Exchange Platform

Author: h.gras
Type: Model
Downloaded: 427 times
Date: 2018-06-08

Vacuum Circuit breaker (VCB)

Description:
Three main characteristics of VCBs have been taken into account in the implemented model:
1. the chopping current value;
2. the cold withstand voltage characteristic (or cold gap breakdown v... see moreoltage);
3. the high frequency current quenching capability.

Ref: Transient Recovery Voltages in Vacuum Circuit Breakers Generated by the Interruption of Inrush Currents of Large Motors
A. Borghetti, F. Napolitano, C.A. Nucci, M. Paolone, M. Sultan, N. Tripaldi

Tag(s): Vacuum, circuit breaker, VCB,

Author: thpapad
Type: Document
Downloaded: 124 times
Date: 2017-11-03

MIMO-OFDM Narrowband-PLC in Distribution Systems: Impact of Power Transformers on Achievable Data Rates

Description:
Power-line communication (PLC) is gaining a renewed interest, due to the smart grid (SG) emerging communication requirements. Among other communication technologies, PLC is a very efficient and feasib... see morele solution, especially for the extended SG distribution networks. However, it is very challenging to consider both the medium- and low-voltage parts of the distribution network as a whole communication medium, due to the attenuating effects of distribution transformers, limiting PLC applicability. In this paper, data transmission through distribution transformers is investigated by means of multiple-input multiple-output (MIMO) narrowband power-line communication (NB-PLC) system, utilizing orthogonal frequency-division multiplexing (OFDM) technology. Multi-conductor distribution line and measurement-based transformer models are developed to characterize the MV-LV PLC channel. In addition, OFDM signal processing techniques are applied to enhance the achievable data rates. The transmit power budget and bit allocation across the OFDM sub-channels of the spatial beams are optimized to maximize the data rate through the distribution transformer. The achievable data rates are calculated and systematically analysed for different scenarios to investigate the effects of the distribution lines, connected loads, noise models, etc. Results reveal the superiority of the proposed MIMO design against the traditional SISO systems. In addition, the possibility for an extensive and reliable application of MV-LV PLC communications through distribution transformers is shown.

Tag(s): Distribution lines, distribution transformers, MIMO-OFDM, power-line communication, smart grids

Author: thpapad
Type: Document
Downloaded: 343 times
Date: 2017-11-03

INDUCED VOLTAGES AND CURRENTS: OVERVIEW AND EVALUATION OF SIMULATION MODELS AND METHODOLOGIES

Description:
In this paper induced voltages and currents caused by underground cables are calculated in cable sheaths and nearby metallic pipelines. The performance of several simulation methods and models are inv... see moreestigated in steady-state, considering also different implementations in ATP-EMTP, EMTP-RV and PSCAD/EMTDC. The analysis is extended in the simulation of transient overvoltages in cable systems, evaluating the accuracy of two widely used simulation models. The influence of different parameters is investigated, among them specifically the earth properties. Results reveal that implementing accurate earth representations, earth conduction effects have a significant impact on induced voltages at the power frequency, while for high frequency phenomena the influence is minor.

Tag(s): induced voltages

Author: h.gras
Type: Model
Downloaded: 166 times
Date: 2017-09-26

LVRT OVRT function

Description:
This device is an OVRT LVRT protection device.
The user enters the curves points.
It is assumed that the curve is horizontal between two points.

Tag(s): LVRT, OVRT, ride, through, FRT, undervoltage, overvoltage

Author: n.sene
Type: Publication
Date: 2015-10-22

Fault Current Limiters in Industrial Power Systems

Description:
The concept of saturable core fault current limiter (FCL) is relatively known nowadays. It usually consists of two reversely magnetized cores per phase to effectively limit the fault current passively... see more and immediately upon its inception. In this paper prospects of application of fault current limiters in industrial power systems will be considered. Industrial power systems (distribution networks) are widespread and include a number of various electrical appliances. The power systems development (addition of new power plants, interconnections, etc.) may lead to more intense short circuit currents at the fault location. Furthermore, industrial systems may possess on-site generation which can increase fault current levels as well. All these factors might require appropriate upgrades of industrial system electrical equipment (especially switchgear) or special operating procedures (for instance avoiding parallel operation). Another alternative is the installation of fault current limiters. In this light, a series of simulations were carried out in order to observe the impact of fault current limiters on short circuit currents in an industrial power system using the EMTP-RV software program.

Keywords: saturable core fault current limiter (FCL), industrial power system, induction machine, EMTP; fault current analysis, medium voltage

Tag(s): saturable core fault current limiter (FCL), industrial power system, induction machine, EMTP; fault current analysis, medium voltage