【作者】 刘巍；

【导师】 赵剑锋；

【作者基本信息】 东南大学 ， 电气工程， 2015， 硕士

【摘要】 近年来,随着新能源与分布式发电的兴起以及智能电网这一概念的提出,电力电子变压器将在电力系统中发挥日益重要的作用。目前电力电子装置广泛应用于航空航天器及各种工业设备,其可靠性问题已成为保障航天器或工业设备安全运行的一项关键技术。电力电子变压器作为一种电力电子装置,其故障检测技术与容错控制技术具有重要的理论与现实意义。本文首先对电力电子变压器的发展与原理作出介绍,并对电力电子装置的故障检测与容错控制进行了概括与综述,并提出了一种典型级联型电力电子变压器结构。针对此结构,首先对输入级、中间级、输出级分别建立了数学模型,并在数学模型的基础上研究了各级典型的控制策略。其次,本文针对级联型电力电子变压器的输入级、中间级、输出级分别研究了相应的故障检测方法与容错控制方法。在故障检测技术方面,输入级分别采用基于开关谐波分析的方法与基于脉冲电压比较的方法,两种方法都是以H桥单元为检测单位；输出级采用一种基于Park变换与神经网络的故障检测方法,通过对三相输出电流的处理与分析确定故障类型。在容错控制技术方面,输入级一个H桥单元与中间级一个DAB单元作为一个容错单元,并采用结合直流侧优化的双零序电压注入法进行容错控制,通过注入零序电压实现各相功率的重新分配；输出级采用三相四开关的容错重构结构,通过七段式SVPWM调制实现容错运行。本文通过MATLAB/Simulink平台建立了级联型电力电子变压器模型,对文中研究的级联型电力电子变压器控制策略的仿真验证了其工作性能。文中提出的各故障检测方法与容错控制方法也均通过仿真进行了验证,输入级及输出级的软件故障检测方法均可用于在线故障检测,各级的容错控制策略也证明了其正确性及可行性。更多还原

【Abstract】 Recently, with the rise of new energy and distributed power generation, and with the proposition of the concept of smart grid, power electronic transformer (PET) will play an increasingly important role in power system. At present, the power electronic devices are widely used in the field of aerospace and industrial equipments. The reliability of power electronic devices has become a key technology to guarantee the safe running of spacecrafts and industrial equipment. As a power electronic device, fault detection technology and fault-tolerrence control of PET are highly significant both in theory and practice.Firstly, introduction is made about the development and principle of PET. Summary of fault detection and fault-to lerrence control technology for power electronic devices is given afterwards. This article issues a structure of cascaded PET and divides it into three stages namely the input stage, the intermediate stage, and the output stage. Mathematical models of the three stages are made. Furthermore, control strategies are studied for each stage, with verification via simulation. Secondly, for the three stages of the cascade PET corresponding fault detection method and fault-tolerant control methods are investigated. In the aspects of fault detection, two methods are studied for the input stage. One method is based on analysis of s witching frequency harmonics and the other is based on pulse voltage comparasion. Both methods take the H-bridge unit as the detection unit. A method based on Park transformation and neural network is applied to the output stage, by way of analyzing three-phase output current. All methods for fault detection are verified by simulation. In the aspects of fault-tolerant control, with a fault-tolerant unit containing an H-bridge unit of input stage and a DAB unit of intermediate stage, this article proposes a fault-tolerant control strategy based on double zero-sequence voltage injection and DC voltage optimization. Zero-sequence voltage injection leads to power redistribution of each phase. The output stage applies a three-phase four-switch fault tolerant reconfigurable architecture to achieve fault-tolerant operation through the seven-segment SVPWM modulation.MATLAB/Simulink platform of a cascaded PET is established. Simulation of the control strategies presented in this paper verifies the performance of the cascaded PET. Fault detection methods and fault-to lerrence control methods presented in the paper are also verified by way of simulation. The software fault detection methods of input stage and output stage can be used for online fault detection. Fault-tolerance control strategies of all stages have proved the correctness and feasibility.更多还原