Emergency Stop

Sometimes it will be necessary for the turbine to shut down suddenly in response to some safety system trip or because the turbine is requested to stop immediately. This scenario is distinct from normal shutdowns because it is triggered by an emergency situation.

Bladed can trigger a special emergency stop event that can be either handled internally or by a user supplied external logic.

For simulations of type emergency stops, click the Emergency stop button on the Control screen.

Built-In Emergency Stop

To use the built-in logic for emergency stops, select Defined as shown. Note that this option is mainly for legacy projects since it hardwires grid loss and overspeed events to a complete turbine shutdown. Modern turbines may want to attempt a special recovery action like a “ride through” instead. See the safety system for the functionality to model a modern safety system.

If the built-in logic for emergency stops were to be used, it models the safety system’s actions to bring the rotor to a full halt. A traditional safety system of this type will attempt to stop the rotor by feathering the blades to utilise aerodynamic braking and/or the use of a brake within the drivetrain. The triggering of these actions can be either directly on the occurrence of a grid loss (the grid loss trip mode), or by the increase of the rotor speed beyond a certain threshold (the “overspeed” trip mode).

Following parameters need to be selected appropriately:

• Emergency pitch trip mode: Select overspeed if aerodynamic braking is to be triggered by an overspeed, or grid loss if it is to be triggered immediately on loss of load.

• Rotor overspeed trip to start pitching: The overspeed condition which triggers the aerodynamic braking if Emergency pitch trip mode is set to overspeed.

• Emergency pitch rate: the constant pitch change rate which is used following the grid loss or overspeed.

• Final pitch: the final pitch angle. If the emergency pitch rate is negative, the final pitch should be the most negative pitch angle. The initial pitch angle will depend on the running conditions before the stop occurs.

• Emergency shaft brake trip mode: Select overspeed if the shaft brake is to be triggered by an overspeed, or grid loss if it is to be triggered immediately on loss of load.

• Rotor overspeed for trip brake application: The overspeed condition which triggers the shaft brake if emergency shaft brake trip mode is set to overspeed.

• Rotor speed for brake application for parking: when the rotor has slowed down to this value, the shaft brake is applied to bring the rotor to rest if it has not already been applied as a result of grid loss or overspeed.

For this option an emergency stop event can be triggered by:

• Time to begin a stop which is set in the simulation control.

• Grid loss.

• Rotor overspeed.

• Emergency stop button in the safety system screen.

User-Defined Emergency Stop

Alternatively, click Defined by external controller to use a user-defined controller logic to handle an Emergency stop event. There exists a GetControllerState() function in the external controller API to catch the event and an equivalent entry in the swap array controller as well.

In this case the event can be triggered by:

• Time to begin a stop which is set in simulation control.

• Emergency Stop button in the safety system screen.

Note

1. Pitch angles and rates apply also to aileron/flap/airbrake deployment angles. They are ignored if the rotor has no aerodynamic control surfaces.
2. User-defined supervisory control may also be defined in a user-defined controller.

Last updated 15-11-2024