JP2021005923A - Control method for gas turbine power generation system, and control device - Google Patents

Abstract

To provide a control method for a gas turbine power generation system capable of sufficiently effectively utilizing power generation capability of a generator even in the case where output fluctuation occurs in a gas turbine engine, and a control device.SOLUTION: In a method for controlling a gas turbine power generation system (S) comprising a gas turbine engine (GT) and a synchronous generator (1) which is driven by the gas turbine engine, reactive power to be output from the generator is set at a value QA obtained by the following formula (1): QA=S100×{1-(Pn/S100)2}1/2 (1) (wherein Pn is a present value [kW] of the active power output which is output from the gas turbine engine, and S100 is rated apparent power [kVA] of the generator) in a range where a ratio R=Pn/S100 of the present value of active power output from the gas turbine engine with respect to rated apparent power of the generator is a predetermined value Rs<R≤1.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method and an apparatus for controlling a power generation system (hereinafter, referred to as "gas turbine power generation system") using a gas turbine engine as a prime mover.

As a power generation facility, a gas turbine power generation system in which a gas turbine engine as a prime mover and a synchronous generator driven by the gas turbine engine are combined is widely used (see, for example, Patent Documents 1 and 2). Conventionally, in a gas turbine power generation system, the reactive power output is controlled so that the power factor becomes constant.

Japanese Unexamined Patent Publication No. 2014-138462 Special Table 2017-506302

However, normally, the active power output of a gas turbine engine can fluctuate by about several tens of percent due to the influence of factors such as a change in intake air temperature. In that case, the rated output of the generator combined with this gas turbine engine will match the maximum active power output of the gas turbine engine, so the generator will operate during the period when the gas turbine engine operates in the output region lower than the maximum output. Performance (apparent power output capacity) cannot be fully utilized.

Therefore, in order to solve the above problems, an object of the present invention is a control method of a gas turbine power generation system capable of fully utilizing the power generation capacity of the generator even when the output of the gas turbine engine fluctuates. The purpose is to provide a control device.

In order to achieve the above object, the control method of the gas turbine power generation system according to the present invention controls a gas turbine power generation system including a gas turbine engine and a synchronous generator driven by the gas turbine engine. The way,
The range in which the ratio of the active power output of the gas turbine engine to the rated apparent power of the generator to the current value of the active power output R = P _n / S ₁₀₀ is a predetermined value Rs <R ≦ 1 for the reactive power output from the generator. In the following equation (1)
Q _A = S ₁₀₀ × {1- (P _n / S ₁₀₀ ) ² } ^1/2 (1)
(However, P _n is the current value [kW] of the active power output output from the gas turbine engine, and S ₁₀₀ is the rated apparent power [kVA] of the generator).
It includes setting the value Q _A obtained in.

Further, the control device for the gas turbine power generation system according to the present invention is
A device that controls a gas turbine power generation system including a gas turbine engine and a synchronous generator driven by the gas turbine engine.
An active power detector that detects the active power output of the gas turbine engine,
The range in which the ratio of the active power output of the gas turbine engine to the rated apparent power of the generator to the current value of the active power output R = P _n / S ₁₀₀ is a predetermined value Rs <R ≦ 1 for the reactive power output from the generator. In the following equation (1)

Q _A = S ₁₀₀ × {1- (P _n / S ₁₀₀ ) ² } ^1/2 (1)

(However, P _n is the current value [kW] of the active power output output from the gas turbine engine, and S ₁₀₀ is the rated apparent power [kVA] of the generator).
It comprises a reactive power control unit that sets the obtained value Q _A by.

According to this configuration, the output of the generator is controlled so that the apparent power becomes constant in the region where the active power output, which is the normal operating region of the gas turbine engine, is close to the maximum value (rated value). As a result, when the active power output of the gas turbine engine drops from the maximum value, the reduced amount can be output as the reactive power of the generator, so that the performance of the generator can be fully utilized. Furthermore, since this control method is not a conventional control that keeps the delay power factor constant, the maximum apparent power output (rated apparent power output) of the generator when the power factor of the generator is 1 is set to that of the gas turbine. It can be the same value as the maximum value of the active power output. That is, the rated output and physique of the generator to be adopted can be made smaller than the rated output of the gas turbine power generation system as compared with the conventional one.

As described above, according to the control method and control device of the gas turbine power generation system according to the present invention, it is possible to fully utilize the power generation capacity of the generator even when the output of the gas turbine engine fluctuates. ..

It is a block diagram which shows the schematic structure of the gas turbine power generation system to which the control method and the control device which concerns on one Embodiment of this invention are applied. It is a generator output possible curve diagram which shows the principle of the control method which concerns on one Embodiment of this invention in comparison with the prior art. It is a graph explaining the effect of the control method which concerns on one Embodiment of this invention. It is a block diagram which shows the schematic structure of the control device which concerns on one Embodiment of this invention.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. FIG. 1 shows a gas turbine power generation system S to which the control method and control device according to the first embodiment of the present invention are applied. This gas turbine power generation system S is a system that generates power by driving a generator using a gas turbine engine as a prime mover, and is driven by a gas turbine engine (hereinafter, simply referred to as "gas turbine") GT and a gas turbine GT. A synchronous generator (hereinafter, simply referred to as a “generator”) 1 and a control device 3 for controlling the generator 1 are provided. The generator 1 in this embodiment is, for example, a three-phase alternator.

The gas turbine GT compresses the working gas (air in this example) introduced from the outside by the compressor 5 and guides it to the combustor 7 as compressed air, injects fuel into the combustor 7 and burns it together with the compressed air. The turbine 9 is driven by the obtained high-temperature and high-pressure combustion gas. The rotation of the turbine 9 drives the generator 1 connected to the rotor 11. The electric power generated by the generator 1 in this way is supplied to the load L. The gas turbine power generation system S is, for example, a power generation system used as an emergency power source for equipment, and supplies power to the load L by the system S alone without being connected to a system power source.

Hereinafter, the control method by the control device 3 according to the present embodiment will be described in detail.

As shown in FIG. 2, in the control device 3, the ratio of the current value of the active power output of the gas turbine GT to the rated apparent power of the generator 1 R = P _n / S ₁₀₀ (hereinafter, this ratio is referred to as “gas turbine output ratio”. ”) Exceeds the predetermined value _RS (hereinafter, this predetermined value is referred to as the“ control boundary value ”) and the region below the control boundary value _RS according to different rules. Do. Specifically, in the region A1 in which the gas turbine output ratio R is larger than the control boundary value _RS and is 1 or less (hereinafter, referred to as “first region”), the generator 1 is set so that the apparent power is constant. Control and set the value of reactive power. That is, the control device 3 calculates the reactive power output from the generator 1 in the first region A1 by the following equation (1):
Q _A = S ₁₀₀ × {1- (P _n / S ₁₀₀ ) ² } ^1/2 (1)
(However, P _n is the current value [kW] of the active power output output from the gas turbine engine, and S ₁₀₀ is the rated apparent power [kVA] of the generator 1).
It is set to a value Q _A obtained in.

In the present embodiment, the control boundary value _RS is set to 0.85 in advance. The set value of the control boundary value _RS is not particularly limited, but when the invalid power is supplied from other equipment, it is preferably 0.95 or less in consideration of the margin. Further, it is preferable that the set value of the control boundary value _RS matches the power factor of the load L fed by the gas turbine power generation system S. From this viewpoint, it is more preferable that the control boundary value _RS is set in the range of 0.8 or more and 0.9 or less, which is generally adopted as the power factor of the load L.

Conventionally, in general, as indicated by a chain line L ₀ in FIG. 2, the entire range of the effective power output of the gas turbine, it has been performed a power factor constant control by the lagging power factor on the generator output. Typically, when power is supplied from a generator to a grid power source, the rated power factor of the generator is required to be the delay power factor. In that case, the generator whose rated apparent power (rated output point S _r0 ) is the value obtained by dividing the rated output of the gas turbine by the above rated power factor is selected. Therefore, some factor active power output of the gas turbine is actuated when reduced by (e.g., a change in intake air temperature as described below), the generator also inside the output enable curve (line L _X indicated by the two-dot chain _line) Therefore, the power generation capacity (rated apparent power) of the generator cannot be fully utilized. Further, the rated output required for the generator must be a value having a margin with respect to the rated output of the gas turbine, and the physique of the generator must be increased accordingly. For example, in the case of constant power factor control in which the rated power factor is 0.85 with the above-mentioned control boundary value _RS , the rated output of the generator is about 18% higher than the rated output of the gas turbine. ..

On the other hand, in the present embodiment, in the first region A1, the power factor is 1, and the rated output of the generator 1 is such that the rated apparent power of the generator 1 matches the rated output of the gas turbine GT. After setting the point S _r1 , the control is performed so that the apparent power of the generator 1 is not constant, but the power factor is constant. That is, the output point S ₁ of the generator 1, to set the value of the reactive power Q _A to move over the possible output curve L ₁ of the generator 1. When the power is not supplied to the system power supply as in the gas turbine power generation system S according to the present embodiment, such control is possible because the power factor of the system power supply is not restricted. By controlling the generator 1 in this way, the power generation capacity (rated apparent power) of the generator 1 is fully utilized, and when the active power output of the gas turbine GT decreases, the amount of the power is reduced. It becomes possible to output as.

In the present embodiment, as shown in the figure, the control device 3 has a constant reactive power in a region (hereinafter, referred to as “second region”) A2 in which the gas turbine output ratio R is equal to or less than the control boundary value _RS . A value obtained by constant reactive power control along the line L ₂ (value corresponding to the output point S ₂ ) and a value obtained by constant power factor control along the constant power factor line L ₃ (corresponding to the output point S ₃₎ . The value of the reactive power is set by selecting the lower value from). That is, the control device 3 uses the following equations (2) and (3) to convert the reactive power output from the generator 1 in the second region A2.
Q _B1 = Q _max (2)
(However, Q _max is the value of the reactive power when the gas turbine output ratio R = Rs in the equation (1)).
Q _B2 = (1-COS ² θ _p ) ^1/2 × P _n / COS θ _p (3)
(However, COSθ _p is a predetermined value of the power factor in the generator 1)
Set to the smaller of the two values Q _B1 and Q _B2 obtained in.

By performing such control in the second region A2 while performing the above-mentioned constant apparent power control in the first region A1 which is a normally assumed operating region, the active power output of the gas turbine GT is significantly increased due to some factor. When it decreases, the control method can be switched from the apparent power constant control to secure the required power factor.

In this embodiment, as will be described in detail later, a value directly detected from the output of the generator 1 is used as the current value of the active power output (hereinafter, referred to as “current active power value”). As the current active power value P _n , a value detected based on the temperature of the working gas (air in this example) sucked by the gas turbine GT may be used.

Generally, as the intake air temperature of the gas turbine GT changes throughout the year, the active power value output by the gas turbine GT fluctuates. Specifically, as the intake air temperature rises, the active power output value of the gas turbine GT decreases. The fluctuation range of the active power value due to such fluctuation of the intake air temperature may reach about 30%. Normally, in the operation of the gas turbine GT, a command value of active power corresponding to a fluctuation of the intake air temperature is set in advance, and feedback control is performed based on this command value. Therefore, the active power command value corresponding to the intake air temperature fluctuation may be used as the above-mentioned active power current value P _n . By controlling in this way, it is possible to simplify the process of controlling the apparent power constant of the reactive power and output the amount of the decrease in the active power value due to the fluctuation of the intake air temperature as the reactive power.

Specifically, for example, the gas turbine output value corresponding to the intake air temperature is measured by a preliminary test, and a correlation map or correlation formula between the intake air temperature and the gas turbine output is created to correspond to the measured intake air temperature. The current active power value P _n is used.

If there is no factor other than the intake air temperature that lowers the active power output of the gas turbine GT, the value directly detected from the output of the generator 1 as the current active power value and the setting command value corresponding to the intake air temperature are Since they are almost the same, the control results are also almost the same. If it is assumed in advance that the active power output will fluctuate due to the influence of factors other than the intake air temperature fluctuation, a correlation map or the like that also takes into consideration fluctuations based on the other factors may be prepared.

FIG. 3 shows, as an example, the output characteristics from the gas turbine power generation system S when the generator 1 is controlled based on the intake air temperature by the method according to the present embodiment described above. The figure also shows, as a comparative example, the output characteristics when constant power factor control is performed over the entire conventional range. In the figure, the vertical axis represents the gas turbine output (kW) when the maximum value of the active power output (kW) of the gas turbine GT (rated output when the intake air temperature is 0 ° C.) is 100. The ratio of the apparent power output (kVA) of each generator 1 according to the comparative example is shown. The horizontal axis in the figure shows the intake air temperature. The gas turbine output is the output (active power output) from the gas turbine power generation system S.

As described above, in the comparative example, the power factor of the generator 1 is constantly controlled over the entire range of 0 ° C to 40 ° C. On the other hand, in the embodiment, the apparent power constant control of the generator 1 is performed in the range of 0 ° C. to about 20 ° C. (first region A1 described above), and the range of about 20 ° C. to 40 ° C. (second described above). In the area A2), the control by the low power selection between the constant reactive power control and the constant power factor control (in this example, the constant power factor control by the low power factor control is performed over the entire second area A2).

As can be seen from the figure, in the comparative example, the maximum apparent power output (rated apparent power output) of the generator 1 is about 11% larger than the maximum value of the active power output of the gas turbine GT. In the embodiment, the maximum apparent power output (rated apparent power output) of the generator 1 can be set to the same value as the maximum value of the active power output of the gas turbine GT. In other words, by adopting the control method according to the present embodiment, the rated output of the generator 1 to be adopted can be reduced by about 11% in order to obtain the same active power output from the gas turbine power generation system S. Further, as is clear from the figure, in the range of the intake air temperature from 0 ° C. to about 20 ° C., the ratio of the gas turbine GT output to the apparent power output of the generator 1 is higher in the example than in the comparative example. Due to its large size, the gas turbine power generation system S can be operated with high efficiency.

Next, a configuration example of the control device 3 for executing the control method described above will be described.

As shown in FIG. 4, the control device 3 includes an active power detection unit 21 and an inactive power control unit 23. The active power detection unit 21 detects the current value of the active power output of the gas turbine GT. The reactive power control unit 23 determines the value of the reactive power output from the generator 1 based on the active power output value detected by the active power detection unit 21. In the present embodiment, the control device 3 also includes an ineffective power detection unit 25, a voltage detection unit 27, a current detection unit 29, a voltage setting unit 31, a voltage adjustment unit 33, and an excitation unit 35.

The voltage detection unit 27 detects the output voltage of the generator 1. The voltage detection unit 27 is configured as a voltage transformer in this example. The current detection unit 29 detects the output current of the generator 1. In this example, the current detection unit 29 is configured as an instrument transformer.

The reactive power detection unit 25 is connected to the voltage detection unit 27 and the current detection unit 29, and the output voltage value of the generator 1 input from the voltage detection unit 27 and the output of the generator 1 input from the current detection unit 29. The output value of the reactive power is detected from the current value. The active power detection unit 21 is connected to the voltage detection unit 27 and the current detection unit 29, and the output voltage value of the generator 1 input from the voltage detection unit 27 and the output of the generator 1 input from the current detection unit 29. The output value of active power is detected from the current value.

The reactive power control unit 23 includes a control parameter storage unit 41, a calculation unit 43, and an reactive power indicator unit 45.

The control parameter storage unit 41 has a rated apparent power value S _{100 of} the generator 1, a maximum reactive power value Q _max , and a control boundary value _RS , which are constant parameters necessary for executing the control method described above by the control device 3. , A predetermined value COSθ _p or the like of the power factor when the power factor is constantly controlled in the second region A2 is stored, and is output to the calculation unit 43 as needed. When the control is performed based on the intake air temperature described above, the correlation map between the intake air temperature and the active power output is also stored in the control parameter storage unit 41.

The calculation unit 43 uses any of the above equations (1) to (3) from the current value of the active power input from the active power detection unit 21 and the control parameters stored in the control parameter storage unit 41. The target values Q _A , Q _B1 and Q _B2 of the ineffective power are calculated, and the deviation between the ineffective power target value and the current value of the inactive power input from the ineffective power detection unit 25 is calculated. The reactive power indicator 45 sends a control command value based on the deviation of the reactive power calculated by the calculation unit 43 to the voltage setting unit 31.

The voltage setting unit 31 sets the output voltage of the generator 1 based on the command from the reactive power indicator unit 45. The voltage adjusting unit 33 adjusts the output voltage of the generator 1 based on the output voltage of the generator 1 set by the voltage setting unit 31. The exciting unit 35 excites the generator 1 in accordance with a command from the voltage adjusting unit 33.

According to the control method and control device 3 of the gas turbine power generation system S according to the present embodiment described above, the apparent power of the generator 1 is constant in the region where the active power output of the gas turbine GT is close to the maximum value. When the active power output of the gas turbine engine drops from the maximum value, the reduced amount can be output as the ineffective power of the generator 1, so that the performance of the generator 1 can be fully utilized. can do.

Further, since this control method is not the conventional control for keeping the delay power factor constant, the maximum apparent power output (rated apparent power output) of the generator 1 when the power factor of the generator 1 is 1 is set to gas. It can be the same value as the maximum value of the active power output of the turbine GT. That is, since the rated output and physique of the generator 1 to be adopted can be made smaller than the rated output of the gas turbine power generation system S as compared with the conventional one, the control method and the control device 3 are applied. The efficiency and miniaturization of the gas turbine power generation system S can be improved.

Further, as described above, in one embodiment of the present invention, the current value _Pn of the active power output may be detected based on the temperature of the working gas sucked by the gas turbine GT. The output of the gas turbine GT during rated operation may fluctuate by several tens of percent depending on the temperature of the working gas to be sucked. Normally, the output of the gas turbine GT is an active power command corresponding to the fluctuation of the working gas temperature set in advance. It is controlled based on the value. Therefore, by using this command value as the current value of the active power output, the process of controlling the apparent power constant of the active power is simplified, and the amount of decrease in the active power value due to the fluctuation of the working gas temperature is output as the active power. Will be possible.

In one embodiment of the present invention, the following equations (2) and (3) are applied to the reactive power output from the generator 1 in the range where the ratio R is 0 ≦ R ≦ Rs.
Q _B1 = Q _max (2)
(However, Q _max is the value of the reactive power when the ratio R = Rs in the equation (1))
Q _B2 = (1-COS ² θ _p ) ^1/2 × P _n / COS θ _p (3)
(However, COSθ _p is a predetermined value of the power factor in the generator 1)
You may set it to the smaller of the two values Q _B1 and Q _B2 obtained in. According to this configuration, when the active power output of the gas turbine GT drops significantly due to some factor, the control method is switched from the apparent power constant control to the reactive power constant control or the power factor constant control, and the required power factor is obtained. Can be secured.

In one embodiment of the present invention, the predetermined value Rs of the ratio R may be set in advance in the range of 0.8 or more and 0.95 or less. According to this configuration, the required power factor can be surely secured by adjusting the lower limit of the region where the apparent power constant control is performed to the power factor of a general load.

The gas turbine power generation system S according to the present invention includes a gas turbine GT, a synchronous generator 1 driven by the gas turbine GT, and the control device 3 for controlling the generator 1. According to this configuration, by adopting the control method and the control device having the above-mentioned effects, it is possible to improve the efficiency and miniaturize the gas turbine power generation system S.

As described above, the preferred embodiment of the present invention has been described with reference to the drawings, but various additions, changes or deletions can be made without departing from the spirit of the present invention. Therefore, such things are also included within the scope of the present invention.

1 Generator 3 Control device 21 Active power detection unit 23 Reactive power control unit GT Gas turbine engine S Gas turbine power generation system

Claims (9)

A method of controlling a gas turbine power generation system including a gas turbine engine and a synchronous generator driven by the gas turbine engine.
The range in which the ratio of the active power output of the gas turbine engine to the rated apparent power of the generator to the current value of the active power output R = P _n / S ₁₀₀ is a predetermined value Rs <R ≦ 1 for the reactive power output from the generator. In the following equation (1)
Q _A = S ₁₀₀ × {1- (P _n / S ₁₀₀ ) ² } ^1/2 (1)
(However, P _n is the current value [kW] of the active power output output from the gas turbine engine, and S ₁₀₀ is the rated apparent power [kVA] of the generator).
It includes setting the value Q _A obtained in,
How to control a gas turbine power generation system. In the control method according to claim 1,
A control method comprising detecting the current value P _n of the active power output based on the temperature of the working gas taken in by the gas turbine engine. In the control method according to claim 1 or 2,
The following equations (2) and (3) are applied to the reactive power output from the generator in the range where the ratio R is 0 ≦ R ≦ Rs.
Q _B1 = Q _max (2)
(However, Q _max is the value of the reactive power when the ratio R = Rs in the equation (1))
Q _B2 = (1-COS ² θ _p ) ^1/2 × P _n / COS θ _p (3)
(However, COSθ _p is a predetermined value of the power factor in the generator)
Including setting to the smaller of the two values Q _B1 and Q _B2 obtained in
Control method. The control method according to any one of claims 1 to 3, wherein the predetermined value Rs of the ratio R is set in advance in the range of 0.8 or more and 0.95 or less. A device that controls a gas turbine power generation system including a gas turbine engine and a synchronous generator driven by the gas turbine engine.
An active power detector that detects the active power output of the gas turbine engine,
The range in which the ratio of the active power output of the gas turbine engine to the rated apparent power of the generator to the current value of the active power output R = P _n / S ₁₀₀ is a predetermined value Rs <R ≦ 1 for the reactive power output from the generator. In the following equation (1)

Q _A = S ₁₀₀ × {1- (P _n / S ₁₀₀ ) ² } ^1/2 (1)

(However, P _n is the current value [kW] of the active power output output from the gas turbine engine, and S ₁₀₀ is the rated apparent power [kVA] of the generator).
Comprises a reactive power control unit that sets the obtained value Q _A by,
Control device for gas turbine power generation system. In the control device according to claim 5.
A control device in which the active power detection unit detects the current value _Pn based on the temperature of the working gas taken in by the gas turbine engine. In the control device according to claim 5 or 6.
The reactive power control unit
The following equations (2) and (3) are applied to the reactive power output from the generator in the range where the ratio R is 0 ≦ R ≦ Rs.
Q _B1 = Q _max (2)
(However, Q _max is the value of the reactive power when the ratio R = Rs in the equation (1))
Q _B2 = (1-COS ² θ _p ) ^1/2 × P _n / COS θ _p (3)
(However, COSθ _p is a predetermined value of the power factor in the generator)
A control device that sets the smaller of the two values Q _B1 and Q _B2 obtained in. In the control device according to any one of claims 5 to 7.
A control device in which a predetermined value Rs of the ratio R is set in advance in the range of 0.8 or more and 0.95 or less. With a gas turbine engine
A synchronous generator driven by the gas turbine engine and
The control device according to any one of claims 5 to 8, which controls the generator.
A gas turbine power generation system equipped with.

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