Nuclear power plant and output control device

Abstract

To obtain an operation plan having high operability including width and a period of adjustment force.SOLUTION: A nuclear power generation plant 100 includes a power generation system 101 and an output control device 102. The output control device includes: an evaluation criterion input device 28 for inputting a market price prediction value of wholesale power and a consumption adjustment; an adjustment force setting device 26 for setting an adjustment force supply amount for adjusting consumption from information on a price prediction value and a reactor core / plant state including a margin for a thermal restriction of at least a reactor core and a control rod position; an operation plan evaluation device 25 for generating an operation plan from an adjustment force supply amount and evaluation propriety of the plan; a dynamic characteristic evaluation system 24 for evaluating a reactor core / plant state on the basis of an operation plan; and an operation plan output device 27 for outputting an operation plan obtained by a repeated evaluation of the adjustment force setting device and the operation plan evaluation device.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a nuclear power plant and an output control device.

Background Art

[0002] Conventionally, there is a nuclear power plant that automatically generates an operation plan for bidding in the regulation power market during the operation of the plant.

[0003] In recent years, as the introduction of renewable energy has expanded, in addition to the conventional changes in demand, power transmission and distribution operators match the fluctuating power generation amount and power demand, including changes in the power generation amount of solar power generation and wind power generation, moment by moment. To do this, they perform various power source adjustments and power trading by power transmission.

[0004] To meet the electricity demand of a target region, it is necessary to adjust the amount of electricity generated to match the demand by mutually exchanging electricity with other regions. One type of adjustable power generation facility is hydroelectric power, including pumped-storage hydroelectric power. However, the amount of electricity generated by hydroelectric power plants is not large enough to compensate for the variability of renewable energy, so traditionally, thermal power plants have been mainly used for this adjustment. Thermal power plants can supply a stable amount of electricity and can change the amount of electricity generated relatively quickly. However, thermal power plants emit carbon dioxide. In recent years, as countries have been promoting measures toward carbon neutrality, the increase in CO2 emissions from thermal power plants is undesirable. Therefore, there is a need to compensate for the variability of electricity generated by renewable energy with nuclear power. Nuclear power plants have been used as base-load power sources until now, but countries such as France and Germany have experience in operating them to adjust the amount of electricity generated according to the load. Adjusting the amount of electricity generated by nuclear power plants is done by adjusting the output of the reactor, and this is done by controlling the insertion position of the control rods, the core flow rate, the boron concentration, etc. In particular, in boiling water reactors, two common methods for adjusting power output are controlling the coolant density in the core, which promotes neutron deceleration, by reducing the core flow rate, and controlling power output by inserting and removing control rods, which are neutron absorbers, into the core. When controlling power output with core flow rate, there is an operational limit between core thermal output and core flow rate to maintain fuel integrity, and it is necessary to avoid exceeding this limit. Furthermore, in order to maintain fuel integrity, the power distribution must be changed only within the range of the power distribution (envelope) obtained when the nuclear fuel was pre-run. For this reason, the use of power change patterns that have been confirmed to be operable offline in advance (for example, 14 hours of high-power constant operation, 8 hours of low-power operation, and 1 hour of power change) has been considered.

[0005] Patent Document 1 discloses a load-following operation method for a nuclear power plant that can achieve operation that closely matches actual electricity demand. This method comprises a core performance calculation and evaluation unit that inputs plant data such as core flow rate, core pressure, and neutron flux obtained from various measuring instruments placed in the reactor and calculates core state quantities such as current core thermal output and output distribution; an operation pattern estimation unit that estimates a load-following operation pattern based on the calculation results and requests from the operators; a prediction calculation unit that predicts core state changes when the plant is operated according to the previously estimated operation pattern; an operator's control panel equipped with an input unit for inputting requests from the operators and a display that shows the previous operation pattern and the previous prediction results. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 165690 / 1983 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In Japan, electricity liberalization was introduced in 2016, and the trading of generated electricity is shifting from bilateral contracts to market-based transactions. A system is being established in which supply and demand are adjusted through the market, and transmission and distribution companies procure electricity through the market to match electricity demand with generation. In addition to the wholesale electricity market where the amount of electricity is traded, there is also an adjustment capacity market where the amount of electricity that can be adjusted to match supply and demand is traded. Transmission and distribution companies procure the amount of electricity that can be increased or decreased at a given time through this market, and request an increase or decrease in generation when adjustment is actually needed. On the other hand, power generators can profit by providing adjustment capacity along with wholesale electricity according to market prices and receiving a selling price.

[0008] For example, consider a scenario where variable renewable energy sources (VREs) such as solar and wind power generate a large amount of electricity, causing wholesale electricity prices to drop to near zero in order to curb other power sources, while the cost of adjusting power (increasing output) becomes high. Under such conditions, profits can be maximized by operating the reactor to reduce output to the minimum output and maximize the adjustment power (increasing output). However, depending on the core state at the time, it may not be possible to increase output to the maximum output after reducing it to the minimum output. For example, if the insertion position of the control rods is adjusted to increase output, the output will partially increase within the core, and it may not be possible to increase output to the maximum output due to thermal limitations to ensure fuel integrity. Alternatively, the core flow rate may be controlled at the maximum (minimum) level, making it impossible to increase (decrease) output by adjusting the core flow rate.

[0009] These core and control states depend on past operating history, and it is necessary to evaluate feasible adjustment capabilities based on these constantly changing conditions and bid on them in the market. However, as mentioned above, such judgments must be made on a daily basis, and manual planning presents challenges such as requiring a large number of personnel or potentially harming profits due to the inability to make rapid evaluations.

[0010] On the other hand, nuclear power plants have limitations such as the aforementioned operating range and thermal limitations, which may prevent them from simply creating a standby state to maximize profits through output changes or adjustments.

[0011] The present invention has been made to solve the aforementioned problems, and its main objective is to provide a nuclear power plant and an output control device that can obtain a highly operational operating plan that includes a range and duration of adjustment capabilities. [Means for solving the problem]

[0012] To achieve the above objective, the present invention provides a nuclear power plant comprising a power generation system and an output control device, wherein the output control device includes an evaluation criterion input device for inputting predicted market prices for wholesale electricity and demand adjustment, an adjustment force setting device for setting the adjustment force supply amount for supply and demand adjustment from the price prediction values ​​and information on the core / plant state including at least a margin against the thermal limits of the core and the control rod positions, an operation plan evaluation device for generating an operation plan from the adjustment force supply amount and evaluating the feasibility of the plan, a dynamic characteristics evaluation system for evaluating the core / plant state based on the operation plan, and an operation plan output device for outputting an operation plan obtained by iterative evaluation between the adjustment force setting device and the operation plan evaluation device. Other methods will be described later. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a nuclear power plant and an output control device that can obtain a highly operational operating plan that includes a range and duration of adjustment capabilities. [Brief explanation of the drawing]

[0014] [Figure 1] This is an overall configuration diagram of a nuclear power plant according to Embodiment 1. [Figure 2] This is a flowchart showing the operation of a nuclear power plant according to Embodiment 1. [Figure 3] This is an explanatory diagram showing an example of the input screen of the evaluation criteria input device. [Figure 4A] This is a diagram (1) illustrating the method for setting the range and duration of the adjustment force in the adjustment force setting device. [Figure 4B] This is a diagram (2) illustrating the method for setting the range and duration of the adjustment force in the adjustment force setting device. [Figure 5A] This is an explanatory diagram of the operation plan created by the operation plan evaluation device. [Figure 5B] This is an explanatory diagram for the division of control rod groups. [Figure 5C] This is a diagram illustrating the procedure for operating control rods. [Figure 6]It is an explanatory diagram showing an example of an output screen of an operation plan output device. [Figure 7] It is an explanatory diagram of a dynamic characteristic evaluation system of a nuclear power plant according to Embodiment 2. [Figure 8] It is an overall configuration diagram of a nuclear power plant according to Embodiment 3. [Figure 9] It is an explanatory diagram of an operation plan selection device of a nuclear power plant according to Embodiment 3. [Figure 10] It is an overall configuration diagram of a nuclear power plant according to Embodiment 4.

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiments") will be described in detail with reference to the drawings. Note that each drawing only schematically shows the present invention to such an extent that it can be sufficiently understood. Therefore, the present invention is not limited only to the illustrated examples. In each drawing, common components and similar components are denoted by the same reference numerals, and redundant descriptions thereof are omitted.

[0016] [Embodiment 1] <Configuration of Nuclear Power Plant> Hereinafter, the configuration of a nuclear power plant 100 according to Embodiment 1 of the present embodiment will be described with reference to FIG. 1. FIG. 1 is an overall configuration diagram of the nuclear power plant 100 according to Embodiment 1 of the present embodiment.

[0017] As shown in FIG. 1, the nuclear power plant 100 according to Embodiment 1 of the present embodiment includes a power generation system 101 and an output control device 102. The output control device 102 outputs a control signal for performing output control by operating any one or a combination of a control rod, core flow rate, reactor pressure, feed water temperature, bypass valve opening degree, and reactor water boron concentration to the power generation system 101.

[0018] Inside the boiling water reactor pressure vessel 1, the reactor core 2 is held. Multiple control rods 3 (only one is shown in Figure 1) are attached to the reactor core 2 in a structure that allows them to be inserted and removed. The power generation system 101 is equipped with a control rod control device 4 that controls the control rods 3 to be in predetermined positions.

[0019] The reactor pressure vessel 1 is equipped with a recirculation pump 5 that sends the cooling water that has leaked out from the outlet of the core 2 back into the core 2, and the recirculation control device 6 controls it to maintain a predetermined core flow rate.

[0020] Furthermore, multiple neutron flux detectors 7 (only one is shown in Figure 1) are provided inside the reactor core 2, and the core power, power distribution, and margin against the thermal limits of the reactor core 2 are monitored by the power monitoring device 8. The margin against the thermal limits of the reactor core 2 includes one or more of the following: the maximum linear power density of the reactor core 2, the limiting power ratio or limiting heat flux ratio, axial offset, control rod position, core coolant flow rate, coolant temperature, and boron concentration.

[0021] The main steam that flows out of the reactor core in the reactor pressure vessel 1 passes through a control valve 10 whose opening is controlled by a pressure control device 9 and is sent to the high-pressure turbine 11. After passing through the high-pressure turbine 11, the main steam is dried and heated in a moisture separator heater 12 and then sent to the low-pressure turbine 13. Generators 14 are attached to the high-pressure turbine 11 and the low-pressure turbine 13, and the electricity generated by the rotation of the high-pressure turbine 11 and the low-pressure turbine 13 is sent to the grid.

[0022] The main steam that has passed through the low-pressure turbine 13 is condensed in the condenser 15. Steam that is sent directly to the condenser 15 from the bypass valve 16 without being sent to the high-pressure turbine 11 is also condensed in the condenser 15. The condensed water in the condenser 15 is returned to the reactor by the feedwater pump 17. At this time, the feedwater is heated by steam extracted from the main steam in the low-pressure feedwater heater 18 and the high-pressure feedwater heater 19, thereby improving the thermal efficiency of the turbine-condenser system.

[0023] Furthermore, in the example shown in Figure 1, the nuclear power plant 100 has an extraction valve 20 installed between the high-pressure turbine 11 and the high-pressure feedwater heater 19 to adjust the amount of steam extracted from the high-pressure turbine 11 to the high-pressure feedwater heater 19, and the feedwater temperature is controlled by a feedwater temperature control device 21. By changing the feedwater temperature, the nuclear power plant 100 can control the output of the reactor by changing the void ratio (volume ratio of contained steam) of the cooling water inside the reactor core 2.

[0024] The control rod control device 4, recirculation control device 6, output monitoring device 8, pressure control device 9, feedwater temperature control device 21, and generator output detector 22 attached to the generator are connected to the plant control device 23. The plant control device 23 controls the generator output of the nuclear power plant 100 using these devices.

[0025] The plant control device 23 is connected to a dynamic characteristics evaluation system 24 and an operation plan evaluation device 25. The moment-by-moment control status, core output, output distribution, and margin against the thermal limits of core 2 are sent to the dynamic characteristics evaluation system 24 and the operation plan evaluation device 25. Based on neutron dynamic characteristics calculations and thermohydraulic dynamic characteristics calculations, the dynamic characteristics evaluation system 24 outputs to the operation plan evaluation device 25 the core / plant state for the evaluation period obtained according to the initial core / plant state and the operation plan. Alternatively, as described in Embodiment 2 with reference to Figure 7, the dynamic characteristics evaluation system 24 may be trained using machine learning to obtain the core / plant state for the evaluation period obtained according to the initial core / plant state and the operation plan based on neutron dynamic characteristics calculations and thermohydraulic dynamic characteristics calculations, and then output to the operation plan evaluation device 25 the core / plant state for the evaluation period by inputting the initial core / plant state and the operation plan.

[0026] Furthermore, the operation plan evaluation device 25 is connected to the adjustment force setting device 26 and the operation plan output device 27, and the adjustment force setting device 26 is connected to the evaluation criterion input device 28.

[0027] <Operation of a nuclear power plant> The output control device 102 of the nuclear power plant 100 operates, for example, according to the flow shown in Figure 2. Figure 2 is a flowchart illustrating the operation of the nuclear power plant. Figure 2 shows the processing flow in the output control device 102 from the input of market prices to the output of the optimal operating plan.

[0028] As shown in Figure 2, when control of the nuclear power plant 100 is started, the output control device 102 first communicates with an external device (not shown) and inputs a predicted power price value consisting of the future wholesale power price and the adjustment power price of the adjustment power market from the external device to the evaluation criterion input device 28 (step S1).

[0029] The electricity price forecast value is sent from the evaluation criteria input device 28 to the adjustment power setting device 26. The adjustment power setting device 26 sets the period and width of the adjustment power to be supplied based on the electricity price forecast value, the current control status sent from the operation plan evaluation device, and the margin against the thermal limits of the reactor core 2 (step S2).

[0030] The set duration and width of the adjustment force are sent from the adjustment force setting device 26 to the operation plan evaluation device 25. The operation plan evaluation device 25 creates an operation plan that includes operations such as control rods and core flow rate to achieve the set duration and width of the adjustment force, following the same control algorithm as the plant control device 23 (step S3).

[0031] The created operating plan is input from the operating plan evaluation device 25 to the dynamic characteristics evaluation system 24. The dynamic characteristics evaluation system 24 calculates the control state of the reactor and the margin against the thermal limits of the core 2 when the operating plan is executed (step S4).

[0032] After this, the dynamic characteristics evaluation system 24 sends the calculation results to the operation plan evaluation device 25. Upon receiving the calculation results, the operation plan evaluation device 25 determines whether the control state and the margin for the thermal limits of the reactor core 2 are within an acceptable range (step S5).

[0033] If the determination in step S5 indicates that the control state and the margin for the thermal limits of core 2 are outside the acceptable range ("No"), the operation plan evaluation device 25 determines whether it is possible to modify the operation plan, such as changing the switching point between control rod operation and core flow rate operation or applying feedwater temperature control, within the range of the control algorithm incorporated in the plant control device 23 (step S6).

[0034] If the determination in step S6 indicates that the operation plan can be changed ("Yes"), the process returns to step S2. In this case, the operation plan evaluation device 25 implements the change and sends the change result to the dynamic characteristics evaluation system 24. The dynamic characteristics evaluation system 24 calculates the control state of the reactor and the margin against the thermal limits of the core 2 when the operation plan is executed, and sends the calculation result to the operation plan evaluation device 25.

[0035] If the determination in step S6 indicates that the operation plan cannot be changed ("No"), the process returns to step S3. In this case, the operation plan evaluation device 25 outputs to the adjustment force setting device 26 the operation plan, the period of adjustment force that can be supplied, the control state, and the maximum value of the deviation from the thermal limit for the set adjustment force range.

[0036] If the determination in step S5 indicates that the control state and the margin for the thermal limits of core 2 are within an acceptable range ("Yes"), the operation plan evaluation device 25 outputs the operation plan and the margin for the control state and the thermal limits of core 2 to the operation plan output device 27 (step S7).

[0037] In such a nuclear power plant 100, the power control device 102 and the adjustment power setting device 26 calculate the profit obtained from the operating plan based on the period during which adjustment power can be supplied (the margins for the control state and the thermal limits of the core 2 are within acceptable limits). The power control device 102 also reduces the range of adjustment power supplied based on the deviations from the control state and thermal limits in order to search for an operating plan that yields higher profits. At this time, the range of adjustment power is changed within a range that does not result in a profit smaller than the profit evaluated based on the feasible adjustment power range and period before the change and the electricity price forecast. Through such iterative evaluation of the adjustment power setting device 26, the operating plan evaluation device 25, and the dynamic characteristics evaluation system 24, the operating plan that ultimately maximizes profits is output to the operating plan output device 27. Such a power control device 102 can automatically generate the operating plan that yields the greatest profit among feasible operating plans based on the latest market price trends and the plant's core state and control state. As a result, the output control device 102 can quickly and efficiently control the power generation system 101 to obtain information on the range and duration of adjustment power necessary for bidding in the adjustment power market, without requiring a large number of personnel.

[0038] <Input screen of the evaluation criteria input device> The input screen of the evaluation criteria input device 28 will be described below with reference to Figure 3. Figure 3 is an explanatory diagram showing an example of the input screen of the evaluation criteria input device 28. In the example shown in Figure 1, the input screen of the evaluation criteria input device 28 is configured to include the "Forecast Value of Wholesale Electricity Price" field, the "Forecast Value of Adjustment Power Price" field, and the "Execute Evaluation" field.

[0039] The "Forecast Wholesale Electricity Price" field is where the forecast wholesale electricity price for a predetermined time interval (every 3 hours in Figure 3) is entered. The price forecast can also be read from a file, for example, in CSV format. The evaluation criteria input device 28 is equipped with a reading device such as flash memory for inputting files, or it can read file data by connecting to a network.

[0040] The "Predicted Adjustment Power Price" field will contain the predicted adjustment power price for a given time interval. The price predictions are entered using the same method as for wholesale electricity prices. However, two types of predicted adjustment power prices must be entered: one for increased output and one for decreased output.

[0041] The "Evaluation Execution" section includes a "Thermal Limitation" section, an "Output Control" section, an "Input Clear" button, and an "Evaluation Execution" button. The "Thermal Limitation" section is for specifying the thermal limiting elements to be used for output control. The "Output Control" section is for specifying the control elements to be used for output control. When the plant manager selects the thermal limiting elements in the "Thermal Limitation" section, selects the control elements in the "Output Control" section, and presses the "Evaluation Execution" button, the dynamic characteristics evaluation system 24 starts the evaluation.

[0042] <How to set the range and duration of adjustment> The method for setting the adjustment force range and duration in the adjustment force setting device 26 will be explained below with reference to Figures 4A and 4B. Figures 4A and 4B are explanatory diagrams of the method for setting the adjustment force range and duration in the adjustment force setting device 26.

[0043] (1) Figure 4A shows that the optimal supply amount (duration and width) of adjustment power at each time is set based on the wholesale electricity price and the adjustment power price. As shown in Figure 4A, first the adjustment power setting device 26 sets the initial width and duration of the adjustment power. At this time, initial values ​​are set at each time so that the total selling price of the electricity and adjustment power of the nuclear power plant 100 is maximized. At that time, the optimal supply amount of adjustment power at each time is set based on the wholesale electricity price and the adjustment power price. The adjustment power setting device 26 obtains the calculation result from the dynamic characteristics evaluation system 24 for this supply amount of adjustment power. Then, in determining the width of the adjustment power from the second time onward, the adjustment power setting device 26 calculates the profit that can be obtained in the operation plan based on the predicted values ​​of the wholesale electricity price and the adjustment power price during the period in which adjustment power can be supplied (when the margin for control state and thermal limits of core 2 is within the allowable value).

[0044] (2) Figure 4B shows that the width of the adjustment force is adjusted according to the deviation ratio with respect to the amount (duration and width) of the adjustment force supply. As shown in Figure 4B, the adjustment force setting device 26 then changes the width and duration of the adjustment force. At this time, the adjustment force setting device 26 reduces the width of the adjustment force according to the deviation ratio of the adjustment force duration, control state, and thermal limit value deviation. However, the reduction in the adjustment force is adjusted within a range where the profit is not less than the profit obtained in the previous iteration. For example, the adjustment force setting device 26 reduces the width of the adjustment force supplied according to the excess ratio to the control state and thermal limit in order to search for an operation plan that can obtain a higher profit. Then, after adjusting the width of the adjustment force, the adjustment force setting device 26 creates an operation plan with the operation plan evaluation device 25 and compares the profit obtained as a result of the operation plan with the previous value. In this way, the adjustment force setting device 26 repeats iterative evaluation with the operation plan evaluation device 25 until the adjustment force width that maximizes the profit is found.

[0045] <Training Plan> The following explanation of the operation plan created by the operation plan evaluation device 25 will be given with reference to Figure 5A. Figure 5A is an explanatory diagram of the operation plan created by the operation plan evaluation device 25.

[0046] In the example shown in Figure 5A, the horizontal axis represents time, the vertical axis represents generator output, the thick line represents core flow control, the thin line represents control rod control, and the dashed line represents the plan when adjustment force is implemented. The operation plan evaluation device 25 is created and updated to match the adjustment force set by the adjustment force setting device 26. In the example shown in Figure 5A, the plan is set to bid on the adjustment force market with a 50% increase in output from 6 hours to 12 hours after the start of the operation plan, and to provide power to the wholesale electricity market for the rest of the time. The operation plan evaluation device 25 incorporates an output control algorithm that performs core flow control from 100% to 70% when changing output, and controls rod control when changing output from 70% to 50%. In this embodiment, the output control algorithm incorporated inside the operation plan evaluation device 25 and the output control algorithm incorporated inside the plant control device 23 are assumed to be the same. The power generation system 101 will reduce its output by core reuse starting 5 hours after the start of the operation plan, and when the output reaches 70%, it will switch to reducing the output by inserting control rods.

[0047] <Control rod group division> The control rod group division will be explained below with reference to Figure 5B. Figure 5B is an explanatory diagram of the control rod group division. As shown in Figure 5B, in output adjustment using control rods, multiple control rods belonging to any control rod group are operated simultaneously (insertion or withdrawal operations are performed).

[0048] <Control rod operation procedure> The control rod operation procedure will be explained below with reference to Figure 5C. Figure 5C is an explanatory diagram of the control rod operation procedure. As shown in Figure 5C, the order of operation is predetermined, and the rods are inserted in this order when reducing the output. Six hours after the start of the operation plan, when the output has decreased to 50%, the system enters a standby state for supplying regulating force.

[0049] The numbers 1-30 in the horizontal row of Figure 5C indicate the procedure number. The values ​​Gr1-Gr8 in the vertical column indicate the control rod group (see Figure 5B). Incidentally, the left side of Figure 5B shows the grouping and arrangement of control rods Gr1-Gr5, and the right side of Figure 5B shows the grouping and arrangement of control rods Gr6-Gr8. The values ​​"32" and "4" in the two horizontal rows and two vertical columns of Figure 5C represent the withdrawal limit, which is the stopping position during continuous operation, and the number of steps during block operation (operating 4 steps at a time from steps 0 to 32), respectively. The control rod control device 4 operates the number of steps shown in Figure 5C in a single operation, based on the operation method command from the plant control device 23, i.e., the specification of continuous operation, block operation, or single-step operation. The values ​​in the columns other than the two horizontal rows and two vertical columns of Figure 5C are the same.

[0050] In the standby state for supplying adjustment power, the operation plan evaluation device 25 creates multiple operation plans to confirm that the specified adjustment power output increase can be achieved at any time. For example, the operation plan evaluation device 25 creates a total of eight operation plans: seven plans for supplying adjustment power with a 50% output increase every hour, such as after 6 hours and after 7 hours, and one plan for returning to the original 100% output without implementing adjustment power. Then, the dynamic characteristics evaluation system 24 sequentially performs dynamic characteristic calculations. The operation plan evaluation device 25 reads the control rod operating range and core flow rate change range as the control state for each case, and the most stringent value of the margin (or deviation) against the thermal limit of core 2 as the core state from the dynamic characteristics evaluation system 24. At this time, if the read control state and core state can be improved by applying a special control algorithm that is different from the usual one incorporated into the plant control device 23, and if there is a possibility that the adjustment power period can be increased, the operation plan evaluation device 25 recreates the operation plan using the special control algorithm.

[0051] The special control algorithm mentioned here is an algorithm that modifies the operating plan as follows: For example, if the core flow rate falls below the normal control range at high power after an increase in power output, the special control algorithm modifies the operating plan so that the recirculation flow rate is within the normal control range at high power output by manipulating (increasing) the recirculation flow rate within the power range where power output increases through control rod operation (withdrawal). Conversely, if the recirculation flow rate is higher than the normal control range at high power output after an increase in power output, the special control algorithm modifies the operating plan so that the recirculation flow rate at high power output is reduced to the normal control range by increasing power output through control rod (withdrawal) within the power range where power output increases through recirculation flow rate.

[0052] Furthermore, for example, if the vertical power distribution after power increase is biased towards the upper end, causing it to exceed the thermal limit in the upper range, the recirculation flow rate at high power levels can be reduced by controlling the feedwater temperature to lower the coolant temperature at the core inlet and increase power within the power range where power is increased by core flow. This shifts the vertical power distribution downwards, thus avoiding exceeding the thermal limit in the upper range. Additionally, if the core flow rate exceeds the control range when controlling power with core flow due to xenon effects, a control algorithm can be applied that temporarily controls the feedwater temperature to increase or decrease power, and then returns the feedwater temperature to its original value after the xenon effects have decreased over time.

[0053] <Output screen of the operation plan output device> The output screen of the operation plan output device 27 will be described below with reference to Figure 6. Figure 6 is an explanatory diagram showing an example of the output screen of the operation plan output device 27. In the example shown in Figure 6, the output screen of the operation plan output device 27 is configured to include the adjustment power supply amount for each operation plan in addition to the operation plan created by the operation plan evaluation device 25. By providing such an output screen to the plant manager, the output control device 102 allows the plant manager to immediately grasp the period for bidding in the adjustment power market and the range of adjustment power that can be supplied, enabling them to bid quickly. As a result, the output control device 102 can maximize profits and ensure a stable power supply. Furthermore, the output control device 102 reduces the workload of the plant manager in deciding whether to bid, allowing them to concentrate human resources on tasks such as ensuring safety.

[0054] Furthermore, in the example shown in Figure 6, a "Download" button (a button to send the operation plan) is displayed on the output screen. When the plant manager presses the "Download" button, the output control device 102 loads the operation plan created by the operation plan output device 27 into the plant control device 23, and the plant control device 23 can automatically operate the power generation system 101 according to the optimal operation plan.

[0055] <Main features of a nuclear power plant> (1) As shown in Figure 1, the nuclear power plant 100 according to this embodiment comprises a power generation system 101 and an output control device 102. The output control device 102 includes an evaluation criterion input device 28 for inputting predicted market prices for wholesale electricity and demand adjustment, an adjustment force setting device 26 for setting the adjustment force supply amount for supply and demand adjustment from the price prediction values ​​and information on the core / plant state including at least the margin for the thermal limits of the core 2 and the control rod positions, an operation plan evaluation device 25 for generating an operation plan from the adjustment force supply amount and evaluating the feasibility of the plan, a dynamic characteristics evaluation system 24 for evaluating the core / plant state based on the operation plan, and an operation plan output device 27 for outputting the operation plan obtained by iterative evaluation between the adjustment force setting device 26 and the operation plan evaluation device 25.

[0056] The nuclear power plant 100 according to this embodiment can, for example, automatically generate an operating plan that yields the greatest profit among feasible operating plans, based on the latest market price trends and the plant's core state and control state. As a result, the nuclear power plant 100 can obtain a highly operational operating plan that includes the range and duration of adjustment capacity necessary for bidding in the adjustment capacity market.

[0057] (2) In the nuclear power plant 100 according to this embodiment, the margin for the thermal limit of the core 2 includes one of the following of the maximum linear power density of the core 2, the critical power ratio or critical heat flux ratio, the axial offset, the control rod position, the core coolant flow rate, the coolant temperature, and the boron concentration, or a combination of these.

[0058] In this embodiment of the nuclear power plant 100, an operating plan can be created in which these items are treated as thermal limiting elements or control elements used for output control.

[0059] (3) In the nuclear power plant 100 according to this embodiment, the output control device 102 outputs a control signal to the power generation system 101 for controlling the output by operating one of the control rods, core flow rate, reactor pressure, feedwater temperature, bypass valve opening, and reactor water boron concentration, or a combination of these.

[0060] In this embodiment of the nuclear power plant 100, an operating plan can be created in which these items are treated as thermal limiting elements or control elements used for output control.

[0061] (4) As shown in Figure 1, in the nuclear power plant 100 according to this embodiment, the dynamic characteristics evaluation system 24 outputs the core and plant state for the evaluation period obtained according to the initial core and plant state and the operation plan to the operation plan evaluation device 25 based on neutron dynamic characteristics calculations and thermohydraulic dynamic characteristics calculations.

[0062] In this embodiment of the nuclear power plant 100, a suitable operating plan can be obtained because the range of adjustments in the operating plan can be repeatedly changed and evaluated between the dynamic characteristics evaluation system 24 and the operation plan evaluation device 25 in order to maximize profits.

[0063] As described above, the nuclear power plant 100 according to this embodiment 1 can provide a highly operational operating plan that includes the range and duration of adjustment capabilities. Furthermore, by submitting bids based on operational plans that take into account the latest market trends and plant conditions, it is possible to maximize profits and contribute to a stable power supply. Furthermore, it reduces the workload for plant managers in deciding whether to accept or reject bids, allowing them to concentrate human resources on tasks such as ensuring safety.

[0064] [Embodiment 2] In this second embodiment, we provide a nuclear power plant 100A (see Figure 7) that incorporates AI (Artificial Intelligence) functionality into the dynamic characteristics evaluation system 24 (see Figure 1) of the nuclear power plant 100 according to the first embodiment described above.

[0065] The configuration of the nuclear power plant 100A according to this second embodiment will be described below with reference to Figure 7. Figure 7 is an explanatory diagram of the dynamic characteristics evaluation system 24 of the nuclear power plant 100A according to this second embodiment.

[0066] As shown in Figure 7, the nuclear power plant 100A according to this second embodiment differs from the nuclear power plant 100 according to the first embodiment (see Figure 1) in that it is equipped with an output control device 102A instead of an output control device 102.

[0067] The output control device 102A of this embodiment 2 is a device in which an AI function (machine learning function) is incorporated into the dynamic characteristics evaluation system 24.

[0068] As shown in Figure 7, in this embodiment 2, the dynamic characteristics evaluation system 24 of the output control device 102A has an input layer 24a, an intermediate layer 24b, and an output layer 24c. In the example shown in Figure 7, the input layer 24a has a configuration with five input nodes, and each node receives input parameters for cycle burnup, initial core flow rate, initial control rod position, initial thermal limit margin, and the operation plan created by the operation plan evaluation device 25. The intermediate layer 24b has a configuration with three intermediate nodes. The output layer 24c has a configuration with four output nodes, and each node outputs output parameters for minimum thermal limit margin (deviation amount), maximum control rod withdrawal amount, core flow rate range, and period during which adjustment force can be supplied.

[0069] The dynamic characteristics evaluation system 24 of the output control device 102A calculates the dynamic characteristics by changing five parameters selected for the input node, and performs offline learning in advance using the results of the dynamic characteristics calculation. As a result, the dynamic characteristics evaluation system 24 of the output control device 102A can obtain results such as the period during which adjustment force can be supplied directly from the five input parameters without performing physical calculations, and the margin for thermal limitations.

[0070] The dynamic characteristics evaluation system 24 of the output control device 102A can be trained to learn the state of the reactor core and plant during the evaluation period, obtained according to the initial reactor core and plant state and the operation plan, based on, for example, neutron dynamic characteristics calculations and thermohydraulic dynamic characteristics calculations. The dynamic characteristics evaluation system 24 of the output control device 102A can then output the state of the reactor core and plant during the evaluation period to the operation plan evaluation device 25 by inputting the initial reactor core and plant state and the operation plan.

[0071] Because the output control device 102A of this embodiment 2 has a dynamic characteristics evaluation system 24 incorporating such AI functions, the response time of the dynamic characteristics evaluation system 24 can be shortened compared to the output control device 102 of the embodiment 1 described above, enabling rapid bidding in near real-time.

[0072] [Embodiment 3] In this second embodiment, a nuclear power plant 100B (see Figure 8) is provided that is equipped with an operation plan selection device 29 instead of a dynamic characteristics evaluation system 24 (see Figure 1) and an operation plan evaluation device 25 (see Figure 1).

[0073] The configuration of the nuclear power plant 100B according to this embodiment 3 will be described below with reference to Figures 8 and 9. Figure 8 is an overall configuration diagram of the nuclear power plant 100B according to this embodiment 3. Figure 9 is an explanatory diagram of the operation plan selection device 29 of the nuclear power plant 100B according to this embodiment 3.

[0074] As shown in Figure 8, the nuclear power plant 100B according to this third embodiment differs from the nuclear power plant 100 according to the first embodiment (see Figure 1) in that it is equipped with an output control device 102A instead of an output control device 102.

[0075] The output control device 102B of this third embodiment differs from the output control device 102 of the first embodiment described above in that it has an operation plan selection device 31 instead of the dynamic characteristics evaluation system 24 (see Figure 1) and the operation plan evaluation device 25 (see Figure 1).

[0076] The operation plan selection device 29 selects an operation plan pattern that satisfies the adjustment period required by the adjustment force setting device 26. The operation plan selection device 31 stores a large number of feasible operation plans that have been evaluated offline in advance. For example, the operation plan selection device 31 stores in advance multiple operation plan patterns that can ensure compliance with thermal limits and the achievement of a controlled state even under the most severe conditions imaginable for the initial core / plant state. The operation plan selection device 31 then selects an operation plan pattern from these patterns that satisfies the adjustment period required by the adjustment force setting device 26.

[0077] As shown in Figure 9, when the operation plan selection device 31 selects a pattern that satisfies the adjustment period requested by the adjustment power setting device 26, it outputs the selected pattern to the adjustment power setting device 26. In other words, the adjustment power setting device 26 obtains the operation plan stored in the operation plan selection device 29 from the operation plan selection device 29. The adjustment power setting device 26 also communicates with an external device (not shown) to obtain a predicted value of the electricity market price from the external device.

[0078] An output control device 102B having such an operation plan selection device 31 can automatically select an operation plan pattern that satisfies the adjustment period required by the adjustment power setting device 26, based on predicted values ​​of electricity market prices obtained from external equipment.

[0079] In addition, in other embodiments other than Embodiment 1 described above (for example, the nuclear power plant 100A according to Embodiment 2 shown in Figure 7), an operation plan selection device 31 may be provided instead of the dynamic characteristics evaluation system 24 and the operation plan evaluation device 25.

[0080] [Embodiment 4] In this fourth embodiment, a nuclear power plant 100C (see Figure 10) equipped with an electricity price forecasting device 30 is provided.

[0081] The configuration of the nuclear power plant 100C according to this embodiment 4 will be described below with reference to Figure 10. Figure 10 is an overall configuration diagram of the nuclear power plant 100C according to this embodiment 4.

[0082] As shown in Figure 10, the nuclear power plant 100C according to this embodiment 4 differs from the nuclear power plant 100 according to embodiment 1 (see Figure 1) in that it is equipped with an output control device 102C instead of an output control device 102.

[0083] The output control device 102C of this fourth embodiment differs from the output control device 102 of the first embodiment described above in that it has a power price prediction device 30.

[0084] The electricity price forecasting device 30 predicts the price of the electricity market, which was input externally in the nuclear power plant 100 (see Figure 1) according to the above-described embodiment 1, and inputs it to the evaluation criteria input device 28. The electricity price forecasting device 30 predicts the future price of the electricity market based on any or a combination of past price information of the electricity market, electricity demand information, operation / failure information of other power generation facilities, and weather information. The electricity price forecasting device 30 then outputs the predicted future price of the electricity market to the evaluation criteria input device 28.

[0085] The output control device 102C, which has such an electricity price forecasting device 30, can automatically acquire electricity market price forecasts based on the latest information at the time when it is necessary to evaluate the operation plan. Therefore, the output control device 102C can improve the accuracy of its forecasts compared to the output control device 102 of the embodiment 1 described above (see Figure 1).

[0086] In addition, the electricity price forecasting device 30 may also be provided in other embodiments other than Embodiment 1 (for example, the nuclear power plant 100A according to Embodiment 2 shown in Figure 7 and the nuclear power plant 100B according to Embodiment 3 shown in Figure 8).

[0087] The present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are described in detail for the purpose of clearly illustrating the present invention, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace some of the configurations of the embodiments with other configurations, and it is also possible to add other configurations to the configurations of the embodiments. In addition, it is possible to add, delete, or replace some of the configurations of each configuration with other configurations. [Explanation of Symbols]

[0088] 1. Reactor pressure vessel 2. Core 3 control rods 4. Control rod control device 5. Recirculation pump 6. Recirculation control device 7. Neutron Flux Detector 8. Output monitoring device 9. Pressure control device 10. Adjustment valve 11. High-pressure turbine 12 Moisture separation heater 13 Low-pressure turbine 14 Generators 15 Condenser 16 Bypass valve 17 Water supply pump 18. Low-pressure feedwater heater 19. High-pressure feedwater heater 20. Extraction valve 21 Water supply temperature control device 22 Generator output detector 23 Plant control system 24 Dynamic Characteristics Evaluation System 24a Input Layer 24b Middle class 24c output layer 25 Operation Plan Evaluation Device 26 Adjustment force setting device 27. Operation Plan Output Device 28 Evaluation Criteria Input Device 29. Operation Plan Selection Device 30 Electricity Price Prediction Device 100, 100A, 100B, 100C Nuclear Power Plant 101 Power Generation System 102, 102A, 102B, 102C Output control device

Claims

1. Power generation system and, It includes an output control device, The output control device is An evaluation criteria input device for inputting market price forecast values ​​for wholesale electricity and demand adjustment, A supply adjustment force setting device that sets the amount of adjustment force supplied for supply and demand adjustment based on price forecasts and information on the reactor core and plant conditions, including at least the margin against the thermal limits of the reactor core and the control rod positions, An operation plan evaluation device that generates an operation plan from the adjustment force supply amount and evaluates the feasibility of the plan, A dynamic characteristics evaluation system that evaluates the core and plant conditions based on the aforementioned operating plan, The system includes an operating plan output device that outputs an operating plan obtained by repeated evaluation between the adjustment force setting device and the operating plan evaluation device. A nuclear power plant characterized by the following features.

2. In the nuclear power plant according to claim 1, The margin against the thermal limits of the core includes one or more of the following: the maximum linear power density of the core, the critical power ratio or critical heat flux ratio, axial offset, control rod position, core coolant flow rate, coolant temperature, boron concentration. A nuclear power plant characterized by the following features.

3. In the nuclear power plant according to claim 1, The output control device outputs a control signal to the power generation system for controlling the output by manipulating one of the following: control rods, core flow rate, reactor pressure, feedwater temperature, bypass valve opening, and reactor water boron concentration, or a combination of these. A nuclear power plant characterized by the following features.

4. In the nuclear power plant according to claim 1, The dynamic characteristics evaluation system outputs to the operation plan evaluation device the initial core and plant conditions and the core and plant conditions during the evaluation period, obtained according to the operation plan, based on neutron dynamic characteristics calculations and thermohydraulic dynamic characteristics calculations. A nuclear power plant characterized by the following features.

5. In the nuclear power plant according to claim 1, The dynamic characteristics evaluation system uses machine learning to obtain the initial core and plant conditions and the core and plant conditions during the evaluation period, based on neutron dynamic characteristics calculations and thermohydraulic dynamic characteristics calculations, according to the operation plan. By inputting the initial core and plant conditions and the operation plan, the system outputs the core and plant conditions during the evaluation period to the operation plan evaluation device. A nuclear power plant characterized by the following features.

6. Power generation system and, It includes an output control device, The output control device is An evaluation criteria input device for inputting market price forecast values ​​for wholesale electricity and demand adjustment, A supply adjustment force setting device that sets the amount of adjustment force supplied for supply and demand adjustment based on price forecasts and information on the reactor core and plant conditions, including at least the margin against the thermal limits of the reactor core and the control rod positions, The system includes an operation plan selection device that stores multiple operation plan patterns in advance, which are capable of complying with thermal limits and achieving a controlled state even under the most severe conditions imaginable for the initial core and plant state, and selects a pattern from these patterns that satisfies the adjustment force period required by the adjustment force setting device. A nuclear power plant characterized by the following features.

7. In the nuclear power plant according to claim 1 or claim 6, The output control device is The device further comprises an electricity price forecasting device that predicts future electricity market prices based on any or a combination of past electricity market price information, electricity demand information, operation / failure information of other power generation facilities, and weather information, and outputs the prediction to the evaluation criteria input device. A nuclear power plant characterized by the following features.

8. An evaluation criteria input device for inputting market price forecast values ​​for wholesale electricity and demand adjustment, A supply adjustment force setting device that sets the amount of adjustment force supplied for supply and demand adjustment based on price forecasts and information on the reactor core and plant conditions, including at least the margin against the thermal limits of the reactor core and the control rod positions, An operation plan evaluation device that generates an operation plan from the adjustment force supply amount and evaluates the feasibility of the plan, A dynamic characteristics evaluation system that evaluates the core and plant conditions based on the aforementioned operating plan, The system includes an operating plan output device that outputs an operating plan obtained by repeated evaluation between the adjustment force setting device and the operating plan evaluation device. An output control device for a nuclear power plant, characterized by the following features.

9. In the output control device for a nuclear power plant according to claim 8, The device further comprises an electricity price forecasting device that predicts future electricity market prices based on any or a combination of past electricity market price information, electricity demand information, operation / failure information of other power generation facilities, and weather information, and outputs the prediction to the evaluation criteria input device. An output control device for a nuclear power plant, characterized by the following features.

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