JPH059605B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a control device for a steam turbine that requires rapid startup, such as in a turbine pump system of a nuclear reactor isolation cooling system, for example.

[Technical background of the invention and its problems]

In general, in steam turbine plants, for example, geothermal power plants have only enough DC power to use for a short period of time such as drive signals, turbines for in-house backup power supply in emergencies, and emergency power supplies in nuclear power plants. A steam turbine plant has a steam source, such as the reactor isolation cooling turbine pump system, which is one of the backup reactor auxiliary systems, but there are also hydraulic sources for turbine control and lubrication. Some turbines have no other auxiliary power source and function to supply oil by driving the oil pump themselves.

In other words, Figure 4 shows a nuclear reactor that cools the reactor core by supplying cooling water from the condensate storage tank to the reactor to maintain the reactor water level when the reactor is isolated from the turbine condenser. This is a system diagram of the isolation cooling system, and the reactor 2 installed in the containment vessel 1 includes:
Coolant is supplied via a water supply line 3, and the steam generated therein is supplied via a main steam line 4 to a main steam turbine (not shown). On the other hand, the main steam line 4 includes a reactor isolation cooling system steam line 5.
is branched, and part of the main steam passes through an electric valve 6, a steam stop valve 7, and a steam control valve 8 provided in the steam line 5 of the steam reactor isolation treatment cooling system.
Reactor isolation cooling system turbine (RCIC turbine)
9 and then into the steam turbine exhaust line 1
0 and is returned to the pressure suppression pool 11. Also,
The RCIC turbine 9 is directly connected to an oil pump 12 that sends lubricating oil to the turbine control device and a reactor isolation cooling system water supply pump 13 that feeds cooling water in the condensate storage tank to the reactor 2. .

In the reactor power generation system, when the reactor 2 is isolated in an emergency such as when the reactor water supply is stopped, and the reactor water level drops and the reactor isolation cooling system activation signal is output, the electric valve 6 is activated. The main steam is supplied to the RCIC turbine 9 through the steam stop valve 7 and the steam control valve 8 which are already fully open and waiting, the RCIC turbine 9 is driven, and the reactor isolation cooling system feed water pump 13 is supplied with the main steam. Therefore, cooling water is supplied from the condensate storage tank to the nuclear reactor 2 to cool the reactor core.

By the way, FIG. 5 is a system diagram of the control device for the reactor isolation cooling system, and when the reactor isolation cooling system activation signal a is generated, the activation signal a is sent to the ramp signal calculator 14. The ramp signal b is output from the ramp signal calculator 14 and applied to the speed request signal calculator 15, which is a low value priority circuit. On the other hand, a flow rate detector 16 is provided on the discharge side of the reactor isolation cooling system water supply pump 13, and its flow rate signal c is applied to a flow rate calculator 17, and the flow rate signal c is applied to a speed request signal calculator 17 as a flow rate request signal d. 1
5, and the low value signal together with the ramp signal b is added to the speed control signal calculator 18 as the speed request signal e.

The speed control signal calculator 18 is connected to the RCIC via a rotation speed detection gear 19 provided on the turbine shaft, an electromagnetic pickup 20, and a rotation speed calculation device 21.
An actual speed signal f of the turbine 9 is also applied, and a deviation signal from the speed request signal e is applied as a speed control signal g to the electro-hydraulic converter 22.
Based on the output, control oil supplied by the oil pump 12 is controlled to be supplied to and discharged from the oil cylinder 23, and the opening degree of the steam control valve 8 is controlled.

That is, in the initial stage of startup of the RCIC turbine 9, the ramp signal b passes through the speed request signal calculator 15 and becomes the speed request signal so as to keep the speed increase rate of the turbine constant, and the ramp signal b becomes the speed request signal via the speed control signal calculator 18. 22, thereby controlling the opening degree of the steam control valve 8. In this way
When the RCIC turbine 9 starts up and the amount of water supplied from the reactor isolation cooling system water supply pump 13 increases and the flow rate request signal d reaches a predetermined value, this flow rate request signal d is used as a speed request signal by the speed request signal calculator 15. The opening of the steam control valve 8 is controlled based on the signal.

However, in such equipment, although it is necessary to always start up quickly, the oil pump 12 is directly connected to the turbine shaft, so the RCIC
It takes some time for the rotational speed of the turbine 9 to reach a certain rotational speed and the oil pressure necessary to operate the oil cylinder 22 is established, and if the rotational speed of the RCIC turbine 9 exceeds the rated rotational speed. There are problems such as an abnormal initial peak rotation speed.

In other words, Figure 6 is a diagram showing each state value at the time of startup of the reactor isolation cooling system, and as mentioned above,
Since the RCIC turbine is started with the steam control valve fully open so that a large starting torque can be obtained, the turbine rotational speed increases rapidly as shown in FIG. Then, the steam control valve is operated in the fully closed direction only when the turbine rotation speed exceeds the ramp signal and the control oil pressure is established as the turbine rotation speed increases. In other words, there is a time delay before the steam control valve operates. Therefore, during this period, the rotation speed of the turbine increases rapidly, generating an abnormal initial peak rotation speed n that exceeds the rated rotation speed, which may cause an emergency stop through the emergency governor, etc. , there are problems such as the nuclear reactor becoming even more dangerous.

[Purpose of the invention]

In view of these points, the present invention provides a control for a steam turbine such as an RCIC turbine that prevents sudden overspeed and vibration from occurring during startup, and enables a stable increase in rotational speed. The purpose is to obtain equipment.

[Summary of the invention]

The present invention provides a method for controlling the opening of the steam regulating valve, which is kept fully open before starting the turbine, using a ramp signal and a low value signal of a flow rate request signal when starting the turbine. In the turbine control device, a valve closing signal calculator is provided which is activated by a turbine start signal and outputs a valve closing signal until the turbine reaches a predetermined operating state, and the steam valve closing signal is generated by a low value priority circuit as described above. The system is characterized in that a speed request signal calculation unit that outputs a speed request signal to the steam control valve is inputted together with a ramp signal and a flow rate request signal. After that, the steam control valve is operated in the direction of ramp control and flow rate control.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3. Note that the same parts as in FIG. 5 are given the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 1, reference numeral 24 is a valve close signal calculator, and when the reactor isolation cooling system activation signal a is input to the valve close signal calculator 24, a valve close signal i is output. The valve closing signal i is applied to the speed request signal calculator 15 along with the ramp signal b from the ramp signal calculator 14 and the flow rate request signal d from the flow rate calculator 17. Further, the actual speed signal f from the rotation speed calculator 21 and the ramp signal b from the ramp signal calculator 14 are also added to the valve opening signal calculator 24, and the actual speed signal f
When the value exceeds the ramp signal b, the output of the valve closing signal i is stopped. The rest is completely the same as the conventional device shown in FIG.

When the reactor isolation cooling system activation signal is generated, the solenoid valve 6 is opened and the above-mentioned power is supplied to the RCIC turbine 9 to start its activation, and the activation signal a is transmitted to the ramp signal calculator 14 and the valve. The ramp signal b and the valve close signal i are input to the closing signal calculator 24 and sent to the speed request signal calculator 15, respectively. The speed request signal calculator 15 selects the lowest valve closing signal i from the ramp signal b, the valve closing signal i, and the flow rate request signal d, and calculates the valve closing signal as a negative speed request signal e as a speed control signal. input into the device 18.

By the way, in the speed control signal calculator 18,
Although the turbine rotational speed is still Ormp, the speed request signal e is negative, so a speed control signal that closes the steam control valve is output, and this signal is sent to the electro-hydraulic converter 22. However, in this case, since oil pressure has not yet been established, the steam control valve 8 is not closed.

Therefore, when the RCIC turbine 9 starts up and the oil pressure increases, at the same time, the oil cylinder 23 is activated via the electro-hydraulic converter 22, the steam control valve 8 is controlled in the closing direction, and the amount of steam flowing into the turbine is reduced. As a result, the rate of increase in turbine speed becomes slower.

In this way, the rotational speed of the turbine increases, and when this rotational speed reaches a point where it matches the rotational speed required by the lamp signal (point p in FIG. 2), the valve closing signal calculator 24 outputs a valve closing signal i. The output of is suddenly cut off, and the speed request signal calculator 15 receives only the ramp signal b and the flow rate request signal d. However, at this point, the rotational speed of the turbine has not reached the rated rotational speed, so the ramp signal b is selected and applied to the speed control signal calculator 18. By the way, in this case, the turbine rotation speed is higher than the ramp signal, so
A valve closing signal is subsequently applied to the electro-hydraulic converter 22, and the steam control valve 8 is subsequently operated to close.

Therefore, the turbine rotational speed then reaches the initial peak rotational speed and begins to decrease, and when the turbine rotational speed decreases below the ramp signal, the speed control signal in the direction of opening the steam control valve is sent from the speed control signal calculator 18 to the electro-hydraulic converter. The steam control valve 8 is operated in the opening direction, and thereafter the speed is controlled sequentially in accordance with the ramp signal and the flow rate request signal.

In the above embodiment, the fully open steam control valve is operated in the closing direction almost simultaneously with the start of turbine startup, so as shown in FIG.
The initial peak rotational speed of the turbine can be kept low compared to conventional devices, and the rapid start-up time can be controlled without delay.

Furthermore, in the above embodiment, switching between the valve close signal and the ramp signal is determined based on the turbine rotation speed and the ramp signal, but when the steam pressure etc. are variable, the steam control valve is fully opened. If there is a possibility that this may occur, as shown in FIG. 3, a potentiometer 25 is provided on the operating rod 23a of the oil cylinder 23 for operating the steam control valve 8, and the control valve opening signal k is used to calculate the valve closing signal. The valve closing signal i and the ramp signal b may be switched between the valve closing signal i and the ramp signal b by inputting the signal into the signal generator 24 and controlling the opening/closing of the steam control valve or the rate of stroke change, regardless of the turbine rotational speed.

Note that in both steam and steam embodiments, a control device for an RCIC turbine in a reactor isolation cooling system in a nuclear power plant has been described.
Geothermal power generation systems that only have DC power,
Although it has a so-called steam source, such as a turbine for supplying in-house backup power in an emergency, it does not have any other hydraulic power source or auxiliary power source for turbine control or lubrication, and rotates the oil pump by driving itself. It can also be applied to steam turbine systems that function to supply oil.

〔Effect of the invention〕

As explained above, in the present invention, a valve closing signal calculator is provided to control the steam control valve in the closing direction immediately after starting the turbine, so that the rotation speed is controlled within a short time after starting the steam turbine. This makes it possible to prevent sudden overspeed and vibrations during startup. Moreover, as mentioned above, since the valve closing signal calculator is simply provided and its output signal is added to the speed request signal calculator, the structure is extremely simple and there is almost no effect on other mechanisms. be able to.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of the steam turbine control device of the present invention, Fig. 2 is a diagram of each state at the time of turbine startup in the device of the present invention, Fig. 3 is a system diagram showing another embodiment of the present invention, and Fig. 4 is a system diagram of a reactor isolation cooling system in a nuclear power plant, Figure 5 is a system diagram of a conventional reactor isolation cooling system turbine control device, and Figure 6 is a diagram of a conventional reactor isolation cooling system turbine at startup. FIG. 8...Steam control valve, 9...RCIC turbine, 1
2... Oil pump, 13... Reactor isolation cooling system water supply pump, 14... Lamp signal calculator, 15...
Speed request signal calculator, 17...Flow rate calculator, 18
... Speed control signal calculator, 21... Rotation speed calculator, 22... Electro-hydraulic converter, 24... Valve closing signal calculator.

Claims (1)

[Claims] 1. A steam control valve that is fully open before starting a turbine and is driven by the oil pressure of an oil pump driven by the turbine is controlled by a ramp signal and a flow rate request signal when starting the turbine. In a steam turbine control device that controls the opening degree of the steam control valve based on a low value signal, a valve closing signal that is activated by a turbine start signal and outputs a valve close signal until the turbine reaches a predetermined operating state is provided. A signal calculator is provided, and the valve close signal is inputted together with a ramp signal and a flow rate request signal to a speed request signal calculation section which is a low value priority circuit and outputs a speed request signal to the steam control valve. A steam turbine control device characterized by: 2. The steam turbine control device according to claim 1, wherein the valve closing signal is output until the turbine rotation speed exceeds the ramp signal. 3. The steam turbine control device according to claim 1, wherein the output of the valve closing signal is stopped depending on the opening degree of the steam control valve or the rate of change in stroke.