Woodward 2301D, Инструкция по установке и эксплуатации, Страница: 84 / 130

2301D/2301D-EC Digital Control Manual 26247
76 Woodward
22. Figure 5-6 shows results of ultimately increasing Gain Ratio from 1.0 to 3.0
and decreasing Window Width from 60 rpm to 5 rpm. Overall peak rpm has
been reduced approx 30 rpm. The fuel demand is steeper with little
overshoot and roll-off. The speed roll-off is extended slightly by the Window
Width and Gain Ratio settings. This is normal.
23. Begin the Window Width and Gain Ratio adjustment process by increasing
the Gain Ratio from 1.0 to 2.0, then reduce the Window Width from 60 rpm in
10-rpm increments. Actuate an actuator bump or load on and load off step
after each adjustment and observe the change in peak engine speed.
Initially, the window will be too wide to cause any change in peak speed.
Eventually a reduction will be observed. Be prepared to first reduce the Gain
Ratio, or second increase the Window Width, if severe instability occurs due
to cycling through the low gain region. Do not attempt smaller Window Width
settings if this occurs. It may be useful to set the alternate (1st or 2nd)
dynamics to produce a stable engine speed and to switch to these dynamics
should severe instability occur while setting Gain Ratio and Window Width.
Otherwise, continue the Window Width reduction and actuator bump
response down to 10 rpm, and then reduce to 5 rpm. Reductions below 5
rpm are not recommended. Increase the Gain Ratio as needed to obtain the
desired response. The objective is to set the smallest Window Width with the
highest Gain Ratio without going unstable. If the Gain Ratio setting that
causes severe instability is known, then the final setting should not be more
than half of this amount.
24. Eventually a point is reached where no further improvement is possible. The
fuel demand overshoot should be minimal. Reduce the Gain or Gain Ratio as
needed to reduce the fuel demand overshoot.
Gain Slope and Gain Break point Adjustments
25. Gain Slope is an adjustment that increases gain as load (fuel demand)
increases. This adjustment should not be changed from 0.0 until the
previously described adjustments have been made. While it is possible to set
a negative Gain Slope which decreases gain as load increases, it is
considered unnecessary and not recommended.
26. The objective of these adjustments is to add gain at high engine loads to
improve transient load response. If the transient load response is already
acceptable, no adjustments are needed. Otherwise proceed as follows:
27. Set the Gain Break point equal to the no-load minimum speed fuel demand.
The actual fuel demand minus the Gain Break point setting is multiplied by
the Gain Slope to add gain when load increases. When the actual fuel
demand is at no-load, the difference is zero, therefore zero gain is added at
no-load.
28. Set Gain Slope while the engine is operating at or near rated load. Gradually
increase the Gain Slope in 0.5 increments, and bump the actuator or make a
step load change to measure the transient response. Continue this process
until the desired transient load response is achieved or excessive instability
occurs. Should excessive instability occur, reduce the setting to one-half of
the setting that produced this instability.