JP6439165B2 - AC power supply output power control method and AC power supply - Google Patents

Description

  The present invention relates to an output power control method and an AC power supply apparatus for an AC power supply apparatus, and more particularly to an output power control method and an AC power supply apparatus for an AC power supply apparatus that can be connected to a commercial power supply.

  2. Description of the Related Art In recent years, an AC power supply device that can transmit renewable energy generated by using a solar battery panel, a windmill, or the like through a system wiring to which commercial power is supplied is widely used. The electric power to be sent is stored in the power storage device, and the power storage device stores the renewable energy and the fossil fuel energy (commercial power) in a mixed state. The power to be transmitted is preferably renewable energy. This is because it is not desirable from the viewpoint of the use of renewable energy to store commercial power and send it again. Therefore, for example, in an AC power supply device that combines a power source using renewable energy and a power storage device such as a storage battery in order to realize stable operation of a private power generation facility, AC power generated based on the power output from the power storage device It is required to prevent reverse power flow to the system wiring side. Thus, Patent Document 1 shows an example of an AC power supply device that combines a solar battery and a storage battery.

  In the power storage solar power generation system described in Patent Literature 1, the amount of received power supplied from the system wiring is monitored, and the power storage means prevents the amount of received power from falling below a predetermined level. The amount of power output from the power conversion means for extracting power is controlled.

Japanese Patent No. 4765162

  However, in the technique described in Patent Document 1, although the received power can be reduced, the power stored in the load circuit cannot be supplied by the power that can be supplied by renewable energy among the power consumed by the load circuit. It can only be compensated by the power. That is, the technique described in Patent Document 1 has a problem that the amount of renewable energy that cannot be transmitted is large. Other problems and novel features will become apparent from the description of the specification and the accompanying drawings.

  One aspect of an output power method of an AC power supply apparatus according to the present invention is an output power control method for an AC power supply apparatus that operates in conjunction with a commercial AC power supply that supplies a commercial AC signal to a system wiring, and includes a first DC voltage. The voltage of the discharge power supplied from the power storage unit is controlled while controlling the voltage of the first DC voltage signal so that the bus voltage of the DC bus wiring from which the signal is output approaches a preset bus voltage command value. The first DC power signal is converted and output, and the first DC power signal and the second DC power signal supplied from the renewable energy source are combined in the DC bus wiring and connected to the system wiring. An AC power signal that calculates an output power obtained by adding the discharge power and the power of the second DC power signal based on a difference between the load power consumed in the load circuit and the discharge power, and outputs the output power to the system wiring Power of There while controlling the power of the AC power signal so that the output power, converts the DC power transmitted through the DC bus line to the AC power signal.

  One aspect of the AC power supply apparatus according to the present invention is an AC power supply apparatus that operates in conjunction with a commercial AC power supply that supplies a commercial AC signal to a system wiring, and includes a DC bus wiring that outputs a first DC voltage signal. The first DC power signal is converted by converting the voltage of the discharge power supplied from the power storage unit while controlling the voltage of the first DC voltage signal so that the bus voltage approaches the preset bus voltage command value. A first DC voltage converter that outputs the first DC power signal, a DC bus wiring that combines the first DC power signal and a second DC power signal supplied from a renewable energy source, and a load connected to the system wiring Based on the difference between the load power consumed in the circuit and the discharge power, the output power obtained by adding the discharge power and the power of the second DC power signal is calculated, and the power of the AC power signal output to the system wiring Said A control unit that outputs an inverter power command value that specifies the power of the AC power signal so as to be a power, and the power of the AC power signal is controlled based on the inverter power command value through the DC bus wiring. An inverter that converts the transmitted DC power into the AC power signal.

  In the output power control method and the AC power supply apparatus according to the present invention, the magnitude of the discharge power component supplied from the power storage unit included in the AC power signal output from the inverter follows the power consumption of the load circuit. Change. Thereby, in the power supply device concerning this invention, the power consumption of a load circuit is satisfy | filled with the discharge power supplied from an electrical storage part, and most of the generated electric power supplied from a renewable energy source can be sent out.

  According to the present invention, only renewable energy can be delivered.

1 is a block diagram of an AC power supply device according to a first exemplary embodiment; 1 is a block diagram of a converter according to a first embodiment. 1 is a block diagram of an inverter and an inverter control unit according to a first embodiment. 3 is a timing chart for explaining the operation of the AC power supply device according to the first exemplary embodiment; FIG. 3 is a block diagram for explaining a comparative example of the AC power supply device according to the first exemplary embodiment; It is a timing chart explaining operation | movement of the alternating current power supply apparatus of a comparative example.

Embodiment 1
Embodiments of the present invention will be described below with reference to the drawings. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. Moreover, in each drawing, the same code | symbol is attached | subjected to the same element and duplication description is abbreviate | omitted as needed.

  FIG. 1 shows a block diagram of an AC power supply apparatus 10 according to the first exemplary embodiment. In FIG. 1, in order to more specifically describe the usage mode of the AC power supply device 10, a commercial AC power supply SPS that is a target for the AC power supply device 10 to be linked and a load circuit that is a power supply target of the AC power supply device 10 The AC power supply system 1 including the solar battery panel PV and the storage battery BAT, which are power sources for the AC power signal output from the PL and the AC power supply apparatus 10, is shown.

  Note that the solar cell panel PV is an aspect of a renewable energy source, and an electric power source such as a wind power generation device or a hydroelectric power generation device can be used in addition to the solar cell panel PV. In the following description, the power output from the solar cell panel PV is referred to as generated power Ppv. In addition, the storage battery BAT is an aspect of the power storage unit, and a power storage device such as a large-capacity capacitor or a flywheel can be used in addition to the storage battery. In the following description, the power output from the storage battery BAT is referred to as discharge power Pbat.

  As shown in FIG. 1, the AC power supply device 10 outputs an AC power signal to the system wiring to which the commercial AC signal is supplied from the commercial AC power supply SPS. A load circuit PL that is a power supply destination is connected to the system wiring. In the following description, a connection point between the system wiring and the load circuit is referred to as a load connection point. Also, the power of the AC power signal output from the AC power supply apparatus 10 to the system wiring is referred to as Pinv, the load power consumed by the load circuit PL is referred to as Ppl, and the reverse power flow that is reversely supplied to the commercial AC power supply SPS is referred to as Pr.

  As shown in FIG. 1, an AC power supply apparatus 10 includes a second DC voltage converter (for example, a DC / DC converter 11), a first DC voltage converter (for example, a DC / DC converter 12), and an inverter (for example, a DC). / AC inverter 13), a control unit (for example, inverter control unit 14), and a DC bus wiring 15.

  The DC / DC converter 11 converts the voltage of the generated power supplied from the solar cell panel PV and outputs a second DC power signal. In the following description, in order to simplify the description, the loss generated in the DC / DC converter 11 is omitted, and the generated power supplied from the solar cell panel PV and the power of the second DC power signal are the same. Think. The DC / DC converter 11 can be omitted depending on the specifications of the solar battery panel PV.

  The DC / DC converter 12 controls the voltage of the first DC voltage signal so that the bus voltage Vdc of the DC bus wiring 15 from which the first DC voltage signal is output approaches a preset bus voltage command value. However, the voltage of the discharge power supplied from the storage battery BAT is converted to output the first DC power signal. The bus voltage Vdc is controlled by the bus voltage control unit of the DC / DC converter 12. In the following description, in order to simplify the description, loss generated in the DC / DC converter 12 is omitted, and the discharge power supplied from the storage battery BAT and the power of the first DC power signal are considered to be the same.

  The second DC power signal output from the DC / DC converter 11 and the first DC power signal output from the DC / DC converter 12 are combined by the DC bus wiring 15 and supplied to the DC / AC inverter 13.

  The DC / AC inverter 13 converts the DC power transmitted through the DC bus wiring into an AC power signal while controlling the power of the AC power signal based on the inverter power command value output from the inverter control unit 14. The DC / AC inverter 13 outputs the generated AC power signal to the system wiring.

  The inverter control unit 14 is based on the difference between the load power Ppl consumed by the load circuit PL connected to the system wiring and the discharge power Pbat and the power of the discharge power Pbat and the second DC power signal (for example, generated power Ppv). Is output, and an inverter power command value that specifies the power of the AC power signal is output so that the power of the AC power signal output to the system wiring becomes the output power. Here, the discharge power Pbat is acquired by the discharge power monitoring unit CS_BAT. The load power is acquired by the load power monitor unit CS_PL. Here, the inverter control unit 14 controls the output capability of the DC / AC inverter 13 so that the amount of discharge power output from the storage battery BAT does not exceed the amount of load power.

  Here, details of the DC / DC converter 12 will be described. FIG. 2 is a block diagram of the DC / DC converter 12 according to the first embodiment. As shown in FIG. 2, the DC / DC converter 12 includes a bus voltage control unit 20, a PWM control unit 21, and a converter unit 22.

  The bus voltage control unit 20 acquires the bus voltage Vdc of the DC bus wiring 15 and instructs to increase or decrease the power of the first DC voltage signal based on the difference value between the bus voltage Vdc and a preset bus voltage command value. The discharge power command value to be output is output. This discharge power command value is output to the PWM control unit 21.

  The PWM control unit 21 determines the duty ratio of the PWM signal based on the discharge power command value and outputs the PWM signal to the converter unit 22. Thereby, the DC / DC converter 12 controls the power of the first DC voltage signal so that the bus voltage Vdc is maintained near the bus voltage command value.

  Next, details of the DC / AC inverter 13 and the inverter control unit 14 will be described. FIG. 3 is a block diagram of the DC / AC inverter 13 and the inverter control unit 14 according to the first embodiment.

  As shown in FIG. 3, the inverter control unit 14 includes a load power detection unit 30, a discharge power detection unit 31, an error detector 32, and an error amplifier 33. The DC / AC inverter 13 includes an inverter power control unit 36, a system phase detection unit 35, an inverter power control unit 36, a PWM control unit 37, and an inverter unit 38.

  The load power detection unit 30 detects the magnitude of the load power consumed by the load circuit PL based on the load power information obtained from the load power monitor unit CS_PL. For example, the load power information includes system voltage information and load current information. Then, the load power detection unit 30 calculates the load power Ppl by multiplying the system voltage and the load current. Note that the load power Ppl output by the load power detection unit 30 may be multiplied by a coefficient considering an error in the system.

  The electric power detector 31 calculates the discharge power Pbat output from the DC / DC converter 12 based on the discharge power information obtained from the discharge power monitor CS_BAT. For example, the discharge power information includes a storage unit output voltage that is information on a voltage output from the storage battery BAT and a storage unit output current that is information on a current output from the storage battery BAT. Then, the discharge power detection unit 31 calculates the discharge power Pbat by multiplying the storage unit output voltage and the storage unit output current. Note that the discharge power Pbat output from the discharge power detection unit 31 may be multiplied by a coefficient that takes into account the loss or the like in the DC / DC converter 12. Details of the operation of the discharge output detector 31 will be described later.

  The error detector 32 calculates the difference between the load power Ppl calculated by the load power detection unit 30 and the discharge power Pbat calculated by the discharge power detection unit 31. The error amplifier 33 amplifies the difference value calculated by the error detector 32. The error amplifier 33 may be one that multiplies the difference value calculated by the error detector 32 by a fixed numerical value, or one that integrates the difference value with respect to time. In the present embodiment, the difference value output from the error detector 32 is an amplification factor A that is sufficiently large with respect to the discharge power Pbat (for example, a value that is two or more digits larger than the maximum value of the discharge power Pbat, Ideally ∞) is realized by applying the error amplifier 33. The value output from the error amplifier 33 becomes the inverter power command value Pinv * to the DC / AC inverter 13.

  The system phase detection unit 35 acquires system voltage information from the system signal monitor unit (not shown in FIG. 1), and detects the phase of the commercial AC signal on the system wiring based on the system voltage information. Then, the system phase detection unit 30 outputs the detected phase information of the commercial AC signal to the inverter power control unit 36.

  The inverter power control unit 36 acquires the inverter current and the inverter power measurement value by the output current monitor unit that monitors the output power of the own inverter (not shown in FIG. 1). The inverter power control unit 36 determines whether to increase or decrease the inverter output power based on the inverter power command value Pinv *, and outputs an inverter control signal based on the determination. The inverter power control unit 36 adjusts the value of the inverter control signal based on the phase information output from the system phase detection unit 35 so that the phase of the AC power signal output from the inverter unit 38 matches the phase of the commercial AC signal. To do. Then, the PWM control unit 37 determines the duty ratio of the PWM signal based on the inverter control signal, and outputs the PWM signal to the inverter unit 38. The power Pinv of the AC power signal output from the DC / AC inverter 13 is a value obtained by adding the load power Ppl and the generated power Ppv by performing the above control.

  The inverter power control unit 36 may generate an inverter control signal based on the inverter power command value Pinv * without using the inverter power measurement value.

  Next, the operation of the AC power supply device 10 according to the first exemplary embodiment will be described. First, the relationship between the power Pinv of the AC power signal output from the AC power supply apparatus 10 and the power Pr flowing backward to the system power supply SPS side will be described.

First, in the AC power supply device 10 according to the first exemplary embodiment, when the conversion efficiencies of the DC / DC converters 11 and 12 and the DC / AC inverter 13 are 100%, the relations of the expressions (1) to (4) are established.
Ppv + Pbat = Pinv (1)
Pinv = Pr + Ppl (2)
Pinv = Pinv * (3)
Pinv * = A (Ppl−Pbat) (4)

And the relationship of (5) Formula can be derived from (1) Formula and (2) Formula.
Ppv + Pbat = Pr + Ppl (5)
Further, the relationship of equation (6) can be derived from equations (3) and (4).
Pinv = A (Ppl−Pbat) (6)
And the relationship of Formula (7) can be derived from Formula (1), Formula (5), and Formula (6).
Pr = Ppv− (Pinv / A) = Ppv (1-1 / A) − (Pbat / A) (7)
Here, when the amplification factor A is set to a value sufficiently larger than the maximum value of the discharge power Pbat (ideally ∞), the reverse flow power Pr becomes equal to the generated power Ppv. Further, it can be seen from the equation (7) that the reverse flow power Pr follows the generated power Ppv but does not exceed the generated power Ppv. That is, by using the AC power supply device 10 according to the first embodiment, the generated power Ppv or the reverse flow power Pr less than or equal to the generated power Ppv can be sent to the commercial AC power supply SPS. This operation will be described using a timing chart. FIG. 4 is a timing chart showing the operation of the AC power supply apparatus 10 according to the first embodiment.

  In the example illustrated in FIG. 4, the load power Ppl and the generated power Ppv change with time. As illustrated in FIG. 4, the AC power supply device 10 according to the first embodiment changes the magnitude of the discharge power Pbat by following the change in the load power Ppl. Therefore, in the AC power supply device 10, almost all of the generated power Ppv is output to the commercial AC power supply SPS side as the reverse power flow Pr. Further, as shown in FIG. 4, in the AC power supply device 10, even when the generated power Ppv becomes zero, the magnitude of the discharge power Pbat is made to follow the change in the load power Ppl before that, so the discharge power Pbat is It is consumed by the load circuit PL without flowing back into the commercial AC power supply SPS.

  In order to further describe the operation of the AC power supply device 10 described above, the operation of the AC power supply device 101 as a comparative example will be described in comparison with the operation of the AC power supply device 10. FIG. 5 shows a block diagram of an AC power supply system 100 that is a comparative example of the AC power supply system 1 according to the first embodiment.

  As shown in FIG. 5, an AC power supply system 100 according to a comparative example is obtained by replacing the AC power supply device 10 of the AC power supply system 1 shown in FIG. 1 with an AC power supply device 101. In this AC power supply device 101, the DC / DC converter 12, the DC / AC inverter 13, and the inverter control unit 14 of the AC power supply device 10 are replaced with a DC / DC converter 112, a DC / AC inverter 113, and a converter control unit 114. It is a thing.

  In AC power supply apparatus 101, DC / DC out of the power (for example, output power Pinv) of the AC power signal output from DC / AC inverter 113 is such that reverse power flow Pr is reduced as much as possible by converter control unit 114. The power that cannot be covered by the generated power Ppv output from the converter 11 is supplemented by the discharge power Pbat output from the storage battery BAT. In this AC power supply device 101, the bus voltage Vdc is maintained by the DC / AC inverter 113.

  Next, the operation of the AC power supply apparatus 101 according to the comparative example shown in FIG. 5 will be described. FIG. 6 is a timing chart for explaining the operation of the AC power supply apparatus 101 according to the comparative example. As shown in FIG. 6, in the AC power supply system 100, the AC power supply apparatus 101 suppresses the output of the discharge power Pbat in a period where the load power Ppl is smaller than the generated power Ppv (for example, the periods TM1 and TM3). Power corresponding to the power Ppv is output as an AC power signal. Then, AC power supply system 100 causes surplus power that cannot be consumed by load circuit PL to flow backward to commercial AC power supply SPS.

  Further, in the AC power supply system 100, in a period in which the generated power Ppv is lower than the load power Ppl (for example, periods TM2 and TM4), the discharge power Pbat output from the storage battery BAT is insufficient power obtained by subtracting the generated power Ppv from the load power Ppl. Make up with. During this period, there is no power to be reversely flowed to the commercial AC power supply SPS side, so the reverse flow power Pr becomes zero.

  On the other hand, in the AC power supply device 10 according to the first embodiment, since the increase / decrease in the discharge power Pbat is caused to follow the increase / decrease in the load power Ppl, the generated power Ppv is used even when the generated power Ppv is smaller than the load power Ppl. It is possible to reversely flow the wiring.

  From the above description, according to the AC power supply apparatus 10 according to the first embodiment, most of the generated power Ppv supplied from the renewable energy source can be sent to the commercial AC power supply SPS side.

  Therefore, by using the AC power supply device 10 according to the first embodiment, it is possible to effectively use renewable energy. For example, in the AC power supply apparatus 101 according to the comparative example, part of the power that can be sent to the commercial AC power supply SPS side is consumed by the load circuit, and the effective use of renewable energy is limited. On the other hand, by using the AC power supply device 101 according to the first embodiment, for example, surplus power accumulated at night is supplied in the daytime, and all the renewable energy is sent to the system, thereby effectively using the renewable energy. Is more possible.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 AC power supply system 10 AC power supply device 11, 12 DC / DC converter 13 DC / AC inverter 14 Inverter control part 15 DC bus wiring 20 Bus voltage control part 21 PWM control part 22 Converter part 30 Load power detection part 31 Discharge power detection part 32 Error detector 33 Error amplifier 34 Adder 35 System phase detector 36 Inverter power controller 37 PWM controller 38 Inverter CS_PL Load power monitor CS_BAT Discharge power monitor SPS Commercial AC power supply

Claims (10)

An output power control method for an AC power supply device that operates in conjunction with a commercial AC power supply that supplies a commercial AC signal to the system wiring,
Supplied from the power storage unit while controlling the voltage of the first DC voltage signal so that the bus voltage of the DC bus wiring from which the first DC voltage signal is output approaches the preset bus voltage command value. Converting the voltage of the discharge power and outputting the first DC power signal,
Combining the first DC power signal and the second DC power signal supplied from the renewable energy source in a DC bus wiring;
An output power obtained by adding the discharge power and the power of the second DC power signal based on a difference between the load power consumed by the load circuit connected to the system wiring and the discharge power is calculated, and the system wiring An AC power supply device that converts the DC power transmitted through the DC bus wiring into the AC power signal while controlling the power of the AC power signal so that the power of the AC power signal output to the output power becomes the output power. Output power control method.   2. The output power control method for an AC power supply apparatus according to claim 1, wherein the electric energy of the discharge electric power is equal to or smaller than the electric energy of the load electric power.   The power amount of the AC power signal is specified by an inverter power command value calculated based on a value obtained by multiplying a difference value between the load power and the discharge power by a value sufficiently larger than the discharge power. Or the output power control method of the alternating current power supply device of 2.   4. The AC power supply apparatus according to claim 3, wherein it is determined whether to increase or decrease the latest inverter power measurement value based on the inverter power command value, and the power of the AC power signal is controlled based on the determination. Output power control method.   4. The output power control method for an AC power supply apparatus according to claim 1, wherein the second DC power signal is output by converting a voltage of generated power supplied from the renewable energy source. 5. An AC power supply device that operates in conjunction with a commercial AC power supply that supplies a commercial AC signal to the system wiring,
Supplied from the power storage unit while controlling the voltage of the first DC voltage signal so that the bus voltage of the DC bus wiring from which the first DC voltage signal is output approaches the preset bus voltage command value. A first DC voltage converter that converts the voltage of the discharge power and outputs a first DC power signal;
A DC bus wiring for combining the first DC power signal with a second DC power signal supplied from a renewable energy source;
An output power obtained by adding the discharge power and the power of the second DC power signal based on a difference between the load power consumed by the load circuit connected to the system wiring and the discharge power is calculated, and the system wiring A controller that outputs an inverter power command value that specifies the power of the AC power signal so that the power of the AC power signal to be output becomes the output power;
An inverter that converts the DC power transmitted through the DC bus wiring into the AC power signal while controlling the power of the AC power signal based on the inverter power command value;
AC power supply apparatus having   The AC power supply apparatus according to claim 6, wherein the control unit outputs the inverter power command value so that an amount of electric power of the discharge power is equal to or less than an amount of electric power of the load power.   The inverter determines, based on the inverter power command value, whether to increase or decrease the inverter power measurement value acquired by the output current monitor unit that monitors the output power of the own inverter. The alternating current power supply device according to claim 6 which controls electric power of said exchange power signal.   The alternating current according to any one of claims 6 to 8, further comprising a second DC voltage converter that converts a voltage of the generated power supplied from the renewable energy source and outputs the second DC power signal. Power supply.   10. The AC power supply apparatus according to claim 6, further comprising: a load power monitor unit that monitors the load power; and a discharge power monitor unit that monitors the discharge power.

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