【作者】 赵越；

【导师】 王广柱；

【作者基本信息】 山东大学 ， 电气工程， 2021， 硕士

【摘要】 随着现代社会的高速发展,供电质量与谐波等问题的矛盾日益尖锐,配电网瞬时故障造成了大量的经济损失。电能质量问题主要集中在两个方面,电流相关的谐波与无功方面和电压相关的跌落与谐波方面。传统的电能治理设备,像APF与DVR只能解决单一电流或者电压问题。统一电能质量控制器(UPQC)将APF与DVR有机结合,形成统一整体,从而实现一个设备同时解决电流与电压相关的问题。传统UPQC能够通过容量选择,解决不同情况下的问题。但是由于其本身串并联侧耦合,控制相对复杂,难以有效解决大幅度电压跌落问题。为此,本文采用了一种新型“APF+DVR”型UPQC,能够克服传统UPQC的不足。新型UPQC拓扑由两个独立并联电压源型变换器(VSC)组成,分别实现APF和DVR功能。提出了 APF与DVR投切策略,针对DVR控制,提出基于DVR直流侧电压的分段式控制方法,给出了 DVR直流侧电容器容量计算方法。仿真结果表明,新型UPQC可实现串并联侧硬件解耦、独立控制,静态损耗低,响应速度快,不受电压暂降水平影响,可有效解决大幅度电压跌落问题。本文主要研究内容如下:(1)介绍新型“APF+DVR”型UPQC的拓扑结构和工作原理。介绍APF侧拓扑和工作原理、DVR侧拓扑和工作原理、高速固态开关工作原理以及Z型变压器组别和工作原理。对APF的二极管钳位式三电平电路和DVR的三相桥式电路进行了建模。(2)介绍新型“APF+DVR”型UPQC的主电路设计。介绍DVR作为逆变器时与普通逆变器的不同,并对其直流侧电容选择进行了详细介绍,提出基于能量守恒的电容选择方法。介绍APF直流侧的电容选择方法与无源滤波器设计方法。(3)对新型“APF+DVR”型UPQC控制策略进行了详细介绍。介绍网侧电压电流异常检测方法,包括单相电压跌落检测、电压谐波检测和电流有效值计算三个部分。介绍整个新型UPQC的投切逻辑,着重介绍DVR投入时可能出现的问题以及应对方法。介绍新型UPQC的控制方式,着重介绍DVR的控制方式,提出分段式电压控制方法。(4)在实时仿真实验平台RT-LAB对新型“APF+DVR”型UPQC进行了仿真分析。介绍仿真参数,并对仿真模型做出了详尽的介绍。对APF和DVR分别进行仿真,其中DVR部分涉及电压瞬时跌落、电压谐波和大幅度电压跌落。最后对比了新型UPQC和传统UPQC在同样工况下的补偿能力。(5)提出了新型“APF+DVR”型UPQC的改进拓扑单电压源变换器统一电能质量控制器,并分析了改进拓扑相对于前者的优缺点。分析了 SVSC-UPQC的工作原理和控制策略,并对相关内容进行的仿真验证。更多还原

【Abstract】 With the modern society rapidly developing,the contradiction between power quality and problems like harmonic has become more serious.The failure of distribution network could cause huge amount of economic loss.There are two aspects of power quality problems,harmonic and reactive power problems to do with current and instant drop problems to do with voltage.Those traditional power quality compensation equipment,such as APF and DVR,could only deal with one aspect by their own.The Unified Power Quality Conditioner(UPQC)combined APF and DVR to one unit,to solve both current and voltage problems at the same time.The traditional UPQC could deal with different situation by choosing capacitance wisely;however,due to the coupling between serial and parallel section,the control method is relative difficult and it could not solve large voltage drop problem.This paper proposed a new type of "APF+DVR" UPQC to overcome the shortcomings of traditional UPQC.The topology of the new type of UPQC is consist of two independent voltage source converters,implementing the functions of APF and DVR seperately.The switching logic is proposed for the APF and DVR sections,and for the DVR section,a segmented control method based on the voltage of DC side,along with the capacitance calculation method for the DC side are given.Simulation results indicate that the new type of UPQC could realise hardware decoupling and be independently controlled.Besides,the static loss is low and the responding speed is high,and with no affection with voltage drop level,the large voltage drop problem could be solved.The following contents show the main research of the paper:(1)Introducing the topology and working principle.Introducing the topologies of APF and DVR section,high-speed solid-state switch and zig-zag transformer.Giving the mathematic model of the diode-clamped three-level converter and three-phase bridge converter.(2)Introducing the design of the main circuit.Introducing the difference between normal inverter and DVR working as a inverter.Introducing the capacitance selective method of the DC side in detail and proposing a capacitor choosing method based on power conservation.Introducing the capacitor selective method for the APF side and design of the LC filter.(3)Introducing the control strategy for the new type of UPQC.Introducing the detection methods for the grid problems,including single-phase voltage drop,voltage harmonic and RMS of the current.Introducing the switching logic for the new type of UPQC as a whole,concentrating on the problems may happen when the DVR is activated and ways to deal with the problems.Introducing the control method for the new type of UPQC,focusing on DVR,and proposed a segmented voltage control method.(4)In the realtime simulation platform,RT-LAB,simulation was built for the new type of UPQC with the parameters and model introduced in detail.APF and DVR are simulated seperately,and for the DVR section,simulation about instant voltage drop,voltage harmonic and large voltage drop are included.At last,compared the compensation capability between the new type of UPQC and traditional UPQC at the same situation.(5)Proposed an improved topology of the new type of UPQC,called the Single Voltage Source Converter-UPQC(SVSC-UPQC),and analyzed the pros and cons of the topology.Introducing the working principle and control strategy of the SVSC-UPQC,and simulated related contents.更多还原