초록 ▼

The aim of the invention is to improve a method for the primary control so that reserve power that is practically completely available for the effective frequency boost within seconds is available also in the stem turbine part of a gas/steam turbine installation. To this end, the pressure stage is o

The aim of the invention is to improve a method for the primary control so that reserve power that is practically completely available for the effective frequency boost within seconds is available also in the stem turbine part of a gas/steam turbine installation. To this end, the pressure stage is operated with a control valve (6, 7, 8) that is throttled to such an extent that a frequency boost power reserve is built up. Said power reserve is used for frequency boosting in the event of an underfrequency by correcting the desired value depending on the underfrequency. Said corrected value corresponds to an effective area of the flow that is increased vis-?-vis the throttled condition of the control valve (6, 7, 8) and acts on the effective area of flow of the control value (6, 7, 8) with an impressed signal that approaches zero after a predetermined time. Said signal is chosen in such a manner that, despite the correction of the desired value, a stable operative condition is maintained in accordance with the response behavior of the gas/steam turbine installation to the increased effective area of flow.

대표청구항 ▼

1. A control method for a combined gas and steam turbine installation, having a gas turbine part and steam part with at least one pressure stage whose working steam is generated by at least one waste-heat boiler fed with waste heat from the gas turbine part and whose control valve passage cross sect

1. A control method for a combined gas and steam turbine installation, having a gas turbine part and steam part with at least one pressure stage whose working steam is generated by at least one waste-heat boiler fed with waste heat from the gas turbine part and whose control valve passage cross section is adjusted by a control system, whose required value is controlled by use of a control parameter, relating to power, of the pressure stage, comprising:operating the pressure stage with a control valve throttled in such a way that a frequency-support power reserve is built up which, in the case of under-frequency, is used for frequency maintenance by a required value correction being formed which is determined by the amount by which the frequency is too low, wherein the required value correction corresponds to an increased passage cross section relative to the throttled condition of the control valve and acts, using an applied signal decaying with time, on the passage cross section of the control valve; and dimensioning the signal decaying with time in such a way that, taking account of the response behavior of the gas and steam turbine installation to the increased passage cross section, a stable operating condition is ensured despite required value correction. 2. The method as claimed in claim 1, wherein the control parameter relating to power is the upstream pressure present in the region of the control valve, the upstream pressure being determined by measuring the steam throughput and converting it with the aid of a modified sliding pressure characteristic, which is characteristic of the pressure stage and corresponds to a throttled control valve.3. The method as claimed in claim 1, wherein the signal decaying with time is at least one of a square wave signal and a decaying signal which decays with a time constant, at least one of the time constant and the signal shape of the decaying signal being a model for the combined gas and steam turbine installation.4. The method as claimed in claim 3, wherein the signal decaying with time corresponds to a D?Tn model function for the combined gas and steam turbine installation as follows: where TD is a lead time constant, s is the corresponding Laplace operator and Tn is the corresponding time constants. 5. The method as claimed in claim 3, wherein at least one of the time constant and the length of the square wave signal is between 10 and 200 seconds.6. The method as claimed in claim 1, wherein block power control of the combined gas and steam turbine installation takes place and wherein the required value correction, in particular with an applied signal decaying with time, is additionally processed in an inhibit circuit of the block power control system which inhibits correction of the unit power which counteracts the power change to the pressure stage, or to the steam turbine part, on the basis of the required value correction, in particular with an applied signal decaying with time.7. The method as claimed in claim 1, wherein a determination of the pressure variation and of the mass flow variation takes place in the pressure stage and, in the case of opposition between the parameters, the respective direction, of the required value change, which counteracts the tendency of the control parameter is inhibited.8. The method as claimed in claim 2, wherein the signal decaying with time is at least one of a square wave signal and a decaying signal which decays with a time constant, at least one of the time constant and the signal shape of the decaying signal being a model for the combined gas and steam turbine installation.9. The method as claimed in claim 8, wherein the signal decaying with time corresponds to a D?Tn model function for the combined gas and steam turbine installation as follows: where TD is a lead time constant, s is the corresponding Laplace operator and Tn is the corresponding time constants. 10. The method as claimed in claim 4, wherein at least one of the time constant and the length of the square wave signal is between 10 and 200 seconds.11. The method as claimed in claim 1, wherein block power control of the combined gas and steam turbine installation takes place and wherein the required value correction with an applied signal decaying with time, is additionally processed in an inhibit circuit of the block power control system which inhibits correction of the unit power which counteracts the power change to at least one of the pressure stage and to the steam turbine part, on the basis of the required value correction.12. The method as claimed in claim 1, wherein block power control of the combined gas and steam turbine installation takes place and wherein the required value correction with an applied signal decaying with time, is additionally processed in an inhibit circuit of the block power control system which inhibits correction of the unit power which counteracts the power change to at least one of the pressure stage and the steam turbine part, on the basis of an applied signal decaying with time.13. The method as claimed in claim 1, wherein block power control of the combined gas and steam turbine installation takes place and wherein the required value correction is additionally processed in an inhibit circuit of the block power control system which inhibits correction of the unit power which counteracts the power change to at least one of the pressure stage and to the steam turbine part, on the basis of an applied signal decaying with time.14. A control method for a combined gas and steam turbine installation, having a gas turbine part and steam part with at least one pressure stage, whose control valve passage cross section is controlled by use of a control parameter, relating to power, of the pressure stage, comprising:throttling the control valve, to operate the pressure stage, such that a frequency-support power reserve is built up; using, in the case of under-frequency, the frequency-support power reserve for frequency maintenance; determining a required value correction based upon an amount by which the frequency is too low, wherein the required value correction corresponds to an increased passage cross section relative to the throttled condition of the control valve and acts, using an applied signal decaying with time, on the passage cross section of the control valve; and dimensioning the signal decaying with time in such a way that, taking account of the response behavior of the gas and steam turbine installation to the increased passage cross section, a stable operating condition is ensured despite required value correction. 15. The method as claimed in claim 14, wherein the control parameter relating to power is the upstream pressure present in the region of the control valve, the upstream pressure being determined by measuring the steam throughput and converting it with the aid of a modified sliding pressure characteristic, which is characteristic of the pressure stage and corresponds to a throttled control valve.16. The method as claimed in claim 14, wherein the signal decaying with time is at least one of a square wave signal and a decaying signal which decays with a time constant, at least one of the time constant and the signal shape of the decaying signal being a model for the combined gas and steam turbine installation.17. The method as claimed in claim 16, wherein the signal decaying with time corresponds to a D?Tn model function for the combined gas and steam turbine installation as follows: where TD is a lead time constant, s is the corresponding Laplace operator and TD is the corresponding time constants. 18. The method as claimed in claim 16, wherein at least one of the time constant and the length of the square wave signal is between 10 and 200 seconds.19. The method as claimed in claim 14, wherein block power control of the combined gas and steam turbine installation takes place and wherein the required value correction, in particular with an applied signal decaying with time, is additionally processed in an inhibit circuit of the block power control system which inhibits correction of the unit power which counteracts the power change to the pressure stage, or to the stream turbine part, on the basis of the required value correction, in particular with a signal decaying with time.20. The method as claimed in claim 14, wherein a determination of the pressure variation and of the mass flow variation takes place in the pressure stage and, in the case of opposition between the parameters, the respective direction, of the required value change, which counteracts the tendency of the control parameter is inhibited.