JP6783288B2 - Power control device and power control method - Google Patents

Description

The present invention relates to a power control device and a power control method.

In recent years, the number of power generation facilities that operate interconnected with commercial power systems is increasing. In this power generation facility, in addition to being able to purchase power from the commercial power system, it is also possible to reverse power flow to the commercial power system and sell it to a power supply company. However, when connecting a power generation facility that generates renewable energy such as solar power generation to a commercial power system, the power can flow backward to the commercial power system depending on the peak output of the generated power and the capacity of the power transmission equipment and substation equipment of the commercial power system. The amount of power is limited. In addition, when the power flowing back from the power generation facility to the commercial power system becomes excessive with respect to the power demand, the power generation facility may be automatically disconnected from the commercial power system. Alternatively, the power supply company may request the discontinuation of the power generation equipment. Therefore, the power generation of the power generation facility that can be connected to the commercial power system includes power that allows reverse power flow to be transmitted / transformed in the commercial power system even at the peak of the generated power, and the commercial power system. It is limited to be less than the power demand in.

As an example of the prior art related to the present invention, Patent Document 1 teaches a power generation system including a solar cell and a power storage device. In this power generation system, when the system voltage value at the time of reverse power flow to the commercial power system exceeds the threshold voltage, the reverse power flow is stopped and the generated power is charged to the power storage device.

Japanese Unexamined Patent Publication No. 2013-172495

However, the output of generated power derived from natural energy is unstable depending on the weather and the like. In addition, the peak time of the output of the generated power is also relatively short. Therefore, during most of the non-peak hours, the capacity of the transmission equipment and the substation equipment is excessive with respect to the power flowing back to the commercial power system, and the operating rate of the transmission equipment and the substation equipment does not increase so much. Patent Document 1 does not mention such a problem at all.

In view of the above situation, an object of the present invention is to provide a power control device and a power control method capable of increasing the operating rate of power transmission equipment and substation equipment of a commercial power system.

In order to achieve the above object, the power control device according to one aspect of the present invention converts at least one of the generated power of the power generation device and the discharge power of the power storage device into power and outputs the power to an energized path connected to the commercial power system. Based on the detection result of the power conversion unit and the power detector that detects the backflow power flowing back from the current-carrying path to the commercial power system, it is determined whether or not the power value of the backflow power reaches the upper limit set value. A power determination unit and a charge / discharge control unit that controls charging / discharging of the power storage device are provided, and when it is determined that the power value of the reverse power flow power reaches the upper limit set value, the charge / discharge control unit is at least one of the generated powers. The unit is configured to charge the power storage device.

In the above power control device, when it is determined that the power value of the reverse power flow power reaches the upper limit set value, the charge / discharge control unit determines that the power value of the reverse power flow power does not exceed the upper limit set value. At least a part of the power storage device may be charged.

In the above power control device, if it is not determined that the power value of the reverse power flow power reaches the upper limit set value, the charge / discharge control unit may be configured to discharge the power storage device.

In the above power control device, the power determination unit further determines whether or not reverse power flow is reverse power flow from the current-carrying path to the commercial power system based on the detection result of the power detector, and the reverse power flow power is reverse power flow. If it is determined that the power supply is reverse power and the power value of the reverse power flow power does not reach the upper limit set value, the charge / discharge control unit stops charging / discharging of the power storage device, and it is not determined that the reverse power flow power is reverse power flow. In this case, the charge / discharge control unit may be configured to discharge the power storage device.

In the above power control device, the power determination unit determines whether or not the reverse power flow is flowing backward from the energization path to the commercial power system, and the power of the reverse power flow power when the charge / discharge control unit discharges the power storage device. The power detector determines whether the value is less than or equal to the discharge power and whether the power value of the reverse power flow power reaches the set power value less than the upper limit set value when the charge / discharge control unit discharges the power storage device. When it is determined that the reverse power flow is backflowed to the commercial power system and the backflow power is less than or equal to the discharge power when the charge / discharge control unit is discharging the power storage device. The charge / discharge control unit may be configured to discharge the power storage device so that the power value of the reverse power flow power does not exceed the set power value.

In the above power control device, there may be a plurality of upper limit set values, and each upper limit set value may be set for each predetermined period.

Further, in order to achieve the above object, in the power control method according to one aspect of the present invention, at least one of the generated power of the power generation device and the discharge power of the power storage device is converted into power and connected to a commercial power system. The upper limit of the power value of the reverse power flow power is based on the detection result of the step output to, the step of detecting the power value of the reverse power flow power flowing back from the current-carrying path to the commercial power system, and the detected step. A step of determining whether or not to reach the set value and a step of controlling the charge / discharge of the power storage device are provided, and in the step in which the charge / discharge is controlled, the power value of the reverse power flow reaches the upper limit set value. When it is determined that the power is generated, at least a part of the generated power is charged to the power storage device.

Further, in order to achieve the above object, the power control system according to one aspect of the present invention converts at least one of the generated power of the power generation device and the discharge power of the power storage device into an energized path connected to the commercial power system. It is equipped with a power control device that outputs power and a power detector that detects reverse power flow from the current-carrying path to the commercial power system. When the power value of reverse power flow reaches the upper limit set value, the power control device The power storage device is configured to charge at least a part of the generated power.

According to the present invention, it is possible to increase the operating rate of power transmission equipment and substation equipment of a commercial power system.

It is a block diagram which shows the 1st configuration example of a photovoltaic power generation system. It is a block diagram which shows the connection example of a plurality of solar cell strings and a DC / DC converter. It is a block diagram which shows the other connection example of a plurality of solar cell strings and a DC / DC converter. It is a flowchart for demonstrating the power control process in 1st Embodiment. It is a graph which shows an example of the electric power utilization situation of one day in 1st Embodiment. It is a block diagram which shows the modification of the 1st configuration example of a photovoltaic power generation system. It is a block diagram which shows the configuration example of a wind power generation system. It is a block diagram which shows the other configuration example of a wind power generation system. It is a flowchart for demonstrating the power control process in 2nd Embodiment. It is a graph which shows an example of the electric power utilization situation of one day in 2nd Embodiment. It is a flowchart for demonstrating the power control process in 3rd Embodiment. It is a graph which shows an example of the electric power utilization situation of one day in 3rd Embodiment. It is a flowchart for demonstrating the power control processing in 4th Embodiment. It is a graph which shows an example of the electric power utilization situation of one day in 4th Embodiment. It is a block diagram which shows the 2nd configuration example of a photovoltaic power generation system. It is a block diagram which shows the modification of the 2nd configuration example of a photovoltaic power generation system. It is a flowchart for demonstrating the electric power control processing in 5th Embodiment. It is a flowchart for demonstrating the power control processing in 6th Embodiment. It is a flowchart for demonstrating the power control process in 7th Embodiment.

An embodiment of the present invention will be described below with reference to the drawings.

<First Embodiment>
FIG. 1 is a block diagram showing a first configuration example of the photovoltaic power generation system 100. The photovoltaic power generation system 100 is a power control system that is electrically connected to the commercial power system CS and the power load system LS via, for example, a single-phase three-wire energization path P. In the photovoltaic power generation system 100, grid interconnection operation by the solar cell string 1 and the power storage device 2 and the commercial power system CS is possible. Further, in the photovoltaic power generation system 100, the generated electric power may be converted from direct current to alternating current, reverse power flow (output) to the commercial electric power system CS via the energization path P, and the electric power may be sold to the electric power company. It is possible. In the following, the power that is reverse-powered to the commercial power system CS via the current-carrying path P and sold is referred to as reverse-feed power, and the reverse power and its power value are represented by WC. Further, the power purchased from the commercial power system CS and output to the energization path P is called the received power.

The current-carrying path P includes a first current-carrying path Pa and a second current-carrying path Pb. The first current path Pa is connected to the power conditioner 3 of the photovoltaic power generation system 100. In the following, the power conditioner 3 will be referred to as a PCS (Power Conditioning System) 3.

The second current-carrying path Pb is connected to the commercial power system CS. A watt hour meter M is provided on the second energization path Pb. The watt hour meter M is a power detector that detects the direction in which power flows in the second current-carrying path Pb, the amount of power, and the power value, and outputs a detection signal indicating the detection result to PCS3. For example, in the watt hour meter M, when power flows from the solar power generation system 100 toward the commercial power system CS in the second energization path Pb, the solar power generation system 100 sells power to the commercial power system CS. Detects the amount and value of reverse power flow. Further, in the watt hour meter M, when power flows from the commercial power system CS to the solar power generation system 100 and / or the power load system LS in the second energization path Pb, the solar power generation system 100 is transmitted from the commercial power system CS. Detects that power is being purchased and the amount and value of received power.

Further, a power load system LS is connected between the first current-carrying path Pa and the second current-carrying path Pb. This electric power load system LS is, for example, a load device such as an electric appliance in a home or an equipment of a factory, and consumes electric power supplied from the first electric circuit Pa and / or the second electric circuit Pb. In the following, the power supplied to and consumed by the power load system LS is referred to as power consumption, and the power consumption and its power value are represented by WL.

Next, the solar cell string 1 is a power generation device including a plurality of solar cell modules connected in series, receives sunlight to generate power, and outputs the generated DC power to the PCS3. In the following, the electric power output from the solar cell string 1 to the PCS3 is referred to as generated electric power, and the generated electric power and its electric power value are represented by Wg. The number of solar cell strings 1 provided in the photovoltaic power generation system 100 is not limited to the example shown in FIG. 1, and may be plural. For example, a plurality of solar cell strings 1 connected in parallel to each other may be connected to PCS3 (DC / DC converter 31 described later). In this case, each solar cell string 1 may be connected to the PCS 3 via a backflow prevention device that prevents a backflow current from flowing through the solar cell string 1. Further, the solar cell string 1 may be configured to include one solar cell module.

The power storage device 2 has a charge / discharge function capable of repeatedly charging / discharging. For example, the power storage device 2 can charge the DC power supplied from the PCS 3, and can also discharge the DC power corresponding to the stored amount wa to the PCS 3. Hereinafter, the electric power supplied from the PCS 3 to the power storage device 2 at the time of charging is referred to as charge power, and the power output from the power storage device 2 to the PCS 3 at the time of discharge is referred to as discharge power. Further, the discharge power and its power value are represented by Wd. The configuration of the power storage device 2 is not particularly limited. For example, the power storage device 2 may include a secondary battery such as a lithium secondary battery, a nickel hydrogen battery, a nickel cadmium battery, and a lead battery. Alternatively, the power storage device 2 may include an electric double layer capacitor or the like. Further, the number of the power storage devices 2 is not limited to the example of FIG. 1, and may be a plurality.

The power storage device 2 has an input / output power detection unit 21. The input / output power detection unit 21 detects the charge / discharge operation (charging, discharging, charging / discharging stop) of the power storage device 2 and its state. For example, the input / output power detection unit 21 detects the charging operation of the power storage device 2, the power value of the charging power, the power value of the discharging operation and the discharging power Wd, the stop of the charging / discharging operation, and the like. These detection results are output from the power storage device 2 to the PCS 3 by the status notification signal. The charging / discharging operation of the power storage device 2 and the method of detecting the state thereof are not particularly limited. For example, the input / output power detection unit 21 may detect from a change in the current input / output to / from the power storage device 2. In this case, the input / output power detection unit 21 detects the charge / discharge operation of the power storage device 2 based on the direction in which the current flows between the third energization path Pc and the power storage device 2. Then, the input / output power detection unit 21 can detect the power value of the charging power or the discharging power Wd by using the change in the value of the current and the nominal voltage of the power storage device 2.

The PCS 3 is a power control device provided between the solar cell string 1 and the power storage device 2 and the commercial power system CS. Normally, the PCS3 controls the operating voltage (operating point) of the solar cell string 1 so that the generated power Wg is maximized by, for example, MPPT (Maximum Power Point Tracking) control. However, when it is necessary to limit the amount of power generated by the solar cell string 1, the PCS 3 sets the operating voltage of the solar cell string 1 to a value deviated from the maximum output operating voltage and adjusts the generated power Wg. In addition, the PCS 3 can also control the charge / discharge function of the power storage device 2. For example, the PCS 3 supplies charging power to the power storage device 2 to charge the power storage device 2, or discharges the power storage device 2 to receive the discharge power Wd.

The PCS 3 includes a DC / DC converter 31, a bidirectional inverter 32, a bidirectional DC / DC converter 33, a smoothing capacitor 34, a communication unit 35, a storage unit 36, and a control unit 37. The DC / DC converter 31, the bidirectional inverter 32, and the bidirectional DC / DC converter 33 are connected to each other via the bus line BL.

The DC / DC converter 31 is provided between the solar cell string 1 and the bus line BL, converts the generated power Wg of the solar cell string 1 into DC power having a predetermined voltage value, and outputs the DC / DC converter 31 to the bus line BL. The DC / DC converter 31 also functions as a backflow prevention device that prevents a backflow current from flowing through the solar cell string 1. When a plurality of solar cell strings 1 are connected to the PCS 3, each solar cell string 1 is connected to the DC / DC of the PCS 3 via a junction box 12 including a plurality of backflow prevention devices 11 connected in parallel as shown in FIG. 2A. It may be connected to the DC converter 31. Alternatively, as shown in FIG. 2B, the PCS 3 may include a plurality of DC / DC converters 31 connected in parallel to each other, and each solar cell string 1 may be connected to each DC / DC converter 31.

The bidirectional inverter 32 is a power conversion unit controlled by the control unit 37, and is provided between the bus line BL and the first energization path Pa. The bidirectional inverter 32 can perform bidirectional power conversion as shown in FIG. 1 by PWM (Pulse Width Modulation) control, PAM (Pulse Amplitude Modulation) control, or the like. For example, the bidirectional inverter 32 can AC / DC convert AC power input from the first current path Pa into DC power and output it to the bus line BL. Further, the bidirectional inverter 32 makes the DC power (at least one of the generated power Wg and the discharge power Wd of the power storage device 2) input from the bus line BL according to the power standards of the commercial power system CS and the power load system LS. It can be DC / AC converted into AC power of the AC frequency and output to the first current path Pa. In the following, the bidirectional inverter 32 power-converting the power input from the first current-carrying path Pa and outputting it to the bus line BL is referred to as power conversion in the forward conversion direction a. Further, the power conversion in the forward conversion direction a is called a forward conversion, and the power conversion amount of the power to be forward-converted is called a forward conversion amount. Further, the bidirectional inverter 32 converts the power input from the bus line BL into power and outputs it to the first current path Pa, which is called power conversion in the reverse conversion direction b. Further, the power conversion in the inverse conversion direction b is called an inverse conversion, and the power conversion amount of the power to be inversely converted is called an inverse conversion amount.

The bidirectional DC / DC converter 33 is a charge / discharge power conversion unit controlled by the control unit 37, and is provided between the bus line BL and the power storage device 2. The bidirectional DC / DC converter 33 can DC / DC convert the DC power input from the bus line BL into DC charging power suitable for the power storage device 2 and output it to the power storage device 2. Further, the bidirectional DC / DC converter 33 can also DC / DC convert the discharge power Wd of the power storage device 2 into power according to the specifications of the bidirectional inverter 32 and output it to the bus line BL. In the following, the bidirectional DC / DC converter 33 converting the power input from the bus line BL into power and outputting it to the power storage device 2 is referred to as power conversion in the charging direction A. Further, the power conversion of the charging direction A is called a charge conversion, and the power conversion amount of the power to be charged is called a charge conversion amount. Further, the bidirectional DC / DC converter 33 converting the discharge power Wd of the power storage device 2 into power and outputting it to the bus line BL is called power conversion in the discharge direction B. Further, the power conversion in the discharge direction B is called a discharge conversion, and the power conversion amount of the power to be discharged is called a discharge conversion amount.

The smoothing capacitor 34 is connected to the bus line BL and removes or reduces fluctuations in the bus voltage value of the electric power flowing through the bus line BL.

The communication unit 35 is a communication interface for wireless communication or wired communication with the controller 4.

The storage unit 36 is a storage medium that non-temporarily holds the stored information without supplying electric power. The storage unit 36 stores control information, programs, and the like used in each component of the PCS 3 (particularly, the control unit 37). For example, the storage unit 36 stores the setting information of the upper limit setting value WS, which will be described later. This upper limit set value WS is a set value indicating the upper limit of the reverse power flow power WC that can reverse power flow from the photovoltaic power generation system 100 to the commercial power system CS. The upper limit set value WS is set to a value specified by the power supply company, for example, when constructing the photovoltaic power generation system 100 or during the operating period of the photovoltaic power generation system 10. Further, the upper limit setting value WS may be appropriately set at an arbitrary timing according to the user input.

The control unit 37 controls each component of the PCS 3 by using the control information, the program, and the like stored in the storage unit 36. The control unit 37 has a power monitoring unit 371, a power storage monitoring unit 372, a conversion control unit 373, a timer 374, and a power determination unit 375 as functional elements.

The power monitoring unit 371 monitors the power (reverse power flow power WC, received power) flowing through the second current-carrying path Pb. For example, the power monitoring unit 371 detects the direction in which power flows in the second energization path Pb, the amount of power, the power value, and the like based on the detection signal output from the watt hour meter M.

The power storage monitoring unit 372 monitors the state of the power storage device 2. For example, the power storage monitoring unit 372 detects the state of the power storage device 2 based on the status notification signal output from the power storage device 2. The state of the power storage device 2 includes the storage capacity wr, the storage amount wa, and the state of charge / discharge operation (for example, the power value of charge operation and charge power, the power value of discharge operation and discharge power Wd, and the stop of charge / discharge operation. ) Etc. are included.

The conversion control unit 373 controls the bidirectional inverter 32 and the bidirectional DC / DC converter 33, and particularly controls the power conversion direction and the power conversion operation of these. The conversion control unit 373 also functions as a charge / discharge control unit that controls the charge / discharge function of the power storage device 2. For example, the conversion control unit 373 can be used on both sides based on the state of the solar power generation system 100 (power sale, power purchase, self-consumption of power, and these power values, etc.), the state of the power storage device 2, and user input. It detects the power conversion operation of the inverter 32 and the bidirectional DC / DC converter 33, and controls the power conversion operation. The control of the power conversion operation includes switching of the power conversion direction, adjustment of the power conversion amount, stopping of the power conversion, and the like. The conversion control unit 373 controls the charge / discharge function of the power storage device 2 by controlling these power conversion operations.

The timer 374 is a time measuring unit, and measures the current time or the elapsed time from a predetermined time point to the present time.

The power determination unit 375 makes various determinations based on the detection result of the watt-hour meter M and the state of the power storage device 2. For example, the power determination unit 375 determines whether or not the reverse power flow power WC reaches a predetermined threshold value (upper limit set value WS, etc.) based on the detection result of the watt hour meter M, or determines from the PCS3 the commercial power system CS. It is determined whether or not the reverse power flow WC is reverse power flow.

Next, the controller 4 will be described. The controller 4 includes a display unit 41, an input unit 42, a communication unit 43, and a control unit 44. The display unit 41 displays information about the photovoltaic power generation system 100 on a display (not shown). The input unit 42 receives the user input and outputs an input signal corresponding to the user input to the control unit 44. The communication unit 43 is a communication interface for wireless communication or wired communication with the PCS3. The communication unit 43 transmits, for example, information regarding user input received by the input unit 42 to the PCS3. The control unit 44 controls each component of the controller 4 by using control information, a program, or the like stored in a memory (not shown) that holds the information non-temporarily.

Next, the power control method of the photovoltaic power generation system 100 will be described. FIG. 3 is a flowchart for explaining the power control process according to the first embodiment. In FIG. 3, in the case of selling power, the bidirectional inverter 32 is set in the reverse conversion direction b. This also applies to other figures described later (for example, FIGS. 7, 9, and 11).

First, it is determined whether or not the reverse power flow power WC is reverse power flowed from the photovoltaic power generation system 100 to the commercial power system CS and sold (S101). If it is not determined that the power is sold (NO in S101), the process proceeds to S140 described later. When it is determined that the power is sold (YES in S101), it is determined whether or not the bidirectional DC / DC converter 33 is set in the charging direction A (S110). If it is not determined that the charging direction A is set (NO in S110), the process proceeds to S120, which will be described later.

When it is determined that the charging direction A is set (YES in S110), it is determined whether or not the reverse power flow power WC reaches the upper limit set value WS (S111). When it is determined that the reverse power flow power WC reaches the upper limit set value WS (YES in S111), the charge conversion amount of the bidirectional DC / DC converter 33 is increased in order to reduce the reverse power flow power WC (S112). Therefore, of the generated power Wg, the charging power supplied to the power storage device 2 is large, and the power output to the first current-carrying path Pa is small. Then, the process returns to S101.

When it is not determined that the reverse power flow power WC reaches the upper limit set value WS (NO in S111), it is determined whether or not the charge conversion amount of the bidirectional DC / DC converter 33 is 0 (S113). When it is determined that the charge conversion amount is 0 (YES in S113), the bidirectional DC / DC converter 33 is set in the discharge direction B (S114). Therefore, the power storage device 2 starts the discharge operation and outputs the discharge power Wd. This discharge power Wd is output to the bus line BL, reversely converted by the bidirectional inverter 32 together with the generated power Wg, and output to the first current path Pa. Then, the process returns to S101.

If it is not determined that the charge conversion amount is 0 (NO in S113), the charge conversion amount of the bidirectional DC / DC converter 33 is reduced in order to increase the reverse power flow power WC (S115). Therefore, of the generated power Wg, the charging power supplied to the power storage device 2 is small, and the power output to the first current-carrying path Pa is large. Then, the process returns to S101.

Next, when S110 is NO (when it is not determined that the charging direction A is set at the time of selling power), it is determined whether or not the bidirectional DC / DC converter 33 is set in the discharging direction B. (S120). If it is not determined that the discharge direction B is set (NO in S120), the process proceeds to S130 described later.

When it is determined that the discharge direction B is set (YES in S120), it is determined whether or not the electricity storage amount wa of the electricity storage device 2 is equal to or less than the lower limit value wy (S122). When it is determined that wa ≦ wy (YES in S122), the power conversion operation of the bidirectional DC / DC converter 33 is stopped (S123). Therefore, the power storage device 2 does not perform a charging operation or a discharging operation. Then, the process returns to S101. The lower limit value wy is a value indicating that the storage amount wa of the power storage device 2 is small (for example, a state close to 0 [W]). The lower limit value wy is set within the range of 0 or more and less than the storage capacity wr (0 ≦ wy <wr), but it is more preferably set by 0 <wy <wr. If the discharge operation is performed in a state where the amount of electricity stored in the power storage device 2 is small (for example, a state close to 0 [W]), the charge / discharge function of the power storage device 2 tends to deteriorate. Therefore, if the power storage device 2 is prevented from discharging in such a case, deterioration of the charge / discharge function can be suppressed or prevented.

If it is not determined that wa ≦ wy (NO in S122), it is determined whether or not the reverse power flow power WC reaches the upper limit set value WS (S124). When it is determined that the reverse power flow power WC reaches the upper limit set value WS (YES in S124), the discharge conversion amount of the bidirectional DC / DC converter 33 is reduced in order to reduce the reverse power flow power WC (S125). Therefore, the discharge power Wd output from the power storage device 2 to the first energization path Pa is reduced. Then, the process returns to S101.

If it is not determined that the reverse power flow power WC reaches the upper limit set value WS (NO in S124), the discharge conversion amount of the bidirectional DC / DC converter 33 is increased in order to increase the reverse power flow power WC (S126). Therefore, the discharge power Wd output from the power storage device 2 to the first energization path Pa increases. Then, the process returns to S101.

Next, when S120 is NO (when it is not determined that the discharge direction B is set at the time of selling power), the bidirectional DC / DC converter 33 has stopped the power conversion operation. In this case, it is determined whether or not the reverse power flow power WC reaches the upper limit set value WS (S130). If it is not determined that the reverse power flow power WC reaches the upper limit set value WS (NO in S130), the process proceeds to S140 described later. When it is determined that the reverse power flow WC reaches the upper limit set value WS (YES in S130), the bidirectional DC / DC converter 33 is set in the charging direction A (S131). Therefore, the power storage device 2 starts the charging operation to charge the charging power supplied from the bidirectional DC / DC converter 33. That is, charging of the generated power Wg is started. Then, the process returns to S101.

Next, in the case of NO in S101 (when it is not determined that the power is sold) and in the case of NO in S130 (when it is not determined that the reverse power flow power WC reaches the upper limit set value WS), the power storage of the power storage device 2 It is determined whether or not the amount wa is equal to or less than the lower limit value wy (S140). When it is determined that wa ≦ wy (YES in S140), the power conversion operation of the bidirectional DC / DC converter 33 is stopped (S141). Therefore, the power storage device 2 does not perform the charging operation or the discharging operation, and the process returns to S101.

If it is not determined that wa ≦ wy (NO in S140), the bidirectional DC / DC converter 33 is set in the discharge direction B (S144). Therefore, the discharge power Wd is output from the power storage device 2 and is output to the first current-carrying path Pa together with the generated power Wg. Then, the process returns to S101.

Next, an example of power control of the photovoltaic power generation system 100 based on the above-mentioned power control process will be described. FIG. 4 is a graph showing an example of the daily power usage status in the first embodiment. In FIG. 4, the sunrise is around 6:00 and the sunset is around 18:00. Further, in FIG. 4, in order to make it easier to understand the contents of the power control, a case where the power consumption WL in the power load system LS is constant is illustrated. Further, in the time zone from 0:00 to 11:00, the electricity storage amount wa of the electricity storage device 2 is below the lower limit value wy due to the discharge on the previous day, so that the electricity storage device 2 is not discharged. These are the same in the drawings (for example, FIGS. 8, 10, and 12) for explaining other power control examples described later.

First, solar power generation is not possible during the time zones of 0:00 to 6:00 and 18:00 to 24:00. Therefore, the photovoltaic power generation system 100 purchases the received power corresponding to the power consumption WL of the power load system LS from the commercial power system CS and consumes it in-house.

Photovoltaic power generation is possible from 6:00 to 18:00. However, in the time zones of 6:00 to 8:00 and 17:00 to 18:00, since the intensity of sunlight is relatively low, the generated power Wg exceeding the power consumption WL is not obtained. Therefore, the generated power Wg is consumed in-house by the power load system LS, and the received power having a power value (WL-Wg) corresponding to the shortage is purchased from the commercial power system CS. In the time zone from 8:00 to 9:00 and 16:00 to 17:00, the generated power Wg having almost the same power value as the power consumption WL is obtained, but the generated power Wg is almost self-consumed in the power load system LS. Will be done. Therefore, the photovoltaic power generation system 100 does not buy or sell power.

In the time zone from 9:00 to 16:00, the generated power Wg exceeding the power consumption WL is obtained. Therefore, a part of the generated power Wg (power having the same power value as the power consumption WL) is consumed in-house by the power load system LS, and the remaining part (Wg-WL) is reverse to the commercial power system CS as reverse power flow power WC. Tide (power sale). However, in the time zone from 11:00 to 14:00, the reverse power flow power WC reaches the upper limit set value WS. Therefore, of the remaining partial power (Wg-WL), the reverse power flow power WC having the same power value as the upper limit set value WS is sold to the commercial power system CS. Further, the power storage device 2 is charged with the power of the power value {Wg− (WS + WL)} obtained by subtracting the sum of the upper limit set value WS and the power consumption WL of the power load system LS from the power value of the generated power Wg.

Next, in the time zone from 14:00 to 16:00, the power value of the remaining part (Wg-WL) described above is less than the upper limit set value WS. Therefore, the discharge power Wd to which the reverse power flow power WC does not exceed the upper limit set value WS is output from the power storage device 2 to the first current-carrying path Pa via the PCS3. That is, the discharge power Wd of the power value {WS- (Wg-WL)} corresponding to the difference between the upper limit set value WS and the remaining part (Wg-WL) of the generated power Wg is output. Then, of the power obtained by adding the discharge power Wd to the generated power Wg, the power corresponding to the power consumption WL is consumed in-house by the power load system LS, and the remaining power is sold to the commercial power system CS as reverse power flow power WC. Will be done.

The reverse power flow power WC has the same power value as the upper limit set value WS in the time zone 14:00 to 15:00 in FIG. 4, but the reverse power flow power WC has an upper limit in the time zone 15:00 to 16:00. It is less than the set value WS. Further, in the time zone from 16:00 to 24:00, the discharge power Wd is not output to the first energization path Pa. These reasons are that the amount of electricity stored in the power storage device 2 becomes equal to or less than the lower limit value Wy around 16:00, and the discharge power Wd is no longer output from the power storage device 2.

As described above, according to the present embodiment, the power control device 3 converts at least one of the generated power Wg of the power generation device 1 and the discharge power Wd of the power storage device 2 into a power path P connected to the commercial power system CS. The power value of the reverse power flow power WC is the upper limit set value based on the detection results of the power conversion unit 32 that outputs the power and the power detector M that detects the reverse power flow power WC that is reverse power flowed from the energization path P to the commercial power system CS. It includes a power determination unit 375 that determines whether or not the power reaches WS, and a charge / discharge control unit 373 that controls charging / discharging of the power storage device 2. When it is determined that the power value of the reverse power flow power WC reaches the upper limit set value WS, the charge / discharge control unit 373 charges the power storage device 2 with at least a part of the generated power Wg.

Further, the power control method includes a step in which at least one of the generated power Wg of the power generation device 1 and the discharge power Wd of the power storage device 2 is converted into power and output to the energization path P connected to the commercial power system CS. The power value of the reverse power flow power WC is set as the upper limit setting value WS based on the step in which the power value of the reverse power flow power WC flowing backward from the current path P to the commercial power system CS and the detection result in the detected step are detected. It includes a step of determining whether or not to reach the above, and a step of controlling the charging / discharging of the power storage device 2. The step in which charging / discharging is controlled includes a step in which at least a part of the generated power Wg is charged to the power storage device 2 when it is determined that the power value of the reverse power flow power WC reaches the upper limit set value WS.

Further, the power control system 100 has a power control device 3 that converts at least one of the generated power Wg of the power generation device 1 and the discharge power Wd of the power storage device 2 into power and outputs the power to the energization path P connected to the commercial power system CS. A power detector M that detects a reverse power flow WC that is reversely flowed from the current path P to the commercial power system CS is provided. When the power value of the reverse power flow power WC reaches the upper limit set value WS, the power control device 3 charges the power storage device 2 with at least a part of the generated power Wg.

According to these configurations, when the power value of the reverse power flow power WC increases during the peak output period of the generated power Wg and the power value of the reverse power flow power WC reaches the upper limit set value WS, at least one of the generated power Wg The unit is charged to the power storage device 2. Therefore, it is possible to prevent the power value of the reverse power flow power WC from exceeding the upper limit set value WS without wasting the generated power Wg. For example, consider a case where power is generated using a power generation device 1 having a large power generation capacity such that the generated power Wg during the peak output period exceeds the upper limit set value WS. Even in this case, the reverse power flow power WC during the peak output period can be prevented from exceeding the upper limit set value by charging the power storage device 2 with the electric power exceeding the upper limit set value WS. Therefore, since the power generation device 1 having a relatively large power generation capacity can be provided in the power control system 100, the reverse power flow power WC having a power value closer to the upper limit set value WS can be commercialized even during a period other than the peak output period. It can reverse power flow to the power system CS. Therefore, the operating rate of the power transmission equipment and the substation equipment of the commercial power system CS can be increased. In particular, the operating rate can be increased during periods other than the peak output period. Further, since the operating rates of the power transmission equipment and the substation equipment during the peak output period of the generated power Wg can be prevented from exceeding the permissible threshold value, the number of power generation equipment that can be connected to the commercial power system CS can be increased.

Further, it is possible to prevent the reverse power flow power WC from becoming excessive with respect to the power demand of the commercial power system CS during the peak output period of the generated power Wg. Therefore, it is possible to suppress or prevent the power control system 100 from being disconnected from the commercial power system CS, and the power control system 100 can stably perform grid interconnection operation with the commercial power system CS.

Further, according to the present embodiment, when it is determined that the power value of the reverse power flow power WC reaches the upper limit set value WS, the charge / discharge control unit 373 causes the power value of the reverse power flow power WC to exceed the upper limit set value WS. The power storage device 2 is charged with at least a part of the generated power Wg so as not to be present.

According to this configuration, the power value of the reverse power flow power WC can be brought close to the same value as the upper limit set value WS or the upper limit set value WS. Therefore, the reverse power flow power WC can be efficiently sold to the commercial power system CS.

Further, according to the present embodiment, when the power control device 3 does not determine that the power value of the reverse power flow power WC reaches the upper limit set value WS, the charge / discharge control unit 373 discharges the power storage device 2.

According to this configuration, the charging power charged in the power storage device 2 during the peak output period of the generated power Wg is discharged in a period other than the peak output and output to the energization path P. Therefore, the generated power Wg can be peak-shifted and used without waste.

In the above, the configuration of the photovoltaic power generation system 100 and its power control processing have been described based on the first configuration example of FIG. 1, but the configuration of the photovoltaic power generation system 100 is not limited to the example of FIG. FIG. 5 is a block diagram showing a modified example of the first configuration example of the photovoltaic power generation system 100. In FIG. 5, the solar cell string 1 is connected to one end of the first current path Pa via the DC / AC converter 13. The DC / AC converter 13 DC / AC converts the generated power Wg of the solar cell string 1 into AC power having an AC frequency corresponding to the power standards of the commercial power system CS and the power load system LS, and converts it into the first current-carrying path Pa. Output. The DC / AC converter 13 also functions as a backflow prevention device that prevents a backflow current from flowing through the solar cell string 1. The DC / AC converter 13 may be controlled by the PCS3 or may be controlled by another PCS (not shown) different from the PCS3. The power storage device 2 is connected to the PCS 3. The PCS 3 controls the charge / discharge function of the power storage device 2.

Further, although the solar cell string 1 is used as the power generation device in FIGS. 1 and 5, the power generation device is not limited to these examples. A power generation device that generates power using renewable energy other than solar power (wind power, hydropower, geothermal power, biomass, natural energy power generation such as solar heat, waste power generation, etc.) may be used. For example, as shown in FIGS. 6A and 6B, the wind power generation system 100 may use the wind power generation device 1 as the power generation device. In the case of FIG. 6A, the PCS 3 has an AD / DC converter 38 to which the wind power generation device 1 is connected. In the case of FIG. 6B, the wind power generation device 1 is connected to the first current-carrying path Pa, and the PCS 3 controls the charge / discharge function of the power storage device 2. Further, in FIG. 6B, the wind power generation device 1 may be connected to the first current-carrying path Pa via an AC / AC converter (not shown) controlled by PCS3 or another PCS (not shown).

Even if the power generation device is connected to the first current-carrying path Pa and the generated power Wg is output to the first current-carrying path Pa as shown in FIGS. 5 and 6B, the same power control as in FIG. 4 is possible. Is. For example, in the above-mentioned power control process (see FIG. 3), in the process of switching and setting the power conversion direction of the bidirectional DC / DC converter 33 (S114, S123, S131, S141, S144, etc. in FIG. 3), The power conversion direction of the bidirectional inverter 32 may also be switched and set. This also applies to other power control processes and other power controls as shown in FIGS. 7 to 12 described later.

Further, in FIGS. 5 and 6B, the PCS 3 has a bidirectional DC / AC converter (not shown) controlled by the conversion control unit 373 instead of the bidirectional inverter 32 and the bidirectional DC / DC converter 33. You may. Even with such a configuration, if the power conversion operation of the bidirectional DC / AC converter (not shown) is controlled in the same manner as the bidirectional DC / DC converter 33, the same power control as in FIG. 4 is possible. This also applies to other power control processes and other power controls as shown in FIGS. 7 to 12 described later.

<Second Embodiment>
Next, the second embodiment will be described. In the second embodiment, a plurality of upper limit setting values WS1 to WS7 are set for each time zone of the day. Other than this, it is the same as that of the first embodiment. Hereinafter, a configuration different from that of the first embodiment will be described. Further, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof may be omitted.

In the photovoltaic power generation system 100 of the second embodiment, the upper limit set value WS includes a plurality of upper limit set values WS1 to WS7 set for each time zone of the day (see FIG. 8 described later). The setting method of each upper limit setting value WS1 to WS7 is not limited to this example. For example, each upper limit setting value WS1 to WS7 may be set not only in a time zone of one day but also in a predetermined period (for example, every day of the week, every week, every month, etc.).

FIG. 7 is a flowchart for explaining the power control process in the second embodiment. If YES in S101 (when it is determined that power is sold from the photovoltaic power generation system 100 to the commercial power system CS), the current time is clocked (S202), and the upper limit corresponding to the time zone including the current time. The set value WS is determined (S203). In the subsequent processing, charge / discharge control of the power storage device 2 is performed by controlling the power conversion operation of the bidirectional DC / DC converter 33 based on the upper limit set value WS determined in S203. The processing after S110 is the same as that of the first embodiment (see FIG. 3). Therefore, these explanations are omitted.

Next, an example of power control of the photovoltaic power generation system 100 based on the above-mentioned power control process will be described. FIG. 8 is a graph showing an example of the daily power usage status in the second embodiment. In FIG. 8, the upper limit setting value WS1 is associated and set in the time zones 0:00 to 9:00 and 16:00 to 24:00. In the time zone from 9:00 to 10:00, the upper limit set value WS2 is associated and set. In the time zone from 10:00 to 11:00, the upper limit set value WS3 is associated and set. In the time zone from 11:00 to 12:00, the upper limit setting value WS4 is set in association with each other. In the time zone from 12:00 to 14:00, the upper limit setting value WS5 is associated and set. In the time zone from 14:00 to 15:00, the upper limit setting value WS6 is set in association with each other. In the time zone from 15:00 to 16:00, the upper limit setting value WS7 is associated and set.

In FIG. 8, in the time zone from 9:00 to 16:00, the generated power Wg exceeding the power consumption WL is obtained. Therefore, a part of the generated power Wg (power having the same power value as the power consumption WL) is consumed in-house by the power load system LS, and the remaining part (Wg-WL) is reverse to the commercial power system CS as reverse power flow power WC. Tide (power sale). However, in the time zone from 11:00 to 14:00, the reverse power flow power WC reaches the upper limit set values WS4 and WS5 corresponding to the current time. Therefore, in the time zone from 11:00 to 12:00, of the remaining part of the power (Wg-WL), the reverse power flow power WC having the same power value as the upper limit set value WS4 is sold to the commercial power system CS. The electric power of the electric power value {Wg− (WS4 + WL)} is charged to the power storage device 2. Further, in the time zone from 12:00 to 14:00, the reverse power flow power WC having the same power value as the upper limit set value WS5 is sold to the commercial power system CS, and the power of the power value {Wg- (WS5 + WL)} is stored in the power storage device. It is charged to 2.

Next, in the time zone from 14:00 to 16:00, the power value of the remaining part (Wg-WL) described above is less than the upper limit set values WS6 and WS7. Further, after the time of 16:00, the generated power Wg exceeding the power consumption WL has not been obtained. Therefore, the discharge power Wd to which the reverse power flow power WC does not exceed the upper limit set value WS is output from the power storage device 2 to the first current-carrying path Pa via the PCS3. Then, of the power obtained by adding the discharge power Wd to the generated power Wg, the power corresponding to the power consumption WL is consumed in-house, and the remaining power is sold to the commercial power system CS as the reverse power flow power WC.

In the time zone of FIG. 8 from 14:00 to 17:00, the reverse power flow power WC has the same power value as the upper limit set values WS6, WS7, and WS1, respectively, but in the time zone 17:00 to 18:00. The reverse power flow WC is less than the upper limit set value WS1. Further, in the time zone from 18:00 to 24:00, the discharge power Wd is not output from the power storage device 2. The reason for these is that the amount of electricity stored in the power storage device 2 becomes equal to or less than the lower limit value Wy around 18:00, and the discharge power Wd is no longer output.

As described above, according to the present embodiment, there are a plurality of upper limit set values WS, and each upper limit set value WS1 to WS7 is set for each predetermined period.

According to this configuration, the upper limit setting values WS1 to WS7 can be set for each predetermined period (for example, every predetermined time zone, every day of the week, every week, etc.). Therefore, more detailed power control can be performed according to the actual power generation amount of the power generation device 1 that fluctuates depending on the environmental conditions and the like, and the actual operating status of the commercial power system CS.

<Third Embodiment>
Next, the third embodiment will be described. In the third embodiment, the generated power Wg and the discharge power Wd of the power storage device 2 are supplied to the power load system LS and consumed in-house, but are not sold to the commercial power system CS. Other than this, it is the same as that of the first embodiment. Hereinafter, configurations different from those of the first and second embodiments will be described. Further, the same components as those in the first and second embodiments are designated by the same reference numerals, and the description thereof may be omitted.

FIG. 9 is a flowchart for explaining the power control process according to the third embodiment. First, if S101 is YES (when it is determined that power is sold from the photovoltaic power generation system 100 to the commercial power system CS), is the bidirectional DC / DC converter 33 set in the charging direction A in S110? Whether or not it is determined.

If S110 is YES (when it is determined that the bidirectional DC / DC converter 33 is set in the charging direction A at the time of selling power), whether or not the reverse power flow power WC reaches the upper limit set value WS in S111. Is determined. When S111 is NO (when it is not determined that the reverse power flow power WC reaches the upper limit set value WS), it is determined in S113 whether or not the charge conversion amount of the bidirectional DC / DC converter 33 is 0. When S113 is YES (when it is determined that the charge conversion amount is 0), the power conversion operation of the bidirectional DC / DC converter 33 is stopped (S314). Therefore, the power storage device 2 does not perform a charging operation or a discharging operation. Then, the process returns to S101.

Further, when S110 is NO (when it is not determined that the charging direction A is set at the time of selling power), it is determined in S120 whether or not the bidirectional DC / DC converter 33 is set in the discharging direction B. Will be done. When S120 is YES (when it is determined that the discharge direction B is set at the time of selling power), it is determined in S122 whether or not the storage amount wa of the power storage device 2 is equal to or less than the lower limit value wy. .. When S122 is NO (when it is not determined that wa ≦ wy), it is determined whether or not the discharge conversion amount of the bidirectional DC / DC converter 33 is 0 (S324). When it is determined that the discharge conversion amount is 0 (YES in S324), the power conversion operation of the bidirectional DC / DC converter 33 is stopped in order to stop the output of the discharge power Wd (S315). Then, the process returns to S101. If it is not determined that the discharge conversion amount is 0 (NO in S324), the discharge conversion amount of the bidirectional DC / DC converter 33 is reduced in order to suppress the output of the discharge power Wd and reduce the reverse power flow power WC. (S326). Then, the process returns to S101.

Further, when S120 is NO (when it is not determined that the charging direction B is set at the time of selling power), the bidirectional DC / DC converter 33 has stopped the power conversion operation. In this case, it is determined in S130 whether or not the reverse power flow power WC reaches the upper limit set value WS. When S130 is NO (when it is not determined that the reverse power flow power WC reaches the upper limit set value WS at the time of selling power), the process returns to S101 while the power conversion operation of the bidirectional DC / DC converter 33 remains stopped. ..

Further, when S101 is NO (when it is not determined that the power is sold), it is determined in S140 whether or not the stored amount wa of the power storage device 2 is equal to or less than the lower limit value wy. When S140 is NO (when it is not determined that wa ≦ wy), it is determined whether or not the bidirectional DC / DC converter 33 is set in the discharge direction B (S342). When it is determined that the discharge direction B is set when the power is not sold (YES in S342), the bidirectional DC / DC converter 33 is used to increase the output of the discharge power Wd and the reverse power flow power WC. The amount of discharge conversion is increased (S343). Therefore, the discharge power Wd output from the power storage device 2 to the first energization path Pa increases. Then, the process returns to S101. On the other hand, when it is not determined that the discharge direction B is set when the power is not sold (NO in S342), the bidirectional DC / DC converter 33 is set in the discharge direction B (S344). Then, the process returns to S101.

In FIG. 9, the same as that of the first embodiment (see FIG. 3) except for the above-mentioned processing. Therefore, those explanations are omitted.

Next, an example of power control of the photovoltaic power generation system 100 based on the above-mentioned power control process will be described. FIG. 10 is a graph showing an example of the daily power usage status in the third embodiment. In FIG. 10, in the time zone from 11:00 to 14:00, the power storage device 2 is charged with the power value {Wg− (WS + WL)} out of the generated power Wg.

In the time zone from 14:00 to 16:00, the photovoltaic power generation system 100 sells the reverse power flow power WC, but the power value (Wg-WL) of the reverse power flow power WC is less than the upper limit set value WS. Further, from 16:00 to 17:00, the photovoltaic power generation system 100 does not sell or buy power. Therefore, the discharge power Wd is once output to the first energization path Pa, but the power is immediately sold, and the output of the discharge power Wd becomes 0 and is stopped. Therefore, in reality, at time 16:00 to 17:00, the power storage device 2 hardly performs a discharge operation, and the discharge power Wd is hardly output to the first current-carrying path Pa. Therefore, it can be said that the power storage device 2 does not perform a charging operation or a discharging operation between the times 14:00 and 17:00.

After 17:00, the generated power Wg becomes less than the power consumption WL and the power is no longer sold, so that the power storage device 2 starts the discharge operation. Therefore, in the time zone from 17:00 to 20:00, the discharge power Wd that does not exceed the power consumption WL is output from the power storage device 2 to the first energization path Pa via the PCS3. That is, in the time zone from 17:00 to 18:00, the discharge power Wd of the power value corresponding to the difference (WL-Wg) between the power consumption WL and the generated power Wg is output and consumed in-house. Further, in the time zone from 18:00 to 20:00 when solar power generation is not possible, the discharge power Wd having the same power value as the power consumption WL is output and consumed in-house.

The discharge power Wd is not output in the time zone of FIG. 10 from 20:00 to 24:00. The reason for this is that the storage amount wa of the power storage device 2 becomes equal to or less than the lower limit value Wy around 20:00, and the discharge power Wd is no longer output from the power storage device 2.

As described above, according to the present embodiment, in the power control device 3, the power determination unit 375 detects whether or not the reverse power flow power WC is reverse power flowed from the current path P to the commercial power system CS as a detection result of the power detector M. If it is determined that the reverse power flow power WC is reverse power flow and the power value of the reverse power flow power WC does not reach the upper limit set value WS, the charge / discharge control unit 373 of the power storage device 2 When charging / discharging is stopped and it is not determined that the reverse power flow power WC is reverse power flow, the charge / discharge control unit 373 discharges the power storage device 2.

According to this configuration, when the reverse power flow power WC is not reverse power flow to the commercial power system CS (for example, in the case of power purchase, self-consumption of power, etc.), the power storage device 2 discharges the charged power, and the discharge power Wd is It is output to the energizing path P. Therefore, the power received from the commercial power system CS can be reduced or set to 0 to suppress or prevent the power purchase from the commercial power system CS.

<Fourth Embodiment>
Next, the fourth embodiment will be described. In the fourth embodiment, the generated power Wg and the discharge power Wd of the power storage device 2 are supplied to the power load system LS and consumed in-house. Further, the power storage device 2 outputs a discharge power Wd to which the reverse power flow power WC does not exceed the set power value WX. Other than these, it is the same as the third embodiment. Hereinafter, configurations different from those of the first to third embodiments will be described. Further, the same components as those in the first to third embodiments are designated by the same reference numerals, and the description thereof may be omitted.

FIG. 11 is a flowchart for explaining the power control process according to the fourth embodiment. First, when S110 is NO (when it is not determined that the charging direction A is set at the time of selling power), it is determined in S120 whether or not the bidirectional DC / DC converter 33 is set in the discharging direction B. Will be done. When S120 is YES (when it is determined that the discharge direction B is set at the time of selling power), it is determined whether or not the reverse power flow power WC (= Wg + Wd-WL) is equal to or less than the discharge power Wd. (S421). When it is not determined that WC ≦ Wd (NO in S421), it is determined that the generated power Wg is equal to or less than the power consumption WL of the power system load LS. In this case, the process proceeds to S123, and the power conversion operation of the bidirectional DC / DC converter 33 is stopped. Then, the process returns to S101.

When it is determined that WC ≦ Wd (YES in S421), it is determined in S122 whether or not the stored amount wa of the power storage device 2 is equal to or less than the lower limit value wy. When S122 is NO (when it is not determined that wa ≦ wy), it is determined whether or not the reverse power flow power WC reaches the set power value WX (S424). This set power value WX is a value for setting an upper limit of the power value to be sold to the commercial power system CS during the period when the power storage device 2 is discharged, and is a value less than the upper limit set value WS (that is, 0 <WX). It is set to <WS). The setting information of the set power value WX is stored in the storage unit 36.

When it is determined that the reverse power flow power WC reaches the set power value WX (YES in S424), it is determined whether or not the discharge conversion amount of the bidirectional DC / DC converter 33 is 0 (S425). When it is determined that the discharge conversion amount is 0 (YES in S425), the power conversion operation of the bidirectional DC / DC converter 33 is stopped in order to stop the output of the discharge power Wd (S426). Then, the process returns to S101. If it is not determined that the discharge conversion amount is 0 (NO in S425), the discharge conversion amount of the bidirectional DC / DC converter 33 is reduced in order to suppress the output of the discharge power Wd and reduce the reverse power flow power WC. (S427). Then, the process returns to S101.

If it is not determined that the reverse power flow power WC reaches the set power value WX (NO in S424), the bidirectional DC / DC converter 33 is discharged in order to increase the output of the discharge power Wd and increase the reverse power flow power WC. The amount of conversion is increased (S428). Therefore, the discharge power Wd output from the power storage device 2 to the first energization path Pa increases. Then, the process returns to S101.

In the power control process described above, in the process of S421 in FIG. 11, whether or not the generated power Wg is equal to or less than the power consumption WL by determining whether or not the reverse power flow power WC is equal to or less than the discharge power Wd. However, it may be directly determined whether or not the generated power Wg is equal to or less than the power consumption WL. In this case, a power detection unit that detects the power value of the generated power Wg may be built in the solar cell string 1, or may be provided in the energization path between the solar cell string 1 and the PCS 3.

Further, in FIG. 11, the same as the third embodiment (see FIG. 9) except for the above-mentioned processing. Therefore, those explanations are omitted.

Next, an example of power control of the photovoltaic power generation system 100 based on the above-mentioned power control process will be described. FIG. 12 is a graph showing an example of the daily power usage status in the fourth embodiment. In FIG. 12, in the time zone from 11:00 to 14:00, the power storage device 2 is charged with the power value {Wg− (WS + WL)} out of the generated power Wg. Further, in the time zone from 14:00 to 16:00, the photovoltaic power generation system 100 sells the reverse power flow power WC, but the power value (Wg-WL) of the reverse power flow power WC is less than the upper limit set value WS. is there. Therefore, at time 14:00 to 16:00, the power storage device 2 does not perform a charging operation or a discharging operation.

After 16:00 of the time, the generated power Wg becomes a power value substantially the same as the power consumption WL, and the power selling state is not reached. Therefore, the power storage device 2 starts the discharging operation. In the time zone from 16:00 to 19:00, the discharge power Wd to which the reverse power flow power WC does not exceed the set power value WX is output from the power storage device 2 to the first current-carrying path Pa via the PCS3. That is, the discharge power Wd of the power value corresponding to the sum of the difference (WL-Wg) between the power consumption WL and the generated power Wg and the set power value WX {(WL-Wg) + WX} is output.

Therefore, in the time zone from 17:00 to 18:00, the discharge power Wd having the same power value as the set power value WX is output to the first energization path Pa, and the power having the same power value as the set power value WX is the reverse power flow power. Power is sold to the commercial power system CS as WC. In the time zone from 18:00 to 19:00, the discharge power Wd of the power value {(WL-Wg) + WX} is output to the first current-carrying path Pa. Then, of the power obtained by adding the discharge power Wd to the generated power Wg, the power having the power value (WL-Wg) is consumed in-house, and the power having the same power value as the set power value WX is used as the reverse power flow power WC for the commercial power system CS. Power is sold to. Further, in the time zone from 18:00 to 19:00 when solar power generation is not possible, of the discharge power Wd, the power having the same power value as the power consumption WL is consumed in-house, and the power having a power value less than the set power value WX is reversed. It is sold to the commercial power system CS as power flow WC.

In the time zone of FIG. 12 from 18:00 to 19:00, the reverse power flow power WC is smaller than the set power value WX. Further, the discharge power Wd is not output from the power storage device 2 in the time zone from 19:00 to 24:00. These reasons are that the electricity storage amount wa of the electricity storage device 2 becomes equal to or less than the lower limit value Wy around 19:00, and the discharge power Wd is no longer output.

As described above, according to the present embodiment, in the power control device 3, the power determination unit 375 determines whether or not the reverse power flow power WC is reversely flowing from the energization path P to the commercial power system CS, and the charge / discharge control unit 373 stores electricity. Whether or not the power value of the reverse power flow power WC is equal to or less than the discharge power Wd when the device 2 is being discharged, and the power value of the reverse power flow power WC when the charge / discharge control unit 373 is discharging the power storage device 2. Further determines whether or not the set power value WX less than the upper limit set value WS is reached based on the detection result of the power detector M, and the reverse power flow is performed when the charge / discharge control unit 373 discharges the power storage device 2. When the power WC is backflowed to the commercial power system CS and the backflow power WC is determined to be equal to or less than the discharge power Wd, the charge / discharge control unit 373 determines that the power value of the backflow power WC exceeds the set power value WX. The power storage device 2 is discharged so as not to be present.

According to this configuration, it is possible to suppress or prevent the purchase of power from the commercial power system CS, and it is also possible to sell the discharge power Wd less than the set power value WX to the commercial power system CS.

<Fifth Embodiment>
Next, the fifth embodiment will be described. In the fifth embodiment, the charging / discharging of the power storage device 2 is controlled by the power conversion operation of the bidirectional inverter 32. Hereinafter, configurations different from those of the first to fourth embodiments will be described. Further, the same components as those in the first to fourth embodiments are designated by the same reference numerals, and the description thereof may be omitted.

FIG. 13 is a block diagram showing a second configuration example of the photovoltaic power generation system 100. In the photovoltaic power generation system 100, the solar cell string 1 is connected to one end of the third current-carrying path Pc via the backflow prevention device 11. The backflow prevention device 11 is composed of, for example, a circuit including a rectifying element such as a diode, and prevents a backflow current from flowing through the solar cell string 1. A DC / DC converter 31 may be provided instead of the backflow prevention device 11.

A power storage device 2 is also connected to one end of the third current-carrying path Pc. Further, the input / output end of the power storage device 2 is connected in parallel with the output end of the backflow prevention device 11. Therefore, the power generation of the solar cell string 1 is controlled so that its operating point voltage becomes the same voltage value as the input / output voltage of the power storage device 2. The number of solar cell strings 1 provided in the photovoltaic power generation system 100 is not limited to the example shown in FIG. 13, and may be plural. For example, a plurality of solar cell strings 1 connected in parallel to each other may be connected to the PCS 3 via a third current-carrying path Pc. Further, the plurality of solar cell strings 1 may be connected to the PCS 3 via the third current-carrying path Pc by the same connection method as in FIG. 2A or FIG. 2B. In this case, each solar cell string 1 may be individually connected to the PCS 3 via the backflow prevention device 11.

The PCS3 is connected to the other end of the third current path Pc. As shown in FIG. 13, the PCS3 has a bidirectional inverter 32, a communication unit 35, a storage unit 36, and a control unit 37. In the bidirectional inverter 32, the bidirectional inverter 32 is connected between the other end of the third energization path Pc and the first energization path Pa. When the bidirectional inverter 32 performs the reverse conversion operation, the bidirectional inverter 32 converts the DC power input from the third current-carrying path Pc into AC power and outputs it to the first current-carrying path Pa. This DC power includes at least one of the generated power Wg and the discharge power Wd of the power storage device 2.

Although the second configuration example of the photovoltaic power generation system 100 has been described above based on FIG. 13, the configuration of the photovoltaic power generation system 100 is not limited to the example of FIG. FIG. 14 is a block diagram showing a modified example of the second configuration example of the photovoltaic power generation system. As shown in FIG. 14, a bidirectional DC / DC converter 33 may be provided between the power storage device 2 and the third current-carrying path Pc. In this way, the charge / discharge function of the power storage device 2 can be controlled by controlling the power conversion of the bidirectional DC / DC converter 33.

Further, although the solar cell string 1 is used as the power generation device in FIGS. 13 and 14, the power generation device is not limited to these examples. A power generation device that generates power using renewable energy other than solar power (wind power, hydropower, geothermal power, biomass, natural energy power generation such as solar heat, waste power generation, etc.) may be used. For example, the wind power generation system 100 may use the wind power generation device 1 as the power generation device. In this case, the wind power generator 1 is connected to the PCS 3 via an AD / DC converter.

Next, the power control method of the photovoltaic power generation system 100 will be described. FIG. 15 is a flowchart for explaining the power control process according to the fifth embodiment. In FIG. 15, in the case of selling power, the bidirectional inverter 32 is set in the reverse conversion direction b. This also applies to other figures described later (for example, FIGS. 16 and 17).

First, it is determined whether or not the reverse power flow power WC is reverse power flowed from the photovoltaic power generation system 100 to the commercial power system CS and sold (S501). If it is not determined that the power is sold (NO in S501), the process proceeds to S540 described later. When it is determined that the power is sold (YES in S501), it is determined whether or not the charging power is input to the power storage device 2 (S510). If it is not determined that the charging power is input (NO in S510), the process proceeds to S520 described later.

When it is determined that the charging power is input (YES in S510), it is determined whether or not the reverse power flow power WC reaches the upper limit set value WS (S511). When it is determined that the reverse power flow power WC reaches the upper limit set value WS (YES in S511), the reverse conversion amount of the bidirectional inverter 32 is reduced in order to reduce the reverse power flow power WC (S512). Therefore, of the generated power Wg, the charging power supplied to the power storage device 2 is large, and the power output to the first current-carrying path Pa is small. Then, the process returns to S501.

When it is not determined that the reverse power flow power WC reaches the upper limit set value WS (NO in S511), the reverse conversion amount of the bidirectional inverter 32 is increased in order to increase the reverse power flow power WC (S515). Therefore, of the generated power Wg, the charging power supplied to the power storage device 2 is small, and the power output to the first current-carrying path Pa is large. Then, the process returns to S501.

Next, when S510 is NO (when it is not determined that the charging power is input to the power storage device 2 at the time of selling power), it is determined whether or not the discharge power Wd is output from the power storage device 2 (when it is not determined). S520). If it is not determined that the discharge power Wd is output (NO in S520), the process proceeds to S530 described later. When it is determined that the discharge power Wd is output (YES in S520), it is determined whether or not the electricity storage amount wa of the electricity storage device 2 is equal to or less than the lower limit value wy (S522). The lower limit value wy is a value indicating that the storage amount wa of the power storage device 2 is small (for example, a state close to 0 [W]). The lower limit value wy is set within the range of 0 or more and less than the storage capacity wr (0 ≦ wy <wr), but it is more preferably set by 0 <wy <wr. If the discharge operation is performed in a state where the amount of electricity stored in the power storage device 2 is small (for example, a state close to 0 [W]), the charge / discharge function of the power storage device 2 tends to deteriorate. Therefore, if the power storage device 2 is prevented from discharging in such a case, deterioration of the charge / discharge function can be suppressed or prevented.

When it is determined that wa ≦ wy (YES in S522), the power storage device 2 does not perform the charging operation and does not perform the discharging operation in a state where the storage amount wa is small (for example, a state close to 0 [W]). The reverse conversion operation of the bidirectional inverter 32 is controlled. That is, by controlling the power conversion operation of the bidirectional inverter 32, the charging / discharging operation of the power storage device 2 is substantially stopped. Specifically, the amount of inverse conversion of the bidirectional inverter 32 is reduced (S523), and it is determined again whether or not the discharge power Wd is output from the power storage device 2 (S524). When it is determined that the discharge power Wd is output (YES in S524), the process returns to S523. When it is not determined that the discharge power Wd is output (NO in S524), it is determined whether or not the charge power is input to the power storage device 2 (S525). When it is determined that the charging power is input to the power storage device 2 (YES in S525), the inverse conversion amount of the bidirectional inverter 32 is increased (S526), and the process returns to S523. When it is not determined that the charging power is input to the power storage device 2 (NO in S525), the power storage device 2 is in a state in which the charge / discharge operation is almost not performed. Then, the process returns to S501.

If it is not determined that wa ≦ wy (NO in S522), it is determined whether or not the reverse power flow power WC reaches the upper limit set value WS (S527). When it is determined that the reverse power flow power WC reaches the upper limit set value WS (YES in S527), the reverse conversion amount of the bidirectional inverter 32 is reduced in order to reduce the reverse power flow power WC (S528). Therefore, the discharge power Wd output from the power storage device 2 to the first energization path Pa is reduced. Then, the process returns to S501.

When it is not determined that the reverse power flow power WC reaches the upper limit set value WS (NO in S527), the reverse conversion amount of the bidirectional inverter 32 is increased in order to increase the reverse power flow power WC (S529). Therefore, the discharge power Wd output from the power storage device 2 to the first energization path Pa increases. Then, the process returns to S501.

Next, when S520 is NO (when it is not determined that the discharge power Wd is output from the power storage device 2 at the time of selling power), it is determined whether or not the reverse power flow power WC reaches the upper limit set value WS. (S530). If it is not determined that the reverse power flow power WC reaches the upper limit set value WS (NO in S530), the process proceeds to S540 described later. When it is determined that the reverse power flow power WC reaches the upper limit set value WS (YES in S530), the reverse conversion amount of the bidirectional inverter 32 is reduced until the power storage device 2 starts the charging operation. That is, the amount of inverse conversion of the bidirectional inverter 32 is reduced (S531), and it is determined whether or not the charging power is input to the power storage device 2 (S532). If it is not determined that the charging power is input (NO in S532), the process returns to S531. When it is determined that the charging power is input (YES in S532), the process returns to S501.

Next, in the case of NO in S501 (when it is not determined that the power is sold) and in the case of NO in S530 (when it is not determined that the reverse power flow power WC reaches the upper limit set value WS at the time of power sale), It is determined whether or not the electricity storage amount wa of the electricity storage device 2 is equal to or less than the lower limit value wy (S540). When it is determined that wa ≦ wy (YES in S540), the power storage device 2 does not perform the charging operation and does not perform the discharging operation in a state where the storage amount wa is small (for example, a state close to 0 [W]). The reverse conversion operation of the bidirectional inverter 32 is controlled. That is, by controlling the power conversion operation of the bidirectional inverter 32, the charging / discharging operation of the power storage device 2 is substantially stopped. Specifically, it is determined whether or not the discharge power Wd is output from the power storage device 2 (S541). When it is determined that the discharge power Wd is being output (YES in S541), the inverse conversion amount of the bidirectional inverter 32 is reduced (S542), and the process returns to S541. When it is not determined that the discharge power Wd is output (NO in S541), it is determined whether or not the charge power is input to the power storage device 2 (S543). When it is determined that the charging power is input to the power storage device 2 (YES in S543), the inverse conversion amount of the bidirectional inverter 32 is increased (S544), and the process returns to S541. When it is not determined that the charging power is input to the power storage device 2 (NO in S543), the power storage device 2 is in a state in which the charge / discharge operation is almost not performed. Then, the process returns to S501.

Further, when it is not determined that wa ≦ wy (NO in S540), the inverse conversion amount of the bidirectional inverter 32 is reduced until the power storage device 2 starts the discharge operation. That is, the amount of inverse conversion of the bidirectional inverter 32 is increased (S545), and it is determined whether or not the discharge power Wd is output from the power storage device 2 (S546). If it is not determined that the discharge power Wd is being output (NO in S546), the process returns to S545. When it is determined that the discharge power Wd is output (YES in S545), the process returns to S501.

According to the above power control process, the same power control as in FIG. 4 can be performed. In the power control process of FIG. 15, the upper limit set value WS is set to a value of 1, but as in the second embodiment (see FIG. 8), for example, every predetermined period (for example, a time zone of one day). It may include a plurality of upper limit setting values set every day, every day of the week, every week, every month, and so on. In this case, in the above-mentioned power control process, a process in which the current time is clocked between S501 and S510 (see S202 in FIG. 7) and an upper limit set value WS corresponding to the time zone including the current time are determined. It suffices to have a process (see S203 in FIG. 7). In this way, more detailed power control can be performed according to the actual power generation amount of the solar cell string 1 that fluctuates depending on the environmental conditions and the like, and the actual operating status of the commercial power system CS.

<Sixth Embodiment>
Next, the sixth embodiment will be described. In the sixth embodiment, the generated power Wg and the discharge power Wd of the power storage device 2 are supplied to the power load system LS and consumed in-house, but are not sold to the commercial power system CS. Other than this, it is the same as the fifth embodiment. Hereinafter, configurations different from those of the first to fifth embodiments will be described. Further, the same components as those in the first to fifth embodiments are designated by the same reference numerals, and the description thereof may be omitted.

FIG. 16 is a flowchart for explaining the power control process according to the sixth embodiment. First, when S501 is YES (when it is determined that the power is sold from the photovoltaic power generation system 100 to the commercial power system CS), it is determined in S510 whether or not the charging power is input to the power storage device 2. To.

When S510 is NO (when it is not determined that the charging power is input at the time of selling the power), it is determined in S520 whether or not the discharge power Wd is output from the power storage device 2. When S520 is YES (when it is determined that the discharge power Wd is output at the time of selling power), the processes of S523 to S526 are performed. By these processes, the reverse conversion operation of the bidirectional inverter 32 is controlled so that the power storage device 2 does not perform the charging operation and does not perform the discharging operation in a state where the storage amount wa is small (for example, a state close to 0 [W]). To. Then, the process returns to S501.

Further, when S520 is NO (when it is not determined that the discharge power Wd is output at the time of selling power), it is determined in S530 whether or not the reverse power flow power WC reaches the upper limit set value WS. If S530 is NO (when it is not determined that the reverse power flow power WC reaches the upper limit set value WS), the process proceeds to S524. Then, the processes of S523 to S526 are performed as described above. By these processes, the reverse conversion operation of the bidirectional inverter 32 is controlled so that the power storage device 2 does not perform the charging operation and does not perform the discharging operation when the storage amount wa is small (for example, a state close to 0 [W]). To. Then, the process returns to S501.

If S530 is YES (when it is determined that the reverse power flow power WC reaches the upper limit set value WS at the time of selling power), the processes of S531 and S532 are performed. By these processes, the amount of inverse conversion of the bidirectional inverter 32 is reduced until the power storage device 2 starts the charging operation. Then, the process returns to S501.

Further, when NO in S501 (when it is not determined that the power is sold), it is determined in S540 whether or not the stored amount wa of the power storage device 2 is equal to or less than the lower limit value wy. When S540 is YES (when it is determined that wa ≦ wy), the processes of S541 to S544 are performed. By these processes, the reverse conversion operation of the bidirectional inverter 32 is controlled so that the power storage device 2 does not perform the charging operation and does not perform the discharging operation when the storage amount wa is small (for example, a state close to 0 [W]). To. Then, the process returns to S501.

Further, when S540 is NO (when it is not determined that wa ≦ wy), the processes of S545 and S546 are performed. By these processes, the amount of inverse conversion of the bidirectional inverter 32 is reduced until the power storage device 2 starts the discharge operation. Then, the process returns to S501.

In FIG. 16, the same as the fifth embodiment (see FIG. 15) except for the above-mentioned processing. Therefore, those explanations are omitted.

According to the above power control process, the same power control as in FIG. 10 can be performed.

<7th Embodiment>
Next, the seventh embodiment will be described. In the seventh embodiment, the generated power Wg and the discharge power Wd of the power storage device 2 are supplied to the power load system LS and consumed in-house. Further, the power storage device 2 outputs a discharge power Wd to which the reverse power flow power WC does not exceed the set power value WX. Other than these, it is the same as the sixth embodiment. Hereinafter, configurations different from those of the first to sixth embodiments will be described. Further, the same components as those in the first to sixth embodiments are designated by the same reference numerals, and the description thereof may be omitted.

FIG. 17 is a flowchart for explaining the power control process according to the seventh embodiment. When S510 is NO (when it is not determined that the charging power is input to the power storage device 2 at the time of selling power), whether or not the bidirectional DC / DC converter 33 is set in the discharge direction B in S520 It is judged. When S520 is YES (when it is determined that the discharge direction B is set at the time of selling power), it is determined whether or not the reverse power flow power WC (= Wg + Wd-WL) is equal to or less than the discharge power Wd. (S721). In the process of S721, it is determined whether or not the generated power Wg is equal to or less than the power consumption WL of the power system load LS.

When it is determined that WC ≦ Wd (YES in S721), it is determined in S522 whether or not the stored amount wa of the power storage device 2 is equal to or less than the lower limit value wy. When S522 is NO (when it is not determined that wa ≦ wy), it is determined whether or not the reverse power flow power WC reaches the set power value WX (S727). This set power value WX is a value for setting an upper limit of the power value to be sold to the commercial power system CS during the period when the power storage device 2 is discharged, and is a value less than the upper limit set value WS (that is, 0 <WX). It is set to <WS). The setting information of the set power value WX is stored in the storage unit 36.

When it is determined that the reverse power flow power WC reaches the set power value WX (YES in S727), the reverse conversion amount of the bidirectional inverter 32 is reduced in order to suppress the output of the discharge power Wd and reduce the reverse power flow power WC. (S728). Then, the process returns to S501. If it is not determined that the reverse power flow power WC reaches the set power value WX (NO in S727), the reverse conversion amount of the bidirectional inverter 32 is increased in order to increase the output of the discharge power Wd and increase the reverse power flow power WC. Increase (S729). Therefore, the discharge power Wd output from the power storage device 2 to the first energization path Pa increases. Then, the process returns to S501.

On the other hand, when S522 is YES (when it is determined that wa ≦ wy) or S721 is NO (when it is not determined that WC ≦ Wd), the processes of S523 to S526 are performed. By these processes, the reverse conversion operation of the bidirectional inverter 32 is controlled so that the power storage device 2 does not perform the charging operation and does not perform the discharging operation in a state where the storage amount wa is small (for example, a state close to 0 [W]). To. Then, the process returns to S501.

In the power control process described above, in the process of S721 in FIG. 17, whether or not the generated power Wg is equal to or less than the power consumption WL by determining whether or not the reverse power flow power WC is equal to or less than the discharge power Wd. However, it may be directly determined whether or not the generated power Wg is equal to or less than the power consumption WL. In this case, a power detection unit that detects the power value of the generated power Wg may be built in the solar cell string 1, or may be provided in the energization path between the solar cell string 1 and the PCS 3.

Further, in FIG. 17, the same as the sixth embodiment (see FIG. 16) except for the above-mentioned processing. Therefore, those explanations are omitted.

According to the above power control process, the same power control as in FIG. 12 can be performed.

The embodiment of the present invention has been described above. It should be noted that the above-described embodiment is an example, and various modifications can be made to the combination of each component and each process, and it is understood by those skilled in the art that it is within the scope of the present invention.

For example, although the power control methods in the first configuration example of the photovoltaic power generation system 100 exemplified in the above-described first to fourth embodiments are different, any one of these power control methods is adopted. Alternatively, two or more of these power control methods may be adopted so as to be switchable by user input or the like. The same applies to the power control method in the second configuration example of the photovoltaic power generation system 100 exemplified in the fifth to seventh embodiments described above.

Further, in the above-mentioned first to seventh embodiments, the PCS3 has the bidirectional inverter 32, but the present invention is not limited to this example. When the power storage device 2 is not charged with the power received from the commercial power system CS, the PCS 3 may include an inverter (power conversion unit) that converts power in the reverse conversion direction b instead of the bidirectional inverter 32.

Further, in the above-described first to seventh embodiments, an AC power source such as a commercial power system CS is connected to the photovoltaic power generation system 100, but the present invention is not limited to this example. Instead of the commercial power system CS, a DC power source may be connected to the photovoltaic power generation system 100. In this case, the PCS 3 can be configured to have a DC / DC converter or a bidirectional DC / DC converter instead of the bidirectional inverter 32.

Further, in the first to seventh embodiments described above, at least a part or all of the functional components 371 to 375 of the control unit 37 are physical components (for example, an electric circuit, an element, an apparatus, etc.). It may be realized by.

100 Photovoltaic power generation system, Wind power generation system 1 Solar cell string, Wind power generation device 11 Backflow prevention device 12 Junction box 13 DC / AC converter 2 Power storage device 21 Input / output power detector 3 Power conditioner (PCS)
31 DC / DC converter 32 Bidirectional inverter 33 Bidirectional DC / DC converter 34 Smoothing capacitor 35 Communication unit 36 Storage unit 37 Control unit 371 Power monitoring unit 372 Power storage monitoring unit 373 Conversion control unit 374 Timer 375 Power judgment unit 38 AD / DC Converter 4 Controller 41 Display 42 Input 43 Communication 44 Control BL Bus line P Current path Pa, Pb 1st to 2nd current path Pc 3rd current path M Electricity meter CS Commercial power system LS Power load system

Claims (5)

A power conversion unit that converts at least one of the generated power of the power generation device and the discharge power of the power storage device and outputs it to the energization path connected to the commercial power system.
Power determination for determining whether or not the power value of the reverse power flow reaches the upper limit set value based on the detection result of the power detector that detects the reverse power flow from the current-carrying path to the commercial power system. Department and
A charge / discharge control unit that controls the charge / discharge of the power storage device,
With
The upper limit setting value is plural, and one of the upper limit setting values is set in association with each of a plurality of time zones of the day.
When it is determined that the power value of the reverse power flow power reaches the upper limit set value, the charge / discharge control unit charges the power storage device with at least a part of the generated power.
When it is not determined that the power value of the reverse power flow power reaches the upper limit set value, the charge / discharge control unit outputs discharge power from the power storage device so that the power value of the reverse power flow power does not exceed the upper limit set value. At the same time, the discharge power is reverse power flowed to the commercial power system .
The upper limit set value associated with daytime the time zone, set Ru power controller lower than the upper limit set value associated with nighttime the time zone. The power control device according to claim 1, wherein the upper limit set value including noon and associated with the time zone after noon is set to be the lowest. The power value of the discharge power is the value according to the difference between the power value of the power that can reverse power flow to the commercial power system and the upper limit set value of the generated power, according to claim 1 or 2 . Power control device. When it is not determined that the power value of the reverse power flow power reaches the upper limit set value, the power value of the reverse power flow power is set by the charge / discharge control unit with the set power value less than the upper limit set value as the upper limit of the discharge power. The discharge power is output from the power storage device so as not to exceed the set power value, and the discharge power is reverse-fed to the commercial power system.
The power value of the discharge power is the value according to the difference between the power value of the power that can be reverse-powered to the commercial power system and the set power value of the generated power, according to claim 1 or 2 . Power control device. A step in which at least one of the generated power of the power generation device and the discharge power of the power storage device is converted into power and output to an energization path connected to the commercial power system.
The step of detecting the power value of the reverse power flow from the current-carrying circuit to the commercial power system, and
A step in which it is determined whether or not the power value of the reverse power flow power reaches the upper limit set value based on the detection result in the detected step.
A step in which charging / discharging of the power storage device is controlled,
With
The upper limit setting value is plural, and one of the upper limit setting values is set in association with each of a plurality of time zones of the day.
The step in which charging / discharging is controlled is
A step of charging the power storage device with at least a part of the generated power when it is determined that the power value of the reverse power flow power reaches the upper limit set value.
When it is not determined that the power value of the reverse power flow power reaches the upper limit set value, the discharge power is output from the power storage device so that the power value of the reverse power flow power does not exceed the upper limit set value, and the discharge power is output. a step of discharging power is reverse power flow to the commercial power system, only including,
A power control method in which the upper limit set value associated with the time zone in the daytime is set lower than the upper limit set value associated with the time zone at night .

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