JPS63685B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic feed water pump switching device, and more particularly to an automatic feed water pump switching device that is most suitable for use in a steam generator in a nuclear reactor or the like.

[Conventional technology]

A feed water pump for a steam generator (for example, a boiling water reactor) is composed of a plurality of pumps with different drive systems, such as turbine drive and motor drive. When the output of the steam generator is low, a motor-driven water pump (M-RFP) is mainly used.
During the output increase process, the turbine-driven water supply pump (T-
RFP).

Conventionally, this switching operation was performed manually by an operator. The turbine-driven water pump controls the water pump flow rate based on the turbine rotation speed.
When the rate of increase in the turbine rotational speed is increased, the flow rate increases rapidly and the water level in the steam generator rises. In boiling water reactors, fluctuations in water level are strictly limited due to core cooling requirements, and when the reactor water level exceeds a specified value, an interlock is activated that causes the main turbine to trip. In addition, there are interlocks for reactor scram and emergency core cooling system activation in response to water level drop. Therefore, the switching operation of the water supply pump has been performed carefully and over a long period of time by experienced operators.

In response to this, in recent years, devices have been proposed that automatically switch the water supply pump without manual intervention, such as the system shown in FIG. 1, for example.

Steam generated in the nuclear reactor 1 passes through a main steam pipe 2, is introduced into a turbine 3, drives a generator (not shown), and is then sent to a condenser 4 and returned to water.
The pressure of this condensate is increased by a low-pressure condensate pump 5 and a high-pressure condensate pump 6, and the pressure of this condensate is increased by a turbine-driven water supply pump (T
-RFP) 7 and motor-driven water pump (M-
RFP) 8 further increases the pressure, and water is supplied to the reactor 1 via a water supply pipe 10. Usually, a total of four water pumps are used: two turbine-driven water pumps and two motor-driven water pumps. When starting the turbine, the motor-driven water supply pump 8 is operated, and when the turbine reaches approximately 20% output, the turbine-driven water supply pump 7 is operated. Adder 1
1, the reactor water level is subtracted from the water level set point. This output is added to the main steam pressure in an adder 12 and becomes a control signal for the main controller 13. At the start of startup, the computer 14 controls the switch 15 to turn off and the switch 16 to turn on, so the main controller 13
Only the water supply regulating valve 9 is controlled by the water supply control valve 9. As described above, when the reactor output increases, the computer 14 turns on the switch 15 and turns off the switch 16. Therefore, the output of the main controller 13 is sent to a function generator 17 to generate a control pattern. The output of the function generator 17 is sent to a turbine controller 18 to control the amount of turbine steam for the feed water pump 7. Here, a so-called three-element water supply control system is shown that includes three elements: main steam flow rate, reactor water level, and feed water flow rate signal, but there is also a one-element control system that controls only the water level of the steam generator.

[Problem that the invention seeks to solve]

In the switching method shown in FIG.
The system switches between a motor-driven water pump and a turbine-driven water pump instead of manual operation.
The disadvantage is that the switching time is long.

In other words, in conventional switching control, if the speed setting of the turbine-driven feed water pump is increased manually or automatically after pressure equalization control is completed, the excess flow rate increases the reactor water level and generates a negative signal in the feed water control system. , reduce the flow rate of the motor-driven water pump. When the output signal of the water supply control system and the speed setting value of the turbine-driven water supply pump become equal, the turbine-driven water supply pump is automatically turned on by the water supply control signal, and the motor-driven water supply pump is separated from the water supply control system instead.
Therefore, manually or automatically throttle the water supply adjustment valve.
This time, the water supply flow rate will be reduced slightly to lower the reactor water level, causing the water supply control system to issue an increase signal. This signal increases the turbine-driven water pump speed,
Water pump switching progresses. In this way, since the feed water pump is switched using the reactor water level as an intermediary, switching control after pressure equalization control alone takes approximately
It took 20 minutes.

In addition, there is also a method of switching the water pump by having a low value priority circuit select the control output and switching signal of the 1, 3 element control system. In nuclear power plants, from a safety perspective, it is necessary to switch the feed water pumps while keeping the water supply control system alive at all times, so it is not possible to switch by applying operation signals to both the turbine drive and motor drive at the same time. That is, first, a signal to increase the speed of the turbine-driven water pump is applied to operate the turbine-driven water pump in parallel with the motor-driven water pump, and then the flow rate of the motor-driven water pump is reduced and switched, so as above, the switching time is long. There is a drawback.

Further, in this case, since a low value priority circuit is used, if the switching signal is lost, the water supply flow rate will decrease, leading to a decrease in the reactor water level, which is unfavorable from the standpoint of reliability.

An object of the present invention is to provide a water pump automatic switching device that can switch over in a short time with little water level fluctuation during switching.

[Means for solving problems]

In order to achieve the above object, the present invention provides a motor-driven water supply pump and a turbine-driven water supply pump for supplying condensate to a steam generator, and a flow rate supply request value on the steam generator side and a discharge of the motor-driven water supply pump. A motor-driven water feed pump control system that adjusts the amount of water supplied from the motor-driven water feed pump based on the flow rate, and a motor-driven water feed pump control system that adjusts the rotation speed of the turbine-driven water feed pump based on the flow rate request value on the steam generator side and the outlet flow rate of the turbine-driven water feed pump. In an automatic feedwater pump switching device that switches between both pumps according to the heat output of a steam generator consisting of a turbine-driven feedwater pump control system,
At the start of switching, a speed-up controller outputs a speed-up signal with a predetermined speed-up rate and a limited upper limit to the turbine-driven water supply control system to speed up the turbine-driven water supply pump to a predetermined rotation speed, and after speed-up control, the water supply pump A pressure equalizing controller that detects the differential pressure between the outlet header pressure and the turbine-driven water supply pump discharge pressure and outputs a signal with upper and lower limits to the turbine-driven water supply pump control system to bring the discharge pressure closer to the header pressure, and a pressure equalization controller. Later, an increase signal with a predetermined rate of change and a limited upper limit is output to the turbine-driven water supply pump control system to increase the amount of water supplied from the turbine-driven water pump, and at the same time,
An automatic water pump switching device is proposed that includes a switching control system that outputs a decrease signal corresponding to this increase signal to a motor-driven water pump control system to reduce the amount of water supplied from the motor-driven water pump.

The pressure equalization controller may also include a high value priority circuit that selects the high value of its own output signal and the rising signal from the switching controller to achieve so-called bumpless switching.

[Effect]

In the present invention, instead of the conventional switching system in which the water supply flow rate of the motor-driven water supply pump and the water supply flow rate of the turbine-driven water supply pump are made to correspond indirectly through the reactor water level, water is supplied by the turbine-driven water supply pump. Since both pumps are switched in direct correspondence between the increase in water supply and the decrease in water supply by the motor-driven water supply pump, water level fluctuations are kept to a minimum while reducing the time to approximately 3 minutes, approximately 1/6 or less of the conventional rate (see Figure 3 below). The process from increasing speed to switching can be completed within a few seconds.

〔Example〕

FIG. 2 is a block diagram showing an embodiment of the water supply pump automatic switching device according to the present invention. This is an example in which a boiling water reactor is used as the steam generator, and the configuration of the steam flow path and water supply system is the same as the system shown in FIG.

In the reactor water level control system, an adder 22 calculates the deviation between the reactor water level signal 20 and the water level setting signal 21, and a water level controller 23 performs proportional and integral calculations. Furthermore, the main steam flow rate signal 24 and the water level controller 23
The adder 25 adds the outputs of the flow rate and the flow rate required value through a compensator 26 having a lead/lag function.
This flow rate request value becomes a set value of a subloop control system that independently controls the flow rate of each pump. That is,
In the case of a turbine-driven feed water pump, the adder 28 calculates the deviation between this flow rate request value and the pump outlet flow rate (check valve flow rate) signal 27, and the flow rate controller 29 performs proportional/integral calculations. This controller output is provided to the turbine controller 30. The output of the turbine controller 30 is given as a signal to open and close a steam control valve 32 that controls the flow rate of low-pressure steam extracted from the main turbine 3, thereby controlling the rotation speed of the feed water pump driving turbine 31. On the other hand, in the case of a turbine-driven water supply pump, the output of the flow rate controller 33 directly controls the water supply regulating valve 9 .

The feed water pump is usually provided with feed water recirculation valves 34 and 35 for the purpose of preventing the pump from overheating due to shut-off operation, and ensures that the water pump suction flow rate is at least a certain amount. These valves 34, 35 take in pump suction flow signals 36, 37 and provide a recirculation flow controller 3 with on/off or continuous control functions.
8,39.

Note that the flow rate control systems and pump configurations of the turbine-driven feed water pump B and the motor-driven feed water pump B (not shown) are the same as those of the respective pumps A in FIG. Loads the output flow rate request value.

Turbine-driven water pumps have a rated water flow rate of 55
%, the motor-driven water pump has a capacity of 27.5%, and in the range of 50-100% reactor power, two turbine-driven water pumps are used, and two motor-driven water pumps are on standby as backup. .

On the other hand, during the reactor startup process, a motor-driven water pump is used because turbine-driving steam is not available. That is, the reactor power is operated as follows: 0-20%: 1 M-RFP 20-50%: 1 T-RFP 50-100%: 2 T-RFPs.

Therefore, at approximately 20% reactor output, it is necessary to switch from a motor-driven water feed pump to a turbine-driven water pump, and at approximately 50% output, it is necessary to start up and join the second turbine-driven water pump. is necessary.

The configuration that performs this switching is the control unit 100 shown in FIG. ) Switching control can be divided into three types.

Here, each control stage is defined as follows.

(1) Speed-up control...Increasing the speed of the turbine-driven water supply pump to a predetermined rotational speed at a predetermined speed-up rate. The predetermined rotation speed is the rotation speed (approximately 1/2 of the rated speed) that is below the rated speed and provides sufficient pump discharge pressure to prevent water from being supplied to the reactor through the pump outlet check valve.

(2) Pressure equalization control: After the end of speed increase control, bring the pump discharge pressure closer to the pump discharge header pressure. The process ends when the differential pressure between the two becomes zero.

(3) Switching control: Switching the share of the pump flow rate that contributes to the reactor feed water flow rate from one pump to another.

Next, each control stage will be explained in detail.

(1) Speed-up control The output of the speed-up control setting device 101 is output from the switch 102.
It is applied to an integrator 103 via S ₁ and integrated.
This integral output is limited to within a predetermined integral value by a limiter 104, and is output to a speed converter 40 provided in the turbine controller 30. The output of the limiter 104 becomes the speed-up signal _C1 . The turbine controller 30 is
The steam supplied to the turbine 31 from the turbine-driven water supply pump 7 is adjusted to increase the speed of the turbine-driven water supply pump 7 to a predetermined rotational speed at a predetermined rate of increase.

(2) Pressure equalization control After the speed increase control is completed, the differential pressure between the water supply pump outlet header pressure and the discharge pressure of the turbine-driven water supply pump 7 is detected by the differential pressure detector 105, and the switch 106 is activated.
S ₂ , limiter switch 107, signal converter 10
8. Input to high value priority circuit 110 via compensator 109. The output C' ₂ of the high value priority circuit 110 is added to the bias 111 in an adder 122, and (T-
RFP)/(M-RFP) switching signal _C2 , which is applied to the adder 28 of the turbine-driven water pump flow control system.

The signal from the differential pressure detector 105 is positive when the flow rate passing through the check valve 41 is 0, but becomes negative when a flow rate occurs, so it is used to cut the negative value and continue pressure equalization control. It will be done. The upper and lower limits of the limiter 107 are both set to positive values.

That is, since the output signal of the differential pressure detector 105 is a value obtained by subtracting the pump discharge pressure from the discharge header pressure, the output signal approaches zero from a positive value in the first half of the pressure equalization control. Open the pump discharge check valve 14,
When a flow rate passes through this point, the turbine pump discharge pressure becomes higher than the discharge header pressure, and the differential pressure changes to a negative value. Limitatsuta 1
The reason why the lower limit value of 07 is set to a positive value is that if it becomes a negative value, the speed of the turbine-driven water supply pump will decrease and the operation will be the opposite of pressure equalization, and if the differential pressure approaches 0, switching will occur. This is to avoid these inconveniences, since the signal C' ₂ also approaches 0, and the progress of pressure equalization control of the turbine-driven water pump becomes stagnant, making it impossible to achieve rapid operation, which is one of the objectives of the present invention. .
Note that the signal converter 108 determines a gain for converting a pressure signal into a control system signal.

It is assumed that the compensator 109 has the following transfer function.

G _R = K ₂ /1 + T _2S ...(1) However, K ₂ = T _f /K _f T ₂ = T _f K _f =; Proportional gain of flow rate controller 29 (%/%) T _f =; 〃 Integral Time (seconds) s: Laplace operator Here, the compensator 109 has a function such that the output of the flow rate controller 29 has a constant rate of change no matter what the control constant of the flow rate controller 29 is. It's set.

That is, since the transfer function of the flow rate controller 29 is G _c =K _f (1+1/T _f s) (2), the composite transfer function G _T of the compensator 109 and the flow rate controller 29 is G _T =G _R・G _c =T _f /K _f /1+T _f s ・K _f (1+1/T _f s) = 1/s...(3) Therefore, it is an integral function with a gain of 1 regardless of the control constant. Can be done.

(3) Switching control The signal of the switching change rate setter 112 is
13S ₃ , an integrator 114, and a limiter 115, it becomes a switching signal C ₃ and becomes one input of the high value priority circuit 110, while being added as a negative value to the input adder 116 of the motor-driven water supply pump flow rate control system,
Switching between both pumps is performed.

The conditions for starting automatic water pump switching are as follows:
It is assumed that one motor-driven water supply pump 8 is operating at a water supply flow rate of 20%, and preparations for starting the turbine 31 of the turbine-driven water supply pump 7 are completed. The water supply control system includes a water level controller 23, a flow rate controller 29,
All 33 are automatic, switch S ₁ ,
Both S ₂ and S ₃ are open. The input adder 28 of the turbine-driven water supply pump flow rate controller 29 has the output (water supply request value) of 20% of the lead/lag compensator 26.
Since the flow rate signal 27 is 0, -20% is applied to the bias 111, the output of the adder 28 is 0, and the output of the flow rate controller 29 is also 0. On the other hand, the adder 116 on the motor-driven water supply pump side has a signal of 20% from the advance/lag compensator 26, the flow rate signal 42 is 20%, and the water supply regulating valve 9 is controlled to a certain opening degree and is in a stable state. be.

The operating characteristics of each part (reactor water level, control signal, flow rate) of the embodiment shown in Fig. 2 are shown in Fig. 3.

Referring to FIG. 3, the operation of the embodiment shown in FIG. 2 will be explained in more detail.

Note that C ₂ is not shown in Figure 3 because C ₂ is
Since it is a value obtained by adding a bias to C' ₂ by the adder 122, it is a signal obtained by shifting C' ₂ , and the waveform itself is the same as C' ₂ , so this is to avoid complexity.

(1) Speed-up control First, when the switch _102S1 is turned on manually or automatically, the speed-up signal _C1 increases at a constant rate and rises to the upper limit value of the limiter 104, and pressure equalization control is performed. As a result, the rotation speed of the water supply pump driving turbine 31 increases and becomes a constant rotation speed.
This speed is on the order of 60% of rated, and at this speed the pump discharge pressure is less than the outlet header pressure and all of the pump discharge flow is flowing through the recirculation valve 34. The turbine control system 30 is configured such that when the output of the speed converter 40 reaches an upper limit value of a high speed limiter (not shown), it can be controlled by the input signal of the flow rate controller 29.
Therefore, the speed increase signal _C1 may be set to a value that is slightly higher than the upper limit value of the high speed limiter, and the value of the speed increase rate setter 101 may be set to a desired turbine speed increase rate.

(2) Pressure equalization control When the turbine speed has settled to approximately 60%, turn on switch _106S2 manually or turn on. switch 1
When 06 is turned on, the discharge pressure of the turbine-driven water pump is at a considerably lower level than the header pressure, so the differential pressure detector 105 outputs a differential pressure signal.
It instantly rises above the upper limit value of limiter 107.
The output of the signal converter 108 increases stepwise as shown in C ₁₀₈ , but the transfer function of the compensator 109 is
As shown in the equation, since it is a first-order delay, the actual rise of the signal is slow, resulting in a characteristic similar to C' ₂ .
This signal _C'2 is the output _C''2 of the high value priority circuit 110. That is, the output signal _C''2 of the limiter 115 is selected as the high value signal. The feed water pump driving turbine 31 is gradually increased in speed by the signal _C'2 , and the discharge pressure of the turbine driven water pump increases, so the differential pressure signal that is the output of the differential pressure detector 105 decreases.
The C′ ₂ signal also decreases.

Even if this differential pressure becomes small, it is necessary to increase the speed to a certain degree, and the lower limit value of the limiter 107 described above works effectively. In addition, increasing the rate of increase when the differential pressure at the discharge part of the turbine-driven water pump is large and decreasing the rate of increase when the differential pressure is small is due to the check valve that occurs upon completion of pressure equalization. It is very effective for suppressing the increase in the flow rate and achieving pressure equalization control in a short time.

(3) Switching control At the point where the differential pressure at the discharge part of the turbine-driven water pump becomes 0, the check valve 41 opens and a flow rate begins to occur. At this point, it is considered that the pressure equalization control is completed, and the switch _S3 is turned on manually or automatically when this differential pressure becomes 0 or the check valve flow rate occurs, or when the check valve opens. Switching signal C ₃ is switching change rate setter 1
This is a signal that increases at a constant rate until it reaches the upper limit value of the limiter 115 by integrating the 12 signals.

On the other hand, since the output of the adder 116 becomes negative and the _-C3 signal is applied to the motor-driven water supply pump flow rate control system, the motor-driven water supply pump flow rate immediately begins to decrease. On the other hand, for the turbine-driven feedwater pump flow rate control system, from the time t ₁ when the C ₃ signal becomes larger than the output signal C″ ₂ of the compensator 109
C ₃ is selected, and C′ ₂ becomes a ramp-like rising signal. During the time from when the switch _S3 closes until _t1 , the flow rate of the check valve of the turbine-driven water supply pump begins to flow due to the acceleration of the pressure equalization control, so the water supply flow rate increases slightly. In consideration of the increase in the flow rate of the turbine-driven water pump due to this acceleration, the high value priority circuit 110 is useful for switching between pressure equalization control and switching control continuously and with little flow rate fluctuation, resulting in so-called bumpless switching. After t ₁ , the switching signal as shown in the middle row of FIG. 3 causes the motor-driven water pump flow rate to decrease and the turbine-driven water feed pump flow rate to increase, with almost no fluctuation in the water supply flow rate, and the switching is executed. When the flow rate of the motor-driven water supply pump reaches 0, the motor and disconnector (not shown) of the motor-driven water supply pump are turned off, and the switching is completed.

As a result of actual measurements of fluctuations in the reactor water level using such a switching means, it was confirmed that fluctuations in the reactor water level could be kept within ±1.5 cm.

According to the embodiment shown in FIG. 2, the following effects can be obtained.

Water supply pumps can be switched while keeping all flow control systems that are subject to switching.

The high value priority circuit allows continuous transition from pressure equalization control to switching control while minimizing flow rate fluctuations.

Since the flow rate of both pumps can be changed simultaneously while keeping the water supply control system alive, switching can be done smoothly in a short period of time.

Since it uses a set point change method, even if the switching signal is lost, the control system remains active, and water supply fluctuations and water level fluctuations can be kept to a minimum.

In addition, in the above embodiment, speed increase control, pressure equalization control,
Switching control boundaries (so-called breakpoints)
Although it is assumed that the switches S ₁ to _{S 3} are switched manually or automatically, it is clear that the above effects can be obtained in either case.

FIG. 4 is a block diagram of the turbine-driven water supply pumps in parallel operation according to the present invention.

In this example, the reactor output is approximately 50%, and the second turbine-driven feed water pump is started and added.The same reference numerals in the diagram refer to the same parts as in Figure 2. There is. The motor-driven water supply pump control system in FIG. 2 is replaced with a flow control system for the turbine-driven water supply pump A in operation, and the configuration of the switching control is the same as that in FIG. 2. That is, for the turbine-driven water pump B to be started, the second
This can be achieved by applying the same speed increase, pressure equalization, and switching signals as in the case shown in the figure. In this case, the switching is completed until the turbine-driven feedwater pumps each share 25% of the flow rate.

FIG. 5 is a block diagram showing switching from parallel operation to individual operation according to the present invention.

In this example, the number of turbine-driven water pumps changed from two to one.
This is a case in which the reactor output is reduced to 50% when the output is lowered. 4 using only the switching control system shown in Figure 2.
It is sufficient to control the water supply pump system with the same configuration as shown in the figure. That is, a positive switching signal is applied to the flow rate control system of the water supply pump turbine-driven water pump A, which continues to operate, and a negative switching signal is applied to the flow rate control system of the water supply pump B, which is to be stopped. If the adders 28a and 28b are wired together, the desired switching can be performed by turning on the switch _S3 . When the check valve flow rate of the stop pump becomes 0, the turbine-driven water supply pump is tripped. This pump trip is the sudden closing of a steam stop valve (not shown) of the drive turbine.

FIG. 6 is a block diagram illustrating switching from a turbine-driven water pump to a motor-driven water pump according to the present invention.

In this example, the turbine-driven feedwater pump is switched to the motor-driven feedwater pump when the reactor output drops to 20%. To start the motor-driven water supply pump, first apply a bias 117 to fully close the water supply adjustment valve 9 so that the adder 118 outputs -20%. In this state, the motor and disconnector of the motor-driven water supply pump (not shown) is turned on.
When the rotational speed of the motor-driven water supply pump reaches the rated value, switch _113S3 is turned on. A negative switching signal is applied to the turbine-driven water pump and a positive switching signal is applied to the motor-driven water pump. That is, a negative switching signal is sent to the adder 28,
A positive switching signal is applied to adder 116. The switching progresses as the switching signal changes, and the turbine-driven water pump may be tripped when the switch is completely switched to the motor-driven water pump.

〔Effect of the invention〕

According to the present invention, since the increased amount of water supplied by the turbine-driven water supply pump and the decreased amount of water supplied by the motor-driven water pump are directly matched and switched between the two pumps, it is possible to switch between the two pumps in a short time while minimizing fluctuations in the amount of steam generation and water level. A water pump automatic switching device capable of automatically switching a water pump is obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional water pump switching system, Fig. 2 is a block diagram showing an embodiment of an automatic water pump switching device according to the present invention, and Fig. 3 is a block diagram showing a conventional water pump switching system.
Figure 4 is a block diagram showing the configuration of parallel operation of turbine-driven water pumps according to the present invention, and Figure 5 is a block diagram showing the configuration of switching from parallel operation to independent operation according to the present invention. , FIG. 6 is a block diagram showing a configuration for switching from a turbine-driven water supply pump to a motor-driven water supply pump according to the present invention. 1... Nuclear reactor, 3... Turbine, 4... Condenser, 7... Turbine driven water pump (T-
RFP), 8...Motor-driven water pump (M-
RFP), 10... Water supply pipe, 22, 25, 28, 1
22,116,118...Adder, 23...Water level controller, 26,109...Compensator, 29,33...
...Flow rate controller, 30...Turbine controller, 31...
...Turbine, 32...Steam control valve, 34, 35...
... Water supply recirculation flow rate adjustment valve, 38, 39 ... Recirculation flow rate controller, 40 ... Speed converter, 100 ... Control unit, 101 ... Speed increase rate setting device, 102, 10
6,113...Switch, 103,114...Integrator, 104,115...Limiter, 105...
Differential pressure detector, 108...Signal converter, 110...
High value priority circuit, 112...Switching change rate setting device.

Claims (1)

[Claims] 1. A motor-driven water supply pump and a turbine-driven water supply pump for supplying condensate to a steam generator;
A motor-driven water feed pump control system that adjusts the amount of water supplied from the motor-driven water pump based on a flow rate supply request value on the steam generator side and a discharge flow rate of the motor-driven water feed pump; and a flow rate request value on the steam generator side. and a turbine-driven water pump control system that adjusts the rotation speed of the turbine-driven water pump based on the outlet flow rate of the turbine-driven water pump, and an automatic water pump switching device that switches between the two pumps according to the thermal output of a steam generator. , a speed-up controller that outputs a speed-up signal with a predetermined speed-up rate and a limited upper limit to the turbine-driven water supply control system to speed up the turbine-driven water supply pump to a predetermined rotational speed at the start of switching; and after the speed-up control; , pressure equalization control that detects the differential pressure between the water supply pump outlet header pressure and the turbine-driven water supply pump discharge pressure and outputs a signal with upper and lower limits to the turbine-driven water supply pump control system to bring the discharge pressure closer to the header pressure; and, after the pressure equalization control, outputs a rising signal having a predetermined rate of change and a limited upper limit to the turbine-driven water feed pump control system to increase the amount of water supplied from the turbine-driven water pump, and at the same time, increases the amount of water supplied from the turbine-driven water pump, and at the same time corresponds to the rising signal. and a switching controller that outputs a reduction signal to the motor-driven water pump control system to reduce the amount of water supplied from the motor-driven water pump. 2. The water pump automatic according to claim 1, wherein the pressure equalization controller includes a high value priority circuit that selects a high value of the output signal of the equalization controller and the high value of the increase signal from the switching controller. Switching device.