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1.
电网结构日趋复杂,系统短路容量急剧增加,研究故障情况下提高电压稳定性对于系统安全运行具有重要意义,固态限流器在系统正常运行条件下对外不呈现阻抗,当系统发生短路故障时迅速串入系统网络中。对母线电压具有强支撑作用,利用耦合式三相固态限流器,对2种典型电网系统模型发生故障情况进行了仿真分析。研究表明:固态故障限流器的应用能够有教抑制短路故障引发的系统瞬间电压跌落,而且随着限流阻抗值的增大,相应的改善效果更为明显。这也显示改善系统故障电压是故障限流器具有的一种本质能力。 相似文献
2.
电流转移过程是电阻型故障限流器中的关键问题。针对基于真空开关与电阻并联的限流器中电流由真空电弧电流向并联限流电阻的转移特性进行研究。搭建了基于真空开关与限流电阻并联的试验研究平台,采用高速CMOS相机拍摄电弧,观测真空电弧转移过程中电弧发展变化。通过研究电流大小(5~15 k A)、限流电阻大小(10~4500 mΩ)、燃弧时间、电流频率等对电流转移时间、转移完成时刻电流等的影响,获得了电流转移特性的数学描述。讨论了横向磁场对电流转移特性的影响,为电阻型故障限流器的结构及优化奠定了基础。 相似文献
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A voltage sag compensating using a micro‐SMES is presented. Based on previous works, we have carried out experiments for voltage sag compensation on the laboratory‐built system in order to validate the proposed minimum energy injection voltage sag compensation algorithm. To improve the compensating performance of the system, two‐degree‐of‐freedom voltage control is proposed. In this paper, the circuit configuration and feedback voltage control system of the compensator are described and the experimental results are reported. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(2): 84–92, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10267 相似文献
5.
Bor‐Ren Lin Chih‐Yuan Cheng 《International Journal of Circuit Theory and Applications》2013,41(1):45-58
This paper presents a parallel zero‐voltage switching (ZVS) DC–DC converter with series‐connected transformers. In order to increase output power, two transformers connected in series are used in the proposed converter. Two buck‐type converters connected in parallel have the same switching devices. The primary windings of series‐connected transformers can achieve the balanced secondary winding currents. The current doubler rectifiers with ripple current cancellation are connected in parallel at the output side to reduce the current stress of the secondary winding. Thus, the current ripple on the output capacitor is reduced, and the size of the output choke and output capacitor are reduced. Only two switches are used in the proposed circuit instead of four switches in the conventional parallel ZVS converter to achieve ZVS and output current sharing. Therefore, the proposed converter has less power switches. The ZVS turn‐on is implemented during the commutation stage of two complementary switches such that the switching losses and thermal stresses on the semiconductors are reduced. Experimental results for a 528‐W (48 V/11 A) prototype are presented to prove the theoretical analysis and circuit performance. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
6.
Masaki Yamada Akihiro Suzuki Akihiko Iwata Toshiyuki Kikunaga Hajimu Yoshiyasu Kazuo Yamamoto Nobuhiko Hatano 《Electrical Engineering in Japan》2006,154(3):65-72
This paper presents a new concept for a voltage transient sag compensator and the experimental result of its 400‐V‐class compensator. This compensator is composed of the series connection of some inverter units with gradational output voltages. Because each output voltage is different by 2n times, an approximate sinusoidal voltage is generated by controlling operation of each inverter and compensates voltage sag of the power line. The compensator can be directly installed in a power line without an insertion transformer and a large filter, and thus it is expected to be a compact and economical system. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 154(3): 65–72, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20289 相似文献
7.
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
8.
Shahid Iqbal M. Imran Shahzad 《IEEJ Transactions on Electrical and Electronic Engineering》2015,10(2):229-236
This paper proposes a zero‐voltage switching (ZVS) LLC resonant step up DC–DC converter with series‐connected primary windings of the transformer. The series resonant inverter in the proposed topology has two power switches (MOSFETs), two resonant capacitors, two resonant inductors, and only one transformer with center‐tapped primary windings. The power switches are connected in the form of a half‐bridge network. Resonant capacitors and inductors along with the primary windings of the transformer form two series resonant circuits. The series resonant circuits are fed alternately by operating the power switches with an interleaved half switching cycle. The secondary winding of transformer is connected to a bridge rectifier circuit to rectify the output voltage. The converter operates within a narrow frequency range below the resonance frequency to achieve ZVS, and its output power is regulated by pulse frequency modulation. The converter has lower conduction and switching losses and therefore higher efficiency. The experimental results of a 500‐W prototype of proposed converter are presented. The results confirm the good operation and performance of the converter. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
9.
Yuki Takahashi Ryuji Iijima Takanori Isobe Hiroshi Tadano Choji Yamazaki Chihiro Hasegawa 《Electrical Engineering in Japan》2019,206(3):40-50
This paper proposes a new configuration of a pulse voltage generator, which can be applied to the klystron modulator for a large‐scale accelerator. The voltage generator consists of a conventional capacitor discharge type pulse voltage generator and series cascaded voltage compensators. By using the voltage compensators, higher voltage fluctuation of the bank capacitor is acceptable; therefore, its capacitance and the dimensions of the capacitors can be low. This paper discusses the control strategy of the voltage compensators and thyristors for DC voltage supply for the highly fluctuating capacitor voltage, and demonstrates this by a laboratory‐scale experimental setup. 相似文献
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Masaki Yamada Akihiro Suzuki Akihiko Iwata Toshiyuki Kikunaga Hajimu Yoshiyasu Kazuo Yamamoto Nobuhiko Hatano 《Electrical Engineering in Japan》2006,154(3):56-64
This paper presents the efficient operation method of the interdependent use of condenser energy on the new concept of voltage transient sag compensator. This compensator consists of the series connection inverter units, and each inverter unit generates a different output voltage by 2n times. The method proposed here, in any case of various levels of transient voltage sags on the power line, provides the efficient use of condenser energy of all these inverter units. The method of interdependent use of condenser energy is also verified by the experiment. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 154(3): 56–64, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20290 相似文献
11.
Shuhei Kato Miao‐Miao Cheng Hideo Sumitani Ryuichi Shimada 《Electrical Engineering in Japan》2012,181(1):36-44
Flywheel energy storage systems can be used as an uninterrupted power supply system because they are environmentally friendly and have high durability. The use of a simple voltage sag compensator with a low‐speed heavy flywheel and a low‐cost squirrel‐cage induction motor/generator is proposed. First, the ability of the proposed system to maintain the load voltage at 100% when the grid is experiencing voltage sag is validated experimentally. Next, design guidelines for the flywheel stored energy are discussed. Experimental verification of a 50‐kW‐class system is carried out, and the results show good agreement with the developed design guidelines. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(1): 36–44, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21252 相似文献
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Toshiro Matsumura Toshiyuki Uchii Yasunobu Yokomizu 《Electrical Engineering in Japan》1999,127(1):31-38
This paper proposes a new type of fault current limiter (FCL), which consists of a high‐TC superconducting (HTS) element and two coils wound on the same core without any leakage magnetic flux. In this FCL, either the limiting impedance or the initial limiting current level can be controlled by adjusting the inductances and the winding direction of the coils. Therefore, this FCL could relax the material restrictions on high‐TC superconducting FCL. A current‐limiting experiment by a model FCL was carried out, and the limiting performance was observed. The initial limiting current level of the model FCL was 1.7 times higher than the critical current of the HTS element, and the fault current is suppressed to 52% immediately after the short‐circuit in the test. Considering voltage–current characteristics of a high‐TC superconductor in a computer simulation, the calculated results almost agreed with the experimental results. © 1999 Scripta Technica, Electr Eng Jpn, 127(1): 31–38, 1999 相似文献
13.
加装故障电流限制器是限制短路电流的实用有效手段。故障电流限制器电抗值选择的传统做法是采用多次试探法,即反复在电网中串联一定规格的电抗器,然后计算原网络中短路电流超标母线的短路电流。本文推导了母线短路电流、故障电流限制器安装支路短路电流与开路阻抗、连接线路阻抗及串联电抗值之间的函数关系解析式,提出了故障电流限制器的参数选择的解析法,例证了方法的可行性。所提方法有助于分析电网短路电流水平对于限流电抗的敏感度,便于选择故障电流限制器的合理装设地点。相对原试探法,该方法大大减少了计算时间,可直接应用于故障电流限制器的参数选择。 相似文献
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《IEEJ Transactions on Electrical and Electronic Engineering》2017,12(4):608-614
This paper presents a novel scheme of a multi‐output power supply for solid‐state switches based on series‐connected semiconductor devices. By using the loosely transforming method, the system can realize high‐voltage isolation and a compact size, and its application range can be easily expanded to modular designed switch stacks for higher power ratings. The circuit structure and working principles are described. Based on the system operating equations, the design methodology is proposed and applied for parameter specification of a power supply system of two series‐connected switch stacks containing 20 outputs. Detailed calculations are given, and experimental results prove the feasibility of the proposed scheme. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
15.
随着电网容量的不断扩大,短路电流的限制技术已成为故障保护的一个研究热点。重点介绍一种新颖的桥式固态限流器拓扑及工作原理,并根据此原理研制了220V/2200A桥式固态限流器,正常运行时限流器阻抗几乎为零,短路时自动投入,短路电流缩减率达到50%以上。 相似文献
16.
Shuhei Kato Taku Takaku Hideo Sumitani Ryuichi Shimada 《Electrical Engineering in Japan》2009,167(1):74-82
Flywheel energy storage systems are attracting attention as uninterruptible power supplies (UPS) from the viewpoint of environmental friendliness and high durability performance. Using a low‐speed, heavy flywheel and a low‐cost squirrel‐cage induction motor/generator, two applications are proposed: (1) an 11‐kW voltage sag compensator using a capacitor self‐excited induction generator without semiconductor converters and (2) a UPS composed of the flywheel system and an engine generator. Based on experimental results, an ideal voltage sag compensator and UPS are realized by the low‐technology flywheel system. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(1): 74– 81, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20784 相似文献
17.
Iwao Shimizu Yuji Naito Iwao Yamaguchi Katsuyuki Kaiho Satoru Yanabu 《Electrical Engineering in Japan》2006,155(4):20-29
Using high‐temperature superconductors, a superconducting fault current limiter (SFCL) was fabricated and tested. The superconductor and a vacuum interrupter serving as a commutation switch were connected in parallel with a bypass coil. When a fault occurs and excessive current flows, the superconductor is first quenched and the current is transferred to the bypass coil because of the voltage drop of the superconductor. At the same time, since a magnetic field is generated by the current flowing in the bypass coil, the commutation switch is immediately driven by an electromagnetic repulsion plate connected to the driving rod of the vacuum interrupter (VI), and the superconductor is separated from this circuit. Using the test model, we were able to separate the superconductor from the circuit by the movement of the VI within a half current cycle and to transfer all current to the bypass coil. Since the operation of the commutation switch is included in the current limiting operation of this test model, it will be a useful circuit in the development of SFCL in the future. Moreover, since it can make the energy consumption of the superconductor small during the fault state due to the realization of a high‐speed switch with simple composition, the burden on the superconductor is reduced compared with the conventional resistive type of SFCL and it is considered that the flexibility of SFCL design is increased. Cooperation with a circuit breaker was also considered; trial calculations of the parameters and energy of operation were conducted and a discussion of the installation of the SFCL in an electric power system is presented. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(4): 20–29, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20265 相似文献
18.
Toshiro Matsumura Keita Mutsuura Yasunobu Yokomizu Hirotaka Shimizu Masatoyo Shibuya Tanzo Nitta Hiroyuki Kado Michiharu Ichikawa 《IEEJ Transactions on Electrical and Electronic Engineering》2006,1(3):276-284
Fault current limiters (FCLs) are expected to reduce fault current and improve stability of power systems. A flat type fault current limiter consisting of the pancake primary winding and a high‐Tc superconducting (HTS) disk was proposed as a modified version of a conventional magnetic shield type of the FCL with the superconducting cylinder. The flat type FCL has the advantage of being manufactured smaller than the cylinder type FCL. It is pointed out, from a magnetic field analysis, that the volume of the flat type FCL is smaller than that of the cylinder type FCL with same magnitude of the limiting inductance. Further, the magnetic field analysis suggests that a high inductance ratio can be realized by radially enlarging both the primary winding and the HTS disk, stacking the FCL modules in layers and sandwiching the primary winding with superconducting disks. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
19.
We examined the possibility of the practical use of a conduction‐cooled magnetic shield type fault current limiter. A small superconducting fault current limiter was built and the current limiting characteristics were tested. Conceptual design of the conduction‐cooled fault current limiter for a distribution power system was carried out, and we calculated and discussed the temperature rise of shielding coil during a normal and a fault condition. We suggest a protection method for quench due to local disturbances during normal operation. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(1): 20–27, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10164 相似文献