Exchange Platform

Author: AdminEMTP-RV
Type: Model
Downloaded: 375 times
Date: 2012-06-18

Ferro_hyst_Zno

Description:
Simple ferroresonance case. In this case the switching of a part of the network comprised of a cable connected to a no-load transformer is carried out. A pole of the breaker fails to open and an impor... see moretant and stable ferroresonance phenomena appears.
The ferroresonance problem, whether in a general circuit or in a power-system circuit, is usually tackled in one of two ways : circuit configuration (i.e series and/or parallel) or nonlinearities (i.e saturation and hysteresis of transformers). A fundamental factor to the occurence of ferroresonance is the nonlinear magnetizing characteristic of the transformer and the capacitive coupling.
In this case a 250 kVA, 20/0.4 kV transformer is used. This transformer is represented by the hysteresis transformer model. The hysteresis element has been used as the magnetization branch of the one-phase transformer model. A 200 m cable is used for the study. This cable is modelled by a PI-section. The short circuit power of the source is about 150 MVA.
In order to reduce overvoltages caused by ferroresonance, surge arresters are installed. Two questions have emerged : will the arresters mitigate ferroresonance, and will they fail during ferroresonance ? Simulations in different transient regimes can be carried out in order to determine the maximal current, overvoltages (voltage at the end of the cable for instance), energy absorbed by the arresters

Tag(s): Protection

Author: AdminEMTP-RV
Type:
Downloaded: 454 times
Date: 2012-06-18

Cross_Bonded_Cable

Description:
Insulation coordination - 225 kV cross bonded cable - protection of the sheath.
In the configuration a 225 kV cross-bonded cable is connected at both ends to an otherhead line. The sheath is prot... see moreected by star-connected arresters.
The modelling used is adapted for the study of Fast-Front-Overvoltages (see IEC 60071)
A current source, with a CIGRE concave shape (See CIGRE 63 document), representing a lightning stroke has been connected to a tower close to the cable.
The case includes the modelling of the different elements of the configuration (cable, spans, arresters...).

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Author: AdminEMTP-RV
Type: Model
Downloaded: 396 times
Date: 2012-06-18

CB_arc_CM

Description:
This is an interesting case of the study of arc-circuit interaction in case of the interruption of a short-line fault.The arc is represented by a composite Cassie-Mayr model and the line is represente... see mored as frequency-dependant.
The case shows the application of black-box arc modeling in the study of kilometric-line fault capability of a 420 kV circuit-breaker. By zooming on the arc current and voltage near current-zero, post-arc current and initial TRV may be visualized in both cases of clearing and thermal failure.

Tag(s): Example, Protection

Author: AdminEMTP-RV
Type: Document
Downloaded: 522 times
Date: 2012-06-18

A Tool for Steady-State and Dynamic Analysis of PV Generation in Low Voltage Grids

Description:
Authors:
Dennetière S., Mahseredjian J., Duvauchelle C., Tounsi B.
This paper describes a tool based on EMTP-RV that simulates the steady-state and the dynamic behavior of photovoltaic (PV)... see more units on a low voltage grid. The tool takes into account load and irradiance curves to evaluate the impact of PV units on the voltage profile along the grid as well as the dynamic behavior of PV inverters. This tool has already been used to analyze and explain undesired disconnections of PV units in an existing system.

Tag(s):

Author: AdminEMTP-RV
Type: Document
Downloaded: 912 times
Date: 2012-06-18

Look what happens without EMTP-RV

Description:
This is a nice video about the switching of a shunt reactor (most probably 500 kV) with a Circuit-Switcher.
>A circuit-switcher is a SF6 load-break swith with no fault current breaking cap... see moreability. The load current, in this case around 150 A, is normally interrupted first by the 2 interrupters and then the disconnect will open to isolate the reactor.
What happened in this video:
1 - During the opening, an external flashover occurs on one of the chamber most probably because of the contamination;
2 - The other chamber can not withstand the whole voltage and reignites internally;
3 - The external flashover vanishes because an arc is established inside;
4 - The disconnect opens on the full load current;
5 - The arc burns freely in the air for some 10 seconds until it is self-extinguished or eliminated by a circuit-breaker operation.

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