Thermal storage power generation system and power generation control system

Abstract

To provide a heat storage power generation system and a power generation control system that can suitably operate a heat storage part and a power generation part.SOLUTION: A heat storage power generation system according to one embodiment comprises a heating part for heating a first heat transfer fluid. The system also comprises a heat storage part including a heat storage material to be heated by the first heat transfer fluid, and for heating a second heat transfer fluid by heat stored in the heat storage material. The system also comprises a power generation part for performing power generation by using the second heat transfer fluid. The system also comprises one or more temperature measuring instruments for measuring an internal temperature of the heat storage part. The system also comprises a power generation control part for controlling the power generation to be performed by the power generation part, on the basis of the internal temperature measured by the temperature measuring instruments.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a thermal storage power generation system and a power generation control system. [Background technology]

[0002] Various heat storage power generation systems have been proposed to date. Each heat storage power generation system includes a heat storage unit containing a heat storage material and a power generation unit that generates electricity using the heat stored in the heat storage material.

[0003] For example, there have been proposed techniques for controlling the temperature of the heat transfer fluid sent from the heat storage unit to the power generation unit, and for setting the gradient of the internal temperature distribution of the heat storage unit to a desired gradient. Furthermore, there has been proposed a technique for controlling the amount of energy used to heat the heat storage material to a constant value by measuring the temperature of the heat transfer fluid upstream of the inlet and downstream of the outlet of the heat storage unit when the heat storage unit is operated in heat release mode. There has also been proposed a technique for generating electricity using a steam turbine cycle in the power generation unit when the heat storage unit is operated in heat release mode.

[0004] In the heat storage mode, the heat storage material in the heat storage unit is heated by some means, for example, a high-temperature heat transfer fluid. The temperature of the heat storage material increases, and energy is stored in the heat storage unit. The high-temperature heat transfer fluid is produced, for example, by electricity generated using natural energy. This electricity is, for example, surplus electricity beyond the power required by the power grid.

[0005] In the heat release mode, the heat storage material in the heat storage section releases heat by some means, for example, to a low-temperature heat transfer fluid. The low-temperature heat transfer fluid receives thermal energy from the heat storage material and heats up. This reduces the thermal energy in the heat storage material. The heated heat transfer fluid in the heat storage section is sent to the power generation section, where it provides thermal energy to a steam turbine cycle. The power generation section uses this thermal energy to generate electricity. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] European Patent No. 3327399 [Patent Document 2] European Patent No. 3245467 [Patent Document 3] European Patent No. 3322955 Summary of the Invention [Problem to be solved by the invention]

[0007] However, these techniques are unable to control the operation of the power generation unit while taking into consideration the conditions inside the heat storage unit. It is believed that if the operation of the power generation unit is controlled while taking into consideration the conditions inside the heat storage unit, the heat storage unit and the power generation unit can be operated optimally.

[0008] Therefore, an embodiment of the present invention provides a heat storage power generation system and a power generation control system that can operate the heat storage unit and the power generation unit appropriately. [Means for solving the problem]

[0009] According to one embodiment, a thermal storage power generation system includes a heating unit that heats a first heat transfer fluid. The system further includes a heat storage unit that includes a heat storage material that is heated by the first heat transfer fluid and that heats a second heat transfer fluid using heat stored in the heat storage material. The system further includes a power generation unit that generates power using the second heat transfer fluid. The system further includes one or more temperature measuring devices that measure an internal temperature of the heat storage unit. The system further includes a power generation control unit that controls the power generation performed by the power generation unit based on the internal temperature measured by the temperature measuring devices. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing the configuration of a thermal storage power generation system according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the arrangement of temperature measuring devices in the first embodiment. [Figure 3] FIG. 4 is a schematic diagram for explaining the internal temperature Ts(xa, tk) of the heat storage unit of the first embodiment. [Figure 4] FIG. 4 is a schematic diagram for explaining the amount of thermal energy stored in the thermal storage unit Eg(tk) of the first embodiment. [Figure 5] FIG. 4 is a diagram for explaining the operation of the power generation planning processing unit of the first embodiment. [Figure 6] FIG. 4 is a diagram for explaining the relationship between input energy Q(tk) and generator output y(tk) of the power generation unit of the first embodiment. [Figure 7] FIG. 3 is a diagram for explaining an initial power generation plan according to the first embodiment. [Figure 8] FIG. 4 is a diagram for explaining energy calculations performed when formulating a modified power generation plan according to the first embodiment. [Figure 9] FIG. 4 is a diagram for explaining ΔEg(tk) in the first embodiment. [Figure 10] FIG. 10 is a diagram for explaining the generation of power plan formulation when ΔEg(tk)=0. [Figure 11] FIG. 10 is a diagram for explaining a modified power generation plan (2). [Figure 12] 10 is a flowchart showing the process for formulating a modified power generation plan (2). [Figure 13] FIG. 10 is a diagram showing the objective function and the like for formulating the modified power generation plan (3) by solving an optimization problem. [Figure 14] This is a flowchart showing the process for formulating the modified power generation plan (3) by solving an optimization problem. [Figure 15] FIG. 10 is a diagram for explaining the generation of power plan formulation when ΔEg(tk)<0. [Figure 16] FIG. 10 is another diagram for explaining the generation plan formulation when ΔEg(tk)<0. [Figure 17] FIG. 10 is a diagram for explaining the generation of power plan formulation when ΔEg(tk)>0. [Figure 18] FIG. 10 is another diagram for explaining the generation plan formulation when ΔEg(tk)>0. [Figure 19] 10 is a graph for explaining the interpolation process (linear interpolation) of the first modified example of the first embodiment. [Figure 20] 10 is a graph for explaining the interpolation process (spline interpolation) of the second modified example of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In Figures 1 to 20, the same components are denoted by the same reference numerals, and redundant description will be omitted.

[0012] (First embodiment) [A] Overall configuration FIG. 1 is a schematic diagram showing the configuration of a thermal storage power generation system according to the first embodiment.

[0013] The thermal storage power generation system of this embodiment includes a heating section 1, a thermal storage section 2, a power generation section 3, a first air blower section 4a, a second air blower section 4b, a power generation output measuring instrument 5, one or more temperature measuring instruments 6, a power generation planning processing section 7, a power generation control section 8, and an air blowing control section 9. The power generation output measuring instrument 5, the temperature measuring instrument 6, the power generation planning processing section 7, the power generation control section 8, and the air blowing control section 9 constitute a power generation control system that controls the thermal storage power generation system of this embodiment.

[0014] [A-1] Heating section 1 FIG. 1 shows an energy input 11 to a heating unit 1. The heating unit 1 of this embodiment receives electric power as the energy input 11 and converts the electric power into heat using a heat source such as an electric heater. The heating unit 1 of this embodiment further uses this heat to heat a low-temperature heat transfer fluid 12c to generate a high-temperature heat transfer fluid 12a. Note that the heating unit 1 may convert energy other than electric power into heat. The heat transfer fluids indicated by the reference symbols 12a, 12c, etc. are examples of a first heat transfer fluid.

[0015] The power generation control system of this embodiment includes a heating control unit (not shown) that controls the operation of the heating unit 1. The heating control unit controls the operation of the heating unit 1 so that, for example, the energy consumption of the heating unit 1 or the temperature of the heat transfer fluid 12a becomes a desired value.

[0016] [A-2] Heat storage section 2 The heat storage unit 2 contains a heat storage material (not shown) therein, and can store heat in the heat storage material. The heat storage material is, for example, crushed stone. The heat storage unit 2 of this embodiment is operated in a heat storage mode or a heat release mode.

[0017] In the heat storage mode, high-temperature heat transfer fluid 12a enters the heat storage unit 2. The heat storage material in the heat storage unit 2 is heated by the heat transfer fluid 12a. This causes the temperature of the heat storage material to rise. Meanwhile, the temperature of the heat transfer fluid 12a drops and becomes low-temperature heat transfer fluid 12b, which is discharged to the outside of the heat storage unit 2. In this way, in the heat storage mode, the temperature of the heat storage material in the heat storage unit 2 rises, and thermal energy is stored in the heat storage unit 2.

[0018] In the heat release mode, low-temperature heat transfer fluid 13a enters the heat storage unit 2. The heat of the heat storage material in the heat storage unit 2 is absorbed by the heat transfer fluid 13a, that is, the heat storage material releases heat to the heat transfer fluid 13a. This reduces the temperature of the heat storage material. Meanwhile, the temperature of the heat transfer fluid 13a rises and becomes high-temperature heat transfer fluid 13b, which is discharged to the outside of the heat storage unit 2. In this way, in the heat release mode, the heat storage material in the heat storage unit 2 releases thermal energy, thereby reducing the temperature of the heat storage material. The heat transfer fluids indicated by the symbols 13a, 13b, etc. are examples of second heat transfer fluids.

[0019] 1 as flowing from bottom to top within the heat storage unit 2, it does not necessarily flow from bottom to top in reality, and may flow, for example, from top to bottom, from right to left, or from left to right. Similarly, while FIG. 1 shows the heat transfer fluid 13a as flowing from top to bottom within the heat storage unit 2, it does not necessarily flow from top to bottom in reality, and may flow, for example, from bottom to top, from left to right, or from right to left. FIG. 1 schematically shows the flow directions of the heat transfer fluid 12a, the heat transfer fluid 13a, etc.

[0020] [A-3] Power Generation Unit 3 The power generation unit 3 generates electricity by utilizing the heat of the high-temperature heat transfer fluid 13b. The power generation unit 3 of this embodiment includes a steam turbine, a generator, a heat exchanger, a condenser, and the like, which form a steam turbine cycle. In this case, the power generation unit 3 generates steam from water using the heat of the heat transfer fluid 13b, drives a steam turbine using the steam, drives a generator using the steam turbine, and generates electricity using the generator. FIG. 1 shows the power generation output 14 from the power generation unit 3. Meanwhile, the temperature of the heat transfer fluid 13b decreases and becomes low-temperature heat transfer fluid 13c, which is discharged to the outside of the power generation unit 3. Note that the power generation unit 3 may generate electricity by utilizing the heat of the heat transfer fluid 13b in a manner other than the steam turbine cycle.

[0021] [A-4] First blower 4a and second blower 4b The first blower 4a is used to flow the heat transfer fluid 12b discharged from the heat storage unit 2 toward the heating unit 1. In FIG. 1, the heat transfer fluid flowing toward the first blower 4a is indicated by the symbol 12b, and the heat transfer fluid that has passed through the first blower 4a is indicated by the symbol 12c. The heat transfer fluid 12c enters the heating unit 1, is heated within the heating unit 1, and becomes high-temperature heat transfer fluid 12a, which is then discharged to the outside of the heating unit 1. In this way, the first blower 4a circulates the heat transfer fluids 12a, 12b, and 12c between the heating unit 1 and the heat storage unit 2.

[0022] The second blower 4b is used to send the heat transfer fluid 13c discharged from the power generation unit 3 to the heat storage unit 2. In FIG. 1, the heat transfer fluid flowing toward the second blower 4b is indicated by the reference symbol 13c, and the heat transfer fluid that has passed through the second blower 4b is indicated by the reference symbol 13a. The heat transfer fluid 13a enters the heat storage unit 2, is heated within the heat storage unit 2, and becomes high-temperature heat transfer fluid 13b, which is then discharged to the outside of the heat storage unit 2. In this way, the second blower 4b circulates the heat transfer fluids 13a, 13b, and 13c between the heat storage unit 2 and the power generation unit 3.

[0023] Depending on the operation purpose, the first blower 4a may either send a constant flow rate of heat transfer fluid 12c to the heating unit 1 or control the flow rate of heat transfer fluid 12c to match a fluctuating flow rate setting. Similarly, depending on the operation purpose, the second blower 4b may either send a constant flow rate of heat transfer fluid 13a to the heat storage unit 2 or control the flow rate of heat transfer fluid 13a to match a fluctuating flow rate setting. In either case, the operation of the first blower 4a and the second blower 4b is controlled by the blower control unit 9.

[0024] The heat storage power generation system of this embodiment may include a single air blower that blows heat transfer fluid 12c to heating unit 1 and heat transfer fluid 13a to heat storage unit 2, instead of including first air blower 4a that blows heat transfer fluid 12c to heating unit 1 and second air blower 4b that blows heat transfer fluid 13a to heat storage unit 2. In this case, this air blower may include a switching device that switches between an air blowing path for heat transfer fluid 12c and an air blowing path for heat transfer fluid 13a.

[0025] [A-5] Power Output Measuring Instrument 5 The power generation output measuring instrument 5 measures the power generation output 14 from the power generation unit 3 and outputs a power generation output measurement signal 15 indicating the measurement result of the power generation output 14. The measurement result of the power generation output 14 is, for example, the MW value of the power output from the power generation unit 3. In this embodiment, the power generation output measurement signal 15 is input to the power generation control unit 8.

[0026] [A-6] Temperature measuring instrument 6 Each temperature measuring device 6 measures the internal temperature of the heat storage unit 2 and outputs a temperature measurement signal 16 indicating the measurement result of the internal temperature. The internal temperature of the heat storage unit 2 is the temperature inside the heat storage unit 2. Each temperature measuring device 6 in this embodiment includes, for example, a temperature detection unit inserted into the heat storage material of the heat storage unit 2, and measures the temperature of the heat storage material itself or the temperature of the air or heat transfer fluid contained in the heat storage material as the internal temperature of the heat storage unit 2. The measurement result of the internal temperature is, for example, the internal temperature value measured by the heat storage unit 2. The temperature measurement signal 16 in this embodiment is input to the power generation planning processing unit 7. In FIG. 1, three temperature measurement signals 16 are input from three temperature measuring devices 6 to the power generation planning processing unit 7. It should be noted that the number of temperature measuring devices 6 in the thermal storage power generation system of this embodiment may be any number other than three.

[0027] The thermal storage power generation system of this embodiment further includes a temperature measuring device that measures the temperature of the heat transfer fluid 13a upstream of the inlet of the heat storage unit 2, and a temperature measuring device that measures the temperature of the heat transfer fluid 13b downstream of the outlet of the heat storage unit 2. The arrangement of these temperature measuring devices and the above-mentioned temperature measuring device 6 will be described in section [B] below. In this embodiment, these temperature measuring devices and the above-mentioned temperature measuring device 6 measure the temperature using thermocouples, but the temperature may also be measured using other methods (for example, infrared measurement method).

[0028] [A-7] Power generation planning processing section 7 The power generation plan processing unit 7 formulates a power generation plan for the power generation unit 3 based on the internal temperatures measured by each temperature measuring device 6. The power generation plan is a plan that indicates how power is to be generated by the power generation unit 3. The power generation plan, for example, specifies the MW value of the power to be output from the power generation unit 3 at each point in time in the future. In this case, the power generation plan includes, for example, time-series data of the MW value of the power to be output from the power generation unit 3. The thermal storage power generation system of this embodiment operates the power generation unit 3 in accordance with the power generation plan formulated by the power generation plan formulation unit 7.

[0029] The power generation plan processing unit 7 of this embodiment has the following functions, for example.

[0030] The power generation planning processing unit 7 uses the temperature measurement signals 16 received from each temperature measuring device 6 to determine a function that indicates the distribution of the internal temperature of the thermal storage unit 2. As will be described later, this function can be expressed as a function Ts(xa, tk) of location xa and time tk. The power generation planning processing unit 7 performs a calculation to determine the function Ts(xa, tk). In the following description, the function Ts(xa, tk) will also be referred to as "internal temperature Ts(xa, tk)" or "internal temperature distribution Ts(xa, tk)." In the function Ts(xa, tk), xa and tk may be abstractly represented as x and t.

[0031] The power generation plan processing unit 7 further calculates the amount of thermal energy Eg(tk) in the heat storage unit 2 that can be used for power generation from time tk to power generation end time tn in the heat release mode. This means that when the power generation unit 3 continues power generation from time tk to power generation end time tn, the power generation unit 3 can use the amount of energy Eg(tk) out of the total amount of energy in the heat storage unit 2 for power generation. Time tk is an example of a predetermined time. In this embodiment, the amount of energy Eg(tk) is calculated using the internal temperature distribution Ts(xa, tk), as will be described later. In the following description, the amount of energy Eg(tk) is also referred to as the "amount of available energy Eg(tk)" or the "amount of stored thermal energy Eg(tk)."

[0032] The power generation plan processing unit 7 further outputs, at time tk, one or more modified power generation plans 22, which are feasible power generation plans, using an initial power generation plan 21, which is an initial proposal for a power generation plan after time tk, the amount of stored thermal energy Eg(tk), and a power generation price signal 24. The power generation plan processing unit 7 may output a single modified power generation plan 22 at time tk, or may output multiple modified power generation plans 22 simultaneously. In the latter case, the power generation plan processing unit 7 selects one modified power generation plan 22 in response to an execution permission signal 23 that selects one from the multiple modified power generation plans 22, and determines this modified power generation plan 22 as an actual power generation plan 25 after time tk. On the other hand, in the former case, the power generation plan processing unit 7 determines the single modified power generation plan 22 as an actual power generation plan 25 after time tk. In this way, the power generation plan processing unit 7 determines the power generation plan to be executed.

[0033] The power generation plan processing unit 7 outputs a power generation command signal 17 at time tk based on this actual power generation plan 25. The power generation command signal 17 in this embodiment indicates a set value for the power generation output 14 from time tk onwards. This set value is determined in accordance with the actual power generation plan 25. The power generation command signal 17 is input to the power generation control unit 8.

[0034] The functions of the power generation plan processing unit 7 of this embodiment will be described in further detail in section [C] below.

[0035] [A-8] Power generation control unit 8 The power generation control unit 8 outputs a power generation control signal 18 to the power generation unit 3 so that the set value of the power generation output 14 indicated by the power generation command signal 17 matches the measured value of the power generation output 14 indicated by the power generation output measurement signal 15. For example, if the measured value is higher than the set value, the power generation control signal 18 is output to decrease the power generation output 14. On the other hand, if the measured value is lower than the set value, the power generation control signal 18 is output to increase the power generation output 14. In this way, the power generation control unit 8 controls the power generation performed by the power generation unit 3.

[0036] To control the power generation unit 3 in this way, the power generation control unit 8 measures various process variables, which are internal information of the power generation unit 3, and operates various control elements within the power generation unit 3 based on these process variables. Examples of process variables include the pressure, temperature, and flow rate of heat transfer fluid, steam, water, etc. Examples of control elements include valves and pumps. The power generation control unit 8 performs control to match the set value and measured value of the power generation output 14, for example, by PID (Proportional-Integral-Derivative) control.

[0037] [A-9] Air flow control unit 9 The air blowing control unit 9 controls the operation of the first air blowing unit 4a using a first air blowing control signal 19a, and controls the operation of the second air blowing unit 4b using a second air blowing control signal 19b. The air blowing control unit 9 can control the flow of heat transfer fluids 12a to 12c between the heating unit 1 and the heat storage unit 2 using the first air blowing control signal 19a, and can control the flow of heat transfer fluids 13a to 13c between the heat storage unit 2 and the power generation unit 3 using the second air blowing control signal 19b.

[0038] [B] Placement of temperature measuring instrument 6 FIG. 2 is a schematic diagram showing the arrangement of the temperature measuring devices 6 in the first embodiment.

[0039] FIG. 2 shows one or more temperature measuring devices 6 described above. Each temperature measuring device 6 measures the internal temperature of the heat storage unit 2 and outputs a temperature measurement signal 16 indicating the measurement result of the internal temperature to the power generation planning processing unit 7. FIG. 2 further includes a temperature measuring device 6a that measures the temperature of the heat transfer fluid 13a upstream of the inlet of the heat storage unit 2, and a temperature measuring device 6b that measures the temperature of the heat transfer fluid 13b downstream of the outlet of the heat storage unit 2. The temperature measuring devices 6a and 6b output temperature measurement signals 16a and 16b, respectively, indicating the measurement results of these temperatures to the power generation planning processing unit 7. The power generation control system of this embodiment further includes these temperature measuring devices 6a and 6b.

[0040] FIG. 2 shows the locations of the temperature measuring devices 6, 6a, and 6b. When the heat storage unit 2 shown in FIG. 2 is in the heat release mode, the low-temperature heat transfer fluid 13a enters the heat storage unit 2 from the left side, is heated by the heat storage unit 2, becomes the high-temperature heat transfer fluid 13b, and exits the heat storage unit 2 to the right side. In FIG. 2, the heat transfer fluid flowing through the heat storage unit 2 in the heat release mode is indicated by the reference symbol 13d. On the other hand, when the heat storage unit 2 shown in FIG. 2 is in the heat storage mode, the high-temperature heat transfer fluid 12a enters the heat storage unit 2 from the right side, is cooled by the heat storage unit 2, and becomes the low-temperature heat transfer fluid 12b, and exits the heat storage unit 2 to the left side. In FIG. 2, the heat transfer fluid flowing through the heat storage unit 2 in the heat storage mode is indicated by the reference symbol 12d.

[0041] The temperature measuring device 6 of this embodiment is used to measure the internal temperature of the heat storage unit 2 in the heat release mode. The internal temperature at one location in the heat storage unit 2 and the internal temperature at another location in the heat storage unit 2 will generally be different values ​​even at the same time. In other words, the internal temperature distribution in the heat storage unit 2 will generally be a non-uniform distribution. Furthermore, the temperature at each location in the heat storage unit 2 changes from moment to moment over time.

[0042] Therefore, in the thermal storage power generation system of this embodiment, it is desirable that the internal temperature of the thermal storage unit 2 is measured by a plurality of temperature measuring devices 6. In this way, by increasing the number of temperature measuring devices 6, it becomes possible to measure the internal temperature distribution in the thermal storage unit 2 with high precision. Furthermore, it is desirable that the calculation of term [C] described below is performed using a highly accurate internal temperature distribution Ts(xa, tk). Therefore, it is desirable that the thermal storage power generation system of this embodiment is provided with a large number of temperature measuring devices 6, for example, 20 to 100.

[0043] In Fig. 2, the plurality of temperature measuring devices 6 are arranged side by side along the flow direction of the heat transfer fluid 13d, i.e., side by side in the left-right direction. If the direction from left to right in Fig. 2 is the x direction, only one temperature measuring device 6 is arranged at each x coordinate.

[0044] However, these temperature measuring devices 6 may be arranged in a manner different from that shown in FIG. 2. For example, two or more temperature measuring devices 6 may be arranged at different locations on one x-coordinate. This makes it possible to measure not only a one-dimensional internal temperature distribution along the x-direction, but also a two-dimensional or three-dimensional internal temperature distribution. For example, if the two directions orthogonal to the x-direction are the y-direction and the z-direction, it is possible to measure a three-dimensional internal temperature distribution by arranging the plurality of temperature measuring devices 6 in a three-dimensional array along the x-direction, y-direction, and z-direction. The x-direction, y-direction, and z-direction are, for example, the horizontal, vertical, and depth directions within the heat storage unit 2.

[0045] The installation location of the temperature measuring device 6 in section [B] means the installation location of the temperature detection unit of the temperature measuring device 6. For example, when a certain temperature measuring device 6 detects the internal temperature of the heat storage unit 2 at the position of a certain terminal, the installation location of the temperature measuring device 6 means the position of that terminal. This also applies to the temperature measuring devices 6a and 6b.

[0046] [C] Function of the power generation planning processing unit 7 [C-1] Internal temperature Ts(xa, tk) FIG. 3 is a schematic diagram for explaining the internal temperature Ts(xa, tk) of the heat storage section 2 of the first embodiment.

[0047] FIG. 3(a) shows the distribution of the internal temperature of the heat storage unit 2 at the power generation start time (heat radiation start time) t1 in the heat radiation mode. The graph shown in the heat storage unit 2 shows the relationship between the horizontal location x within the heat storage unit 2 and the internal temperature T of the heat storage unit 2. FIG. 3(a) shows the internal temperature T at time t=t1 and location x=xa as Ts(xa, t1). FIG. 3(a) also shows the curve of the internal temperature Ts(xa, t1) as C1.

[0048] Similarly, Figure 3(b) shows the internal temperature distribution of the heat storage unit 2 at time tk in the heat radiation mode, and Figure 3(c) shows the internal temperature distribution of the heat storage unit 2 at the end time of power generation (heat radiation end time) tn in the heat radiation mode. Thus, Figures 3(a), 3(b), and 3(c) show the temporal change in the internal temperature of the heat storage unit 2 in the heat radiation mode. The subscripts 1, k, and n of times t1, tk, and tn are integers that satisfy the relationship 1≦k≦n. In Figures 3(b) and 3(c), the internal temperature T at time t=tk and location x=xa is represented as Ts(xa, tk), and the internal temperature T at time t=tn and location x=xa is represented as Ts(xa, tn). 3(b) and 3(c) further denote the curve of the internal temperature Ts(xa, tk) as Ck and the curve of the internal temperature Ts(xa, tn) as Cn.

[0049] For example, the power generation planning processor 7 receives internal temperatures at M locations in the thermal storage unit 2 at time tk from M temperature measuring devices 6 (M is an integer equal to or greater than 2). The power generation planning processor 7 can further apply interpolation to these internal temperatures to determine the internal temperature distribution Ts(xa, tk) at time t=tk. That is, the power generation planning processor 7 can determine a function (Ts(xa, tk)) indicating the distribution of the internal temperature of the thermal storage unit 2 as a function of the location xa and the time tk. This makes it possible to accurately grasp the internal temperature of the thermal storage unit 2. An example of such interpolation processing will be described later. Note that the power generation planning processor 7 may determine the internal temperature distribution Ts(xa, tk) at time t=tk without using interpolation.

[0050] When the heat storage unit 2 is operated in the heat dissipation mode, the internal temperature of the heat storage unit 2 decreases. As the internal temperature of the heat storage unit 2 decreases, the temperature of the heat transfer fluid 13b output from the heat storage unit 2 also decreases. When the temperature of the heat transfer fluid 13b output from the heat storage unit 2 falls below a certain value, the temperature of the heat transfer fluid 13b becomes unsuitable for power generation in the power generation unit 3. Time tn in this embodiment is the time immediately before the temperature of the heat transfer fluid 13b becomes unsuitable for power generation. The internal temperature distribution Ts(x, tn) at time tn can be determined in advance by analysis or test operation. Therefore, the power generation planning processing unit 7 in this embodiment stores the internal temperature distribution Ts(x, tn) at time tn in advance.

[0051] [C-2] Amount of stored heat energy Eg(tk) FIG. 4 is a schematic diagram for explaining the amount of thermal energy Eg(tk) stored in the thermal storage section 2 of the first embodiment.

[0052] FIG. 4(a) shows a curve C1 of the internal temperature distribution Ts(x,t1) at time t1, together with a curve Cn of the internal temperature distribution Ts(x,tn) at time tn. FIG. 4(a) also shows the integral Ag(t1) of the internal temperature difference Ts(x,t1)-Ts(x,tn) at time t1. The integral Ag(t1) corresponds to the area between the curve C1 and the curve Cn from the inlet location x0 of the thermal storage unit 2 to the outlet location xe of the thermal storage unit 2. The integral Ag(t1) is given by the following equation (1):

number

[0053] FIG. 4(b) shows the curve Ck of the internal temperature distribution Ts(x,tk) at time tk, together with the curve Cn of the internal temperature distribution Ts(x,tn) at time tn. FIG. 4(b) also shows the integral Ag(tk) of the internal temperature difference Ts(x,tk)-Ts(x,tn) at time tk. The integral Ag(tk) corresponds to the area between the curve Ck and the curve Cn from the inlet location x0 of the thermal storage unit 2 to the outlet location xe of the thermal storage unit 2. The integral Ag(tk) is given by the following equation (2):

number

[0054] Figure 4(c) shows the curve Cn of the internal temperature distribution Ts(x, tn) at time tn. The integral Ag(tn) of the internal temperature difference Ts(x, tn)-Ts(x, tn) at time tn is 0 (Ag(tn)=0).

[0055] Assume that the integral value Ag(t1) is calculated using equation (1) at time t1. If the heat capacity and mass of the heat storage material in the heat storage section 2 are Cpm [kJ / Kg / ℃] and W [kg], the amount of heat energy stored at time t1, Eg(t1), is given by the following equation (3).

number

[0056] Similarly, it is assumed that the integral value Ag(tk) is calculated at time tk using equation (2). In this case, the amount of stored thermal energy Eg(tk) at time tk is given by the following equation (4).

number

[0057] The amount of stored thermal energy Eg(tn) at time tn is 0 (Eg(tn)=0).

[0058] For example, at any time tk that satisfies t1≦tk≦tn, the power generation plan processing unit 7 can calculate the integral value Ag(tk) from the internal temperature distribution Ts(x,tn) using equation (2), and can calculate the amount of stored thermal energy Eg(tk) from the integral value Ag(tk) using equation (4). The thermal storage power generation system of this embodiment can extract the amount of energy Eg(tk) from the thermal storage unit 2 when the power generation unit 3 continues to generate power from time tk to time tn. The power generation plan processing unit 7 can further use the amount of stored thermal energy Eg(tk) to formulate a power generation plan for the time after time tk.

[0059] [C-3] Power Generation Plan FIG. 5 is a diagram for explaining the operation of the power generation plan processing unit 7 of the first embodiment.

[0060] 5 shows an initial power generation plan 21, a power generation price signal 24, and a plurality of temperature measurement signals 16 input to the power generation plan processing unit 7. FIG. 5 also shows one or more modified power generation plans 22, an execution permission signal 23, and an actual power generation plan 25. FIG. 5 shows the flow by which the power generation plan processing unit 7 formulates the actual power generation plan 25 from the initial power generation plan 21.

[0061] At time tk, the power generation plan processing unit 7 outputs one or more modified power generation plans 22, which are feasible power generation plans, using an initial power generation plan 21, which is an initial proposal for a power generation plan after time tk, the amount of thermal energy stored Eg(tk) calculated from the temperature measurement signal 16, and a power generation price signal 24 (step 1). At time tk, the power generation plan processing unit 7 may output a single modified power generation plan 22, or may output multiple modified power generation plans 22 simultaneously.

[0062] In the latter case, the power generation plan processing unit 7, for example, displays (proposes) a plurality of modified power generation plans 22 on a user interface and accepts a selection operation from the user to select one of the plurality of modified power generation plans 22. When the user inputs a selection operation on the user interface, an execution permission signal 23 is generated to select one of the plurality of modified power generation plans 22. The power generation plan processing unit 7 selects one modified power generation plan 22 in response to the execution permission signal 23 and determines this modified power generation plan 22 as the actual power generation plan 25 from time tk onwards. On the other hand, in the former case, the power generation plan processing unit 7 determines the single modified power generation plan 22 as the actual power generation plan 25 from time tk onwards. In this way, the power generation plan processing unit 7 determines the power generation plan to be executed (step 2).

[0063] The flow shown in FIG. 5 will now be described in further detail.

[0064] FIG. 6 is a diagram for explaining the relationship between input energy Q(tk) and generator output y(tk) of the power generating unit 3 in the first embodiment.

[0065] The graph in Figure 6 shows that the power generation efficiency η can be expressed as a function of the generator output y. This means that once the generator output y(k) is determined, the power generation efficiency η(tk) can be determined accordingly. This relationship can be expressed using the function g as in the following equation (5).

number

[0066] In this embodiment, y corresponds to the power generation output 14 from the power generation unit 3, and η corresponds to the power generation efficiency of the power generation unit 3.

[0067] On the other hand, if the amount of energy given to the power generation unit 3 at time tk is Q(tk), the relationship of the following equation (6) holds between Q(tk), y(tk), and η(tk).

number

[0068] Equation (6) corresponds to the definition of the power generation efficiency η. In equation (6), if the units of y(tk) are [MW] and Q(tk) are [MW], then 0≦η(tk)<1 holds. Here, η(tk)=1 means that all heat given to the power generation unit 3 is converted into electricity, which is prohibited by the second law of thermodynamics.

[0069] Now, suppose that a desired generator output ya(tk) at time tk is given. In this case, the energy Qa(tk) that needs to be provided to the power generation unit 3 is given by the following equation (7) from equations (5) and (6).

number

[0070] Since equation (7) expresses Qa(tk) as the ratio between ya(tk) and g(ya(tk)), it indicates that Qa(tk) can be calculated from ya(tk).

[0071] Therefore, the thermal storage power generation system of this embodiment includes a means for calculating η(tk) and Qa(tk) from ya(tk) when the value of the desired generator output ya(tk) is input. This means is provided in the power generation plan processing unit 7, for example.

[0072] FIG. 7 is a diagram for explaining the initial power generation plan 21 of the first embodiment.

[0073] The initial power generation plan 21 of this embodiment is input from outside the power generation plan processing unit 7 into the power generation plan processing unit 7. The initial power generation plan 21 can be expressed as a numerical sequence including a plurality of times t(k + 1), t(k + 2), …, tm after time tk and the desired generator outputs ya(t(k + 1)), ya(t(k + 2)), …, ya(tm) at these times (m is an integer satisfying k < m ≦ n).

[0074] In the example of FIG. 7, t(k + 1) = 0.5 [hours], t(k + 2) = 1 [hours], …, tm = 5 [hours], and ya(t(k + 1)) = 90 [MW], ya(t(k + 2)) = 85 [MW], …, ya(tm) = 75 [MW]. The initial power generation plan 21 in this example includes a power generation plan for 5 hours from time tk.

[0075] FIG. 8 is a diagram for explaining the energy calculation performed when formulating the modified power generation plan 22 of the first embodiment.

[0076] The power generation plan processing unit 7 calculates the necessary energies Qa(t(k + 1)), Qa(t(k + 2)), …, Qa(tm) at times t(k + 1), t(k + 2), …, tm using the initial power generation plan 21 and equation (7). The power generation plan processing unit 7 further calculates the total value Ea(tk) of the energy required to obtain the generator outputs ya(t(k + 1)), ya(t(k + 2)), …, ya(tm) of the initial power generation plan 21 by the following equation (8).

Equation

[0077] The total energy value Ea(tk) corresponds to the total value of the energy required for power generation by the power generation unit 3 until time tm. The above-mentioned heat storage energy amount Eg(tk) represents the energy available for power generation until the power generation end time tn, while the total energy value Ea(tk) represents the energy required for power generation until time tm. Hereinafter, the total energy value Ea(tk) is also referred to as the "required energy amount Ea(tk)".

[0078] The power generation plan processing unit 7 further calculates the difference ΔEg(tk) between the amount of thermal energy stored Eg(tk) and the amount of required energy Ea(tk) as shown in the following equation (9).

number

[0079] FIG. 9 is a diagram for explaining ΔEg(tk) in the first embodiment.

[0080] The power generation plan processing unit 7 of this embodiment formulates one or more modified power generation plans 22 taking ΔEg(tk) into consideration. These modified power generation plans 22 are proposed to the user on, for example, a user interface. In this case, the user can select a desired plan from these modified power generation plans 22.

[0081] Specifically, as shown in Fig. 9, the power generation plan processing unit 7 classifies the cases into a case where ΔEg(tk)=0, a case where ΔEg(tk)<0, and a case where ΔEg(tk)>0, and executes different processing depending on the case. Details of these processing will be explained below.

[0082] [C-3-1] When ΔEg(tk)=0 FIG. 10 is a diagram for explaining the generation of power plan formulation when ΔEg(tk)=0.

[0083] When ΔEg(tk)=0, the amount of stored thermal energy Eg(tk) matches the amount of required energy Ea(tk). In this case, the power generation plan processing unit 7 outputs modified power generation plan (1), modified power generation plan (2), and modified power generation plan (3) as modified power generation plans 22. As shown in FIG. 10, these plans are also referred to as proposed plan (1), proposed plan (2), and proposed plan (3), respectively.

[0084] <Modified Power Generation Plan (1)> The power generation plan processing unit 7 does not modify the initial power generation plan 21, and outputs the initial power generation plan 21 as modified power generation plan (1). Therefore, like the initial power generation plan 21, the modified power generation plan (1) includes generator outputs ya(t(k+1)), ya(t(k+2)), ..., ya(tm) at times t(k+1), t(k+2), ..., tm. The generator outputs are also referred to as "power generation amount."

[0085] <Modified Power Generation Plan (2)> The power generation plan processing unit 7 formulates a modified power generation plan (2) from the initial power generation plan 21 by modifying the initial power generation plan 21 using the power generation price signal 24. As shown in FIG. 10, the power generation price signal 24 indicates the power generation price p at times t(k+1), t(k+2), ..., tm. The power generation plan processing unit 7 formulates the modified power generation plan (2) so as to maximize the profit from power generation while utilizing as much stored thermal energy (available energy) Eg(tk) as possible. For example, if the power generation price is high in the first half of the time period from t(k+1) to tm and low in the second half of the time period from t(k+1) to tm, the power generation plan processing unit 7 increases the generator output in the first half of the time period from t(k+1) to tm and decreases the generator output in the second half of the time period from t(k+1) to tm. The modified power generation plan (2) shown in Figure 10 includes generator outputs yb(t(k+1)), yb(t(k+2)), ..., yb(tm) at times t(k+1), t(k+2), ..., tm.

[0086] FIG. 11 is a diagram for explaining the modified power generation plan (2).

[0087] 11 shows details of the initial power generation plan 21 and the modified power generation plan (2), as well as details of the power generation price signal 24. The power generation price signal 24 includes power generation prices p(t(k+1)), p(t(k+2)), ..., p(tm) at times t(k+1), t(k+2), ..., tm.

[0088] As described above, the power generation plan processing unit 7 formulates the modified power generation plan (2) from the initial power generation plan 21 by modifying the initial power generation plan 21 using the power generation price signal 24. Therefore, the value of the power generation amount yb in the modified power generation plan (2) has changed from the value of the power generation amount ya in the initial power generation plan 21. FIG. 11 shows the modified power generation plan (2) obtained under the constraints that the power generation upper limit value is 100 MW, the power generation lower limit value is 30 MW, and the power generation change rate is -20 MW / 0.5 hours to +20 MW / 0.5 hours.

[0089] FIG. 12 is a flowchart showing the process of formulating the modified power generation plan (2).

[0090] First, set the initial power generation plan 21 as y(t) = ya(t) (step S11). Next, calculate the average value yam of ya and the average value yzm of the power generation upper limit value and the power generation lower limit value (step S12). Next, calculate the generator outputs yb(tp) and yb(t(p + 1)) at the times tp and t(p + 1) when the power generation price p changes (step S13).

[0091] Next, when yam ≥ yzm (step S14 YES), determine the generator output yb for the remaining times by the first method (step S15). In the first method, for each generator output yb before the time tp, take the smaller of yb(tp) + 20 and the power generation upper limit value, and for each generator output yb after the time t(p + 1), make it an equal division of the remaining energy.

[0092] On the other hand, when yam < yzm (step S14 NO), determine the generator output yb for the remaining times by the second method (step S16). In the second method, for each generator output yb after the time t(p + 1), take the larger of yb(tp) - 20 and the power generation lower limit value, and for each generator output yb before the time tp, make it an equal division of the remaining energy.

[0093] <Modified power generation plan (3)> The power generation plan processing unit 7 modifies the initial power generation plan 21 by solving an optimization problem using the amount of thermal energy stored Eg(tk), and formulates a modified power generation plan (3) from the initial power generation plan 21. Specifically, the modified power generation plan (3) is calculated by formulating it as an optimization problem and solving it through the following process. The modified power generation plan (3) shown in FIG. 10 includes generator outputs yc(t(k+1)), yc(t(k+2)), ..., yc(tm) at times t(k+1), t(k+2), ..., tm.

[0094] Fig. 13 is a diagram showing the objective function and other information used to formulate the modified power generation plan (3) by solving an optimization problem. Fig. 13 shows one objective function, three constraints, and two model formulas used in the optimization problem.

[0095] The objective function J shown in Fig. 13 is used to maximize the electricity selling price. The power generation plan processing unit 7 performs calculations to maximize the objective function J in this optimization problem. In this case, an optimal solution to this optimization problem can be obtained by performing the iterative calculations shown in Fig. 14 within a range that does not deviate from the above three constraints.

[0096] The first constraint condition indicates a condition that the generator output y is varied between an upper limit value ymax and a lower limit value ymin. The second constraint condition indicates a condition that the rate of change dy / dt of the generator output is varied between an upper limit value dymax and a lower limit value dymin. The third conditional expression indicates a condition that the energy E used for power generation by the power generation unit 3 is equal to or less than the amount of thermal energy stored Eg. The first model expression indicates a relational expression related to the power generation efficiency η. The second model expression indicates a relational expression related to the energy E.

[0097] FIG. 14 is a flowchart showing the process of formulating the modified power generation plan (3) by solving an optimization problem.

[0098] First, set the initial power generation plan 21 with y(t) = ya(t) (step S21). Next, determine whether the number of calculation times N has reached the upper limit (step S22). If the determination in step S22 is YES, since the desired power generation plan cannot be achieved, an error message prompting the reset of ya(t) is output (step S23).

[0099] On the other hand, if the determination in step S22 is NO, perform a simulation calculation for time t0 to tn using the above two model equations to calculate the energy E (step S24). Next, determine whether y(t), dy(t) / dt, and E calculated in steps S21 to S24 satisfy the above three constraint conditions (step S25).

[0100] If the determination in step S25 is YES, determine whether J(N) - J(N - 1) < eps is satisfied (step S26). Here, J(N) represents the objective function J calculated at the Nth time. If the determination in step S26 is YES, output the modified power generation plan (3) by setting y(t) calculated using J(N) as yc(t) (step S27). On the other hand, if the determination in step S25 or S26 is NO, correct y(t) (step S28) and return to step S22.

[0101] [C - 3 - 2] When ΔEg(tk) < 0 FIG. 15 is a diagram for explaining the determination of the power generation plan when ΔEg(tk) < 0.

[0102] When ΔEg(tk) < 0, the amount of heat storage energy Eg(tk) is insufficient with respect to the required energy amount Ea(tk). In this case, the power generation plan processing unit 7 outputs the modified power generation plan 22, which includes the modified power generation plan (1), the modified power generation plan (2), the modified power generation plan (3), and the modified power generation plan (4). As shown in FIG. 15, these plans are also denoted as plan proposal (1), plan proposal (2), plan proposal (3), and plan proposal (4), respectively.

[0103] <Modified Power Generation Plan (1)> The power generation plan processing unit 7 modifies the modified power generation plan (1) by uniformly reducing all generator outputs ya in the initial power generation plan 21, and formulates the modified power generation plan (1) from the initial power generation plan 21. The modified power generation plan (1) shown in Fig. 15 includes generator outputs ya'(t(k+1)), ya'(t(k+2)), ..., ya'(tm) at times t(k+1), t(k+2), ..., tm.

[0104] For example, if the initial power generation plan 21 includes ten generator outputs ya(0.5), ya(1), ya(1.5), ..., ya(5) at ten times t = 0.5, 1, 1.5, ..., 5, each generator output ya'(t) of the modified power generation plan (1) is given by the following equation (10).

number

[0105] Therefore, ya'(0.5), ya'(1), ya'(1.5), ..., ya'(5) are the sums of ya(0.5), ya(1), ya(1.5), ..., ya(5) and ΔEg(tk) / 10, respectively. Note that, since ΔEg(tk) in the case of FIG. 15 is negative, ya'(0.5), ya'(1), ya'(1.5), ..., ya'(5) are smaller than ya(0.5), ya(1), ya(1.5), ..., ya(5), respectively. This makes it possible to reduce the total power generation amount ya'(t(k+1))+ya'(t(k+2)), ..., +ya'(tm) of the modified power generation plan (1) below the total power generation amount ya(t(k+1))+ya(t(k+2)), ..., +ya(tm) of the initial power generation plan 21.

[0106] <Modified Power Generation Plan (2)> The power generation plan processing unit 7 formulates a modified power generation plan (2) from the initial power generation plan 21 by modifying the initial power generation plan 21 using the power generation price signal 24. The modified power generation plan (2) shown in Fig. 15 includes power generator outputs yb(t(k+1)), yb(t(k+2)), ..., yb(tm) at times t(k+1), t(k+2), ..., tm.

[0107] The modified power generation plan (2) when ΔEg(tk)<0 can be calculated in the same way as the modified power generation plan (2) when ΔEg(tk)=0. However, the modified power generation plan (2) when ΔEg(tk)<0 is calculated so as to satisfy the constraint that the required energy amount E(tk) (=Ec(tk)) calculated using equations (7) and (8) matches the stored thermal energy amount Eg(tk). This constraint is expressed by the following equation (11).

number

[0108] For example, if the power generation price is high in the first half of the time period t(k+1) to tm and low in the second half of the time period t(k+1) to tm (see FIG. 15), the generator output in the first half of the time period t(k+1) to tm is not changed, and the generator output in the second half of the time period t(k+1) to tm is reduced. This makes it possible to reduce the total power generation amount yb(t(k+1))+yb(t(k+2)), ..., +yb(tm) of the modified power generation plan (2) below the total power generation amount ya(t(k+1))+ya(t(k+2)), ..., +ya(tm) of the initial power generation plan 21.

[0109] <Modified Power Generation Plan (3)> The power generation plan processing unit 7 modifies the initial power generation plan 21 by solving an optimization problem using the amount of thermal energy stored Eg(tk), and formulates a modified power generation plan (3) from the initial power generation plan 21. The modified power generation plan (3) shown in Fig. 15 includes generator outputs yc(t(k+1)), yc(t(k+2)), ..., yc(tm) at times t(k+1), t(k+2), ..., tm.

[0110] The modified power generation plan (3) when ΔEg(tk)<0 can be calculated in the same way as the modified power generation plan (3) when ΔEg(tk)=0. This makes it possible to reduce the total power generation amount yc(t(k+1))+yc(t(k+2)), ..., +yc(tm) of the modified power generation plan (3) below the total power generation amount ya(t(k+1))+ya(t(k+2)), ..., +ya(tm) of the initial power generation plan 21.

[0111] <Modified Power Generation Plan (4)> The power generation plan processing unit 7 formulates a modified power generation plan (4) from the initial power generation plan 21 by modifying the initial power generation plan 21 so as to stop power generation at times when the power generation price p is low. The modified power generation plan (4) shown in Fig. 15 includes power generator outputs yd(t(k+1)), yd(t(k+2)), ..., yd(tm) at times t(k+1), t(k+2), ..., tm.

[0112] Details of the modified power generation plan (4) are shown in FIG. 16. FIG. 16 is another diagram for explaining the formulation of a power generation plan when ΔEg(tk)<0. In FIG. 16, the power generation price is high in the first half of the time period t(k+1) to tm and low in the second half of the time period t(k+1) to tm. Therefore, the generator output is not changed in the first half of the time period t(k+1) to tm, and power generation is stopped in the second half of the time period t(k+1) to tm. This makes it possible to reduce the total power generation amount yd(t(k+1))+yd(t(k+2)), ..., +yd(tm) of the modified power generation plan (4) below the total power generation amount ya(t(k+1))+ya(t(k+2)), ..., +ya(tm) of the initial power generation plan 21.

[0113] [C-3-3] When ΔEg(tk)>0 FIG. 17 is a diagram for explaining the generation of power plan formulation when ΔEg(tk)>0.

[0114] If ΔEg(tk)>0, the amount of stored thermal energy Eg(tk) is in excess of the required amount of energy Ea(tk). In this case, the power generation plan processing unit 7 outputs modified power generation plan (1), modified power generation plan (2), modified power generation plan (3), and modified power generation plan (5) as modified power generation plans 22. As shown in FIG. 17, these plans are also referred to as proposed plan (1), proposed plan (2), proposed plan (3), and proposed plan (5), respectively.

[0115] <Modified Power Generation Plan (1)> The power generation plan processing unit 7 modifies the modified power generation plan (1) by uniformly increasing all the generator outputs ya in the initial power generation plan 21, and formulates the modified power generation plan (1) from the initial power generation plan 21. The modified power generation plan (1) shown in FIG. 17 includes generator outputs ya"(t(k+1)), ya"(t(k+2)), ..., ya"(tm) at times t(k+1), t(k+2), ..., tm.

[0116] For example, if the initial power generation plan 21 includes ten generator outputs ya(0.5), ya(1), ya(1.5), ..., ya(5) at ten times t = 0.5, 1, 1.5, ..., 5, each generator output ya"(t) of the modified power generation plan (1) is given by the following equation (12).

number

[0117] , ya"(tm) is the sum of ya(0.5), ya"(1), ya"(1.5), ..., ya"(5) and ΔEg(tk) / 10, respectively. In the case of FIG. 17, ΔEg(tk) is positive, so ya"(0.5), ya"(1), ya"(1.5), ..., ya"(5) are greater than ya(0.5), ya(1), ya(1.5), ..., ya(5), respectively. This makes it possible to increase the total power generation amount ya"(t(k+1))+ya"(t(k+2)), ..., +ya"(tm) of the modified power generation plan (1) more than the total power generation amount ya(t(k+1))+ya(t(k+2)), ..., +ya(tm) of the initial power generation plan 21.

[0118] In addition, when ΔEg(tk)>0, the power generation plan processing unit 7 may output the initial power generation plan 21 as the modified power generation plan (1) without modifying it, as in the case of ΔEg(tk)=0. Also, in the case of ΔEg(tk)>0, the power generation plan processing unit 7 may output both the modified power generation plan (1) including ya(t(k+1)), ya(t(k+2)), ..., ya(tm) and the modified power generation plan (1) including ya"(t(k+1)), ya"(t(k+2)), ..., ya"(tm).

[0119] <Modified Power Generation Plan (2)> The power generation plan processing unit 7 formulates a modified power generation plan (2) from the initial power generation plan 21 by modifying the initial power generation plan 21 using the power generation price signal 24. The modified power generation plan (2) shown in Fig. 17 includes power generator outputs yb(t(k+1)), yb(t(k+2)), ..., yb(tm) at times t(k+1), t(k+2), ..., tm.

[0120] The modified power generation plan (2) when ΔEg(tk)>0 can be calculated in the same way as the modified power generation plan (2) when ΔEg(tk)=0. However, the modified power generation plan (2) when ΔEg(tk)>0 is calculated so as to satisfy the constraint that the required energy amount E(tk) (=Ed(tk)) calculated using equations (7) and (8) matches the stored thermal energy amount Eg(tk). This constraint is expressed by the following equation (13).

number

[0121] For example, if the power generation price is high in the first half of the time period t(k+1) to tm and low in the second half of the time period t(k+1) to tm (see FIG. 17), the generator output in the first half of the time period t(k+1) to tm is increased and the generator output in the second half of the time period t(k+1) to tm is not changed. This makes it possible to increase the total power generation amount yb(t(k+1))+yb(t(k+2)), ..., +yb(tm) of the modified power generation plan (2) more than the total power generation amount ya(t(k+1))+ya(t(k+2)), ..., +ya(tm) of the initial power generation plan 21.

[0122] <Modified Power Generation Plan (3)> The power generation plan processing unit 7 modifies the initial power generation plan 21 by solving an optimization problem using the amount of thermal energy stored Eg(tk), and formulates a modified power generation plan (3) from the initial power generation plan 21. The modified power generation plan (3) shown in Fig. 17 includes generator outputs yc(t(k+1)), yc(t(k+2)), ..., yc(tm) at times t(k+1), t(k+2), ..., tm.

[0123] The modified power generation plan (3) when ΔEg(tk) > 0 can be calculated in the same way as the modified power generation plan (3) when ΔEg(tk) = 0. This makes it possible to increase the total power generation amount yc(t(k+1)) + yc(t(k+2)), ..., + yc(tm) of the modified power generation plan (3) more than the total power generation amount ya(t(k+1)) + ya(t(k+2)), ..., + ya(tm) of the initial power generation plan 21.

[0124] <Modified Power Generation Plan (5)> The power generation plan processing unit 7 formulates a modified power generation plan (5) from the initial power generation plan 21 by modifying the initial power generation plan 21 so as to add power generation at times when the power generation price p is high. The modified power generation plan (5) shown in Fig. 17 includes power generator outputs ye(t(k-2)), ye(t(k-1)), ye(t(k)), ye(t(k+1)), ye(t(k+2)), ..., ye(tm) at times t(k-2), t(k-1), t(k), t(k+1), t(k+2), ..., tm.

[0125] The details of the modified power generation plan (5) are shown in FIG. 18. FIG. 18 is another diagram for explaining the formulation of a power generation plan when ΔEg(tk)>0. In FIG. 18, the power generation price is high in the first half of the time period t(k+1) to tm and low in the second half of the time period t(k+1) to tm, so the power generation start time is brought forward. Specifically, power generation from time period t(k-2) to t(k) is added to the power generation plan. This makes it possible to increase the total power generation amount ye(t(k-2))+ye(t(k-1)), ..., +ye(tm) of the modified power generation plan (5) more than the total power generation amount ya(t(k+1))+ya(t(k+2)), ..., +ya(tm) of the initial power generation plan 21.

[0126] The power generation plan processing unit 7 then determines and outputs an effective power generation plan 25 in response to an execution permission signal 23 that selects one of the one or more modified power generation plans 22. The power generation plan processing unit 7 outputs the amount of power generation (power generator output) at each time included in the effective power generation plan 25 to the power generation control unit 8 as a power generation command signal 17 as time progresses.

[0127] According to this embodiment, the amount of thermal energy stored Eg(tk) can be calculated with high accuracy by the above-described process. The one or more temperature measuring devices 6 of this embodiment are appropriately arranged to perform such a process. Furthermore, according to this embodiment, by modifying the initial power generation plan 21 using Eg(tk), it is possible to accurately calculate an appropriate modified power generation plan 22.

[0128] [D] First Modification FIG. 19 is a graph for explaining the interpolation process (linear interpolation) of the first modified example of the first embodiment.

[0129] In the above embodiment, since it is essential to obtain the internal temperature of the heat storage section 2 with high accuracy, for example, about 20 to 100 temperature measuring devices 6 are installed. However, using a large number of temperature measuring devices 6 has the following problems. First, it takes time and effort to install the temperature measuring devices 6. Second, it takes time and effort to calibrate the temperature measuring devices 6. Third, it takes time and effort to maintain the temperature measuring devices 6 when they are used for a long period of time. Fourth, the cost of preparing the temperature measuring devices 6 increases depending on the number of temperature measuring devices 6.

[0130] Therefore, in this modified example, an interpolation process is performed on the internal temperature to reduce the number of installed temperature measuring devices 6. The number of installed temperature measuring devices 6 in this modified example is, for example, about 15.

[0131] In Figure 19, the horizontal axis represents the position x of the heat storage unit 2, with low-temperature heat transfer fluid 13a flowing in from the left and flowing to the right, and high-temperature heat transfer fluid 13b flowing out from the right. In other words, an example is shown in which the length of the heat storage unit 2 is 10 [m]. The vertical axis represents the internal temperature of the heat storage unit 2. In other words, Figure 19 shows that, for example, at a location 4 [m] from the inlet of the heat transfer fluid, the internal temperature of the heat storage unit 2 is 180 [°C].

[0132] In FIG. 19, the solid line represents the true value of the internal temperature of the thermal storage unit 2. The circles (◯) represent the measured temperatures indicated by the temperature measurement value signals 16 output from the temperature measuring devices 6. Here, 11 temperature measuring devices 6 are installed at 1 m intervals from left to right. The dashed lines represent values ​​obtained by linearly interpolating the measured temperatures of the temperature measurement signals 16. It can be seen from FIG. 19 that by using approximately 11 temperature measurement signals 16, it is possible to calculate a value that nearly matches the true value by linear interpolation. This linear interpolation calculation can be performed in the power generation planning processing unit 7.

[0133] According to this modification, it is possible to accurately determine the internal temperature of the heat storage unit 2 by using about 15 temperature measuring devices 6 and using values ​​obtained by linearly interpolating the measured temperatures of the temperature measurement signals 16. As a result, it is possible to accurately calculate the amount of thermal energy stored Eg(tk).

[0134] [E] Second Modification FIG. 20 is a graph for explaining the interpolation process (spline interpolation) of the second modified example of the first embodiment.

[0135] In the first modified example, for example, about 15 temperature measuring devices 6 are used to accurately grasp the internal temperature of the heat storage section 2. In this modified example, the number of installed temperature measuring devices 6 is further reduced. For example, the number of installed temperature measuring devices 6 in this modified example is about 10.

[0136] The vertical and horizontal axes in Figure 20 are the same as those in Figure 19. The solid line represents the true value of the internal temperature of the thermal storage unit 2. The circles (◯) represent the measured temperature indicated by the temperature measurement value signal 16 output from the temperature measuring device 6. Here, six temperature measuring devices 6 are installed at 2 [m] intervals from left to right. The dashed line represents the value obtained by linearly interpolating the measured temperature of the temperature measurement signal 16. The dots (small black dots) represent the value obtained by spline interpolation of the measured temperature of the temperature measurement signal 16. It can be seen that the linearly interpolated value differs greatly from the true value in some places, but the spline interpolated value is almost equal to the true value. This spline interpolation calculation can be performed in the power generation planning processing unit 7.

[0137] According to this modification, by using about 10 temperature measuring devices 6 and using values ​​obtained by spline interpolation of the measured temperatures of the temperature measurement signals 16, it is possible to obtain the internal temperature of the heat storage section 2 with higher accuracy. As a result, it is possible to calculate the amount of thermal energy Eg(tk) with higher accuracy. On the other hand, the linear interpolation of the first modification can generally be performed more easily than the spline interpolation of the second modification.

[0138] As described above, the thermal storage power generation system of this embodiment measures the internal temperature of the thermal storage unit 2 using one or more temperature measuring devices 6, and controls the power generation performed by the power generation unit 3 based on the internal temperatures measured by these temperature measuring devices 6. For example, the thermal storage power generation system of this embodiment determines a function Ts(xa, tk) that indicates the internal temperature distribution using the internal temperatures measured by these temperature measuring devices 6, calculates the amount of thermal stored energy Eg(tk) using the function Ts(xa, tk), formulates a power generation plan using the amount of thermal stored energy Eg(tk), and controls power generation based on this power generation plan. Therefore, according to this embodiment, it is possible to operate the thermal storage unit 2 and the power generation unit 3 of the thermal storage power generation system in a suitable manner.

[0139] Although several embodiments have been described above, these embodiments are presented only as examples and are not intended to limit the scope of the invention. The novel system described in this specification can be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications can be made to the forms of the system described in this specification without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover such forms and modifications that fall within the scope and spirit of the invention. [Explanation of symbols]

[0140] 1: heating section, 2: heat storage section, 3: power generation section, 4a: first air blowing section, 4b: second air blowing section, 5: power generation output measuring instrument, 6, 6a, 6b: temperature measuring instrument, 7: power generation planning processing unit, 8: power generation control unit, 9: air flow control unit, 11: Energy input, 12a, 12b, 12c, 12d: Heat transfer fluid, 13a, 13b, 13c, 13d: heat transfer fluid, 14: power generation output, 15: power generation output measurement signal, 16, 16a, 16b: temperature measurement signal, 17: power generation command signal, 18: power generation control signal, 19a: first air blowing control signal, 19b: second air blowing control signal, 21: Initial power generation plan, 22: Modified power generation plan, 23: Execution permission signal, 24: Power generation price signal, 25: Execution power generation plan

Claims

1. a heating unit that heats the first heat transfer fluid; a heat storage unit including a heat storage material heated by the first heat transfer fluid, the heat storage unit heating a second heat transfer fluid by heat stored in the heat storage material; a power generation unit that generates power using the second heat transfer fluid; One or more temperature measuring devices that measure the internal temperature of the heat storage unit; a power generation plan processing unit that formulates a power generation plan for the power generation unit based on the internal temperature measured by the temperature measuring device; a power generation control unit that controls the power generation performed by the power generation unit based on the power generation plan; A thermal storage power generation system comprising:

2. The thermal storage power generation system according to claim 1 , wherein the power generation plan processing unit outputs, as the power generation plan, a modified power generation plan formulated by modifying an initial power generation plan.

3. The thermal storage power generation system according to claim 2 , wherein the power generation plan processing unit outputs, as the power generation plan, an actual power generation plan selected from the modified power generation plans.

4. The thermal storage power generation system according to any one of claims 1 to 3, wherein the power generation plan processing unit determines a distribution of the internal temperature as a function of location and time based on the internal temperature measured by the temperature measuring device, and formulates the power generation plan based on the distribution of the internal temperature.

5. The thermal storage power generation system according to claim 4 , wherein the power generation plan processing unit determines the distribution of the internal temperature using linear interpolation.

6. The thermal storage power generation system according to claim 4 , wherein the power generation plan processing unit determines the distribution of the internal temperature using spline interpolation.

7. The thermal storage power generation system according to any one of claims 4 to 6, wherein the power generation plan processing unit calculates the amount of thermal energy stored in the thermal storage unit that is available for power generation between a predetermined time in the heat dissipation mode and a power generation end time based on the distribution of the internal temperature, and formulates the power generation plan based on the amount of stored thermal energy.

8. The thermal storage power generation system according to claim 7 , wherein the power generation plan processing unit outputs an initial power generation plan as the power generation plan when the amount of stored thermal energy is equal to the amount of required energy.

9. The thermal storage power generation system of claim 7, wherein when the amount of stored thermal energy is less than the required energy amount, the power generation plan processing unit outputs, as the power generation plan, a modified power generation plan formulated by modifying the initial power generation plan so as to reduce the total power generation amount of the power generation unit.

10. The thermal storage power generation system of claim 7, wherein when the amount of stored thermal energy is greater than the required energy amount, the power generation plan processing unit outputs, as the power generation plan, a modified power generation plan formulated by modifying the initial power generation plan so as to increase the total power generation amount of the power generation unit.

11. The thermal storage power generation system according to claim 7 , wherein the power generation plan processing unit formulates the power generation plan based on the amount of thermal energy stored and a power generation price.

12. The thermal storage power generation system according to claim 7 , wherein the power generation plan processing unit formulates the power generation plan by solving an optimization problem using the amount of thermal energy stored.

13. a first blower section that circulates the first heat transfer fluid between the heating section and the heat storage section; a second blower section that circulates the second heat transfer fluid between the heat storage section and the power generation section; an air blowing control unit that controls the operation of the first and second air blowing units; The thermal storage power generation system according to claim 1 , further comprising:

14. a heating unit that heats the first heat transfer fluid; a heat storage unit including a heat storage material heated by the first heat transfer fluid, the heat storage unit heating a second heat transfer fluid by heat stored in the heat storage material; a power generation unit that generates power using the second heat transfer fluid; A power generation control system for controlling a thermal storage power generation system comprising: One or more temperature measuring devices that measure the internal temperature of the heat storage unit; a power generation plan processing unit that formulates a power generation plan for the power generation unit based on the internal temperature measured by the temperature measuring device; a power generation control unit that controls the power generation performed by the power generation unit based on the power generation plan; A power generation control system comprising:

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