JPS61180811A - Control system of feedwater pump for power station - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a feed water pump control system for a power plant, and particularly to a steam generator that generates steam that is a driving source for a main steam turbine that drives a generator. The present invention relates to a water supply pump control system for a power plant that is suitable for efficiently controlling a water supply pump that supplies water according to the operating state of the power plant.

[Background of the invention]

The boiler feed water pump in thermal power generation equipment or the reactor feed water pump in nuclear power generation equipment is supplied with steam, which is the driving source for the main steam turbine that drives the generator, and is driven by a feed water pump turbine that operates according to the steam pressure. It is often done.

A system for operating a water supply pump using this water supply pump turbine, for example, detects the rotational speed of the water supply pump turbine, and sets the rotational speed of the water supply pump turbine in correspondence with this detected value and the required value of the water supply flow rate for the steam generator. A control section that compares the set value of An apparatus has been proposed that includes a variable steam pressure adjustment section and is configured to supply water to a steam generator at a flow rate corresponding to the operation of a water supply pump.

This system can obtain a desired feedwater flow rate by maintaining the rotational speed of the feedwater pump turbine at a set value.

Furthermore, in this system, the feedwater pump turbine is configured to operate the feedwater pump according to the steam pressure, so that steam from two systems, the extraction supply system and the main steam supply system, is supplied to the feedwater pump turbine, and The opening degrees of the regulating valves assigned to these two systems are adjusted in accordance with the required value of the water supply flow rate to maintain the rotational speed of the water supply pump turbine at a set value. Conventionally, as a control method for regulating valves installed in steam systems with two different amounts of energy, one proportional-integral calculator was used for each of the extraction supply system and the main steam supply system, and the speed of the feedwater pump turbine and The feed water pump can be stabilized regardless of steam conditions by inputting the deviation signal between the speed setting value corresponding to the required value of the feed water flow rate to each proportional-integral calculator, and switching and using the calculated signal. There are known methods to control this. (Unexamined Japanese Patent Publication No. 59-2
Publication No. 9704. ) By the way, at a power plant, when an accident occurs in the power transmission line system, etc., the power generation unit is disconnected from the system and the power generation output is instantly reduced to the power of the auxiliary equipment in the station, which is equivalent to a few percent of normal operation. Back (PCB) operation is performed. During PCB operation or normal start-up operation, the amount of extracted air from the main steam turbine decreases.

Feedwater pump turbines driven by low-pressure bleed air need to be driven by main steam from the main steam supply system due to a reduction in the amount of bleed air.

Otherwise, the rotational speed of the water supply pump turbine will decrease and the desired water supply flow rate cannot be obtained.

The above-mentioned system has two types of proportional-integral calculators, and uses a low-pressure regulating valve for steam control in the bleed air supply system and a high-pressure regulating valve for steam control in the main steam supply system. The set values in the proportional-integral calculator are fixed, and the characteristics of the amount of steam with respect to the opening degree of the control valve change depending on the operating conditions of the power plant, making it impossible to set the settings to adapt to any operating condition.

In other words, the amount of change in the amount of steam flowing into the water supply pump turbine with respect to the opening degree of the control valve suddenly changed, which could cause hunting in the water supply system.

In particular, when two feed water pump turbines are operated by steam drive in the start-up operation state, the main steam of the main steam supply system is used at a high rate, and the steam characteristics with respect to the control valve are different from when one turbine is operated. This is because the extracted air is distributed and used between the two water supply pump turbines, which reduces the amount of extracted air per unit.

For these reasons, it has been difficult for the water supply flow rate by the water supply pump turbine to immediately respond to the required value.

[Purpose of the invention]

An object of the present invention is to provide a water supply pump control system for a power plant that can control the water supply flow rate in response to a required value of the water supply flow rate.

[Summary of the invention]

In the present invention, steam that is a driving source for a main steam turbine that drives a generator is supplied from a steam generator, and the rotational speed of a water supply pump turbine that operates a water supply pump is detected according to the steam pressure, and this detected value is and a control unit that compares the feedwater pump turbine rotational speed corresponding to the requested value of the feedwater flow rate for the steam generator with a teno set value to determine the deviation, and outputs a steam pressure control signal to suppress this deviation. ,
Feed water pump A water feed pump for a power plant that is equipped with a steam pressure adjustment unit that changes the pressure of steam supplied to a turbine in accordance with a steam pressure control signal, and supplies water to a steam generator at a flow rate corresponding to the operation of the feed water pump. In a control system, the non-linear relationship between the amount of steam and the opening of the main body control valve is determined by the control valve control signal when the power plant is started up and when the power plant's power generation output suddenly drops, when the driving steam source to the feedwater pump turbine is switched. [Embodiments of the Invention] Hereinafter, the present invention will be described in detail based on the drawings.

As shown in FIG. 1, the system of this embodiment detects the rotational speed of the water supply port/bottom pin 12 that operates the water supply pump 10 according to the steam pressure supplied from the steam generator (not shown). Then, this detected value is compared with the set value for the feed water pump turbine rotation speed that corresponds to the required value of the feed water flow rate for the steam generator to find the deviation, and a steam pressure control signal is output to suppress this deviation. and the pressure of the steam supplied to the feed water pump turbine 12,
It is equipped with a steam pressure adjustment section 2 that changes the steam pressure according to a steam pressure control signal, and can supply water to the steam generator at a flow rate corresponding to the operation of the water supply pump 10.

That is, the control unit 1 has speed detectors 18 and 20, and detects the rotation speed of the gear 220 connected to the drive shaft of the water pump 10 and the water pump turbine 12, and uses the detected value. is configured to be detected as a rotational speed signal of the water supply pump turbine 12. Speed detector 1
The detection signals according to 8.20 are respectively supplied to a true value selector 28 via speed signal converters 24 and 26. The true value selector 28 selects the true value from among the two rotational speed signals. That is, if the difference between the three signals is within the tolerance value, the higher value is determined to be the true value, and if the difference is greater than or equal to the tolerance value, the one with the smaller rate of change is determined to be the true value.
, is supplied to the water supply control device 32.

The feed water control device 32 converts the signal from the true value selector 28 into a set value for the feed water pump turbine rotation speed that is associated with the requested value of the feed water flow rate for the steam generator, and converts this signal into a set value for the feed water pump turbine rotation speed. supply to. Deviation calculator 3
0 compares the output signal from the true value selector 28 and the water supply control device 32, calculates the deviation, and calculates the deviation from the output signal from the proportional integral calculator 34.
supply to. The proportional-integral calculator 34 performs a calculation to suppress the deviation from the deviation calculator 30, and supplies a steam pressure control signal to the steam pressure adjustment section 2 in accordance with this calculated value.

The steam pressure adjustment section 2 includes an amplifier 38 and an electro-hydraulic converter 40.
, hydraulic servo 42, link mechanism 44, low pressure regulating valve 46,
It is composed of a high pressure regulating valve 48. When the vapor pressure control signal is supplied to amplifier 38, this signal is amplified by amplifier 38 and then supplied to electro-hydraulic converter 40 for conversion to a hydraulic servo level. Then, the hydraulic servo 42
By operating the link mechanism 44 according to the hydraulic servo level, the opening degrees of the low pressure regulating valve 46 and the high pressure regulating valve 48 are controlled, and the steam supplied to the feedwater pump turbine 12 from the extraction supply system 50 and the main steam supply system 52 is controlled. pressure can be changed.

Since the high pressure regulating valve 48 is configured to open after the low pressure regulating valve 46 is fully opened, the amount of steam supplied to the feed water pump turbine 12 is determined according to the hydraulic servo level as shown in FIG. The relationship will be such that

That is, when the hydraulic servo level is in the range of 0% to a%, the pressure is low.
During the arrival of the valve 46, it becomes active between 0"l and 100V, and the amount of vapor of the color changes according to the characteristics.Also,
When the hydraulic servo level exceeds a%, the high pressure regulating valve 48 starts to open, and when the hydraulic servo level is in the range of 8% to 100%, the opening degree of the high pressure regulating valve 48 becomes 0% to 100%, and the steam amount increases. Varies according to characteristic B. When the hydraulic servo level is 100%, the amount of steam equal to the amount of steam C10 is supplied to the water supply pump turbine 12. In addition, this characteristic will be a low pressure characteristic like characteristic E at the time of start-up operation or PCB operation. It is characterized in that it immediately responds to the required value of the water supply flow rate when the operation shifts to the PCB operation.

A function generator 63 that can change the gain of the hydraulic pressure level with respect to the steam pressure control signal is added to the steam pressure adjustment section 2.

Furthermore, the function characteristics of this function generator 63 are determined by the bleed air supply system 50.
The low-pressure steam pressure 61 from the low-pressure steam pressure detector 60 installed in the 1. Intervention 2 That is, input the low pressure steam pressure 61 to the function generator 63, change the characteristics A/, B/, c/ and generate the start signal 64.
, FCB signal 65 is input, optimal characteristics can be set. As a result, the amount of change in the steam pressure control signal from the proportional-integral calculator 34 can be adjusted to maintain a constant amount of change in the amount of steam flowing into the feedwater pump turbine relative to the hydraulic servo level.

The characteristics of the function generator 63 will be explained using FIGS. 3(a) to 3(b). Figure (a) is a rewrite of the characteristics E and B in Figure 2 and represents the total amount of steam flowing into the feedwater pump turbine.Characteristics E, B and characteristics E/, B / indicates that there is a state. Furthermore, characteristics B and B' indicate that the amount of change in steam amount relative to the amount of change in the hydraulic servo level is larger than that in characteristics E and E'. This is a property of the body, so (
b) A linear relationship is established by adding the functional characteristics shown in the figure. In the past, the amount of change in the hydraulic servo level with respect to the steam pressure control signal was constant, but the characteristics A/, B/, c in the range of the hydraulic servo level from ka% to 100%.
/ By lowering the gain, the amount of change in the hydraulic servo level is lowered, and the amount of change in steam is reduced to a level between a% and 100% of the hydraulic servo level.
Make sure it doesn't suddenly grow large. Characteristics A/ , B/ ,
C/ is adjusted and set by the low pressure steam pressure 61, and the function generator 63 is made to have this characteristic.

Due to this, especially during PCB operation and start-up operation,
When the two water supply pump turbines are started up, the amount of change in the amount of steam flowing into the water supply cylinder/butter bin with respect to the opening degree of the regulating valve (hydraulic servo level phase, etc.) changes suddenly, and the water supply flow rate can be ensured.

〔Effect of the invention〕

According to the present invention, even when the driving steam source for the feedwater pump turbine is switched from extraction air to main steam during start-up operation of a power plant and when the power generation output of the power plant suddenly drops, the steam for the main body control valve opening is By adding a function generator for adjusting the regulating valve control signal, the non-linear relationship between the amounts can be made linear, and the water supply flow rate can be controlled in immediate response to the requested value of the water supply flow rate.

[Brief explanation of drawings]

Figure 1 is a system configuration diagram of an embodiment of the present invention, Figure 2 is a diagram of the relationship between hydraulic servo level and steam amount, and Figure 3 (a).
, (b) is a diagram showing the relationship among the steam pressure control signal, the hydraulic servo level, and the steam flowing into the water supply pump turbine. 12...Water supply pump turbine, 46...Low pressure regulator valve, light 3 diagram procedure amendment c method)

Claims (1)

[Claims] 1. Steam, which serves as a driving source for a main steam turbine that drives a generator, is supplied from a steam generator, and the rotational speed of a water pump turbine that operates a water pump is detected in accordance with the steam pressure. , comparing this detected value with a set value for the rotational speed of the water supply pump turbine that is associated with the requested value of the water supply flow rate for the steam generator, and determining a deviation therebetween;
a control unit that outputs a steam pressure control signal to suppress this deviation; and a control unit that controls the pressure of steam supplied to the feed water pump turbine.
A water supply pump control system for a power plant that supplies water to the steam generator at a flow rate according to the operation of the water supply pump, the system comprising: a steam pressure adjustment unit that changes the pressure according to the steam pressure control signal; , and a function generator for adjusting a moderation valve control signal to determine the nonlinear relationship of the steam amount to the main body moderation valve opening in switching the drive steam source to the feed water pump turbine when the power generation output of the power plant suddenly drops. A power plant water pump control system characterized by a linear relationship by adding .