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Manual 35018V1
505XT Digital Control System for Steam Turbines
Woodward
64
Figure 3-10. Speed Control Functional Diagram
Speed PID Operational Modes
The Speed PID operates in one of the following modes, depending on configuration and system
conditions:
1. Speed
Control
2. Frequency
Control
3. Unit Load Control (droop)
Turbine inlet valve position (505 LSS position) control
Generator Load control
When not programmed for generator applications, the 505 Speed PID operates in a Speed control mode
at all times. When programmed for generator applications, the state of the generator and utility tie
breakers determine the operational mode of the Speed PID.
When the Generator breaker contact is open, the Speed PID operates in a Speed control mode.
When the generator breaker is closed and the utility tie breaker is open, the Frequency control
mode is selected.
When both the generator and utility tie breakers are closed, a Unit Load control mode is selected.
Speed Control
While in the Speed Control mode, the Speed PID will control a turbine at the same speed or frequency
regardless of the load it is supplying (up to the unit’s load capability). With this configuration, no form of
droop or second controlling parameter (bias logic) is used by the PID for stability or control.
The following Speed PID mode descriptions are based on the 505 program’s default settings. For
information on how to change the 505’s defaulted breaker logic, refer to Volume 2 of this manual. All
pertinent speed control parameters are available through Modbus communications. See Chapter 6 for a
list of all Modbus parameters.
Frequency Control
The following Frequency Control mode descriptions are based on the 505 program’s default settings. For
information on how to change the 505’s defaulted breaker logic, refer to Volume 2 of this manual.
Содержание 505XT
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