Technical Presentations

VFTO Induced TGPR Analysis for 400kV GIS Substation856

Abstract
Transient enclosure voltage (TEV) also known as Transient ground potential rise (TGPR) is a special case of VFTO. This phenomenon refers to short rise time, short duration high voltage transient which... see more appear on earthed enclosure of GIS. This is mainly through the coupling of internal transients on conductor refracted to the enclosure at enclosure discontinuities such as air terminations, insulated flanges at GIS/Cable interfaces and some current transformers. Primarily disconnector switch operations are causes of VFTO and SF6-Air bushing seems to be the most significant source of TEV.

Observation of sparking between grounded enclosure and support structure, failure of protective devices, inadvertent operation of relays etc are common malfunction of TEV. Despite proper grounding this phenomenon indicates presence of high potentials on GIS enclosures which raises the issue of equipment protection, migration of these transients to adjacent equipment and shock hazards.

TEV in 400kV GIS substation due to “disconnector switch operation” was studied and simulations performed for GIS model with the equivalent resistance of ground grid, resistance and inductance of grounding strip using EMTP. The presentation summarizes the results of study needed for a 400kV GIS substation in India to ascertain VFTO induced TGPR level. The study was carried out by modeling all GIS equipment, enclosure in EMTP and careful consideration of grounding system model. The results of the study were analyzed to decide on the requirement of mitigation methods to ensure the permissible level of TEV.

Tag(s): gis, vfto, very fast transient

EMTP Development Roadmap: PSS/E Import Tool in EMTP 4.2830

Abstract
1. Custom device usage
- New option which allows to import a user-defined device
- Scripts may be called to process the parameters of the RAW, SEQ and DYR files
- The user customer devi... see moreces file section provides the interface

2. Import only specific part of a grid
- This new option allows user to import only specific parts of the RAW file
- PSS/E is required to use this option

Tag(s): EMT simulation, PSSE, grid, import tool

POWERGRID experience with EMTP793

Abstract
To meet the increasing power demand, a number of extra high voltage (EHV) transmission lines is being added to the power system network, which enhances the complexity of power system network. It is es... see moresential duty of power engineer to fulfill the growing demand ensuring the reliability, stability & security of GRID. Transient simulation tools like EMTP play a vital role to provide the flexibility to power engineer for simulating/studying the various case scenarios which couldn’t be simulate in physical power system.


Such tools eventually help power engineer to build a sustainable and secure GRID. In POWERGRID, being a central transmission utility, various studies are being carried out to arrive the technical particular of new transmission system and optimize or fine tuning of existing system. Some of them i.e. Transient Recovery Voltage (TRV) study of 1200kV Transmission network, Smart Power from insulated earth wire of EHV transmission line and 1200kV Transformer Inrush current study are discussed in presentation. 1200kV National Test Station was established & successfully charged along with the transmission line in state of BINA in India.


TRV study was carried out for assessment of various test duties of 1200kV Circuit Breaker. Presentation cover the detailed discussion of 1200kV TRV study and a brief about the facilities like HIL, HVDC control Replica setup, STATCOM replica setup available at Powergrid Advanced Research and Technology Centre (PARTeC).

Frequency and Voltage Data Processing789

Abstract
The complexity of an active distribution system with distributed generation (DG) is increasing day-by-day. Therefore, a reliable protection system is very necessary to satisfy customer demand. Apart f... see morerom main grid supply, active sources are also available near load centers due to which traditional protection schemes fails to function properly.

The magnitude of fault current during grid connected mode of microgrid, is much higher than islanded operation. Therefore, in most of the previous works, overcurrent protection crashes if its pickup current value is not changed when microgrid is shifted to islanded mode. In this work, the current, voltage and frequency data sampled through PMU is processed to protect the system in both the operating modes. A centralized protection scheme is employed that takes frequency data and voltage phasor to differentiate between islanding and fault condition. Further, it detects the faulted feeder and sends trip command to respective relays within a tolerant time.

This method is devised to work as backup protection when main utility grid is available. However, it can work as a primary protection during islanded mode, when local overcurrent relay fails to operate due to settings based on grid connected mode. A standard IEEE 15 bus system modeled in EMTP is taken as test system for every analysis.

Development of a benchmark on EMTP for the test of grid forming power electronic converters785

Abstract
In the next years, the grid forming control will become a reality in the transmission grid. This a major milestone for the grid in order to be able to integrate even more power electronic converters a... see morend it represents also a major challenge. For doing so, the TSO will need to develop a bench mark to test the behavior of this new types of control. This presentation gives a first proposal of benchmark and give some example of the test on several types of grid forming controls. All the simulation model are developed on EMTP.