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Author: AdminEMTP-RV
Type: Model
Downloaded: 376 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: 184 times
Date: 2012-06-18

Self_Exc_ind

Description:
Simulation case of the self-excitation of induction motors during startup on a series compensated radial line.

This case reproduces the results published in the book of Anderson and Farmer ... see moreentitled 'Series Compensation of Power Systems', PBLSH publisher, 1996.

Although approximate data are used, results compare surprisingly well with the figures in chapter 7.

Tag(s): Motor

Author: AdminEMTP-RV
Type: Model
Downloaded: 193 times
Date: 2012-06-18

TCR1

Description:
Example of single phase Thyristor Controlled reactor using TACS control devices. This circuit reproduces the TCR case presented in the EMTP Workbook volume 4 chapter 6.

Example of single ph... see morease Thyristor Controlled reactor using TACS control devices. This circuit reproduces the TCR case presented in the EMTP Workbook volume 4 chapter 6.

The basic static Var system consists of a static switch in series with an inductor. This is normally called a phase controlled reactor, or Thyristor Controlled Reactor (TCR). The TCR is in parallel with a fixed capacitor. Together they interface with the power system at some interconnection point. The control circuit of the TCR can be divided into three parts. There is the gate pulse generator (GPG), the heart of the control system, a voltage regulator and an interface to the power systems which could be simply a RMS voltage meter.

The purpose of the gate pulse generator is to provide firing pulses to the thyristors. The regulator calculates the conduction angle, ?, which is passed to the gate pulse generator as a control signal. It is the function of the gate pulse generator to generate the correct firing pulses to achieve the requested conduction angle, ?. In this example the gate pulse generator is modeled using TACS control devices.

Tag(s): Power Electronics