JPH0241720B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an output control method and an output control device for a power plant, and is particularly suitable for application to a boiling water nuclear power plant (hereinafter simply referred to as a BWR power plant). The present invention relates to an output control method and an output control device for a power generation plant that can avoid unexpected nuclear reactor shutdown.

In a conventional BWR power plant, when the power system's frequency increase (or load demand decrease) exceeds a predetermined load setting bypass in the turbine controller, the turbine regulator is throttled and
The turbine bypass valve was open. in this case,
If the amount of throttling of the turbine control valve exceeded the installed capacity of the turbine bypass valve, the reactor could be shut down. That is, although the reactor output is constant and the amount of steam generated is also constant, the steam flow rate in the turbine system is decreasing, and due to this mismatch, the reactor pressure begins to rise. In a BWR power plant,
Since there is a positive power reactivity characteristic with respect to an increase in reactor pressure, the neutron flux within the reactor increases, and this increase in power further increases the reactor pressure. As a result, the reactor was scrammed (emergency shutdown) due to either a high reactor pressure or high neutron flux signal.

Next, the conventional turbine control device shown in FIG. 1 will be explained in more detail. Steam generated in the nuclear reactor 1 passes through a main steam pipe 2, passes through a main steam stop valve 3, a turbine control valve 4, and drives a high-pressure turbine 6. Since the low-pressure steam contains a lot of moisture, the quality of the steam is improved by the moisture separator 7, and then passes through the intermediate control valve 8, drives the low-pressure turbine 9, and is transferred to the condenser 10.
is returned to the water. On the other hand, a turbine bypass valve 5 is provided as a steam bypass system when the steam cannot be completely processed by the turbine. Water from the condenser 10 passes through a demineralizer and a condensate pump (not shown), reaches the feed water pump 11, passes through the feed water heater 12, and is supplied to the reactor 1. Steam extracted from the high-pressure turbine 6 is used as a heat source for the feedwater heater 12, and is supplied through an extraction pipe 28.

The turbine control valve 4 is connected to the output of the pressure controller 16.
It is controlled by the signal V 1 of P ₁ and the speed control system output S ₁ passed through the low value priority circuit ₁₈ , but since S ₁ is normally higher by the load setting bias B _L , pressure control is given priority.

Here, the pressure control system has a turbine inlet pressure of 15
In order to stably control the pressure 15 and its set value 1
The controller 16 controls the turbine inlet pressure deviation, which is the difference between
and obtain its control output P ₁ . On the other hand, the speed control system converts the deviation between the turbine speed 20 and its set rate 19 into a load variation using an amplifier 21 set to a predetermined speed regulation rate, and adds the load setting signal L _DS and bias B _L. and the signal _S1 is obtained. However, if f is the frequency increase of the power system and expressed as a percentage of the rated frequency, and the throttling of the turbine control valve 4, that is, the partial load and cut-off amount L is also expressed as a percentage of the rated load, both of them will have L. There is a relationship of =100×f/Rc. However, Rc is the speed adjustment rate (%)
The amplifier 21 is set to a value of 100/Rc.

In addition, a value corresponding to 10% load is normally selected for bias B _L , and S ₁ = P ₁ + 10 (%), so partial loads and failures within 10% rated load (speed increase is For L=Rc/10),
The turbine control valve 4 does not respond. However, when the load decreases by 10% or more, S ₁ < P ₁ and the turbine regulator valve 4 is closed, causing a difference between P ₁ and the actual turbine regulator opening V ₁ , and this difference (P ₁ −V ₁ ), the turbine bypass valve 5 is opened. Bias B ₁
is a small signal for stabilizing bypass valve operation.

By the way, assuming that the capacity of the bypass valve 5 is θ _B %, when a large partial load failure of θ _B +10% or more occurs, the turbine bypass valve 5 will not be able to process the steam completely, and as mentioned above, the atomic This will lead to the furnace shutting down. On the other hand, the intermediate control valve 8 is normally open and does not respond to the above-mentioned partial load failure, but it closes to prevent turbine acceleration when there is a large load failure such as a full load failure. As shown _in FIG _. ing. Therefore, it is the turbine control valve 4 and the turbine bypass valve 5 that respond to a partial load failure, and in the case of a load failure of θ _B +10% or more, the surplus steam cannot be processed. No,
Since the reactor will be shut down, it will take a long time to restart the reactor. Not only did it take a lot of energy to restart the plant, but the plant's operating rate was also decreasing.

The object of the invention described in claims 1 and 2 is to provide an output control method and an output control device for a power generation plant that can expand the area of partial load failure in which reactor scrams can be avoided. It is about providing.

An object of the invention as set forth in claim 3 is to provide an output control device for a power generation plant that can achieve the above-mentioned object of the invention and suppress a pressure rise in a moisture separator.

The feature of the invention described in claim 1 is that when a load reduction occurs, the opening degree of the intermediate control valve is controlled to reduce the output of the low pressure turbine, and when the load reduction exceeds a predetermined value, the output of the low pressure turbine is reduced. The purpose is to adjust the amount of load reduction that exceeds the value by controlling the openings of the turbine control valve and the bypass valve.

The invention as set forth in claim 2 is characterized by pressure control means for inputting the deviation between the measured steam pressure and the pressure setting value and outputting the first control signal, and for controlling the measured turbine speed and the speed setting. a speed control means for inputting a deviation from a value and outputting a second control signal; and a speed control means for selecting a control signal having a lower value from among the first control signal and the second control signal and outputting it to the turbine control valve. a value priority circuit; means for determining a deviation signal between the first control signal and the control signal output from the low value priority circuit and outputting it to the bypass valve; and means for outputting an intermediate control valve opening control signal based on the deviation of the control valve.

The feature of the invention described in claim 3 is, in addition to the feature of the invention described in claim 2,
The present invention includes means for controlling a bleed valve for adjusting the amount of steam introduced from the high-pressure turbine to the feed water heater based on the pressure of the steam introduced from the high-pressure turbine to the low-pressure turbine.

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 shows an embodiment of the BWR power plant output control device of the present invention. Similar to the conventional plant, the load request error signal 26 (δ _L ) is obtained from the pressure control system output P ₁ , the speed control system output S ₁ and the load setting bias _BL . That is, δ _L =P ₁ −S ₁ −B _L ...(1). This signal can be given to the reactor recirculation system that controls the reactor output, but the recirculation system is often operated manually due to thermal limitations of the fuel. In the present invention, this load request error signal 26 is passed through a variable limiter 101 and an amplifier 102, and then a bias _B10 is added thereto to generate a signal _V3 . Then, the conventional intermediate control valve request signal V ₂ and the new signal V ₃ are guided to the low value priority circuit 104, and the intermediate control valve 8 is controlled by the output signal.

On the other hand, when the intermediate control valve 8 is throttled, the pressure in the moisture separator 7 increases, and this is controlled by the bleed air control valve 108. That is, the high pressure turbine 6
The deviation between the signal 106 detecting the pressure of the steam exiting the system and the low pressure set value _PLS is guided to the pressure controller 107.
The bleed valve 108 is controlled by the control output.

Next, the operation will be explained. load setting bias
B _L is set to a value approximately equal to the turbine bypass capacity θ _B , and the gain G ₁₀₂ of the amplifier 103 is set to the following equation.

G ₁₀₂ =Q _L +Q _H /Q _L ...(2) Here, Q _L and Q _H are the low pressure turbine and high pressure turbine capacities, respectively. Also, bias B ₁₀ = 100%
Set to . The variable limiter 101 has a function of passing only a signal where -B _L ≦δ _L ≦0. During constant load operation, δ _L = 0 and V ₃ = 100%,
Since V ₂ >100%, the intermediate control valve 8 is fully opened, and in this state there is no difference from the prior art.

Next, if partial load shearing occurs and the shearing capacity L is within the bias B _L , the regulator valve 4 does not respond, and the load request error signal δ _L becomes -L, and the variable limiter 101 and the width increaser The signal V ₃ drops through the circuit 102 . That is, V ₃ =100−Q _H +Q _L /Q _L·L (3), and the intermediate control valve 8 is closed in accordance with the signal V ₃ . This reduces the low-pressure steam flow rate, thereby reducing the turbine output, but increasing the pressure in the moisture separator 7. However, since the bleed valve 108 is opened by the pressure controller 107, the pressure rise in the moisture separator 7 is suppressed, and the feed water temperature rises, causing the reactor coolant temperature to rise, due to the temperature reactivity effect. As a result, the reactor thermal output decreases. That is,
This control system allows the reactor output to follow the load.

Next, the load and breaking capacity exceeds _the bias B _L
When <L≦(B _L +θ _B ), a portion corresponding to the bias portion B _L is processed by the intermediate adjustment valve 7, and the bias amount is
When B _L is exceeded, control valve 4 closes and bypass valve 5
This operation is similar to the conventional example.

As described above, in this embodiment, when the load decreases, the intermediate control valve operates first, and then the turbine control valve and the turbine bypass valve operate. In the conventional example, when the load suddenly decreases, a pressure wave is generated in the main steam pipe due to the sudden closing of the regulator valve, causing a sudden pressure change in the reactor pressure, which causes There were cases where neutron flux increased rapidly and scrams with high neutron flux occurred. However, according to this embodiment, since the intermediate control valve operates in advance, the effect of causing pressure fluctuations on the main steam piping is extremely small, and the generation of pressure waves can be avoided.

According to this embodiment, since the opening degree adjustment of the intermediate control valve 8 is used for load following, the bias B _L can be increased to 25% to reduce the partial load cutting capacity up to the capacity of the conventional turbine bypass valve (usually 25%). Approximately by %
It can be increased up to 50%, and automatic frequency control, economical load distribution, etc. can be performed efficiently by fast load following operation.

In addition, in the conventional method, automatic load following control that directly connects the load request error signal to the reactor recirculation system is difficult due to thermal limitations of the fuel, but even if automatic load following operation is performed, the output Since fluctuations in are made by changing the reactor recirculation flow rate, there is a limit to its followability. According to this embodiment, the load request error signal can be guided to the reactor recirculation system, but when the recirculation system is manually operated, there is a load following ability with a quick response. In other words, since the load request error signal is used for intermediate control valve control, the turbine output rapidly follows changes in the load request, and on the reactor side, the feed water temperature changes through low pressure control, and the reactor output follows. . In other words, the capacity effect of the moisture separator and high-pressure turbine temporarily absorbs the mismatch between the reactor output and the turbine output, making it possible to take full advantage of the facility-saving advantages of a direct BWR plant. .

FIG. 3 shows another embodiment of the present invention,
The difference from FIG. 2 is that when the load is changed, the turbine bypass valve 5 is operated first, and then the intermediate control valve 8 is operated.
It controls the Although this embodiment has the same load following ability and pressure waves when the regulating valve suddenly closes as the conventional one, it is possible to increase the load shedding ability and is included in the scope of the present invention. That is, in FIG. 3, the operation signal of the turbine bypass valve 5 is subtracted from the bias B ₂ through the limiter 200 to obtain the request signal V ₂ of the intermediate control valve 8. The functions of this limiter 200 and bias B ₂ are to pass the bypass valve at a capacity θ _B or more, and to obtain the same gain (Q _L +Q _H /Q _H ) as the amplifier 102 of the embodiment shown in FIG.
When the turbine bypass valve 5 is fully opened in response to a load reduction, the intermediate control valve 8 is subsequently operated in the closing direction. Note that in this case, the bias B _L is set to approximately 10% load as in the conventional example.

As is clear from the above description, according to the inventions recited in claims 1 and 2, since the intermediate control valve is controlled in advance during partial load interruption, reactor scram can be avoided. It is possible to expand the area of partial load and rupture.

According to the invention recited in claim 3, it is possible to obtain the above-mentioned effects and to suppress an increase in the pressure of the moisture separator during partial loading or interruption.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional turbine control device, FIG. 2 is a block diagram showing one embodiment of the present invention, and FIG. 3 is a block diagram showing another embodiment of the present invention. 1... Nuclear reactor, 4... Turbine control valve, 5...
Bypass valve, 6... High pressure turbine, 7... Moisture separator, 8... Intermediate control valve, 9... Low pressure turbine,
10... Condenser, 12... Feed water heater, 16...
Pressure controller, 18...Low value priority circuit, 26...Load request error signal, 101...Variable limiter, 10
4...Low value priority circuit, 107...Pressure controller, 1
08...Bleed air adjustment valve, 200...Rimi.

Claims (1)

[Scope of Claims] 1. High-pressure and low-pressure turbines driven by steam generated in a nuclear reactor, a turbine control valve that adjusts the amount of steam supplied from the nuclear reactor to the high-pressure turbine, and a condenser for the generated steam A method for controlling the output of a power generation plant, comprising: a bypass valve that adjusts the amount of steam introduced into the low-pressure turbine; and an intermediate control valve that adjusts the amount of steam led from the high-pressure turbine to the low-pressure turbine. The output of the low-pressure turbine is reduced by controlling the opening degree of the intermediate control valve, and when the load reduction exceeds a predetermined value, the opening degree of the turbine control valve and the bypass valve is controlled to compensate for the load reduction exceeding the predetermined value. 1. A method for controlling the output of a power generation plant, characterized in that the output is adjusted by: 2. High-pressure and low-pressure turbines driven by steam generated in the nuclear reactor, a turbine control valve that adjusts the amount of steam supplied from the nuclear reactor to the high-pressure turbine, and adjusts the amount of bypass of the generated steam to the condenser. In a device for controlling the output of a power generation plant, the device is equipped with a bypass valve for controlling the amount of steam introduced from the high-pressure turbine to the low-pressure turbine, and an intermediate control valve for adjusting the amount of steam introduced from the high-pressure turbine to the low-pressure turbine. pressure control means for inputting a deviation between the measured turbine speed and the speed setting value and outputting a second control signal; A low value priority circuit selects the lowest value control signal from the two control signals and outputs it to the turbine control valve, and a deviation signal between the first control signal and the control signal output from the low value priority circuit is determined. and means for outputting an intermediate control valve opening control signal based on a deviation between the first control signal and the second control signal. Output control device. 3. High-pressure and low-pressure turbines driven by steam generated in the nuclear reactor, a turbine control valve that adjusts the amount of steam supplied from the nuclear reactor to the high-pressure turbine, and adjusts the amount of bypass of the generated steam to the condenser. In a device for controlling the output of a power generation plant, the device is equipped with a bypass valve for controlling the amount of steam introduced from the high-pressure turbine to the low-pressure turbine, and an intermediate control valve for adjusting the amount of steam introduced from the high-pressure turbine to the low-pressure turbine. pressure control means for inputting a deviation between the measured turbine speed and the speed setting value and outputting a second control signal; A low value priority circuit selects the lowest value control signal from the two control signals and outputs it to the turbine control valve, and a deviation signal between the first control signal and the control signal output from the low value priority circuit is determined. means for outputting the control signal to the bypass valve; means for outputting an intermediate control valve opening control signal based on the deviation between the first control signal and the second control signal; An output control device for a power generation plant, comprising means for controlling a bleed valve that adjusts the amount of steam based on the pressure of steam guided from the high pressure turbine to the low pressure turbine.