JPS63201302A - Steam turbine control device - 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 [Purpose of the Invention (Industrial Field of Application) The present invention relates to a steam turbine control device that enables quick and stable startup characteristics to be obtained in a self-starting turbine system or the like.

(Prior Art) Some steam turbine systems are systems in which the power source for establishing oil pressure for turbine control and lubrication is the steam turbine's own rotational energy, that is, the turbine itself drives an oil pump. There is a self-starting turbine system that provides oil for control and lubrication.

This self-starting turbine system is used, for example, as a reactor isolation cooling system (hereinafter referred to as RCIC) turbine pump system, which is an emergency reactor water supply system in a nuclear power plant.

RCIC is a facility in a nuclear power plant that uses the main turbine condenser as a water source and sends cooling water to the reactor when the reactor is isolated due to loss of cooling water from the water supply system, cooling the reactor core and maintaining the reactor water level. As shown in FIG. 5, it is provided as auxiliary equipment for the reactor 2 within the containment vessel 1.

In FIG. 5, water introduced into the reactor through a water supply line 3 is heated while rising inside the reactor 2, and the generated steam is passed through a main steam line 4 to a steam turbine (not shown).
An RCIC steam line 8 having an electric valve 5, a steam stop valve 6, and a steam control valve 7 is branch-connected to the main steam line 4. The steam led to the RCIC turbine 9 via this steam line 8 drives it, and its exhaust gas is returned to the pressure suppression pool 10 attached to the nuclear reactor 2. Further, the main steam line 4 is branched and connected to a pressure suppression pool 10 via a safety relief valve 11 within the containment vessel 1 . The drive shaft 12 of the RCIC turbine 9 has an RC that supplies cooling water from the condensate storage tank 13 to the reactor 2.
The IC pump 14 and an oil pump 15 that supplies oil to the RCIC turbine control device are connected.

In a nuclear power plant equipped with an RCIC configured in this manner, when the reactor 2 is isolated due to reasons such as the reactor water supply being stopped and the reactor water level drops, the electric valve 5 begins to open and is on standby in a fully open state. The RCIC turbine 9 is activated by passing reactor steam through the steam stop valve 6 and the steam control valve 7, which drives the RCIC pump 14 to supply cooling water from the condensate storage tank 13 to the reactor 2. .

Therefore, in an emergency, the RCIC pump 14 must quickly supply a predetermined amount of cooling water to the reactor 2.
The RCIC turbine 9 is required to start as quickly as possible upon receiving the RCIC start signal and to enter stable operation.

FIG. 6 shows a control device for the RCIC turbine 9. As mentioned above, when the electric valve 5 starts to open in response to the RCIC start command, steam flows into the RCIC turbine 9 via the steam stop valve 6 and the steam control valve 7, which are waiting in a fully open state, and the RCIC turbine 9 starts operating. to start. At the same time as the RCIC turbine 9 starts up, the oil pump 15 directly connected to it
is driven, and when it reaches a predetermined rotation speed or higher, the pressure of the control oil 16 supplied from the oil pump 15 is established, and the steam control valve 7 can be controlled via the electro-hydraulic converter 17 and the oil cylinder 18. Become.

In addition, during normal operation, in order to control the discharge flow rate of the RCIC pump 14 at a constant level, a flow rate detector 19 is provided on the discharge side of the RCIC pump 14, and its output is a flow rate signal 19a.
The set flow rate 1k20a output from the flow rate setting device 20 is guided to the deviation calculator 21, and the set flow rate 20a and the flow rate signal 1 are
A flow rate deviation signal 22, which is the difference between the speeds 9a and 9a, is sent to the target speed signal calculator 23.

The target speed signal calculator 23 sends a target speed signal 24 for zeroing the flow rate deviation to the speed control calculator 25. The speed control calculator 25 includes a speed calculator 27 based on the output pulses of the speed detector 26, which is composed of a speed detection gear 26a attached to the RCIC turbine shaft 12 and an electromagnetic pickup 26b provided opposite thereto. The actual speed signal 28 determined by is also input, and a speed control signal 30 that is the deviation from the target speed signal 24 is output. This speed control signal 30 is sent to the electro-hydraulic converter 17 to control the opening and closing of the steam control valve 7.

A ramp signal generator 31 is provided to keep the speed increase rate constant and to suppress overspeed of the RCIC turbine 9 when the RCIC turbine 9 is started. When this ramp signal generator receives a start signal 32, it is connected to the start of opening of the motor-operated valve 5 by a limit switch provided on the motor-operated valve 5, and starts, and a ramp signal 33 that increases at a constant slope with time is output to a calculator. Send to 34. Similarly, a starting bias signal 36 from a starting bias generator 35 which is activated by the starting signal 32 is also input to the computing unit 34 . When these re-inputs are added, the computing unit 34 outputs a ramp signal with a constant bias as a startup waiting speed command 38. Further, the target speed signal calculator 23 always selects a signal with a low value among the speed signals corresponding to the startup waiting speed command 38 and the flow rate deviation signal 22, and forms the target speed signal 24.

FIG. 7 shows the rapid start-up characteristics of the RCIC turbine using the conventional control method described above.

In the figure, time t. When the electric valve 5 opens due to the generation of the start signal 32, the steam control valve 7 is fully open, so the RC
The IC turbine 9 starts speeding up.

At the same time, the startup standby speed command 38 begins to rise as a ramp signal with a constant bias. The steam regulator valve 7 is controlled according to the start-up speed command 38, but since the oil pressure of the control oil 16 is not established until the rotational speed of the RCIC turbine 9 reaches a certain level, the closing operation of the steam regulator valve 7 is delayed, and the RC
The rotational speed of the IC turbine 9 indicates a primary peak n. The value of this primary peak n is determined by the reactor pressure of reactor 2, which is the steam source, and
It depends on the value of the startup speed command 38. After passing through the primary peak n, the RCIC turbine 9 speeds up according to the start-up speed command 38, and at time t1, the target speed signal 24 is switched to the flow rate deviation signal 22 by the target speed signal calculator 23, and the RCIC turbine 9 shifts to rated operation.

In the conventional RCIC system described above, the RCIC
When the pump 14 is loaded and when the pump 14 is started, the energy that flows into the steam control valve 7 having the same opening degree differs depending on the reactor pressure of the nuclear reactor 2. Therefore, as shown in FIG. 8, when the furnace pressure increases, the energy flowing into the RCIC turbine 9 at startup increases, so the primary peak increases from n to n p2.
As the load on the RCIC pump 14 increases, the target rotational speed of the RCIC turbine also increases for the same flow rate request.

Therefore, according to the conventional control system, the transition time (1-10) from the startup of the RCIC turbine 9 to the rated operation based on the flow rate deviation signal 22 becomes longer as the reactor pressure increases, and this rated operation transition time (tl -to), if the starting bias 36, which is the bias of the starting waiting speed command 38, is increased, the primary peak n of the rotation speed of the RCIC turbine 9 at startup increases, and in some cases, the turbine speed due to overspeed increases. This may result in a trip and a startup failure.

(Problems to be Solved by the Invention) The present invention provides a steam turbine control device that reduces the time from generation of a startup command to transition to rated operation during rapid startup of the above-mentioned self-starting turbine, and provides stable startup characteristics. The purpose is to provide.

[Structure of the Invention] (Means for Solving the Problems) A steam turbine control device of the present invention controls a steam control valve in a steam turbine driven by steam supplied from a steam source via the steam control valve. An oil pump for supplying control oil to the steam source and a water supply pump for supplying cooling water to the steam source are directly connected, and a startup command causes the steam turbine to operate so that the flow rate of the water supply pump reaches a predetermined value. In a steam turbine control device that performs speed control according to a predetermined ramp function, the timing to start speed control using the ramp function at startup is determined by detecting a negative change in the rate of change in the steam turbine rotation speed, and the initial timing of the ramp function at the start of speed control is The present invention is characterized in that the value is corrected in accordance with the pressure of the steam source at the time of starting the steam turbine.

(Function) As described above, the present invention detects the first negative change in the rotation speed change rate at the time of startup of the steam turbine, and uses the detection signal to generate a ramp signal containing a bias that is a startup waiting speed command. Since a means is provided for starting the steam turbine and correcting the bias to an appropriate value depending on the pressure of the steam source of the steam turbine, quick and stable startup characteristics can be obtained.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the steam turbine control system of the present invention. In the figure, parts indicated by the same reference numerals as in FIG. 6 indicate the same or corresponding parts, and explanations will not be given unless necessary. Omitted.

In FIG. 1, the actual opening signal 28 from the speed calculator 27
enters the speed differentiator 40, and the speed differential signal 41 is sent to the comparator 4.
Output to 2. The speed control start command 43 outputted from the comparator 42 functions as a switching signal for the steam control valve closing bias signal 45 outputted from the bias signal generator 44, and also functions as a switching signal for the steam control valve closing bias signal 45 outputted from the bias signal generator 44.
is input.

The primary peak rotational speed 47 output from the storage device f46 is the bias signal 4 output from the bias signal generator 48.
9 is input to the arithmetic unit 50.

In the device of the present invention equipped with the above-mentioned additional mechanism, R
After the activation signal for the CIC turbine 9 is generated, the electric valve 5 is opened, and steam flows through the fully open steam stop valve 6 and the steam control valve 7, and the RCIC turbine 9 is activated.

At this time, in order to suppress the overspeed of the RCIC turbine 9, the bias signal generator 44 outputs the steam regulating valve closing bias signal 45 as the startup waiting speed command 38, and the steam regulating valve 7 is quickly moved from the fully open state to the closing direction. let

FIG. 2 shows the startup characteristics of the RCIC turbine 9 according to this embodiment. By controlling the steam control valve 7 in this manner, the primary peak of the turbine rotational speed is suppressed to a safe value so as not to overspeed.

When the actual speed signal 28, which is the output of the speed calculator 27, is input to the speed differentiator 40, a speed differential signal 41 is calculated and output. This signal is input to the comparator 42, and when the speed differential signal 41 becomes negative, the comparator 42 outputs a speed control start command 43.
Output. The speed start command 43 detects the timing of a negative change in the RCIC turbine actual speed load factor, that is, the primary peak of the rotational speed at the time of starting the RCIC turbine 9 as shown in FIG. This speed control start command 43 causes the ramp signal generator 31 to generate a ramp signal 33, and also converts the start speed command 38 into the steam control valve closing bias signal 4.
5 to the arithmetic unit 34 side.

Note that the calculator 34 adds the ramp signal 33 and the starting bias signal 36, but as the starting bias signal 36, the actual speed signal 28 when the speed control start command 43 is generated is stored in the storage device w.
46, that is, the value obtained by subtracting the bias signal 49 output from the bias signal generator 48 from the primary peak rotation speed is used.

With the above configuration, as shown in Figure 2, the RC
It is possible to provide stable control characteristics by providing a ramp signal with an appropriate bias value as the start-up speed command 38 according to the primary peak rotation speed, which varies depending on the pressure of the steam source of the IC turbine 9, that is, the furnace pressure. It becomes possible.

FIG. 3 shows another embodiment of the present invention. In this embodiment, a pressure detector 51 for detecting the internal pressure of the reactor 2 is connected, and a reactor pressure signal 5 is output from this detector.
2 is input to the starting bias generator 35.

In the embodiment of FIG. 3 configured in this way, the RCIC
The control method until the startup rotation speed of the turbine 9 reaches its primary peak is the same as that shown in FIG.

After the rotational speed reaches its primary peak, a speed control start command 43 is issued.
, the startup waiting speed command 38 is switched to a ramp signal 33 having a constant bias, but in this embodiment, a startup bias generator 35 is provided, and a reactor pressure signal 5 indicating the pressure of the reactor 2 is provided in this embodiment.
2 and start bias signal 36 as shown in FIG.
Correct the value to an appropriate value depending on the furnace pressure. As a result, the RCIC turbine 9, which obtains a speed command having an appropriate value according to the furnace pressure, is stably controlled until the transition to rated operation.

[Effects of the Invention] As described above, according to the present invention, overspeed at startup of a self-starting steam turbine can be suppressed, and stable and quick startup can be achieved regardless of the magnitude of the pressure of the steam turbine steam source. It is possible to obtain a steam turbine control device that is capable of

[Brief explanation of the drawing]

1 and 3 are block diagrams of a steam turbine control device according to an embodiment of the present invention, FIGS. 2 and 4 are graphs explaining the effects of the embodiment of FIGS. 1 and 3, and FIG.
The figure shows an RCIC, which is an example of a self-driven turbine system.
FIG. 6 is a block diagram showing a conventional RCIC turbine control device, and FIGS. 7 and 8 are graphs showing control characteristics by the conventional control device. 1...Containment vessel 2...Reactor 3...Water supply line 4...Main steam line 5 ......Motorized valve 6...Steam stop valve 7...Steam control valve 8...RCIC steam line 9...
...RCI C turbine 14...R
CIC pump 15... Oil pump 17... Electro-hydraulic converter 18... Oil cylinder 19... Flow rate detector 20...Flow rate setter 21...Deviation calculator 23...Target speed signal calculator 25...
... Speed control calculator 26 Speed detector 27 Speed calculator 31 Ramp signal generator 34...
......Arithmetic unit 35......Starting bias generator 40...
... Speed differentiator 41 ... Speed differential signal 42 ... Comparator 43 ... Speed control start command 44. ...
...Bias signal generator 45...
Steam control valve closing bias signal 46... Memory device 47... Primary peak rotation speed 48...
...Bias signal generator 49...
Bias signal 50...... Arithmetic unit 51... Pressure detector 52... Furnace pressure signal Applicant Toshiba Corporation Agent Patent attorney Su Yamasa - 1st Garden Figure 2 Figure 5 Figure 6

Claims (3)

[Claims] (1) An oil pump that supplies control oil for controlling the steam regulating valve to a steam turbine driven by steam supplied from the steam source via the steam regulating valve, and supplying cooling water to the steam source. It is directly connected to the water supply pump for
In a steam turbine control device that controls the speed of the steam turbine according to a predetermined ramp function so that the flow rate of the feedwater pump reaches a predetermined value in response to a startup command, the speed control start timing using the ramp function at startup is controlled by changing the speed of the steam turbine. 1. A steam turbine control device, wherein the initial value of the ramp function at the time of starting speed control is corrected in accordance with the pressure of the steam source at the time of starting the steam turbine. (2) a speed differentiator that inputs the actual speed signal from the speed calculator and outputs a speed differential signal; a comparator that outputs a speed control start command based on the speed differential signal; a storage device that outputs a primary peak rotational speed based on an actual speed signal; a computing unit that inputs a steam control valve closing bias signal from a bias signal generator and the primary peak rotational speed and outputs a starting bias signal; The steam turbine control device according to claim 1, further comprising a bias signal generator that outputs a steam control valve closing bias signal to a ramp signal generator based on a control start command. (3) A speed differentiator that inputs the actual speed signal from the speed calculator and outputs a speed differential signal, a comparator that outputs a speed control start command based on the speed differential signal, and a pressure that detects the furnace pressure. a detector, a starting bias signal generator that inputs the furnace pressure signal from the pressure detector and outputs a starting bias signal to a computing unit, and generates a steam control valve closing bias signal based on the speed control start command. The steam turbine control device according to claim 1, further comprising a bias signal generator that outputs an output toward the ramp signal generator.