JPS63243404A - Control device for steam turbine - Google Patents

Abstract

PURPOSE:To ensure the stable speed control of a turbine at the startup thereof by applying a turbine drive startup signal as a startup signal to a ramp signal generator in outputting a ramp function determining the speed of a steam turbine. CONSTITUTION:The reactor core isolation cooling system (RCIC) of a nuclear power plant has an RCIC turbine 4 within an RCIC steam pipe 6 branched from a main steam pipe, and power generated with the turbine 4 is used to operate a feed water pump 9, thereby supplying cooling water to a nuclear reactor 2. Also, the turbine 4 drives an oil pump 11 and oil delivered therefrom is fed to the electricity-oil converter 25 of a steam governing valve 14 as control oil. The turbine 4 is so controlled in speed as to keep the predetermined flow rate of the feed water pump 9 on a startup instruction, in accordance with the predetermined ramp function. In this case, a turbine drive startup signal from a speed operating device 24 is applied as a startup signal to a ramp signal generator 26 generating said ramp function.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a steam turbine control device, and particularly to a steam turbine control device suitable for obtaining quick and stable startup characteristics.

(Prior Art) Generally, a steam turbine is equipped with a high-pressure hydraulic source that supplies control oil or lubricating oil for turbine control or bearing lubrication. In order to supply these control oils or lubricating oils at a constant pressure, the power of the oil pump must be stable, and there are systems in which the steam turbine itself drives the oil pump.

Examples of this system include the RCIC turbine used in the reactor isolation cooling system (hereinafter referred to as RCIC) as a backup for emergencies in nuclear power plants, and the in-house backup power source for emergencies in nuclear power plants, thermal power plants, etc. There are supply turbines, etc.

Hereinafter, the system configuration will be explained using an RCIG turbine as a representative example of these turbines. RCIC is a safety facility for core cooling that functions to maintain the water level in the reactor by replenishing cooling water from the condensate storage tank to the reactor when the reactor is isolated from the condenser. be.

In FIG. 3, the reference numeral 1 in the figure is a containment vessel, and a nuclear reactor 2 is housed in this containment vessel 1.
A pressure control pool 3 is provided below. on the other hand,
Reference numeral 4 indicates an RCIC turbine as a prime mover of the RCIC, and this RCIC turbine generates working steam through an RCIC steam pipe 6 branched from a main steam pipe 5 that leads steam generated in the reactor 2 to a main turbine (not shown). The pressure control pool 3 is configured so that the exhaust gas is returned to the pressure control pool 3 through an exhaust pipe 7 to generate power. A water supply pump 9 is directly connected to the drive shaft 8 of the RCIC Tahin 4, and cooling water sent from a condensate storage tank (not shown) is passed through a water supply pipe 10.
The reactor 2 is supplied through the reactor 2.

Further, reference numeral 11 denotes an oil pump, which is provided integrally with the impeller on the opposite side of the drive flIII 8 where the water supply pump 9 is provided. Note that numerals 12, 13, and 14 in the figure represent an isolation valve, a steam stop valve, and a steam control valve, and the numeral @15 represents a safety valve, respectively.

In the above configuration, if the reactor 2 is isolated in an emergency such as when the water supply to the reactor 2 is stopped and the water level drops,
The isolation valve 12 begins to open, and the steam generated in the reactor 2 is guided to the RCIC turbine 4 through the steam stop valve 13 and steam control valve 14, which are already on standby in the inquired state, and startup is started. The rotation of the RCIC turbine 4 turns the drive shaft 8, and when the water supply pump 9 starts operating, cooling water from the condensate storage tank (not shown) is supplied to the reactor 2 through the water supply pipe 10 to cool the reactor core. It looks like this.

In this way, in the RCIC, it is most important that upon receiving the start signal, the RCIC turbine 4 starts up immediately, the water supply pump 9 starts up quickly, and sends a predetermined amount of cooling water to the reactor 2.

Incidentally, the starting characteristics of the RCIC turbine 4 are expressed on a time chart as follows. That is,
In FIG. 4, if the start command is issued at time 10 when the time path is zero, then the isolation valve 12 is opened and the RCIC turbine 4 is started at a slightly delayed time t1, and the RCIC turbine 4 is started from the idle speed n1. The rotational speed is controlled so as to gradually increase by -F according to the target lamp characteristic line which is extended with a slope. On the other hand, the flow rate of the feed water pump 9 gradually increases from zero, which is indicated by the 100% value of the flow rate deviation signal, along the flow rate characteristic line Q, which is indicated by a downward slope of the decrease in the flow rate deviation signal value, and at time t2, the flow rate of the RCIC turbine 4 increases. It intersects with the actual speed curve R. This intersection point P becomes a stable speed point, and from then on, the RCIC turbine 4 operates at a speed corresponding to this stable speed point P.
is driven. That is, the lamp is operated at the rated speed S, separated from the target lamp characteristic line.

(Problem to be solved by the invention) As described above, the starting characteristics of the RCIC turbine 4 are that it starts from zero speed, rapidly increases the speed, reaches the intersection P, stops increasing the speed, and then remains constant. It will be done. For this purpose, an appropriate idle speed n1 is determined, and a ramp function is also determined as a target ramp characteristic line. However, speed changes can be sudden, and if proper control is not performed,
There is a risk that the LCIC turbine 4 will cause an overspeed trip. That is, normally, the lamp signal generator that outputs the target lamp characteristic line works by a start signal given based on the signal output when the limit switch attached to the isolation valve 12 is operated, but in this case, the limit switch is activated. lacks accuracy due to mechanical setting errors. On the other hand, when the LCIC turbine 4 is started, the steam drain accumulated between the isolation valve 12 and the inlet of the LCIC turbine 4 and the RCIC steam pipe 6 It is easy to be affected by the fact that the temperature of the device has dropped to the ambient temperature. For this reason, the time point at which the ramp signal generator is activated and the time point at which the speed of the RCIC turbine 4 starts to increase are time-shifted, making it impossible to obtain a desired speed curve. For example, as shown in Figure 4, the speed curve R may exceed the rated speed S (S
1 point) RCIC turbine causes overspeed trip. Also, as shown in the speed curve R', there is a large time lag,
Shows an unstable tendency.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a steam turbine control device that can maintain stable speed control during startup of a self-driven steam turbine.

[Structure of the Invention] (Means for Solving the Problems) A steam turbine control device according to the present invention has a steam turbine driven by steam supplied from a steam source through a steam control valve, and has a steam turbine driven by steam supplied from a steam source through a steam control valve. At least an oil pump that supplies high-pressure control oil to the control section of the steam control valve and a water supply pump that supplies cooling water to the steam source are connected, and the discharge flow rate of the water supply pump is controlled by a startup command. In a steam turbine control device that controls the speed of a steam turbine according to a predetermined ramp function so that the speed of the steam turbine reaches a predetermined value, a ramp signal generator is used to control the speed of the steam turbine in accordance with a predetermined ramp function. This is characterized in that a turbine drive start signal given based on the rotational speed of the turbine is added as a starting signal.

(Function) In the present invention, the timing for outputting the ramp function that defines the speed of the steam turbine is when the turbine drive start signal given from the means for detecting the rotational speed of the steam turbine is given to the ramp signal generator. . In other words, matching with the startup timing of the steam turbine is achieved. This results in
The peak speed rise of the steam turbine is kept low, eliminating the risk of the steam turbine causing an overspeed trip. Furthermore, since the turbine speed follows the ramp signal at an early stage of startup, it is possible to shift to normal rotation speed control in a short time, and cooling water is smoothly supplied to the reactor.

(Example) An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, a nuclear reactor 2 and an RCIC turbine 4 are connected via an RCIC steam pipe 6, and it is conventional to provide an isolation valve 12, a steam stop valve 13, and a steam control valve 14 in this path. It is similar to

Furthermore, the provision of the water supply pump 9 directly connected to the drive shaft 8 of the RCIC turbine 4 and the provision of the oil pump 11 are also the same as in the prior art.

In this embodiment, the following control elements are added to the above configuration. A flow rate signal q which is the output of a flow rate detector 16 provided on the discharge side of the water supply pump 9 in order to control the discharge flow rate to a constant level.
1 and the set flow iqO output from the flow rate setter 17 are compared by the deviation calculator 18, and the result is provided to the target speed signal calculator 19 as a flow rate deviation signal q2. The target speed signal calculator 19 calculates a target speed signal VQ to make the flow rate deviation zero.
is created and added to the speed control calculator 20.

The speed control calculator 20 uses a speed detector 23 based on the output pulses of a speed detector 23, which is composed of a speed detection gear 21 attached to the drive shaft 8 and an electromagnetic pickup 22 installed opposite the gear, to a speed detector 24. The actual speed signal V1 representing the actual speed determined by is,
The opening and closing of the steam control valve 14 is controlled via the electro-hydraulic converter 25.

On the other hand, a ramp signal generator 26 is provided to keep the speed increase rate, that is, the acceleration, constant when the RCIC turbine 4 is started. A turbine drive start signal y from the speed calculator 24, which receives the output signal of the speed detector 23, is input to the ramp signal generator 26, and is used as a starting signal for the ramp circuit. This activation signal is used by the lamp signal generator 2.
6, a ramp signal ro that increases at a constant rate is output to the calculator 27. Similarly, an idle signal aO from an idle signal calculator 28, which is activated by a start signal, is also input to the calculator 27. The idle signal aO is for giving the speed value of the ramp signal ro at time zero (immediately after the start of activation), that is, the idle speed value, and the calculator 27 follows a desired ramp function from this and the ramp signal ro. Create a target ramp signal r1,
Output to one target speed signal calculator. The target speed signal calculator 19 always selects the signal with the lowest value among the speed signals corresponding to the target ramp signal r1 and the flow rate deviation signal q2, and sets it as the target speed signal {circle over (2)}0.

In addition, the reference numeral 29 in the figure indicates a steam regulating valve oil cylinder, and the steam regulating valve 14 is controlled via the electro-hydraulic converter 25 only when the pressure of the control oil supplied from the oil pump 11 is established. is now possible.

Next, the operation will be explained with reference to FIG.

FIG. 2 shows the startup characteristics of this embodiment of the RGIC turbine 4 in a similar manner to FIG. 4, in which the speed curve R rises from time 10 when time elapses at zero and extends at a steep slope from the idle speed n1. It is shown as following the target lamp characteristic line quickly. That is, the output signal of the speed detector 23 that detects the actual speed of the RCIC turbine 4 in this embodiment not only generates the speed control signal @S, but also serves as a starting signal for the ramp signal generator 26 and the idle signal calculator 28. is also used, which allows RCIC
The startup timing of the turbine 4 and the lamp signal are matched. Further, as is clear from the figure, since the ramp rate can be increased compared to the conventional one (see FIG. 4), the initial peak of the turbine speed is lowered, and the risk of overspeed trip is greatly reduced. Needless to say, since the turbine speed follows the ramp signal at an early stage, the stable speed point P is reached in a short period of time, and thereafter the RCIC turbine 4 may fail to start because it is shifted to rotation speed control. It can be said that there is almost no sex.

In this way, the start-up of the water supply pump 9 becomes smooth, and obstacles to securing the cooling water supplied to the atomic path 2 can be eliminated.

[Effects of the Invention] As described above, in outputting a ramp function that defines the speed of a steam turbine, the present invention uses a turbine drive start signal given to the ramp signal generator based on the rotational speed of the steam turbine as a starting signal. Since the cooling water is added, the speed control at the time of starting the turbine can be maintained stably, and excellent effects such as preventing loss of cooling water during an emergency in a nuclear power plant can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the steam turbine control device according to the present invention, Fig. 2 is a starting characteristic diagram of a steam turbine by the control device of the present invention, and Fig. 3 is a nuclear reactor in a conventional nuclear power plant. A system diagram showing an isolated cooling system, and FIG. 4 is a starting characteristic diagram of a steam turbine in the prior art. 4...RCIC turbine 9...
...Water pump 11...Oil pump 14...Steam control valve 19...Target speed signal calculator 20...
... Speed control calculator 21 ... Speed detection gear 22 ... Electromagnetic pickup 24 ...
... Speed calculator 25 ...... Electro-hydraulic converter 26 ...... Ramp signal generator 27 ...
...Calculator 28...Idle signal calculator 29...
・・・・・・Steam control valve oil cylinder agent Patent attorney Nori Chika
Ken Yudo Hirofumi Mitsumata &ft (m) 2nd illustration 112! J Figure 3 Figure 4

Claims (1)

[Claims] It has a steam turbine driven by steam supplied from a steam source through a steam control valve, and an oil pump that supplies high-pressure control oil to at least a control section of the steam control valve. and a feedwater pump that supplies cooling water to the steam source, and the steam turbine is operated at a speed according to a predetermined ramp function so that the discharge flow rate of the feedwater pump reaches a predetermined value in response to a startup command. In a steam turbine control device that is adapted to be controlled, in order to output a ramp function that defines the speed of the steam turbine, a turbine drive start signal that is given to the ramp signal generator based on the rotational speed of the steam turbine is activated. A steam turbine control device characterized in that signals are added as signals.