基于五电平三相—单相变换器的多牵引变电所并网控制研究

发布时间：2018-02-25 07:24

本文关键词： 贯通式同相供电系统三相-单相变换器牵引网阻抗变电所间自动均流多牵引变电所并网控制　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：由于机车负载容量的增大,现行铁路牵引供电系统无功、谐波、三相不平衡等问题日益突出,过分相的存在使机车运行速度及电能质量大大降低。基于三相-单相变换器的贯通式同相供电系统是一种新型的牵引供电系统,其通过可控电力电子器件实现三相/单相变换,可彻底取消过分相装置,实现牵引网的全线贯通,因此受到了广泛的关注。本文主要对基于五电平二极管钳位三相-单相变换器的多牵引变电所并网进行研究,从理论、仿真、实验等方面验证了整个系统并网的可行性。首先,研究了三相五电平二极管钳位整流器的拓扑结构及数学模型,并基于其端口电压的数学模型采用三相dq解耦的控制策略;分析了单相五电平二极管钳位整流器的拓扑结构及数学模型,并根据控制模型采用简化改进的单相pq分解控制策略,其能够可靠的调节交流侧无功功率的输出;研究了直流侧均压的控制方式以及变换器的调制策略。其次,研究了并网的拓扑结构,提出了基于可控逆变电压源及可控功率源的全电力电子器件的混合并网系统。计算牵引网阻抗,并分析了牵引网阻抗对功率源输出电压的影响;研究了两变电所之间的环流特性,基于下垂控制的思想提出了一种适用于牵引供电的并网控制策略,并对并网控制器进行了设计,相对于传统下垂控制方案受限于它的固定系数而无法快速调节变电所功率输出的不足,该方案能根据机车负载的投切来实时监测变电所与牵引网连接处电压相位与幅值变化,得到所需的有功电流及无功电流的参考值,从而控制各个牵引变电所的功率输出。在上述研究的基础上,本文通过Matlab/Simulink对两个变电所及三个变电所并网系统分别进行了仿真,仿真结果表明在机车负载投入或者切除时,所提出的并网控制策略都能实时控制各个牵引变电所的功率输出,保持各牵引变电所输出幅值、相位、频率一致的交流电压并入牵引网,最终实现多牵引变电所的贯通并网及稳定运行,稳态及动态性能良好。最后,设计了基于现场可编辑逻辑门阵列(FPGA)控制器的低电压小功率实验平台,分别进行了三相五电平二极管钳位整流实验、单相五电平二极管钳位整流实验、三相-单相背靠背系统并网实验以及两个牵引变电所并网实验,实验结果验证了主电路拓扑结构、三相和单相侧控制策略以及并网控制策略的合理性和可行性。
[Abstract]:Due to the increase of locomotive load capacity, the problems of reactive power, harmonics and three-phase imbalance in the current railway traction power supply system are becoming increasingly prominent. The running speed and power quality of locomotive are greatly reduced by the existence of excessive phase. The through-through in-phase power supply system based on three-phase single-phase converter is a new type of traction power supply system, which realizes three-phase / single-phase conversion through controllable power electronic devices. It can completely cancel the over-phase device and realize the whole line connection of the traction network, so it has received extensive attention. This paper mainly studies the grid-connected multi-traction substation based on the five-level diode clamping three-phase single-phase converter, from the theory, the simulation, The feasibility of the whole system is verified by experiments. Firstly, the topology and mathematical model of three-phase five-level diode clamping rectifier are studied, and the three-phase dq decoupling control strategy is adopted based on the mathematical model of port voltage. The topology and mathematical model of single-phase five-level diode clamping rectifier are analyzed. According to the control model, a simplified single-phase PQ decomposition control strategy is adopted, which can reliably adjust the output of AC side reactive power. The control mode of DC side voltage sharing and the modulation strategy of converter are studied. Secondly, the topology of grid-connected network is studied. A hybrid grid-connected system of all power electronic devices based on controllable inverter voltage source and controllable power source is proposed. The traction network impedance is calculated and the influence of traction network impedance on the output voltage of power source is analyzed. This paper studies the circulation characteristics between two substations, proposes a grid-connected control strategy suitable for traction power supply based on the idea of droop control, and designs a grid-connected controller. Compared with the traditional droop control scheme, which is limited by its fixed coefficient, it can not adjust the power output of the substation quickly. The scheme can real-time monitor the voltage phase and amplitude change at the junction of substation and traction network according to the switching of locomotive load. The reference values of active current and reactive current are obtained to control the power output of each traction substation. Based on the above research, the grid-connected systems of two substations and three substations are simulated by Matlab/Simulink. The simulation results show that the proposed grid-connected control strategy can control the power output of each traction substation in real time and maintain the output amplitude and phase of the traction substation when the locomotive load is put into or removed. The AC voltage with the same frequency is incorporated into the traction network to realize the connection and stable operation of the multi-traction substation, and the steady and dynamic performance is good. Finally, A low-voltage low-power experimental platform based on field editable logic gate array (FPGA) controller is designed. The experiments of three-phase five-level diode clamping rectifier and single-phase five-level diode clamping rectifier are carried out respectively. Three-phase single-phase back-to-back system grid-connected experiments and two traction substation grid-connected experiments the experimental results verify the topology of the main circuit three-phase and single-phase side control strategy and grid-connected control strategy rationality and feasibility.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U224

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