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具有可控串联补偿的新型故障限流器的研究 总被引:5,自引:3,他引:2
提出一种新型的具有动态串联补偿功能的故障电流限流器,由一个固定电容器、开关控制的电容器组与旁路电感并联后再和限流电感串联而成,较以往限流器的优势在于串联补偿功能上的改进.正常时,通过投切不同的电容器组,按步长的方式来控制调整线路的补偿度;故障时,则通过和旁路电感相串联的可关断晶闸管(GTO)来控制其限流程度.在详细分析其工作原理的基础上,用MATLAB程序进行了数字仿真,结果表明,此装置性能良好,可作为电力系统中一种有效的保护设备. 相似文献
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一种新型故障电流限制器的原理研究 总被引:1,自引:0,他引:1
提出一种新型的应用柔性交流输电系统(FACTS)技术能够改善电网电能质量的故障电流限流器,其由一个固定电容器、晶闸管控制的电容器组与旁路电感并联后再和限流电感串联而成.和以往的限流器相比,其突出优点在于串联补偿功能上的改进以及用大功率自关断器件--集成门极换流晶闸管(IGCT)代替传统的门极可关断晶闸管(GTO).正常时,通过投切不同组数的电容器,按步长的方式调整控制线路的补偿度;故障时,通过和旁路电感相串联的IGCT控制其限流程度.在详细分析其工作原理的基础上,应用Matlab程序进行了数字仿真,结果表明,该装置具有良好的性能,可有效地改善电网在故障期间的母线电压暂降问题,提高了系统的电能质量. 相似文献
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具有串联补偿作用的新型故障限流器的拓扑结构和仿真 总被引:18,自引:5,他引:13
提出—种新型的具有串联补偿功能的故障电流限流器,它由补偿电容和旁路电感并联后与限流电感串联而成;和旁路电感相串联的可关断晶闸管(GTO)控制正常时的补偿度和故障时的限流程度。通过仿真分析,证明此装置效果良好,是电力系统中有用的保护设备。 相似文献
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具有中联补偿作用的新型故障限流器的拓扑结构和仿真 总被引:5,自引:0,他引:5
提出一种新型的具有串联补偿功能的故障电流限流器,它由补偿电容和 路电感并联后与限流电感串联而成;和旁路电感相串联的可关断晶闸管(GTO)控制正常时的补偿度的故障时的限流程度。通过仿真分析,证明此装置效果良好,是电力系统中有用的保护设备。 相似文献
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在采用串联电容器补偿的输电线路中,当线路发生短路故障时,故障电流流经串联电容器,在其两端会引起危险的过电压。通常设置保护回路与串联补偿电容器并联。目前采用的保护回路主要有两种类型:典型保护回路。其原理接线如图1所示。当串联电容器组 C 流过故障电流。其两端电压上升到保护间隙的击穿电压整定值(通常为 C 的额定工作电压2.5~3.5倍)时,保护间隙 P 动作,C 将通过限流电阻 R 放电。当电流互感器 CT中流过故障电流后,经继电保护装置,迅速合上并联断路器 B,则 P 被短接并灭弧。当线路短路故障被切除后,可通过 B 和分流电感 L,继续向受端输送电力。为使 C 重新投入运行,待 P 的绝缘强度恢复后,继电保护装置还能重新断开 B。这种回路的保护间隙可不采用自灭弧间隙。 相似文献
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一种改进串联谐振型限流器 总被引:1,自引:0,他引:1
串联谐振型限流器(Series-Resonant type Fault Current Limiter,SRFCL)实现故障限流的关键是电容器的旁路(或短路)操作。本文通过引入双分裂电抗器,改变了电容器的旁路方法,实现了对串联谐振型限流器拓扑的改进。在理论上,分析了改进型串联谐振型限流器工作原理,并详细研究了限流过程中双分裂电抗器的电感变化特点。研究了电网稳态时双分裂电抗器绕组自感对限流电抗器和电容器的谐振关系的影响,和故障限流过程中绕组漏感对限流器的限流能力的调节作用和对电容器过流的抑制作用。通过建模仿真,分析了双分裂电抗器的漏感和电容器振荡电流的频率和幅值关系,研究了避雷器(MOV1和MOV2)残压与线路电流和电容器电流的关系。最后,在参数优化的基础上,设计和研制了一台400V改进型串联谐振型限流器样机,测试结果表明了双分裂电抗器能够提高串联谐振型限流器的可靠性和限流能力。 相似文献
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Pulsewidth modulation (PWM) control techniques for rectifiers are widely used to improve the source current waveform and the input power factor. Recently, methods to reduce the number of detectors have been studied to simplify the system configuration and control of such rectifiers. It is known that a voltage detector on the ac side can be omitted, though a voltage detector on the dc side is needed for adjustment of the dc output of a PWM rectifier. In this paper, a method for controlling a single-phase rectifier without any voltage sensor is proposed. The ac-side voltage can be estimated from the input-reactor voltage when the ac side of the bridge is short-circuited. The reactor voltage is easily obtained by multiplying the inductance of the reactor by the derivative of the source current measured. The dc side voltage can be estimated by calculating the difference between the source voltage at the beginning of every switching period and the reactor voltage sampled and held in the previous bridge conduction mode. This paper describes the control scheme, its implementation, and the performance characteristics of the rectifier. The usefulness of the rectifier is confirmed by experiment. This method is applicable to various types of PWM rectifiers. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(4): 90–96, 1997 相似文献
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A new PWM technique for the current-fed PWM converter is proposed. As the control variables, the instantaneous active and reactive powers are used instead of the line current. They are proportional to the instantaneous active and reactive current vector. The switching state of the PWM converter is given by the selection method of the appropriate current vector among the seven kinds of the current vectors with the zero current vector. The active current is controlled by the zero current vector and the reactive current depends on the kind of selected current vector. These variables basically are controlled by PWM switching from two kinds of hysteresis comparator. In addition to this, the compensation of the filter circuit can be obtained automatically by the PWM control based on the active and reactive current detected from the source current. In this paper, the principle of the PWM technique for the current-source PWM converter is proposed. Then, some simulation results are shown. After that, the feasibility of the system is verified by experimental results. 相似文献
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传统电抗器电抗值的测量方法为外加三相对称电压源的方法,而电抗器的设计是按三相对称电流源设计的,在实际运行中电抗器两端相当于外接-个对称三相电流源,因此,用传统的测量方法必定引起测量误差.为了改变传统测量电抗器电抗值,本文介绍了一种基于PWM控制的方法,能够在额定电流下进行阻抗测量,且电源为三相对称电流源.测量系统由DSP控制、MOSFET构成PWM逆变电路的测量方法,能够在三相对称电流源下测量,而不是三相对称电压源,减小了测得的电抗值与实值的误差.选用此测量方法与传统方法相比,具有设备体积小,测量精度高的优点. 相似文献
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Yasuhiko Neba 《Electrical Engineering in Japan》1998,123(3):36-45
A current source type converter can easily generate a sinusoidal current on the ac side by employing a PWM strategy. In the converter system for a single-phase supply, however, the dc current pulsates because the dc output voltage of the converter contains an ac component with twice the ac supply frequency. The dc current pulsations cause the ac current waveform to be distorted. Although the use of a dc reactor with large inductance reduces the dc current pulsations, the size and the weight of converter equipment including a dc reactor is large. Two-phase rectification using two full-bridge converters and a converter system with an ac chopper circuit has been proposed for elimination of the dc pulsations. In these converters, the number of switching devices comprising the circuit will unavoidably increase. To solve this problem, we propose a novel single-phase current source type converter coupled with an ac chopper circuit and the PWM method. In this circuit, two switching devices in the main bridge are used to form an ac chopper bridge with two added devices and a capacitor. This paper gives the experimental and theoretical waveforms and the steady-state characteristics. The results prove that a smooth dc current and a sinusoidal ac current are obtained, and that a great reduction of the dc inductance can be achieved by using the proposed converter. © 1998 Scripta Technica. Electr Eng Jpn, 123(3): 36–45, 1998 相似文献
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方波无刷电动机的倍频PWM控制方法 总被引:2,自引:0,他引:2
针对传统PWM方波控制方法受开关频率限制,很难应用于某些小电感方波无刷电机驱动场合,提出了一种倍频PWM控制方法.这种方法力图在功率开关的开关频率不变的情况下,使永磁无刷电动机绕组的充放电频率提高为开关频率的二倍,减小绕组电流波动,改善绕组电流波形.分析了倍频PWM控制方法的工作原理,采用XC886为主控芯片实现了对一个相电感为125μH永磁无刷电机的倍频PWM控制.实验结果表明绕组的充放电频率升高一倍后,稳态电流的纹波小于10%,绕组的电流波形很接近方波,验证了相关分析的正确性. 相似文献