Power system

Abstract

To provide a power system capable of performing control considering demand values in power control using induction command values.SOLUTION: A power system S1 includes a processing device A1 including a target setting unit 13 that sets a system target value and a command value calculation unit 14 that calculates an induced command value, and a plurality of power control devices B1 that controls the output power of power equipment X on the basis of a common induced command value calculated by the processing device A1. The target setting unit 13 includes a storage unit 131 storing set target values, a demand prediction unit 132 that estimates predicted demand, a demand difference determination unit 133 that determines whether a demand difference prediction exists where a demand difference exists between the predicted demand and the target demand, and a target change unit 134 that changes the system target value in a direction that reduces the demand difference when a demand difference prediction exists. The command value calculation unit 14 calculates the guidance command value using the modified target value changed by the target change unit 134 when a demand discrepancy prediction occurs.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a power system that controls a value of a node power at a node with a power grid to a system target value. [Background technology]

[0002] Power systems that manage multiple power devices connected to a power grid and control power transmission and reception from the power grid are becoming more common. For example, Patent Documents 1 and 2 disclose conventional power systems. In the power system described in Patent Document 1, a processing device calculates an induction command value for controlling power at a connection point with the power grid (connection point power) to a target power. Each power control device controls output power in a distributed manner using the induction command value calculated by the processing device. At this time, each power control device calculates a target value for output power based on an optimization problem using the induction command value. Then, the output power is controlled so that the output power reaches the target value. In this manner, energy management of the power system is performed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-150690 [Patent Document 2] Japanese Patent Application Publication No. 2018-170901 Summary of the Invention [Problem to be solved by the invention]

[0004] When receiving power from the power grid, the power system manager must pay an electricity fee to the power company. This electricity fee includes a basic fee and a metered fee. The basic fee is determined by the maximum value (peak value) of the power usage (demand value) recorded, for example, every 30 minutes, by a power meter installed at the connection point. Specifically, the basic fee is higher when the peak value of power usage is high, and lower when the peak value of power usage is low.

[0005] If the peak value of power usage rises even once, the annual base rate will be set high. Therefore, if you want to keep your power rates to a minimum, you need to keep the peak value of power usage (demand value) low. Meanwhile, since the base rate for electricity is determined by the peak value of power usage, during a demand time period when the demand value is below the peak value, the base rate for electricity does not increase even if power is received from the power grid as long as it does not exceed the peak value. The power systems described in Patent Documents 1 and 2 perform instantaneous power control based on the target power, but do not perform power control that takes the demand value into consideration. As a result, they are unable to respond to changes in power equipment during the demand time period, which can result in the peak value being exceeded or ineffective use of power up to the peak value.

[0006] The present disclosure has been devised in consideration of the above circumstances, and its purpose is to provide a power system that is capable of performing control that takes into account demand values ​​when controlling power using induction command values. [Means for solving the problem]

[0007] The power system provided by the present disclosure is a power system that controls a value of a connection point power at a connection point with a power grid to a system target value, and includes a processing device including a target setting unit that sets the system target value and a command value calculation unit that calculates an induction command value for setting the value of the connection point power to the system target value, and a plurality of power control devices each connected to a power device, and controlling the output power of the corresponding power device based on the common induction command value calculated by the processing device, and the target setting unit stores a set target value that is the system target value, a demand prediction unit that estimates a predicted demand, which is a predicted value of the power demand at the end of the current demand time limit; a demand difference determination unit that determines whether or not the prediction is a demand difference prediction in which there is a demand difference between the predicted demand and a target demand; and a target change unit that, if the prediction is a demand difference prediction, changes the system target value in a direction in which the demand difference becomes smaller, and the command value calculation unit calculates the induced command value using a changed target value, which is the system target value changed by the target change unit, at the time of the demand difference prediction.

[0008] In a preferred embodiment of the power system, the demand prediction unit estimates the predicted demand using the amount of power already received from the power grid in the current demand time period and the current value of the connection point power.

[0009] In a preferred embodiment of the power system, the target change unit takes into account the remaining time in the current demand time period when changing the system target value from the set target value to the changed target value.

[0010] In a preferred embodiment of the power system, the target change unit calculates the change target value by calculation of the following equation (1). Change target value = Set target value - (Predicted demand - Target demand) × Set time of demand period × Coefficient / Remaining time (1)

[0011] In a preferred embodiment of the power system, when the demand difference is caused by a demand excess where the predicted demand exceeds the target demand, the demand discrepancy determination unit determines that the demand discrepancy prediction is a demand excess prediction, and when the demand excess prediction is determined, the target change unit changes the system target value in a direction that will eliminate the demand excess.

[0012] In a preferred embodiment of the power system, when the demand difference is caused by a demand surplus in which the predicted demand is lower than the target demand, the demand discrepancy determination unit determines that the demand discrepancy prediction is a demand surplus prediction, and when the demand surplus prediction is a demand surplus prediction, the target change unit changes the system target value in a direction that eliminates the demand surplus. [Effects of the Invention]

[0013] According to the power system of the present disclosure, when a demand difference is predicted between the power demand at the end of the current demand time period and the target demand (i.e., a demand difference prediction), the system target value is changed from the set target value to a changed target value for reducing the demand difference. As a result, in the power system of the present disclosure, when a difference is predicted between the power demand and the target demand, the system target value is automatically changed, making it possible to control the power demand to the target demand in response to changes in the power equipment during the demand time period (for example, to prevent the power demand from exceeding the peak value or to effectively utilize power up to the peak value of the power demand). In other words, the power system of the present disclosure makes it possible to perform power control using an induced command value while taking the demand value into consideration. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram illustrating an overall configuration of a power system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a detailed configuration example of a power system according to an embodiment. [Figure 3] FIG. 10 is a diagram illustrating a simulation result of power control performed by a power system according to an embodiment. [Figure 4] FIG. 10 is a diagram illustrating another simulation result of power control performed by a power system according to an embodiment. [Figure 5] FIG. 10 is a diagram showing a simulation result of power control performed by a power system according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the power system of the present disclosure will be described below with reference to the accompanying drawings. In the following, identical or similar components will be designated by the same reference numerals, and redundant description will be omitted.

[0016] 1 and 2 show a power system S1 according to one embodiment. As shown in Fig. 1 and 2, the power system S1 includes a processing device A1, a plurality of power control devices B1, and a power receiving facility C1.

[0017] The power system S1 is connected to the power system D via a connection point Y. The power system S1 can receive power from the power system D. The power system S1 may also be capable of transmitting power to the power system D (capable of reverse power flow). In the present disclosure, when the power system S1 is outputting power to the power system D, i.e., when reverse power flow is occurring, the connection point power is assumed to have a negative value. On the other hand, when power is output from the power system D to the power system S1 (when the power system S1 is receiving power from the power system D), the connection point power is assumed to have a positive value. The connection point power refers to the power at the connection point Y between the power system S1 and the power system D.

[0018] In the power system S1, the processing device A1 and multiple power control devices B1 cooperate to perform power control so that the magnitude of the node power becomes a system target value. The system target value is a target value of the node power. In the power control of the power system S1, the processing device A1 calculates a induced command value pr for controlling the value of the node power to the system target value. Each power control device B1 calculates a target value of the output power (an equipment target, described later) based on the induced command value pr calculated by the processing device A1. Each power control device B1 then controls the output power based on the calculated equipment target. In this way, the power system S1 controls the value of the node power to the system target value by the multiple power control devices B1 controlling the output power in a decentralized manner. The induced command value pr is used by each power control device B1 to calculate the equipment target and is common to the multiple power control devices B1. Power control performed by the power system S1 includes, for example, output suppression control, peak cutting control, reverse power flow avoidance control, and schedule control. Output reduction control reduces the power (power sold) output from the power system S1 to the power system D in accordance with an output reduction command issued by the power company. Peak cut control reduces the peak value of the power (power purchased) supplied from the power system D. Reverse flow avoidance control suppresses the occurrence of reverse flow. Schedule control sets the output power of the power system S1 to a power value set by the administrator. The power system S1 performs one of these power controls using a system target value according to the control mode set in the processing device A1.

[0019] The power loads L are supplied with power from the power system D or multiple power control devices B1 and consume the supplied power. In the illustrated example, the power system S1 includes one power load L, but may include multiple power loads L. The power loads L include either or both of general loads and important loads. General loads are, for example, electrical equipment that is relatively less affected even if power is cut off during a disaster, such as air conditioning equipment. Important loads are important loads that require a continuous supply of power even during a disaster, such as emergency elevators, electrical equipment that requires continuous operation, and building lighting (emergency lighting). Note that the general loads and important loads are not limited to these examples.

[0020] The power lines 90 constitute a power network in the power system S1. The power system S1 is connected to a power grid D by the power lines 90. In the illustrated example, the power lines 90 include one that connects the power grid D to a power receiving facility C1, one that connects the power receiving facility C1 to a power load L, one that connects the power receiving facility C1 to each power control device B1, and one that connects each power control device B1 to a corresponding power device X.

[0021] The power receiving equipment C1 is configured to include a distribution board and a power distribution panel. The power receiving equipment C1 may also include various protection devices for connecting the power system S1 to the power grid D. The power receiving equipment C1 receives power input via power lines 90 from the power grid D, each of the multiple power control devices B1, and the power load L. The power receiving equipment C1 supplies the received power to the power grid D, the multiple power control devices B1, the power load L, etc. The power receiving equipment C1 is capable of communicating with the processing device A1.

[0022] As shown in Fig. 2, the power receiving facility C1 includes a measurement unit 31 and a communication unit 32. The measurement unit 31 is connected to a connection point Y between the power system S1 and the power grid D, and detects the connection point power. The measurement unit 31 is, for example, a power transducer. The communication unit 32 transmits the measurement result of the measurement unit 31, i.e., the measurement value of the connection point power, to the processing device A1.

[0023] The processing device A1 can communicate with each of the multiple power control devices B1 and the power receiving device C1. This communication may be wireless or wired. The processing device A1 monitors the connection point power and calculates an induction command value pr for controlling the connection point power value to a system target value. In this embodiment, the connection point power value is measured by the power receiving device C1. However, unlike this example, the connection point power value may be an estimated value. The processing device A1 may acquire each output power value from each power control device B1 and also acquire a power consumption value from the power load L, and calculate an estimated value using the acquired output power value and the acquired power consumption value. The processing device A1 may also switch the connection point power value between a measured value and an estimated value depending on the control mode being set. As shown in FIG. 2, the processing device A1 includes an acquisition unit 11, an acquisition unit 12, a target setting unit 13, a command value calculation unit 14, a receiving unit 15, and a transmitting unit 16.

[0024] The acquisition unit 11 acquires the value of the node power. In this embodiment, the acquisition unit 11 acquires the value of the node power by receiving a measurement value of the node power from the power receiving facility C1 via the receiving unit 15.

[0025] The acquisition unit 12 acquires a system target value according to the control mode set in the processing device A1. The acquired system target value is the same as the target power in Patent Documents 1 and 2. For example, the acquisition unit 12 acquires the system target value by receiving the system target value via the receiving unit 15 from a computer (not shown) of a power company or a computer (not shown) that inputs settings of the processing device A1. The acquisition unit 12 outputs the acquired system target value to the target setting unit 13.

[0026] The target setting unit 13 sets a system target value, which is a target value for the connection point power. The target setting unit 13 stores the system target value acquired by the acquisition unit 12 as a set target value. In this embodiment, when the peak cut control is set, the target setting unit 13 predicts the power demand at the end of the current demand time limit. The demand time limit may be, for example, 30 minutes, but is not limited to this. For example, it may be 15 minutes or 1 hour. If the predicted power demand exceeds a preset target demand, the target setting unit 13 changes the system target value and outputs the changed system target value to the command value calculation unit 14. As shown in FIG. 2 , the target setting unit 13 includes a memory unit 131, a demand prediction unit 132, a demand discrepancy determination unit 133, and a target change unit 134 as functional components for this peak cut control. These may be configured, for example, by at least one CPU (Central Processing Unit) and at least one memory connected by bus communication (CAN: Controller Area Network), but are not limited to being configured by a CPU and a memory.

[0027] The storage unit 131 stores the system target value input from the acquisition unit 12 as a set target value.

[0028] The demand prediction unit 132 estimates a predicted value of the power demand (predicted demand) at the end of the current demand time limit. For example, the demand prediction unit 132 predicts the predicted demand as follows. The demand prediction unit 132 receives a node power value from the acquisition unit 11. The demand prediction unit 132 calculates the actual demand up to the present time in the current demand time limit using the node power value. In other words, the demand prediction unit 132 calculates the amount of power already received from the power grid D in the current demand time limit. Then, the demand prediction unit 132 adds the actual demand to the amount of power that would be received if the current node power value were to continue for the remaining time of the current demand time limit, and calculates the average power usage for the demand time limit (30 minutes in this embodiment), thereby estimating the power demand at the end of the current demand time limit. In this way, the demand prediction unit 132 estimates the predicted demand. As described above, the predicted demand is, for example, the average value of power (average demand) during the demand time period, but it may also be the accumulated amount of power (accumulated demand) during the demand time period. Note that the average demand is used to calculate the electricity rate (basic charge) by the electric power company. Note that the prediction method for the predicted demand is not limited in any way, and any well-known prediction method may be used. The demand prediction unit 132 outputs the predicted demand to the demand discrepancy determination unit 133 and the target change unit 134.

[0029] The demand discrepancy determination unit 133 determines whether or not the demand discrepancy prediction is a demand discrepancy prediction in which there is a difference between the predicted demand and the target demand (hereinafter referred to as a "demand discrepancy prediction"). In this embodiment, the demand discrepancy determination unit 133 determines whether or not the demand discrepancy prediction is a demand excess prediction in which the predicted demand exceeds the target demand. For example, the demand discrepancy determination unit 133 determines whether or not the demand is a demand excess prediction as follows: the demand discrepancy determination unit 133 compares the predicted demand predicted by the demand prediction unit 132 with a preset target demand. Then, if the comparison result shows that the predicted demand is greater than the target demand, the demand discrepancy determination unit 133 determines that the demand is a demand excess prediction (demand discrepancy prediction). On the other hand, if the predicted demand is equal to or less than the target demand, the demand discrepancy determination unit 133 determines that the demand is not a demand excess prediction (not a demand discrepancy prediction). The target demand may be set to, for example, the same value as the set target value in peak cut control, but may be configured to be changeable to any value by an administrator's operation. The demand discrepancy determination unit 133 outputs a determination result (hereinafter referred to as "discrepancy determination result") as to whether or not there is a demand excess prediction (demand discrepancy prediction) to the target change unit 134. In the present disclosure, demand excess refers to a state in which the power demand at the end of the current demand time limit exceeds the target demand.

[0030] The target change unit 134 receives the predicted demand from the demand prediction unit 132 and also receives the discrepancy determination result from the demand discrepancy determination unit 133. The target change unit 134 changes the system target value from the set target value to a changed target value according to the input discrepancy determination result. For example, the target change unit 134 changes the system target value as follows. That is, the target change unit 134 reads out the set target value stored in the storage unit 131. When the discrepancy determination result is a demand discrepancy prediction, the target change unit 134 changes the system target value in a direction that reduces the demand difference, for example, by performing the calculation of the following equation (2). In the following equation (2), the remaining time is the remaining time in the current demand time limit. The set time of the demand time limit is used in the same units as the remaining time. In an example of a 30-minute demand, the set time of the demand time limit is 1800 (= 30 minutes × 60 seconds) if the set unit of the remaining time is "seconds," and 30 (= 30 minutes × 1 minute) if the set unit of the remaining time is "minutes." The coefficient is a weight for adjusting the amount of change from the set target value based on the demand excess. The coefficient may be set to a value of 1 or greater, for example, 2. Note that, considering that the coefficient changes the amount of change in the change target value relative to the set target value, it is preferable that the coefficient be 3 or less. In this embodiment, the determination result of whether or not there is a demand excess prediction is input as the discrepancy determination result, and if the discrepancy determination result is a demand excess prediction, the target change unit 134 changes the system target value in a direction that resolves the demand excess. The direction in which the demand excess is resolved is the direction in which the received power from the power system D is reduced, which corresponds to the direction in which the value of the connection point power is reduced in this embodiment (a configuration in which the node power is a positive value when the power system S1 receives power from the power system D). When the discrepancy determination result is a demand excess prediction (demand discrepancy prediction), the target change unit 134 outputs the calculated changed target value as the system target value to the command value calculation unit 14. On the other hand, when the discrepancy determination result is not a demand excess prediction (demand discrepancy prediction), the target change unit 134 does not change the system target value, and outputs the set target value as the system target value to the command value calculation unit 14.The method of changing to the changed target value by the target changing unit 134 (method of calculating the changed target value) is not limited to the above example (not limited to the calculation of the following equation (2)). Change target value = Set target value - (Predicted demand - Target demand) × Set time of demand period × Coefficient / Remaining time (2)

[0031] The command value calculation unit 14 calculates the induction command value pr using the node power value acquired by the acquisition unit 11 and the system target value (set target value or changed target value) set by the target setting unit 13. The calculation method of the induction command value pr is the same as that of the power system described in Patent Document 1. For example, the command value calculation unit 14 calculates the induction command value pr by solving the state equations (simultaneous differential equations) shown in the following equations (3) and (4). In the following equations (3) and (4), P(t) is the node power, Pc(t) is the system target value, λ(t) is a state variable, pr(t) is the induction command value, and ε is a gradient coefficient. Note that in the power system S1 disclosed herein, the node power is set to a negative value during reverse power flow, and therefore the node power P(t) and the system target value Pc(t) are reversed between positive and negative, compared to the configurations described in Patent Documents 1 and 2. This state equation is set in the command value calculation unit 14. The command value calculation unit 14 calculates the induction command value every predetermined time (for example, 1 [sec]). The induction command value calculated by the command value calculation unit 14 is transmitted to each power control device B1. Note that the command value calculation unit 14 may use a difference equation obtained by discretizing the state equations shown in the following equation (3) and the above equation (4) instead of the state equations. The difference equation is the same as that of the power system described in Patent Document 1.

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[0032] The receiver 15 receives a measurement value of the connection point power from the power receiving equipment C1 through communication with the power receiving equipment C1. The receiver 15 also receives a system target value from the computer described above. The transmitter 16 transmits the induction command value calculated by the command value calculator 14 through communication with the multiple power control devices B1. The transmitter 16 transmits the induction command value to the multiple power control devices B1 by, for example, multicast, but may also transmit by broadcast (simultaneous transmission) or unicast.

[0033] Each of the multiple power control devices B1 is connected to an electric power device X. Each power control device B1 controls the output of the connected electric power device X. Each of the multiple power control devices B1 is capable of communicating with a processing device A1. As in the power system described in Patent Document 1, the electric power device X is, for example, a solar cell, a storage battery, an electric vehicle, or a generator. In the power system S1, each of the multiple power control devices B1 is a solar power conditioner, a storage battery power conditioner, an EV (Electric Vehicle) stand, or a generator control device. For example, all of the multiple power control devices B1 may be solar power conditioners or storage battery power conditioners. Furthermore, the multiple power control devices B1 may be configured with at least one solar power conditioner and at least one storage battery power conditioner. In other words, the multiple power control devices B1 may include any one of a solar power conditioner, a storage battery power conditioner, an EV stand, or a generator control device. The solar power conditioner is connected to a solar cell as the power device X and controls the power generated by the solar cell. The storage battery power conditioner is connected to a storage battery as the power device X and controls the charging and discharging of the storage battery. The EV stand is connected to an electric vehicle as the power device X and controls the charging and discharging of the electric vehicle. The generator control device is connected to a generator as the power device X and controls the power generated by the generator. The multiple power control devices B1 may also include a load control device that uses a power load L as the power device X, similar to the power system described in Patent Document 1.

[0034] As shown in FIG. 2, each of the plurality of power control devices B1 includes a receiving unit 21, a target calculation unit 22, and a power control unit .

[0035] The receiving unit 21 receives the guidance command value pr transmitted from the processing device A1. The receiving unit 21 outputs the received guidance command value pr to the target calculation unit 22.

[0036] The target calculation unit 22 calculates the target value of the output of the corresponding power device X (hereinafter referred to as the device target P ref The induction command value pr is calculated based on the equipment target P ref This optimization problem includes an evaluation function and constraint conditions. The evaluation function is the same as that described in Patent Document 1, for example. For example, the target calculation unit 22 performs the calculations of the following equations (5) and (6) derived from the evaluation function, as described in Patent Document 1. In the following equations (5) and (6), pr lmt is the induction command limit, and a1 to a4 are the design parameters. lmt and design parameters a1 to a4 are the same as those described in Patent Document 1. Then, as described in Patent Document 1, the calculation results are corrected by the constraint conditions to obtain the equipment target P ref The constraint conditions are the same as those described in Patent Document 1. Unlike these, the target calculation unit 22 calculates the equipment target P by solving the evaluation function under the constraint conditions. ref In the power system S1 of the present disclosure, the connection point power is set to a negative value during reverse power flow, and therefore, in the configurations described in Patent Documents 1 and 2, the device target P ref The device target P calculated by the target calculation unit 22 is reversed between positive and negative. ref is output to the power control unit 23.

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[0037] The power control unit 23 calculates the output power of the corresponding power device X (hereinafter referred to as "device power Pout ") is the equipment target P ref The power P of the power device X is calculated so that out For example, in the power control device B1 to which a solar cell is connected as the power device X, the power control unit 23 controls the device target P ref In the power control device B1 to which a storage battery is connected as the power device X, the power control unit 23 controls the power generated by the solar cell based on the device target P ref In the power control device B1 to which an electric vehicle is connected as the power device X, the power control unit 23 controls the charging power and discharging power of the storage battery based on the device target P ref In the power control device B1 to which a generator is connected as the power device X, the power control unit 23 controls the charging power and discharging power of the electric vehicle based on the device target P ref In a configuration in which a power control device B1 (load control device) using a power load L as a power device X is present, the power control unit 23 in the power control device B1 (load control device) controls the power generated by the generator based on the device target P ref The power consumption of the power load L is controlled based on the above.

[0038] In the power system S1 configured as above, each power control device B1 uses the induction command value pr received from the processing device A1 to set the device target P ref Then, each power control device B1 calculates the calculated device target P ref The power consumption of the device itself P out In this way, in the power system S1, the multiple power control devices B1 control the output power in a decentralized manner, so that the value of the connection point power becomes the system target value. In this embodiment, when calculating the induction command value pr for setting the value of the connection point power to the system target value in peak cut control, the processing device A1 determines whether there is a risk of exceeding the demand, that is, whether there is a demand excess prediction. Then, if there is a risk of exceeding the demand (if there is a demand excess prediction), the processing device A1 changes the system target value (set target value) that is set in advance. As a result, the system target value can be changed appropriately during the current demand time period.

[0039] Figure 3 shows simulation results for power control in power system S1. Figures 3(a) and 3(b) show simulation results for power system S1, and Figure 3(c) shows simulation results for a comparative power system. The comparative power system is configured to always use a set target value as the system target value (i.e., a configuration in which the system target value is not changed). The simulation results shown in Figures 3(a) to 3(c) show the changes in each power value over one demand time period. In each of Figures 3(a) to 3(c), the horizontal axis represents time and the vertical axis represents power. In each of Figures 3(a) to 3(c), the right diagram is an enlarged view of a portion of the left diagram (a range of 30 ± 2 kW). In Figure 3(a), the solid line represents the connection point power, the dashed line represents the set target value, and the dashed line represents the system target value. In Figure 3(b), the solid line represents power demand (average demand), the dashed line represents target demand, and the dashed line represents predicted demand. In FIG. 3(c), the solid line indicates the power demand (average demand), the dashed line indicates the target demand and the set target value, and the dashed line indicates the connection point power.

[0040] In the simulation shown in Fig. 3, the set target value and target demand are each set to 30 kW. In addition, in the simulation shown in Fig. 3, the power consumption of the power load L is set to 10 kW at the start and then changed to 70 kW at time t0 (i.e., the power consumption of the power load L is increased by +60 kW).

[0041] In the comparative power system, when the power consumption of the power load L changes at time t0 (10 kW → 70 kW: a change of +60 kW), the value of the node power instantaneously changes (30 kW → 90 kW: a change of +60 kW) as shown by the dashed line in Figure 3(c) due to factors such as the update period of the induction command value. This increase in the node power causes the power demand to increase by a larger amount than the increase up to time t0. Thereafter, the induction command value is updated, controlling the output power (device power) of each power control device B1, and the value of the node power becomes the system target value, which is the set target value (30 kW). However, due to the effect of the increase in power demand near time t0, the power demand exceeds the target demand at the end of the demand time limit (time te), as shown by the solid line in Figure 3(c).

[0042] Meanwhile, in the power system S1, when the power consumption of the power load L changes at time t0 (10 kW → 70 kW: +60 kW change), as in the comparative power system, the value of the node power instantaneously changes (30 kW → 90 kW: +60 kW change) as shown by the solid line in FIG. 3(a) due to the update period of the induction command value and other factors. Also, as in the comparative power system, this increase in the node power causes the power demand to increase more than the increase up to time t0, as shown by the solid line in FIG. 3(b). However, in the power system S1, this increase in power demand causes the predicted demand, shown by the dashed-dotted line, to change, as shown in FIG. 3(b), so that the predicted demand (dashed-dotted line) exceeds the target demand (dashed line). Therefore, the target setting unit 13 determines that the demand is over-predicted, and changes the system target value (dashed-dotted line) to a value (changed target value) smaller than the set target value (dashed line), as shown in FIG. 3(a). In other words, the node power is controlled to the changed target value rather than the set target value of 30 kW, and therefore becomes a value smaller than the set target value (30 kW). As a result, the increase in power demand becomes slightly more gradual, as shown by the solid line in Figure 3(b). This gradual increase in average demand causes the predicted demand to gradually decrease, and accordingly, the system target value (changed target value) also gradually approaches the set target value. After that, around time t1, when the power demand reaches the target demand, the node power is controlled to the system target value, which is the set target value (30 kW).

[0043] In the power system S1, the power demand is adjusted by changing the system target value according to the predicted demand, so that the power demand does not exceed the target demand at the end of the demand time limit (time te), as shown by the solid line in Figure 3(b). In other words, in the power system S1, when the predicted demand exceeds the target demand, the system target value is lowered (by changing from the set target value to the changed target value), slowing the increase in the power demand and controlling the power demand so that it does not exceed the target demand at the end of the demand time limit.

[0044] The simulation shown in Figure 3 shows the case where the power consumption of power load L is changed from 10 kW to 70 kW at time t0. However, in reality, the power consumption of power load L changes from moment to moment. Therefore, we simulated the change in integrated demand when the power consumption of power load L is changed as shown in Figure 4(b). Figure 4(a) shows the results of this simulation. In Figure 4(a), the solid line represents the connection point power, the dashed line represents the predicted demand, the dashed line represents the system target value, and the dashed line represents the power demand (average demand). In each of Figures 4(a) and (b), the horizontal axis represents time and the vertical axis represents power. In the simulation of Figure 4, as in the simulation of Figure 3, the set target value and target demand were set to 30 kW.

[0045] As shown in Figure 4(a), the predicted demand changes (as shown by the dashed line) in response to changes in the connection point power (as shown by the solid line), and the system target value is accordingly changed as shown by the dashed-dotted line. As a result, as shown by the two-dot-dash line in Figure 4(a), at the end of the current demand time period (time te), the power demand does not exceed the target demand. In other words, as can be seen from the simulation results shown in Figure 4, the power system S1 can prevent the power demand from exceeding the target demand even when the power consumption of the power load L changes from moment to moment.

[0046] The functions and effects of the power system S1 are as follows.

[0047] In the power system S1, the target setting unit 13 of the processing device A1 includes a demand prediction unit 132 that predicts a predicted demand, which is a predicted value of the power demand at the end of the current demand time period; a demand difference determination unit 133 that determines whether the demand difference prediction is a demand difference prediction in which there is a difference (demand difference) between the predicted demand and the target demand; and a target change unit 134 that changes the system target value in a direction to reduce the demand difference between the predicted demand and the target demand if the demand difference prediction is a demand difference prediction. The command value calculation unit 14 calculates an induced command value using a changed target value, which is the system target value changed by the target change unit 134, when the demand difference prediction is made. With this configuration, when a difference is predicted between the power demand in the current demand time period and the target demand, the system target value is changed in a direction to reduce the demand difference. This enables the power system S1 to perform power control using the induced command value, taking the demand value into consideration.

[0048] In particular, in the power system S1, the demand discrepancy determination unit 133 determines whether the predicted demand is a demand excess prediction, which indicates that the predicted demand exceeds the target demand, as a demand discrepancy prediction. If the predicted demand is a demand excess prediction, the target change unit 134 changes the system target value in a direction that eliminates the demand excess. This prevents the power demand at the end of the current demand time limit from exceeding the target demand. In a conventional power system (e.g., the photovoltaic power generation system PVS4 in Patent Document 2), when setting a peak cut target value (target power in peak cut control), it is possible to prevent the demand excess by setting a value that is a predetermined amount smaller than the upper limit desired by the administrator. However, while adding a margin to the peak cut target value increases the effectiveness of keeping the peak value of power consumption below the peak cut target value, there is a possibility that the amount of purchased power may be unnecessarily reduced. Therefore, the power system S1 can prevent the demand excess without adding a margin to the set target value.

[0049] In the power system S1, the demand prediction unit 132 estimates the predicted demand using the amount of power already received from the power system D during the current demand time period and the current value of the node power. With this configuration, the processing device A1 of the power system S1 can predict the power demand at the end of the current demand time period. Therefore, the power system S1 can determine (predict) whether the power demand will exceed the target demand during the current demand time period.

[0050] In the power system S1, the target change unit 134 takes into account the remaining time in the current demand time limit when changing the system target value from the set target value to the changed target value. With this configuration, the amount of power that needs to be adjusted to eliminate the demand excess (the amount of change from the set target value to the changed target value) changes depending on the remaining time in the current demand time limit. Therefore, as can be seen from the simulation results shown in FIG. 4, the power system S1 can more reliably suppress the demand excess even if a load fluctuation or the like occurs in the current demand time limit.

[0051] In the power system S1, the target change unit 134 calculates the changed target value by the calculation of the above formula (2). With this configuration, the processing device A1 of the power system S1 can change the system target value in a direction that resolves the demand excess.

[0052] In the above embodiment, the target change unit 134 may be configured not to change the system target value during a predetermined period from the start of the demand (for example, 5 to 15 minutes from the start), even if a demand excess is predicted. Alternatively, the demand prediction unit 132 may be configured not to calculate a predicted demand during a predetermined period from the start of the demand (for example, 5 to 15 minutes from the start). This is because, during the above-mentioned predetermined period from the start of the demand, there is still sufficient time remaining in the demand time limit, and therefore, there is a possibility that the demand discrepancy will be resolved within this remaining time even without changing the system target value.

[0053] In the above embodiment, the target change unit 134 may change the system target value using the above equation (2) regardless of the discrepancy determination result from the demand discrepancy determination unit 133. That is, in the power system disclosed herein, the target change unit 134 may change the system target value using the above equation (2) even when the discrepancy determination result is not a demand excess prediction. In this case, because the predicted demand does not exceed the set target value (target demand), the change target value is greater than the set target value. That is, the system target value is changed so as to increase the received power (within a range not exceeding the set target value). Note that in this example, the target setting unit 13 calculates the change target value using the above equation (2) every time a predicted demand is input from the demand prediction unit 132, and therefore does not need to include the demand discrepancy determination unit 133. Furthermore, the target change unit 134 may change the coefficients in the above equation (2) depending on the discrepancy determination result. For example, if the discrepancy determination result is not a demand excess prediction (if the predicted demand is smaller than the target demand), the target change unit 134 may reduce the coefficient of the above equation (2) (for example, less than 1).

[0054] In the above embodiment, the target change unit 134 takes into consideration the remaining time of the current demand time limit when changing the system target value to the change target value (i.e., when calculating the change target value), as can be seen from the above formula (2). Unlike this example, when calculating the change target value, the target change unit 134 may use a value obtained by subtracting a predetermined value from the set target value without taking into consideration the remaining time of the current demand time limit.

[0055] In the above embodiment, the demand discrepancy determination unit 133 determines whether the predicted demand is a demand excess prediction in which the predicted demand exceeds the target demand as the demand discrepancy prediction. Unlike this example, the demand discrepancy determination unit 133 may determine whether the predicted demand is a demand surplus prediction in which the predicted demand falls below the target demand, in addition to determining whether the demand discrepancy prediction is a demand excess prediction. That is, the demand discrepancy determination unit 133 may determine whether the demand discrepancy prediction is a demand excess prediction, a demand surplus prediction, or neither a demand excess prediction nor a demand surplus prediction (not a demand discrepancy prediction). Note that, in the present disclosure, a demand surplus refers to a state in which the power demand at the end of the current demand time limit falls below the target demand. In this modification, the demand discrepancy determination unit 133 determines that the comparison result between the predicted demand and the target demand is a demand excess prediction if the predicted demand is greater than the target demand, determines that the comparison result is a demand surplus prediction if the predicted demand is smaller than the target demand, and determines that the comparison result is neither a demand excess prediction nor a demand surplus prediction (not a demand discrepancy prediction) if the predicted demand is the same as the target demand. Then, the demand discrepancy determination unit 133 outputs the discrepancy determination result (determination result of whether the prediction is a demand excess prediction, a demand surplus prediction, or neither of these) to the target modification unit 134. If the discrepancy determination result is a demand excess prediction or a demand surplus prediction, the target modification unit 134 changes the system target value by calculating the above equation (2). Here, if the discrepancy determination result is a demand surplus prediction, the target modification unit 134 changes the system target value in a direction that eliminates the demand surplus. The direction in which the demand surplus is eliminated is the direction in which the received power from the power system D is increased, which corresponds to the direction in which the value of the connection point power is increased in this embodiment (a configuration in which the connection point power is a positive value when the power system S1 receives power from the power system D). This can be understood from the fact that in the demand surplus prediction, the predicted demand is smaller than the target demand, and therefore, according to the above formula (2), the changed target value becomes a value larger than the set target value.

[0056] FIG. 5 shows simulation results of power control in the power system of this modification, where the system target value is changed based on a demand surplus prediction. FIGS. 5(a) and 5(b) show simulation results for the power system S1 of this modification, and FIGS. 5(c) and 5(d) show simulation results for a comparative power system. The comparative power system is configured to always use a set target value as the system target value (i.e., a configuration in which the system target value is not changed). The simulation results shown in each of FIGS. 5(a) to 5(d) show changes in each power value during one demand time period. In each of FIGS. 5(a) to 5(d), the horizontal axis represents time and the vertical axis represents power. In each of FIGS. 5(a) to 5(d), the right diagram is an enlarged view of a portion of the left diagram. In FIGS. 5(a) and 5(c), the solid line represents the system target value, and the dashed line represents the set target value. In FIGS. 5(b) and 5(d), the solid line indicates the connection point power, the dashed line indicates the predicted demand, the one-dot chain line indicates the power demand (average demand), and the two-dot chain line indicates the target demand.

[0057] In the simulation shown in FIG. 5, the set target value and the target demand are each set to 100 kW. In the simulation shown in FIG. 5, only the power load L is connected from the start to time t0. At the subsequent time t0, for example, an electric vehicle (or a storage battery) is newly connected as the power device X, and charging of the electric vehicle (or the storage battery) begins. Here, the power consumption of the power load L is set to 70 kW during the demand time period. Therefore, in the simulation shown in FIG. 5, from the start to time t0, the received power (connection point power) from the power grid D is set to 70 kW, which is smaller than the set target value (target demand). After time t0, the power to be received from the power grid D increases due to charging of the newly connected electric vehicle (or storage battery). In the simulation shown in FIG. 5, from the start to time t1, the demand prediction unit 132 does not predict a predicted demand, and the system target value remains the set target value (is not changed).

[0058] In the comparative power system, the predicted demand falls below the target demand between time t1 and time t0, as shown in Figure 5(d), but the system target value remains at the set target value, as shown in Figure 5(c). After that, at time t0, the received power increases. At this time, due to factors such as the update period of the induction command value, the value of the node power momentarily increases, as shown by the solid line in Figure 5(d). However, the charging of the electric vehicle is controlled by updating the induction command value, and the value of the node power reaches the set target value (100 kW), which is the system target value. After that, the node power is controlled at the system target value (100 kW). However, because the received power up until time t0 was low, at the end of the demand time limit (time te), the power demand is approximately 15 kW lower than the target demand, as shown by the dashed-dotted line in Figure 5(d). In other words, there is a demand surplus during the current demand time limit.

[0059] On the other hand, in the power system S1 of this modification, at time t1, as shown in FIG. 5(b), the predicted demand is smaller than the target demand, and therefore the target setting unit 13 determines that the system is in a demand surplus prediction state. As a result, as shown in FIG. 5(a), the system target value (solid line) is changed to a value (changed target value) greater than the set target value (dashed line). However, until time t0, only the power load L is present, and the node power remains at 70 kW rather than the system target value. Therefore, the demand surplus prediction state continues until time t0. After that, at time t0, as in the comparative power system, the node power value momentarily rises as shown by the solid line in FIG. 5(b) due to the update period of the induced command value, but the charging of the electric vehicle is controlled by updating the induced command value. At this time, unlike the comparative power system, the system target value has been changed to a value greater than the set target value. Therefore, in the power system S1 of this modified example, the node power is controlled at a value greater than the set target value (100 kW), as shown in FIG. 5(b). After time t0, the target setting unit 13 sequentially changes the system target value to a changed target value based on the difference between the predicted demand and the target demand, and the node power is controlled by the changed system target value. Because the changed system target value is greater than the set target value, the difference between the predicted demand and the target demand gradually becomes smaller than in the comparative power system, as shown in FIG. 5(b). As a result, at the end of the demand time limit (time te), the power demand is approximately 5 kW lower than the target demand, as shown by the dashed-dotted line in FIG. 5(b). In other words, in the power system S1 of this modified example, the difference between the power demand and the target demand is smaller than in the comparative power system.

[0060] From the above, in the power system S1 of this modification, the power demand is adjusted by changing the system target value in accordance with the predicted demand, and as shown by the solid line in Figure 5(b), the difference between the power demand and the target demand can be reduced at the end of the demand time limit (time te). In other words, it can be seen that in the power system S1 of this modification, when the predicted demand falls below the target demand, the system target value is increased (by changing from the set target value to the changed target value), thereby increasing the power demand and controlling the power demand at the end of the demand time limit to approach the target demand.

[0061] In the power system of this modification, the demand discrepancy determination unit 133 of the target setting unit 13 of the processing device A1 determines whether the predicted demand is a demand surplus prediction that falls below the target demand. If the predicted demand is a demand surplus prediction, the target change unit 134 changes the system target value in a direction that eliminates the demand surplus, and the command value calculation unit 14 calculates an induced command value using the changed target value, which is the system target value changed by the target change unit 134, at the time of the demand surplus prediction. With this configuration, if the power demand in the current demand time period is predicted to be a demand surplus that falls below the target demand, the system target value is changed in a direction that eliminates the demand surplus. This allows the power system of this modification to suppress the demand surplus. Therefore, the power system of this modification can suppress the demand surplus while preventing the power demand at the end of the current demand time period from exceeding the target demand.

[0062] In a configuration different from the above-described modified example, the demand discrepancy determination unit 133 may determine whether or not the demand discrepancy prediction is a demand surplus prediction without performing a demand excess prediction as the demand discrepancy prediction. That is, the demand discrepancy determination unit 133 may determine that the demand discrepancy prediction is a demand surplus prediction (demand discrepancy prediction) when the predicted demand is smaller than the target demand, and may determine that the demand discrepancy prediction is not a demand surplus prediction (not a demand discrepancy prediction) when the predicted demand is equal to or larger than the target demand.

[0063] The power system according to the present disclosure is not limited to the above-described embodiment, and the specific configuration of each part of the power system according to the present disclosure can be freely modified in various ways. [Explanation of symbols]

[0064] S1: power system, A1: processing device, B1: power control device, D: power system, X: power equipment, 13: target setting unit, 14: command value calculation unit, 131: storage unit, 132: demand prediction unit, 133: demand difference determination unit, 134: target change unit

Claims

1. A power system that controls a value of a connection point power at a connection point with a power grid to a system target value, a processing device including a target setting unit that sets the system target value, and a command value calculation unit that calculates an induction command value for setting the value of the connection point power to the system target value; a plurality of power control devices each connected to a corresponding power device, the power control devices controlling output power of the corresponding power device based on the common induction command value calculated by the processing device; Equipped with The goal setting unit a storage unit in which a set target value that is a system target value is stored in advance; a demand prediction unit that estimates a predicted demand, which is a predicted value of the power demand at the end of a current demand time period; a demand difference determination unit that determines whether or not the demand difference prediction is a demand difference between the predicted demand and a target demand; a target change unit that changes the system target value in a direction that reduces the demand difference when the demand difference prediction is made; The command value calculation unit calculates the induced command value using a changed target value that is a system target value changed by the target change unit during the demand difference prediction.

2. 2. The power system according to claim 1, wherein the demand prediction unit estimates the predicted demand using an amount of power already received from the power grid in a current demand time period and a current value of the connection point power.

3. 3 . The power system according to claim 1 , wherein the target change unit takes into account a remaining time in a current demand time limit when changing the system target value from the set target value to the changed target value. 4 .

4. The power system according to claim 3 , wherein the target change unit calculates the change target value by calculation of the following equation (1): Change target value = Set target value - (Predicted demand - Target demand) x Set time of demand period x Coefficient / Remaining time (1)

5. the demand discrepancy determination unit determines that the demand discrepancy prediction is a demand excess prediction when the demand difference occurs due to a demand excess where the predicted demand exceeds the target demand, and The power system according to claim 1 , wherein the target change unit changes the system target value in a direction that resolves the demand excess when the demand excess is predicted.

6. the demand discrepancy determination unit determines that the demand discrepancy prediction is a demand surplus prediction when the demand difference is caused by a demand surplus in which the predicted demand is lower than the target demand, and The power system according to claim 1 or 5, wherein the target change unit changes the system target value in a direction that eliminates the demand surplus when the demand surplus is predicted.

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