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SCHEMES FOR REDUNDANCY BY INFORMATION EXCHANGE BETWEEN RELAYS IN POWER SYSTEM

IP.com Disclosure Number: IPCOM000219438D
Publication Date: 2012-Jun-29
Document File: 4 page(s) / 152K

Publishing Venue

The IP.com Prior Art Database

Related People

IVAN BERNARD FULLER: ATTORNEY

Abstract

The idea of redundancy in protection and control IEDs and their different configurations to achieve higher reliability has been proposed. Three configurations Master-Slave, Slave-Master and Peer-Peer using the IEC61850 GOOSE communication profile are proposed. Here, the main IED used for protection and control is called the master IED and the redundant IED is the slave IED. It is through an IED’s settings the behavior of the IED be controlled or influenced. The startup settings for the applications would be stored in the master IED. The identification of a master or slave (or follower IED in peer-peer case) shall be handled using settings. The slave or follower shall keep a copy of setting file sent by the master or peer (updated using FTP or constructed using slow periodic GOOSE messages). This file shall be updated (as its own settings) by the slave or follower after adequate checks and user confirmations.

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Schemes for Redundancy by Information exchange between relays in Power System

Arinjai Gupta, Ganesh Kulathu, Murali Kandakatla, Pramod Kulkarni, Ravishankar Y A, Shivakumar N R & Sudheer B

Abstract

The idea of redundancy in protection and control IEDs and their different configurations to achieve higher reliability has been proposed.  Three configurations Master-Slave, Slave-Master and Peer-Peer using the IEC61850 GOOSE communication profile are proposed.  Here, the main IED used for protection and control is called the master IED and the redundant IED is the slave IED. It is through an IED’s settings the behavior of the IED be controlled or influenced. The startup settings for the applications would be stored in the master IED. The identification of a master or slave (or follower IED in peer-peer case) shall be handled using settings. The slave or follower shall keep a copy of setting file sent by the master or peer (updated using FTP or constructed using slow periodic GOOSE messages). This file shall be updated (as its own settings) by the slave or follower after adequate checks and user confirmations.

Background

Improving the reliability of power system protection and control IEDs is a constant challenge for utilities and manufacturers. Normally in power systems backup protection is common, the backup operates after a time delay and hence the protected device is subject to fault current until the back- up time. In critical applications like Nuclear power plant and critical substations, the cost of failure of protection and the inherent delay in backup protection would out-weigh the cost of redundancy. Though the idea of using the redundant IED has been explored before, the mechanisms to achieve the same have seldom been effective. Hence the idea of using redundant IEDs and the various configurations used to achieve higher reliability using 61850 based communications has been proposed.

Description

Typically in power system back up protection in Figure 1, if the Relay 3 fails to trip then Relay 1 trips as back-up protection after a set time delay. So in case of back-up protection, the power system is subjected to the fault till the additional back-up delay time.

In the proposed redundancy scheme, in Figure 1, if the Relay 3 fails to trip the redundant Relay3_R which is functioning parallel to the Relay3 will trip immediately without any additional time delay. This improves the reliability of protection and also improves transient stability margin of the power system.

In the redundancy scheme, the same currents and voltages (CT, VT) to be connected to both main and redundant relays.  If the instrument transformers (CT, VT) used is conventional type, it doubles the burden on the conventional instrument transformers.  In this case, SAMU (Stand Alone Merging Unit) can be used to reduce the burden on CTs and VTs as shown in Figure 2.

Figure 1: Backup protection at station B

Figure 2: Information exchange between redundant relays and with me...