GE UR series, Manual

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CHAPTER 3: IEC 61850 COMMUNICATION OVERVIEW
UR SERIES – COMMUNICATIONS GUIDE 3-7
3
Figure 3-3: IEC 61850 DataSets
3.1.4 TxGOOSE
GOOSE is a service for communicating trip and blocking signals between IEDs. It is expected to be executed in the order of
three milliseconds for Type 1A "Trip" messages within a substation. Publishing of each GOOSE message is controlled by a
control block in the information model of the publishing device, which since UR 7.30 is represented by a TxGOOSE element.
Each GOOSE message includes the values of all of the members of the dataset to which it is configured, and a number of
fields that can be used by the subscriber to identify the particular GOOSE message it subscribes to. The identification fields
are as follows:
•
Destination MAC address — A multicast address that selects the set of destination IEDs
• Source MAC address — A globally unique identification of the publisher
• APPID — A number that is recommended by the standard to be unique within the system
• gocbRef — A reference to the control block object that controls message publishing
• datSet — A reference to the dataset whose members are published
• goID — A string that allows a user to assign an identification to the GOOSE message
• confRev — Configuration revision number to identify changes affecting message content
• ndsCom — A Boolean flag that indicates the publisher needs to be commissioned
• numDatSetEntries — The number of members in the dataset
To facilitate rapid processing in both the publisher and subscriber, the MMS/TCP/IP stacks are bypassed; GOOSE messages
interface directly to the Ethernet layer. To avoid the publisher having to compose and send sequentially individual
messages to each subscriber, multicast addressing is used whereby the network copies each transmitted GOOSE
messages to all subscribers on the same VLAN. Finally, to avoid the long delays that handshaking type protocols can
introduce when a packet is lost, GOOSE instead employs a scheme whereby messages encoding a change of state are
repeated several times; if the first event message is lost, the closely following repetition gets through.
The figure shows the timing of GOOSE transmissions.