SDMO R 340 U, User And Maintenance Manual

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Principle of coupling in normal operation
Coupling in normal operation enables all the generating sets to be coupled (in voltage and frequency) to a busbar supplied
by a generating set designed as master at the output.
A number (1 to 15) is assigned to each Kerys. This number serves solely to establish the IP address of each Kerys for
communication by Ethernet and loading the programs.
A second number (from 1 to 15) is also assigned to each Kerys and defines the priority.
Example: let us assume a plant of 8 generating sets
Gen set 1 2 3 4 5 6 7 8
Priority 08 07 06 05 04 03 02 01
The numbers on the first line enable the IP address of each Kerys to be allocated. The numbers on the second line define
the priority.
Therefore Kerys no. 8 with priority 01 is considered to be the master generating set and closes its flow first. The other
generating sets then synchronise one by one to the central busbar, transmitting the information on voltage, frequency and
phase difference to this busbar (see sketch).
CB1
GS1
U1
CB2
GS2
U2
CB3
GS3
U3
Busbar U
Example for 3 GSs:
• DJ1 (Circuit breaker 1) is closed, the voltage is present on the busbar.
•
Kerys 2 analyses the differences between U2 and U of the busbar before coupling.
• Kerys 3 analyses the differences between U3 and U of the busbar before coupling.
Each Kerys, independently of its neighbour, will close its discharge on the central busbar.
Wattmetric control
The wattmetric control is used when two generating sets are coupled. It provides optimum management of the number of
generating sets operating by constantly analysing the power required by the user.
Let us take the example of a power plant of 4 x 600 kW generating sets.
The threshold setting screen (1-7-3-3) supplies the following data:
Threshold 1 GS => 2 GS 75% 450 kW Threshold 2 GS => 1 GS 30 % 360 kW
Threshold 2 GS => 3 GS 75% 900 kW Threshold 3 GS => 2 GS 30 % 540 kW
Threshold 3 GS => 4 GS 75% 1350 kW Threshold 4 GS => 3 GS 30 % 720 kW
The maximum available power is 600 x 4 = 2400 kW. Assuming that a single generating set is operating, we will have the following
sequence in the case of linear progression of the load.
When the power required by the application reaches 75% of the power of the generating set in operation (GS at priority 01), i.e.
450 kW, the second GS (at priority 02) is started and is synchronised with GS 1. Its flow is then closed.
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