JPS63223306A - Steam turbine controller - Google Patents

Abstract

PURPOSE:To reduce a time required for entering into the stable operation of a steam turbine in the case that the pressure of a steam source is low by detecting the pressure of a steam source to which cooling water is supplied, and adding a bias signal to a desired speed of the steam turbine according to the detected pressure. CONSTITUTION:An RCIC (Reactor Core Isolation Cooling) water feeding pump 12 is connected to an RCIC turbine 8 driven by steam which is supplied through a steam regulation valve 6 from a rector 2 serving as a steam source. And a speed is controlled in such a way as to increase the desired speed of the turbine 8 in accordance with a predetermined ramp function. In this device, there is provided a pressure detector 28 for detecting the pressure of the reactor 2, and according to a furnace pressure signal 29 obtained thereby, a speed bias signal 31 which is generated in a speed bias generator 30 is added to a speed deviation arithmometer 25 as a bias signal with respect to a desired speed signal 24. Thereat, the speed bias generator 30 outputs a large speed bias signal 31 in the case that a pressure in the reactor 2 is, for example, low.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to a steam turbine control device for obtaining rapid gas stable start-up characteristics.

(Prior Art) A steam turbine system to which the present invention is applied will be described using a reactor isolation cooling system (hereinafter referred to as RCIC) turbine system as a representative example.

RCIC is a reactor auxiliary system that supplies cooling water from the condensate storage tank to the reactor to maintain the reactor water level and cool the reactor core when the reactor is isolated from the turbine condenser. It is a facility with a system configuration as shown in Figure 2.

In FIG. 2, the RCIC is installed as auxiliary equipment for a nuclear reactor 2 housed in a containment vessel 1.

The steam generated in the nuclear reactor 2 is branched from the main steam line 3 and sent to the RCIC turbine (hereinafter simply referred to as the turbine) via the RCIC steam line 7 having an electric valve 4, a steam stop valve 5, and a steam control valve 6. )8 to drive it. Water is supplied to the reactor 2 via a water supply line 9.

The shaft of the turbine 8, that is, the RCIC turbine drive shaft (hereinafter referred to as the turbine shaft) 10 has a condensate storage tank 11
RCIC water supply pump (
(hereinafter referred to as a water supply pump) 12 is directly connected.

The RCIC configured in this way can be used to operate the reactor 2 in the event of an emergency such as a shutdown of reactor water supply in a nuclear power generation system.
is isolated, and as the reactor water level drops, the electric valve 4 begins to open, and the steam stop valve 5, which is already open and waiting,
The turbine 8 is activated by passing reactor steam through the steam control valve 7, which drives the water supply pump 12 to supply cooling water from the condensate storage tank 11 to the reactor 2 to cool the reactor core. It has this function. Since the water pump 12 must supply cooling water to the reactor 2 by securing a predetermined water supply amount, the turbine 8 must start as quickly as possible upon receiving the RCIC start signal and enter stable operation.

FIG. 3 shows a control device for the turbine 8. The control device includes a startup control section and a flow rate control section. The startup control section is for keeping the speed increase rate constant when the turbine 8 is started, and starts the ramp circuit 14 with the turbine startup command signal 13, and sets a ramp-shaped startup waiting target speed that increases at a predetermined slope with time. This is the part that generates the signal 15.

The flow rate control section is for controlling the discharge flow rate of the water supply pump 12 to be constant, and compares the water supply pump flow rate signal 16 and the water supply pump flow rate setting signal 18 from the water supply pump flow rate setting device 17 with a flow rate deviation calculator 19. The obtained flow rate deviation signal 20 is input to the flow rate controller 21 and the target speed signal 22 for flow rate control is inputted to the flow rate controller 21.
This is the part that makes it.

The startup waiting target speed signal 15 from the startup control section and the flow rate control target speed signal 22 from the flow rate control section are sent to a low value priority circuit 23.
is selected and becomes the target speed signal 24.

The target speed signal 24 is compared with a turbine speed signal 26 in a speed deviation calculator 25 to generate a turbine speed control signal 27, and the steam control valve 6 is operated by the turbine speed control signal 27 to control the turbine speed. The flow rate of the water supply pump 12 is controlled by.

When the turbine 8 is started, the water pump flow rate signal 16 is zero, so the flow rate control target speed signal 22 is larger than the start-up target speed signal 15, and the start-up target speed signal 15 is set as the target speed signal 24 by the low value priority circuit 23. Once selected, the target speed signal 24 ramps up in accordance with the standby target speed signal 15. As the target speed signal 24 increases, the turbine rotational speed increases and the water supply pump 12 starts supplying water, so that the target speed signal 22 for flow rate control becomes smaller than the start-up target speed signal 15, and the flow rate is determined as the target speed signal 24. The control target speed signal 22 is selected, and the speed of the turbine 8 is controlled so as to reach the flow rate set by the feedwater pump flow rate setting device 17.

(Problems to be Solved by the Invention) Due to its nature, RCIC can be used in a wide range of specified reactor pressures, and is required to ensure a specified flow rate within a specified time by rapid startup. ing.

The steam that drives the turbine 8 is the steam generated by the nuclear reactor 2, and the driving steam pressure is approximately equal to the reactor pressure. When the opening degree of the steam control valve 6 is the same, the driving energy of the turbine 8 becomes smaller as the driving steam pressure is lower, that is, as the reactor pressure is lower.

Therefore, the lower the reactor pressure, the lower the turbine speed side control signal 2.
The change in the drive energy of the turbine 8 with respect to the change in 7 is small, and the change in turbine speed is also small.

That is, the lower the reactor pressure is, the slower the response of the turbine speed to changes in the turbine speed control signal 27 becomes, and the longer it takes to reach a stable operating state in which a predetermined flow rate is ensured. This time becomes long, and if it exceeds a predetermined time, it will affect the safety of the nuclear reactor and is undesirable.

The present invention has been made in consideration of the above circumstances, and stabilizes the entire plant by shortening the time from rapid startup of the self-driven turbine to stable operation when the driving steam pressure is low. An object of the present invention is to provide a steam turbine control device that can achieve the following.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a steam turbine driven by steam supplied from a steam source via a steam control valve, by supplying cooling water to at least the steam source. A steam source to which the cooling water is supplied, in a steam turbine control device that is connected to a water supply pump and controls the speed of the steam turbine so that the target speed of the steam turbine increases according to a predetermined ramp function based on a turbine start command. The present invention is characterized in that it is provided with a pressure detector for detecting the pressure of the vehicle, and means for applying a bias signal to the target speed in accordance with the pressure detected by the pressure detector.

(Function) A circuit that calculates the target rotation speed based on the flow rate setting and furnace pressure is connected to the limiter of the flow rate control circuit, and this circuit switches from the startup lamp circuit to the water supply control circuit in the shortest possible time. . If the furnace pressure is below the rated value, the target rotation speed is set lower than the rated value, so the LVG at the start of PID control is
The input is lower than the target value and the necessary water supply cannot be secured.

The rotation speed deviation bias circuit applies a bias so that the rotation speed command value corresponds to the required water supply when the furnace pressure is below the rated value.

As a result, fluctuations in the feed water flow rate due to fluctuations in furnace pressure can be suppressed.

(Example) Next, an example in which the present invention is applied to the RCIC steam turbine pump system described above will be described in detail.

FIG. 1 shows an embodiment of the present invention.

Components that are the same as or correspond to those in FIG. 3 are given the same reference numerals, and their individual explanations will be omitted.

The difference between the devices shown in FIG. 1 and FIG. 3 is that the former is equipped with a pressure detector 28 that detects the pressure of the reactor 2 as a steam source, and a speed bias is applied according to the reactor pressure signal 29 obtained thereby. Speed bias signal 3 generated by generator 30
1 is added to the speed deviation calculator 25 as a bias signal for the target speed signal 24.

The speed bias generator 30 outputs a large speed bias signal 31 when the pressure of the nuclear reactor 2 is low, and outputs a small speed bias signal 31 when the pressure of the nuclear reactor 2 is high.

Assuming that the target speed signal 24 and the turbine speed signal 26 are the same when the pressure in the reactor 2 is low and high, and comparing the turbine speed control signal 27, it is found that the speed is higher when the pressure in the reactor 2 is low. Due to the large bias value, the turbine speed control signal 27 will also be large.

When the pressure in the reactor 2 is low, a large turbine speed control signal 27 is output to the steam control valve 6, which speeds up the response of the turbine speed and reaches a stable operating state where a predetermined flow rate is secured. The time taken can be shortened. In this way, the safety of the nuclear reactor 2 can be ensured.

Although the present invention has been described above in the case of controlling an RCIC turbine in nuclear reactor equipment, as already stated, the present invention can be generally applied to so-called self-driven steam turbines.

〔Effect of the invention〕

As described above, according to the present invention, steam turbine control is effective in achieving stabilization of the entire plant by shortening the time from turbine startup to stable operation when the driving steam pressure is low. equipment can be provided.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a system diagram of a reactor isolation cooling system in a nuclear power generation system, and Fig. 3 is a diagram of a turbine control device in a conventional reactor isolation cooling system. It is a block diagram. 2... Nuclear reactor, 6... Steam control valve 8...
- RCIC turbine, 12... RCIC water pump 19... flow deviation calculator, 25... speed deviation calculator 27... turbine speed control signal 28... pressure detector, 30... speed bias Generator agent Patent attorney Nori Chika Ken Yudo Hirofumi Mitsumata Figure 2 Figure 3

Claims (1)

[Claims] A water supply pump for supplying cooling water to at least the steam source is connected to a steam turbine driven by steam supplied from a steam source via a steam control valve, and the water supply pump is connected to a steam turbine driven by steam supplied from a steam source via a steam control valve, and the water pump is connected to a steam turbine driven by steam supplied from a steam source via a steam control valve. The steam turbine control device that controls the speed of the steam turbine so that the target speed of the steam turbine increases includes a pressure detector that detects the pressure of the steam source to which the cooling water is supplied, and a pressure detector that detects the pressure of the steam source to which the cooling water is supplied, and A steam turbine control device comprising means for applying a bias signal to a target speed.