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The switching surge occurs due to the transient phenomenon in the opening and closing operation of the high voltage circuit breaker. It puts a strain on the circuit breaker components. The controlled switching device for high voltage circuit breaker reduces the contact wear and the stress applied to the component by minimizing the switching surge by controlling the contact moment during the switching...
Nowadays the phase controlled switching is a preferred method for capacitive switching. Thus the distribution of prestrike gaps is an important issue for the control strategy. The objective of this paper is to understand the distribution of prestrike gaps for the contact materials manufactured by arc-melted and infiltration preparing technology in the capacitive service condition of 40.5kV vacuum...
DC circuit breakers (DCCBs) are an essential component for protecting multi-terminal HVDC transmission systems. DCCBs are required to have rapid fault clearing and high current interruption, as well as low power loss under normal operation. A hybrid DCCB constituted of a semiconductor breaker and a mechanical switch was investigated to achieve rapid fault clearing, within 3 ms, and interruption of...
Currently, and increasingly, education uses technology to support teaching and learning processes, the present work shows a system to determine the best instructional techniques, taking into account students' learning styles, using a modification of the Felder and Soloman test. This modification, called FuzzyILS, was performed by Silva, Vicari and Ponce in 2016, and proposes the fuzzy of Felder and...
This paper presents a study of sensitivity of the equivalent circuit of ZnO surge arresters based on the model proposed by the IEEE. The main contribution of the proposed paper consists in some modifications in the fitting procedure of the equivalent LRC circuit of the surge arrester in order to improve the accuracy during electromagnetic transient simulations in power systems. The proposed equivalent...
This publication aims on comparing the performance of various types of surge arrestors (metal oxide varistors MOV, surge protective devices SPD and gas discharge tubes GDT) under single and multi-pulse current impulses of waveshape 8/20 μs/μs and 10/350 μs/μs. Lightnings consist in their majority of multiple strokes with a few milli seconds time interval. However, the current standards define tests...
This paper presents the main features of a system for measuring lightning currents and induced voltages on an instrumented tower and an experimental line, respectively. The tower height is 70 m, and the line, which has a non-conventional configuration, is 800 m long. The line has two conductors separated by 6 m, one with surge arresters and the other without protection. The voltages are measured simultaneously...
We applied the inverter circuitry to investigate the feasibility of reducing current surges occurred as organic light-emitting diode (OLED) pixels undergo alternating-current driving scheme in active-matrix organic light-emitting display (AMOLED) and discovered that the current surge can decrease 3.64% by peak-to-peak comparison via SPICE simulation.
In this paper is presented a Matlab graphical user interface useful to compute the thermal and dielectric stresses which means the parameters computation of the short circuit currents or transient recovery voltages which appear during the fault regimes in the high voltage networks. The analysis of the electrical stresses is carried out for the high voltage substations from ST Craiova. The Matlab GUI...
This paper assess the efficiency of installing surge arresters only in one or two phases in terms of the lightning performance of TL. Taking as reference a typical 138-kV Brazilian transmission line, simulations are developed in ATP, considering a rigorous representation of the frequency-dependent behavior of tower-footing grounding. Preliminary results shown that considering moderate values of soil...
DC microgrids can offer many advantages for an installation in commercial applications like data centers or in private homes. In this paper, future expansion of such grids towards a bipolar architecture (e.g. ±380 VDC) is evaluated. The focus lies on various fault situations, their effects on the grid and possible solutions to maintain grid safety. For this purpose, a laboratory scale bipolar test...
Considering the dielectric and mechanical characters of controlled switching (CS) in a compensation line, an EMTP-ATP model of a substation is established to analyze inrush current and reignition in the switching operation, and the optimum switching strategy is proposed. The results confirm the effect of CS on reducing series reactor in the line. The influence of reactance and chopping current on...
DC neutral breakers are used to reconfigure HVDC transmission systems. One example is the Metallic Return Transfer Breaker (MRTB) that commutates the current from the ground to an overhead line or cable reducing time duration with current flowing in the ground path. An MRTB consists of a passive LC-circuit in parallel with an AC breaker that triggers a resonance by its arc voltage characteristics,...
Vacuum circuit breaker (VCB) is a mature technology which is commonly used in medium voltage power systems worldwide. However, it is still facing challenges to switch capacitive current, especially for back-to-back capacitor bank switching. The main reason is that the inrush current can cause serious damages to the contact surfaces and further deteriorate the high voltage withstand ability of the...
Electrical energy is very important in human life. Rapid population growth resulting in increased electricity needs in Indonesia. Therefore PLN as a provider of electrical energy as possible to meet those needs. One step that is done is to plan to build a 500 kV transmission line in Sumatera. With the planned construction of the transmission line, it is also necessary planning for the distribution...
Based on the existing waveform feature recognition method, a method of recognizing transformer magnetizing inrush current by using waveform sinusoidal correlation degree is proposed. According to the difference between the transformer magnetizing inrush current and the internal fault current waveform, that is, the waveform has nature of sine function during normal operation of transformer and the...
There is the high surge current emerging when the asynchronous traction motor is replaced by PMSM with power down-rejoining on. The high back EMF voltage exists when traction PMSM is passing the switching phase insulator. The reason is due to the constant value existence of the permanent magnet. Aiming at above mentioned problems, this paper analyses the reasons of causing transient surge current...
For a three-degree-of-freedom wave energy converter (heave, pitch, and surge), the equations of motion could be coupled depending on the buoy shape. This paper presents a multiresonant feedback control, in a general framework, for this type of a wave energy converter that is modeled by linear time invariant dynamic systems. The proposed control strategy finds the optimal control in the sense that...
Many computing environments consist of a multitude of servers that process requests that arrive from a population of customers. Incoming requests that find all servers busy have to wait until a server becomes idle. This type of queuing system is known as a G/G/c system and has been extensively studied in the queuing literature under steady state conditions. In this paper we study multi-server systems...
Large inrush currents can occur when power transformers are connected to the grid. In the past, a wide range of countermeasures has been developed whereof the application of power electronic converters recently received more attention. With hybrid transformers combining a conventional transformer with a power electronic converter, the elimination of inrush currents can be realized without considerable...
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