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某500 kV变电站利用SF 6断路器投切35 kV并联电容器组时,连续发生2起串联电抗器设备故障,分析原因是在投切操作过程产生了较大的涌流及过电压,引起干式空心电抗器发生匝间短路故障,严重威胁系统的安全运行。为了避免此类故障的再次发生,提出采用适用于投切35 kV并联电容器组的智能相控断路器来抑制合闸涌流,降低分闸重燃概率。为验证智能相控断路器的有效性,首先分析了投切涌流及过电压产生的原因和相控开关技术的原理,然后将智能相控断路器应用于该500 kV变电站的35 kV无功补偿系统,并分别对智能断路器与普通断路器进行多次分合闸对比试验,试验结果表明:普通断路器随机投切电容器组产生的最大涌流为4.2(标幺值,下同),过电压为1.81;智能相控断路器投切电容器组产生的最大涌流为2.3,过电压为1.4。试验结果证实智能相控断路器的应用能够从源头抑制合闸涌流和过电压,提高无功投切效率和系统安全性。 相似文献
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设计了一种用于升压式DC-DC开关电源的新型软启动电路。该电路结构简单、稳定性强、易于集成、功耗较低,不仅能有效地抑制DC-DC开关电源在启动时产生的浪涌电流,而且能避免电压过冲现象,保证输出电流上升的稳定性和可靠性。该电路采用0.5μm CMOS工艺进行设计,已成功集成到一款升压式DC-DC开关电源芯片内。测试结果表明,在输入电压为3.6 V,输出电流为100 mA的工作状态下,输出电流分四段台阶平稳上升、无电压过冲现象,启动时间控制在140μs以内。 相似文献
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Yoshiki Nakachi Takayuki Fukae Toshinori Sugahara Hayato Nakamura Mitsuaki Koyama Fukashi Ueda 《Electrical Engineering in Japan》2013,185(1):36-47
It is well known that a voltage drop due to inrush current at an energizing transformer may at times interrupt electrical equipment. Generally, the voltage drop is calculated by using a sophisticated tool such as EMTP, so that the transformer saturation phenomenon has been properly represented. However, it is not practical for distribution system engineers to calculate the voltage drop with transformer inrush by using EMTP, because there are many network access requests needing such calculations with many kinds of transformers. Therefore, in this paper, a simplified and easy‐to‐use calculation tool for voltage drops caused by transformer inrush in a distribution system is developed. In order to understand the voltage drop by inrush current during the planning stage, it is formulated by considering the transformer saturation/unsaturation periods in each winding type. The newly developed tool is based on versatile spreadsheet software such as Microsoft Excel ýO.R. It can be used with accuracy similar to that of EMTP. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 185(1): 36–47, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22394 相似文献
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基于小波理论和多分辨分析的变压器励磁涌流识别方法 总被引:1,自引:1,他引:0
提出一种基于小波变换和多分辨分析识别变压器励磁涌流和内部故障电流的新方法。根据故障初始阶段励磁涌流的高频分量随时间推移逐渐变大而故障电流高频分量逐渐变小的特点,首先用Daub-4小波对励磁涌流和故障电流进行分解,得到第1层小波系数的2个初始峰值点,然后通过引入可靠性系数来识别励磁涌流和故障电流。动模试验结果表明,该方法能够可靠快速地识别励磁涌流和故障电流,且不需要考虑保护的整定值,实现方便。 相似文献
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变压器铁芯饱和统一模型建立及其判别方法 总被引:2,自引:0,他引:2
建立了变压器铁芯饱和的统一模型,推导出磁链最大值与电压突变时刻、突变前后电压相角差及突变后电压幅值的关系式,铁芯是否饱和与这些参数密切相关。发现电压降低(如系统发生故障或者非同期合闸操作)情况下也会产生铁芯饱和,因而以电压幅值降低作为变压器不会产生励磁涌流的依据并不可靠。进而提出一种基于电压量积分的铁芯饱和判别方法,该方法对空载合闸、故障切除、和应涌流、系统故障或操作等电压突变引起变压器铁芯饱和而产生励磁涌流,都能在半个周期左右的时间完成判别,为差动保护不经涌流闭锁提供了一种有效、快速的实现方法,可显著提高运行变压器发生内部故障时差动保护的动作速度。 相似文献
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Hiroaki Yamada Toshihiko Tanaka Shigeyuki Funabiki 《Electrical Engineering in Japan》2006,157(4):56-65
This paper proposes a novel method of suppressing the inrush current of transformers. A small‐rated voltage‐source PWM converter is connected in series to the transformers through a matching transformer. As the connected PWM converter serves as a resistor for the source current, no inrush phenomena occurs. The required rating of the PWM converter, which serves as the damping resistor for the inrush phenomena, is 1/400 that of the main transformers in single‐phase circuits. In three‐phase circuits, it is 1/900. The basic principle of the proposed method is discussed. Digital computer simulation is implemented to confirm the validity and excellent practicability of the proposed method using the PSCAD/EMTDC. A prototype experimental model is constructed and tested. The experimental results demonstrate that the proposed method can perfectly suppress the inrush phenomena. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(4): 56–65, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20174 相似文献
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一种直接消除变压器合闸励磁涌流的方法 总被引:3,自引:0,他引:3
变压器在轻载或者空载的情况下合闸通电,可能导致一次绕组流过励磁涌流。涌流出现的原因在于变压器铁心因合闸角、剩磁等各种条件的综合作用而进入饱和区甚至是深度饱和区。励磁涌流对变压器自身和电网的电能质量都有不利影响,本文提出了一种基于二阶欠阻尼电路和分压器组成的涌流抑制器,来消除变压器合闸时刻出现的励磁涌流。利用三卷变压器的第三绕组,配以"涌流抑制器"来实现施加在三卷变压器的第三绕组上的电压幅值逐渐爬升,同时保证施加在两个绕组上的电压幅值不同、但相位相同,以起到对励磁涌流的抑制作用。仿真结果证实了该方法的正确性和有效性。 相似文献
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Many transformers may be connected in parallel to a distribution busbar to supply the load. Restoration of power supply after a black-out is carried out by switching on the transformers one by one, producing high inrush current at the instant of switching of each transformer. It is proposed that circuit breakers connected to all transformer secondaries should be closed first. Then, closing the primary side circuit breaker of the first transformer also energizes all remaining transformers from the secondary side. Inrush current in the first transformer with closed secondary circuit breakers of all transformers does not increase to a very high value. No inrush current is produced during subsequent switching of any other transformer from the primary side, as they are already energized from the secondary side. 相似文献
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利用数学形态学提取暂态量的变压器保护新原理 总被引:13,自引:6,他引:13
提出了一种识别变压器励磁涌流和短路电流的新方法,该方法在利用数学形态梯度进行边沿检测的同时, 采用形态开闭运算有效地提取出高频暂态电流信号。在比较励磁涌流和故障电流形成暂态信号各自特点的基础上,提出了一种变压器保护新方案。该方案不受对称性涌流的影响,并且可对暂态信号进行实时、高精度的提取。动模试验仿真结果验证了该方案的可行性。同时,该算法的计算量较多尺度小波变换计算量小,有利于工程实现。 相似文献
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结合近几年来南方电网多次出现的变压器空投涌流引起直流50 Hz保护动作事件,仿真研究了励磁涌流、和应涌流及故障电流波形特征差异性,在不降低保护灵敏度的原则下,提出了一种基于波形识别的直流50Hz保护优化改进策略,并在高压直流PSCAD/EMTDC控制保护仿真模型的基础上结合优化改进策略自定义创建直流50Hz保护闭锁模型,从交流系统强度变化、换流变压器空载合闸角变化、换流变压器铁芯剩磁变化三个角度对所提出的优化策略进行仿真验证。结果表明,所提出的基于波形识别的直流50Hz保护优化改进策略能正确地实现直流50 Hz保护的闭锁和解锁,在不影响直流系统安全稳定运行的情况下很好地解决了变压器空投涌流引起直流50Hz保护误动的问题。 相似文献
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应用模糊贴近度原理识别励磁涌流的新方法 总被引:1,自引:1,他引:0
为提高我国220kV及以上变压器保护正确动作率,提出了一种基于模糊贴近度原理的识别变压器励磁涌流的新方法。该方法通过比较归一化后前后半周期波形的贴近程度来区分励磁涌流和故障电流:励磁涌流的波形畸变严重,在波形上以间断角和波形不对称的形式出现,因此归一化后前后半波贴近程度低,接近于0;而内部故障电流波形含有较少的2次谐波和高次谐波分量,在波形上以对称的形式出现,前后半波贴近程度高,接近于1。同时,应用模糊数学工具将该原理的3种类型相结合以使其优势互补。理论分析和动模实验结果表明:该方法原理简单、易于实现,可准确识别故障电流和励磁涌流,即使空载合闸于内部短路故障时保护也能迅速可靠动作。 相似文献
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为解决智能变电站复杂数字采样回路环节引起的采样数据异常,提出一种新模式的常规采样GOOSE跳闸变压器保护设计方法。利用NPI插件实现模拟量双AD直接采样的新采样回路并兼容GOOSE信息传输,同时配合基于滑动数据窗的双AD实时采样数据互校验判据,用于监测采样数据的有效性。另外,针对特高压变压器涌流特性,提出了一种分相差流谐波或闭锁、非间断点开放的综合励磁涌流识别判据。仿真结果表明,综合励磁涌流识别判据可以应用于新模式的变压器保护。 相似文献
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一起特高压变压器的差动保护误动分析及防范措施 总被引:3,自引:0,他引:3
通过建立MATLAB仿真模型,分析了在特高压交流试验示范工程投运调试过程中出现的一起由于中压侧空投主变压器产生励磁涌流而导致调压变压器差动保护误动作的案例。针对特高压变压器结构上的特殊性,分析了合闸角、剩磁等因素对励磁涌流的影响,仿真复现了现场故障录波波形。针对调压变压器差动电流中二次谐波含量较低可能引起的误动,从2个方面提出了相应的解决方案:指出二次谐波涌流闭锁判据宜采用三取二闭锁方式,但在某些特殊情况下,依然可能失效,进而提出了利用二次谐波变化趋势来识别励磁涌流和故障电流的辅助判据,并对综合判据进行了仿真验证;分析了调压变压器容量对励磁涌流的影响,提出在条件允许的情况下,适当增加调压变压器容量来避免励磁涌流可能引起的误动,为提高调压变压器差动保护可靠性提供了新思路。 相似文献
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《IEEJ Transactions on Electrical and Electronic Engineering》2017,12(6):834-840
Converter protection, including bridge differential protection and valve short‐circuit protection, frequently malfunctions during the disturbance from an AC system, such as the short‐circuit fault and the inrush current, which severely threatens the safe and stable operation of an AC/DC hybrid power system. This paper analyzes the cause of such maloperation based on mechanism analysis and simulation tests. It is found that saturation of the current transformer in the delta winding of the YD converter transformer during the disturbance of the AC system is the main reason for this sort of maloperation. To solve this problem, this paper proposes a countermeasure by introducing the zero‐sequence circulating current as the restraint current of the bridge differential protection. The time difference between the increase of the zero‐sequence circulating current and the rise of the bridge differential current is utilized to determine whether to apply the proposed countermeasure. Simulation tests indicate that this countermeasure can improve the reliability of the bridge differential protection during the disturbance in the AC system, without affecting the sensitivity and operation speed of the bridge differential protection for the internal fault. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献