Woodward GCP-20 Series User Manual

Manual 37128A GCP-20 Series - Genset Control
Page 90/190 © Woodward
Stopping Hysteresis
NOTE
The following Parameter 87 is used to determine stopping hysteresis for single gensets in mains paral-
lel operation, for generators connected to other generators in mains parallel operation, and in isolated
operation in parallel with other gensets. However, the parameter appears only once in this text.
Parameter 87
Hysteresis add-.
on/off op.0000kW
Load dependent start/stop: hysteresis 0 to 9,999 kW
The stop power value of the generator is determined via a hysteresis. The hysteresis
is used to prevent the engine continuously starting and shutting down again.
Mains Parallel Operation (Mains Interchange (Import/Export) Real Power Control with One
Generator)
General
Case 1: Start of the engine
If [P
NT.Setpoint
- P
NT.actual
> P
start
] the engine starts. (a)
Case 2: Stop of the engine
If [P
NT.setpoint
- P
NT.actual
+ P
GN.actual.tot
< P
start
- P
Hyst
] the engine stops. (b)
Example
The power supplied by the mains, which is to be adjusted, is 50 kW. This value is entered into the set point value
screen (see chapter "Controller") as "I0050kW". The generator should be operated with at least 30 kW.
P
NT.setpoint
= -50 kW Incoming/import power has to be entered negative, output/export power positive.
P
star
= 30 kW The minimum power requested by the generator.
P
Hyst
= 10 kW The power hysteresis for stopping.
When inserted into the above-mentioned formula, this means:
Case 1:
The engine starts with the following import mains power: If formula (a) is inverted, this results in
[P
NT.actual
< P
NT.setpoint
- P
start
] ⇒ P
NT.actual
< - 50 kW - 30 kW = -80 kW ⇒ "I0080 kW"
The power supplied by the mains must be at least 80 kW in order for the engine to start. This is then oper-
ated with a minimum power of 30 kW.
Case 2:
The engine stops if it has to supply less than the minimum power minus hysteresis. This is the case with
the following generator power: If formula (b) is inverted, this results in
[P
GN.actual
= stop power engine < - P
NT.setpoint
+ P
NT.actual
+ P
start
- P
hyst
].
[P
GN.actual
< - 50 kW + 50 kW + 30 kW - 10 kW = 20 kW.
If the generator falls below its minimum power minus hysteresis, the engine is stopped. The power im-
ported from the mains therefore remains at the value that is to be controlled until just prior to stopping.
Following stopping, the power supplied by the mains increases to 70 kW.

Woodward GCP-20 Series Specifications

General

Brand	Woodward
Model	GCP-20 Series
Category	Control Unit
Language	English