Exchange Platform

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

Author: n.sene
Type: Publication
Date: 2015-04-02

Short-Term Scheduling of Active Distribution Systems

Description:
The latest distribution management systems tend to incorporate optimization functions for the short-term scheduling of the various energy and control resources available in the network (e.g., embedded... see more generators, reactive power compensators and transformers equipped with on-load tap changers). The short-term scheduling procedure adopted in the paper is composed by two stages: a day-ahead scheduler for the optimization of distributed resources production during the following day, an intra-day scheduler that every 15 minutes adjusts the scheduling in order to take into account the operation requirements and constraints of the distribution network. The intra-day scheduler solves a non-linear multi-objective optimization problem by iteratively applying a mixed-integer linear programming (MILP) algorithm. The linearization of the optimization function and the constraints is achieved by the use of sensitivity coefficients obtained from the results of a three phase power flow calculation. The paper shows the application of the proposed approach to a medium-voltage 120 buses network with 10 dispatchable generators and 2 transformers equipped with on-load tap changers.

Authors: A. Borghetti, M. Bosetti, S. Grillo, M. Paolone, F. Silvestro

IEEE Bucharest Power Tech Conference, June 28th - July 2nd, Bucharest, Romania

Tag(s): Distributed generation, operation of distribution networks, MILP.

Author: n.sene
Type: Publication
Date: 2015-04-02

Indirect Lightning Performance of a Real Distribution Network with focus on Transformer Protection

Description:
The paper applies the Monte Carlo procedure proposed by the Authors to evaluate the indirect lightning performance of a real medium-voltage distribution network, which includes feeders and laterals, p... see moreoles, secondary substations and surge protection devices. Such a procedure allows inferring the amplitude of lightning-induced voltages at any point and any phase of the network. The analysis presented in this paper aims at assessing the expected mean time between failures of each MV/LV transformer caused by indirect lightning strikes.
A heuristic technique has been specifically developed to reduce the computational effort despite the non-linear response of the network enhanced by the presence of surge arresters.

Authors: Alberto Borghetti, Fabio Napolitano, Carlo Alberto Nucci, Fabio Tossani, Gilnei J. G. Dos Santos, Donorvan R. Fagundes, Gustavo P. Lopes, Manuel L. B. Martinez

2014 International Conference on Lightning Protection (ICLP), Shanghai, China

Tag(s): induced voltages; distribution networks; Monte Car lo method; lightning protection; MTBF.

Author: n.sene
Type: Publication
Date: 2015-04-02

Selection of MV/LV Transformers to be Protected by Surge Arresters against Indirect Lightning Overvoltages

Description:
The papers addresses the problem of locating surge protective devices in a medium voltage distribution network by means of an accurate computer model for the calculation of lightning induced overvolta... see moreges and a Monte Carlo statistical procedure. The indirect lightning performance of small network cells of different configuration are evaluated and used as a benchmark for the validation of the surge arrester locations provided by a genetic algorithm procedure. The obtained results appear useful for the lightning protection design of networks
with complex topology.

Authors: Alberto Borghetti, Fabio Napolitano, Carlo Alberto Nucci, Fabio Tossani, Gilnei J. G. Dos Santos, Donorvan R. Fagundes, Gustavo P. Lopes, Manuel L. B. Martinez

2014 International Conference on Lightning Protection (ICLP), Shanghai, China

Tag(s): distribution network; surge arresters; lightning protection.

Author: n.sene
Type: Publication
Date: 2015-04-02

Indirect-Lightning Performance of Overhead Distribution Networks With Complex Topology

Description:
The paper deals with the evaluation of the indirect-lightning performance of overhead distribution networks. The novelty of this contribution is that it takes into account the inherent complexity of d... see moreistribution networks. These networks are indeed characterized by a plurality of lines (main feeder and laterals) and also by the presence of typical power components (e.g., transformers and surge arresters); they consequently differ considerably from the straight line configuration generally adopted in this type of studies.
To accomplish such an evaluation we have extended the general procedure already presented in a previous paper based on the use of the LIOV code along with the Monte Carlo method. The extended procedure combines the advantage of the LIOV-EMTP computer code—that allows the calculation of lightning-induced voltages in complex distribution networks—with a heuristic technique specifically developed and integrated in the Monte Carlo routine in order to reduce the computational effort. The application of the proposed procedure to a set of distribution overhead networks characterized by different topologies, but all of the same length, shows that, in general, the usual single straight-line approach may result into a misestimation of the indirect-lightning performance. The paper also analyzes and discusses the influence of both the line terminations, and the position of the line poles.

Authors: Alberto Borghetti, Senior Member, IEEE, Carlo Alberto Nucci, Fellow, IEEE, and Mario Paolone, Member, IEEE

IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 24, NO. 4, OCTOBER 2009

Tag(s): LIOV-EMTP, lightning-induced overvoltages, lightning performance, power quality, distribution systems, overhead power lines.