无触点有载调压配电变压器可靠性技术的研究与实现

发布时间：2019-06-21 01:01

【摘要】：具有自动有载调压功能的配电变压器能够有效解决在电力系统无功功率充足的条件下电网末端电压波动的问题,因此无触点有载调压配电变压器已成为配电网自动化研究领域的一个重要方向。国内外专家学者们多年来进行了大量理论研究与实践探索,本课题所在项目前期也已取得突破性进展,研制出以50kVA配电变压器为平台,基于反并联晶闸管模块为分接开关、单片机为控制单元的核心的无触点有载调压装置样机。经实验室模拟试验验证,该样机具备基本调压功能,但在挂网运行试验中为感性负载比重较高的负荷供电时出现了过流保护动作并伴随分接开关被击穿的故障,不能完全可靠工作。因此运行可靠性问题是当前阻碍无触点有载调压配电变压器推广应用的技术关键。本课题所进行的无触点有载调压配电变压器可靠性技术的研究与实现就是以提高运行可靠性为目标,完成相应理论分析与方案的改进。首先从当前无触点有载调压配电变压器的构成、工作原理和以往实验结果着手进行分析,初步确定了六项因素有可能对无触点有载调压配电变压器可靠工作造成影响,其中励磁涌流、过渡支路工作可靠性、反并联晶闸管换向过电压、驱动单元输入输出绝缘能力和单片机程序可靠性将威胁无触点有载调压装置的可靠工作,引发故障。本文分部分针对已确定对运行可靠性产生威胁的因素提出相应改进方案：综合考虑励磁涌流、过渡支路和反并联晶闸管换向过电压三个因素,改进了主电路结构,将启动机构与过渡支路合并,合理设置阻容吸收电路参数并将其模块化以提高对反并联晶闸管换向过电压的吸收能力;利用光纤通信技术在高压电气隔离方面的优势,本文设计了反并联晶闸管光纤触发电路,实现位于配电变压器高压侧的反并联晶闸管与位于低压侧的控制单元之间可靠电气隔离；本文以看门狗芯片为核心,设计出各关键控制信号闭锁电路以防止单片机程序紊乱死机造成分接开关的误动。在测试实验中,控制单元故障闭锁装置能够在单片机模拟复位时保持调压装置的工作状态,并且使单片机重新进入程序后从复位前的工作状态开始继续运行。实验室模拟试验和现场带负荷试验结果表明,改进后的无触点有载调压配电变压器能够实现基本调压功能,并且在空载合闸、感性负荷接入以及突然切除全部负荷这三种特殊情况下依然能够可靠工作。运行可靠性问题的解决使无触点有载调压配电变压器不再仅限于理论分析与样机试验的研究程度,有助于无触点有载调压配电变压器的推广应用。可靠性技术的实现最终能从无触点有载调压的角度促进配电网自动化水平的提高,让电网末端电力用户得到稳定可靠的电能。
[Abstract]:The distribution transformer with automatic on-load voltage regulation function can effectively solve the problem of voltage fluctuation at the end of power network under the condition of sufficient reactive power in power system, so contactless on-load voltage regulating distribution transformer has become an important research direction in the field of distribution network automation. Experts and scholars at home and abroad have carried out a lot of theoretical research and practical exploration for many years, and a breakthrough has been made in the early stage of the project. A prototype of contactless on-load voltage regulating device based on 50kVA distribution transformer as platform, reverse parallel thyristor module as tap changer and single chip microcomputer as the core of control unit has been developed. The laboratory simulation test shows that the prototype has the basic voltage regulating function, but the overcurrent protection action and the breakdown of the tap changer can not work completely when supplying power to the load with high proportion of inductive load in the hanging network operation test. Therefore, the problem of operation reliability is the key to hinder the popularization and application of contactless on-load voltage regulating distribution transformer. In this paper, the research and implementation of the reliability technology of contactless on-load voltage regulating distribution transformer is to improve the operation reliability and complete the corresponding theoretical analysis and scheme improvement. First of all, based on the analysis of the composition, working principle and previous experimental results of the contactless on-load voltage regulating distribution transformer, it is preliminarily determined that six factors may have an impact on the reliable operation of the contactless on-load voltage regulating distribution transformer, including inrush current, the reliability of the transition branch, and the reverse parallel thyristor switching overvoltage. The input and output insulation ability of the driving unit and the reliability of the single chip microcomputer program will threaten the reliable operation of the contactless on-load voltage regulator and cause faults. In this paper, the corresponding improvement scheme is put forward according to the factors that threaten the operation reliability: considering the three factors of inrush current, transition branch and reverse parallel thyristor commutation overvoltage, the main circuit structure is improved, the starting mechanism and transition branch are combined, and the parameters of resistance-capacitance absorption circuit are reasonably set and modularized to improve the absorption capacity of reverse parallel thyristor switching overvoltage; Based on the advantages of optical fiber communication technology in high voltage electrical isolation, this paper designs an inverse parallel thyristor fiber trigger circuit to realize reliable electrical isolation between the reverse parallel thyristor located on the high voltage side of the distribution transformer and the control unit on the low voltage side. In this paper, based on the watchdog chip, the locking circuit of each key control signal is designed to prevent the misoperation of the tap changer caused by the disorder of the single chip microcomputer program. In the test experiment, the fault locking device of the control unit can maintain the working state of the voltage regulating device when the single chip microcomputer simulates reset, and make the single chip microcomputer continue to run from the working state before reset after re-entering the program. The results of laboratory simulation test and field load test show that the improved contactless on-load voltage regulating distribution transformer can realize the basic voltage regulation function, and can still work reliably under the three special conditions of no-load closing, inductive load access and sudden removal of all loads. The solution of operation reliability makes the contactless on-load voltage regulating distribution transformer no longer limited to the research degree of theoretical analysis and prototype test, which is helpful to the popularization and application of contactless on-load voltage regulating distribution transformer. The realization of reliability technology can finally promote the improvement of distribution network automation level from the point of view of contactless on-load voltage regulation, so that the power users at the end of the power grid can get stable and reliable electric energy.
【学位授予单位】：东北农业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM421

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