Here is the example of real project (IED and signal names are renamed), where the dataset of the GOOSE message is shown on the right, and the subscribing IEDs — on the left.
Here we can see, that not all the signals from the GOOSE are being processed with each device: e.g. Signal1, including its stVal and q are transmitted to each device IED2…IED9.
While the rest of the signals, i.e. Signal2…Signal5, are subscribed by IED2 and IED 3 only.
As an alternative to the taken solution we might have splitted the Dataset of the GOOSE-message into two Datasets and transmit them with two GOOSE-messages as follows:
- GOOSE with Signal1 data attributes only, subscribed by all IEDs.
- GOOSE with Signal2…Signal5, subscribed by IED2 and IED3 only.
Given thet the network is “transparent” (i.e. no network filtering for GOOSE-messages is applied) the proposed approach would result in increased network interface load of all subscribing IEDs, as they would have to process two GOOSE-messages instead of one, but (probably) the application-level load would decrease, due to smaller ammount of signals in each message.
It would be of a great interest for us to get comments from IED developers (taking specific approaches in IEDs into account) on the following questions:
- Given the “transparent” network (i.e. again no network filtering is applied), which approach would result in better pefrormance of IED2…IED3 and IED4…IED9: to have one GOOSE-message with all the signals included in dataset (as made in the project above) or split the data into two GOOSE-messages (as proposed)?
- If network filtering would be enabled and “unsubscribed” traffic would be restricted, would it increase the performance of non-subscribing IEDs dramatically (i.e. in the discussed case the second GOOSE-message, containing Signal2…Signal5 data attributes would reach network interfaces of IED2 and IED3 only) and would it make 2-GOOSE-message solution more advantegeous?
- If the case discribed here is not relevant (due to small amount of signals), then how many signals (approximately) would make it more relevant?