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Efficient Generation of Power in Medium Voltage Direct Current Systems: Variable Speed Operation and Rectifier Considerations.

机译：在中压直流系统中高效发电：变速操作和整流器注意事项。

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摘要

By investigating variable speed operation of an engine and different types of ac-dc rectifier topologies, this dissertation provides procedures to develop and implement efficient Medium Voltage Direct Current (MVDC) power systems. The research reported here offered solutions to the following issues: 1) Efficiency improvement of a gas turbine by running it in variable speed operation mode. 2) The advantages and disadvantages of different ac-dc rectifier topologies considering both the efficiency and rectifier performance (dc bus voltage regulation, weight/size/volume of passive components, number of semi-conductor devices, displacement power factor, complexity of control strategy, etc.) 3) Implementation of variable speed MVDC power system if variable speed operation brings great advantages for fuel saving.;A semi-theoretical analysis was developed to address issue 1). This analysis revealed the optimal efficiency and the corresponding optimal speed as a function of shaft load for both single-shaft and twin-shaft gas turbines. These semi-theoretical results were confirmed by detailed simulations that show it is possible to achieve as much as 15% reduction in fuel consumption when variable speed operation is used instead of fixed speed, for a generating plant to electrically propel a ship having powering characteristics similar to those of a DDG-51.;A series of boost type rectifiers for applications in MVDC power systems were compared to address issues 2). The comparison included only boost rectifiers since higher distribution voltage leads to higher efficiency. The boost type rectifiers are diode rectifier with boost chopper (diode rectifier), three-level diode clamped voltage source converter (VSC), and modular multilevel converter (MMC). The comparison metrics include complexity of control strategy, number of switching devices, number/value/weight/volume of inductors and capacitors, the dc bus voltage performance (peak-peak voltage ripple, overshoot, and settling time), the total harmonic distortion (THD) of the ac side input current and voltage, displacement power factor (DPF), power efficiency for different load conditions, and performance under variable ac frequency operation. The comparison shows that MMC is the most efficient and provides the best dc bus performance, by adding more capacitors (both number of capacitors and total weight), and more complex control schemes into the system. VSC provides a relative high efficiency and dc bus performance with less passive components, which indicates VSC is a good choice considering both performance and cost.;A procedure to implement an integrated variable speed MVDC power system was proposed to address issues 3). For each component of dc power generation chains, gas turbine, synchronous generator, and ac-dc rectifier, their steady-state efficiencies and system efficiency vs. dc load were analyzed. The relative system efficiency improvement (an index of fuel reduction) can be up to 35% for 10% loading. The relative efficiency improvement decreases to 5% as the dc load increases to 45% loading. Following the procedure, a variable speed MVDC power system simulation model was developed. The dynamic response shows that the system can track the speed command for different load demands while yielding the highest efficiency and good system stability.
机译：通过研究发动机的变速运行和不同类型的交流-直流整流器拓扑，本文提供了开发和实施有效的中压直流（MVDC）电力系统的程序。此处报告的研究为以下问题提供了解决方案：1）通过以变速运行模式运行燃气轮机来提高效率。 2）考虑效率和整流器性能（直流总线电压调节，无源组件的重量/尺寸/体积，半导体器件的数量，位移功率因数，控制策略的复杂性）的不同AC-DC整流器拓扑的优缺点3）如果变速操作为节省燃料带来很大优势，则实施变速MVDC电力系统。;针对问题1）进行了半理论分析。该分析揭示了单轴和双轴燃气轮机的最佳效率和相应的最佳转速与轴负荷的关系。这些详细的模拟结果证实了这些半理论的结果，这些模拟结果表明，当使用变速运行代替固定速度运行时，对于发电厂而言，用电力推动具有相似动力特性的船舶，可以将燃油消耗减少多达15％。与DDG-51的产品相比较；比较了一系列用于MVDC电力系统的升压型整流器，以解决问题2）。该比较仅包括升压整流器，因为更高的分配电压会导致更高的效率。升压型整流器是带有升压斩波器的二极管整流器（二极管整流器），三电平二极管钳位电压源转换器（VSC）和模块化多电平转换器（MMC）。比较指标包括控制策略的复杂性，开关设备的数量，电感和电容器的数量/值/重量/体积，直流总线电压性能（峰-峰电压纹波，过冲和建立时间），总谐波失真（交流侧输入电流和电压的总谐波失真（THD），位移功率因数（DPF），不同负载条件下的功率效率以及交流频率可变操作下的性能。比较表明，通过在系统中增加更多的电容器（电容器的数量和总重量）以及更复杂的控制方案，MMC效率最高，并提供最佳的直流总线性能。 VSC通过较少的无源元件提供了相对较高的效率和直流总线性能，这表明从性能和成本两方面来看，VSC是一个不错的选择。提出了实现集成变速MVDC电源系统的程序来解决问题3）。对于直流发电链，燃气轮机，同步发电机和交流-直流整流器的每个组件，分析了它们的稳态效率和系统效率与直流负载的关系。在10％的负载下，相对系统效率的提高（燃料减少的指标）可以达到35％。当直流负载增加到45％负载时，相对效率提高降低到5％。按照该步骤，开发了变速MVDC电力系统仿真模型。动态响应表明，系统可以跟踪不同负载需求的速度指令，同时获得最高效率和良好的系统稳定性。

著录项

  • 作者

    Li, Dan.;

  • 作者单位

    University of South Carolina.;

  • 授予单位 University of South Carolina.;
  • 学科 Engineering Electronics and Electrical.;Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 108 p.
  • 总页数 108
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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