JPH05340205A - Controller for combined power generation plant - Google Patents

Abstract

PURPOSE:To permit the suitable following to the aimed load of a combined power generation plant by installing a function generator for adding the correction signal in consideration of the atmosphere temperature variation, for each load charge instruction given to a gas turbine control part, steam turbine control part and a boiler control part. CONSTITUTION:A unit master 51 is applied with an aimed load. Each power generator output demand instruction for a gas turbine and a steam turbine for the aimed load is outputted from the unit master 51 to a gas turbine control part 52 and a steam turbine control part 53. Further, each boiler control demand for the aimed load is outputted for the boiler control part 54. A function generator 67 generates the function which sets the load reduction portion generated by the rise of the atmosphere temperature. Even in the case where the atmosphere temperature rises, the gas turbine control part can always continue the speed load control. Accordingly, indepedent of the atmosphere temperature variation state, the suitable followup to the aimed load of the whole of the combined power generation plant is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined power generation plant which is a combination of an existing steam turbine plant / boiler plant and a new gas turbine plant. The present invention relates to a control device for a combined cycle power plant that favorably controls the load (output) of the entire plant.

[0002]

2. Description of the Related Art Recently, gas turbine plants and steam turbines
We are looking at a proposal for a repowering power plant as an improved type of a combined power plant (combined cycle plant) in which power efficiency is increased by combining with a bin plant.

In this repowering power plant, a gas turbine plant is newly added to an existing steam power generation facility (steam turbine plant / boiler plant), and
It belongs to the so-called exhaust gas re-combustion combined cycle in which the waste heat of the bin plant is used as the combustion air of the boiler plant, or the waste heat of the boiler plant of the existing steam power generation facility is used to preheat the feed water, and it has the following features: is doing.

First, the power generation efficiency can be improved by combining the existing power generation plant. The next feature is that a gas turbine is additionally installed, so the amount of power generated by the entire power plant can be increased. Another feature is that remodeling of the existing equipment can be reduced, so that repowering can be performed in a relatively short period of time. Considering the significant increase in power demand in recent years and the consequent decrease in the power reserve ratio of each power company, it is difficult to construct a new power plant as soon as possible to cope with it. A power plant is one of the effective means to solve these problems. Figure 3 shows an example of a repowering power plant that is a combined cycle of exhaust gas reheat type, with a gas turbine plant newly added to the conventional steam power plant.

A major difference from the conventional steam power plant is that a gas turbine plant GT including a compressor 20, a combustor 21, a gas turbine 22, a gas turbine generator 23, a gas damper 24, etc. is additionally installed. The exhaust heat of the gas turbine 22 is used as combustion air for the boiler 1, and a high pressure stack gas cooler 25 and a low pressure stack gas cooler 26 are provided for the purpose of lowering the temperature of the exhaust heat. It is a point.

Among the existing steam power generation plants, the steam turbine plant ST includes a high pressure steam turbine 3, an intermediate pressure steam turbine 7, a low pressure steam turbine 9, a condenser 11 and a low pressure water supply. It comprises heaters 14a, 14b, 14c, a deaerator 15, and high-pressure feed water heaters 18a, 18b, 18c. Boiler plant B
Consists of a boiler 1 and a reheater 5.

In the combined cycle power plant having such a structure, the steam generated from the boiler 1 is guided to the high pressure steam turbine 3 by the main steam pipe 2. The steam that has worked in the high-pressure steam turbine 3 reaches the reheater 5 of the boiler through the low-pressure reheat steam pipe 4. The steam heated by the reheater 5 is guided to the medium pressure steam turbine 7 by the high temperature reheat steam pipe 6, and the steam working in the medium pressure steam turbine 7 is low pressure by the crossover pipe 8. It is led to the steam turbine 9. Further, the steam that has worked in the low-pressure steam turbine 9 is guided to the condenser 11 and becomes condensed water. High pressure steam turbine 3, medium pressure steam turbine 7 and low pressure steam turbine 9 are connected to a generator 10,
Electricity is generated by the generator 10. The water that has been condensed by the condenser 11 is pressurized by the condensate pump 12, is passed through the condensate pipe 13, and is heated by the low-pressure feed water heaters 14a, 14b, and 14c, and the other is the low-pressure stack gas cooler. It is heated at -26 and reaches the deaerator 15. The water deaerated by the deaerator 15 is further pressurized by the water supply pump 17 via the water supply pipe 16, and then one of them is pressurized by the high-pressure water heaters 18a, 18b, 18c,
The other side is pressurized by the high pressure stack gas cooler 25, reaches the boiler 1 and repeats the above-mentioned cycle to generate electricity. Next, an example of a control system of a conventional repowering power plant is shown in FIG.

[0008] A big difference from the conventional steam power plant is that the gas turbine power plant is additionally installed.
A bin control unit is additionally provided, and operation is controlled by a command from the overall plant general control unit (hereinafter referred to as a unit master).

A target load is given to the unit master 51, and the unit master 51 instructs the gas turbine control unit 52 and the steam turbine control unit 53 to supply the gas turbine and the steam turbine to the target load, respectively. Of the generator output request command, and a boiler control demand for the target load is output to the boiler control unit (hereinafter referred to as a boiler master) 54. In the gas turbine control unit 52, the gas turbine output signal 31 which is a feedback signal is input, and an opening command signal is output to the gas turbine fuel flow rate control valve 38 to obtain a given output command value. .. Similarly, in the steam turbine control unit 53, the steam turbine output signal 32 which is a feedback signal is input,
An opening command signal is output to the steam turbine control valve 39 so that the output command value is given. Meanwhile, boiler master
In 54, in addition to the demand signal from the unit master 51,
After inputting the main steam pressure signal 30 and performing arithmetic processing, the boiler fuel control system 54, the feed water flow rate control system 57, the main steam temperature control system 56, the reacher (RH) steam temperature control unit 55, the IDF inlet draft control unit A control command signal is output to each control unit of 58. In the boiler fuel control unit 54, the required boiler fuel flow rate corresponding to the given demand signal is arithmetically processed, and the input fuel flow rate signal 33 is an opening command signal to the boiler fuel control valve 40 in order to obtain the required boiler fuel flow rate. Is output. In the water supply flow rate control unit 57, the requested water supply flow rate corresponding to the given demand signal is arithmetically processed, and the input water supply flow rate signal 36 is
Boiler water supply turbine (B
FP) An opening degree command signal is output to the flow rate control valve 43. In the main steam temperature control unit 56, the required main steam temperature corresponding to the given demand signal is arithmetically processed, and the input main steam temperature signal 35 is supplied to the main steam temperature spray control valve 42 to obtain the required main steam temperature. And an opening command signal is output. R
In the H steam temperature control unit 55, the required RH steam temperature corresponding to the given demand signal is arithmetically processed, and the input RH steam temperature signal 34 is changed to RH /
An angle command signal is output to the super heater (SH) gas damper 41. In the IDF entrance draft control unit 58,
The requested IDF entrance draft corresponding to the given demand signal is arithmetically processed, and the input IDF entrance draft signal 37
However, the opening command signal is output to the IDF moving blade to obtain the required IDF inlet draft.

By the way, a control circuit configuration of the unit master 51 is illustrated in more detail in FIG. The target load command signal given to the target load unit master is inputted to the change rate limiter 62, and is inputted to the adder 63 as a signal limited by the output change rate set value given in advance, while the AFC setting is made. The signal is added together and output.
Further, it is input to the adder 64, and on the other hand, addition processing is performed together with the governor free compensation signal, and as a plant whole load setting signal,
Is output. One of the whole plant load setting signals is input to the function generator 66, and the gas turbine generator load set value for the whole plant output signal is calculated and then output as a target output value to the gas turbine control unit 52. And input to the subtractor 65. The subtractor 65 subtracts the gas turbine generator load set value signal from the entire plant load setting signal, and sends it to the steam turbine control unit 53.
Output as a bin generator load setpoint signal. The function generator 66 is set with a function having a linear characteristic as shown in FIG. 6, and the gas turbine plant GT is
The output of is proportional to the output of the entire plant.

With the above control configuration, it is possible to simultaneously control the gas turbine generator output and the steam turbine generator output, and to control the boiler input amount commensurate with the entire plant load setting.

[0012]

However, in the above control device, the following problems occur in consideration of the characteristics of the gas turbine. That is, the gas turbine has the characteristic that, when the fuel flow rate is controlled so that the gas turbine inlet temperature is constant, the maximum power that can be generated decreases with an increase in atmospheric temperature. For this reason, in consideration of the fact that when the atmospheric temperature rises during load operation, the gas turbine inlet temperature rises, the gas turbine control unit is equipped with an exhaust gas temperature limiting circuit, which allows the gas turbine plant to operate. The amount of fuel added to the engine is limited.

Generally, in Japan, there are many cases in which an atmospheric temperature of 15 ° C. is a design condition for a gas turbine plant,
Especially in the summer, it is the current situation that the rated output cannot be obtained, and conversely, the maximum output is raised even a little by intentionally limiting the exhaust gas temperature at the expense of the gas turbine plant (reduction of service life). It is also being operated. Even in this case, the gas turbine plant limits the exhaust gas temperature due to the rise in the atmospheric temperature, so to speak, it is not affected by the system frequency, that is, it is not affected by the slight fluctuation of the gas turbine rotation speed. The control state becomes the same as the road limiter operating state. If the operation purpose of this combined cycle power plant is base speed operation,
Although no problem occurs, the automatic frequency control signal (hereinafter referred to as A
Considering the need to act to contribute to stabilization of the system frequency with cabana free (speed control) for continuation of control based on FC) and system frequency fluctuation,
In the current control system, when the exhaust gas temperature rises due to the rise in the atmospheric temperature and the exhaust gas temperature is in a restricted state, only the gas turbine control unit performs AFC and governor free control, which are necessary for system safe operation. There will be a problem that it will not function.

The present invention has been made in consideration of the above circumstances, and is a control device for a combined cycle power plant in which a control circuit such as an AFC or a governor free functioning for stable system operation functions even when the atmospheric temperature rises. It is intended to provide.

[0015]

The present invention is provided with a gas turbine plant, a steam turbine plant and a boiler plant, wherein exhaust heat of the gas turbine plant is supplied to the boiler plant as combustion air, and Of the combined cycle power plants that use the exhaust heat as preheat for the feed water, the gas turbine plant is the gas turbine
There is a bin control unit, a steam turbine control unit for the steam turbine plant, and a boiler control unit for the boiler plant.The gas turbine control unit, the steam turbine control unit, and the boiler control unit are In the control device of the combined power plant that receives the target load command from the overall plant integrated control unit and gives a load sharing command to each of the gas turbine plant, the steam turbine plant, and the boiler plant, from the overall plant integrated control unit It is characterized in that a function generator for adding a correction signal in consideration of a change in atmospheric temperature to a load sharing command given to each of the gas turbine control unit, the steam turbine control unit and the boiler control unit is provided.

[0016]

Since the newly-provided function generator is a function that sets the load drop amount caused by the increase in the atmospheric temperature, the function generator outputs the target load drop command signal as the atmospheric temperature rises, and the addition is performed. The load target value for the gas turbine is corrected by adding the gas turbine load target value to the gas turbine. Not only the increase in the atmospheric temperature but also the decrease in the atmospheric temperature has the same effect.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic control block diagram showing an embodiment of the present invention. The same components as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted. The difference between FIG. 1 and FIG. 5 is that
The point is that a function generator 67 using the atmospheric temperature as a reference signal and an adder 68 are newly provided to create correction control.

One of the plant whole load command signals output from the adder 64 is input to the function generator 66, and after calculating the gas turbine generator load set value for the plant whole load signal, the adder 68 After inputting together with the output signal of the function generator 67 using the atmospheric temperature as a reference signal, the addition process is performed by the adder 68, and as a gas turbine load command signal,
The output is output to the gas turbine control unit 52 and also input to the subtractor 65 together with the plant total load command, and then the subtraction process is performed and output to the steam turbine control unit 53 as a steam turbine load command signal. An example of setting characteristics of the function generator 67 is shown in FIG. The calculation is performed using the atmospheric temperature as a reference signal and the target load increasing / decreasing manipulated variable as an output signal.

Since the newly-provided function generator 67 is a function that sets the load drop amount caused by the rise of the atmospheric temperature, the gas turbine load command signal is added by the adder 68 with the rise of the atmospheric temperature. , A negative value is added, and a gas turbine target load command signal in consideration of a load drop command corresponding to an increase in atmospheric temperature is output to the gas turbine control unit 52. Even when the atmospheric temperature drops, the signal level acts in the opposite direction.

[0020]

As described above, according to the present invention, the target load setting on the gas turbine side takes into consideration the load drop command commensurate with the increase in the atmospheric temperature, so that the gas turbine can be operated even when the atmospheric temperature rises. The bin controller can always continue the speed load control, and as a result, the combined cycle power plant can preferably follow the target load of the entire plant regardless of the state of the atmospheric temperature change.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a plant overall control unit (unit master) according to the present invention.

FIG. 2 is a graph showing characteristics of a plant overall control unit (unit master) according to the present invention.

FIG. 3 is a schematic diagram showing a system of a combined cycle power plant.

FIG. 4 is a schematic block diagram showing a conventional control system for the entire plant.

FIG. 5 is a schematic block diagram showing a conventional plant overall control unit (unit master).

FIG. 6 is a graph showing the relationship between the gas turbine output and the overall plant output.

[Explanation of symbols]

 GT ... Gas turbine plant ST ... Steam turbine plant B ... Boiler plant 51 ... Plant overall control unit (unit master) 52 ... Gas turbine control unit 53 ... Steam turbine control unit 54 ... Boiler control unit (boiler master) ) 66 ... Function generator

Claims (1)

[Claims] 1. A gas turbine plant, a steam turbine plant, and a boiler plant are provided, the exhaust heat of the gas turbine plant is supplied to the boiler plant as combustion air, and the exhaust heat of the boiler plant is used as preheat of feed water. Of the combined power plants to be served, the gas turbine plant has a gas turbine control unit and a steam turbine
The bin plant has a steam turbine control unit, and the boiler plant has a boiler control unit.The gas turbine control unit, the steam turbine control unit, and the boiler control unit are controlled by the plant overall control unit. In the control device of the combined power generation plant that receives the load command to the gas turbine plant, the steam turbine plant, and the boiler plant in response to the target load command, the gas turbine control unit from the plant overall control unit,
A controller for a combined cycle power plant, comprising a function generator that adds a correction signal in consideration of a change in atmospheric temperature to a load sharing command given to each of a steam turbine control unit and a boiler control unit.