-phase traction grid.Additionally,the neutral section is employed between adjacent power supply sections.However,the presence of neutral section as a vulnerable aspect of the traction power supply system can lead to issues such as electric arcs,train speed losses,and wastage of regenerative braking energy.Furthermore,due to the asymmetry and impact of single-phase traction loads,the asymmetrical phase traction power supply mode introduces significant power quality issues such as negative sequence,reactive power,and harmonic distortions to the three-phase grid.To break free from the constraints imposed by the traditional traction power supply systems,particularly concerning electrical separation and power quality,and to achieve low-carbon and efficient energy utilization in traction power supply systems,this study,supported by the National Key R&D Program"Synergetic Supply of Power for Rail Transportation System(2021YFB2601500)",investigates a novel hybrid advanced traction power supply system incorporating new energy sources and energy storage,along with its operational control methods.This research has resulted in a series of innovative achievements in four aspects:topology architecture,device control,fault-tolerant operation,and energy management of the proposed system.The specific research work and its innovative aspects are summarized as follows:(1)A novel hybrid advanced traction power supply device(NH-ATPSD),designed for both existing "stock" and new "incremental" traction sub-stations,is innovatively proposed.This device addresses challenges inherent in conventional advanced traction power supply devices,such as high component count,elevated retrofit costs,and low power density.The proposed low-frequency isolation-type NH-ATPSD employs a two-phase input port with a common direct current(DC)side and a single-phase output port with a multi-module cascade structure.This configuration significantly reduces the number of active/passive components required for retrofitting and diminishes the DC-side capacitor capacity,consequently lowering the overall retrofitting costs.On the other hand,the proposed high-frequency isolation-type NH-ATPSD utilizes a three-port isolation DC-DC converter connecting the two-phase input to the single-phase output,enhancing system power density while reducing device size and retrofitting costs.Furthermore,a comprehensive comparison between the existing schemes and the proposed topologies is conducted,considering aspects such as component count,component selection,retrofitting costs,device size,operational efficiency,and power density,based on practical engineering considerations.The results demonstrate that the proposed low-frequency isolation-type NH-ATPSD exhibits the lowest cost,highest reliability,and outstanding engineering applicability,whereas the proposed high-frequency isolation-type NH-ATPSD offers the smallest volume and highest power density,suitable for scenarios with stringent space constraints.Finally,considering investment costs,reliability,and engineering maturity,this paper selects the low-frequency isolation-type NH-ATPSD as the foundation for subsequent research.(2)A peer-to-peer composite control of input ports targeting DC side voltage stability and improved arctan droop control of output port targeting traction network stability are proposed,addressing the issues of equitable power sharing between the two-phase inputs,DC side voltage stability,ripple propagation,and traction network frequency and voltage support in steady-state conditions within the novel hybrid advanced traction power supply system.Initially,based on the traction transformer connection method,the internal power flow characteristics of the low-frequency isolation-type NH-ATPSD are investigated to analyze the causes of negative sequence current on the grid side and ripple formation on the DC side,quantitatively characterizing the relationship between negative sequence current and input power,and between secondary ripple and DC capacitance.Subsequently,a symmetrical composite control strategy is proposed for the two-phase input ports,aiming to achieve power sharing and ripple suppression while simultaneously controlling the DC bus voltage at both input ports,thereby mitigating DC side voltage fluctuations and enhancing system supply reliability.Finally,to address the common issue of voltage and frequency excursions associated with traditional proportional droop control,an improved arctan droop control strategy for the output port is introduced,enabling continuous adjustment of traction network voltage and frequency to ensure their stability within specified limits.(3)An active fault-tolerant control aimed at internal module faults within the NH-ATPSD and emergency management techniques targeting external port faults are proposed.These approaches utilize existing healthy modules and equipment to achieve fault-tolerant operation for both internal module failures and external port malfunctions without requiring additional investment costs.Initially,an in-depth analysis of the characteristics of single-module faults in the input and output ports of the NH-ATPSD is conducted.The analysis reveals that under input module faults,the system experiences negative sequence currents and power excursions,while output module faults affect system output voltage and power.Consequently,a dynamic modulation coefficient and local power imbalance control method are proposed in this paper.This method effectively resolves issues such as power excursions in healthy modules and grid-side negative sequence currents through power coordination among healthy modules.Subsequently,addressing external port faults of the NH-ATPSD(which refer to situations where multiple modules or short circuits occur,leading to the inability of the entire external port to meet voltage or power requirements),the paper considers the emergency management potential of existing equipment in substation.Through coordinated cooperation among existing devices such as traction transformers,contact switches,and "two-phase to single-phase"conversion units,the system ensures operation at 100%rated power and suppression of negative sequence currents under different external port fault conditions.(4)A multi-timescale efficient energy management strategy based on NH-ATPSD for the "grid-source-storage-vehicle" system is proposed,aiming to address challenges in achieving efficient,high-quality,real-time,and highly reliable operation of the advanced traction power supply system.Firstly,considering the uncertainty and real-time fluctuations of train and new energy power,a dual-time-scale real-time control architecture is designed based on cluster optimization scheduling at the minute(min)level for main stations and real-time autonomous control at the second(s)level for sub-stations,balancing the economic and reliable operation of the system.Secondly,at the cluster optimization scheduling level for main stations,utilizing minute-level predictive data of the source-load and optimizing the operation cost of the system as the objective,the optimal reference operating points for each sub-traction station are determined to ensure global optimal economic operation of the system.Finally,at the real-time autonomous control level for sub-stations,to address issues such as voltage/frequency excursions and power feedback caused by errors between predicted and real-time power,an adaptive operation control strategy based on improved arctan droop control is proposed.Combining the optimal reference operating points from the main station with real-time operation status adjustments of each equipment unit in the sub-stations ensures system reliability while effectively resolving power backflow issues caused by prediction-to-reality power errors.In summary,this paper,based on the requirements of efficient,high-quality,reliable,and economical operation of electrified railways,focuses on the integrated new energy and energy storage hybrid advanced traction power supply system architecture.It systematically investigates device topology,control techniques,fault-tolerant operation,and energy management.The aim is to overcome the constraints of high retrofitting costs,large volume,low reliability,and poor economic performance of advanced traction power supply systems,providing valuable references and insights for the future development of traction power supply systems.更多还原