JP2000116196A - Gas turbine generator and operation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the output of a gas turbine generator roughly constant even if atmospheric temperature changes, by using a variable-speed generator as a generator driven by a gas turbine, and AC-energizing the secondary winding of the variable-speed generator. SOLUTION: This variable-speed gas turbine generator is provided with a compressor which introduces and compresses air, a combustor which burns the air and fuel compressed by a compressor, a gas turbine driven by the combustion gas from the combustor, and a generator 5 whose primary winding 15 is connected to a power system and whose secondary winding 16 is AC- energized. The generator 5 having the primary winding 15 and the secondary winding 16 energized using three-phase alternating current is formed so as to keep the frequency of AC energizing current variable even if a rotor is in a mechanically stationary condition. Thus, it is possible to keep the frequency outputted from the generator 5 roughly constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine power generator and a method of operating the same, and more particularly, to a gas turbine power generator in which the rotational speed of a shaft connecting a gas turbine and a generator is arbitrarily changed. The present invention relates to an operable variable speed gas turbine power generator and an operation method thereof.

[0002]

2. Description of the Related Art A gas turbine power generator includes a compressor for sucking and compressing air existing as air, a combustor for burning using air and fuel compressed by the compressor, and a combustor produced by the combustor. A gas turbine driven by combustion air and a generator are provided. Then, the compressor and the generator are driven by the gas turbine connected by one shaft.

In such a gas turbine power generator, the generator is operated while being connected to a power system. For this reason, a synchronous machine is usually adopted as the generator. Therefore, the rotation speed of the shaft of the generator in the gas turbine power generator is proportional to the system frequency. That is, the number of rotations of the generator shaft changes (for example, from 3000 rpm to 3100 rp).
m), the system frequency also changes (for example, 50 Hz to 52 H
z).

[0004]

The gas turbine power generation apparatus uses air compressed by taking in air by a compressor. Therefore, there is a problem that when the temperature of the intake air changes, the power generation output of the gas turbine power generator changes. That is, there is a characteristic that the higher the temperature of the air (atmosphere) to be taken, the lower the power generation output.
For example, a gas turbine generator capable of producing a rated output at an atmospheric temperature of 4 ° C. has a rated output of 90% or less at an atmospheric temperature of 40 ° C. The reason for this is that the amount of air taken in by the compressor, the so-called intake air amount (weight flow rate), decreases as the temperature of the air increases.

In view of the above, it is an object of the present invention to provide a variable-speed gas turbine generator capable of keeping the output of the gas turbine generator substantially constant even when the atmospheric temperature changes, and an operation method thereof. And

Further, the present invention provides a variable speed gas turbine power generator and a method of operating the same, which can keep the system frequency of the generator substantially constant even when the rotation speed of the compressor shaft changes for some reason. The purpose is to do.

[0007]

According to the present invention, a generator driven by a gas turbine is a variable speed generator, and a secondary winding of the generator is AC-excited. As a result, while maintaining the frequency output from the primary winding as the system frequency,
The rotation speed of the secondary winding can be changed. And
The rotation speed of the secondary winding is changed according to the atmospheric temperature. still,
In the present invention, it is preferable that the primary winding is a stator and the secondary winding is a rotor.

[0008] The variable speed gas turbine power generator according to the present invention comprises:
A compressor that takes in air and compresses it, a combustor that burns the air and fuel compressed by the compressor, a gas turbine that is driven by combustion gas from the combustor, and a secondary winding whose primary winding is connected to the power system And a generator wherein the wires are AC-excited.

In a normal gas turbine power generator, when the air supplied from the compressor is constant, that is, when the shaft of the compressor is rotating at a constant rotation speed, the volume flow rate of the atmosphere increases as the atmospheric temperature rises. On the other hand, the weight flow rate decreases, and the electric output of the gas turbine generator decreases. The combustor burns with a substantially constant fuel-air ratio. That is, the combustor burns by reducing the fuel by an amount corresponding to the decrease in the weight flow rate of the air, so that the electric output is reduced. To prevent this decrease in electric output, if the rotational speed of the compressor shaft is increased so as to increase the amount of supplied air, the rotational speed of the generator shaft that operates in conjunction with this compressor also increases, Cannot be maintained at a constant frequency. The present invention can solve such a problem, and prevents a decrease in electric output even when the number of rotations of the shaft of the compressor deteriorates, and keeps the system frequency substantially constant.

[0010] The present invention uses a generator having a primary winding (stator) and a secondary winding (rotor) that are excited using three-phase alternating current, thereby reducing the (mechanical) of the generator shaft. ) Even if the rotation speed changes, the (electrical) frequency output from the generator can be made substantially constant. This generator, for example,
Even if the rotor is mechanically stationary, the frequency of the AC exciting current (the number of rotations of the stator-side magnetic field) can be made variable, thereby achieving the effects of the present invention.

The system (predetermined) frequency may be changed by, for example, changing the atmospheric temperature or changing the output load of the plant based on a load request signal. Disturbance (load rejection due to lightning, etc.) is also conceivable.

For example, an operation state of the gas turbine power generator when the load shedding is prevented by a lightning strike or the like will be described.

In a gas turbine power generator in which a gas turbine and a generator motor (generator) are connected coaxially,
The following relational expression holds.

[0014]

(Equation 1)

Here, I _w is the inertia effect of the generator, T _IW
Is the torque (energy) generated on the gas turbine side, T _OW
Indicates the torque (energy) generated on the generator side.

On the other hand, the following relational expression holds for the behavior on the power system side where the system frequency rises and falls.

[0017]

(Equation 2)

[0018] In this case, I _S is inertia effect T _OS of the electric power system side
The total torque (energy) T _IS output and consumed from the entire power system indicates the total torque (energy) input to the entire power system. T _OW shown in equation (1) is T _IS
Is an element of

In such an operating state, when a load rejection such as a lightning strike occurs, T _OS rapidly decreases and w _S increases. This means that the system frequency increases. In the present invention,
An AC excitation device such as a cycloconverter is operated to electrically reduce T _OW and control so as to reduce electric output, thereby suppressing an increase in w (mechanical shaft rotation speed). That is, by adjusting the magnitude and phase of the AC exciting current of the AC exciting device, the input and power factor on the electric side can be reduced regardless of the operation on the gas turbine side, such as reducing the amount of fuel supplied to the combustor. Can control. As a result, fast responsive control becomes possible. The present invention addresses changes due to these various factors.

Then, the gas turbine and the generator are connected by the same shaft. The same shaft means one shaft, and the shaft of the gas turbine and the shaft of the generator may be coupled.

Further, the variable speed gas turbine power generator includes a fuel control device that determines and controls the amount of fuel supplied to the combustor according to a load request signal, and the power generation device according to the load request signal and the atmospheric temperature. And an excitation control device for adjusting the amount of AC excitation of the machine.

Adjusting the amount of AC excitation according to the atmospheric temperature means that the atmospheric temperature is continuously measured and the amount of AC excitation is controlled with reference to a table showing the relationship between the temperature and the amount of AC excitation. I do. In addition, a predetermined temperature range, for example, 20 to
If the temperature changes between 25 ° C., this means setting and controlling the AC excitation amount (shaft rotation speed) at the upper limit (25 ° C.) within the temperature range. It is preferable that the table is created at a predetermined temperature interval, for example, at an interval of 0.5 to 1.0 ° C.

Further, the secondary winding of the generator is desirably connected to an AC excitation device that excites the winding with AC.

Further, according to the present invention, it is possible to adjust the amount of AC excitation of the generator in accordance with the amount of fuel and the atmospheric temperature determined by the fuel control device.

Further, it is preferable to adjust the amount of AC excitation of the generator based on the atmospheric temperature and to control the rotational speed of the shaft.

On the other hand, in the operation method of the variable speed gas turbine power generator according to the present invention, the compressor takes in the air, compresses the air, burns the compressed air and fuel in a combustor, and uses the burned gas. It drives a gas turbine and drives a generator coupled to the gas turbine by a single shaft.

The excitation frequency for the generator is made variable in accordance with the temperature of the atmosphere.

Further, when making a substantially constant operation plan for the output of the generator irrespective of fluctuations in the atmospheric temperature, when the temperature of the air rises (falls), the rotational speed of the shaft may be increased (decreased). preferable.

Further, it is preferable that the amount of AC excitation of the secondary winding be set smaller when the temperature of the atmosphere is lower than when the temperature of the atmosphere is higher. Then, the rotation speed of the magnetic field of the generator is
It is also possible to make it variable according to the fluctuation of the output of the gas turbine, and when the temperature of the atmosphere rises, it is also possible to control the excitation frequency for the generator so that the output frequency of the generator is almost constant. It is possible.

Some power generators generate steam using the exhaust heat of the exhaust gas from the gas turbine to drive the steam turbine. By driving the steam turbine, a generator is driven to generate power. By configuring a combined cycle plant in which the gas turbine power generation device of the present invention and such a steam turbine power generation device are combined, the load can be changed more rapidly and the power generation efficiency can be increased.

Further, in the combined cycle plant of the present invention, the gas turbine driven by the combustion gas, the primary winding connected to the gas turbine by one shaft is connected to the electric power system, and the secondary winding is AC-excited. It has a generator, a boiler (exhaust heat recovery boiler) for exchanging heat with exhaust gas from a gas turbine, and a steam turbine driven by steam generated from the boiler. Then, a load request signal required from the central power supply command center or the like to the power plant where this plant is installed and the temperature of the air used to generate the combustion gas (atmospheric temperature)
Based on the above, the amount of AC excitation of the generator is adjusted.

According to the present invention, the temperature of the air taken into the compressor is used as one parameter to control the rotation speed of the secondary winding of the generator. Then, the frequency output from the primary winding (system frequency) is maintained.

Therefore, by changing the rotation speed of the secondary winding in accordance with the temperature of the atmosphere, even if the temperature of the air (atmosphere) taken into the compressor changes, the intake air amount (weight flow rate) of the air is changed. It can be kept as constant as possible.

As a result, it is possible to suppress a change in the output of the generator due to a change in the temperature of the atmosphere, and to keep the output as constant as possible.

The gas turbine is usually operated by controlling the ratio of air and fuel (air-fuel ratio) introduced into the combustor to be substantially constant. Under such an operation, when the required load fluctuates, the amount of fuel and the amount of air introduced into the combustor change. In the present invention, the amount of air taken into the compressor is changed by controlling the mechanical rotation speed of the shaft. At this time, the amount of AC excitation applied to the secondary winding of the generator is controlled in order to operate without changing the system frequency.

In other words, the present invention is intended to provide a desired output according to demand, which has almost no relation to a change in the temperature of the atmosphere. For example, when the temperature of the atmosphere increases, the volume of the air is increased. The flow rate increases and the weight flow rate decreases. Therefore, it is necessary to increase the rotation speed of the compressor to increase the amount of air. Following this, the fuel amount also increases. This is to keep the fuel-air ratio constant. As a result, the frequency output from the generator, which changes in conjunction with the rotation speed of the shaft of the compressor, increases. This imparts a slip frequency to the secondary winding of the generator, reducing its apparent frequency.

Even when the required load changes, it is necessary to control the air and the fuel, and the same operation is used.

[0038]

FIG. 1 shows an embodiment of a variable speed gas turbine power generator according to the present invention.

The gas turbine power generator includes a compressor 1 that draws in air and compresses the air, and a combustor 2 that burns using compressed air and fuel generated by the compressor 1.
And a gas turbine 3 driven by combustion air generated by the combustor 2 and a variable speed generator 5.

The compressor 1 and the variable speed generator 5 are driven by the gas turbine 3 connected by one shaft. Reference numeral 4 denotes a fuel supply device for supplying fuel to the combustor 2, reference numeral 18 denotes an electric power system, and reference numeral 9 denotes an AC exciting device for exciting the generator 5 with AC.

The arithmetic unit 8 uses, as input signals, a load request signal Pd from a central power supply command center and the like and an atmospheric temperature T detected by an atmospheric temperature detector to operate the variable speed gas turbine power generator. Then, the target value Fd of the fuel amount and the target value Ed of the AC excitation amount of the secondary winding of the generator 5 (this generator is a variable speed generator capable of changing the rotation speed) are determined. .

The fuel control device 6 controls the opening of the fuel supply device 4 using the target value Fd of the fuel amount as an input signal so that the fuel amount supplied to the combustor 2 becomes a predetermined value.

Further, the excitation control device 7 uses the target value Ed of the AC excitation amount as an input signal, and controls the AC excitation device 9 to set the AC excitation amount of the generator 5, for example, its phase and magnitude to predetermined values. Control. The AC excitation device 9 is a device for converting a frequency, and performs three-phase AC excitation. As the AC excitation device 9, a converter using a cycloconverter or a GTO element can be used.

Next, a schematic configuration of the variable speed generator used in the present invention will be described with reference to FIG. Generator (variable speed generator) 5 capable of changing this rotation speed
Has basically the same configuration as a generator used in a variable speed pumped storage power generator that assembles water upward and generates power using nighttime power.

In FIG. 2, the variable speed generator 5 includes a primary winding 15 connected to a power system 18 and a secondary winding 16 coupled to a shaft of a gas turbine and rotating. The secondary winding 16 is excited at a variable frequency by the AC exciting device 9. Reference numeral 6 denotes a fuel control device.

The AC excitation device 9 has one end connected to the power system 18.
And so on. The AC obtained from this power supply is
It is converted into a three-phase alternating current having an appropriate magnitude and phase, and is output as a variable frequency or a variable voltage. With this output, the secondary winding 16 is subjected to three-phase AC excitation.

In the variable speed generator 5, the frequency of the primary winding 15 is the frequency fo of the power system 18, the frequency proportional to the rotation speed of the generator shaft is fm, and the excitation frequency 17 of the secondary winding 16 is fe, between these, fo = f
The relationship of m + fe is established. Where the frequency f of the primary winding
o is the rotation speed of the stator side magnetic field, and the frequency fm is the mechanical rotation speed of the rotor. Further, the excitation frequency fe is a speed at which the magnetic field moves on the rotor by the AC excitation, and is positive when it is in the same direction with respect to fm (when the rotation speed of the shaft is low, when it is lower than the reference atmospheric temperature). Fm
In the opposite direction (when the rotation speed of the shaft is high, when the temperature is equal to or higher than the reference atmospheric temperature), a negative value is shown. Furthermore, by changing the phase of the exciting current (the amount of AC excitation) by 180 °, the direction can be reversed.

Normally, fo is constant, and fm changes as a result of controlling by changing fe. This means that by changing the excitation frequency fe of the secondary winding 16, the mechanical rotation speed of the gas turbine 3 can be changed, which means that the intake air amount of the compressor 1 can be controlled.

That is, for example, when it is necessary to increase the mechanical rotation speed of the shaft of the compressor due to an increase in the atmospheric temperature, normally, in conjunction with the increase in the rotation speed of this shaft,
The number of revolutions of the generator shaft also increases. As a result, the system frequency also increases, but this increase in the system frequency is not preferable from the viewpoint of stability of power quality. Therefore, the excitation frequency (fe) is controlled so that the system frequency (fo) becomes constant even when the shaft rotation speed (fm) increases. In this way, by exciting the AC at a frequency corresponding to the speed at which the magnetic field on the rotor moves on the rotor, the speeds of the magnetic fields on the stator and the rotor are matched, synchronized with the system, and stable. Driving can be performed.

The present invention has been made using such a principle.

According to the present invention, even when the temperature of the atmosphere changes,
This realizes constant control of the output from the generator.

The arithmetic unit 8 shown in FIG. 2 controls the output from the generator to a constant value so that the target value Fd of the fuel amount and the target value Ed of the AC excitation amount of the secondary winding 16 of the variable speed generator are controlled. To determine.

Here, the relationship between the output of the gas turbine and the atmospheric temperature will be described with reference to FIG. In FIG. 3, the horizontal axis indicates the atmospheric temperature, and the vertical axis indicates the output of the gas turbine. The output 118 of the gas turbine changes depending on the ambient temperature, and the higher the ambient temperature, the lower the output of the gas turbine.
The gas turbine is usually operated at a constant rotation speed, and the volume flow rate of the air (intake air) sucked into the compressor is constant. However, what is related to the output of the gas turbine is the weight flow rate of the intake air. Weight flow is determined by multiplying volume flow by density, which is a function of temperature. That is, in a high temperature state, the density of the air decreases, and as a result, the weight flow rate decreases, and the output of the gas turbine also decreases.

Because of such a relationship, the output of the gas turbine (nominal approval output) that is publicly indicated is usually defined by the output at a specific temperature near normal temperature (in the case shown in FIG. 4 degrees Celsius). Therefore, normal gas turbines failed to produce nominally permitted power in summer. On the other hand, in the present invention, the gas turbine is operated while changing the rotation speed,
As shown by the characteristic 120, the operation is performed by changing the rotation speed according to the atmospheric temperature so that the higher the atmospheric temperature (lower temperature), the higher the rotational speed of the gas turbine (lower). At this time, the weight flow rate of the air can be kept constant, and the output of the gas turbine can be kept constant irrespective of the change in the atmospheric temperature, as indicated by a characteristic 119. in this way,
It is good practice to operate the gas turbine by changing the rotation speed (variable speed operation). However, a synchronous generator operated by being connected to an electric power system cannot operate by changing the rotation speed (variable speed operation) or by changing the frequency (variable frequency operation). Is adopted to keep the frequency constant.

In order to realize the characteristic 119 shown in FIG. 3 and to make the output of the gas turbine almost constant irrespective of changes in the atmospheric temperature, the arithmetic unit 8 shown in FIG. 81 and 82 are provided.

Among them, the target value F of the fuel amount (fuel flow rate)
The function generator 82 that determines d takes the load request signal Pd as an input signal. Since the load request signal and the target value of the fuel amount have a substantially proportional relationship, the target value Fd of the fuel amount is obtained. In addition, the target value Fd of the fuel amount can be adopted without substantially changing the calculation method in the conventional fuel amount control device.

The target value Ed of the amount of AC excitation of the secondary winding 16 of the variable speed generator is determined using the load request signal Pd and the atmospheric temperature T as input signals. The target value Ed of the amount of AC excitation is
For example, the rotation speed realized by the variable-speed generator 5.

For example, when the atmospheric temperature is 4 degrees Celsius,
As in the case of the characteristic b, when the load request signal Pd = 0, the rotation speed is equivalent to the rated frequency of 50 (Hz). As the load request signal Pd increases / decreases, a command to increase / decrease the rotation speed is given.

When the atmospheric temperature is high, the characteristic b is moved upward like the characteristic a, and the rotation speed (the number of rotations) is increased.
Command to set.

When the atmospheric temperature is low, the characteristic b is moved downward as indicated by the characteristic c, and the rotation speed (the number of rotations)
Command to set.

The excitation control device 7 sets a target value E of the AC excitation amount.
d (target value of rotation speed) is used as an input signal. In order to realize this target value, the slip frequency of the variable speed generator 5 is controlled. For example, in the above equation, the frequency fo of the power system
Is set to 50 (Hz) of the rated (system) frequency. The target value Ed of the rotation speed is a frequency fm corresponding to the rotation speed of the shaft of the variable speed generator 5. This is 55 (H
z), the excitation frequency (slip frequency) fe of the secondary winding is set to minus 5 (Hz).
Controls the amount of AC excitation in the secondary winding. Here, minus means that the direction of the magnetic flux is opposite.

The amount of three-phase AC excitation of the secondary winding 16 is
It is determined by the AC excitation device 9. When adjusting the active power as the load request signal Pd, the phase angle of the three-phase AC excitation amount may be adjusted, and when adjusting the reactive power as the load request command Pd, the magnitude of the three-phase AC excitation amount may be adjusted. good.

By performing the above control, the gas turbine is charged with a fuel amount in accordance with a predetermined load request signal Pd and performs combustion. Furthermore, by rotating the shaft of the compressor connected to the shaft of the generator at a rotation speed in consideration of the change in the atmospheric temperature, it is possible to take in the air at a weight flow rate in accordance with the load request command Pd.

As a result, a desired electric output can be obtained, and a constant frequency can be realized as a generator.

FIG. 4 shows another embodiment of the present invention. In this embodiment, the configuration of the function generator 83 shown in the arithmetic unit 8 is different from that of FIG. Function generator 8
2 obtains a target value Fd of the fuel amount from the load request command Pd. Further, the function generator 83 uses the target value Fd of the fuel amount and the atmospheric temperature T as parameters to set the target value E of the AC excitation amount.
Find d. It should be noted that the method of creating the target value signal can be appropriately selected and adopted. The other symbols shown in FIG. 4 have the same meanings as the symbols shown in FIG. The reason will be described with reference to FIGS. FIG. 5 shows the air flow rate (weight flow rate) of the compressor on the horizontal axis and the pressure ratio between the inlet and the outlet of the compressor on the vertical axis. FIG.
The horizontal axis shows the load, the left vertical axis shows the air flow rate (weight flow rate), and the right vertical axis shows the gas turbine inlet temperature.

In FIG. 5, the internal efficiency 22 of the compressor, which is one index indicating the performance of the compressor, is indicated by an elliptical contour line centered on the rated operating point P. That is, the internal efficiency decreases to 0.85, 0.8, 0.75 toward the outside of the point P. A line connecting the direction in which the change in the efficiency is the smallest with respect to the change in the state of the compressor is referred to as an operation line 24. On this operation line 24, the efficiency of the compressor is the highest and the compressor operates stably.

In the operation (partial load) in which the flow rate of the air supplied from the compressor is reduced based on the conventional method, the rotation speed of the shaft of the compressor is kept constant. Is performed. That is, the operating point of the compressor due to the decrease in the air flow rate (W ₁ → W ₂ ) is determined by moving upward (point P → point Q) on the constant speed line 21 where the mechanical rotation speed of the shaft is constant. Become. In this direction, the gradient in which the internal efficiency 22 of the compressor decreases is the largest.

At this time, the operating point of the compressor is
It is close to the surge line 23 which gives the limit of the compressor stability as the load is reduced. The air flow rate sucked by the compressor cannot be reduced below the air flow rate W ₂ (air flow rate shown in FIG. 6) at the point Q where the constant speed line 21 and the surge line 23 intersect. On the other hand, the amount of air flow necessary and sufficient for combustion decreases as the load decreases. Therefore, at a load lower than the point Q, only a part of the air sucked by the compressor contributes to the combustion. The remaining air will be mixed with the combustion gases without being heated.

As a result, the temperature of the combustion gas at the inlet of the gas turbine decreases, and the thermal efficiency of the gas turbine decreases. Since the proportion of air that contributes to combustion decreases as the load decreases, the thermal efficiency of the gas turbine decreases rapidly as the load decreases. In other words, reducing the air flow rate while keeping the rotation speed of the shaft constant causes a drastic decrease in internal efficiency and reduces the air flow rate only to the limit of the occurrence of the surging phenomenon of the compressor.

In the present embodiment, since the shaft can be operated with the mechanical rotation speed being variable, even when the air flow rate is reduced (W ₁ → W ₂ ), the operation is performed along the operation line 24 (W ₁ → W ₂ ). Point P → Point R) Operation is possible. This operation line 2
By operating according to 4, the internal air flow can be reduced to the desired air flow without a sudden decrease in internal efficiency or without approaching the surge line 23.

FIG. 6 is a characteristic diagram clearly showing the above relationship. As shown by characteristics 25 and 35 (solid lines) in FIG. 6, the temperature of the combustion gas at the inlet of the gas turbine increases as the load increases, and is substantially constant at about 1300 ° C. when the load is about 75 to 80% or more. (Solid line 35). Also,
Air flow rate, the load is substantially constant at W ₂ of about when: about 75% to 80%, the load rises to W about ₁ when not less than about 75% to 80% (solid line 25). On the contrary,
As shown by the characteristics 26 and 36 (dotted lines) in FIG. 6, by using the present invention, the temperature of the combustion gas at the inlet of the gas turbine can be kept substantially constant at about 1300 ° C. even when the load changes. Yes (dotted line 36). In addition, the air flow rate can be changed with a change in load.
(Dotted line 26).

According to the present invention, the function generator 81 of the arithmetic unit 8 is used.
Based on the characteristic of (83), the number of rotations of the shaft of the compressor is reduced, and the air flow rate is reduced. Therefore, the operating point R shown in FIG. For this reason, the internal efficiency of the compressor can be maintained high. In addition, since there is no restriction on the flow rate of the air sucked by the compressor, even in a low load range, it is possible to take in an air flow rate that is not too much or less than the fuel flow rate.

As a result, as shown by the characteristic 26 (dotted line) in FIG. 6, even in a low load region (partial load region), the temperature of the combustion gas at the inlet of the gas turbine does not decrease.
The thermal efficiency of the gas turbine can be maintained almost equal to that in the high load region. In other words, in a wide load range,
That is, even at the time of partial load, high thermal efficiency near the rated value can always be maintained.

As described above, in the gas turbine power generation equipment shown in this embodiment, an efficient equipment can be achieved.

Further, the present invention can be used in a combined cycle plant.

FIG. 7 shows a configuration diagram of a combined cycle plant. The main engine is composed of gas turbine equipment, steam turbine equipment, and a generator. In the embodiment shown in FIG. 7, an example is shown in which these three members are directly connected on one shaft. It may be a multi-shaft type having a separate generator.

The air 57 sucked by the compressor is compressed and becomes high-temperature and high-pressure gas in the combustor 2 and flows into the gas turbine 3. Here, a part of the heat energy is converted into work and converted into electric energy by the generator 5. The exhaust gas 55 from the gas turbine 3 heats the water supply 53 in the exhaust heat recovery boiler 51 to generate steam 54. The steam 54 is guided to the steam turbine 52 to perform work, and is converted into electric energy by the generator 5. The steam after work is returned to the water in the condenser 56, and is supplied again to the exhaust heat recovery boiler 51 as the water supply 53. The exhaust gas 57 exiting the exhaust heat recovery boiler 51 is led to a chimney. As described above, the combined cycle plant generates power by combining the gas turbine equipment and the steam turbine equipment, and therefore has high thermal efficiency.

The other reference numerals shown in the figure are the same as those used in FIG. 1, and their functions are almost the same.

A conventional combined cycle plant (system) combining a gas turbine facility and a steam turbine facility in which the shaft rotates at a constant speed has a problem that the efficiency is reduced when the operation is performed under a partial load. However, by employing the present invention, there is an effect that the rate (width) at which the efficiency decreases can be reduced.

Further, the gas turbine power generation device of the present invention
The ability of the equipment can be exhibited in summer as well as in winter.

[0081]

According to the present invention, the output of the gas turbine power generator can be kept as constant as possible in a range where the temperature changes in practical use. In addition, high thermal efficiency can be maintained during operation under a partial load.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing the arithmetic unit and the variable speed generator of FIG. 1 in detail.

FIG. 3 is a diagram illustrating the principle of the present invention.

FIG. 4 is a diagram showing a modification of the embodiment of FIG. 2;

FIG. 5 is a diagram showing characteristics of compressor efficiency during operation at a partial load according to the present invention.

FIG. 6 is a diagram showing a relationship between a load and an air flow rate or a gas turbine inlet temperature.

FIG. 7 is a diagram showing a configuration of a combined cycle plant using the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Combustor, 3 ... Gas turbine, 4
... Fuel supply device, 5 ... Variable speed generator, 6 ... Fuel control device, 7 ... Excitation control device, 8 ... Operation device, 9 ... AC excitation device, 18 ... Power system, Pd ... Load request signal, T ... Atmospheric temperature .

Claims (12)

[Claims] 1. A compressor for taking in and compressing air, a combustor for burning air and fuel compressed by the compressor, a gas turbine driven by combustion gas from the combustor, and a gas turbine and a shaft. And a generator coupled via a power generator, wherein a primary winding of the generator is connected to a power system and a secondary winding thereof is AC-excited. apparatus. 2. The gas turbine power generator according to claim 1, wherein a fuel control device for determining and controlling an amount of fuel supplied to the combustor based on a load request signal, and a load control signal and an atmospheric temperature. An excitation control device that adjusts the amount of AC excitation of the generator based on the gas turbine power generation device. 3. The gas turbine power generator according to claim 1, further comprising an AC exciting device that AC-excites a secondary winding of the generator. 4. A compressor for taking in and compressing air, a combustor for burning air and fuel compressed by the compressor, a gas turbine driven by combustion gas from the combustor, and a gas turbine and a shaft. And a generator coupled via a generator, wherein a primary winding of the generator is connected to a power system, a secondary winding of the generator is connected to an AC excitation device, and the combustor is A fuel control device that determines and controls the amount of fuel to be supplied based on the load request signal, and adjusts the AC excitation amount of the generator based on the amount of fuel and the atmospheric temperature determined by the fuel control device. A gas turbine power generation device comprising: an excitation control device. 5. A compressor that takes in and compresses air, a combustor that burns air and fuel compressed by the compressor, a gas turbine that is driven by combustion gas from the combustor, and a primary winding that uses electric power. A generator connected to a system and a secondary winding of which is AC-excited, wherein the gas turbine and the generator are a variable-speed gas turbine power generator connected via a shaft, A variable-speed gas turbine power generator that adjusts the amount of AC excitation of the generator based on the rotation of the generator and controls the rotation speed of the shaft. 6. A compressor takes in the air, compresses the compressed air, burns the compressed air and fuel in a combustor, drives a gas turbine using the burned gas, and passes through the gas turbine and a shaft. A method of operating a gas turbine generator that drives a coupled generator, wherein the excitation frequency for the generator is made variable according to the temperature of the atmosphere. 7. The atmosphere is taken in by a compressor and compressed, and the compressed air and fuel are burned in a combustor. A gas turbine is driven by using the burned gas, and the gas turbine and the shaft are driven. A method of operating a gas turbine power generator that drives a coupled generator, comprising: changing the rotation speed of a magnetic field of the generator according to output fluctuations of the gas turbine. Method. 8. A compressor takes in the air, compresses the compressed air, burns the compressed air and fuel in a combustor, drives a gas turbine using the burned gas, and drives the gas turbine through the gas turbine and a shaft. In a method of operating a gas turbine power generator that drives a coupled generator, an exciting frequency for the generator is controlled so that the output frequency of the generator is substantially constant even when the temperature of the atmosphere fluctuates. A method for operating a gas turbine power generator, characterized by the above-mentioned. 9. A compressor takes in the atmosphere, compresses the compressed air and burns the compressed air and fuel in a combustor, drives a gas turbine using the burned gas, and passes through the gas turbine and a shaft. A method for operating a variable speed gas turbine power generator that drives a generator, wherein a primary winding is connected to a power system and a secondary winding is AC-excited, wherein the output of the gas turbine is substantially constant. The method of operating a variable speed gas turbine power generator, wherein the amount of AC excitation of the secondary winding is set smaller when the temperature of the atmosphere is lower than when the temperature of the atmosphere is higher. 10. A gas turbine driven by combustion gas, a generator coupled to the gas turbine via a shaft, a primary winding connected to a power system, and a secondary winding AC-excited; A combined cycle plant comprising: a boiler for exchanging heat with exhaust gas from a steam generator; and a steam turbine driven by steam generated from the boiler. 11. The combined cycle plant according to claim 10, wherein the amount of AC excitation of said generator is adjusted based on a load request signal and an atmospheric temperature. 12. A compressor for taking in and compressing air, a combustor for burning air and fuel compressed by the compressor, a gas turbine driven by combustion gas from the combustor, and a gas turbine and a shaft. A gas turbine power generator having a generator coupled via a power generator, characterized in that it has means for making the system frequency from the generator substantially constant even when the rotation speed of the shaft changes. Gas turbine generator.