JP2014230366A - Power generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generation device capable of maintaining a voltage of a DC bus for independent operation during a power failure by surely preventing power that should not be returned to a system, from flowing out to the system when performing solar cell power generation and battery discharge.SOLUTION: A power generation device comprises: a battery which is connected to a DC bus and maintains a DC bus voltage constant; a solar cell; a DC/DC converter which converts output of the solar cell and is connected to the DC bus; a bidirectional AC/DC converter which is connected between the DC bus and a system and converts DC power and AC power; an AC measuring part for measuring AC load power of an AC load connected to the system; and an arithmetic part for calculating control power of the AC/DC converter. The arithmetic part controls AC output power of the AC/DC converter equal to or less than (solar cell power+AC measurement power) and causes the solar cell power to flow inversely to the system.

Description

  The present invention relates to a household power generator having a solar cell and a battery.

  There is a growing need for a power generation device that combines photovoltaic power generation and a battery to return the amount of photovoltaic power generation to the system during grid connection and to be an independent power source during a power failure. When solar power generation and battery discharge are performed, it is necessary to prevent power that does not need to be returned to the system, such as battery discharge power, from flowing into the system.

Japanese Patent No. 4765162

  As a conventional power generator, for example, power received from a system is detected to control a bidirectional chopper (DC / DC converter) of the battery. In the case of such a configuration, there is a problem that if the power generated by the solar power is small and the battery is not discharged, the DC bus voltage (inverter input DC voltage) is lowered and it becomes difficult to operate independently.

  The embodiments have been made to solve the above-described problems, and when performing solar cell power generation and battery discharge, it is possible to reliably prevent power that does not need to be returned to the system from flowing into the system, and to be independent during power outages. An object of the present invention is to provide a power generator capable of maintaining the voltage of a DC bus for operation.

  A power generator according to an embodiment includes a battery connected to a DC bus and maintaining a DC bus voltage constant, a solar cell, a DC / DC converter that converts the output of the solar cell and is connected to the DC bus, A bidirectional AC / DC converter connected between the DC bus and the system for converting DC power and AC power; an AC measuring unit for measuring AC load power of an AC load connected to the system; And an arithmetic unit that calculates the control power of the AC / DC converter. The arithmetic unit controls the AC output power of the AC / DC converter to be equal to or less than (solar cell power + AC measured power), and reversely flows the solar cell power to the system.

It is a lineblock diagram of the power generator concerning a 1st embodiment. It is another Example of the electric power generating apparatus which concerns on 1st Embodiment, and is a block diagram of the electric power generating apparatus provided with DC / DC5 for batteries. It is a block diagram which shows the time of the independent operation of the electric power generating apparatus shown in FIG. It is a block diagram which shows the time of the independent operation of the electric power generating apparatus shown in FIG. It is a block diagram of the electric power generating apparatus which concerns on 2nd Embodiment. It is a block diagram which shows the time of the independent operation of the electric power generating apparatus shown in FIG. It is a block diagram of the electric power generating apparatus which concerns on 3rd Embodiment. It is a block diagram which shows the time of the independent operation of the electric power generating apparatus shown in FIG.

  Hereinafter, a power generator according to an embodiment will be described with reference to the drawings.

[First Embodiment]
(Constitution)
1 and 2 are configuration diagrams of the power generation device according to the first embodiment.

  The power generator according to the first embodiment includes a battery 4 connected to a DC bus, a solar cell (hereinafter referred to as PV) 2, and a PV DC / DC converter (hereinafter referred to as PV) that converts the output of PV and supplies it to the DC bus. 3) and a bidirectional AC / DC converter (hereinafter referred to as bidirectional AC / DC) that is connected between the DC bus and the system 8 and converts DC power / AC power. 1, an AC measurement unit 7 that measures the AC load power of an AC load 9 such as a home appliance connected to the system 8, and a calculation unit 6 that calculates the control power (AC output power) of the AC / DC 1. . When the DC bus voltage and the battery voltage are different, as shown in FIG. 2, a battery bidirectional DC / DC converter (hereinafter referred to as a battery bidirectional DC / DC) 5 is used, and the battery 4 is replaced with a DC bus. Connected.

(Function)
The calculation unit 6 controls the bidirectional AC / DC1 output power based on the AC measured power and the PV power. The bidirectional AC / DC 1 performs AC power control according to a command from the calculation unit 6. The DC DC / DC 3 for PV performs MPPT (Maximum Power Point Tracking) control and is, for example, a boost chopper. The system voltage is AC100V or AC200V. A bidirectional DC / DC 5 for battery in FIG. 2 is a step-up / step-down chopper, and performs control (DC bus constant voltage control) for keeping the DC bus voltage constant. The DC bus voltage is, for example, about DC 360V ± 10%. Accordingly, the battery bidirectional DC / DC 5 charges (eg, steps down) the battery 4 when the DC bus voltage exceeds a predetermined value, and discharges (eg, steps up) the battery 4 when the DC bus voltage decreases. Note that when the DC bus voltage and the battery voltage match and the battery 4 is directly connected to the DC bus as shown in FIG. 1, the battery 4 maintains the DC bus at a constant voltage without performing any special control. To charge or discharge.

First, when all the PV power is contracted to be sold between the user and the power company, that is, in the case of the control to reversely flow the PV power to the system with the push-up due to the battery discharge, the arithmetic unit 6 controls the AC / DC 1. The power, that is, the AC output power is controlled to be equal to or less than (PV power + AC measured power). As a result, the reverse power flow is
Reverse power flow ≦ (PV power + AC measured power) −AC load power = PV power (1)
Thus, it is possible to prevent power that does not need to be returned to the grid (battery discharge power that is not allowed to flow back to the grid or fuel cell power that will be described later) from flowing into the grid. Note that the above-described control for causing the PV power to reversely flow to the system with the push-up due to battery discharge refers to control for causing all the PV power to reversely flow to the system while discharging the battery.

Next, between the user and the power company, when the surplus amount obtained by subtracting the amount consumed in the home from the PV power is set as a power sale contract, that is, when the control is performed to reversely flow the PV power to the system without boosting due to battery discharge. The calculation unit 6 controls the AC output power of the AC / DC 1 to be equal to or lower than the PV power. As a result, the reverse power flow is
Reverse power flow ≤ PV power-AC load power (2)
Thus, power that does not need to be returned to the grid is prevented from flowing into the grid. Note that the above-described control for reverse power flow of PV power to the system without boosting due to battery discharge means reverse power flow to the system by subtracting the load power (load power) from the PV power without discharging the battery. Indicates the control to be performed. At this time, since the DC bus voltage rises to a predetermined voltage (for example, 360 V) or more, the battery 4 (battery bidirectional DC / DC5) does not discharge. When the AC output power (PV power) of the AC / DC 1 is smaller than the AC load power, the shortage is supplied from the system 9 to the AC load 9.

Furthermore, when there is no power sale contract between the user and the power company, that is, when control is performed so as not to flow backward to the grid, the arithmetic unit 6 controls the AC output power of the AC / DC 1 to be equal to or less than the AC measured power. As a result, the reverse power flow is
Reverse power flow ≦ AC measurement power−AC load power = 0 (3)
Thus, power that does not need to be returned to the grid is prevented from flowing into the grid. At this time, when (PV power-AC load power) is positive, the battery 4 is charged with this (PV power-AC load power).

  Next, FIG. 3 and FIG. 4 show operations when the system is blacked out and the PV power is small.

In FIG. 3, since the battery 4 is directly connected to the DC bus, the DC bus voltage is maintained. In FIG. 4, since the battery DC / DC 5 performs DC bus constant voltage control, the DC bus voltage is maintained. When the control unit 1a of the AC / DC1 detects a system power failure (decrease in the system voltage), the AC / DC1 is controlled from the power control that outputs AC power in accordance with the phase of the system voltage so far, for example, AC100V. The AC / DC 1 switches to constant AC voltage output that it outputs. The AC output power at this time is
AC output power = AC load power = PV power + battery discharge power (4)
It becomes. When the PV power exceeds the AC load power, the surplus is charged to the battery.

  Thereby, it becomes possible to perform a self-sustained operation without losing the DC bus voltage at the time of a power failure and stopping the apparatus.

(effect)
Electric power that does not need to be returned to the grid is prevented from flowing to the grid, and in the event of a power failure, the voltage of the DC bus is maintained by the battery, and the AC power required for the AC load can be supplied.

[Second Embodiment]
(Constitution)
FIG. 5 is a configuration diagram of the second embodiment.

  The power generation device according to the second embodiment converts the output of the battery 4, the battery bidirectional DC / DC 5 that controls charging / discharging of the battery 4 and is connected to the DC bus, and outputs the PV 2 and PV to the DC bus. DC / DC3, bidirectional AC / DC1 connected between the DC bus and the system and converting DC power / AC power, and AC output fuel cell (hereinafter referred to as FC) connected to the AC line 10 and an electric vehicle charger (hereinafter referred to as an EV charger) 11, an AC measurement unit 7 that measures (AC load power + EV charger power), and a calculation unit 6 that calculates control power. When the DC bus voltage and the battery voltage are the same, the battery bidirectional DC / DC 5 is not necessary.

(Function)
The bidirectional AC / DC 1 performs AC power control according to a command from the arithmetic unit 6, the PV DC / DC 3 performs MPPT control, and the battery bidirectional DC / DC 5 performs DC bus constant voltage control. The FC 10 is controlled by the calculation unit 6 and notifies the calculation unit 6 of the FC power.

First, when all the PV power is contracted to be sold between the user and the power company, that is, when control is performed to reversely flow the PV power to the system with battery discharge and FC power generation, The AC output power of DC1 is controlled to (PV power + AC measurement power-FC power) or less. As a result, the reverse power flow is
Reverse power flow ≦ (PV power + AC measured power−FC power) + FC power−AC load power−EV charger power = PV power (5)
Thus, power that does not need to be returned to the grid is prevented from flowing into the grid.

Next, between the user and the power company, if the surplus amount obtained by subtracting the in-house consumption from the PV power is set as a power sale contract, that is, the PV power is reversely flowed to the system without battery discharge and FC power generation. At the time of control, the arithmetic unit 6 controls the AC output power of the AC / DC 1 to (PV power-FC power) or less. As a result, the reverse power flow is
Reverse power flow ≦ (PV power−FC power) + FC power−AC load−EV charger power = PV power−AC load−EV charger power (6)
Thus, power that does not need to be returned to the grid is prevented from flowing into the grid. That is, the surplus obtained by subtracting the AC measured power (EV charger power + AC load power) from the PV power is reversely flowed into the system (PV power is reversely flowed without being pushed up). At this time, the FC power is charged in the battery. That is, FC power flows out to the grid side, but the PV power is charged to the battery 4 through the DC bus accordingly. Alternatively, in this case, the FC may be stopped and the AC output power of the AC / DC 1 may be controlled below the PV power.

Furthermore, when the user and the electric power company do not have a power sale contract, the control unit 6 calculates the AC output power of the AC / DC 1 as (AC measured power−FC power). Control to: As a result, the reverse power flow is
Reverse power flow ≦ (AC measurement power−FC power) + FC power−AC load−EV charger power = 0 (7)
Thus, power that does not need to be returned to the grid is prevented from flowing into the grid. At this time, when (FC power + PV power−AC load−EV charger power) is positive, the positive power is charged in the battery. When the FC power is larger than (AC load + EV charger power), the AC / DC 1 is instructed by the arithmetic unit 6 to perform AC / DC conversion, and the battery 4 is charged with a larger amount of power.

  Next, FIG. 6 shows the operation when the system fails and the PV power is small.

Since the battery 4 is directly connected to the DC bus, or the battery DC / DC 5 performs DC bus constant voltage control, the DC bus voltage is maintained. The control unit 1a of the AC / DC 1 detects a power failure of the system, and switches the control of the AC / DC 1 from the power control that outputs AC power according to the phase of the system voltage so far to the AC voltage constant control. The AC output power at this time is
AC output power = AC load power + EV charger power−FC power = PV power + battery discharge power (8)
It becomes. When PV power + FC power exceeds AC load power + EV charger power, the battery 4 is charged with surplus.

  Thereby, it becomes possible to perform a self-sustained operation without losing the DC bus voltage at the time of a power failure and stopping the apparatus.

(effect)
When FC and EV chargers are AC-connected, power that does not need to be returned to the grid is prevented from flowing into the grid, and the DC bus voltage is maintained by the battery in the event of a power failure, and AC power required for the AC load is maintained. Supply is possible.

[Third Embodiment]
(Constitution)
FIG. 7 is a configuration diagram of the third embodiment.

  The power generation device according to the third embodiment converts the output of the battery 4, the battery bidirectional DC / DC 5 that controls charging / discharging of the battery 4, and is connected to the DC bus, and outputs the PV 2 and PV to the DC bus. Connected to DC / DC3, DC bus and system, bidirectional AC / DC1 for converting DC power / AC power, AC measuring unit 7 for measuring AC load power, and DC bus DC load 12, DC output FC 13 and EV charger 14, DC measurement unit 15 that measures (DC load power + EV charger power), and control power (AC output power) of bidirectional AC / DC 1 are calculated. It is comprised from the calculating part 6. When the DC bus voltage and the battery voltage are the same, the battery bidirectional DC / DC 5 is not necessary.

(Function)
The bidirectional AC / DC 1 performs AC power control in accordance with a command from the arithmetic unit 6, the PV DC / DC 3 performs MPPT control, and the battery bidirectional DC / DC 5 performs DC bus constant voltage control. The FC 13 is controlled by the calculation unit 6 and notifies the calculation unit 6 of the generated power.

First, when all the PV power is contracted to be sold between the user and the power company, that is, when the control is performed to reversely flow the PV power to the system with battery discharge and FC power generation, the AC of AC / DC1 The output power is controlled to (PV power + AC measured power) or less. As a result, the reverse power flow is
Reverse power flow ≦ (PV power + AC measured power) −AC load power = PV power (9)
Thus, power that does not need to be returned to the grid is prevented from flowing into the grid.

Next, in the case where the surplus amount obtained by subtracting the residential consumption from the PV power is set as a power sale contract between the user and the electric power company, that is, control to reversely flow the PV power to the system without battery discharge and FC power generation. In this case, the AC output power of the AC / DC 1 is controlled to be equal to or less than (PV power-DC measured power). As a result, the reverse power flow is
Reverse power flow ≦ (PV power−DC measured power) −AC load power = PV power−AC load power−DC load power−EV charger power (10)
Thus, power that does not need to be returned to the grid is prevented from flowing into the grid. At this time, the FC power is charged in the battery 4.

Further, when there is no power sale contract between the user and the electric power company, that is, when control is performed so as not to flow backward to the grid, the AC output power of the AC / DC 1 is controlled to be equal to or less than the AC measured power. As a result, the reverse power flow is
Reverse power flow ≦ AC measurement power−AC load power = 0 (11)
Thus, power that does not need to be returned to the grid is prevented from flowing into the grid. At this time, when (FC power + PV power−AC load power−DC load power−EV charger power) is positive, the positive power is charged in the battery 4.

  Next, FIG. 8 shows the operation when the system fails and the PV power is small.

Since the battery 4 is directly connected to the DC bus, or the battery DC / DC 5 performs DC bus constant voltage control, the DC bus voltage is maintained. The control unit 1a of the AC / DC 1 detects a power failure of the system, and switches the control of the AC / DC 1 from power control that outputs AC power according to the phase of the system voltage so far to constant AC voltage control. The AC output power at this time is
AC output power = AC load power = PV power + FC power + battery discharge power−EV charger power−DC load power (12)
It becomes. When PV power + FC power exceeds DC load power + EV charger power, the battery 4 is charged with surplus.

  Thereby, it becomes possible to perform a self-sustained operation without losing the DC bus voltage at the time of a power failure and stopping the apparatus.

(effect)
When FC and EV chargers are connected to DC, power that does not need to be returned to the grid is prevented from flowing into the grid, and the DC bus voltage is maintained by the battery in the event of a power failure, and AC power required for the AC load is maintained. Supply is possible.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Bidirectional AC / DC, 2 ... Solar cell, 3 ... DC / DC for solar cells, 4 ... Battery, 5 ... Bidirectional DC / DC for batteries, 6 ... Operation part, 7 ... AC measurement part, 8 ... System , 9 ... AC load, 10 ... AC output fuel cell, 11 ... AC connection EV charger, 12 ... DC load, 13 ... DC output fuel cell, 14 ... DC connection EV charger.

Claims (15)

A battery connected to the DC bus to maintain a constant DC bus voltage;
Solar cells,
A DC / DC converter that converts the output of the solar cell and is connected to the DC bus;
A bi-directional AC / DC converter connected between the DC bus and the system for converting DC power and AC power;
An AC measuring unit for measuring AC load power of an AC load connected to the system;
A calculation unit for calculating the control power of the AC / DC converter,
The calculation unit controls the AC output power of the AC / DC converter to be equal to or less than (solar cell power + AC measured power), and reversely flows the solar cell power to the system.   The calculation unit controls the AC output power of the AC / DC converter to be equal to or lower than solar cell power, and reversely flows a surplus obtained by subtracting the AC load power from the solar cell power to the system. The power generator described.   The power generation device according to claim 1, wherein the arithmetic unit controls the AC output power of the AC / DC converter to be equal to or less than the AC measured power, and does not reversely flow the solar cell power to the system.   An AC output fuel cell connected to an AC line connected to the system is further provided, and the calculation unit has an AC output power of the AC / DC converter equal to or less than (solar cell power + AC measurement power−fuel cell power). The power generator according to claim 1, wherein the solar cell power is reversely flowed to the grid. An electric vehicle charger connected to an AC line connected to the system;
The AC measurement unit measures (AC load power + electric vehicle charger power consumption), and the calculation unit controls the AC output power of the AC / DC converter to (solar cell power + AC measurement power) or less, The power generation device according to claim 1, wherein the solar cell power is reversely flowed to the grid.   An AC output fuel cell connected to an AC line connected to the system and an electric vehicle charger are further provided, and the AC measurement unit measures (AC load power + electric vehicle charger power consumption), and the arithmetic unit 2. The power generation device according to claim 1, wherein the AC output power of the AC / DC converter is controlled to be equal to or less than (solar cell power + AC measurement power−fuel cell power), and the solar cell power flows backward to the grid. .   The arithmetic unit controls the AC output power of the AC / DC converter to (solar cell power-fuel cell power) or less, or stops the fuel cell, and converts the AC output power of the AC / DC converter to a solar cell. The power generator according to claim 4 or 6, wherein the power is controlled to be equal to or lower than electric power, and a surplus obtained by subtracting AC measured power from the solar battery power is reversely flowed to the system.   The said calculating part controls AC output electric power of the said AC / DC converter below (AC measurement electric power-fuel cell electric power), and does not reversely flow the said solar cell electric power to the said system | strain of Claim 4 or 6 Power generation device. A DC output fuel cell connected to the DC bus; and a DC measuring unit for measuring DC load power of a DC load connected to the DC bus;
The power generation device according to claim 1, wherein the arithmetic unit controls the AC output power of the AC / DC converter to be equal to or less than (solar cell power + AC measured power) and reversely flows the solar cell power to the system. A DC load is connected to the DC bus,
An electric vehicle charger connected to the DC bus; and a DC measurement unit for measuring (DC load power + electric vehicle charger power),
The power generation device according to claim 1, wherein the arithmetic unit controls the AC output power of the AC / DC converter to be equal to or less than (solar cell power + AC measured power) and reversely flows the solar cell power to the system. A DC load is connected to the DC bus,
A DC output fuel cell and an electric vehicle charger connected to the DC bus; and a DC measuring unit for measuring (DC load power + electric vehicle charger power),
The power generation device according to claim 1, wherein the arithmetic unit controls the AC output power of the AC / DC converter to be equal to or less than (solar cell power + AC measured power) and reversely flows the solar cell power to the system.   The arithmetic unit controls the AC output power of the AC / DC converter to be equal to or less than (solar cell power-DC measured power), and the surplus obtained by subtracting the AC measured power and the DC measured power from the solar cell power is supplied to the system. The power generation device according to any one of claims 9 to 11, wherein the power generation device performs reverse power flow.   The power generation device according to any one of claims 9 to 12, wherein the arithmetic unit controls an AC output power of the AC / DC converter to be equal to or less than an AC measurement power and does not reversely flow into the system.   The power generator according to any one of claims 1 to 13, wherein the battery is connected to a DC bus by a DC / DC converter that bidirectionally converts battery output.   15. The AC / DC converter includes a control unit that detects a power failure in the system and switches the control of the AC / DC converter from power control to AC voltage constant control. The power generator according to item.

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