J. R. Lucas

Improved simulation models for current and voltage transformers in relay studies

Improved models for current transformers (CT), potential transformers, and capacitive voltage transformers (CVT) for a relay software library are presented. The magnetizing characteristic in each of these transformers is based on the nonlinear power curve formulation of J.R. Lucas (1988). The flux-current loops of the transformer core are self-generated rather than predetermined or based on look-up tables. The results presented show that the models developed for the transformers behave as expected, and agree with reported field investigations. Models for the CT and CVT give acceptable results, including those under remanent conditions and ferroresonant conditions. These models are thus necessary components for relay studies carried out with electromagnetic transient programs whether offline or in real time. >

A computationally efficient MOV model for series compensation studies

The authors describe a computationally efficient model for metal oxide varistors (MOVs) suitable for use in simulation studies of series compensated lines. It can also be used in simulators running EMTP type solutions in real-time since it does not rely on an iterative technique for its implementation. The EMTP program on which this work is based is the version written by Manitoba Hydro and is called EMTDC. The line on which the studies have primarily been based is the 500 kV line from the Dorsey converter station north of Winnipeg to the Forbes substation in Minnesota. The source structure has not been represented in great detail but is adequate for examining the behavior of the MOVs. In addition, the proposed model is inserted in a simulation of a previously published study and shown to give good agreement. >

A workstation environment for assessing relay performance

The authors describe an offline simulation facility for assessing the transient performance of relays. The facility is based on a user-friendly workstation environment whereby input and output information is presented in graphical form, making it easy for the nonexpert to use sophisticated simulation tools to solve problems relevant to choosing and setting relays. This greatly reduces the turnaround time in making design decisions and enhances appreciation of the capability and limitations of the elements in a protection system.<<ETX>>

A low cost partial discharge measuring system for a high voltage laboratory

Failures in high voltage equipment are often caused due to internal faults which cause a local electrical stress concentration in the insulation, known as partial discharge. Thus detection of partial discharge is very important for early detection of insulation failure. This paper presents a low cost design and implementation of partial discharge measuring equipment for a high voltage laboratory. Partial Discharge detection has been carried out using electrical Partial Discharge measurement method with wide band filtering. The simulation of the Partial Discharge measuring system has been carried out for a test object with a void inside. Hardware with a user friendly Graphical User Interface has been implemented and tested. Results obtained are validated against those obtained by other researchers and with available information of commercial equipment.