Figure 7.1 Power management communication
DEIF network
GENSET
controller 2
GENSET
controller 3
GENSET
controller 1
Genset status
Nominal power
Actual power
Genset status
Nominal power
Actual power
Genset status
Nominal power
Actual power
+
- ÷
×
+
- ÷
×
+
- ÷
×
For this example, the power management rules for the section specify the minimum P available limit.
Each controller calculates:
• Nominal power = ∑ Nominal power for connected gensets in the section
• Consumed power = ∑ Actual power from the connected gensets in the section
• Available power = Nominal power - Consumed power
• Genset priority order
• Genset start
How it works:
1. The controllers each communicate their genset status, genset nominal power, and the genset power that the controller
measures, using the DEIF network.
2. Each controller does the power management calculations.
3. If the controllers calculate that the load-dependent start limit (P available limit) is exceeded, then the controller for the next
genset in the priority order starts that genset.
Protections
Most power management failures activate the standard controller alarms.
Only the alarms that are specific to power management are described in this chapter.
Finding alarms example
The power management system may fail to de-load a GENSET controller's generator breaker. The GENSET controller
then activates the GB de-load failure alarm.
This alarm is described in the Breakers chapter, under Synchronisation and breaker protections.
7.1.2 Power management functions
These power management functions apply to the GENSET controller, and also to the other controllers working together as a system.
Functions
Reliable power
• Blackout prevention
◦ Precautionary genset start (either automatically or by operator action)
◦ De-load before opening breakers
DESIGNER'S HANDBOOK 4189340911K UK Page 209 of 521
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