Power interchanging system

Abstract

To provide a power interchanging system for transmitting power from a power generation system formed of solar batteries, in which demand imbalance is restrained when power is transmitted to a plurality of demander locations.SOLUTION: A power interchanging system according to the present invention collects power generation amounts of a plurality of power generator locations and power demands in a plurality of demander locations, thereby calculates transmission power from a power generation system to the demander locations, and determines a power transmission destination of the transmission power so as to transmit power most preferentially to a demander location having the smallest overtime fluctuation of a power demand.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a technique for transmitting electric power generated by a power generation system including solar cells between bases via a power transmission network. [Background technology]

[0002] Self-dispatch is when a business operator with power generation facilities uses the power grid owned by the power company to transmit the electricity generated by the power generation facilities between bases. When implementing self-dispatch, it is necessary to submit a transmission plan to the operating organization (e.g. Organization for Cross-regional Coordination of Transmission Operators: OCCTO) before starting the dispatch (e.g. the day before). Furthermore, while implementing self-dispatch, it is necessary to transmit the electricity as planned at specified time intervals (e.g. 30 minutes). If the actual transmitted power deviates from the planned power (imbalance), a penalty is generally imposed.

[0003] There are two types of imbalances: generation imbalances and demand imbalances. Generation imbalances occur when electricity is not generated as planned. If the actual power generation is greater than the power generation plan, a surplus imbalance has occurred, and if it is less, a shortage imbalance has occurred. Demand imbalances occur when consumption is not consumed as planned. If the actual demand is greater than the demand plan, a shortage imbalance has occurred, and if it is less, a surplus imbalance has occurred.

[0004] The following Patent Document 1 aims to provide a plan creation device capable of creating a transmission plan that enables transmission of electricity from a first base equipped with a storage battery and a generator to a second base while managing the remaining charge of the storage battery, and describes a technology in which "a plan creation device creates a transmission plan for electricity from a first base equipped with a storage battery and a generator to a second base, the plan creation device comprising an acquisition unit that acquires a power demand at the first base, and a creation unit that creates the transmission plan including an operation plan for the storage battery that satisfies a constraint condition related to the remaining charge of the storage battery based on the acquired power demand" (see abstract).

[0005] The following Patent Document 2 addresses the issue that "it has not yet been possible to build a power supply system configuration that contributes to planned power generation that minimizes risk while taking into account the occurrence of prediction errors inherent in solar radiation prediction technology and battery management technology, or to optimize these power generation plans," and describes a technology in which "a power transmission plan is formulated based on a predicted value of surplus power, which is based on the difference between the predicted value of power generation by renewable energy and the predicted value of power demand, and which is equipped with a power supply system that is equipped with a control unit that controls the production and storage of hydrogen, the charge amount of the storage battery, and the power generation amount of the fuel cell, based on the comparison result between the predicted value of the surplus power and the actual value, and the comparison result between the charging rate of the storage battery and a first set value" (see abstract).

[0006] Japanese Patent Application No. 2022-144964 describes a technology that assumes that a power generation system that generates power to be transmitted by self-consignment is composed of solar cells and storage batteries. In this document, the power to be charged and discharged by the storage battery is calculated based on the difference between the planned power that was scheduled to be transmitted by the power transmission network and the actual power that was actually transmitted, and the power that needs to be generated by the solar cell is also calculated. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2021-141778 A [Patent Document 2] JP 2020-054085 A Summary of the Invention [Problem to be solved by the invention]

[0008] Consider a case where a power generation system that generates power to be transmitted by self-dispatch is composed of, for example, a solar cell and a storage battery. In order to transmit power in compliance with a pre-planned plan while performing self-dispatch, when the solar cell generates power in excess of the planned transmission power, it is necessary to suppress the amount of power generation to be less than the maximum power point and to use the surplus power generation to charge the storage battery. In other words, when the amount of power generation from the power generation system exceeds the planned transmission power as planned in advance, the solar cell is instructed to suppress the amount of power generation to be less than the maximum power point and the storage battery is instructed to perform a charging operation. Conversely, when the amount of power generation from the solar cell is less than the planned transmission power, the storage battery is discharged.

[0009] Consider the case where power is transmitted from multiple power generation bases to a demand base. In this case, typically, one of the power generation bases becomes a parent base, the other power generation bases become child bases, and the parent base controls all of the power generation bases. In this case, the parent base predicts in advance the amount of power generated from the solar cells at each power generation base, and determines the amount of charging and discharging from the storage battery according to the predicted amount of power generation. Therefore, in order to comply with the scheduled power to be sent by charging and discharging the storage battery, it is necessary to accurately predict the amount of power generated by the solar cells at each power generation base. Furthermore, it is necessary to accurately predict the power demand at the demand base.

[0010] The extent to which the power demand at a demand base fluctuates depends on the characteristics of the demand base. When transmitting wheeled power to a demand base where the power demand fluctuates greatly, a demand imbalance is likely to occur. Therefore, when transmitting power from a power generation system to multiple demand bases, it is desirable to consider the possibility of a demand imbalance occurring at each demand base and to avoid this as much as possible. In conventional power interchange systems such as those in Patent Documents 1 and 2, there has been no sufficient consideration of how to avoid such demand imbalance at multiple demand bases.

[0011] The present invention has been made in consideration of the above-mentioned problems, and aims to suppress demand imbalance that occurs when transmitting power to multiple demand bases in a power interchange system that transmits power from a power generation system composed of solar cells. [Means for solving the problem]

[0012] The power interchange system of the present invention calculates the power to be transmitted from the power generation system to the demand base by aggregating the amount of power generated at multiple power generation bases and the power demand at multiple demand bases, and determines the destination of the transmitted power so that power is transmitted with highest priority to the demand base with the smallest fluctuation in power demand over time. Effect of the Invention

[0013] According to the power interchange system of the present invention, in a power interchange system that transmits power from a power generation system configured with solar cells, it is possible to suppress a demand imbalance that occurs when transmitting power to a plurality of demand bases. Problems, configurations, effects, etc. other than those described above will become clear from the description of the embodiments below. [Brief description of the drawings]

[0014] [Figure 1A] 1 is a configuration example of a power generation system provided by a business operator that performs self-wheeling. [Figure 1B] 1 is a configuration example of a power generation system provided by a business operator that performs self-wheeling. [Diagram 2] 1 is a configuration diagram of a power interchange system according to a first embodiment. [Diagram 3] FIG. 2 is a schematic diagram showing the relationship between the amount of power generated by solar cells and the wheeling planned power. [Figure 4] FIG. 2 is a schematic diagram illustrating power transmission priority for a demand base. [Diagram 5] FIG. 13 is a schematic diagram illustrating another application of surplus generated electricity. [Figure 6] FIG. 13 is a schematic diagram illustrating another application of surplus generated electricity. [Figure 7] FIG. 13 is a schematic diagram illustrating another application of surplus generated electricity. [Figure 8] FIG. 11 is a configuration diagram of a power interchange system according to a second embodiment. [Figure 9] FIG. 11 is a configuration diagram of a power interchange system according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] <Embodiment 1> 1A and 1B show an example of the configuration of a power generation system provided by a business operator that performs self-wheeling. The power generation system is composed of a solar cell (PV) and a storage battery. The solar cell is connected to a power grid via a DCDC converter and a DCAC converter. The storage battery is connected in the same way. A power control device 1 controls the operation of the solar cell and the storage battery by transmitting operation commands to a drive device for the solar cell and a drive device for the storage battery (each of which is composed of the above converter). There may be multiple solar cells and multiple storage batteries installed.

[0016] FIG. 2 is a configuration diagram of a power interchange system according to a first embodiment of the present invention. Power generated at bases 1 to 3 is transmitted to bases A and B via a power grid (power transmission network). Bases 1 to 3 may have the same configuration or may have different configurations. Bases A and B are demand bases. The power control device 1 controls the transmitted power based on demand forecast data and measurement data of each facility, according to a procedure to be described later. The power control device 1 includes a calculation unit 11 and a storage unit 12. These will be described later.

[0017] Of the power generation bases, base 1 is the parent base, and the other power generation bases are child bases. A power interchange plan for the entire power generation bases is formulated at the parent base. Therefore, a power control device 1 is installed at the parent base. The power control device 1 executes charge / discharge commands to the storage battery at the parent base (if the other bases are equipped with storage batteries, it issues charge / discharge commands to those batteries) and output commands to the solar cells at each base. In this way, the power interchange system shown in Figure 2 controls the power transmitted to the demand base.

[0018] Figure 3 is a schematic diagram showing the relationship between the amount of power generated by solar cells and the planned transmission power. In principle, the power scheduled for transmission (planned transmission power) is covered by the amount of power generated by solar cells. When the amount of power generated by solar cells and the planned transmission power are each added together for one day, a surplus may be generated, as shown in Figure 3. This surplus can be distributed for use by time period, for example, as follows:

[0019] (1) During the day, surplus power generated by the solar panels is charged into the storage battery in preparation for a power generation shortage the next day. If the power generated by the solar panels is insufficient the next day, the storage battery is discharged to cover the planned power for wheeling. (2) In the evening, surplus electricity generated by solar panels is sold. While electricity demand tends to rise in the evening, the amount of electricity generated by solar panels falls, making it easy for shortage imbalances to occur in the evening. As a result, imbalance penalty fees tend to rise in the evening, and the electricity selling price also tends to rise. In addition, transmission companies generally try to minimize the discrepancy between the scheduled transmission power and the transmission planned power at the end of the day, so electricity market prices tend to rise in the evening. Therefore, surplus electricity generated in the evening is sold. (3) At night, surplus electricity generated by the solar panels is consumed at the power generation site without being transported from the power generation site.

[0020] FIG. 4 is a schematic diagram for explaining the power transmission priority for demand bases. There are various types of demand bases, ranging from those with large fluctuations in power demand over time to those with small fluctuations. The magnitude of the fluctuation in power demand over time is roughly determined by the nature of the demand base. It is assumed that a demand base with small demand fluctuations is less likely to cause a demand imbalance. On the other hand, if power is transmitted preferentially to a demand base with large demand fluctuations, there is a high possibility that either a surplus imbalance or a shortage imbalance will occur. Therefore, in the present invention, in order to suppress the demand imbalance as much as possible, it is considered that it is desirable to transmit power preferentially to a demand base with small fluctuations in power demand over time.

[0021] Of the demand bases to which power is transmitted from the power generation system, it is desirable to transmit power with the highest priority to the demand base with the smallest fluctuation in power demand over time. Then, the demand base with the next smallest fluctuation in demand may be selected as the next power transmission destination, and this process may be repeated until the power generation capacity is exhausted. As a result, the base with the largest fluctuation in demand is assigned a smaller amount of transmitted power, so that at least the possibility of causing surplus imbalance is reduced. This makes it possible to effectively suppress demand imbalance (especially surplus imbalance). The calculation unit 11 determines the destination of power transmission from the power generation system according to the above procedure.

[0022] FIG. 5 is a schematic diagram for explaining another use of surplus power generation. As explained in FIG. 3, surplus power generation by solar cells can be charged to a storage battery. This charged power can be used to make up for a power generation shortage at another power generation base. For example, assume that surplus power generation by solar cells occurs at base 1 as in FIG. 3. This surplus power generation is charged to a storage battery. Since base 2 was scheduled to generate the same amount of power as base 1, the transmission planned power was also about the same as base 1, but it is assumed that the actual power generation was less than planned. The shortage can be made up by discharging the charged storage battery at base 1. As a result, the aggregate of bases 1 to 2 can meet the transmission planned power.

[0023] Fig. 6 is a schematic diagram for explaining another use of surplus power generation. In Fig. 6, base 1 and base 2 are both power generation bases equipped with solar cells and storage batteries. It is assumed that the nighttime power demand at base 2 is smaller than the nighttime power demand at base 1. In this case, the self-consumption power consumption at night explained in Fig. 3 will be less at base 2, so it is conceivable to send the power instead of self-consumption. However, the following points should be taken into consideration.

[0024] As explained in FIG. 4, when the power transmission destination is determined in order of the demand base with the least fluctuation in power demand over time, the demand base with the greatest demand fluctuation (base A in FIG. 6) is the last to remain. When power is transmitted to a demand base with a large demand fluctuation, there is a high possibility that a demand imbalance (especially a surplus imbalance) will occur. Therefore, the smallest demand value among the predicted values ​​of the power demand that fluctuates over time at the bases with the largest demand fluctuation is identified, and the amount of power to be transmitted to the base is determined so as not to exceed the smallest predicted demand value. In this example, the amount of discharge to be discharged from the storage battery at base 2 is determined. The calculation unit 11 determines the power transmission destination and the transmitted power using the above procedure. As a result, when transmitting power from a power generation base with small nighttime power consumption, it is possible to suppress a demand imbalance at a demand base with a large demand fluctuation.

[0025] Fig. 7 is a schematic diagram explaining another use of surplus power generation. Some power generation bases do not install stationary storage batteries, but only portable storage batteries. In Fig. 7, base 2 corresponds to this. Base 2 does not use storage batteries as a rule, and power storage is only possible when a portable storage battery is present within base 2. Therefore, if base 2 generates the same amount of power from solar cells as base 1, it can use more power as wheeled power than base 1. Power that remains surplus after being allocated to wheeled power is sold or self-consumed. Fig. 7 shows these.

[0026] <Embodiment 2> FIG. 8 is a configuration diagram of a power interchange system according to a second embodiment of the present invention. In the second embodiment, an aggregate consisting of one or more power generation bases and one or more demand bases is defined as a sector. The power control device 1 (as well as the calculation unit 11 and the storage unit 12) can control the self-dispatch of each of the multiple sectors. In this case, information such as demand forecast data, weather forecast data, and each measurement data in each sector is aggregated in the power control device 1. The power control device 1 uses this data to control the self-dispatch of each sector. Each sector may be controlled individually (i.e., the operation of each sector does not affect the operation of the other sectors), or the aggregate of the sectors may be controlled by regarding it as a new single sector.

[0027] As a criterion for selecting sectors to be aggregated by the power control device 1, for example, a sector with large demand fluctuation (a sector where the fluctuation over time of power demand is equal to or greater than a threshold) and a sector with small demand fluctuation (a sector where the fluctuation over time of power demand is less than the threshold) are coupled and these sectors are aggregated as control targets. By aggregating multiple sectors, the power interchange system as a collection of these sectors can be optimized overall.

[0028] Each sector may be equipped with a portable battery. Examples of the portable battery include a removable modular battery and a battery mounted on an electric vehicle. It is desirable to transport power between coupled sectors using a portable battery, thereby reducing the number of stationary batteries, because the cost of installing stationary batteries is generally high. If the portable battery is transported to a power generation site where surplus power generation is expected to occur, the wheeling plan can be met without wasting the surplus power generation, even without installing a stationary battery.

[0029] The magnitude of fluctuation in power demand over time varies for each coupled sector. It is desirable to place more portable batteries in sectors with large demand fluctuations and fewer in sectors with small demand fluctuations. This makes it possible to more reliably suppress imbalances in sectors with large demand fluctuations. This is because the portable batteries can be charged when power demand is smaller than planned, and the charged power can be discharged when demand is larger than planned.

[0030] <Embodiment 3> FIG. 9 is a configuration diagram of a power interchange system according to a third embodiment of the present invention. A plurality of electricity retailers (wheeling companies in the present invention) may form a single group, and one of the companies may collectively manage the group and enter into a contract with a power company. Such a group is called a balancing group. In a balancing group, it is assumed that the companies constituting the group will support each other by aggregating and managing the power supply and demand within the group. Therefore, in FIG. 9, the power control device 1 collectively controls the power interchange systems owned by each company in the balancing group.

[0031] The sectors of each business operator may have any configuration. In Fig. 9, business operator 1 has multiple sectors as described in the second embodiment, and business operator 2 has a single sector. The power control device 1 collects information such as demand forecast data, weather forecast data, and each measurement data from each base of each business operator, and uses this information to control the power interchange system of each business operator.

[0032] <Modifications of the present invention> The present invention is not limited to the above-described embodiment, and includes various modified examples. For example, the above-described embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to those having all of the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0033] 1: Power control device 11: Arithmetic section 12: Storage part

Claims

1. A power interchange system in which power generated by a first power generation system constituted by a solar cell is transmitted between bases via a power transmission network, The first power generation system is configured by a first solar cell included in a first power generation base and a second solar cell included in a second power generation base, The power interchange system includes a calculation unit that determines power to be transmitted between the bases, the calculation unit calculates transmission power to be transmitted from the first power generation system to a demand base by aggregating the power consumption at each of the bases, the power generation amount at the first power generation base, and the power generation amount at the second power generation base; The calculation unit determines a destination of the transmitted power so as to transmit power with the highest priority to a demand base where the fluctuation over time of the power demand is the smallest. The power interchange system is characterized by:

2. The first power generation base has a first storage battery, The first storage battery is charged with surplus power generated by the first solar cell, The calculation unit acquires a planned power that the first power generation system is scheduled to output to the power transmission network, When the power generated by the second solar cell is not sufficient to satisfy the planned power, the calculation unit discharges the first storage battery to make up for the shortage, thereby controlling the first storage battery so that the assembly of the first power generation base and the second power generation base satisfies the planned power.

2. The power interchange system according to claim 1 .

3. The second power generation base is a base having a smaller power demand at night than the first power generation base, The second power generation base has a second storage battery, The calculation unit identifies a demand fluctuation location among the demand locations where a time-dependent fluctuation in power demand is equal to or greater than a threshold value, The calculation unit acquires a minimum demand forecast value that is the smallest among forecast values ​​of power demand that fluctuates over time at the demand fluctuation base, The calculation unit controls a discharge amount from the second storage battery so that power transmitted from the first power generation system to the demand fluctuation base does not exceed the minimum demand forecast value.

2. The power interchange system according to claim 1 .

4. The second power generation base does not have a stationary storage battery, The calculation unit consumes surplus power at the second power generation base by outputting surplus power generated by the second solar cell to the power transmission network; When a surplus still remains even after the surplus power of the second solar cell is output to the power transmission network, the calculation unit sells the surplus power.

2. The power interchange system according to claim 1 .

5. The power interchange system further includes a second power generation system configured with a solar cell, the first power generation system is configured to transmit power to a first demand base, and the second power generation system is configured to transmit power to a second demand base, The first demand base is a base where the fluctuation over time of the power demand is equal to or greater than a reference value, The second demand base is a base where the fluctuation over time of the power demand is less than the reference value, The calculation unit determines transmission power to be transmitted from each of the first power generation system and the second power generation system to each of the demand bases.

2. The power interchange system according to claim 1 .

6. the first power generation system and the second power generation system each have a portable storage battery; the number of portable storage batteries included in the first power generation system is greater than the number of portable storage batteries included in the second power generation system; The calculation unit determines the transmission power so as to supply power to at least one of the first demand base or the second demand base by using at least one of portable storage batteries respectively provided in the first power generation system and the second power generation system.

6. The power interchange system according to claim 5.

7. the first power generation system is provided by a first operator, The calculation unit acquires data describing power demand and power generation amount in an entire balancing group composed of the first business operator and the second business operator, The calculation unit mutually accommodates electric power between the first business operator and the second business operator in accordance with the electric power demand and the amount of electric power generated in the entire balancing group described in the data.

2. The power interchange system according to claim 1 .

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