JP3703872B2 - gas turbine - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a gas turbine for reducing an overspeed ratio generated during a transient such as a load interruption in a gas turbine system or a combined cycle system used for power generation or the like.
[0002]
[Prior art]
Stopping power supply for a long time due to a power plant accident has a high social impact, and in a situation such as a turbine runaway, it causes a large-scale fire and equipment damage. Even so, a highly reliable facility that can maintain a healthy state is required. For example, when an accident on the power transmission system occurs due to lightning or the like, the power plant is instantaneously disconnected from the power transmission system, and the power supply is momentarily interrupted (load interruption) to protect the power transmission system. Therefore, the turbine and the generator are released from the load of the transmission system that suppresses the speed, and try to run away, but the overspeed reduction device in the power plant reduces the overspeed and keeps it at the no-load rated speed, and then the transmission system Power supply must be started immediately after recovery.
[0003]
FIG. 9 shows a configuration of equipment in a gas turbine or a combined cycle system. The gas turbine includes a compressor 1, a combustor 2, and a turbine 3 (in the combined cycle, a steam turbine 4 is further coupled on the same shaft), and drives a generator 5.
[0004]
The gas turbine is operated by controlling the intake air amount by the inlet guide vanes 6 and by controlling the fuel input amount by the fuel control valve 7. The speed is controlled by a speed signal detected by the speed detector 8 , the compressor discharge air pressure is controlled by a signal detected from the compressor discharge pressure detector 9 , and the turbine exhaust gas temperature is the exhaust gas temperature. It is controlled by the signal detected by the detector 10.
[0005]
FIG. 10 shows the contents of a conventional gas turbine overspeed reducing device. The upper part of FIG. 10 shows the governor control contents for narrowing down the fuel control valve 7 when the speed is excessive, reducing the input fuel flow rate, and controlling the speed to the rated speed. The lower part of FIG. 10 shows the control content of the inlet guide vane 6.
[0006]
The turbine actual speed signal (TNH) detected by the speed detector 8 is compared with a turbine rated speed signal (Nset) which is a control set value by a subtractor 11, and if the actual speed differs from the rated speed, A certain speed increment is determined as a signal (ΔN). The function generator 12 generates a fuel control valve opening increment signal (ΔFSR) from the speed increment signal (ΔN), and the adder 13 adds this (ΔFSR) to the current fuel control valve opening (GCV). A fuel control valve opening command signal (FSR) is generated and the fuel control valve 7 is driven.
[0007]
On the other hand, the compressor discharge pressure signal (PCD) detected by the compressor discharge pressure detector 9 is detected by the exhaust gas temperature detector 10 after the exhaust gas temperature set value (Tset) is obtained by the function generator 14. The difference from the actually measured exhaust gas temperature signal (Tex) is calculated by the subtractor 15, and the temperature increment is obtained as the signal (ΔT). The function generator 16 generates an inlet guide blade opening increment signal (ΔIGV) from the temperature increment signal (ΔT), and the adder 17 adds this (ΔIGV) to the current IGV opening (IGV) to obtain an intermediate value. The selector 18 makes the IGV set opening (IGVset) within the range from the IGV maximum set opening (IGVmax) to the IGV minimum set opening (IGVmin), and this signal generates the inlet guide blade opening command signal (IGV). The inlet guide vane 6 is driven. At the time of load interruption, the power plant is disconnected from the power transmission system, and the speed of the gas turbine increases rapidly. At this time, by gradually closing the fuel control valve 7, the compressor discharge pressure decreases and the exhaust gas temperature decreases. . The exhaust gas temperature set value (Tset) is maintained at a high value by decreasing the compressor discharge pressure signal (PCD), while the temperature increment signal (ΔF) becomes a negative value by decreasing the actually measured exhaust gas temperature (Tex). The inlet guide blade opening increment signal (ΔIGV) becomes a negative value, and the inlet guide blade 6 is gradually closed.
[0008]
[Problems to be solved by the invention]
At the time of load interruption, the power plant is disconnected from the power transmission system, and the speed of the gas turbine increases rapidly. At this time, it is desirable that the fuel control valve 7 be narrowed down instantaneously to reduce the input energy instantaneously. However, in the conventional overspeed reduction device, the turbine speed is detected by the speed detector 8 and the difference from the rated speed is detected. Thus, the fuel control valve 7 is gradually stopped. That is, in the prior art, since it takes time to narrow down the fuel control valve 7 to the equivalent of the no-load rated speed after the occurrence of load interruption, there is a problem that the speed is likely to increase depending on the amount of fuel (energy) input during that time.
[0009]
Further, in the conventional overspeed reducing device, the inlet guide vane 6 is gradually closed when the load is interrupted. However, closing the inlet guide vane 6 means that the air flow rate in the compressor 1 is reduced. As a result, the power required for the compression is reduced and the speed is not easily lowered, and there is a problem that the high speed state is maintained for a long time. When a driving machine such as a steam turbine 4 is further added in the combined cycle, the above-mentioned problems become more remarkable, and in consideration of recent progress in gas turbine high temperature technology, it is compared with an increase in equipment capacity. However, the amount of increase in drive energy is large, and a large amount of power is generated in a small-capacity facility. With the current technology, it is impossible to reduce the increase in speed when the load is interrupted.
[0010]
The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a gas turbine that can reduce a speed increase value and can quickly return to a rated speed.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problem, the gas turbine according to the present invention includes guide vanes for adjusting the amount of air sucked into the compressor , and operates with the speed controlled to the rated speed. A speed detector for detecting an actual speed of the gas turbine, and when the actual speed detection value in the speed detector exceeds the rated speed, the inlet guide vane is controlled according to the actual speed detection value. A function generator that outputs an open signal, and a controller that drives the inlet guide vane based on the open signal of the inlet guide vane from the function generator .
[0012]
Further, as described in claim 2, the gas turbine according to the present invention is connected between the discharge portion of the compressor and the exhaust portion of the turbine, and is provided with a pipeline for extracting compressed air. And a control valve that is opened when the load is shut off and flows the compressed air to the exhaust part of the turbine.
[0013]
[Action]
In the gas turbine according to claim 1, when an increase in speed is detected by the speed detector, an opening signal of the inlet guide vane is output from the function generator by the increase function, and the amount of intake air increases to increase the compressor. Drive power increases. For this reason, the braking force of the shaft increases, and the above speed can be reduced to the rated speed at an early stage.
[0014]
In the gas turbine according to claim 2 , when the load is cut off, the control valve on the pipe is opened, and the compressed air is extracted from the discharge part of the compressor and flows to the discharge part of the turbine. For this reason, the amount of air passing through the compressor is increased, the braking force of the shaft is increased, and the increased speed can be reduced to the rated speed earlier.
[0015]
【Example】
The present invention will be described below with reference to the drawings. In addition, in order to avoid duplication of this invention, the same location as the past is attached | subjected and shown, and the detailed description is abbreviate | omitted.
[0016]
FIG. 1 shows a gas turbine according to a first embodiment of the present invention. In the figure, reference numeral 8 denotes a speed detector, and a turbine actual speed signal (TNH) from the speed detector 8 is a turbine actual speed signal. A function generator 21 having a relationship between the speed and the speed setting (IGV) is input. The function generator 21 outputs an inlet guide blade set value signal (IGVn: speed setting IGV). . The inlet guide blade set value signal (IGVn) is input to the high value selector 22 together with the inlet guide blade set value signal from the intermediate value selector 18 of the conventional inlet guide blade control device. The opening degree of the inlet guide vane 6 is controlled by the IGV set opening degree (IGVset) output from the high value selector 22.
[0017]
The relationship between the turbine actual speed (TNH) and the speed setting IGV (IGVn) in the function generator 21 is, for example, a minimum value (minimum inlet guide blade opening) up to a speed of 102%, and a linear function above that. The set value is increased and set to a maximum value (maximum inlet guide blade opening) at 106% or more.
[0018]
Next, the operation of this embodiment will be described.
[0019]
When load interruption occurs and the speed increases, the turbine actual speed signal (TNH) detected by the speed detector 8 increases, the speed setting IGV signal value output from the function generator 21 increases, and a speed of 106% If it exceeds, it becomes the maximum value.
[0020]
On the other hand, since the signal value output from the intermediate value selector 18 of the conventional inlet guide vane control device decreases, the high value selector 22 selects the speed setting IGV signal value from the function generator 21 and enters the inlet. The guide vanes are fully opened, the braking force of the shaft is maximized, and the speed increase is reduced.
[0021]
If the speed decreases to 106% or less, the speed setting IGV signal value from the function generator 21 decreases in proportion to the speed, so that the inlet guide vane 6 is closed, and the speed setting IGV is below 102% speed. The signal becomes the lowest and returns to the original no-load rated speed equivalent opening.
[0022]
The effect of the present embodiment will be described with reference to FIG. In the figure, the horizontal axis shows the elapsed time after the load is cut off, the upper part shows the opening degree of the inlet guide blade, and the lower part shows the change in speed.
[0023]
In the figure, the broken line indicates an example of a phenomenon in the prior art, and the solid line indicates an effect in the embodiment of the present invention. In the prior art, after the load is cut off, the temperature of the exhaust gas decreases and the difference from the set value increases, so that the opening degree of the inlet guide blade shifts to the closing operation, and finally reaches the minimum opening degree after a few seconds. On the other hand, according to the present invention, as the speed increases, the opening degree of the inlet guide vane shifts to the opening operation and becomes fully open when it is 106% or more. For this reason, as shown in the lower figure, the peak value of the speed is reduced, and it becomes possible to return to the rated speed more quickly.
[0024]
FIG. 6 shows a first reference example of a gas turbine, which will be described below.
[0025]
In FIG. 6 , reference numeral 5 denotes a generator, and the generator output (Load) from the generator 5 is supplied to the function generator 31 having a relationship between the generator output (Load) and the standard GCV opening (GCVs). It is supposed to be entered. The standard GCV opening signal (GCVs) output from the function generator 31 is input to the calculator 32 to obtain a difference (ΔGCV) from the GCV actual opening (GCV), and this difference (ΔGCV) is The comparator 33 compares with the GCV opening deviation allowable amount (K). The output signal a from the comparator 33 is inputted to the signal generator 34.
[0026]
The signal generator 34 is also supplied with a maximum value (100%) signal b and a no-load rated speed equivalent GCV opening command value (FSRNL). The signal generator 34 When the difference (ΔGCV) deviates from the GCV opening deviation allowable amount (K), the no-load rated speed equivalent GCV opening command value (FSRNL), and when it does not deviate, the maximum value ( 100%) is output as the output signal d. This output signal d is input to the low value selector 35 together with the output signal from the adder 13 of the conventional governor control device, and the fuel is generated by the GCV opening command (FSR) output from the low value selector 35. The opening degree of the control valve 7 is controlled.
[0027]
The relationship between the generator output (Load) and the standard GCV opening (GCVs) in the function generator 31 is set, for example, as a linear function rising to the right.
[0028]
Next, the operation of this embodiment will be described.
[0029]
If load interruption occurs, the generator output (Load) becomes zero, and the standard GCV opening signal (GCVs) from the function generator 31 becomes the minimum value. On the other hand, since the GCV actual opening (GCV) is a large value before the load is interrupted, it exceeds the GCV opening deviation allowable amount (K), and the input value to the low value selector 35 is instantaneously the no-load rated speed. The equivalent GCV opening command value (FSRNL) is obtained, the fuel control valve 7 starts the rapid closing operation, and the GCV actual opening (GCV) becomes the minimum value (FSRNL) in the function generator 31. Thereby, the GCV opening deviation amount (ΔGCV) becomes equal to or less than the GCV opening deviation allowable amount (K), the input value to the low value selector 35 becomes the maximum value, and the low value selector 35 performs the conventional governor control. The signal value is adopted.
[0030]
FIG. 7 shows a second reference example of the gas turbine, which will be described below.
[0031]
In FIG. 7 , reference numeral 41 denotes a generator breaker. The opening / closing operation of the generator breaker 41 is detected by the detector 42 and the generator breaker 41 is opened (load interruption). The signal e is output from the detector 42. The signal e is input to the signal generator 43. The signal generator 43 outputs a signal a that is ON only for one shot when the signal e is input.
[0032]
This signal a is input to the signal generator 44 together with the signal b of the maximum value (100%) and the signal c of the GCV opening command value (FSRNL) corresponding to the no-load rated speed. From 44, the maximum value (100%) is output as the output signal d when the signal a is OFF, and the no-load rated speed equivalent GCV opening command value (FSRNL) is output when the signal a is OFF. The output signal d is input to the low value selector 45 together with the output signal from the adder 13 of the conventional governor control device, and is output by the GCV opening command (FSR) output from the low value selector 45. The opening degree is controlled.
[0033]
The no-load rated speed equivalent GCV opening command value (FSRNL) signal c is input to the signal generator 46 together with the GCV actual opening (GCV), and an output signal from the signal generator 46 is output. f is input to the signal holding circuit 47. Thus, when the signal generator 44 generates a no-load rated speed equivalent GCV opening command value (FSRNL), the signal is held until the GCV actual opening (GCV) becomes the same as the signal c. It has become.
[0034]
Next, the operation of this embodiment will be described.
[0035]
When the generator breaker 16 opens (load cut-off), the input value to the low value selector 45 instantaneously becomes the no-load rated speed equivalent GCV opening command value (FSRNL), and the fuel control valve 7 is suddenly closed. The GCV actual opening (GCV) is the no-load rated speed equivalent GCV opening command value (FSRNL). Thereby, the input value from the signal generator 44 to the low value selector 45 becomes the maximum value, and the signal value in the conventional governor control is adopted by the low value selector 45.
[0036]
The effects of the first reference example and the second reference example will be described with reference to FIG . In the figure, the horizontal axis shows the elapsed time after the load is cut off, the upper part shows the opening of the fuel control valve, and the lower part shows the change in speed.
[0037]
In the figure, the broken line shows the effect in the prior art, and the solid line shows the effect in the embodiment of the present invention. In the prior art, after the load is interrupted, the speed is increased, so that the fuel control valve 7 shifts to the closing operation, and after a few seconds, finally the minimum opening is reached. On the other hand, according to the present embodiment, the fuel control valve 7 instantaneously shifts to the closing operation without waiting for the speed increase. For this reason, the energy input to the gas turbine is reduced as compared with the prior art (the fuel corresponding to the shaded area in the figure is reduced). For this reason, as shown in the lower figure, the increase in speed is reduced and the peak speed is also reduced.
[0038]
3 and 4 show a second embodiment of the present invention , which will be described below.
[0039]
In FIG. 3 , reference numeral 51 denotes a pipe connecting the discharge part of the compressor 1 and the exhaust part of the turbine 3, and this pipe 51 is provided with a control valve 52, which is shown in FIG. As described above, the function is controlled by the function generator 53 having the turbine actual speed signal (TNH) as an input.
[0040]
This function generator 53 has a relationship between the turbine actual speed (TNH) and the control valve opening degree. The relationship is fully closed up to a speed of 102%, and the valve is opened by a linear function beyond that. The degree is set to be fully open at 106% or more.
[0041]
Since other configurations are the same as those of the first embodiment, the description thereof is omitted.
[0042]
Next, the operation of this embodiment will be described.
[0043]
If load interruption occurs and the speed increases, the turbine actual speed signal (TNH) detected by the speed detector 8 increases. When the speed exceeds 102%, the control valve 52 opens according to the signal of the function generator 53, Compressor discharge air flows to the turbine exhaust side. At a speed of 102% or less, the control valve 52 is fully closed.
[0044]
The effect of the present embodiment will be described with reference to FIG . In the figure, the horizontal axis shows the elapsed time after load interruption, the upper part shows the opening degree of the inlet guide vanes, and the lower part shows the change in speed. In the figure, the broken line shows the effect in the prior art, the solid line shows the effect in the first embodiment, and the alternate long and short dash line shows the effect in this embodiment.
[0045]
After the load is cut off, according to the present embodiment, the control valve 52 shifts to the opening operation as the speed increases, and the generated energy of the turbine is reduced, so that the peak value of the speed is reduced as shown in the lower figure. It is possible to quickly return to the rated speed.
[0046]
【The invention's effect】
As described above, according to the first aspect of the present invention, when a speed increase is detected by the speed detector, an opening signal of the inlet guide blade is output from the function generator by the increase function. The intake air flow rate can be increased and the compressor drive power can be increased. For this reason, the braking force of the shaft increases, and the increased speed can be reduced to the rated speed at an early stage.
[0047]
According to claim 2 of the present invention, when the load is interrupted, the control valve on the pipeline is opened, and the compressed air is extracted from the discharge part of the compressor and flows to the discharge part of the turbine. The amount of air passing through the machine increases, the braking force of the shaft increases, and the increased speed can be reduced to the rated speed earlier.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a gas turbine according to a first embodiment of the present invention.
FIG. 2 is a graph showing the effect of the apparatus of FIG. 1 in comparison with a conventional apparatus.
FIG. 3 is a configuration diagram showing a gas turbine according to a second embodiment of the present invention.
4 is a block diagram of the apparatus shown in FIG .
5 is a graph showing the effect of the apparatus of FIG . 3 in comparison with the apparatus of FIG. 1 and the conventional apparatus .
FIG. 6 is a block diagram showing a first reference example of a gas turbine .
FIG. 7 is a block diagram showing a second reference example of the gas turbine .
FIG. 8 is a graph showing the effect of the device of FIGS. 6 and 7 in comparison with a conventional device .
FIG. 9 is a configuration diagram showing equipment in a gas turbine or a combined cycle system.
FIG. 10 is a block diagram showing a conventional gas turbine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Compressor 2 Combustor 3 Turbine 4 Steam turbine 5 Generator 6 Inlet guide vane 7 Fuel control valve 8 Speed detector 9 Compressor discharge pressure detector 10 Exhaust gas temperature detector 11, 15 Subtractor 12, 14, 16, 21 , 31, 53 Function generators 13, 17 Adder 18 Intermediate value selector 22 High value selector 32 Calculator 33 Comparator 34, 43, 44, 46 Signal generator 35, 45 Low value selector 41 Generator breaker 42 Detector 47 Signal holding circuit 51 Pipe line 52 Control valve

Claims (2)

In a gas turbine having a guide vane for adjusting the amount of air sucked into the compressor and operated at a speed controlled to a rated speed, a speed detector for detecting an actual speed of the gas turbine, an actual speed in the speed detector Based on the function generator that outputs the opening signal of the inlet guide blade according to the actual speed detection value when the speed detection value exceeds the rated speed, and the opening signal of the inlet guide blade from the function generator A gas turbine comprising: a control device that drives the inlet guide vanes . Connected between the discharge part of the compressor and the exhaust part of the turbine, and a pipe line for extracting compressed air, and provided in this pipe line and opened when the load is interrupted, the compressed air is sent to the exhaust part of the turbine. The gas turbine according to claim 1, further comprising a control valve for flowing into the gas turbine .

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