JP2013031308A - Power conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conditioner that reduces an inrush current when supplying power from an electric power system to a DC link section.SOLUTION: The power conditioner having a converter 4 for boosting a generated power of a solar panel 1 and an inverter 5 for converting power boosted by the converter 4 to AC power connectable to a system power supply 2 and having a DC link section 6 connecting them includes system power supply means 10 capable enabling power supply from the system power supply 2 to the DC link section 6 as bypassing the inverter 5. A control configuration is provided so that, when the power supply to the DC link section 6 is started through the system power supply means 10, the converter 4 is operated beforehand to boost a voltage at the DC link section 6 at least to a voltage of the electric power system supplied to the DC link section.

Description

  The present invention relates to a power conditioner, and more particularly to a power conditioner configured to be able to supply power from both a power generation unit side and a power system side to a DC link unit of an inverter.

  Conventionally, a power conditioner has been proposed as an inverter device for connecting DC power generated by a power generation unit such as a solar panel to a power system such as a commercial power source.

  FIG. 3 shows an example of such a power conditioner. The power conditioner shown in this figure is a power conditioner of a power generation system using a solar panel as a power generation unit. The converter b to which the solar panel a is connected and the DC power boosted by the converter b are used. An inverter c that converts AC power having a frequency connectable to a system power source (power system) d is provided as a main part, and these are connected via a DC link capacitor (DC link part) e.

  In the power conditioner shown in FIG. 3, in order to always supply power to the control microcomputer f that controls each part of the power conditioner, the driving power source (insulated power source) g of the microcomputer f is the above DC. It is comprised so that electric power supply may be received from the link part e.

  Specifically, in the power conditioner shown in FIG. 3, when the solar panel a is generating power, the power generated by the solar panel a is supplied to the DC link part e via the converter b, and When the solar panel a is not generating power, such as at night, or when there is little sunlight and the solar panel a is not generating enough power, the opening / closing provided on the line that supplies power from the system power supply d to the DC link part e The AC power (AC 200V) supplied from the system power supply d is rectified by the rectifier i and converted to DC power and applied to the DC link unit e (in this way, the DC link unit For example, refer to Patent Document 1 for a configuration for supplying power from a power source to a power source.

JP 2011-49053 A

  However, the power conditioner having such a configuration has the following problems, and improvement has been desired.

  That is, in this type of power conditioner, an electrolytic capacitor having a large capacity is used as the capacitor used in the DC link section e. Therefore, as described above, the switch h is closed to supply power from the system power supply d. When the switch h is closed while the voltage of the DC link unit e is low (when power supply from the system power supply d is started), a large inrush current is supplied to the DC link unit e. Will flow. Therefore, conventionally, in a power conditioner employing such a configuration, an expensive electronic component that can withstand a large inrush current has to be employed, leading to an increase in component cost.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a power conditioner that can reduce inrush current when power is supplied from the power system to the DC link unit. There is.

  In order to achieve the above object, a power conditioner according to claim 1 of the present invention is capable of interconnecting a converter that boosts DC power generated by a power generation unit and DC power boosted by the converter to a power system. In a power conditioner that has an inverter for converting the AC power into the AC link and these are connected via the DC link unit, it is possible to supply power from the power system to the DC link unit without passing through the inverter. When power supply to the DC link unit is started through the system power supply unit, the converter is operated in advance so that the voltage of the DC link unit is at least applied to the DC link unit. It has a control configuration in which the voltage is boosted to be equal to or higher than the voltage of the supplied power system.

  That is, in the power conditioner according to the first aspect, when the power supply from the power system to the DC link unit is started by the system power supply means, the converter is operated in advance and the voltage of the DC link unit is set in advance. The voltage is boosted to be equal to or higher than the voltage of the power system. Therefore, according to this power conditioner, when the power supply from the power system to the DC link unit is started, the potential difference between the DC link unit and the power system is small (or the voltage of the DC link unit is larger than the voltage of the power system). Therefore, even if power supply from the power system is started, it is possible to avoid a large inrush current from flowing from the power system side to the DC link unit.

  Here, the equivalent to the voltage of the power system preferably means the same voltage value as the voltage value of the power system, but a large inrush current does not flow when power supply from the power system to the DC link unit is started. If it is within the range, it is meant to include a voltage value lower than the voltage value of the power system, for example, a value close to the voltage value of the power system.

  A power conditioner according to a second aspect of the present invention is the power conditioner according to the first aspect, wherein the operation of the converter prior to the power supply to the DC link unit by the system power supply means is the same as that of the converter. Is performed on condition that the voltage of the DC link unit before the operation of the converter is equal to or higher than a predetermined threshold voltage set according to the boosting capability of the converter, and the voltage of the DC link unit before the operation of the converter is When the voltage is less than a predetermined threshold voltage, power supply to the DC link unit by the system power supply means is not performed.

  That is, as described above, when supplying power from the power system to the DC link unit, the power conditioner of the present invention operates the converter in advance to boost the voltage of the DC link unit and Therefore, in the power conditioner according to claim 2, the voltage of the DC link part before the converter operation is too low. If it is predicted that the DC link voltage cannot be boosted to a value equal to or higher than the voltage of the power system even if the converter is operated (below the predetermined threshold voltage), operate the converter in this state. However, if power supply from the power system is started after that, a large inrush current flows. In that case, the power system must be operated without operating the converter. It is not carried out the power supply itself to the DC link section.

  In the power conditioner according to claim 3 of the present invention, in the power conditioner according to claim 1 or 2, the output voltage of the power generation unit is set as a start condition of the grid interconnection operation by the power conditioner. When the interconnection operation allowable voltage is exceeded, the power supply to the DC link unit by the grid power supply means is not performed.

  That is, in the power conditioner according to the third aspect, when the output voltage of the power generation unit exceeds a predetermined voltage value (interconnection operation allowable voltage) set as a start condition of the grid connection operation of the power conditioner. Since power is not supplied to the DC link unit by the grid power supply means, for example, the power that can be connected to the grid by the power generation unit is supplied from the power system to the DC link unit. When power generation can be performed, power supply from the power system to the DC link unit is stopped. That is, in this case, when the power conditioner starts the grid connection operation, the DC link unit is supplied with the power boosted by the converter.

  A power conditioner according to a fourth aspect of the present invention is the power conditioner according to any one of the first to third aspects, wherein the converter is a non-insulated DC-DC converter. And

  That is, in the power conditioner according to the fourth aspect, since the converter is configured by a non-insulated DC-DC converter, the power generated by the power generation unit is not affected by the converter, and the DC link unit Will be supplied to. Therefore, for example, even when the voltage of the DC link unit before the operation of the converter is less than the predetermined threshold voltage and power supply to the DC link unit by the system power supply unit is not performed, the DC link The unit is supplied with power generated by the power generation unit.

  A power conditioner according to a fifth aspect of the present invention is the power conditioner according to any one of the first to fourth aspects, wherein a driving power source of a microcomputer for controlling the power conditioner is connected to the DC link portion. It is characterized by being.

  That is, in the power conditioner according to the fifth aspect of the present invention, since the drive power source of the control microcomputer for the power conditioner is supplied with power from the DC link unit, the drive power source is connected via the DC link unit. The power can be supplied from both the power generation unit and the power system, and the DC link unit can be used not only when the power conditioner performs grid connection operation but also when the grid connection operation is not performed. It is possible to receive power supply, and even when the power conditioner is not performing grid connection operation, it is possible to continue monitoring the equipment by the microcomputer.

  According to the present invention, in the power conditioner in which the converter and the inverter are connected via the DC link unit, the grid power supply means that can supply power from the power system to the DC link unit without passing through the inverter. When the power supply to the DC link unit is started through this system power supply means, the converter is operated in advance to boost the voltage of the DC link unit to a value equal to or higher than the voltage of the power system. Therefore, a large inrush current is prevented from flowing when power from the power system is supplied to the DC link unit by the system power supply means. Therefore, it is not necessary to employ an electronic component that can withstand a large inrush current as a component of the power conditioner, an increase in component cost can be avoided, and an inexpensive power conditioner can be provided.

It is a circuit block diagram which shows schematic structure of the electric power generation system using the power conditioner which concerns on this invention. It is a flowchart which shows an example of the procedure of the electric power supply to the DC link part in the power conditioner. It is a circuit block diagram which shows schematic structure of the electric power generation system using the conventional power conditioner.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
An example of a power generation system using the power conditioner according to the present invention is shown in FIG. The power generation system shown in FIG. 1 is a power generation system including a solar panel 1 as a power generation unit, and is an inverter for connecting DC power generated by the solar panel 1 to a system power source (power system) 2. A power conditioner 3 is provided as a device.

  The solar panel 1 is a well-known power generation device formed by unitizing a plurality of power generation elements (solar cells) that generate power by a photoelectric phenomenon into a panel shape. Two electrical cables 20a and 20b for positive electrode and negative electrode are provided as output means, and these two electrical cables 20a and 20b are input terminals (not shown) for inputting generated power in the power conditioner 3. )It is connected to the.

  In addition, although the case where the solar panel 1 was comprised by one sheet was shown in the example of illustration, the solar panel 1 used as a power generation part is not restricted to one sheet, You may use the several solar panel 1. FIG. However, in that case, a connection box is provided between the solar panel 1 and the power conditioner 3 to collect the DC power output from the plurality of solar panels 1 into two electrical cables. Two electric cables for the positive electrode and the negative electrode arranged in the box are connected to the input terminal (not shown) of the power conditioner 3.

  The system power supply 2 is composed of an AC power supply such as a commercial power supply. In this embodiment, a single-phase three-wire AC 200 V AC power source is used as the system power source 2. The system power supply 2 is connected to a power conditioner 3 and a household power load (not shown) through a distribution board (not shown).

  As described above, the power conditioner 3 is an inverter device for connecting the DC power generated by the solar panel 1 to the system power supply 2, and the power conditioner 3 includes the solar panel 1. A converter 4 for boosting the generated DC power, an inverter 5 for converting the DC power boosted by the converter 4 into AC power that can be connected to the system power supply 2, and the converter 4 and the inverter 5 A DC link unit 6 to be connected, a system interconnection relay 7 for linking the AC power converted by the inverter 5 to the system power source 2, and a microcomputer (control microcomputer) 8 for controlling each part of the power conditioner 3 And the drive power source 9 of the microcomputer 8 as a main part. In the power conditioner 3 of this embodiment, in addition to these, 5 is provided with system power supply means 10 for supplying power to the DC link unit 6 from the system power supply 2 side without going through 5, and the solar panel 1 generates power such as during the daytime and will be described later. From the solar panel 1 side when performing grid interconnection operation, and from the grid power source 2 side when the solar panel 1 is not generating power and performing grid interconnection operation such as at night The DC link unit 6 is configured to supply power (details will be described later).

  The converter 4 is constituted by a DC-DC converter. In this embodiment, a non-insulated step-up chopper type DC-DC converter is used as the converter 4. The input side of the converter 4 is connected to an input terminal (not shown) of the generated power of the solar panel 1 so that DC power generated by the solar panel 1 is input. The output side of the converter 4 is connected to the inverter 5 via the DC link unit 6. Here, the DC link unit 6 is configured by connecting an electrolytic capacitor 21 serving as a DC link capacitor between electrical lines connecting the converter 4 and the inverter 5.

  The inverter 5 is composed of a DC-AC inverter, and the grid connection relay 7 is connected to the output side of the inverter 5, and the output side of the inverter 5 is connected to the power conditioner 3 via the grid connection relay 7. The terminal block 11 is connected. The grid connection relay 7 can be controlled to open and close by a microcomputer 8 described later.

  The terminal block 11 is a terminal block connected to the system power source 2 via a distribution board (not shown). In the present embodiment, a single-phase three-wire power source is used for the system power source 2, The terminal block 11 is provided with three terminals (not shown) for connecting the U-phase, V-phase and N-phase (grounded neutral wire) of the system power supply 2. (That is, the output of the grid interconnection relay 7) is connected to the U-phase and V-phase terminals of the terminal block 11.

  The microcomputer 8 constitutes a control means for controlling each part of the power conditioner 3. The microcomputer 8 stores a control program for performing various controls described later, control data, and the like. Yes. The microcomputer 8 is connected to various sensors (not shown). Based on information from these sensors, the microcomputer 8 determines the power generation status (output voltage) of the photovoltaic power generation panel 1 and the system power supply. 2 is configured to acquire various types of information related to the power generation system, such as power supplied from 2 (purchased power) and power consumed by an indoor power load (power consumption).

  The drive power supply 9 is a power supply device for generating power to be supplied to the microcomputer 8. The drive power supply 9 is connected to both ends of the electrolytic capacitor 21 constituting the DC link unit 6 and is configured to generate power to be supplied to the microcomputer 8 by receiving power supply from the DC link unit 6. That is, the drive power supply 9 is constituted by a DC-DC converter that converts the voltage of the DC link unit 6 into a voltage that can be supplied to the microcomputer 8. The drive power supply 9 is an insulating power supply device that connects the DC link unit 6 and the microcomputer 8 in an insulated state.

  The system power supply means 10 is a power supply path provided for supplying power from the system power supply 2 to the DC link unit 6 without going through the inverter 5, and more specifically, the terminal block 11 and the DC link. It is comprised by the electrical equipment wire which connects the part 6 and the electrical components which have the nighttime feeding relay (switch) 13 provided in this electrical equipment wire 12 and the rectifier 14 as a main part.

  More specifically, the electrical wiring 12 is composed of two electrical wirings 12a and 12b, and the two electrical wirings 12a and 12b are used to extract 100 VAC power from the terminal block 11. ing. That is, one end of one of the electrical wires 12 is connected to the U phase or V phase (V phase in the illustrated example) of the terminal block 11 and one end of the other electrical wire 12b is connected to the terminal block. 11 is connected to the N phase, and AC 100 V is taken out from AC 200 V supplied to the terminal block 11 from the system power supply 2 and can be used as power supplied to the DC link unit 6.

  The other end of the electrical wire 12 a is connected to the positive electrode of the electrolytic capacitor 21 constituting the DC link portion 6, and the other end of the electrical wire 12 b is connected to the negative electrode of the electrolytic capacitor 21.

  The nighttime power supply relay 13 is a switch for supplying the power of the system power supply 2 to the DC link unit 6 at nighttime when the solar panel 1 does not generate power. Opening and closing control can be performed by the microcomputer 8 in the same manner as the contact of the grid interconnection relay 7.

  The rectifier 14 is a rectifier for converting AC 100V AC power supplied from the system power supply 2 via the night power feeding relay 13 into DC power and supplying the DC power to the DC link unit 6. A diode bridge circuit (full-wave rectifier circuit) is used as the rectifier 14. In addition, electronic parts such as a fuse 15 and a PTC thermistor (or resistor) 16 for preventing an overcurrent are disposed on the electrical line 12.

Next, the operation of the power conditioner 3 configured as described above will be described.
The power conditioner 3 shown in the present embodiment boosts the DC power generated by the solar panel 1 by the converter 4 and supplies it to the inverter 5, which converts the DC power into AC power that can be connected to the system power supply 2. Are connected to the system power supply 2 via the system connection relay 7, but the system connection operation by the power conditioner 3 (the system connection relay is operated by operating the converter 4 and the inverter 5). 7 is a condition under which the voltage input from the solar panel 1 to the power conditioner 3 (that is, the output voltage of the solar panel 1) Vin starts the grid interconnection operation in the power conditioner 3. Is performed when a predetermined interconnection operation allowable voltage Von set in advance is exceeded (when Von <Vin).

  Here, the interconnection operation allowable voltage Von generates AC power that can be linked to the system power supply 2 by operating the converter 4 and the inverter 5 in the power conditioner 3 (AC power of AC 200 V in this embodiment). The lower limit voltage (or voltage near the lower limit voltage) of the input voltage to the power conditioner 3 that can be set is set.

  The reason why the above-mentioned lower limit voltage is adopted as the interconnection operation allowable voltage Von is that the interconnection operation allowable voltage Von functions as determining the operation start timing of the power conditioner 3 with respect to the power generation amount of the solar panel 1. It is. That is, if the interconnection operation allowable voltage Von is set higher than the lower limit voltage, the start of the grid interconnection operation is delayed by that amount, and the power generated by the solar panel 1 is wasted. Therefore, this interconnection operation allowable voltage Von is set to a value as low as possible in relation to the ability to boost the input voltage in converter 4 (boosting ability). In other words, the interconnection operation allowable voltage Von is supplied by the converter 4 with a DC voltage required for the inverter 5 to generate AC power that can be connected to the system power supply 2 based on the boosting capability of the converter 4. Set as low as possible. In the present embodiment, the interconnection operation allowable voltage Von is set to 70V.

  On the other hand, when the output voltage Vin of the solar panel 1 is equal to or lower than the interconnection operation allowable voltage Von (when Vin ≦ Von), the power conditioner 3 does not perform the above-described grid interconnection operation. In the power conditioner 3, even when the grid connection operation is not performed in this way (that is, when the converter 4 and the inverter 5 are stopped and the grid connection relay 7 is opened), the predetermined condition is satisfied. On the premise of satisfying, the night power feeding relay 13 is closed to supply power from the system power supply 2 to the DC link unit 6.

  Here, even if the power conditioner 3 is not performing the grid connection operation, the power is supplied to the DC link unit 6 from the system power supply 2 side. 3 is because the drive power supply 9 of the microcomputer 8 is supplied with power from the DC link unit 6. That is, in the power conditioner 3 of the present embodiment, the microcomputer 8 always supplies power to the DC link unit 6 even when the grid connection operation is not performed (even if the grid connection operation is not performed). The power generation system can be monitored.

  The predetermined condition in the power conditioner 3 of the present embodiment is that the voltage Vdc of the DC link unit 6 when the converter 4 is in the operation stop state is equal to or higher than a predetermined threshold voltage Vth (Vth ≦ Vdc). It is said that).

  That is, in this power conditioner 3, even when the output voltage Vin of the solar panel 1 is not more than the interconnection operation allowable voltage Von and the grid interconnection operation is not performed, the voltage Vdc of the DC link unit 6 is If it is above the threshold voltage Vth, the microcomputer 8 is configured to close the night power supply relay 13 and start power supply from the system power supply 2 to the DC link unit 6.

  By the way, on the assumption that the predetermined condition is satisfied, if the configuration in which the night power feeding relay 13 is immediately closed is adopted, the voltage Vdc of the DC link unit 6 is the voltage of the power supplied from the system power supply 2 (in this embodiment). There is a possibility that a large inrush current flows in the DC link portion 6 due to being lower than AC100V supplied to the night power feeding relay 13.

  Therefore, in the power conditioner 3 of the present embodiment, even if the predetermined condition is satisfied, the microcomputer 8 does not immediately close the night power feeding relay 13 but immediately closes the night power feeding relay 13. The voltage Vdc of the DC link unit 6 is the voltage of the system power 2 supplied to the DC link unit 6 (in this embodiment, the DC link unit 6 is configured to be supplied with AC100V of AC200V of the system power 2). Therefore, the voltage of the system power 2 supplied to the DC link unit 6 is increased to the same level as or higher than that of the AC link 2 to prevent a large inrush current from flowing through the DC link unit 6.

  Specifically, even when the output voltage Vin of the solar panel 1 is equal to or lower than the interconnection operation allowable voltage Von, the solar panel 1 has a low output voltage except when there is almost no sunshine such as at night. However, since power generation is performed, the power generated by the solar panel 1 is boosted by the converter 4 and supplied to the DC link unit 6, and the voltage of the DC link unit 6 is supplied to the DC link unit 6. The voltage is boosted to be equal to or higher than the voltage of the system power 2 (AC100V).

  Therefore, in the power conditioner 3 of the present embodiment, the threshold voltage Vth is set according to the boosting capability of the converter 4. That is, the voltage that can be boosted to a voltage equal to or higher than the voltage (AC 100 V) of the grid power 2 supplied to the DC link unit 6 by boosting the converter 4 (the output voltage Vin of the solar panel 1). The threshold voltage Vth is set. The threshold voltage Vth satisfies the relationship of Vth <Von in relation to the interconnection operation allowable voltage Von. In this embodiment, the threshold voltage Vth is set to 40V.

  Therefore, for example, when the boosting capability of converter 4 is seven times, when DC 40 V is input to converter 4, the output voltage of converter 4 is boosted to DC 280 V, which is seven times the DC voltage, To be supplied. Therefore, in this case, the voltage of the system power supply 2 supplied to the DC link unit 6 is AC100V (peak value: about 141V), whereas the converter 4 is supplied with power of DC280V. Even if the nighttime power supply relay 13 is closed in this state, the inrush current does not flow from the system power supply 2 side to the DC link unit 6, and the inrush current to the DC link unit 6 is prevented.

  The power boosted by the converter 4 is supplied to the DC link unit 6 after the night power supply relay 13 is closed by the microcomputer 8, that is, the power supply from the system power supply 2 to the DC link unit 6 can be started. It is released after being done. In other words, since the power from the system power supply 2 can be supplied to the DC link unit 6 by closing the night power feeding relay 13, the operation of the converter 4 is stopped after this power supply is generated.

  FIG. 2 is a flowchart showing a series of operations (processing of the microcomputer 8) in the power conditioner 3. Hereinafter, the procedure described above will be organized and described with reference to FIG.

  When the microcomputer 8 of the power conditioner 3 receives the power supply from the drive power supply 9 and starts its operation, first, the voltage Vdc of the DC link unit 6 is compared with the threshold voltage Vth, and the voltage Vdc of the DC link unit 6 is compared. Is less than the threshold voltage Vth (Vdc <Vth) (see step S1 in FIG. 2).

  If this determination is affirmative, the microcomputer 8 supplies the output voltage Vin of the solar panel 1 to the DC link unit 6 as it is without operating the converter 4 (see step S2 in FIG. 2). That is, in this embodiment, since the converter 4 is a non-insulated step-up chopper DC-DC converter, the output voltage Vin of the solar panel 1 is DC link even when the converter 4 is not operated. Supplied to section 6.

  Here, when the determination in step S1 of FIG. 2 is affirmative, the output voltage Vin of the solar panel 1 is equal to or lower than the above-described interconnection operation allowable voltage Von, and thus the grid interconnection operation of the power conditioner 3 is not performed. . In this state, the microcomputer 8 maintains the night power feeding relay 13 in the open state. That is, in this state, even if the converter 4 is operated as described above, the voltage Vdc of the DC link unit 6 is boosted to a desired voltage (a voltage that can prevent an inrush current when the night power feeding relay 13 is closed). In such a case, the night power feeding relay 13 is maintained in an open state. That is, the microcomputer 8 is configured not to close the night power feeding relay 13 when the voltage Vdc of the DC link unit 6 is less than the threshold voltage Vth.

  In the power conditioner 3 of the present embodiment, as will be described later, when the power generation output of the solar panel 1 is reduced, power is supplied from the system power supply 2 to the DC link unit 6. The case where the judgment of step S1 of FIG. 2 becomes affirmative is limited, for example, when the power supply to the power conditioner 3 is started (during construction) or when the solar panel 1 is not generating power such as at night The process of step S2 in FIG. 2 is performed when the power source 2 has a power failure.

  On the other hand, if the determination in step S1 of FIG. 2 is negative, the microcomputer 8 next determines whether the output voltage Vin of the solar panel 1 is equal to or lower than the interconnection operation allowable voltage Von (Vin ≦ Von). Is determined (see step S3 in FIG. 2). In other words, in step S3 of FIG. 2, the microcomputer 8 determines that the voltage Vdc of the DC link unit 6 is equal to or higher than the threshold voltage Vth (Vth ≦ Vdc), and the output voltage Vin of the solar panel 1 is the above-described interconnection. It is determined whether or not the operation allowable voltage is Von or less (Vin ≦ Von).

  If this determination is affirmative, the microcomputer 8 first operates the converter 4 to boost the output voltage Vin of the solar panel 1 and supply it to the DC link unit 6. Vdc is boosted to a level equal to or higher than the voltage of the system power 2 (AC 100 V) supplied to the DC link unit 6. When the boosting of the DC link unit 6 is completed, the night power feeding relay 13 is then closed, and the power (AC 100 V) supplied from the system power supply 2 via the terminal block 11 is passed through the rectifier 14 to the DC link unit. 6 and then the operation of the converter 4 is stopped (see step S4 in FIG. 2).

  At this time as well, the output voltage Vin of the solar panel 1 is equal to or lower than the interconnection operation allowable voltage Von, and thus the grid interconnection operation of the power conditioner 3 is not performed. That is, except when boosting the voltage of the DC link unit 6, the converter 4 is stopped, the inverter 5 is also stopped, and the grid interconnection relay 7 is maintained open.

  If the determination in step S3 in FIG. 2 is negative, the voltage Vdc of the DC link unit 6 is higher than the threshold voltage Vth (Vth <Vdc) as shown in step S5 in FIG. The output voltage Vin of the panel 1 is higher than the interconnection operation allowable voltage Von (Von <Vin).

  Here, as shown in step S5 of FIG. 2, when the output voltage Vin of the solar panel 1 is higher than the interconnection operation allowable voltage Von, as described above, the power conditioner 3 can perform the grid interconnection operation. In this case, the microcomputer 8 causes the power conditioner 3 to perform the grid connection operation. In other words, the microcomputer 8 opens the night power feeding relay 18 (without supplying power to the DC link unit 6 by the system power supply means 10), and the converter 4 and the inverter 5 are in the operating state, thereby connecting the system interconnection relay. 7 is closed. Therefore, in this case, the DC link unit 6 is supplied with power generated by the solar panel 1 and boosted by the converter 4 (see step S6 in FIG. 2).

  When the power conditioner 3 is in the grid connection operation, the microcomputer 8 determines whether the output voltage Vin of the solar panel 1 is not more than the above-described interconnection operation allowable voltage Von (Vin ≦ Von). For example, whether or not the amount of power generated by the solar panel 1 has been reduced due to a decrease in sunshine or the like is regularly or periodically determined (see step S7 in FIG. 2). The system operation is stopped (that is, the operation of the converter 4 and the inverter 5 is stopped and the system interconnection relay 7 is opened), and the nighttime power supply relay 13 is closed, so that the DC link unit 6 is connected to the system power supply 2 side. The power supply from is started.

  When the night feeding relay 13 is closed in the process of step S8 in FIG. 2, the power generated by the solar panel 1 is supplied to the DC link unit 6 until just before that, and in this state, the DC link unit Since the voltage Vdc of 6 is higher than the voltage supplied from the system power supply 2, no inrush current flows through the DC link unit 6 even when the night power feeding relay 13 is closed.

  Thus, in the power conditioner 3 according to the present invention, the voltage Vdc of the DC link unit 6 is not less than the predetermined threshold voltage Vth (Vth ≦ Vdc), and the output voltage Vin of the solar panel 1 is the power conditioner 3. In the case where a certain condition such as the interconnection operation allowable voltage Von or less (Vin ≦ Von) is satisfied, when the power supply to the DC link unit 6 is started through the grid power supply means 10, the converter 4 Is operated to boost the voltage of the DC link unit 6 at least equal to or higher than the voltage of the power system 2 supplied to the DC link unit 6, so that the night power supply relay 13 is closed in this state. In addition, a large inrush current does not flow to the DC link unit 6 from the power system 2 side.

  Therefore, according to the power conditioner 3 according to the present invention, it is not necessary to use an expensive electronic component that can withstand a large inrush current as a component of the power conditioner 3. A power conditioner can be provided. Specifically, inexpensive parts having a small current capacity can be adopted as the fuse 15, the PTC thermistor 16, and the nighttime power supply relay 13 of the system power supply means 10, and these costs can be suppressed.

  The above-described embodiments show preferred embodiments of the present invention, and the present invention is not limited to these, and various design changes can be made within the scope of the invention.

  For example, in the above-described embodiment, the case where the electrical wires 12a and 12b of the system power supply means 10 are wired so as to extract AC 100V power from the terminal block 11 is shown, but this causes the night power supply relay 13 to be closed. In order to reduce the inrush current to the DC link unit 6 at the time, the voltage taken out from the terminal block 11 is lowered, so that the inrush current to the DC link unit is sufficiently suppressed by setting the threshold voltage Vth and the like. If possible, it is also possible to connect the electrical wires 12a and 12b to the U phase and V phase of the terminal block 11 so as to take out AC200V power from the system power supply 2.

  In the above-described embodiment, the threshold voltage Vth is 40 V and the interconnection operation allowable voltage Von is 70 V. These values are determined by the voltage of the system power supply 2 and the boosting capability of the converter 4. Of course, specific numerical values can be set and changed as appropriate.

  Further, in the above-described embodiment, the case where the microcomputer 8 receives power supply from the drive power supply 9 has been described. For example, a remote controller (not shown) of the power conditioner 3 configured separately from the power conditioner 3. Alternatively, the drive power supply 9 can be configured to supply power to parts other than the microcomputer 8 such as a display device (not shown) installed in the power conditioner 3. As a result, these remote controllers and display devices can be operated and displayed while the grid connection operation is stopped.

  Further, in the above-described embodiment, the case where the voltage Vdc of the DC link unit 6 is compared with the threshold voltage Vth in the control of the power conditioner 3 has been described. Since the chopper method is employed, the input voltage to the power conditioner 3, that is, the output voltage Vin of the solar panel 1 can be used instead of the voltage Vdc of the DC link unit 6.

  In the above-described embodiment, when a voltage comparison between a preset voltage such as the threshold voltage Vth and the interconnection operation allowable voltage Von and a measured voltage such as the output voltage Vin of the solar panel 1 is performed, hysteresis is performed. It is desirable to take measures to prevent control hunting, such as providing voltage and settling time.

1 Solar panel (power generation unit)
2 system power supply (electric power system)
3 Power conditioner 4 Converter 5 Inverter 6 DC link section 7 System interconnection relay 8 Microcomputer (control microcomputer)
9 Driving power supply 10 System power supply means 11 Terminal block 12 Electrical equipment line 13 Night feeding relay (switch)
14 Rectifier

Claims (5)

A converter that boosts the DC power generated by the power generation unit and an inverter that converts the DC power boosted by the converter into AC power that can be connected to the power system, which are connected via the DC link unit In the inverter that is
System power supply means for enabling power supply from the power system to the DC link unit without going through the inverter,
When power supply to the DC link unit is started through the system power supply means, the converter is operated in advance, and the voltage of the DC link unit is at least equal to the voltage of the power system supplied to the DC link unit. A power conditioner having a control configuration for boosting as described above.   The operation of the converter performed prior to the power supply to the DC link unit by the grid power supply means is a predetermined threshold at which the voltage of the DC link unit before the operation of the converter is set according to the boosting capability of the converter If the voltage of the DC link unit is less than the predetermined threshold voltage before the operation of the converter, the power supply to the DC link unit by the system power supply unit The power conditioner according to claim 1, wherein the inverter is not performed.   When the output voltage of the power generation unit exceeds the interconnection operation allowable voltage set as the start condition of the grid interconnection operation by the power conditioner, the grid power supply means supplies power to the DC link unit. The power conditioner according to claim 1 or 2, wherein there is no power conditioner.   4. The power conditioner according to claim 1, wherein the converter is a non-insulated DC-DC converter.   The power conditioner according to any one of claims 1 to 4, wherein a drive power source of a microcomputer for controlling the power conditioner is connected to the DC link unit.

Images