共查询到10条相似文献，搜索用时 421 毫秒
1.
This paper presents a new type of fault current limiter(FCL) based on fast-closing switch,which is composed of a capacitor bank and a reactor in series.The main control component is a fast-closing switch connected in parallel with the capactitors,which is drien by the electromagnetic repulsion force.It can response the order within 1 ms.When fault occurs,the switch closes and the capacitors are bypassed.and the fault current is limited by the reactor,Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast-closing switch,it is feasible to develop the FCL with low cost and high reliability. 相似文献
2.
Short circuit is a serious fault in power network. Some novel circuit topologies of current limiter using power electronic
technology have been developed, which can limit the fault current to any desired level without much penalty. The operating
principle and control strategies of such current limiters are discussed in detail. Simulation and experimental results are
given to verify the performance of the current limiter, which can meet the requirements set for locations of bus tie, feeder,
as well as the main transformer in the distribution network.
Project(59777022) supported by National Natural Science Foundation of China(NSFC) 相似文献
3.
SHORT CIRCUIT CURRENT LIMITER IN AC NETWORK 总被引：13，自引：0，他引：13
ＩＮＴＲＯＤＵＣＴＩＯＮＳｈｏｒｔｃｉｒｃｕｉｔｉｎｐｏｗｅｒｓｙｓｔｅｍｓｉｓａｓｅｒｉｏｕｓｆａｕｌｔ,ｗｈｉｃｈｍａｙｄａｍａｇｅｔｈｅｅｑｕｉｐｍｅｎｔｉｎｔｈｅｓｙｓｔｅｍ .Ｉｔｒｅｑｕｉｒｅｓｔｈｅｐｒｏｔｅｃｔｉｏｎｓｙｓｔｅｍｔｏｓｗｉｔｃｈｏｆｆｔｈｅｖｅｒｙｈｉｇｈｌｅｖｅｌｏｆｆａｕｌｔｃｕｒｒｅｎｔ.Ｔｈｅｔｒａｄｉｔｉｏｎａｌｍｅｔｈｏｄｔｏｌｉｍｉｔｔｈｅｓｈｏｒｔｃｉｒｃｕｉｔｃｕｒｒｅｎｔｌｅｖｅｌｉｓｔｏｓｅｒｉａｌｌｙｃｏｎｎｅｃｔａｌｉｍｉｔｉｎｇｒｅ ａｃｔ… 相似文献
4.
在传统故障诊断基础上，将多Agent技术（MAS）应用于复杂系统故障诊断领域，是求解复杂过程故障诊断问题的一种新尝试．研究了基于MAS的分布式智能故障诊断模型，基于一种分布式Agent诊断系统结构原型系统，重点研究了诊断问题的任务辨识、分解问题，构建了基于Agent的任务分配的综合遗传算法和模拟退火算法的混合算法．应用表明，该算法具有很好的可扩展性、适应性和稳定性． 相似文献
5.
A discipline apart: the challenges of ‘Fostering a Community of Learners’ in a mathematics classroom
This is the fifth in a series that examines the challenges that teachers in different domains face as they attempt to implement the pedagogical reform ‘Fostering a Community of Learners’ (FCL). Here we focus on the relationship between FCL and the teaching of mathematics. We argue that it is possible to teach mathematics through the FCL pedagogy, but that doing so requires some rethinking of both mathematics instruction and FCL. In particular, we describe three shifts that aided a teacher's implementation of FCL pedagogy with mathematics: the teacher developed a new perspective on mathematics that emphasized the importance of having students learn both mathematical concepts and processes; the teacher developed a new understanding of the role of the teacher in mathematics‐education reform; and the teacher modified his understanding of FCL, coming to believe that a discourse community could be the basis for FCL pedagogy in a mathematics classroom. 相似文献
6.
A diagnostic signal current trace detecting based single phase-to-ground fault line identifica- tion and section location method for non-effectively grounded distribution systems is presented in thisi oaper. A special diagnostic signal current is injected into the fault distribution system, and then it is de- tected at the outlet terminals to identify the fault line and at the sectionalizing or branching point along the fault line to locate the fault section. The method has been put into application in actual distribution network and field experience shows that it can identify the fault line and locate the fault section correctly and effectively. 相似文献
7.
Multiple learning communities: students,teachers, instructional designers,and researchers 总被引：2，自引：2，他引：0
ALAN H. SCHOENFELD 《课程研究杂志》2013,45(2):237-255
Fostering a Community of Learners (FCL) exemplifies a class of pedagogical approaches aimed at having students become reasoners and sense‐makers in various content domains. While the pedagogical practices among these approaches vary to some degree, they tend to overlap in philosophy and general pedagogical style. Hence issues confronted by those attempting to implement FCL will be confronted by those hoping to implement similar activities. The three‐level commentary in this paper begins with specific reactions to the preceding papers, which focused on attempts to implement FCL in different content areas. It continues with a discussion of what counts in FCL: for example, is it a set of participant structures such as jigsawing, or a set of underlying principles? It concludes with a discussion of systemic issues that will be faced by any pedagogical approach focusing on having students engage in reasoning and sense‐making in the classroom. 相似文献
8.
Yin-jun Wang Cheng Zhuo Jun-yong Deng Jin-fang Zhou Kang-sheng Chen 《浙江大学学报(A卷英文版)》2008,9(6):849-857
Power integrity （PI） has become a limiting factor for the chip＇s overall performance, and how to place in-package decoupling capacitors to improve a chip＇s PI performance has become a hot issue. In this paper, we propose an improved transmission matrix method （TMM） for fast decoupling capacitance allocation. An irregular grid partition mechanism is proposed, which helps speed up the impedance computation and complies better with the irregular power/ground （P/G） plane or planes with many vias and decoupling capacitors. Furthermore, we also ameliorate the computation procedure of the impedance matrix whenever decoupling capacitors are inserted or removed at specific ports. With the fast computation of impedance change, in-package decoupling capacitor allocation is done with an efficient change based method in the frequency domain. Experimental results show that our approach can gain about 5× speedup compared with a general TMM, and is efficient in restraining the noise on the P/G plane. 相似文献
9.
HU Jia-bing HE Yi-kang 《浙江大学学报(A卷英文版)》2006,7(10):1757-1764
INTRODUCTION Due to concerns about emissions from fossil fuels and the depletion of fossil fuel resources, re- newable energy systems are becoming a topic of great interest and investment in the world. In particular, wind energy has been the subject of much recent research and development. In order to overcome the problems associated with fixed-speed wind-turbine system and to maximize the wind energy capture, many new wind farms will employ wind turbines based on Doubly-Fed Induction Ge… 相似文献
10.
A novel direct-drive type wind power generation system based on hybrid excitation synchronous machine (HESM) is introduced
in this paper. The generator is connected to an uncontrollable rectifier, and a fully controlled voltage-source inverter is
used to connect the system to utility grid. An intermediate DC bus exists between the rectifier and inverter. A new control
strategy is proposed which achieves the maximum power point tracking (MPPT) with the control of excitation current of HESM
and stabilizes the DC link voltage with the control of inverter output current simultaneously. Specially-designed buck circuit
is used to control the excitation current of HESM, and grid voltage-oriented vector control strategy is employed to realize
the decoupling of the inverter output power. Simulation results and experiment in 3 kW lab prototype show an excellent static
and dynamic performance of the proposed system. 相似文献