JPH0120763B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an operation control device for a power generation plant composed of a plurality of power generation units.

[Technical background of the invention]

Recently, multi-cycle power generation units have been developed with the aim of improving power generation efficiency. This power generation unit combines a gas turbine and a steam turbine, and uses the exhaust gas that has driven the gas turbine to drive the steam turbine, thereby making effective use of thermal energy. However, since this power generation unit has a small single unit capacity, it is necessary to configure a single power generation plant with multiple units for system operation. Furthermore, since this power generation plant has only recently been developed, its operation control system has not been completely established, but it is expected that it will take a control form that is quite different from conventional ones. For example, since individual power generation units can be started and stopped easily, this power generation plant is used for operational control with a wide range of load adjustment.

By the way, when a power generation plant is operated in a system, it is generally necessary to improve the ability to follow a central power supply command in order to stabilize the power system.
As mentioned above, the operation control system for a power generation plant consisting of multiple power generation units is still in the development stage, but in order to improve followability to the central power supply command, it is necessary to increase the maximum load change rate that each power generation unit can take. It is conceivable to control operation using the maximum amount of change that can increase or decrease the output load, which depends on the characteristics of the component equipment.

For example, now the rated load of this power plant is
100%, the maximum load change rate of each power generation unit in this power generation plant is 1%/min in terms of rated load,
The minimum load at which each power generation unit can continue operating is also 14% in terms of rated load, the current number of power generation units operating at rated load is 5, and the target power plant load is 50%, and this is set as 3 units. It shall be operated by a power generation unit. Under this condition, the first
As shown by curve A in the figure, five power generating units are simultaneously lowered from 100% rated load (time t ₁ ) to 70% load (time t ₂ ) at the maximum rate of change. Since the minimum load of each power generation unit is 14%, after the power generation plant has dropped to 70% load, the three power generation units are operated at 14% load as shown in curve B in the figure.
As shown by curve C in the figure, the load of the remaining two power generation units is lowered at the maximum load change rate. When the two power generating units each reach 4% load (time
t ₃ ), the power plant load becomes 50%. From then on,
The two power generation units that are scheduled to be shut down are each set to zero.
%, and the remaining three power generation units
Increase to 16.7%. In this way, it becomes possible to reduce the power plant load from 100% of the rated value to 50% at the maximum load rate. still,
In FIG. 1, curve B represents a load change state for one power generation unit that does not stop, and curve C represents a load change state for one power generation unit that stops.

[Problems with background technology]

However, according to the above method, the time shown in Figure 1
The rate of change in the power plant's load around t ₂ is no longer constant, creating a problem that hinders system operation. That is, the central power dispatch center knows the load change rate of each power generation plant in advance and issues load increase/decrease commands to each power generation plant based on this information to maintain the balance of supply and demand in the system. Therefore, if the load change rate changes while the power generation plant increases or decreases the load, the balance between demand and connection will be disrupted, causing a problem in which stable operation of the system cannot be maintained.

[Purpose of the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an operation control device for a power generation plant that allows a power generation plant consisting of a plurality of power generation units to increase or decrease the load at the maximum rate of change while keeping the rate of load change constant.

[Summary of the invention]

Therefore, in the present invention, the power generation units to be started and stopped are started and stopped at the maximum load change rate, while the remaining operating power generation units are started and stopped at the maximum load change rate R _M (%/min) of the power generation plant. This is the maximum amount of load change that a power generation plant consisting of multiple power generation units can increase or decrease as a total output load, and it changes depending on the operating status and conditions at the time.
The present invention is characterized in that the load adjustment operation is performed at a rate of change that satisfies the following formula.

R _M =L _I −L _F /l _i −l _f r _n (%/min) However, L _I : Power plant load at the start of load change (%) L _F : Target power plant load (%) l _i : Load Power generation unit load at the start of change (%) l _f : Minimum power generation unit load when the target power generation plant load is reached (%) r _n : Maximum power generation unit load change rate of the power generation unit (%/min) [Embodiments of the invention] No. Figure 2 shows a configuration diagram of an operation control device for a power generation plant according to an embodiment of the present invention, in which 1 is a target load power generation unit target value setter, 2 is a load change rate control device, and 3 is a load control device. , 4 is a power generation plant.

The load change rate control device 2 includes an input processing section 21, a maximum load change rate calculation section 22, a parameter storage section 23, and an output processing section 24. The target load power generation unit target value setting device 1 is input to the input processing section 21.
Data d representing the target number of power generation units in operation
1. Data d2 representing the target load of the power generation plant
and power generation unit start/stop specification data d3
However, power generation plant current load data d4 is inputted from the load control device 3, and furthermore, data d5 representing the number of power generation units currently in operation is inputted from the power generation plant 4 to be controlled. The maximum load change rate calculation unit 22 receives power generation plant target load data d2, power generation unit target operating number data d1, and power generation plant current load data d4 from the input processing unit 21.
Data d5 on the number of currently operating power generating units are transmitted, and power generating unit maximum load change rate data d6 and power generating unit maximum and minimum load limit value data d7 are transmitted from the parameter storage section 23. As a result, the maximum load change rate calculation section 22 sends the output processing section 24 the target load data d2 of the power generation plant, the target number of power generation units in operation d1, the current load data of the power generation plant d4, the data d5 of the number of power generation units currently in operation, and the maximum number of power generation units in operation. Load change rate data d6 and power plant maximum load change rate data d8 are transmitted. The output processing unit 24 outputs power generation plant target load setting data d9 and power generation plant load change rate setting data d10 to the target load setter 31 of the load control device 3, and outputs power generation unit increase/decrease setting data d10 to the power generation unit increase/decrease load control switch 33. It outputs a load command d11 and a power generation unit increase/decrease load control switching command d12. At this time, power generation unit start/stop designation data d3 is transmitted from the input processing section 21 to the output processing section 24.

The load control device 3 is composed of a target load setter 31, a proportional integrator 32, a plurality of power generation unit increase/decrease load control switchers 33, and two adders 34, 35. It is configured to control the current load, which is the output of the power generation plant 4, according to the power generation plant target load setting data d9 and the load change rate setting data d10. That is, the target load setter 31 uses the given power plant target load setting data d9.
A power generation plant load command d13 is generated from the load change rate setting data d10. Power generation plant current load data d4 is converted into power generation plant load command d13
To make it equal to , a difference calculation is performed in the adder 34 to generate power plant control deviation data d14. This deviation data d14 is integrated in the proportional integrator 32, and the power generation unit control command d
This generation unit control command d15 is generated.
The output d16 of the plurality of power generation units 41 is controlled by the adder 3 of the power generation unit load data d16.
The power generation plant output added by 5, that is, the power generation plant current load data d4, is converted into the power generation plant load command d13, which is the output of the target load setter 31.
to follow. When the power generation unit increase/decrease load control switch 33 is switched to the power generation unit increase/decrease load command d11 side, the output load d16 of the corresponding power generation unit 41 is set to the power generation unit increase/decrease load command d1.
1.

With the above configuration, the power generation plant target load data d2 of the target value setting device 1 is automatically or manually set by a command from the central power dispatch center. The target number of operating power generation units data d1 is generally determined based on the partial load efficiency curve of the power generation plant, the power generation unit start-up and stop losses, and the load curve of the power generation plant so that the overall efficiency of the power generation plant is maximized.

FIG. 3 shows a partial load efficiency curve for a power plant with multiple generating units. It is known that when there are multiple identical power generating units, the highest efficiency is achieved when the minimum number of operating power generating units is used and the load is distributed evenly. The figure assumes that the power generation plant is composed of five power generation units.

FIG. 4 shows an example of a power plant load curve.
The figure assumes that the load changes from 100% to 70% from time t ₁ to t ₂ , and from 70% to 100% again from time t ₃ to t ₄ . In this case 100%
Let us assume that the number of power generation units operating at maximum efficiency is 5, and the number of power generation units operating at maximum efficiency of 70% is 4. When lowering the load from 100% to 70% (t ₁ → t ₂ ), (1) Power generation units: 5 → 4 (one power generation unit stops) (2) Power generation units: 5 → 5 (power generation units stop) 1 unit does not stop) Which of the above cases should be selected is determined by comparing the efficiency of case (1) and case (2) at 70%, t ₂ → t ₃
time and start-up and stop losses of the power generation unit. By stopping one power generation unit,
It is better to select case (1) when the gain from improved operating efficiency from t ₂ → t ₃ exceeds the start-up and shutdown losses of the power plant, and in the opposite case, it is better to select case (2). In this way, the target number of power generation units is calculated as the output load of the power generation plant changes.

The power generation unit start/stop designation data d3 indicates that the number of power generation units currently in operation is less (more) than the target number of power generation units when the power generation plant is increasing (decreasing) load.
In other words, when starting (stopping) a power generating unit is required, which power generating unit is to be started (stopped) is specified. Which power generation unit is selected to be started (stopped) is determined by the cumulative operating time of the power generation unit, maintenance and inspection work, the number of times the power generation unit is started and stopped, and so on.

The target load data d2 of the power generation plant, the target number of power generation units in operation d1, the current power generation plant load data d4, and the data d5 of the number of power generation units currently in operation are stored in the input processing unit 21 so that they can be easily processed in the maximum load change rate calculation unit 22. After signal processing, the signal is transmitted to the calculation section 22 described above. In addition, power generation unit start/stop designation data d
3 is subjected to signal processing in the input processing unit 21 so that it is easily processed in the output processing unit 24, and then
It is transmitted to the output processing section 24 mentioned above.

The power generation unit maximum rate of change data d6 in the parameter storage section 23 is determined by the maximum load change rate operation of the power generation unit 41. The generating unit is operated within this rate of change. Moreover, the power generation unit maximum and minimum load control value data d7 in this storage section 23 are as follows:
Determined by power generation unit capacity, operational efficiency, and safe operation. Steady load operation of the power generation unit is
This is carried out within the range of this load limit value data d7.

The maximum load change rate calculation section 22 receives the target operating number of power generation units d1, power generation plant target load data d2, power generation plant current load data d4, current power generation unit operation number data d5, and the parameter storage section 23, which are input from the input processing section 21. Power generation unit maximum load change rate data d6 input from
Based on the power generation unit maximum and minimum load control value data d7, the power generation plant maximum load change rate R _M given by the following equation (1) is calculated.

R _M =L _I −L _F /l _i −l _f r _n (%/min) …(1) However, L _I : Power plant load at the start of load change (%) L _F : Target power plant load (%) l _i : Generating unit load at the start of load change (%) l _f : Minimum generating unit load when the target power generating plant load is reached (%) r _n : Maximum generating unit load change rate (%/min) where, L _I , The calculation method for L _F , l _i , l _F , and r _n will be explained.

(i) L _I : Power plant load at the start of load change (%) L _I is the power plant current load data d4 in Figure 2, which is input from the load control device 3 via the input processing section 21 in the figure. Ru.

(ii) L _F : Target power generation plant load (%) L _F is target load data d2 of the power generation plant shown in Fig. 2, and the target load and power generation unit target value setter are inputted via the input processing section 21 shown in the figure. It is input from 1.

(iii) l _i : Generation unit load at the start of load change (%) l _i = L _I /N _I However, L _I : Power generation plant load at the start of load change (%) N _I : Number of operating power generation units at the start of load change N _I is data d5 on the number of power generation units currently in operation shown in FIG. 2, which is input from the power generation plant 4 via the input processing section 21 shown in the figure.

(iv) l _f : Minimum power generation unit load (%) when the target power generation plant load is reached (a) When l _nio ≦L _F /N _I ≦l _nax , l _f =L _F /N _I …(2) However, L _F : Target power generation plant load (%) N _I : Number of operating power generation units at the start of load change l _nio (l _nax ): Minimum (maximum) load limit value of power generation units (%) l _nio (l _nax ) is the second This is the power generation unit maximum and minimum load limit value data d7 shown in the figure, and is stored in the parameter storage section 23.

(b) In the case of L _F /N _I <l _nio or L _F /N _I >l _nax , l _f = L _F −N _F ×l _nio (l _nax )/N _I −N _F …(3) However, L _F : Target power generation plant load (%) l _nio (l _nax ): Minimum (maximum) load limit value for power generation units N _I : Number of power generation units in operation at the start of load change N _F : Target number of power generation units in operation N _F is the second This is data d1 for the target number of power generation units in operation in the figure, and is input processing unit 2 in the figure.
The target load and power generation unit target value setter 1 are inputted via the power generation unit 1.

In addition, if the conditions of L _F /N _I <l _nio or L _F /N _I >l _nax are satisfied when the load is reduced (increased) at the power generation plant, it is necessary to stop (start) one or more power generation units. Therefore, N _I −
N _F ≠0.

(v) r _n : Maximum power generation unit load change rate of the power generation unit (%/min) r _n is the power generation unit maximum load change rate data d6 in Fig. 2, and is stored in the parameter storage section 23 in the same figure. There is.

Through (i) to (v) above, L _I , L _F , l _i , l _f and r _n are determined, and the above equation (1) is calculated. FIG. 5 is a flowchart summarizing the processing at this time.

Next, the output processing section 24 uses the power generation plant target load data d2 and the power generation plant maximum load change rate data d8 from the maximum load change rate calculation section 22 to generate the power generation plant target load setting data d9 and the power generation plant load change rate setting data. d10 is output to the target load setter 31 of the load control device 3, and the output load of the power generation plant is changed at the maximum load change rate. Further, the power generation unit increase/decrease load control switch 33 corresponding to the power generation unit 41 to be started or stopped is switched to the power generation unit increase/decrease load command data d11 side based on the power generation unit start/stop designation data d3 from the input processing section 21. , output processing section 2
4 to the power generation unit increase/decrease load control switch 3
To 3, power generation unit increase/decrease load control switching command data d
Outputs 12. Next, the output processing section 24 outputs the power generation unit increase/decrease load command data d11 to the power generation unit 41 corresponding to the power generation unit start/stop designation data d3, and controls the power generation unit 41 according to the power generation unit maximum load change rate data d6. Start, stop.

For example, to explain the case where the operation of the power generation plant 4 is controlled under the same conditions as explained in FIG. Data for specifying the stop of three power generating units 41 is given as data d1, 50% as target load data d2 of the power generating plant, and data for specifying the stop of two power generating units 41 as power generating unit start/stop command data d3. At the same time, from the power generation plant 4, the current number of power generation units data d5 is 5 units, and furthermore, from the load control device 3, the power generation plant current load data d4 is 100%.
is given.

The load change rate control device 2 uses these data d1~
d5 and the power generation unit maximum load change rate data d6 stored in advance in the parameter storage unit 23 is 1%/min, and the power generation unit maximum and minimum load limit value data d7 is 14%. The power generation plant maximum load change rate R _M is calculated based on the equation ) and outputted to the target load setter 31 as the power generation plant load change rate data d10.

That is, in order to reduce the output load of the power generation plant to the target load at the maximum load change rate _RM , first all the power generation units currently in operation are simultaneously lowered to the target load at the maximum load change rate _RN .
Next, the power generation unit to be stopped thereafter is stopped by lowering its output load at the maximum load change rate R _M of the power generation unit. On the other hand, it is conceivable that the power generation unit that is to continue operating for the rest of the time will reduce its output load by sharing the output load of the power generation unit that is to be stopped, and thereafter operate so as to maintain the target load.

However, a minimum load control value l _nio is determined for the power generation unit that must continue to operate, and it is not allowed to go below this value.

Therefore, when L _F /N _I = 50/5 = 10 < l _nio = 14, as shown in Fig. 6, the output load of the power plant is adjusted to the maximum value as shown by curve α without changing the rate of change during the process. In order to quickly reduce the load to the target load, the output load of the two power generation units that should be stopped is reduced at the maximum load change rate r _n as shown by the curve γ, while the remaining power generation units that should continue operation are forced to reach the target load. curve β so that each output load reaches the generating unit minimum load limit l _nio = 14%.
It is sufficient to change it linearly as shown in .

In this case, when the power generation units reach 50% of the target load, the three power generation units that should continue to operate will each have a load of 14%, so the two power generation units that should stop operating will each reach a load of 4%. It can be seen that That is, from equation (3) in (b) of (iv) above, the minimum load l _f of the power generation unit when the power generation plant reaches the target load is l _f =L _F −N _F ×l _nio /N _I −N _F =50-3×14/5-3=4
It is calculated as %.

When l _f = 4% is determined, the maximum load change rate of the power generation unit at this time is set in advance as r _n = 1 (%/min), so from the load change start time t ₁ to the time the target load is reached t ₃ The load change time until T = (t ₃ − _{t 1} )
= (l _i -l _f )/r _n = (20-4)/1 = 16 minutes.

If the load change time T is found, the maximum load change rate R _M of the power generation plant at this time is R _M =L _i −L _f /T=L _i −L _f /l _i −l _f・r _n =100− 50/20-4・1=50/16=3.125 is determined, and the load change rate control device 2 sets this power plant maximum load change rate R _M =3.125 (%/min) as the target power plant load change rate setting d10. Output to the setting device 31.

The target load setter 31 outputs the power plant load command data d13 by integrating the power plant load change rate data d10, and calculates the deviation from the power plant current load data d4 fed back from the power plant 4 to the proportional integrator 32. DePI
The calculated power generation unit control command d15 data is
The three power generation units 41 are connected via the power generation unit increase/decrease load control switch 33 which has been switched to the d15 side.
Add to. At the same time, a power generation unit increase/decrease load control switching command d12 is outputted based on the power generation unit start/stop command d3 to select two power generation units increase/decrease load control switch 33 to be stopped among the five power generation units 41 currently in operation. is switched to the d11 side, and the power generation unit maximum load change rate data d6, that is, 1%/min, is outputted as the power generation unit increase/decrease load command d11, and the two predetermined power generation units 41 are stopped.

As a result, the load curve of power plant 4 changes linearly from 100% load to 50% load, as shown by α in Figure 6.
The load decreases at the maximum load change rate towards the load. That is,
The two power generation units 41 each follow the curve γ in the same figure.
As shown, the load decreases at a maximum load change rate of 1%/min from time _t1 . On the other hand, the remaining three power generation units 41
is a curve β such that the power plant 4 output d4 drops at the maximum load change rate R _M calculated by the above equation (1).
descend along the

Next, when the output d4 of the power generation plant 4 reaches 50% load, the load control device 3 adjusts the current load of the power generation plant based on the power generation plant target load setting data d9 output from the output processing unit 24 of the load change rate control device 2. Data d4 indicates that power plant 4 is this 50
3 power generation units 41 to maintain the % load.
control the load.

As a result, after each of the three power generation units 41 reaches 14% at time _t3 , as shown by the curve β in FIG.
1 decreases along the curve γ from 4% (time t ₃ ) to 0% (time t ₄ ), and increases to 16.7%.

In this way, the load of the power generation plant 4 is reduced to the first
As in the case shown in the figure, the maximum load change rate can be reduced from 100% to 50% from time t ₁ to t ₃ , and it can be reduced linearly during that time, so the power generation consisting of multiple power generation units This enables smooth and stable plant system operation.

In other words, if we compare this with the conventional example explained in Figure 1, we can reduce the power plant load from 100% to 50%.
% remains unchanged at t ₃ − t ₁ = 16 minutes, but in the conventional case, the load changes around time t ₂ .
Whereas R _M varies, in the case of the present invention, the load change rate R _M is constant, contributing to smooth and stable system operation.

By making it possible to change the power generation unit maximum load change rate data d6 stored in the parameter storage section 23 of the load change rate control device 2 from the outside, thermal stress management of the gas turbine and steam turbine of the power generation unit 41 is facilitated. It can be done. That is, the lifespan of gas turbines and steam turbines is generally managed by the integrated value of thermal stress generated as a result of load fluctuations in the power generation unit. The greater the rate of change in power generation unit load, the greater the thermal stress generated due to the load change. Therefore, by making the maximum load change rate of the power generation unit variable, it is possible to easily manage the thermal stress of the gas turbine and steam turbine.

〔Effect of the invention〕

As described above, according to the present invention, the output load of a power generation plant consisting of a plurality of power generation units can be made linear and controlled at the maximum load change rate. As a result, the ability to follow load change commands from the central power dispatch center is improved, and a power generation plant with high load adjustment ability useful for stabilizing the power system can be obtained.

[Brief explanation of drawings]

Figure 1 is a load curve diagram of a power generation plant consisting of multiple power generation units, Figure 2 is a block configuration diagram of an operation control device for a power generation plant according to an embodiment of the present invention, and Figure 3 is a diagram of a power generation plant consisting of multiple power generation units. Fig. 4 is a partial load efficiency curve diagram, Fig. 4 is a power generation plant load curve diagram, Fig. 5 is a flowchart of processing in the load change rate control device in Fig. 2, and Fig. 6 is a diagram of maximum load change rate control in Fig. 2. It is a load curve diagram for explaining an example. 1...Target load power generation unit target value setting device, 2
...Load change rate control device, 3...Load control device,
4...Power plant, 21...Input processing section, 22
... Maximum load change rate calculation section, 23 ... Parameter storage section, 24 ... Output processing section, 31 ... Target load setter, 32 ... Proportional integrator, 33 ... Power generation unit increase/decrease load control switch, 34 , 35... adder, 41... power generation unit.

Claims (1)

[Scope of Claims] 1. In an operation control device for a power generation plant consisting of a plurality of power generation units, a parameter storage unit that stores maximum and minimum load limit values of the power generation unit and maximum load change rate of the power generation unit, and a target of the power generation plant. an input processing unit for inputting the load, the target number of power generation units in operation, the current load of the power generation plant, and the number of power generation units currently in operation; the parameter storage unit;
Based on the data from the input processing section, calculate the maximum load change rate R _M of the power plant R _M =L _I −L _F /l _i −l _f r _n (%/min) where, L _I : Current load of the power plant (%) L _F : Target load of power generation plant (%) l _i : Power generation unit load at the start of power generation plant load change (%) l _f : Minimum power generation unit load (%) when power generation plant target load is reached r _n : Maximum power generation unit A maximum load change rate calculation unit that calculates the load change rate (%/min), an output process that outputs the power generation plant maximum load change rate, power generation plant target load, power generation unit maximum load change rate, and power generation unit increase/decrease load control switching command. A load change rate control device consisting of each part of the unit and the power generation unit to be started or stopped based on the increase/decrease load control switching command are started or stopped at the maximum load change rate of the power generation unit, and at the same time, the power generation unit is started or stopped at the maximum load change rate of the power generation plant. A power generation plant operation control device comprising: a load control device that controls a power generation unit remaining in operation according to a rate of change and a target load of the power generation plant.