Alstom MiCOM P54 Series - 5.5 The communication services of MiCOM relays; 5.6 Peer-to-peer (GSE) communications; 5.6.1 Scope

SCADA Communications P54x/EN SC/La4
MiCOM P543, P544, P545 & P546 (SC) 13-31
SC
5.5 The communication services of MiCOM relays
The IEC 61850 communication services which are implemented in the Px40 relays are
described in the Protocol Implementation Conformance Statement (PICS) document, which
is available separately. The PICS document provides the Abstract Communication Service
Interface (ACSI) conformance statements as defined in Annex A of Part 7-2 of the IEC
61850 standard.
5.6 Peer-to-peer (GSE) communications
The impl
ementation of IEC 61850 Generic Substation Event (GSE) sets the way for cheaper
and faster inter-relay communications. The generic substation event model provides the
possibility for a fast and reliable system-wide distribution of input and output data values.
The generic substation event model is based on the concept of an autonomous
decentralization, providing an efficient method allowing the simultaneous delivery of the
same generic substation event information to more than one physical device through the use
of multicast services.
The use of multicast messaging means that IEC 61850 GOOSE uses a publisher-subscriber
system to transfer information around the network*. When a device detects a change in one
of its monitored status points it publishes (i.e. sends) a new message. Any device that is
interested in the information subscribes (i.e. listens) to the data it contains.
Note: * Multicast messages cannot be routed across networks without
specialized equipment.
Each new message is re-transmitted at user-configurable intervals until the maximum
interval is reached, in order to overcome possible corruption due to interference, and
collisions. In practice, the parameters which control the message transmission cannot be
calculated. Time must be allocated to the testing of GSE schemes before or during
commissioning, in just the same way a hardwired scheme must be tested.
5.6.1 Scope
A maximum
of 32 virtual inputs are available within the PSL which can be mapped directly to
a published dataset in a GOOSE message (only 1 fixed dataset is supported). All published
GOOSE signals are BOOLEAN values.
Each GOOSE signal contained in a subscribed GOOSE message can be mapped to any of
the 32 virtual inputs within the PSL. The virtual inputs allow the mapping to internal logic
functions for protection control, directly to output contacts or LEDs for monitoring.
The MiCOM relay can subscribe to all GOOSE messages but only the following data types
can be decoded and mapped to a virtual input:
 BOOLEAN
 BSTR2
 INT16
 INT32
 INT8
 UINT16
 UINT32
 UINT8