JP5836164B2 - Solar power system - Google Patents

Description

  The present invention relates to a photovoltaic power generation system.

  Since a solar power generation system is a system in which solar cells generate power by receiving sunlight, it cannot generate power at night, and the amount of power generation depends greatly on the amount of solar radiation, in other words, the weather.

  On the other hand, Patent Document 1 describes that a photovoltaic power generation inverter system is provided with a battery and is operated in parallel. Specifically, in a photovoltaic power generation inverter system, DC power from a solar cell is converted to a constant voltage by a DC / DC converter, converted to AC power by a DC / AC converter, and supplied to a load via a high-speed switch. In this configuration, the battery is connected to a DC circuit between the DC / DC converter and the DC / AC converter, and the charge / discharge state of the battery is constantly monitored by the control system via the current transformer. Then, when it is detected that the battery is in a charged state, DC power output from the solar cell is supplied to the load and charged to the battery, and when it is detected that the battery is in a discharged state, DC power from the solar cell is supplied to the load, and DC power is also supplied from the battery to the load. Thus, according to Patent Document 1, since the output fluctuation of the photovoltaic power generation is absorbed and stabilized by the discharge of the battery, the power supplied from the photovoltaic power generation can be stabilized.

JP-A-8-223816

  In the technique described in Patent Document 1, it is considered that power is supplied from the commercial power supply side to the load if the output from the solar cell including the battery is small. For this reason, for example, it may be necessary to largely depend on the power supply from the commercial power supply side in a time zone in which power consumption from evening to bedtime is highest during the day. The use of power (system AC power) from may be concentrated during a specific time period. That is, it is difficult to level the use of grid AC power. As a result, a large amount of grid AC power is consumed in a time zone where there is no discount on the electricity charge, and the electricity charge may increase.

  This invention is made | formed in view of the above, Comprising: It aims at obtaining the solar power generation system which can level | level use of system | strain AC power.

  In order to solve the above-described problems and achieve the object, a photovoltaic power generation system according to one aspect of the present invention converts a solar cell and DC power generated by the solar cell into DC power of a predetermined level. A DC / DC converter, a DC / AC inverter that converts the converted DC power into AC power, an AC / DC converter that converts system AC power into DC power, a secondary battery, and charging of the secondary battery A charge / discharge control unit that controls discharge, and a charge amount calculation unit that calculates a target charge amount to the secondary battery, wherein the charge amount calculation unit is based on an expected value of power usage per day The target charge amount is calculated, and the charge / discharge control unit charges the secondary battery from the grid AC power via the AC / DC converter at midnight based on the calculated target charge amount, and daytime In Serial via the DC / DC converter from the solar cell and controls to charge the secondary battery.

  According to the present invention, power is supplied mainly from the secondary battery to the load in a time zone where the power usage by the load is large (for example, evening time zone), so that the usage amount of the system AC power can be reduced, and the power from the load can be reduced. Since the secondary battery is charged using the grid AC power in a time zone where the usage volume is small (for example, at midnight power hours), the grid AC power usage can be suppressed to a necessary limit. That is, the use of grid AC power can be leveled.

FIG. 1 is a diagram illustrating the configuration of the photovoltaic power generation system according to the first embodiment. FIG. 2 is a diagram showing a power usage pattern in the first embodiment. FIG. 3 is a diagram illustrating a configuration of the charge amount calculation unit in the first embodiment. FIG. 4 is a diagram illustrating a configuration of the photovoltaic power generation system according to the second embodiment.

  Embodiments of a photovoltaic power generation system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to these embodiments.

Embodiment 1 FIG.
A photovoltaic power generation system 100 according to the first embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a solar power generation system 100.

  The solar power generation system 100 is installed on, for example, a roof of a house and receives power to generate power. That is, since the solar power generation system 100 is a system in which the solar battery 7 generates power upon receiving sunlight, it cannot generate power at all at night, and the power generation amount is greatly influenced by the amount of solar radiation, in other words, the weather. In the solar power generation system 100, when such a power generation amount is small or no power is generated at all, power (system AC power) is supplied from the commercial system power supply SP to a load (for example, a load in a house) LD. Further, in the solar power generation system 100, in preparation for an emergency such as a stop of the commercial power supply SP such as a disaster, a secondary battery 8 is added, and discharge power (DC power) from the secondary battery 8 is added. Is converted into AC power and supplied to the load LD.

  In the photovoltaic power generation system 100 including such a secondary battery 8, power is supplied to the load LD from the solar battery 7 side including the secondary battery 8, and power (system) is supplied from the commercial power supply SP side to the load LD. It is also conceivable to perform control to switch the case of supplying (AC power) based on the charge / discharge state of the secondary battery 8.

  However, in such control, it is considered that power (system AC power) is supplied from the commercial system power supply SP side to the load LD if the output from the solar battery 7 including the secondary battery 8 is small. For this reason, for example, it may be necessary to largely depend on the power supply from the commercial power supply SP in a time zone in which the power consumption from evening to before bedtime is the largest in the day. The use of power (system AC power) from the power supply SP may be concentrated in a specific time zone. That is, it is difficult to level the use of grid AC power. As a result, for example, a large amount of grid AC power is consumed in a time zone in which there is no discount on the electricity charge, so that the electricity charge may increase.

  Here, in the photovoltaic power generation system 100 provided with the secondary battery 8, if power is not sold, the surplus generated power portion B in the daytime is stored in the secondary battery 8 as shown in FIG. Consider the case of use in part D. In this case, at time T, the secondary battery 8 mainly stores the power of the surplus generated power portion B during the daytime, but the secondary battery 8 is still charged with power. In many cases, there is a margin for storage.

  Therefore, in the present embodiment, the leeway power of the secondary battery 8 is charged as shown by the charging part F using the midnight power of the previous day and is used in the peak consumption part D, so that the midnight power can be efficiently obtained. Aim to use. In other words, as a basic control method, charging is performed using grid AC power during the electricity rate discount time period, and the grid AC power consumption during the time period when there is no electricity rate discount is used as a basic control method. Then, the secondary battery 8 is charged as shown by the charging portion F in the midnight power time zone of the previous day so that the secondary battery 8 is fully charged or close to it. This will be specifically described below.

  As shown in FIG. 1, the photovoltaic power generation system 100 includes a solar cell 7, a DC / DC converter 1, a distributor 11, a DC / AC inverter 2, a combiner / distributor 12, an AC / DC converter 4, a current sensor 5, And a control circuit 6.

  The solar cell 7 receives sunlight and generates power to generate DC power. The solar cell 7 supplies the generated DC power to the DC / DC converter 1.

  The DC / DC converter 1 receives direct current power generated by the solar cell 7. The DC / DC converter 1 converts the DC power into a predetermined level of DC power by stepping up or down the DC power under the control of the control circuit 6.

  For example, the DC / DC converter 1 includes a reactor 1a, a switching element 1b, and a diode 1c. The current flowing through the reactor 1a is controlled by the duty ratio between the ON time and the OFF time of the switching element 1b under the control of the control circuit 6, and the energy stored in the reactor 1a is output via the diode 1c. . As a result, the DC / DC converter 1 converts the DC power into a predetermined level of DC power. The predetermined level (voltage value) is set as a value suitable for generating the level (voltage value) of AC power converted by the DC / AC inverter 2.

  The DC / DC converter 1 supplies the converted DC power to the distributor 11.

  Distributor 11 receives DC power from DC / DC converter 1. The distributor 11 distributes DC power from the DC / DC converter 1 to the DC / AC inverter 2 and the secondary battery 8 (via the charge meter 3) under the control of the control circuit 6.

  That is, the DC / DC converter 1 also charges the secondary battery 8 connected via the distributor 11 and the charge meter 3.

  The charge meter 3 is used to perform charge / discharge control for setting the secondary battery 8 to a target charge amount. This charge / discharge control is performed by the control circuit 6 as described later.

  The DC / AC inverter 2 receives direct current power from the distributor 11. The DC / AC inverter 2 converts direct current power into alternating current power.

  For example, the DC / AC inverter 2 includes a plurality of switching elements 2a to 2b. The plurality of switching elements 2 a to 2 b are turned on / off at a predetermined timing under the control of the control circuit 6. Thereby, the DC / AC inverter 2 converts DC power into AC power.

  The combiner / distributor 12 receives the converted AC power from the DC / AC inverter 2 and receives the grid AC power from the commercial grid power supply SP. The combiner / distributor 12 controls a power path among the DC / AC inverter 2, the commercial power supply SP, the AC / DC converter 4, and the load LD under the control of the control circuit 6.

  For example, the synthesizer / distributor 12 synthesizes AC power received from the DC / AC inverter 2 and system AC power received from the commercial power supply SP under the control of the control circuit 6, or loads AC power. Or distributed to the secondary battery 8 (via the AC / DC converter 4 and the charge meter 3).

  The AC / DC converter 4 receives, for example, system AC power from the combiner / distributor 12. For example, the AC / DC converter 4 converts system AC power into DC power and charges the secondary battery 8.

  The current sensor 5 is provided on a distribution board or the like. For example, the direction of power is “commercial system power supply SP → solar power generation system 100” (power purchase) or “solar power generation system 100 → commercial system power supply SP” (sold) ) Is detected.

  The current sensor 5 may detect the usage amount of the system AC power. That is, the current sensor 5 may detect a daily power usage pattern under the control of the control circuit 6. For example, the current sensor 5 may detect the amount of grid AC power used at each time of day.

  The control circuit 6 controls each part in the photovoltaic power generation system 100 as a whole. For example, the control circuit 6 acquires the power usage pattern PC and the power generation pattern EG as shown in FIG. 2 in advance, and at the time T, the midnight power of the previous day is set so that the secondary battery 8 is fully charged or close to it. Each unit is controlled so as to be charged as indicated by the charging portion F according to the charging pattern BC in the time zone.

  For example, the control circuit 6 includes a storage unit 62, a charge amount calculation unit 61, and a charge / discharge control unit 63.

  The storage unit 62 stores, for example, a power usage pattern PC and a power generation pattern EG (see FIG. 2). The power usage pattern PC represents how much power is consumed by the load LD at each time of day. The power generation pattern EG represents how much power is generated by the solar cell 7 at each time of the day.

  The power usage pattern PC and the power generation pattern EG may be experimentally acquired in advance and stored in the storage unit 62. At least one of the power usage pattern PC and the power generation pattern EG may be a solar power generation system. It may be stored by being corrected and updated as necessary by the control circuit 6 during operation of 100.

  The charge amount calculation unit 61 calculates a target charge amount for the secondary battery 8. The charge amount calculation unit 61 refers to the storage unit 62, for example, and predicts the daily power consumption. The charge amount calculation unit 61 calculates a target charge amount based on the predicted value of the daily power consumption. For example, the charge amount calculation unit 61 calculates the target charge amount so that the supply amount of the grid AC power to the load LD in a day is smaller than the current supply amount of the grid AC power. The charge amount calculation unit 61 supplies the calculated target charge amount to the charge / discharge control unit 63.

  In addition, the charge amount calculation unit 61 may correct the power usage pattern PC according to the detection result by the current sensor 5, for example.

  For example, when the power usage pattern PC is corrected by the charge amount calculation unit 61 during the operation of the photovoltaic power generation system 100, the charge amount calculation unit 61 acquires the time from a clock (not shown), for example, at a predetermined period. Then, the usage amount of the grid AC power is obtained from the current sensor 5, the usage amount of the grid AC power at each time is plotted, and, for example, the power usage pattern PC from 24 hours before to the present is obtained. The charge amount calculation unit 61 obtains the corrected power usage pattern PC by, for example, averaging the power usage pattern PC stored in the storage unit 62 and the obtained power usage pattern PC. The charge amount calculation unit 61 stores the obtained power usage pattern PC in the storage unit 62.

  Further, the charge amount calculation unit 61 may correct the power generation pattern EG by acquiring information on the power generated by the solar cell 7 from the DC / DC converter 1, for example.

  For example, when the power generation pattern EG is corrected by the charge amount calculation unit 61 during the operation of the photovoltaic power generation system 100, the charge amount calculation unit 61 acquires the time from a clock (not shown) at a predetermined cycle, for example. Then, the electric power generated by the solar cell 7 is acquired from the DC / DC converter 1, the electric power generated at each time is plotted, and the electric power generation pattern EG by the solar cell 7 is obtained. The charge amount calculation unit 61 obtains a corrected power generation pattern EG by, for example, averaging the power generation pattern EG stored in the storage unit 62 and the obtained power generation pattern EG. The charge amount calculation unit 61 stores the obtained power generation pattern EG in the storage unit 62.

The charge / discharge control unit 63 controls charge / discharge of the secondary battery 8. For example, the charge / discharge control unit 63 monitors and controls the charge amount of the secondary battery 8 via the charge amount meter 3. For example, the charge / discharge control unit 63 obtains the target charge amount from the charge amount calculation unit 61 and, based on the target charge amount, in the middle of the night from the commercial power supply SP to the secondary battery 8 via the AC / DC converter 4. Each part is controlled so that the secondary battery 8 is charged via the DC / DC converter 1 from the solar battery 7 in the daytime. For example, the charging / discharging control unit 63 uses the charging amount indicated by the charging portion F in accordance with the charging pattern BC during the midnight power time period of the previous day so that the secondary battery 8 is fully charged or close to the state at time T. Each part is controlled so that the secondary battery 8 is charged.

  For example, the charge / discharge control unit 63 charges the rechargeable battery 8 via the charge meter 3 so that the charge amount per unit time is maintained corresponding to the charge pattern EG during the midnight power hours. The secondary battery 8 is charged via the AC / DC converter 4 from the commercial power supply SP.

  Alternatively, for example, the charge / discharge control unit 63 monitors the charge amount of the secondary battery 8 via the charge amount meter 3 during the midnight power time period until the charge amount indicated by the charging portion F is reached. When the secondary battery 8 is charged from the SP via the AC / DC converter 4 and the charge amount indicated by the charging portion F is reached, the operation of the AC / DC converter 4 is stopped or the AC / DC converter is switched from the commercial power supply SP. 4 to cut off the supply of system AC power to 4.

  Next, operation | movement of the solar energy power generation system 100 is demonstrated using FIG.

  When there is daytime solar radiation and the generated power is greater than the consumed power (depending on the load LD in the house), as shown in the overlapping portion C of the power usage pattern PC and the power generation pattern EG in FIG. The DC / DC converter 1 converts it into DC power of a predetermined level, and the DC / AC inverter 2 converts it into AC power and supplies it to the load LD. At this time, the direction of power is monitored by the current sensor 5, and the DC / AC inverter 2 is controlled so as not to flow backward (do not sell power) to the commercial power supply SP. Furthermore, since generated power> power consumption, surplus power that cannot be consumed by the load LD in the house is generated, and this surplus power (see surplus generated power portion B in FIG. 2) is generated by the charge / discharge control unit 63. The secondary battery 8 is charged. At this time, the AC / DC converter 4 is in a stopped state, for example.

  After time T, when there is no solar radiation and the power consumption of the residential load LD is increased, the discharge power from the secondary battery 8 is converted into AC power by the DC / AC inverter 2 and the residential load LD To supply. During this time, the DC / AC inverter 2 is controlled by the current sensor 5 so that it does not flow backward (do not sell power) to the commercial power supply SP.

  When the charge amount of the secondary battery 8 is equal to or less than a predetermined value (for example, 50% or less) as the secondary battery charge target value in the midnight power time zone, the AC / DC converter 4 is operated, and the AC / DC converter 4, the secondary battery 8 is charged from the commercial power supply SP. This charging is controlled by, for example, the charge / discharge control unit 63 of the control circuit 6. The charge / discharge control unit 63 has a target value of the secondary battery charge amount (midnight power charge) calculated by the charge amount calculation unit 61, and charges using the late-night power so that the target value is reached in the morning. I do. For example, if the target value is 50%, the secondary battery 8 is fully charged by 50% in the morning.

  For example, the target value is calculated by the charge amount calculation unit 61 such that the charge amount at time T is fully charged or close to it. At this time, as shown in FIG. 3, in the charge amount calculation unit 61, for example, an initial set value (fixed value) 611 is multiplied by a multiplier 612 so that the target value does not change suddenly under conditions such as weather. The consumption pattern coefficient (variation value) 614 to be changed may be gradually changed to the target value by the low-pass filter 615. For example, the low-pass filter 615 is desirably changed so as to converge to the target value at a cycle of about one month.

  Although the power consumption is different in each home, the target value of the secondary battery charge amount is determined by the initial setting value 611 and the consumption pattern coefficient value 614, and the daily pattern data is reduced to reduce the daytime power purchase. By gradually changing to a value that originally matches the load LD, it is possible to converge to an average value for each household.

  As described above, in the first embodiment, the charge amount calculation unit 61 calculates the target charge amount based on the predicted value of the daily power consumption, and the charge / discharge control unit 63 calculates the calculated target charge amount. In the middle of the night, the secondary battery 8 is charged from the commercial power supply SP via the AC / DC converter 4 at midnight, and the secondary battery 8 is charged from the solar battery 7 via the DC / DC converter 1 in the daytime. To control. As a result, the power supply is mainly supplied from the secondary battery 8 to the load LD in a time zone where the power consumption by the load LD is large (for example, in the evening time zone), so that the usage amount of the system AC power can be reduced. Since the secondary battery 8 is charged using the grid AC power in a time zone where the power usage is low (for example, a midnight power time zone), the grid AC power usage can be suppressed to a necessary limit. That is, the use of grid AC power can be leveled.

  Therefore, for example, it is possible to reduce the amount of grid AC power used in a time zone where there is no discount on electricity charges, and to limit the amount of grid AC power used in the discount hours of electricity charges to a necessary limit. You can save a lot.

  In the first embodiment, the storage unit 62 stores the power usage pattern PC by the load LD, and the charge amount calculation unit 61 applies the load LD to the load LD based on the power usage pattern PC stored in the storage unit 62. The target charge amount is calculated so that the supply amount of the grid AC power is smaller than the current supply amount of the grid AC power. Thereby, in addition to being able to level the use of the grid AC power, the usage amount of the grid AC power can be reduced, for example, with respect to the entire power usage pattern PC in one day, and further the power charge can be saved.

  In the first embodiment, for example, the current sensor 5 detects the usage amount of the system AC power, and the charge amount calculation unit 61 stores the power stored in the storage unit 62 according to the detection result by the current sensor 5. The usage pattern PC is corrected. Thereby, even when the state of the load LD changes, the use of the grid AC power can be leveled so as to adapt to it.

Embodiment 2. FIG.
Next, a solar cell system 100i according to the second embodiment will be described. Below, it demonstrates focusing on a different part from Embodiment 1. FIG.

  In the first embodiment, for example, the secondary battery 8 is charged in the midnight power period of the previous day so that the secondary battery 8 is fully charged or close to the state at time T shown in FIG.

  However, when it is cloudy or raining, the battery may not be fully charged at time T, and there may be a day when the secondary battery 8 cannot be used effectively.

  Therefore, in the second embodiment, in order to solve this problem, as shown in FIG. 4, the control circuit 6i has a communication function (external information acquisition unit 9i) with the external information source IS. The external information acquisition unit 9 i obtains the next day's weather forecast information before the midnight power time via the communication line CL such as the Internet, and supplies it to the charge amount calculation unit 61.

  And the charge amount calculation part 61 changes the target value of charge amount only on the next day according to the condition, for example. For example, if the forecast for the next day is rainy, the surplus generated power portion B during the daytime cannot be expected, so the target charge amount for the next day is changed to 100%, for example. Thereby, for example, the charge / discharge control unit 63 fully charges the secondary battery 8 with late-night power, and uses each part in the consumption parts C and D in the consumption time zone of the next day (see FIG. 2). Control.

  Thus, in the second embodiment, the charge amount calculation unit 61 calculates the target charge amount calculated based on the power usage pattern PC stored in the storage unit 62 on the next day acquired by the external information acquisition unit 9i. Correct based on weather forecast information. Thereby, even when the weather of the next day is expected to change, the use of the grid AC power can be leveled to adapt to it.

  As described above, the photovoltaic power generation system according to the present invention is useful for power generation using sunlight.

DESCRIPTION OF SYMBOLS 1 DC / DC converter 2 DC / AC inverter 3 Charge meter 4 AC / DC converter 5 Current sensor 6, 6i Control circuit 7 Solar cell 8 Secondary battery 9i External information acquisition part 11 Distributor 12 Combining / distributor 61 Charge amount Calculation unit 62 Storage unit 63 Charge / discharge control unit 100, 100i Solar power generation system 611 Initial setting value 612 Multiplier 614 Consumption pattern coefficient 615 Low-pass filter

Claims (4)

Solar cells,
A DC / DC converter that converts direct-current power generated by the solar cell into direct-current power of a predetermined level;
A DC / AC inverter for converting the converted DC power into AC power;
An AC / DC converter that converts system AC power from the system power source into DC power;
A secondary battery;
A charge / discharge control unit for controlling charge / discharge of the secondary battery;
A charge amount calculation unit for calculating a target charge amount to the secondary battery;
With
The charge amount calculation unit calculates the target charge amount based on an expected value of power consumption of a day,
The charge / discharge control unit charges the secondary battery from the system power supply via the AC / DC converter at midnight based on the calculated target charge amount, and from the solar battery to the DC in the daytime. A control to charge the secondary battery via a DC converter,
The target charge amount is determined based on an initial setting value and a consumption pattern coefficient,
The consumption pattern coefficient is changed by a low-pass filter so that the consumption pattern coefficient multiplied by the initial setting value becomes a value suitable for a load.
A solar power generation system characterized by that. A storage unit for storing a power usage pattern according to the load;
The charge amount calculation unit calculates the target charge amount based on the stored power usage pattern so that the supply amount of the system AC power to the load is smaller than the current supply amount of the system AC power. The photovoltaic power generation system according to claim 1, wherein the photovoltaic power generation system is calculated. It further comprises a sensor that detects the amount of grid AC power used,
The photovoltaic power generation system according to claim 2, wherein the charge amount calculation unit corrects the power usage pattern according to a detection result by the sensor. An external information acquisition unit that acquires weather forecast information for the next day is further provided.
4. The solar light according to claim 1, wherein the charge amount calculation unit corrects the calculated target charge amount based on the acquired weather forecast information for the next day. Power generation system.

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