Turbine control unit comprising a thermal stress controller as a master controller

1. A turbine control unit for controlling a turbine, comprising:

a cascade controller having a master controller and an inner controller,

wherein the master controller is a thermal stress controller for the temperature of components which are subjected to thermal stress, and

wherein the turbine control unit is designed to control partial turbines separately.

2. The turbine control unit as claimed in claim 1 ,

wherein the inner controller comprises a turbine controller that controls a turbine power level of each of the partial turbines.

3. The turbine control unit as claimed in claim 2 ,

wherein the turbine controller that controls the turbine power level is designed to generate setpoint values for position controllers which can control the position of an actuating valve for each respective partial turbine.

4. The turbine control unit as claimed in claim 1 , further comprising:

a thermal stress calculation unit that predefines at least one setpoint value to the thermal stress controller.

5. The turbine control unit as claimed in claim 1 ,

wherein the thermal stress controller is designed to ensure for such control of the partial turbines that a desired rise in temperature over time is not exceeded.

6. The turbine control unit as claimed in claim 1 ,

wherein the thermal stress controller is designed to avoid thermal stress which is caused by temperature differences.

7. The turbine control unit as claimed in claim 1 , further comprising:

a temperature sensor associated with each of a plurality of the partial turbines.

8. The turbine control unit as claimed in claim 7 ,

wherein the temperature sensors are mounted on a high-pressure turbine and/or on a medium-pressure turbine.

9. The turbine control unit as claimed in claim 1 ,

wherein the turbine control unit controls the starting of each of the partial turbines.

10. The turbine control unit as claimed in claim 1 ,

wherein the partial turbines comprise a high-pressure turbine, a medium-pressure turbine and a low-pressure turbine.

11. A method for controlling a turbine having a cascade controller comprising a master controller and an inner controller, the method comprising:

sensing by the master controller thermal stress of each of multiple partial turbines, and

transferring individual setpoint values to the inner controller for the partial turbines which are such that undesired thermal stress of each of the partial turbines is avoided.

12. The method as claimed in claim 11 ,

wherein the master controller senses the thermal stress by a rise in temperature over time for a plurality of the partial turbines, and determines the thermal stress arising therefrom,

wherein in the case of excessively high thermal stress in any one of the partial turbines, the respective individual setpoint value is transferred to the inner controller to reduce an increase in power of the respective turbine, in the case of thermal stress within a desired range the setpoint value is transferred in order to be able to maintain the increase in power, and in the case of thermal stress below a threshold value the setpoint value is transferred in order to be able to boost the increase in power.

13. A method for controlling a turbine power plant comprising a high pressure turbine, a medium pressure turbine and a low pressure turbine, the method comprising:

measuring a temperature rise over time in at least the high pressure turbine and the medium pressure turbine;

using the measured temperature rises over time and stored data to calculate in a thermal stress calculation unit an individual thermal stress parameter for each of the high pressure turbine, the medium pressure turbine and the low pressure turbine;

using the individual thermal stress parameters to determine in a master thermal stress controller an individual thermal stress setpoint for each of the high pressure turbine, the medium pressure turbine and the low pressure turbine separately; and

using the individual thermal stress setpoints in an inner turbine control unit to control a power level for each of the high pressure turbine, the medium pressure turbine and the low pressure turbine individually such that power level over time in each of the high pressure turbine, the medium pressure turbine and the low pressure turbine is controlled differently in order to avoid an undesired thermal stress in any of the turbines.

14. The method of claim 13 , further comprising controlling the power levels by controlling with a position controller a respective actuation valve for each of the high pressure turbine, the medium pressure turbine and the low pressure turbine separately.

15. The method of claim 14 , further comprising measuring a position of each of the respective actuation valves separately and using the respective measured positions to determine in the position controller whether a desired position for each valve has been achieved or if further opening or closing of a respective valve is needed.