JP2000297608A - Control device for feed water pump of power station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a feed water pump of a power station that can control water supply stable, when fast cut back(FCB) occurs. SOLUTION: A speed deviation, which is based on a speed setting value output by a water supply control device 32 and a speed detected value, is input into a steam pressure control device 34. The steam pressure control device 34 outputs a steam pressure control signal according to the speed direction and adjusts an opening degree of a low-pressure adjusting valve 8 and a high- pressure adjusting valve 9 using a hydraulic servo 38. A function generation device 35 inputs a header pressure of a boiler 1 detected by a pressure detection device 13 and sends a preliminary steam control signal to the steam pressure control device 34 via a switch 36. When FCB occurs, the opening degree position of the high-pressure adjusting valve 9 is set according to the loaded condition of a generator, that is, pressure condition of the boiler header.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply pump control device for a power plant for supplying water to a steam generator which generates steam to be a driving source of a main steam turbine for driving a generator.

[0002]

2. Description of the Related Art A feed pump for a boiler in a thermal power plant or a feed pump for a nuclear reactor in a nuclear power plant is driven by a feed turbine operated by steam which is a driving source of a main steam turbine for driving a generator. ing.

In order to drive a feedwater pump by a feedwater turbine, a deviation between a detected value of the rotation speed of the feedwater turbine and a set speed value of the feedwater turbine associated with a required value of a feedwater flow rate for the steam generator is determined. The flow rate of steam supplied to the water supply turbine is controlled by a steam pressure control signal that suppresses the above, and water is supplied from the water supply pump to the steam generator.

[0004] Steam is supplied to a water supply turbine from two systems, a bleed air supply piping system and a main steam supply piping system.
The opening degree of the low-pressure control valve and the high-pressure control valve arranged in these two systems is adjusted in accordance with the required value of the feedwater flow rate to maintain the rotation speed of the feedwater turbine at a set value.

In the case of a power plant, when an accident occurs in a transmission line system or the like, the generator is disconnected from the system, and the power generation output is instantaneously reduced to the in-house auxiliary electric power equivalent to several percent of the normal operation. A so-called Fast Cut Back (hereinafter, referred to as FCB) operation for lowering is performed.

When the operation of the power plant shifts to FCB operation,
Since the main steam turbine is also in the no-load operation state for a short time, the boiler input such as water supply, fuel, and air to the boiler is set to be rapidly reduced to the minimum load of the boiler, and the operation is shifted to the in-house single load operation.

When the operation shifts to the FCB operation, the pressure of steam serving as a driving source for driving the main steam turbine rapidly decreases, and the pressure of the bleed air of the main steam turbine also sharply decreases. Therefore, a feedwater turbine that normally uses bleed air as a drive source needs to use main steam as a drive source during FCB operation. That is, the feedwater turbine can be normally driven by low-pressure bleed air. However, during FCB operation, unless driven by steam from the main steam supply system to which high-pressure steam is supplied, the rotation speed of the feedwater turbine decreases, and Cannot be obtained.

In order to solve such a problem, for example, as described in Japanese Patent Publication No. 2-56481, when the FCB is generated, the high pressure control valve is forcibly opened to a fixed opening position. I have.

[0009]

The header pressure (outlet pressure of the feedwater pump) of the steam generator after FCB generation differs from the plant operation state immediately before FCB generation, that is, the generator load state. While the operating time constant of the steam generator is relatively large, the speed of the feed water pump is also rapidly reduced because the extracted steam of the feed water turbine is rapidly reduced. Therefore, F
There is a problem that the water supply control cannot be stably continued without the water supply flow rate temporarily becoming zero or excessive flow rate depending on the generator load state when CB occurs, that is, the boiler header pressure state.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a water supply pump control device for a power plant which can continue water supply control stably when FCB occurs.

[0011]

A feature of the present invention is that the opening position of the high-pressure control valve is determined by the generator load state, that is, the boiler header pressure state when FCB occurs.

According to the present invention, when the FCB is generated, the opening position of the high-pressure regulator valve is determined by the generator load state, that is, the boiler header pressure state, so that the water supply flow rate is stabilized without temporarily becoming zero or excessive flow rate. Water supply control can be continued.

[0013]

FIG. 1 shows an embodiment of the present invention.

In FIG. 1, a boiler (steam generator) 1
The high-pressure turbine 3A and the medium-pressure turbine 3
B, which is supplied to the low-pressure turbine 3C to drive the generator 2; A reheater 4 and an intercept valve 5 are provided between the high-pressure turbine 3A and the intermediate-pressure turbine 3B. The illustration of the main steam control valve and the like is omitted.

The boiler 1 has a water supply pump 6 and an outlet valve 10.
Water is supplied via A plurality of water supply pumps are provided for turbine drive and electric drive, but only one for water supply is shown. The outlet pressure of the water supply pump 6 (header pressure of the boiler 1) is detected by the pressure detector 13. The feedwater pump 6 is driven by a feedwater turbine 7.

The water supply turbine 7 extracts air from the high-pressure turbine 3 A and extracts air at the outlet of the reheater 4.
The main steam is supplied via a high pressure control valve 9 from a main steam supply piping system 9 which takes in the main steam supplied to the high pressure turbine 3A from the boiler 1 while supplying the extracted steam via the low pressure control valve 8.

A gear 22 is mechanically connected to a drive shaft of the water supply turbine 7. The speed detectors 18 and 20 are gears 22
The rotation speed of the water supply turbine 7 is detected based on the rotation speed of.
The speed detection signals detected by the speed detectors 18 and 20 are converted by signal converters 24 and 26, respectively, and input to a signal selector 28.

The signal selector 28 selects a speed detection value regarded as a true value from the two speed detection signals detected by the speed detectors 18 and 20. Specifically, if the difference between the two signals is within the allowable value, a high value is regarded as a true value, and if the difference is outside the allowable value, a smaller change rate is regarded as a true value and selected.

The water supply control unit 32 outputs a speed set value of the water supply turbine 7 based on a required value of a flow rate of the water supply to the boiler 1. Speed setting value of water supply control device 32 and signal selector 2
The detected speed value selected in 8 is added to the adder 30 with the polarity shown in the figure to obtain a speed deviation, which is input to the vapor pressure controller 34.

The steam pressure control unit 34 outputs a steam pressure control signal corresponding to the speed deviation to adjust the hydraulic level of the hydraulic servo 38. As the vapor pressure control device 34, a device that performs a proportional / integral compensation operation is used. The hydraulic servo 38 operates the link mechanism 40 by hydraulic pressure to operate the opening of the low pressure control valve 8 and the high pressure control valve 9. The hydraulic servo 38 and the link mechanism 40 constitute an adjustable valve driving device.

The function generator 35 inputs the header pressure Hb of the boiler 1 detected by the pressure detector 13 and applies a preliminary vapor pressure control signal to the vapor pressure controller 34 via the switch 36. The switch 36 is turned on when an FCB occurs.

Next, the operation will be described.

In the normal operation of the generator 2, the water supply control device 32
The speed deviation between the speed set value and the speed detection value obtained from the signal selector 28 is input to the vapor pressure control device 34. An operation for suppressing a speed deviation from the vapor pressure control device 34 adder 30 is performed, and a vapor pressure control signal according to the operation value is applied to the hydraulic servo 42.

The hydraulic servo 42 changes the hydraulic servo level based on the vapor pressure control signal. The link structure 44 operates according to the hydraulic servo level of the hydraulic servo 42 to control the opening of the low-pressure control valve 8 and the high-pressure control valve 9. Low pressure control valve 8
The flow rate of steam supplied from the bleed air supply piping system 11 and the main steam supply piping system 12 to the water supply turbine 7 is varied by controlling the opening degree of the high-pressure control valve 9.

The low pressure control valve 8 and the high pressure control valve 9 are controlled by the hydraulic servo level of the hydraulic servo 38 as shown in FIG. That is, when the hydraulic servo level is in the range of 0% to a%, the opening of the low pressure control valve 8 is 0% to 100%, and the steam amount at that time changes according to the characteristic A. When the hydraulic servo level exceeds a%, the high-pressure control valve 9 starts to open, and when the hydraulic servo level is in the range of a% to 100%, the opening of the high-pressure control valve 48 becomes 0% to 100%, and the steam amount depends on the characteristic B. Change.

After the low pressure control valve 8 is fully opened, the high pressure control valve 9 is opened. When the hydraulic servo level of the hydraulic servo 38 reaches 100%, the steam amount C + the steam amount D
Is supplied to the feedwater turbine 12.

During normal operation of the generator 2, the amount of steam supplied to the water supply turbine 12 is adjusted by the low pressure reducing valve 8.
Adjustment by the high-pressure control valve 9 is performed when FCB occurs.

When the turbine speed is changed by adjusting the amount of steam supplied to the feedwater turbine 12 in this manner, the relationship between the outlet pressure Hp of the feedwater pump 6 and the feedwater flow rate Q is as shown in FIG. At that time, the boiler header pressure Hb
Are as shown in the characteristics shown.

FIG. 4 shows the relationship between the flow rate Q of water supplied to the boiler 1 from the water supply pump 6 driven by the water supply turbine 7 and the power output (generator load) of the generator 2. The relationship between the boiler header pressure Hb and the generator load is as shown in FIG.

Next, the operation when the FCB occurs will be described.

The function generator 35 has a function having the characteristics shown in FIG. The switch 36 is turned on when an FCB occurs. The function generator 35 receives the boiler header pressure Hb detected by the pressure detector 13 and applies a preliminary steam pressure control signal proportional to the boiler header pressure Hb to the steam pressure controller 34 as shown in FIG.

Upon input of the preliminary vapor pressure control signal, the vapor pressure control unit 34 increases the integral term thereof in proportion to the magnitude of the preliminary vapor pressure control signal and converts the vapor pressure control signal shown in FIG. This is given to the servo 42. When the hydraulic servo level of the hydraulic servo 38 exceeds a% shown in FIG. 2, the low pressure control valve 8 is fully opened and the high pressure control valve 9 is opened. As shown in FIG. 6C, the high-pressure control valve 9 is opened to an opening position corresponding to the boiler header pressure Hb when the FCB is generated. FIG. 6 (b)
Shows that the occurrence of FCB was detected.

The generation of FCB causes the steam pressure in the bleed air supply piping system 11 to drop sharply, and the main steam is supplied to the water supply turbine 7 from the main steam supply piping system 12 through the high pressure control valve 9. The water supply turbine 7 is supplied with the steam amount by the steam pressure based on the speed set value set by the water supply control device 32 and the steam pressure based on the boiler header pressure Hb by the function generator 35.

As is clear from the characteristics of FIG. 5, the opening position of the high-pressure control valve 9 when FCB is generated increases as the generator load increases. FIG. 7 shows that the opening (hydraulic servo level) increases by α% when the generator load is 50%. On the other hand, FIG. 8 shows that the generator load is 100 and increases by β%. As can be understood from FIGS. 7 and 8, β is larger than α.

The water supply pump 6 is controlled as described above, and the difference between the operation and the effect when the opening position of the high-pressure control valve 9 is fixed will be described.

FIG. 9 shows the feed water flow rate Q and the header pressure (H
FIG. 4 is a characteristic diagram showing a relationship between p, Hb) and a generator load.

In FIG. 9, FCB is generated during operation with the load L1, and the boiler 1 side feedwater flow rate Q1 is requested immediately after the FCB is generated.
When the opening is fixed to, the water supply is temporarily disabled. Conversely, when operating with the load L2, FCB is generated and FC
Immediately after the occurrence of B, the boiler 1 side water supply flow rate Q2 is requested, but when the high pressure control valve 9 is fixed at the opening of the flow rate Q1, the flow temporarily becomes excessive.

The reason why the water supply is not possible or the flow rate is excessive is the relationship between the inlet pressure of the water supply pump 6 and the boiler header pressure, which depends on the rotation speed of the water supply turbine 7.

FIGS. 10, 11 and 12 show the characteristics of the inlet pressure, the boiler header pressure Hb and the flow rate Q of the feed water pump 6 simulated by the present inventors.

FIG. 10 shows the characteristics of FCB generation when the load is 50%. The prior art shown in FIG. 10A and the present invention shown in FIG. 10B are almost the same. FIG. 11 shows the characteristics of FCB generation when the load is 100%.
In contrast to the present invention shown in FIG. 11B, in the prior art shown in FIG. 11A, the water supply flow rate Q is temporarily zero. further,
FIG. 12 shows FCB generation characteristics when the load is 25%.
In contrast to the present invention shown in FIG. 2 (b), in the prior art shown in FIG. 12 (a), the supply water flow rate Q temporarily becomes excessive.

As described above, according to the present invention, the water supply flow rate does not temporarily become zero or excessive flow rate because the high pressure regulator valve is opened at the time of FCB generation depending on the generator load state, that is, the boiler header pressure state. Water supply control can be stably continued. As a result, the runback of the boiler can be performed stably.

FIG. 13 shows another embodiment of the present invention.

The embodiment of FIG. 13 differs from that of FIG. 1 in that the power output of the generator 2 is detected by a power detector 42 and is applied to a function generator 35.

Also in the embodiment shown in FIG. 13, as is clear from the characteristics shown in FIG. 5, the water supply control can be stably continued without the water supply flow rate temporarily becoming zero or excessive flow rate.

The feedwater turbine, that is, the feedwater pump is controlled as described above. However, when the FCB is generated, the opening position of the high-pressure regulator valve is determined by the generator load state, that is, the boiler header pressure state. Water supply control can be stably continued without temporarily becoming zero or overflow.

Further, the above-described embodiment has an effect that it can be easily realized without providing any new device.

[0047]

As described above, according to the present invention, F
When the CB occurs, the opening position of the high-pressure control valve is determined by the generator load state, that is, the boiler header pressure state, so that the water supply control can be stably continued without the water supply flow rate temporarily becoming zero or excessive flow rate. As a result, the runback of the boiler can be performed stably.

[Brief description of the drawings]

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

FIG. 2 is a characteristic diagram showing a relationship between a hydraulic servo level and a steam amount.

FIG. 3 is a characteristic diagram for explaining the operation of the present invention.

FIG. 4 is a characteristic diagram for explaining the operation of the present invention.

FIG. 5 is a characteristic diagram for explaining the operation of the present invention.

FIG. 6 is a characteristic diagram for explaining the operation of the present invention.

FIG. 7 is a characteristic diagram for explaining the operation of the present invention.

FIG. 8 is a characteristic diagram for explaining the operation of the present invention.

FIG. 9 is a characteristic diagram for explaining a problem of the related art.

FIG. 10 is a characteristic diagram for explaining the effect of the present invention.

FIG. 11 is a characteristic diagram for explaining the effect of the present invention.

FIG. 12 is a characteristic diagram for explaining the effect of the present invention.

FIG. 13 is a configuration diagram showing another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Boiler, 2 ... Generator, 3 ... Main steam turbine, 6 ... Water supply pump, 7 ... Water supply turbine, 8 ... Low pressure control valve, 9 ... High pressure control valve, 18, 20 ... Speed detector 32 ... Water supply control device, 34: vapor pressure control device, 35: function generator, 38: hydraulic servo, 11: bleed supply piping system,
12 ... Main steam supply piping system

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shintaro Tsuji 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture Inside the Omika Plant, Hitachi, Ltd. (72) Inventor Takashi Tomura 5-chome, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 Inside the Omika Plant of Hitachi, Ltd.

Claims (5)

[Claims] 1. A main steam turbine for driving a generator, a steam generator for generating steam to be supplied to the main steam turbine, a water supply turbine for driving a water supply pump for supplying water to the steam generator, and the main steam A low-pressure regulator that supplies extracted steam extracted from the turbine to the feedwater turbine; a high-pressure regulator that supplies main steam generated by the steam generator to the feedwater turbine; and a speed detector that detects a rotation speed of the feedwater turbine. Means, a feedwater flow rate control means for outputting a speed set value based on a feedwater flow rate to be supplied to the steam generator, and a deviation between the speed set value and the speed detection value detected by the speed detection means, and inputting a steam pressure. A control signal that outputs a control signal to open the high-pressure control valve after the low-pressure control valve is fully opened; and a low-pressure control valve that receives the steam pressure control signal to input the steam pressure control signal. Valve drive means for opening and closing the control valve, and a reserve steam pressure control signal based on the header pressure of the steam generator when the load of the generator is cut off, to the steam pressure control means to reserve the opening of the high pressure control valve. A feed water pump control device for a power plant, comprising: a preliminary steam pressure control signal generating means for setting an opening degree based on the steam pressure control signal. 2. A main steam turbine for driving a generator, a steam generator for generating steam to be supplied to the main steam turbine, a feedwater turbine for driving a feedwater pump for supplying water to the steam generator, and the main steam. A low-pressure regulator that supplies low-pressure steam extracted from the turbine to the feedwater turbine; a high-pressure regulator that supplies high-pressure steam input to the main steam turbine to the feedwater turbine; and a speed detector that detects a rotation speed of the feedwater turbine. Means, a feedwater flow rate control means for outputting a speed set value based on the feedwater flow rate requested by the steam generator, and a deviation between the set speed value and the detected speed value detected by the speed detection means, and inputting a steam pressure. A control signal that outputs a control signal to open the high-pressure control valve after the low-pressure control valve is fully opened; and Valve driving means for opening and closing the high-pressure control valve, and applying a preliminary steam pressure control signal based on the power generation output of the generator to the steam pressure control means at the time of fast cutback of the generator to adjust the opening degree of the high-pressure control valve. A feed water pump control device for a power plant, comprising: a pre-steam pressure control signal generating means for setting an opening position based on the pre-steam pressure control signal. 3. A main steam turbine for driving a generator, a steam generator for generating steam to be supplied to the main steam turbine, a feedwater turbine for driving a feedwater pump for supplying water to the steam generator, and the main steam. A low-pressure regulator that supplies extracted steam extracted from the turbine to the feedwater turbine, a high-pressure regulator that supplies main steam generated by the steam generator to the feedwater turbine, and a speed detector that detects a rotation speed of the feedwater turbine Means, a feedwater flow rate control means for outputting a speed set value based on a feedwater flow rate supplied to the steam generating device, and a deviation between the speed set value and the speed detection value detected by the speed detection means, and A steam pressure control means for performing an integral compensation operation, outputting a steam pressure control signal, opening the high pressure control valve after fully opening the low pressure control valve, and inputting the steam pressure control signal. Servo drive means for opening and closing the low-pressure control valve and the high-pressure control valve; and providing a preliminary steam pressure control signal based on the outlet pressure of the feed water pump to the steam pressure control means when the load of the generator is cut off, to thereby provide an integral output. A feed steam pump control device for a power plant, comprising: a means for generating a pre-steam pressure control signal for increasing the opening of the high-pressure control valve to an open position based on the pre-steam pressure control signal. 4. A main steam turbine having a plurality of stages of turbines having different pressures for driving a generator, a boiler for generating steam to be supplied to the main steam turbine, and a feedwater pump for supplying water to the boiler , A low-pressure regulator that supplies extracted steam extracted from the main steam turbine to the water turbine, a high-pressure regulator that supplies main steam generated by the boiler to the water turbine, and the water turbine. Speed detection means for detecting the rotation speed of the water supply, a feedwater flow rate control means for outputting a speed set value based on the flow rate of feedwater supplied to the boiler, and a deviation between the speed set value and the speed detection value detected by the speed detection means. To perform the proportional / integral compensation calculation and output the vapor pressure control signal,
Steam pressure control means for opening the high pressure control valve after fully opening the low pressure control valve; servo drive means for inputting the steam pressure control signal to open and close the low pressure control valve and the high pressure control valve; When the load of the machine is cut off, a preliminary steam pressure control signal based on the header pressure of the boiler is given to the steam pressure control means to increase the integral output, and the opening of the high pressure control valve is set to an opening position based on the preliminary steam pressure control signal. And a reserve steam pressure control signal generating means. 5. A generator for driving a generator, comprising: a main steam turbine having a high-pressure turbine, a medium-pressure turbine, and a low-pressure turbine; a boiler for generating steam to be supplied to the main steam turbine; and water supply to the boiler. A feedwater turbine that drives a feedwater pump, a low-pressure control valve provided in a bleed supply pipe system that supplies low-pressure steam extracted from the main steam turbine to the feedwater turbine, and high-pressure steam generated by the boiler to the feedwater turbine. A high-pressure regulator provided in a main steam supply pipe system for supplying, a duplex speed detection means for detecting a rotation speed of the water supply turbine, and a speed set value determined by a water supply flow rate required by the boiler are output. And a deviation between the speed set value and the speed detection value detected by the speed detection means, and performs a proportional / integral compensation calculation to perform steam / water flow control. A steam pressure control means for outputting a pressure control signal and opening the high pressure control valve after fully opening the low pressure control valve; and inputting the steam pressure control signal to open and close the low pressure control valve and the high pressure control valve. A hydraulic servo and a preliminary steam pressure control signal based on the header pressure of the boiler when the load of the generator is cut off are supplied to the steam pressure control means to increase the integral output, and after the low pressure control valve is fully opened, the high pressure control valve is opened. And a function generating means for setting the opening degree to an opening position based on the preliminary steam pressure control signal.