Power procurement equipment

Abstract

To provide a power procurement device capable of suppressing the generation of an imbalance.SOLUTION: A power procurement device performs a procurement of a power by supplying a power to a power system from a power supplier. The power supplier comprises: a fuel battery device; and a power consumption device. A residual power obtained by subtracting a consumption power of the power consumption device from an output power of the fuel battery device can be supplied to a power system as an inverse load power. In the case where the output power of the fuel battery device can be changed at a predetermined maximum change rate, it is determined that an inverse load power amount supplied to the power system by the power supplier in an object time band can be set to a value that a difference of the inverse load power amount and a predetermined target inverse load power amount becomes within a predetermined range with an assumption that the output power of the fuel battery device at a termination point of a predetermined object time band is set to a predetermined termination output power.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a power procurement device that procures power by causing a power supplier to supply power to a power system.

Background Art

[0002] In a power system, not only large-scale power plants that have existed conventionally but also power source devices such as power generation devices and charge / discharge devices installed in facilities such as houses and offices are connected. Further, power consumption devices installed in facilities are also connected to the power system. In recent years, under the concept of a virtual power plant (VPP), power generation companies have attempted to control the operation of customer-side energy resources such as the above-described power source devices and power consumption devices installed in customers' facilities.

[0003] For example, when a power generation company procures power from a power supplier that owns a power source device, the surplus power, which is the value obtained by subtracting the power consumption of the power consumption device from the output power of the power source device of the power supplier, becomes the procurement power from that power supplier. For example, as shown in FIG. 8, considering four 30-minute frames from time 12:00 to time 14:00, the power generation company can remotely control the power source device of the power supplier to operate at a predetermined output power (0.7 kW) to generate surplus power as shown in each 30-minute frame and cause reverse power flow to the power system.

[0004] Furthermore, since power generators can also procure electricity from other sources, such as the electricity trading market, it is preferable to procure electricity from other sources during specific 30-minute time slots when the electricity procurement unit price from other sources is lower than the electricity procurement unit price when purchasing surplus electricity from the electricity supplier. Figure 9 shows an example of a power generator procuring electricity from the electricity trading market during a 30-minute time slot between 12:30 and 13:00. In this case, the power generator remotely controls the electricity supplier's power supply to operate at a predetermined output power (0.7kW) until 12:30, and remotely controls the electricity supplier's power supply to operate at output power x during the target time slot between 12:30 and 13:00. As a result, the reverse power flow amount shown in the figure is supplied to the power grid during the target time slot between 12:30 and 13:00.

[0005] In this way, power generators can procure electricity more economically by, for example, changing their procurement method to procure electricity from a specific power supplier if the price of electricity from that supplier becomes cheaper.

[0006] Furthermore, for electricity procured by power generation operators, it is necessary to match the planned and actual values ​​of electricity procured every 30 minutes within the framework of a power generation balancing group, which includes power sources such as power plants and electricity trading markets, as well as power suppliers equipped with the aforementioned power supply equipment. Any difference in the figures will be settled as an imbalance for the power generation operator.

[0007] Patent Document 1 (Japanese Patent Publication No. 2019-215693) describes a power trading support device aimed at reducing imbalance penalties. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2019-215693 [Overview of the project] [Problems that the invention aims to solve]

[0009] Furthermore, if the power supplier's power source is a fuel cell system, there is an upper limit to the rate at which the output power changes. Therefore, as shown in Figure 10, even if the fuel cell system's output power starts to increase at 13:00, it will take some time for the fuel cell system's output power to actually reach 0.7kW, resulting in a power deficit during that time. In other words, although the fuel cell system's output power should ideally be 0.7kW at 13:00, that is, at the end of the target time period between 12:30 and 13:00, it is not. As a result, there is a possibility that an imbalance will occur in the next time period between 13:00 and 13:30, where the actual power generation value does not match the pre-planned power generation value.

[0010] This invention has been made in view of the above-mentioned problems, and its objective is to provide a power procurement device that can suppress the occurrence of imbalances. [Means for solving the problem]

[0011] A characteristic configuration of the power procurement device according to the present invention for achieving the above objective is a power procurement device that procures electricity by having electricity supplied from a power supplier to the power grid, The aforementioned power supplier is equipped with a fuel cell device and a power consumption device, and can supply the surplus power obtained by subtracting the power consumption of the power consumption device from the output power of the fuel cell device as reverse power flow power to the power grid. The objective is to determine whether, given that the output power of the fuel cell device can be changed at a predetermined maximum rate of change, the amount of reverse power supplied by the power supplier to the power grid during a predetermined target time period can be set to a value such that the difference between the reverse power supply amount and a predetermined target reverse power supply amount falls within a predetermined range from the target reverse power supply amount, assuming that the output power of the fuel cell device at the end of a predetermined target time period is set to a predetermined end-of-time output power.

[0012] According to the above characteristic configuration, by setting the output power of the fuel cell device at the end of the target time period to a predetermined end-of-period output power (for example, the power that the fuel cell device should output at the start of the next time period after the target time period), it is possible to prevent imbalance from occurring in the time period following the target time period.

[0013] Furthermore, setting the output power of the fuel cell device at the end of the target time period to a predetermined end-of-period output power can lead to the generation of unnecessary reverse power flow. As a result, the amount of reverse power flow during the target time period may increase, potentially causing an imbalance. However, this feature configuration determines whether the amount of reverse power flow supplied by the power supplier to the power grid during the target time period can be set so that the difference between that reverse power flow amount and a predetermined target reverse power flow amount falls within a predetermined range from that target reverse power flow amount. In other words, it is possible to verify in advance whether an imbalance may occur during a particular target time period if the system is designed to prevent an imbalance from occurring in the time period following that specific target time period. Therefore, it is possible to provide a power procurement device that can suppress the occurrence of imbalances.

[0014] Another characteristic configuration of the power procurement device according to the present invention is that the target reverse power flow amount is set to a value obtained by subtracting the amount of electricity that can be procured from the power trading market within a range that does not exceed the maximum reverse power flow amount, which is the maximum amount of reverse power flow that the power supplier can supply to the power grid during the target time period.

[0015] If, during the relevant time period, the electricity procurement price when procuring electricity from the electricity trading market is lower than the electricity procurement price when purchasing reverse power flow electricity from the electricity supplier, the electricity supplier may plan to procure a portion of the reverse power flow electricity that it had planned to supply to the power grid during the relevant time period from the electricity trading market. In this configuration, the target reverse power flow amount is set to a value obtained by subtracting the amount of electricity that can be procured from the electricity trading market within a range that does not exceed the maximum reverse power flow amount, which is the maximum amount of reverse power flow amount that the power supplier can supply to the power grid during the target time period. Then, it is possible to determine whether the amount of reverse power flow amount that the power supplier supplies to the power grid during the target time period can be set to a value where the difference between that reverse power flow amount and the target reverse power flow amount falls within a predetermined range from the target reverse power flow amount.

[0016] A further characteristic configuration of the power procurement device according to the present invention is that, from the start of the target time period to a transient point in the middle of the target time period, the fuel cell device is operated with the output power set to a constant assumed value, and from the transient point to the end point, the fuel cell device is operated while changing the output power from the assumed value to the output power at the maximum rate of change. The key point is that the reverse power flow amount is determined by accumulating the predicted surplus power obtained by subtracting the average predicted power consumption of the power consumption device during the target time period from the output power of the fuel cell device at each point in time during the target time period.

[0017] According to the above characteristic configuration, the amount of reverse power flow can be derived when the fuel cell device is operated with a constant assumed output power from the start of the target time period to a transient point in the middle of that time period, and when the fuel cell device is operated while changing the output power from the assumed value to the output power at the end of the target time period at the maximum rate of change. [Brief explanation of the drawing]

[0018] [Figure 1] This diagram shows the configuration of a system in which power procurement equipment is installed. [Figure 2] This figure shows an example of the trends in output power, power consumption, and surplus power. [Figure 3] This figure shows an example of the trends in output power, power consumption, and surplus power. [Figure 4]Flowchart for explaining the process of determining the target reverse power flow [Figure 5] It is a diagram showing examples of the transitions of output power, power consumption, and surplus power. [Figure 6] It is a diagram showing examples of the transitions of output power, power consumption, and surplus power. [Figure 7] It is a diagram showing examples of the transitions of output power, power consumption, and surplus power. [Figure 8] It is a diagram showing examples of the transitions of output power, power consumption, and surplus power. [Figure 9] It is a diagram showing examples of the transitions of output power, power consumption, and surplus power. [Figure 10] It is a diagram showing examples of the transitions of output power, power consumption, and surplus power.

Embodiments for Carrying Out the Invention

[0019] The power supply device 4 according to the embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of a system in which the power supply device 4 is provided. As shown in the figure, the power supplier 10 and the power source equipment 2 connected to the power grid 1 are set as the balancing group G. The power supply device 4 is configured to be able to communicate information with the power supplier 10, the power source equipment 2, the power trading market 3, etc. via an information communication line. In FIG. 1, three power suppliers 10 are depicted, but the number of power suppliers 10 can be changed as appropriate. Each power supplier 10 includes a fuel cell device 11 and a power consumption device 12. The power source equipment 2 is equipment such as a thermal power generation facility, a wind power generation facility, a solar power generation facility, etc. The power supplier 10 can supply the surplus power obtained by subtracting the power consumption of the power consumption device 12 from the output power of the fuel cell device 11 to the power grid 1 as reverse power flow.

[0020] The power supplied by the power supplier 10 and the power source equipment 2 is determined by the power supply device 4. That is, the power supply device 4 performs power procurement by causing the balancing group G including the power supplier 10 and the power source equipment 2 to supply power to the power grid 1.

[0021] For example, as shown in Figure 8, the power generation operator's power procurement device 4 determines the surplus power (i.e., reverse power flow) to be supplied from the power supplier 10 to the power grid 1 and transmits this information to the power supplier 10. Furthermore, since the power generation operator can also procure power from other sources, such as the power trading market 3, it is preferable to procure power from other sources during specific 30-minute time slots (i.e., 30-minute time periods) when the power procurement unit price for procuring power from other sources is lower than the power procurement unit price for purchasing surplus power from the power supplier 10.

[0022] Figure 2 shows an example where a power generator procures electricity from an alternative power source, the electricity trading market 3, during the target time period between 12:30 and 13:00. The figures shown in Figure 2 represent the average values ​​of multiple power suppliers 10 included in balancing group G. Specifically, this is an example where the average rated output power of multiple fuel cell devices 11 owned by the multiple power suppliers 10 included in balancing group G is 0.7 kW. Furthermore, the schematic representation of the electricity amount per bidding unit corresponds to the actual electricity amount per bidding unit divided by the number of power suppliers 10 included in balancing group G. Thus, in this embodiment, instead of using the overall values ​​for balancing group G, which includes multiple power suppliers 10, average values ​​are used in some explanations.

[0023] The power generator remotely instructs the power supplier 10's fuel cell device 11 to operate at, for example, a rated output power of 0.7 kW until 12:30 and from 13:00 to 13:30, and remotely instructs the power supplier 10's fuel cell device 11 to operate at a predetermined output power x1 from 12:30 to 13:00. In addition, the power generator procures electricity from another power source, the electricity trading market 3, between 12:30 and 13:00.

[0024] In the electricity trading market 3, since the bidding unit for procuring electricity is fixed, of the amount of electricity that electricity supplier 10 was scheduled to supply between 12:30 and 13:00, an amount that is an integer multiple of that bidding unit will be procured from the electricity trading market 3, and the remaining amount of electricity must be covered by the reverse power flow from electricity supplier 10.

[0025] Furthermore, as shown in Figure 3, the power supplier 10 needs to change the output power of the fuel cell device 11 at a predetermined maximum rate of change, so that the output power of the fuel cell device 11 at the end of a predetermined target time period is the predetermined end-of-period output power. Otherwise, as shown in Figure 10, the amount of reverse power flow from the power supplier 10 to the power system 1 between 13:00 and 13:30 will decrease by the amount of the power deficit shown, resulting in a difference between the planned power generation value and the actual power generation value.

[0026] However, setting the output power of the fuel cell device 11 at the end of the target time period to a predetermined end-of-period output power would lead to the generation of unnecessary reverse power flow. In other words, the amount of reverse power flow during the target time period may increase, potentially causing an imbalance during that period.

[0027] Therefore, the power procurement device 4 determines whether the amount of reverse power flow supplied by the power supplier 10 to the power system 1 during the target time period can be set so that the difference between that reverse power flow amount and a predetermined target reverse power flow amount falls within a predetermined range from that target reverse power flow amount. In other words, it verifies in advance whether an imbalance may occur during a specific target time period if an imbalance is prevented from occurring in the time period following that specific target time period.

[0028] Specifically, the power procurement device 4, assuming that the output power of the fuel cell device 11 can be changed at a predetermined maximum rate of change, determines whether the amount of reverse power supplied by the power supplier 10 to the power system 1 during the target time period can be set to a value such that the difference between the amount of reverse power supplied and a predetermined target amount of reverse power is within a predetermined range from the target amount of reverse power.

[0029] Next, we will explain the procedure for determining the target reverse power flow amount for the target time period. Figure 4 is a flowchart illustrating the process for determining the target reverse power flow amount. The power procurement device 4 executes this flowchart before the target time period if the unit price of the reverse power flow amount procured from power supplier 10 is higher than the unit price of the amount procured from other power suppliers during the target time period.

[0030] In step #10, the power procurement device 4 provisionally determines the target reverse power flow amount. In this case, as shown in Figure 2, the target reverse power flow amount is set to a value obtained by subtracting the amount of electricity that can be procured from the power trading market 3 within a range that does not exceed the maximum reverse power flow amount, which is the maximum amount of reverse power flow that the power supplier 10 can supply to the power system 1 during the target time period. Here, since "maximum surplus power = rated output power - predicted power consumption", the maximum surplus power amount is realized when the maximum surplus power is supplied to the power system 1 during the target time period.

[0031] To explain in more detail, in the electricity trading market 3, the unit of electricity that can be bid on is fixed, so the amount of electricity that can be procured from the electricity trading market 3 will be an integer multiple of that unit of electricity. Therefore, the power procurement device 4 can determine the maximum amount of electricity that can be procured from the electricity trading market 3 (however, an integer multiple of the unit of electricity) as long as it does not exceed the maximum reverse power flow amount. Then, the power procurement device 4 tentatively determines the target reverse power flow amount as the value obtained by subtracting the maximum procured amount from the maximum reverse power flow amount.

[0032] Next, in step #11, when the power supply device 4 can change the output power of the fuel cell device 11 at a predetermined maximum change rate, on the premise that the output power of the fuel cell device 11 at the end of a predetermined target time period is set to a predetermined end output power, it is determined whether the reverse power flow amount supplied by the power supplier 10 to the power grid 1 in the target time period can be set to a value such that the difference between the reverse power flow amount and a predetermined target reverse power flow amount is within a predetermined range from the target reverse power flow amount.

[0033] When the number of power suppliers 10 included in the balancing group G is N, the number of fuel cell devices 11 included in the balancing group G is N. As shown in FIG. 2, in the target time period from 12:30 to 13:00, the average output power x1 [kW / unit], average power consumption a1 [kW / unit], and target reverse power flow xt (= x1 - a1) [kW / unit] of N fuel cell devices 11 are set, and it is assumed that the output power of these N fuel cell devices 11 is controlled. At this time, the target reverse power flow amount by the N fuel cell devices 11 (a plurality of power suppliers 10) is 30 × xt × N [kWm]. In practice, in order to set the output power of the fuel cell device 11 at 13:00 to the end output power, as shown in FIG. 3, it is necessary to change the output power of the fuel cell device 11 during the target time period.

[0034] That is, as shown in FIG. 3, from the start time of the target time period to the transient time t1 in the middle of the target time period, the fuel cell device 11 is operated with the output power set to a certain assumed value x2, and during the output increase period b1 from the transient time t1 to the end time (13:00), the fuel cell device 11 is assumed to be operated while changing the output power from the assumed value x2 to the end output power (0.7 kW in this embodiment) at the maximum change rate. The assumed value x2 and the output increase period b1 (0 < b1 < 30) in this case can be calculated as follows.

[0035] Since the target reverse power flow amount 30 × xt × N [kWm] in FIG. 2 is equal to the reverse power flow amount in FIG. 3, the following equation (1) holds.

[0036]

Equation

[0037] The maximum change rate R [kW / m] of the output power of the fuel cell device 11 is expressed by the following formula (2) because of the slope when increasing the output.

Number

[0038] Therefore, from formula (1), formula (2), and x2 > 0, the following formulas (3) and (4) hold.

Number

[0039] If x2 ≥ a1, no imbalance will occur. That is, the power supply device 4 determines that it can make the reverse power flow amount supplied by the power supplier 10 to the power grid 1 within the target time period such that the difference between the reverse power flow amount and a predetermined target reverse power flow amount is within a predetermined range from the target reverse power flow amount.

[0040] In addition, when x2 < a1, it can be said that the state is as shown in FIGS. 5 and 6. However, even if x2 < a1, it is sufficient that the imbalance generated is within a predetermined range from the target reverse power flow amount. Here, the reverse power flow amount when x2 = a1 in FIGS. 2 and 5 is expressed by the following formula (5).

Number

[0041] When x2 = a1 in the above formula (2), since R = (0.7 - a1) / b1, the reverse power flow amount becomes the following formula (6).

Number

[0042] Therefore, the difference between the target reverse power flow amount (30 × x1 × N [kWm]) shown in FIG. 1 and the reverse power flow amount (Equation (6)) when x2 = a1 becomes the imbalance shown in the following Equation (7).

Equation

[0043] And, when the imbalance tolerance rate with respect to the target reverse power flow amount (30 × x1 × N [kWm]) is α [%], Equation (7) only needs to be below 30 × xt × N × α [kWm] corresponding to a predetermined range from the target reverse power flow amount. That is, the following Equation (8) only needs to hold.

[0044]

Equation

[0045] Thus, when x2 ≥ a1, or even when x2 < a1 as long as Equation (8) holds, in step #11, the power procurement device 4 determines that the reverse power flow amount supplied by the power supplier 10 to the power grid 1 in the target time period is such that the difference between the reverse power flow amount and a predetermined target reverse power flow amount is within a predetermined range from the target reverse power flow amount. And in step #12, the power procurement device 4 finally determines that target reverse power flow amount.

[0046] Then, the power procurement device 4 commands the power supplier 10 with that target reverse power flow amount. For example, when a plurality of power suppliers 10 are included in the balancing group G, the target reverse power flow amount is distributed and commanded to each power supplier 10. Also, the power procurement device 4 sets the power procurement amount from the power trading market 3 in the target time period to a value obtained by subtracting the target reverse power flow amount from the maximum reverse power flow amount, which is the maximum value of the reverse power flow amount that the power supplier 10 can supply to the power grid 1 in the target time period, and procures that power amount in the power trading market 3.

[0047] In response, if the power procurement device 4 determines in step #11 that the amount of reverse power flow supplied by the power supplier 10 to the power system 1 during the target time period is such that the difference between the reverse power flow amount and a predetermined target reverse power flow amount does not fall within a predetermined range from the target reverse power flow amount, it proceeds to step #13.

[0048] In step #13, the power procurement device 4 increases the target reverse power flow amount. Specifically, as shown in Figure 7, the power procurement device 4 increases the target reverse power flow amount by the amount of the bid unit to the power trading market 3, and sets that value as the provisional target reverse power flow amount. Then, the power procurement device 4 performs the determination in step #11 again.

[0049] As described above, by setting the output power of the fuel cell device 11 at the end of the target time period to a predetermined end-of-period output power (for example, the power that the fuel cell device 11 should output at the start of the next time period after the target time period), it is possible to prevent imbalance from occurring in the next time period after the target time period.

[0050] Furthermore, the power procurement device 4 determines whether the amount of reverse power flow supplied by the power supplier 10 to the power system 1 during the target time period can be set so that the difference between that reverse power flow amount and a predetermined target reverse power flow amount falls within a predetermined range from that target reverse power flow amount. In other words, it can verify in advance whether an imbalance may occur during a specific target time period if it is determined that no imbalance will occur in the time period following that specific target time period. Then, it can determine a target reverse power flow amount that will not cause an imbalance.

[0051] <Another Embodiment> <1> In the above embodiment, the configuration of a system equipped with a power procurement device 4 was illustrated, but the configuration can be changed as appropriate. For example, in the above embodiment, an example was described in which the power procurement device 4 commands the power supplier 10 with a command value corresponding to the target reverse power flow amount. However, a system other than the power procurement device 4 may be configured to transmit the command value corresponding to the target reverse power flow amount to the power supplier 10.

[0052] <2> In the above embodiment, an example was described in which, if the power procurement device 4 determines "No" in step #11, the target reverse power flow amount is increased in step #13. However, the power procurement device 4 may perform other processes. For example, as shown in Figure 10, the fuel cell device 11 may be operated with a constant value x for output power during the target time period from 12:30 to 13:00, and then the output power of the fuel cell device 11 may be changed from the constant value x to the target output power (0.7kW) during the next time period (from 13:00 to 13:30).

[0053] In other words, if the power procurement device 4 purchases surplus power from the power supplier 10 during a specific time period, and the power procurement price is higher than the power procurement price when procuring power from another power source, such as the power trading market 3, then the power procurement device 4 sets the target reverse power flow amount for the power supplier 10 during that time period to a value obtained by subtracting the amount of power that can be procured from the power trading market 3 (i.e., the maximum amount of power procured) within a range that does not exceed the maximum reverse power flow amount, which is the maximum amount of reverse power flow amount that the power supplier 10 can supply to the power system 1 during that time period, and then instructs the power supplier 10 to set this target reverse power flow amount. The power procurement device 4 also sets the amount of power procured from the power trading market 3 during that time period to the above maximum amount of power procured, and procures that amount of power from the power trading market 3.

[0054] <3> In the above embodiment, the present invention was described by giving numerical examples of the output power of the fuel cell device 11 at the end of operation, but these numerical values ​​are given for illustrative purposes only and can be changed as appropriate.

[0055] <4> The configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. Furthermore, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto and can be modified as appropriate without departing from the purpose of the present invention. [Industrial applicability]

[0056] This invention can be used in power procurement devices that can suppress the occurrence of imbalances. [Explanation of symbols]

[0057] 1 Power system 2 Power equipment 3. Electricity Trading Market 4. Power procurement equipment 10 Electricity supplier 11 Fuel cell device 12 Power consumption equipment

Claims

1. A power procurement device that procures electricity by having electricity supplied to the power grid from electricity suppliers, The aforementioned power supplier is equipped with a fuel cell device and a power consumption device, and can supply the surplus power obtained by subtracting the power consumption of the power consumption device from the output power of the fuel cell device as reverse power flow power to the power grid. A power procurement device that, when the output power of the fuel cell device can be changed at a predetermined maximum rate of change, determines whether the amount of reverse power supplied by the power supplier to the power grid during the target time period can be set to a value such that the difference between the amount of reverse power supplied and a predetermined target amount of reverse power supplied is within a predetermined range from the target amount of reverse power supplied, based on the premise that the output power of the fuel cell device at the end of a predetermined target time period will be a predetermined end-of-period output power.

2. The power procurement device according to claim 1, wherein the target reverse power flow amount is set to a value obtained by subtracting the amount of electricity that can be procured from the electricity trading market within a range not exceeding the maximum reverse power flow amount, which is the maximum amount of reverse power flow that the power supplier can supply to the power grid during the target time period.

3. Assuming that the fuel cell device is operated with the output power set to a constant assumed value from the start of the target time period to a transient point in the middle of the target time period, and that the fuel cell device is operated while changing the output power at the maximum rate of change from the assumed value to the output power at the end of the period, The power procurement device according to claim 1 or 2, wherein the predicted surplus power obtained by subtracting the average predicted power consumption of the power consumption device during the target time period from the output power of the fuel cell device at each point in time during the target time period is accumulated during the target time period to determine the reverse power flow amount.

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