电子电力变压器的保护系统研究

发布时间：2018-03-31 09:41

本文选题：电子电力变压器　切入点：变压器保护　出处：《华中科技大学》2014年博士论文

【摘要】：对于电力系统而言,电力变压器是最关键的元件之一,起着电力系统关键节点以及交换和传递能量的作用,同时也与电力系统的稳定性和可靠性息息相关。电子电力变压器是一种全新的电力变压器,其原方和副方的电压幅值和相角都可以实现实时控制,因此可以实现对电流和功率的控制。由于电子电力变压器由电力电子变换器组成,因此其相连接的电力系统的可靠性与组成电子电力变压器的电力电子变换器及其开关器件密切相关,使得电子电力变压器的保护系统、故障特征和故障检测尤为重要,其故障可能对整个电力系统造成损失。而国内以及国际上对电子电力变压器的保护系统较少有人研究,而在装置级和器件级的保护上更是几乎一片空白,因此本文主要对配电网电子电力变压器的装置级和器件级保护进行研究和探讨。第一章主要介绍电子电力变压器的研究现状,之后对其适用拓扑以及大致控制策略进行简单阐述。第二章侧重对电子电力变压器保护系统的原理和基本硬件进行研究,其中包括监控保护机箱、各个检测板、控制系统、开关器件硬件保护以及避雷器的设计,提出了电子电力变压器基本保护的策略以及方案。第三章对第二章保护系统中的硬件进行逻辑和算法方面的研究,并按照电子电力变压器的工作状态将保护系统分为数个阶段,并按此分段实施保护。第四章则对前文所设计的保护系统挑选了数个具有代表性的故障进行了测试,表明所研究的电子电力变压器的装置级保护可以实现对电子电力变压器的保护。第五章从电子电力变压器的器件保护出发,通过对电子电力变压器的运行进行分析,推导得出了其开关器件故障后的故障特征,并发现其相关波形的畸变与具体故障开关器件的位置以及故障类型有紧密的联系,由此能够对每个故障的开关器件进行定位。最后通过仿真对故障特征进行了验证,并提出了基于其分析结果的故障定位算法。第六章研究了输入电压的电压跌落以及短时断电对电子电力变压器固有运行方式以及保护方式所造成的影响,指出该故障下电子电力变压器的IGBT将会过电流,并最后通过分析与仿真得出避免和减轻其开关器件过流的措施。第七章讨论了在电子电力变压器上应用混合级联多电平拓扑以及包括阶梯波调制在内的数个调制方法的可能性,并对混合级联多电平拓扑上应用阶梯波调制,PWM调制以及部分PWM调制进行仿真,随后基于谐波和开关损耗对其结果进行比较。最后搭建了15电平逆变器的实验室样机,并实现了近似正弦波且总谐波畸变率低于5%的输出电压。
[Abstract]:For power system, power transformer is one of the most important components, which acts as the key node of power system and functions as the exchange and transfer of energy. At the same time, it is closely related to the stability and reliability of power system. Electronic power transformer is a new kind of power transformer, whose voltage amplitude and phase angle can be controlled in real time. Therefore, the control of current and power can be realized. Because the electronic power transformer is composed of power electronic converter, the reliability of the connected power system is closely related to the power electronic converter and its switching device that make up the electronic power transformer. It makes the protection system of electronic power transformer, fault characteristic and fault detection especially important, and its fault may cause losses to the whole power system. However, there are few researches on the protection system of electronic power transformer at home and abroad. But the protection of device level and device level is almost a blank, so this paper mainly studies and discusses the device level and device level protection of electronic power transformer in distribution network. The first chapter mainly introduces the research status quo of the electronic power transformer, and then gives a brief description of its applicable topology and general control strategy. The second chapter focuses on the principle and basic hardware of the electronic power transformer protection system. These include the monitoring and protection case, the various detection boards, the control system, the switch device hardware protection and the design of the lightning arrester. In chapter 3, the logic and algorithm of the hardware in the second chapter are studied, and the protection system is divided into several stages according to the working state of the electronic power transformer. In the fourth chapter, several representative faults are selected for the protection system designed in the previous chapter. It is shown that the device level protection of the studied electronic power transformer can realize the protection of the electronic power transformer. In the fifth chapter, based on the device protection of the electronic power transformer, through the analysis of the operation of the electronic power transformer, the fault characteristics after the fault of the switch device are deduced. It is also found that the distortion of the relevant waveforms is closely related to the location and type of the fault switch devices, so that each fault switch device can be located. Finally, the fault characteristics are verified by simulation. A fault location algorithm based on its analysis results is proposed. In chapter 6, the influence of voltage drop of input voltage and short time outage on the inherent operation mode and protection mode of electronic power transformer is studied. It is pointed out that the IGBT of electronic power transformer will overcurrent under this fault. Finally, through the analysis and simulation, the measures to avoid and reduce the overcurrent of its switch device are obtained. In chapter 7, the possibility of applying hybrid cascade multilevel topology and several modulation methods, including step wave modulation, to electronic power transformers is discussed. In this paper, the step wave modulation and partial PWM modulation are simulated on the hybrid cascade multilevel topology, and the results are compared based on the harmonic and switching losses. Finally, the laboratory prototype of the 15-level inverter is built. The output voltage with approximate sine wave and total harmonic distortion rate is less than 5%.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM41

【参考文献】