GOOSE load estimations - Arc protection - Auto synchronization - Bay control and measurement - Merging unit - Transformer protection - 2 winding - Feeder protection - Voltage regulation - Capacitor bank protection - Petersen Coil control - Grid automation - Busbar differential protection (high impedance) - Back-up protection - Motor protection - Busbar protection (voltage and frequency) - Transformer protection - 3 winding - Interconnection protection - Generator protection - Power management/Load shedding - IEC 61850 Engineering Guide - REX640 Protection and control - Relion Protection and Control - PCL6 - IEC - ANSI

GOOSE performance classes are defined in standard part IEC 61850-5 Edition 2. For trip signals, there are several performance classes.

P1 = quarter of the electrical network sinus waveform cycle
P2 = in the order of half of the electrical network sinus waveform cycle

For other fast messages, there is one performance class.

P3 = in the order of one cycle of the electrical network sinus waveform

For the medium-speed messages, there is one performance class.

P4 = transfer times under 100 ms

Configuration load calculation ensures that the relay's application configuration is within the allowed limits. GOOSE load estimation is calculated independently and uses the remaining system capacity. The process bus load is handled by hardware. For more information on the configuration load calculation, see the engineering manual.

To have optimal GOOSE performance in the P1...P3 performance classes, several configuration aspects should be considered.

All the above configuration loads are feasible, but in different application types. If the configuration exceeds the above time categories, it is not possible to use it. The tool does not download the configuration to the relay and error message “Increased GOOSE latency detected under heavy load. Configuration changes needed” is shown.

Minimizing the overall configuration load (ACT configuration) since the remaining time is available for GOOSE.

Unused function blocks should be removed.
Minimizing the received and sent GOOSE data set sizes.
- It is optimal to have smaller data sets.
- Each received data set needs to be decoded before the attribute content can be used. Thus all attributes are counted in load estimations. For example, 20 received data sets having 20 attributes results in a 400- attribute load.
- Minimizing the number of measurement values in GOOSE data sets

Designing the station level data flows and bay function allocation.

Good basic understanding of the system data flows helps keeping the concepts clear and minimizes the traffic.
It may be good to use some configurations for collecting and grouping global states. For example, the busbar state is collected in a sectionalizer and sent to other bays.

In REX640, GOOSE load estimations are based on the worst case measured values. The performance class met by the configuration is expressed by information and warning messages. The tool does not produce messages for performance classes above P3.

Table 1. Message examples
Messages	Description
Information messages
Increased GOOSE latency might be detected under heavy load.	P3 performance class requirement may not be met.
Increased GOOSE latency will be detected under heavy load.	50% of the packets do not meet the P3 performance class requirement.
Warning messages
Increased GOOSE latency detected under heavy load. Configuration changes needed.	70% of the packets do not meet the P3 performance class requirement.