级联H桥型SVG控制策略的研究及其链节单元测试系统的设计

发布时间：2018-05-06 01:22

本文选题：静止无功发生器 + 级联　；参考：《北京交通大学》2014年硕士论文

【摘要】：随着电力电子技术的发展,电力电子开关器件得到广泛的应用。电网中随之出现了大量的非线性负载,无功需求也越来越大。静止无功发生器(SVG)作为新生代的无功补偿装置,具有响应速度快、损耗低、储能元件体积小和输出电流谐波含量低等优点,可以有效地补偿无功。近些年,无功补偿装置朝着功能综合、高压大容量等方向发展。增加多种工作模式也可以使SVG实现多种功能。级联是设计高压大容量无功补偿装置的一个重要方法。本文以国家电网智能电网研究院中电普瑞科技有限公司,"10kV/7.2Mvar级联H桥型SVG的研制”这一项目为依托,研究级联H桥型SVG的控制策略,优化其链节单元生产过程中的测试。本文设计的级联H桥型SVG的控制策略主要包括电流工作模式(实现无功补偿)和电压工作模式(实现防止电压跌落)两大部分。电流工作模式中的重点是有功电流无功电流的解耦控制、直流电压的三级平衡控制。常见的级联H桥型SVG只具有无功补偿一个功能。但是电网在实际的运行过程中,还会遇见电压跌落的问题。如果再设计一个装置防止电压跌落,必然会加大成本。本文设计的级联H桥型SVG,添加了一个电压工作模式,使SVG兼有无功补偿和防止电压跌落两个功能,有效地解决了这个问题。常见的SVG数学模型中,有功电流、无功电流是相互耦合的,这加大了控制的难度。本文针对这个问题,将有功电流无功电流解耦,分别控制,简化的控制策略,收到了很好的效果。级联H桥型SVG中,直流电容相互独立。这虽然简化主电路,使其省去了移相变压器和整流电路,但同时也带来了电容电压的平衡控制问题。本文,针对这一问题,设计了直流电压的三级平衡控制的方法,使直流电压能够维持到期望值。本文在MATLAB/SIMULINK仿真模型和实验平台上,进行了仿真及实验验证。结果表明,SVG系统的防止电压跌落功能良好,无功补偿功能效果好和动态响应快。最后,针对级联H桥型SVG生产过程中链节单元测试实验复杂的问题,本文研制了链节单元的测试系统,方便了实验操作,提升了工作效率。
[Abstract]:With the development of power electronics technology, power electronic switch devices are widely used. With the emergence of a large number of nonlinear loads in the power grid, reactive power demand is also increasing. Static Var Generator (SVG), as a new generation of reactive power compensation device, has the advantages of fast response speed, low loss, small volume of energy storage element and low harmonic content of output current, which can effectively compensate reactive power. In recent years, reactive power compensator is developing towards function synthesis, high voltage and large capacity. Adding a variety of working modes can also enable SVG to achieve a variety of functions. Cascade is an important method to design high voltage and large capacity reactive power compensator. In this paper, the control strategy of cascaded H-bridge SVG is studied based on the project of "10kV/7.2Mvar cascaded H-bridge SVG" in China Electric Power Plant Technology Co., Ltd., the State Grid Research Institute of Smart Grid, and the testing in the production process of the chain segment unit is optimized. The control strategy of cascaded H-bridge SVG designed in this paper includes two parts: current mode (reactive power compensation) and voltage mode (to prevent voltage drop). The emphasis of current mode is decoupling control of active current and reactive current, and three-stage balance control of DC voltage. The common cascaded H-bridge SVG has only one function of reactive power compensation. However, in the actual operation of the grid, it will also meet the problem of voltage drop. If a new device is designed to prevent the voltage from falling, it will inevitably increase the cost. In this paper, a voltage mode is added to the cascaded H-bridge SVG, which makes the SVG have two functions, reactive power compensation and voltage drop prevention, which can effectively solve this problem. In the common SVG mathematical model, active current and reactive current are coupled with each other, which increases the difficulty of control. In order to solve this problem, the active current and reactive current are decoupled, controlled separately and simplified, and good results are obtained. In cascaded H bridge SVG, DC capacitors are independent of each other. Although this simplifies the main circuit and saves the phase-shift transformer and rectifier circuit, it also brings about the problem of capacitor voltage balance control. In this paper, a three-stage balance control method of DC voltage is designed to maintain the DC voltage to the expected value. In this paper, the MATLAB/SIMULINK simulation model and experimental platform, simulation and experimental verification. The results show that SVG system has good function of preventing voltage drop, good effect of reactive power compensation and fast dynamic response. Finally, in order to solve the complex problem of chain node unit test in the production of cascaded H-bridge SVG, a chain unit testing system is developed in this paper, which facilitates the operation of the experiment and improves the working efficiency.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM761

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