WOODWARD 2301E Digital Speed Controller

Load Pulse: When a rapid increase in load is detected (such as when a large motor starts), the controller briefly increases fuel output to compensate for the upcoming speed drop.

Load Rejection: When a rapid decrease in load is detected (such as a circuit breaker tripping), the controller briefly reduces fuel output to prevent overspeed.

Generator Breaker Open Pulse: When the circuit breaker is disconnected and the current load is higher than the set value, the fuel instantly drops to zero for a period of time, effectively suppressing the speed rise after load shedding.

Dynamic tuning practice: from start-up to optimization

The goal of dynamic tuning is to find the PID parameters that make the engine stable and respond the fastest. Recommended on-site tuning process based on Zeigler Nichols method:

Preparation steps:

Ensure that the engine is able to run steadily at idle speed. Copy the first set of dynamic parameters to the second set for quick switching in case of instability.

Use the Trend Tool of Control Assistant or analog output (4-20mA corresponding to speed) to record the speed response curve.

Setting steps:

Proportional control only: Set Reset to 0.01 (minimum integral action) and actuator compensation to 0.01 (minimum differential action). Set the window width to 60rpm, the gain ratio to 1.0, and the gain slope to 0.

Find the critical gain Ku: Gradually increase the proportional gain (first adjust the idle gain, then adjust the rated gain), and use the "actuator bump" function (set the bump amplitude to 1-2% in the O menu for 0.1 seconds) to excite the system after each increase. Observe the speed oscillation. Continuously increase the gain until an equal amplitude oscillation (critical stability) occurs, and record the gain value Ku at this time.

Measurement of oscillation period Pu: Measure the time (in seconds) of a complete oscillation period from the trend chart, denoted as Pu.

Calculate initial PID:

Final gain=Ku/1.7

Reset=2/Pu (e.g. when Pu=3.133 seconds, reset ≈ 0.64)

Actuator compensation=Pu/8 (e.g. 3.133/8 ≈ 0.39)

Fine tuning: After entering the calculated value, perform a load step test again (such as adding/subtracting 20% load). If the speed overshoot is too large, increase the reset appropriately (reduce the integration time) or decrease the gain. If the recovery is too slow, reduce the reset.

Adjust the window width to gain ratio: Set the gain ratio to 2.0, then gradually decrease the window width (from 60rpm downwards, decreasing by 10rpm each time), while observing the load step response. When the window width is small enough to cause instability, increase it back to the previous stable value. This function can significantly reduce the speed drop during load transients.

For nonlinear systems such as gas engines, 5-point gain mapping is required. The method is to find stable gains at different load points (unloaded, 25%, 50%, 75%, 100%), and then fill in the corresponding breakpoints and gain values.

Practical troubleshooting: common problems and solutions

The following are typical faults and troubleshooting paths based on the manual and on-site experience summary:

Fault 1: Engine cannot start, actuator does not operate

Check power supply: Is the voltage between terminals 48-49 ≥ 18V? Is the CPU status LED green (if red, it indicates I/O Lock or self-test failure)?

Check speed signal: When starting, is the AC voltage between terminals 25-26 ≥ 1.0Vrms? If it is 0, check the resistance value (about 100-300 Ω) and gap of the MPU.

Check the Start Fuel Limit: Check the Fuel Demand% in the Display Menu. Does it jump to the Start Fuel Limit setting (such as 100%) when starting? If it remains at 0, it may be because the "Close to Run" input (terminal 34) is not closed or the logic is reversed.

Check the coverage of the failed speed signal: If the protection is triggered due to the absence of MPU signal during startup, the discrete input configured as "Failed Speed Override" can be temporarily closed to allow startup.

Fault 2: Engine instability (traveling block)

Fast jitter (>1Hz): The proportional gain is too high. Reduce Rated Prop Gain.

Slow oscillation (<0.5Hz): The reset is too strong (the value is too large). Reduce the Reset value (increase integration time).

Check actuator compensation: If the compensation is too large, the actuator will become overly active. For diesel engines, compensation is usually 0.1-0.2; For carburetor gas engines, 0.3-0.5.

Check speed filter: If there is strong ignition torsional vibration in the engine, the speed filter frequency can be reduced (default 12Hz, adjustable to 8-10Hz).

Fault 3: Uneven load distribution during parallel connection

Check CT/PT phase: Use the "Phase Correction Procedure" in the manual. The most common problem is CT polarity reversal or phase sequence error. Correction can be achieved by temporarily swapping CT terminals and observing load readings.

Calibrate load reading: In Service Menu T, use "KW Input Calibration" to adjust the zero point and gain so that the Generator Out (kW) displayed on the controller is consistent with the external instrument.