Woodward GCP-30 Series User Manual

Manual 37365A GCP-30 Series Packages - Genset Control
© Woodward Page 63/179
Case 5:
An engine start command is issued to the second generator when the monitored mains power reaches a specified
level. Formula D is used as follows:
[(generator rating)(number of closed GCBs) – parallel reserve power] / number of closed GCBs = generator
power level at next start
[(200 kW)(2) – 40 kW] / 2 = 180 kW.
The two generators that are providing power have a total load rating of 400 kW (200 kW x 2). Both generators
combined have an available load of 360 kW (400 kW – 40 kW). The reserve power limit is split equally between
the two generators giving each generator an effective load of 180 kW each. When the individual generator loads
exceed 180 kW, the next generator will be started and brought online to share the load.
Case 6:
An engine stop command is issued to the first generator when the monitored system power falls to a specified
level. Formula E is used as follows:
(number of generators needed for load – 1 generator)(generator rating) – reserve power
– generator hysteresis =
Power level next generator stopped
(3 – 1)(200 kW) – 40 kW – 20 kW = 340 kW(3 – 1)(200 kW) – 40 kW – 20 kW = 340 kW
System power level / number of closed GCBs = individual generator load level
340 kW / 3 = 113.3 kW
The three generators that are providing power have a total load rating of 600 kW (200 kW x 3). Before a genera-
tor can be shut down as the load decreases, the two generators that will remain online must be able to sustain the
remaining load. This requires that the above formula be used to determine the load level that a shutdown com-
mand is issued. According to the calculations above that level is 340 kW. This load is shared equally among the
online generators. To determine the individual generator load levels the shut down power level must be divided
by the number of generators online (340 / 3 = 113.3 kW). When the individual loads for the generators drop be-
low 113.3 kW, a stop command will be issued and a generator will shed its load to the remaining generators,
open its GCB, and shut down.
Case 7:
An engine stop command is issued to the second generator when the monitored system power falls to a specified
level. Formula E is used as follows:
(
number of generators needed for load – 1 generator)(generator rating) – parallel reserve power – generator hys-
teresis = system power level next generator stopped
(2 – 1)(200 kW) – 40 kW – 20 kW = 140 kW.
System power level / number of closed GCBs = individual generator load level
140 kW / 2 = 70 kW
The two generators that are providing power have a total load rating of 400 kW (200 kW x 2). Before a generator
can be shut down as the load decreases, the generator that will remain online must be able to sustain the remain-
ing load. This requires that the above formula be used to determine the load level that a shutdown command is is-
sued. According to the calculations above that level is 140 kW. This load is shared equally among the online ge-
nerators. To determine the individual generator load levels the shut down power level must be divided by the
number of generators online (140 / 2 = 70 kW). When the individual loads for the generators drop below 70 kW,
a stop command will be issued and a generator will shed its load to the remaining generator, open its GCB, and
shut down.
Case 8
:
An engine stop command is issued to the last generator when the monitored system power falls to a specified
level. Formula F is used as follows:
desired mains interchange power level + monitored mains power + minimum load generator –
generator hystere-
sis = mains power level when generator stops
0 kW + 0 kW + 30 kW - 20 kW = 10 kW
The final remaining generator will be taken offline after the load supplied by the generator drops below the con-
figured mains interchange level plus the monitored power at the mains interchange minus the minimum confi-
gured load for the generator minus the generator hysteresis or 10 kW in this case. When the load drops to 10 kW,
the load is shed from the generator to the mains, the GCB is opened, and the generator is shut down. The mains
will now import 10 kW. If the load increases again, the previous steps are repeated.

Woodward GCP-30 Series Specifications

General

Brand	Woodward
Model	GCP-30 Series
Category	Controller
Language	English