【作者】 董恩源；

【导师】 邹积岩；

【作者基本信息】 大连理工大学 ， 机械电子工程， 2004， 博士

【摘要】 近年来,直流电力系统在世界各国得到了普遍发展,尤其在城市轻轨、地铁以及船舶等处应用更多。传统的高压直流输电工程都是二终端的传输方式,系统一般通过换流器或逆变器的控制便可消除故障电流,或者在交流侧分断故障电流。为了增加直流输电的灵活性,人们希望采用多终端的直流输电系统,直流断路器成为直流电力系统的“瓶颈”问题。 为了实现直流的短路开断,本文采用电流转移原理,提出了断路器的新型结构,即应用一个机构同步操作连在一个杠杆上的两个真空灭弧室,实现了主电路分闸与转移电流投入的同步操作,不但动作迅速、工作可靠,同时满足了在要求的开距下投入转移电流,投入时间精确。为直流电力系统的进一步发展提供了一个新的解决方案。 本研究的电流转移是在主、次两个灭弧室中完成的。在主灭弧室上并联一个由预充电的电容器和电感组成的电流转移回路,当线路中发生故障时,主灭弧室分断,同时,次灭弧室关合,使转移回路接入系统中,在电容器、电感与主灭弧室电弧间形成振荡电流。此电流叠加到故障电流上,强迫其过零,从而为主灭弧室提供良好的开断机会。本文把电流转移过程分为三个阶段:1.短路故障发生,主灭弧室分闸;2.次灭弧室关合,转移电流投入,并强迫故障电流过零;3.过零后,主灭弧室中电弧熄灭,系统对转移电容充电。给出了每个阶段的数学表达式,分别对它们进行了电路仿真,并对仿真结果进行了分析。对线路电感对电容残压值的影响进行了分析,并提出了快速开断剩余电流的方法。 在直流真空断路器系统设计中,本文首先提出了电子操动的概念,并以永磁操动机构为例分析了电子操动的精度和可靠度。直流真空断路器的控制和故障数据的采集、判断是由单片机智能测控系统来完成的,采用电流瞬时值(△I)和电流变化率(di/dt)相结合进行比较的办法,判断出故障的发生,并输出指令对断路器进行精确地控制。 针对直流断路器的特殊需求,本文对两种快速操动机构进行了磁场分析和设计。对永磁机构的工作过程进行了动态分析并对其进行了数学建模,给出了状态微分方程组的求解,应用四阶龙格库塔法进行了仿真计算,并与实验结果进行了对比,表明仿真计算是可信的,可以指导永磁机构的设计。同时,应用电弧模型进行了转移过程中的最佳开距分析和触头最低初分速度设计。 最后,本研究利用LC振荡回路模拟直流短路故障,对新型直流断路器样机进行了开断实验,最大实验电流达到20kA。从实验结果可以看出,应用电流转移原理的直流断路器,首先要保证分断时间与投入反电流的时间配合精确;其次,要保大连理工大学博士学位论文基于电子操动的快速直流断路器的研究证在分断时,转移电流足够大,使得电弧电流充分过零,可增加转移回路电容器的充电电压值或增加电容量,以保证一定的冗余系数(K习.5)。关键词:直流输电新型直流断路器电流转移原理最佳开距电子操动 永磁机构涡流斥力机构智能测控系统更多还原

【Abstract】 DC power systems are developed in many countries of the world, which are applied widely in trolleybuses、 ships and subways, etc.. Traditional DC transmission system works always by one terminal to the other, and the protection of short faults is depended on controlling converters and inverters or opening system by AC circuit breakers(CB) in AC side. For the sake of improving the flexibility of DC transmission systems, multi-terminal systems are expected to be adopted, and DC-CB becomes a "bottle-neck" in power system.In order to break short faults, the commutation principle is used and a novel structure DC-CB with permanent magnetic actuator (PMA) is introduced, which puts two vacuum interrupters on each end of a rod with a fixed-point in the middle of it. In this way, we can realize the CB’s opening and the current’s transferring synthetically, make sure the moving electrode has reached safe distance to withstand the recovery voltage. It presents a new scheme for the further development of DC power system.The commutation principle’s realizing is finished by two vacuum interrupters. A transfer loop is paralleled to main interrupter, which consists of a pre-energizing capacitance and an inductance. When the fault appears, the main interrupter (in main line) opens and the sub-interrupter closes at the same time. So the oscillatory current is brought in the capacitance, inductance and arc of main interrupter. The oscillatory current is added to the short current, which forces the current in main interrupter to zero, so the opportunity of extinguishing arc appears. Current commutation can be divided into three stages: 1.short fault happens, and main interrupter opens; 2.sub-interrupter closes, and transfer current is devoted, which forces current to zero; 3.after zero, the arc in main interrupter is extinguished, and the capacitance is energized by system. Mathematics expressions of the three stages above are given and simulated. The influence of system inductance to capacitance voltage is analyzed, and the method of fast opening odd current is given in the paper.Electronic-driven system is put forward firstly in design of DC-CB, and the PMA is used to analyze the precision and reliability of electronic-driven. Single-chip micro-computer is used to perform sampling, judging, and △I and di/dt are used to estimate whether fault has happened, then the electronic-driven system will output orders to control CB based on estimation result.Two kinds of fast actuators are analyzed in their magnetic fields. Dynamic analysis and design is done based on the mathematic modules set in the paper. The state equation group is solutioned by means of Runge-kutta method. Compared with the experiment, the simulation result is credible, and it can guide the design of PMA. At the same time, the optimal electrode distance and the lowest prime move-velocity of contact are analyzed in the paper.Finally, breaking experiments of the sample DC-CB’ are done on LC oscillatory circuit in our lab, and the largest test current reaches 20 kA. From the experiment results we know that, for the sake ofusing DC-CB with commutation principle, the main interrupter’s opening and transfer current’s devoting must be cooperated precisely; At the same time, the transfer current must be big enough to force fault current to zero for DC-CB’s reliable work (redundancy rate K>1.5). To satisfy it, the measures of enhancing capacitance energizing voltage level or enlarge actual capacitance should be done in the scheme.更多还原