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Author: h.gras
Type: Model
Downloaded: 428 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: 328 times
Date: 2016-03-22

PLLs

Description:
Some PLLs:
- zero crossing
- dq0
- alpha beta
- EPLL
- UTSP

Tag(s): PLL, frequency, tracking, PMU

Author: n.sene
Type: Publication
Date: 2015-04-01

On the Mitigation Effect of Surge Arresters on the Lightning Performance of Overhead Distribution Lines

Description:
For the accurate statistical assessment of the lightning performance of distribution lines one needs to
take into account the presence of protection devices such as surge arresters and shielding ... see morewire/neutral
groundings. Indeed, the presence of those devices can significantly modify the indirect lightning
response of the overhead line and, therefore, the relevant lightning performance.
In particular, this paper aims at investigating the impact of the presence of surge arresters on the
indirect lightning performance of overhead distribution lines having realistic configuration.
Specifically, reference is made to typical Italian distribution lines. The investigation is performed with
the help of a statistical procedure developed by the authors – based on the Monte Carlo method and of
the use of an accurate modelling/calculation tool for the induced surges – that has been recently
compared with one proposed in the IEEE 1410 Std for the same purpose, and shown to be more
complete and suitable for the problem of interest. The paper also aims at investigating the influence of
the presence of surge arresters on the indirect lightning surges transferred through power transformers.
Such an additional investigation is performed by means of a suitable high-frequency power
transformer mode integrated with the lightning-induced computation tool.

Authors: A. Borghetti, F. Napolitano, C.A. Nucci and M. Paolone - University of Bologna, Italy

CIGRE – Colloquium Cavtat - Application of Line Surge Arresters in Power Distribution and Transmission Systems

Tag(s): Lightning statistics, induced overvoltages, lightning performance of distribution lines, surge arresters, shielding wires groundings, Monte Carlo method.