JPH081122B2 - Water supply control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention is directed to a steam turbine that drives an oil pump, a water supply pump, and the like by a steam turbine, and uses the pressure oil and cooling water generated by these pumps. The present invention also relates to a water supply control device in a plant for cooling a steam source.

(Prior Art) Some steam turbine plants do not have a power source for turbine control or lubrication, but drive the oil pump by the turbine itself and supply oil for turbine control and lubrication. . As a pump system driven by this type of turbine, there is a reactor isolation cooling system as one of backup reactor auxiliary systems for emergency in a nuclear power plant.

When the reactor is isolated from the turbine condenser, this system replenishes cooling water from the condensate storage tank to the reactor to maintain the reactor water level and cool the reactor core. It is equipment and has a system configuration as shown in FIG.

In FIG. 3, reference numeral 1 indicates a nuclear reactor, and the nuclear reactor 1 is stored in a containment vessel 3 having a pressure suppression pool 2 at the bottom. The steam generated in the nuclear reactor 1 branches from the main steam line 4, is introduced into a turbine 9 via a steam line 8 having a motor-operated valve 5, a steam stop valve 6 and a steam control valve 7, drives it, and exhausts it. Is returned to the pressure suppression pool 2 via the exhaust line 10. Part of the steam in the main steam line 4 is returned to the pressure suppression pool 2 via the relief valve 11 in the containment vessel 3. Water supply to the reactor 1 is performed through a water supply line 12. A turbine shaft 13 of the turbine 9 is directly connected to a water supply pump 16 for supplying cooling water from the condensate storage tank 15 to the reactor 1 and an oil pump 17 for supplying lubricating oil to a turbine control device (not shown). .

In an emergency, such as when the water supply to the reactor is stopped, the reactor 1 is isolated and the water level in the reactor is lowered. Then, the motor-operated valve 5 starts to open, main steam flows through the steam stop valve 6 and the steam control valve 7 that are already open, and the turbine 9 is started. As a result, the water supply pump 16 is driven and cooling water is supplied from the condensate storage tank 15 to the reactor 1 to cool the reactor core. Here, the feed water pump 16 must supply a predetermined amount of cooling water to the nuclear reactor 1, and the turbine 9 must be rapidly started when it receives a start signal and must enter stable operation.

FIG. 4 shows a control device for the turbine 9. When a start command is issued and the motor-operated valve 5 starts to open, the main steam flows into the turbine 9 via the steam stop valve 6 and the steam control valve 7, which are already in the fully open state, and the turbine 9 is started. At the same time when the turbine 9 is started, the oil pump 17 directly connected is driven. When the speed is increased above a predetermined rotation speed, the pressure of the control oil 20 fed from the oil pump 17 is established, whereby pressure oil is sent to the electro-oil converter 21 and the oil cylinder 22, and the steam control valve 7 Is controlled. On the other hand, in order to control the discharge flow rate of the water supply pump 16 at a constant level, for example, a differential pressure transmitter type flow rate detector 23 is provided on the discharge side of the water supply pump 16.

During normal operation, the flow rate signal 23a from the flow rate detector 23
And the set flow rate signal 25a output from the flow rate setter 25 are guided to the deviation calculator 26, from which the flow rate deviation signal 26a representing the difference between the set flow rate and the actual flow rate is sent to the proportional calculator 27 and the integral calculator 28. Sent. These signals are added by the addition calculator 29, and the target speed signal 2 for making the flow rate deviation signal 26a zero.
9a is formed and sent to the speed control calculator 32 via the target speed setting calculator 31 as the set speed signal 31a. The speed control calculator 32 includes a speed detection gear attached to the turbine shaft 14.
33 and an electromagnetic pickup 34 arranged opposite to this
The actual speed signal 35a (representing the actual speed) obtained by the speed calculator 35 based on the output pulse of the speed detector consisting of is also introduced as a feedback signal of the speed control minor loop, where the deviation of both input signals, namely, A speed control signal 32a for reducing the deviation between the target speed and the actual speed to zero is formed and sent to the electro-oil converter 21. As a result, the steam control valve 7 is controlled to open and close. Further, a ramp signal generator 38 is provided for keeping the speed increasing rate constant when the turbine 9 is started. This is a start signal input at the beginning of opening of the motor-operated valve 5 by a limit switch provided in the motor-operated valve 5. Start with signal 39a.

When the turbine 9 is started, a ramp signal 38a that increases with a predetermined inclination with time is sent to the calculator 41. Similarly, the idle signal 42a from the idle signal calculator 42 which is activated by the activation signal 39a is also input to the calculator 41. The idle signal 42a is for giving the speed value of the ramp signal 38a at time zero (immediately after the start of activation), that is, the idle speed value. A ramp signal 41a is generated and sent to the target speed signal calculator 31. The target speed signal calculator 31 is
Of the target ramp signal 41a and the target speed signal 29a, a signal having a low value is always selected to form the target speed signal.

As shown in FIG. 5, assuming that a start command is issued at time t ₀ when the time becomes zero, the turbine 9 is started at time t ₁ with a slight delay as the motor-operated valve 5 is opened, and the speed thereof is increased. Rises rapidly according to the velocity curve C ₁ . But,
After that, the steam control valve 7 is controlled via the speed control calculator 32 by the target ramp signal 41a for increasing the idle speed n1 defined by the idle signal 42a according to the acceleration defined by the ramp signal 38a. It gradually rises according to the target ramp characteristic line C ₂ corresponding to the target ramp signal 41a.

On the other hand, as the flow rate of the water supply pump 16 gradually increases from zero, the flow rate deviation signal 26a corresponds to the set flow rate signal 25a.
Although it gradually decreases from the 100% value, the target speed signal 29a
, The integrated output of the flow rate deviation signal 26a is added, so that it temporarily overshoots after startup. After that, since the flow rate is larger than the set flow rate signal 25a, the flow rate deviation signal 26a becomes negative, the output of the integrator 28 decreases, and stable control is performed when the flow rate returns to a predetermined flow rate.

The line and the speed curve C ₁ of the target speed signal 29a obtained from the flow control system intersect at a point P at the time point t _2. After the point P, the turbine operation is continued according to the target speed setting apart from the ramp characteristic.

In the above apparatus, the load of the water supply pump 16 varies depending on the pressure inside the reactor 1, so that the water supply pump capable of flowing a predetermined flow rate.
The 16 rpm will vary with reactor pressure.

(Problems to be Solved by the Invention) Here, the problem is that the turbine 9 outputs the target ramp signal.
The flow rate deviation signal 26a is 100% at the time of starting, although it is started according to 41a, and after the water supply flow rate starts to output, the control shifts to control by the target speed signal 29a obtained from the flow rate deviation signal 26a.
Therefore, the output of the integrator 28 has a value almost close to the upper limit, and the rotation speed increases until the flow rate exceeds the predetermined flow rate and the integrated output is returned. Therefore, the turbine 9 is accelerated to a speed equal to or higher than the specified rotation speed, which causes problems such as overspeed trip and unstable flow rate control thereafter.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a water supply control device that shortens the time from the startup of a self-supporting turbine to a stable operation and enables stable water supply control. It is a thing.

[Structure of Invention]

(Means for Solving Problems) In order to achieve the above object, the present invention provides a steam turbine driven by steam supplied from a steam source through a steam control valve, and driven by the steam turbine, An oil pump that supplies control oil to the steam control valve and a water supply pump that supplies cooling water to the steam source, and the steam turbine according to a ramp function so that the water supply pump flow rate becomes a predetermined flow rate based on a start command. In the water supply controller including a speed controller for speed control, and a flow rate controller for comparing the discharge flow rate of the water supply pump with a set flow rate to control the steam turbine so that the pump flow rate becomes a predetermined flow rate, A pressure detector for detecting the steam pressure of, a target speed setting device for setting a target speed of the steam turbine based on the steam pressure detected here, and the speed Means for causing the signal from the flow rate controller to follow the signal from the target speed setting device when the steam turbine is controlled by a signal from the controller; and when the steam turbine reaches the target rotation speed, And a means for switching the steam turbine to control by a signal from the flow rate controller.

(Operation) According to the present invention, from the main steam pressure signal 50a detected by the main steam pressure detector 50 and the flow rate setting signal 25a, the target speed setting signal 51 corresponding to the predetermined flow rate is set by the target speed setting device 51.
a is calculated, and while the rotation speed is increasing in accordance with the target ramp signal 41a, the first switch 55 and the second switch 56 are respectively d
Side and b side, and the output of the addition calculator 29 is the target speed setting signal.
51a is followed, and when the predetermined speed is reached, the first and second switching devices 55, 56 are returned to the a side and the c side, whereby the integrator 28 integrates the value of the target speed setting signal 51a as the initial value. Can start.

(Embodiment) An embodiment of the water supply control device according to the present invention will be described below with reference to FIGS. 1 and 2. The same parts as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1, a main steam pressure detector 50 for detecting the pressure inside the reactor 1 is provided in the middle of the branch line from the reactor 1 to the motor-operated valve 5, and the main steam pressure detected here is detected. The signal 50a is input to the target speed setting device 51, where the main steam pressure signal 50a and the set flow rate signal 25a output from the flow rate setting device 25 are calculated, and the target speed setting signal as a follow-up signal of the integration calculator 28 is calculated. 51a is output to the tracking deviation calculator 53.

On the other hand, a first switch 55 is incorporated between the deviation calculator 26, the proportional calculator 27, and the integral calculator 28, and the contact b of the first switch 55 is connected to the tracking deviation calculator 53. ing. A second switch 56 is incorporated between the addition calculator 29 and the target speed setting calculator 31, and the contact d of the second switch 56 is connected to the signal line of the target speed setting signal 51a. ing.

The input signal to the proportional calculator 27 and the integral calculator 28 is either the flow rate deviation signal 26a or the tracking deviation signal 53a,
This is selected by the first switch 55. Here, while the turbine is accelerating, the target ramp signal 41a becomes the set speed signal 31a, and the turbine 9 is accelerated accordingly. At this time, the second switch 56 is on the d side, and the target speed setting signal 51a is given to the target speed signal 29a. At the same time, the first switching device 5
5 is on the b side, and the output of the addition calculator 29 is balanced with the target speed setting signal 51a. When the target ramp signal 41a becomes larger than the target speed signal 29a, the target speed setting calculator 31 outputs the target speed signal to the speed control calculator 32, and the first switching device 55 and the second switching device 56 are respectively set to a and c. Switch to the side. From this time point, the state of flow rate control by the flow rate deviation signal 26a is entered. At this time, the rotation speed of the turbine 9 is such that a predetermined flow rate can flow, the flow rate deviation signal 26a is very small, and the initial value of the integration calculator 28 is the addition calculator.
The output of 29 has a value that balances with the target speed setting signal 51a, and the integration of the flow rate deviation signal 26a is started from this value. Therefore, it is possible to shift to stable flow control without causing a large disturbance in flow control.

As shown in FIG. 2, if a start command is issued at time t ₀ when the time is zero, start of the turbine 9 starts at time t ₁ and its speed rapidly rises according to the speed curve C ₃ . However, since the steam control valve 7 is controlled by the target ramp signal 41a, it rises according to the target ramp characteristic line C ₄ . After that, the target ramp characteristic line C ₄ and the target speed setting signal 51
After passing the point Q where the line a crosses, the rotation speed is controlled according to the target speed setting signal 51a, and the required amount of the pump is secured.

〔The invention's effect〕

As described above, according to the present invention, the time from turbine startup to stable operation can be shortened, and sudden acceleration associated with startup can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a water supply control device according to the present invention, FIG. 2 is a characteristic diagram showing turbine starting characteristics by the device of FIG. 1, and FIG. 3 is a conventional atom in a nuclear reactor power generation system. Fig. 4 is a system diagram of a cooling system during reactor isolation, Fig. 4 is a block diagram of a water supply control device in a conventional cooling system during reactor isolation, and Fig. 5 is a characteristic diagram showing conventional turbine starting characteristics by the device of Fig. 4. is there. 1 ... Reactor, 7 ... Steam control valve, 9 ... Steam turbine, 16 ... Water pump, 17 ... Oil pump, 20 ... Flow rate setting device, 27 ... Speed calculator, 28 ... Integral calculation 29 ... Addition calculator, 31 ... Target speed setting calculator, 32 ... Speed control calculator, 38 ... Ramp signal generator, 50 ... Main steam pressure detector, 51 ... Target speed setter , 55 …… First switch, 56…
… Second switching device.

Claims (1)

[Claims] 1. A steam turbine driven by steam supplied from a steam source through a steam control valve, an oil pump driven by the steam turbine, and supplying control oil to the steam control valve, and the steam source. Water supply pump for supplying cooling water to the water, a speed controller for controlling the speed of the steam turbine according to a ramp function so that the water supply pump flow rate becomes a predetermined flow rate based on a start command, a discharge flow rate and a set flow rate of the water supply pump And a flow rate controller for controlling the steam turbine so that the pump flow rate becomes a predetermined flow rate; a pressure detector for detecting the steam pressure of the steam source, and the steam detected here. When the steam turbine is controlled by a signal from the target speed setter that sets the target rotation speed of the steam turbine based on the pressure and the speed controller A means for causing the signal from the flow rate controller to follow the signal from the target speed setting device, and when the steam turbine reaches the target rotation speed, cancels the following and outputs the signal from the flow rate controller to the steam turbine. And a means for switching to control by the water supply control device.