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针对光伏电源和风电低压并网系统,备自投的动作进行了分析,提出了备自投动作的改进方法,保证了用户的电能质量。 相似文献
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就380V低压备自投动作情况进行了分析,并如何避免备自投动作合于故障点进行了阐述,在减少设备风险,提高供电可靠性,提出了措施和可行方案,如改变备自投运行方式,减少备自投动作判据,改变低压所用变保护装置配置等。 相似文献
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为了提高供电可靠性,在一些重要的负荷场合高压配电房往往设计成两进线带母联的方案,两进线和母联之间要实现母联备自投。母联备自投逻辑一般都需要判断母线电压,但是有些时候为了节省预算,往往不设专门的母线PT柜,这就使得备自投装置无法取得母线电压,备自投逻辑不能完整实现,本文的目的在于研究当没有母线PT柜情况下的母线备自投解决方案。 相似文献
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通过对动作情况的分析,把备自投的加速功能分为两类,第一类是在对应的工作开关已跳开的情况下,瞬时补跳,再合备用开关;第二类是在备投动作合闸于故障或手合于故障时,加速跳开关。比较第二类备投加速与母联保护在无母联保护的母线故障时的动作效果,并对“第二类加速”提出改进,建议备投装置中能设置“备投合于故障加速跳母联”功能。 相似文献
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备用电源自投装置动作可靠性高,因而在电力系统中得以广泛应用。本文介绍了110kV某用户变电站采用内桥式接线备用电源自投装置不正确动作的案例,对其不正确动作原因作了详细分析,并依据现场实际情况,对备自投装置在应用过程中存在的细节问题进行探讨,最后提出了改进方法。 相似文献
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根据备自投保护的动作原理对现场工作中发现的备自投保护存在着一些问题和不安全因素进行分析,并通过引入压变二次空开辅助接点和增加“充电完成”后台信号对备自投保护进行改造,提高备自投动作可靠性,避免大面积停电事故,从变电站安全运行的角度论述改造方案的可行性。 相似文献
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110kV线路备自投装置正确动作时可以提高供电可靠性,而当备自投装置动作不正确时,会严重影响电网的安全运行,有可能会造成变电站全站失压,损失负荷,严重时还将导致一次设备损坏。本文介绍了LFP-965B系列备用电源自投装置的一次不正确动作过程,对相关的问题进行了分析,并且对备自投提出改进措施、解决问题的方法。实施使用后,取得很好的效果。 相似文献
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分布式小水电接入配电系统后,改变配电网络的拓扑结构和潮流方向,对备自投装置带来较大的影响。通过对这种装置的工作状态的定性分析、仿真计算,得出了对于备自投,由于小水电对母线的电压支撑作用,导致不能动作而失效,并对这种装置提出适合有分布式小水电存在的线路的改进措施,提高了电网的安全稳定性和供电可靠性。 相似文献
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备自投装置是提高供电可靠性的安全自动装置之一,在发电厂、变电站中已得到广泛应用,但在某些特定场合下备自投的常用切换方式无法满足特殊运行方式的要求,需改由其它切换方式来实现。本文详细介绍了备自投远方自投在实际工程中的应用。 相似文献
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A microfluidic device integrated with 3D thin film microelectrode arrays wrapped around serpentine-shaped microchannel walls has been designed, fabricated and tested for cell electrofusion. Each microelectrode array has 1015 discrete microelectrodes patterned on each side wall, and the adjacent microelectrodes are separated by coplanar dielectric channel wall. The device was tested to electrofuse K562 cells under a relatively low voltage. Under an AC electric field applied between the pair of the microelectrode arrays, cells are paired at the edge of each discrete microelectrode due to the induced positive dielectrophoresis. Subsequently, electric pulse signals are sequentially applied between the microelectrode arrays to induce electroporation and electrofusion. Compared to the design with thin film microelectrode arrays deposited at the bottom of the side walls, the 3D thin film microelectrode array could induce electroporation and electrofusion under a lower voltage. The staggered electrode arrays on opposing side walls induce inhomogeneous electric field distribution, which could avoid multi-cell fusion. The alignment and pairing efficiencies of K562 cells in this device were 99% and 70.7%, respectively. The electric pulse of low voltage (～9 V) could induce electrofusion of these cells, and the fusion efficiency was about 43.1% of total cells loaded into the device, which is much higher than that of the convectional and most existing microfluidics-based electrofusion devices. 相似文献
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双PWM整流侧独立于电机侧的传统控制方式会导致的直流母线电压不稳定,为改善这一缺点,该文给出四种双PWM一体化控制策略:直流母线加装电流传感器、基于功率平衡、负载电流前馈、对直流充电电容与电感压降前馈补偿的控制策略,建立MATLAB仿真模型,并验证了双PWM一体化控制策略具有可行性。 相似文献
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This paper presents a multi objective differential evolution (MODE) based voltage security enhancement through combined preventive-corrective control strategy. Load shedding, generation rescheduling and optimal utilization of FACTS devices are considered for security enhancement. Maximum l-index of load buses is taken as the indicator of voltage stability. Minimization of cost of FACTS devices, minimization of amount of load shedding along with improvement in voltage stability are the objectives of this multi objective optimization problem. The optimal location of FACTS devices are selected using modal analysis technique. The buses for load shedding are selected based on the minimum eigen value of load flow Jacobian. The proposed MODE algorithm employs DE/randSF/1/bin strategy scheme with self tuned parameter which employs binomial crossover and difference vector based mutation. A fuzzy based decision making algorithm is employed to get the best compromise solution from the non dominated solutions. The proposed MODE is also tested with statistical performance metrices. The proposed methodology is implemented on IEEE 30 bus and IEEE 57 bus test systems. The proposed MODE method provides better solutions in the pareto optimal front than the other optimization techniques such as MOGA and NSGA II under combined preventive–corrective control approach. In IEEE 30 bus system, the amount of load shedding is reduced by 40% and voltage stability is improved by 15% and in IEEE 57 bus system, the amount of load shedding is reduced by 15.4% and voltage stability is improved by 13% by the proposed approach. Hence the simulation results show that the proposed approach provides considerable reduction in the amount of load shedding and enhancement of voltage stability by including generation rescheduling and utilization of FACTS devices. 相似文献
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A simple and effective universal serial bus (USB) flash disk type microfluidic chip electrophoresis (MCE) was developed by using poly(dimethylsiloxane) based soft lithography and dry film based printed circuit board etching techniques in this paper. The MCE had a microchannel diameter of 375 μm and an effective length of 25 mm. Equipped with a conventional online electrochemical detector, the device enabled effectively separation of bovine serum albumin, lysozyme, and cytochrome c in 80 s under the ultra low voltage from a computer USB interface. Compared with traditional capillary electrophoresis, the USB flash disk type MCE is not only portable and inexpensive but also fast with high separation efficiency. 相似文献
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本文在传统变频装置的基础之上,采用三相电压型PWM整流器代替原有的电力二极管不控整流,从根本上解决了变频器整流单元对电网的污染问题。实现了电能回馈电网,以实现理想的四象限变频传动。利用TI公司的TMS320LF2407ADSP设计了双侧PWM电压源变换器硬件实现原理图,并给出了系统的软件实现。 相似文献
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We report on reversible electroporation of cells in a flow-through microfluidic device, whereby the required electric field is delivered through a set of integrated microcapillaries between a centre stream of cells and side streams of liquid electrolytes. The electrolytes are applied with a sine wave voltage and cells flow by the microcapillary openings encounter a burst of ac field with a duration and strength determined by their average speed and spatial proximity to the microcapillary openings, respectively. Effectiveness of the approach is presented through numerical simulations and empirical results on electroporation efficiency and cell viability against various flow rates (exposure time to the field) as well as frequencies and root-mean-square (rms) intensities of the field. High frequencies (80–400 kHz) and high intensities (e.g., 1.6 kV/cm, rms) are identified with increased electroporation efficiency 61% and viability 86% on average. These results suggest that the device demonstrated here with a simple design and robust operation offers a viable platform for flow-through electroporation. 相似文献
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给出了基于AMBA2.0总线的DMA控制器的RTL级设计,并搭建了SoC仿真平台进行功能仿真,最后进行了FPGA原型验证.在100MHz的工作频率下,仿真和验证结果表明,本设计可以满足功能和性能的要求. 相似文献