JPH08165934A - Gas turbine over-speed reducing device - Google Patents

Abstract

PURPOSE: To early lower the speed of a gas turbine to the rated speed at the time of load shutdown. CONSTITUTION: A gas turbine over-speed reducing device comprises a speed detector 8 for detecting the actual speed of a turbine. The device further comprises a function generator 21 having the relationship between the turbine actual speed and the speed setting inlet guide blade opening. When a speed increase is detected by the speed detector 8, an open signal for an inlet guide blade 6 is output from the function generator 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine overspeed reducing device for reducing a rate of overspeed that occurs during a transition such as load shedding in a gas turbine system or a combined cycle system used for power generation or the like.

[0002]

2. Description of the Related Art A long-term interruption of power supply due to an accident at a power plant has a high social impact, and a situation such as a turbine runaway causes a large-scale fire and equipment damage. Even if such a situation is encountered, reliable equipment that can maintain a healthy state is required. For example, in the event of an accident on the transmission system due to a lightning strike,
The power plant is instantaneously disconnected from the power transmission system, and the power supply is momentarily cut off (load cutoff) to protect the power transmission system. Therefore, the turbine and generator are released from the load of the power transmission system that suppresses the speed and try to run out of control, but the overspeed reduction device in the power plant reduces the overspeed and keeps it at the no-load rated speed and then the power transmission system. Power must be supplied immediately after recovery.

FIG. 9 shows the configuration of equipment in a gas turbine or a combined cycle system. The gas turbine is composed of a compressor 1, a combustor 2 and a turbine 3 (the steam turbine 4 is further coupled on the same shaft in the combined cycle), and drives a generator 5.

The gas turbine is operated with the inlet guide vanes 6 controlling the intake air amount and the fuel control valve 7 controlling the fuel input amount. The speed is detected by the speed detector 8, the compressor discharge air pressure is detected by the compressor discharge pressure detector 9, and the turbine exhaust gas temperature is detected by the exhaust gas temperature detector 10.

FIG. 10 shows the contents of a conventional gas turbine overspeed reduction device. The upper part of FIG. 10 shows the governor control contents for narrowing the fuel control valve 7 to reduce the input fuel flow rate and controlling the speed to the rated speed when the speed becomes excessive.
The lower part of FIG. 10 shows the control contents of the inlet guide vanes 6.

The turbine actual speed signal (TNH) detected by the speed detector 8 is compared with the turbine rated speed signal (Nset) which is a control set value by the subtractor 11, and when the actual speed and the rated speed are different, The speed increment, which is the difference, is the signal (Δ
N). 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 to drive the fuel control valve 7.

On the other hand, for the compressor discharge pressure signal (PCD) detected by the compressor discharge pressure detector 9, the exhaust gas temperature set value (Tset) is obtained by the function generator 14, and by the exhaust gas temperature detector 10. Measured exhaust gas temperature signal (Tex) detected
Is calculated by the subtracter 15, and the temperature increment is obtained as a signal (ΔT). In the function generator 16, from the temperature increment signal (ΔT), the inlet guide vane opening increment signal (ΔIG
V) is generated, this (ΔIGV) is added to the current IGV opening (IGV) by the adder 17, and the intermediate value selector 18
Within the range from the IGV maximum set opening (IGVmax) to the IGV minimum set opening (IGVmin).
GVset), and this signal generates an inlet guide vane opening degree command signal (IGV) to drive the inlet guide vane 6. When the load is cut off, the power plant is disconnected from the power transmission system, and the speed of the gas turbine rapidly increases.
By gradually closing, the compressor discharge pressure decreases,
In addition, the exhaust gas temperature decreases. Compressor discharge pressure signal (PC
Due to the decrease of D), the exhaust gas temperature set value (Tset)
Is maintained at a high value, while the measured exhaust gas temperature (Tex) decreases, the temperature increment signal (ΔF) becomes a negative value, and the inlet guide vane opening increment signal (ΔIGV) becomes a negative value. Will be gradually closed.

[0008]

At the time of load shedding, the power plant is disconnected from the power transmission system, and the speed of the gas turbine rapidly increases. At this time, it is desired that the fuel control valve 7 be instantly narrowed down to instantaneously reduce the input energy. 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 a value corresponding to the no-load rated speed after the load is cut off, there is a problem that the speed easily increases due to the amount of fuel (energy) input during that time.

Further, in the conventional overspeed reducing device, the inlet guide vanes 6 are gradually closed when the load is cut off.
Closing the inlet guide vanes 6 means that the air flow rate in the compressor 1 is reduced, the power required for compression is reduced and the speed does not slow down easily, and the high speed state is maintained for a long time. There is a problem that In the combined cycle, when the driving machine such as the steam turbine 4 is further added, the above-mentioned problems become more remarkable, and in consideration of the recent progress of the gas turbine high temperature technology, the increase in the equipment capacity is compared. The amount of increase in drive energy is large,
Since a large amount of power is generated by a small capacity facility, it becomes impossible to reduce the speed increase at the time of load shedding with the current technology.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a gas turbine overspeed reduction device capable of reducing the speed increase value and returning to the rated speed early. To do.

[0011]

In order to solve the above-mentioned problems, a gas turbine overspeed reduction device according to the present invention is
As described in claim 1, there is a speed detector for detecting the actual turbine speed, and the relationship between the actual turbine speed and the speed setting inlet guide vane opening, and when the speed increases, the inlet guide vane of the turbine And a function generator that outputs an open signal.

Further, the gas turbine overspeed reduction device according to the present invention, as described in claim 2, uses the standard fuel control from the relationship between the output of the generator driven by the gas turbine and the standard fuel control valve opening degree. A function generator that outputs a valve opening signal,
An arithmetic unit for obtaining the difference between the standard fuel control valve opening signal and the actual fuel control valve opening, and when the difference deviates from a certain range, the fuel control valve is rapidly narrowed down and the fuel flow rate to the combustor is unloaded. And a signal generator that reduces the flow rate to the rated speed.

Further, in the gas turbine overspeed reduction device according to the present invention, as described in claim 3, a detector for detecting whether or not the breaker of the generator driven by the gas turbine is opened, and the breaker. And a signal generator that rapidly narrows the fuel control valve when the device opens and reduces the fuel flow rate to the combustor to a flow rate equivalent to the no-load rated speed.

Still further, the gas turbine overspeed reduction device according to the present invention is, as described in claim 4, a pipe connected between the discharge part of the compressor and the exhaust part of the turbine for extracting compressed air. And a control valve which is provided in the conduit and opens when the load is cut off to allow the compressed air to flow to the exhaust portion of the turbine.

[0015]

In the gas turbine overspeed reduction device according to the present invention, when the speed detector detects an increase in speed, the function generator outputs an open signal of the inlet guide vane by the rising function, and suction air is sucked in. The amount increases and the compressor drive power increases. Therefore, the braking force of the shaft is increased, and the above speed can be reduced to the rated speed early.

In the gas turbine overspeed reduction device according to the second aspect of the invention, the difference between the standard fuel control valve opening signal from the function generator and the actual fuel control valve opening is calculated by the calculator. When the difference deviates from a certain range, it is determined that the load is cut off, and the fuel control valve is rapidly narrowed down. Therefore, the fuel flow rate, which is the input energy, can be instantly reduced to the no-load rated speed, and the speed increase after the load is cut off can be reduced.

Further, in the gas turbine overspeed reduction device according to the third aspect, the detector detects whether or not the generator breaker is open, and when it is open, it is determined that the load is cut off. However, the fuel control valve is rapidly narrowed down. Therefore, the fuel flow rate, which is the input energy, can be instantly reduced to the no-load rated speed, and the speed increase after the load is cut off can be reduced.

Furthermore, in the gas turbine overspeed reduction device according to the fourth aspect, when the load is cut off, the control valve on the pipe line is opened, and compressed air is extracted from the discharge part of the compressor to remove the turbine. It is flushed to the discharge part. Therefore, the amount of air passing through the compressor increases, the braking force of the shaft increases, and the increased speed can be reduced to the rated speed earlier.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. In addition, in order to avoid duplication of the present invention, the same parts as those of the prior art are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows a gas turbine overspeed reduction device according to a first embodiment of the present invention. In the figure, reference numeral 8 is a speed detector, and a turbine actual speed signal from this speed detector 8 is shown. (TNH) is the actual turbine speed and speed setting (IG
V) is input to a function generator 21 having a relationship with V, and from this function generator 21, the inlet guide vane set value signal (IGVn
: Speed setting IGV) is output.
The inlet guide vane set value signal (IGVn) is input to the high value selector 22 together with the inlet guide vane set value signal from the intermediate value selector 18 of the conventional inlet guide vane control device. The opening of the inlet guide vane 6 is controlled by the IGV set opening (IGVset) output from the high value selector 22.

The relationship between the actual turbine speed (TNH) and the speed setting IGV (IGVn) in the function generator 21 is, for example, a minimum value (minimum inlet guide vane opening) up to a speed of 102%, and a primary value above that. Increase the set value with a function and reach the maximum value (maximum inlet guide vane opening) at 106% or more.
Is set to be

Next, the operation of this embodiment will be described.

When the load is cut off and the speed increases, the turbine actual speed signal (TNH) detected by the speed detector 8 increases, and the speed setting IGV output from the function generator 21.
The signal value increases and reaches a maximum when the speed exceeds 106%.

On the other hand, since the signal value output from the intermediate value selector 18 of the conventional inlet guide vane control device decreases,
In the high price selector 22, the speed setting I from the function generator 21
The GV signal value is selected, the inlet guide vanes are fully opened, the braking force of the shaft is maximized, and the speed increase amount is reduced.

When 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 vanes 6 are closed.
At a speed of 2% or less, the speed setting IGV signal becomes the lowest, and the original no-load rated speed equivalent opening is restored.

The effects of this embodiment will be described with reference to FIG.
In the figure, the horizontal axis shows the elapsed time after load shedding, the upper part shows the opening of the inlet guide vane, and the lower part shows the change in speed.

In the figure, the broken line shows an example of the phenomenon in the prior art, and the solid line shows the effect of the embodiment of the present invention. In the prior art, after the load is cut off, the exhaust gas temperature decreases and the difference from the set value increases, so that the opening of the inlet guide vane shifts to the closing operation, and after several seconds, the opening finally becomes the minimum opening. On the other hand, according to the present invention, as the speed increases, the opening of the inlet guide vane shifts to the opening operation, and when the opening is 106% or more, the valve is fully opened. As a result, the peak speed value is reduced as shown in the figure below,
It is also possible to return to the rated speed faster.

FIG. 3 shows a second embodiment of the present invention, which will be described below.

In FIG. 3, reference numeral 5 is a generator, and the generator output (Load) from this generator 5 is a function generation having a relationship between the generator output (Load) and the standard GCV opening (GCVs). It is adapted to be input to the container 31. The standard GCV opening signal (GC
Vs) is input to the computing unit 32 and the actual GCV opening (GC
V) and the difference (ΔGCV) is obtained, and this difference (ΔGV
CV) is compared with the GCV opening deviation allowable amount (K) in the comparator 33. The output signal a from the comparator 33 is input to the signal generator 34.

The signal generator 34 also receives the maximum value (100%) of the signal b and the no-load rated speed equivalent GCV.
The opening command value (FSRNL) is input, and the signal generator 34 calculates the difference (ΔGCV) to be G
Outputs the no-load rated speed equivalent GCV opening command value (FSRNL) when the deviation exceeds the CV opening deviation allowable amount (K), and outputs the maximum value (100%) when the deviation does not occur. The signal d is output. The 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 GCV opening command (FSR) output from the low value selector 35.
The fuel control valve 7 is controlled in opening degree.

The relationship between the generator output (Load) and the standard GCV opening (GCVs) in the function generator 31 is set as, for example, a linear function that rises to the right.

Next, the operation of this embodiment will be described.

If load shedding occurs, 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 actual GCV opening (GCV) is a large value before load shedding,
Since the opening deviation allowable amount (K) is exceeded, the input value to the low value selector 35 instantly becomes the no-load rated speed equivalent GCV opening command value (FSRNL), and the fuel control valve 7 starts the rapid closing operation. However, the actual GCV opening (GCV) becomes the minimum value (FSRNL) in the function generator 31. As a result, the GCV opening deviation amount (ΔGCV) becomes less than or equal to 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 is operated by the conventional governor control. The signal value of is adopted.

FIG. 4 shows a third embodiment of the present invention, which will be described below.

In FIG. 4, reference numeral 41 is a generator breaker, and the opening and closing operations of the generator breaker 41 are performed by the detector 4.
2 detected, generator breaker 41 open operation (load cutoff)
If so, the detector 42 outputs the signal e. Then, this signal e is the signal generator 43.
The signal generator 43 outputs a signal a that is turned on for one shot when the signal e is input.

This signal a is the maximum value (100%) of the signal b and the no-load rated speed equivalent GCV opening command value (FSR).
NL) signal c together with the signal a from the signal generator 44.
Is off when it is off, and when it is on, it is equivalent to the unloaded rated speed equivalent GCV opening command value (FSR).
NL) is output as the output signal d.
Then, this 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 by the GCV opening command (FSR) output from the low value selector 45. The opening is controlled.

The signal c of the GCV opening command value (FSRNL) corresponding to the no-load rated speed is input to the signal generator 46 together with the actual GCV opening (GCV), and from this signal generator 46. Output signal f of the signal holding circuit 4
It is designed to be input to 7. And this
When the signal generator 44 generates the GCV opening command value (FSRNL) corresponding to the no-load rated speed, the actual GCV opening (GSR)
The signal is held until CV) becomes the same as the signal c.

Next, the operation of this embodiment will be described.

When the generator breaker 16 opens (load is cut off), the input value to the low value selector 45 instantly becomes the no-load rated speed equivalent GCV opening command value (FSRNL), and the fuel control valve 7 is suddenly opened. The closing operation is started, and the actual GCV opening (GCV) becomes the no-load rated speed equivalent GCV opening command value (FSRNL). As a result, the input value from the signal generator 44 to the low value selector 45 becomes the maximum value, and the low value selector 45 adopts the signal value in the conventional governor control.

The effects of the second and third embodiments 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.

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 cut off, the speed increases and the fuel control valve 7 shifts to the closing operation, and after several seconds, the fuel control valve 7 finally reaches the minimum opening degree. On the other hand, according to the present embodiment, the fuel control valve 7 instantly shifts to the closing operation without waiting for the speed increase. Therefore, the energy input to the gas turbine is reduced (the fuel corresponding to the shaded area in the figure is reduced) compared to the conventional technique. As a result, the increase in speed is reduced and the peak speed is reduced as shown in the lower diagram.

6 and 7 show a fourth embodiment of the present invention, which will be described below.

In FIG. 6, reference numeral 51 is a conduit connecting the discharge part of the compressor 1 and the exhaust part of the turbine 3, and a control valve 52 is provided in this conduit 51. As shown in FIG. 7, it is controlled by the function generator 53 which receives the turbine actual speed signal (TNH).

The function generator 53 has a relationship between the turbine actual speed (TNH) and the control valve opening. The relationship is that the speed is up to 102%, it is fully closed, and above that, it becomes a linear function. The valve opening is increased so that the valve is fully opened at 106% or more.

Regarding other constitutions, the first
Since the configuration is the same as that of the embodiment, its description is omitted.

Next, the operation of this embodiment will be described.

When the load is cut off and the speed increases, the actual turbine speed signal (TNH) detected by the speed detector 8 is detected.
Is increased and exceeds 102% speed, the control valve 52 opens according to the signal of the function generator 53, and the compressor discharge air flows to the turbine exhaust side. When the speed is 102% or less, the control valve 5
2 is fully closed.

The effect of this embodiment will be described with reference to FIG. In the figure, the horizontal axis represents the elapsed time after load shedding, the upper part represents the opening of the inlet guide vane, and the lower part represents 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 the present embodiment.

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 energy generated by the turbine is reduced, so that the peak speed value is reduced as shown in the lower diagram. It is also possible to return to the rated speed faster.

[0050]

As described above, according to claim 1 of the present invention, when a speed increase is detected by the speed detector, the function generator outputs an open signal of the inlet guide vane by the increase function. Therefore, the intake air flow rate is increased and the compressor driving power can be increased. For this reason,
The braking force of the shaft is increased, and the increased speed can be reduced to the rated speed early.

According to the second aspect of the present invention, a difference between the standard fuel control valve opening signal from the function generator and the actual fuel control valve opening is obtained, and when the difference deviates from a certain range, Since it is determined that the load has been cut off and the fuel control valve is being rapidly narrowed down, the fuel flow rate, which is the input energy, is instantly reduced to the no-load rated speed, and the speed increase after the load is cut off is reduced. You can

According to claim 3 of the present invention, the opening of the breaker of the generator is detected to determine that the load has been cut off, and the fuel control valve is rapidly narrowed down. The flow rate can be instantly reduced to a value corresponding to the no-load rated speed, and the speed increase after the load is cut off can be reduced.

According to the fourth aspect of the present invention, when the load is cut off, the control valve on the pipeline is opened, and the compressed air is extracted from the discharge part of the compressor and is made to flow to the discharge part of the turbine. Therefore, 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.

[Brief description of drawings]

FIG. 1 is a block diagram showing a gas turbine overspeed reduction device according to a first embodiment of the present invention.

FIG. 2 is a graph showing the effect of the device of FIG. 1 in comparison with a conventional device.

FIG. 3 is a block diagram showing a gas turbine overspeed reduction device according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a gas turbine overspeed reduction device according to a third embodiment of the present invention.

FIG. 5 is a graph showing the effect of the device of FIGS. 3 and 4 in comparison with a conventional device.

FIG. 6 is a configuration diagram showing a gas turbine overspeed reduction device according to a fourth embodiment of the present invention.

FIG. 7 is a block diagram of the apparatus shown in FIG.

8 is a graph showing the effect of the apparatus of FIG. 6 in comparison with the apparatus of FIG. 1 and a conventional apparatus.

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 overspeed reduction device.

[Explanation 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 generator 13,17 Adder 18 Intermediate value selector 22 High value selector 32 Operator 33 Comparator 34,43,44,46 Signal generator 35,45 Low value selector 41 Generator breaker 42 Detector 47 Signal holding circuit 51 Pipeline 52 Control valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F02C 9/46

Claims (4)

[Claims] 1. A speed detector for detecting an actual turbine speed, and a relationship between the actual turbine speed and a speed setting inlet guide vane opening. When the speed increases, an open signal of an inlet guide vane of the turbine is output. A gas turbine overspeed reduction device, comprising: 2. A function generator that outputs a standard fuel control valve opening signal from the relationship between the output of a generator driven by a gas turbine and the standard fuel control valve opening, and a standard fuel control valve opening signal and an actual signal generator. A calculator for obtaining the difference from the fuel control valve opening, and a signal generation for rapidly narrowing the fuel control valve when the difference deviates from a certain range to reduce the fuel flow rate to the combustor to a flow rate equivalent to the no-load rated speed. And a gas turbine overspeed reduction device. 3. A detector for detecting whether or not a circuit breaker of a generator driven by a gas turbine is opened, and a fuel control valve is rapidly narrowed down when the circuit breaker is opened so that a fuel flow rate to a combustor is reduced. A gas turbine overspeed reduction device, comprising: a signal generator that reduces the flow rate to a loadless rated speed. 4. A pipe line that is connected between a discharge part of a compressor and an exhaust part of a turbine and extracts compressed air, and a pipe line that is provided in this pipe line and opens when a load is cut off. 2. A gas turbine overspeed reduction device according to claim 1, further comprising a control valve for flowing the gas to an exhaust portion of the turbine.