KR101020789B1 - Grid-connected hybrid solar photovoltaic generation system having uninterruptible power supply - Google Patents

Abstract

PURPOSE: A hybrid photovoltaic generation system is provided to stably supply power by efficiently combining a photovoltaic generation with a battery generation. CONSTITUTION: A PV converter(600) converts photovoltaic power into a DC voltage. A battery charging/discharging converter(200) reduces the output voltage of the PV converter to a battery charging voltage. The battery charging/discharging converter boosts the voltage of the battery to the voltage for operating an inverter. An inverter rectifier(400) converts the DC power of the battery into AC power and converts the power of the system into the DC power. A system connection relay(310) separates the output of the inverter from a system(300) when the power is off in the system. A charging/discharging relay(210) separates a battery charging/discharging unit from the inverter rectifier. A controller(800) controls the photovoltaic generation system.

Description

Grid-connected hybrid solar photovoltaic generation system having uninterruptible power supply

The present invention relates to a grid-connected hybrid photovoltaic power generation system having an uninterruptible function, and more specifically, to the grid and the load when the grid is connected, the grid power and the battery generation power when the load is linked Basically, it outputs constant constant power to the load by using it.It cuts off the system to prevent reverse current during power outage and supplies power to the load to prevent problems caused by power failure. The present invention relates to a grid-connected hybrid solar power generation system having an uninterruptible function.

That is, the present invention efficiently combines a PV (Photovoltaic) converter that controls the photovoltaic power by the MPPT algorithm and a battery charge-discharger that operates in response to a system power failure or load change. It supplies solar power to the overload, and separates the battery from the circuit when the grid is connected, and operates as a grid-connected solar inverter that supplies solar power. The present invention relates to a grid-connected hybrid solar power generation system having an uninterruptible function of preventing accidents and supplying solar power to loads.

As is well known to those skilled in the art, conventional photovoltaic systems are broadly divided into grid-connected and standalone. A grid-connected photovoltaic power generation system is used for the photovoltaic power generation business, and the configuration of one embodiment is shown in FIG. 1. On the other hand, a standalone solar power system is used in island areas where grid power supply is difficult for power supply companies such as KEPCO, and the configuration of one embodiment is shown in FIG. 2. 1 and 2, the reference numeral 10 is a DC bus, 20 is a battery charger-discharger, 22 is a battery, 30 is a system, 40 is an inverter, 50 is a load, 60 is a PV converter, 70 indicates a solar cell, These members are well known to those skilled in the art.

Grid-connected photovoltaic power generation system as shown in Figure 1 is typically used for the purpose of a business operator to supply the generated power to the grid 30 to obtain a profit through power sales.

Standalone photovoltaic power generation system as shown in Figure 2 is typically used in islands and the like without a power system by a power supply company, such as KEPCO, the power to the load 50 by a battery and a separate generator and cooperative operation It is used in the form of supplying. Incorporating the functions of the photovoltaic power generation system used in this particular situation to supply high-quality power to the load (50) stage, and to sell the surplus power generated in the solar cell 70 through the system (30) to raise profits In addition, it is required to develop a solar cell system having a multi-function function to charge the battery 22 by using low-cost late-night power of the late-night time, and make a profit by the generation difference.

The present invention has been made in view of the above-described existing technical matters, by linking the system and the load according to the situation, the grid connection with the uninterrupted function of disconnecting the grid connection in case of power failure and sending the generated power of the solar cell to the load. Its purpose is to provide a hybrid hybrid solar power system.

In order to achieve the above object, a grid-tied hybrid photovoltaic power generation system having an uninterruptible function according to the present invention includes: a PV (Photovoltaic) converter for converting photovoltaic power generation by a solar cell into a DC voltage; A battery charge-discharge converter for stepping down the output voltage of the PV converter to a battery charging voltage and step-up of the voltage of the battery to a voltage at which the inverter operates; Converting the DC power of the photovoltaic power source and the battery power into AC power to supply the system and the load, or converting the system power into DC power to supply the battery to the battery for use as charging power of the battery. Inverter / rectifier; A grid connection relay separating the inverter output from the inverter / rectifier and the grid during a power failure of the grid; A charge-discharge relay that separates the battery charge-discharger from an inverter / rectifier when the system is connected to the solar power source; And a controller for controlling the solar power generation system and controlling the PV converter, the battery charge-discharge converter, the inverter / rectifier, the grid connection relay, and the charge-discharge relay.

Preferably, when the power generated by the solar power supply is greater than the load amount, the PV converter is operated in a maximum power following (MPPT) control scheme, and the surplus power remaining after supplying to the load is supplied to the system, wherein the charging The discharge relay separates the battery charger-discharger from the inverter.

Preferably, when the power generated by the solar power supply is smaller than the load amount, the insufficient power is supplied from the battery to always supply the constant power required by the load.

Preferably, when the battery requires charging, the power generated by the solar power source is decompressed to be used for charging the battery first, and the remaining power is supplied to the load.

Preferably, the grid connection relay is opened and separated from the grid when the grid power is interrupted, and solar power is supplied to the load, and when the solar power generation is not possible, power generated through the battery is supplied to the load. .

Preferably, when power generation from the solar power source is not possible, power is supplied from the system to the load, and the inverter operates as a PFC (Power Factor Correction) rectifier for compensating and controlling the power factor of the inverter during a late night time zone having a low power rate. Supply the system power to charge the battery.

The grid-connected hybrid solar power generation system having an uninterruptible function according to the present invention is a solar power generation system having a grid-linked function and a stand-alone function, and has a function of supplying generated power to a load during a power failure. The inverter / rectifier acts as a rectifier to reduce the power cost by applying the technology to charge the battery using the midnight power, and provides the advantage of supplying stable constant power to the load stage.

1 is a block diagram of an embodiment of a grid-connected photovoltaic power generation system according to the prior art.
2 is a block diagram of an embodiment of a stand-alone photovoltaic power generation system according to the prior art.
3 is a block diagram of a grid-type hybrid solar power generation system having an uninterruptible function according to the present invention.
4 is a block diagram of a grid-connected hybrid solar power system having an uninterruptible function according to an embodiment of the present invention.
Figures 5a to 5c is a power flow chart according to the load in the operation of the present invention, the solar power is a normal operation,
5A illustrates a case where the generated power of the solar cell is greater than the load amount and the battery charging power.
5B illustrates a case in which the generated power of the solar cell is smaller than the load, and the combined power of the solar cell generated power and the battery power is larger than the load.
5C illustrates a case where the combined amount of power generated by the solar cell and the battery power is smaller than the load amount.
6a to 6c is a power flow chart according to the load in the absence of solar power in the operation of the present invention,
Figure 6a is a case where the battery power is greater than the load when there is no power generation of the solar cell,
6B illustrates a case in which the battery power is smaller than the load power when there is no generating power of the solar cell.
Figure 6c is a power flow chart of the late night power time when there is no power generation of the solar cell.
7A to 7C are diagrams illustrating a power flow chart during system power failure in the operation of the present invention.
7A illustrates a case where the generated power of the solar cell is greater than the load amount and the battery charging power during grid power failure.
FIG. 7B illustrates a case where the generated power of the solar cell is smaller than the load during system power failure, and the combined power of the solar cell generated power and the battery power is greater than the load.
7C illustrates a case in which there is no generated power of the solar cell at the time of grid power failure.
8 is a power flow chart when the battery requires charging in the operation of the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of a grid-type hybrid solar power system having an uninterruptible function according to the present invention. In the following description of the present invention, when it is determined that detailed descriptions of related well-known technologies or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intention or custom of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

Referring to FIG. 3, a grid-connected hybrid solar power generation system having an uninterruptible function according to the present invention includes a PV (Photovoltaic) converter 600 between an input terminal of a solar cell 700 and a grid 300 and a load 500. ), The battery 220, the battery charge-discharge converter 200, the charge-discharge relay 210, the inverter / rectifier 400 are sequentially connected. In addition, the present invention controls the PV converter 600 and the battery 220, the battery charge-discharge converter 200, the charge-discharge relay 210, the inverter / rectifier 400, the system-linked hybrid It includes a control unit 800 for controlling the solar power system as a whole. The controller 800 may preferably include a microprocessor.

The PV converter 600 serves to supply a DC voltage input from the solar cell 700 to the DC bus 100 controlled by a maximum power point tracking (MPPT) method. In order to supply the DC voltage input from the solar cell 700 to the DC bus 100 by the PV converter 600, the PV converter 600 and the DC bus ( A battery 220 and a battery charge-discharge converter 200 are interposed between the batteries 100 and 100.

The battery charge-discharge converter 200 may reduce the voltage supplied to the DC bus 100 when charging, supply the battery 220 to the battery 220, and during discharge, boost the voltage of the battery 220 to boost the DC bus 100. To supply. The charge-discharge relay 210 serves to electrically separate the DC bus 100 and the battery charge-discharger 200. The inverter / rectifier 400 converts the power generated from the solar cell 700 and the battery 220 into alternating current power to supply the system 300 and the load 500, and operates as a rectifier during the late night hours. To charge the battery 220 using the late-night power bill.

In one embodiment of the present invention, the PV converter 600 is preferably capable of boosting and outputting the voltage of the solar cell 700 by operating as a boost converter according to the MPPT control method. do. The battery charge-discharge converter 200 preferably operates as a boost converter when the generation power of the solar cell 700 is insufficient or there is no generation power to provide the power required by the load 500. In addition, when the load of the load 500 is smaller than the generated power of the solar cell 700 and the battery 220 requires charging, the battery charge-discharge converter 200 operates as a buck converter to operate the battery 220. ) Is preferably charged under reduced pressure. Charge-discharge relay 210 is preferably open when sending the generated power of the solar cell 700 to the system 300, by separating the DC bus 100 and the battery 220 of the solar power generation system of the present invention Operate with this grid-connected photovoltaic power generation system and operate in a short circuit in other cases. On the other hand, the grid connection relay 310 is preferably short-circuited during grid connection so that the output of the system 300 and the inverter 400 are connected, and in the event of a power failure, the grid connection relay 310 is separated from the system 300 to separate the inverter 400 of the inverter 400. Causes the output to be connected to the load 500.

Hereinafter, the operation of the grid-type hybrid solar power generation system having an uninterruptible function according to the present invention configured as described above will be described in detail with reference to FIGS.

For reference, Figure 3 controls the entire photovoltaic power generation system according to the present invention, the corresponding components, that is, PV converter 600 and battery 220, battery charge-discharge converter 200, charge-discharge relay The control unit 800 for controlling the control unit 210, the inverter / rectifier 400, and the like is illustrated. However, in FIG. 5 to FIG. 8, the control unit is omitted for the sake of simplicity.

3 is a circuit diagram illustrating a grid-connected hybrid photovoltaic power generation system having an uninterruptible function according to an embodiment of the present invention, and FIG. 4 is a block diagram corresponding to FIG. 3.

3 or 4, the grid-connected hybrid solar power generation system having the uninterruptible function of the present invention includes a PV converter 600 and a battery 220 for supplying generation power of the solar cell 700. It includes a battery charge-discharge converter 200 to discharge, the inverter 400 to convert the DC power into AC power to supply the system 300 and the load 500, these are controlled by the controller 800 do.

The PV converter 600 supplies a DC voltage boosted by the maximum power point tracking (MPPT) control scheme to the voltage generated in the solar cell 700 to the DC bus 100 under the control of the controller 800. The battery charge-discharge converter 200 boosts the voltage of the battery 220 when the solar power generated by the solar cell 700 is smaller than the load of the load 500 under the control of the controller 800. When supplied to the bus bar 100 and the battery 220 requires charging, the voltage of the DC bus 100 is reduced to charge the battery 220. When the inverter / rectifier 400 supplies the photovoltaic power of the solar cell 700 or the power of the battery 220 to the load 500 or the system 300 under the control of the controller 800, a direct current is applied. The inverter operates as an inverter for converting power into AC power, and operates as a rectifier in a late-night time when solar power generation of the solar cell 700 is impossible, thereby converting AC power of the system 300 to DC to charge the battery 220.

The charge-discharge relay 210 may be opened when the output of the inverter / rectifier 400 is connected to the system 300 under the control of the controller 800, and thus may be connected to the battery charge-discharge converter 200 and the DC bus line 100. ), And in other cases a short circuit to connect the battery charge-discharge converter 200 and the DC bus 100. On the other hand, the grid connection relay 310, under the control of the control unit 800, is open when the system 300 is a power failure or when the power of the battery 220 to the DC bus line 100, the inverter / rectifier ( 400 and the system 300 are separated, and in other cases, a short circuit is connected to the inverter / rectifier 400 and the system 300.

5A, 5B, and 5C illustrate a current flow state according to the load of the load 500 in a state in which solar power generation is possible in the operation of the present invention. That is, these drawings show that the solar power generated in the solar cell 700 is boosted through the PV converter 600 and supplied to the DC bus line 100, and the solar power is supplied to the grid 300 through the inverter 400. ) And a power flow diagram supplied to the load 500.

FIG. 5A illustrates a state in which surplus power of the generated power of the solar cell 700 is supplied to the system 300 as a power flow when the generated power of the solar cell 700 is greater than the load power of the load 500.

5B is a power flow diagram in which the generated power of the solar cell 700 is smaller than the load, and the combined power of the generated power of the solar cell 700 and the power of the battery 220 is greater than the load of the load 500. It indicates a state in which the battery 220 supplies the amount of insufficient power supplied from the generated power of the battery 700, wherein the grid connection relay 310 is opened, disconnected from the grid 300, the load ( The power flow diagram shows a state in which the constant constant power required by the 500 is supplied only to the load 500.

FIG. 5C is a power flow when the combined power of the solar cell 700 and the power of the battery 220 are smaller than the load of the load 500. In this case, the insufficient load power may be directly supplied from the system 300. It shows the power flow chart of the state.

6A, 6B, and 6C illustrate power flows when the solar cell 700 is impossible to generate as an embodiment of the present invention. 6A, 6B, and 6C, power of the battery 220 is boosted through the battery charge-discharge converter 200 and supplied to the DC bus 100, and the power of the battery 220 drives the inverter 400. Power flow diagrams supplied to the system 300 and the load 500 are shown.

6A is a power flow when the power of the battery 220 is greater than the load of the load 500, and maintains the form of supplying only the same power as the load of the power of the battery 220, and the grid connection relay 310 is opened. Thus, the system 300 is not supplied with power.

FIG. 6B is a flow chart illustrating that the power of the battery 220 is shorter than the load of the load 500, and the power supply of the battery 220 is shorted to supply the amount of power to the load 500 from the system 300. Power flow chart.

6C illustrates that when the battery 220 needs to be charged with the power flow of the late night time, the inverter / rectifier 400 operates as a rectifier to convert AC power of the system 300 into DC power to charge the battery 220. The power flow diagram of the state is shown.

7A, 7B and 7C are power flow diagrams in the case of a system power failure as an embodiment of the present invention. That is, FIGS. 7A, 7B, and 7C are diagrams illustrating a power flow diagram in which the grid connection relay 310 is opened at the time of grid interruption, disconnects from the grid 300, and the generated power is supplied to the load 500 through the inverter 400. Indicates.

FIG. 7A is a power flow when the generated power of the solar cell 700 is greater than the load power of the load 500. The state in which surplus power of the generated power of the solar cell 700 is used to charge the battery 220 is illustrated. Indicates.

FIG. 7B is a power flow diagram when the generated power of the solar cell 700 is smaller than the load, and the combined power of the generated power of the solar cell 700 and the power of the battery 220 is greater than the load of the load 500. It indicates a state in which the battery 220 supplies the amount of insufficient power supplied from the generated power of the battery 700.

FIG. 7C illustrates a power flow diagram in which the battery 220 bears all of the load power as the power flow in a time when it is impossible to generate the solar cell 700.

FIG. 8 illustrates that when the power of the solar cell 700 is normally generated, the grid connection relay 310 is opened in a state where the battery 220 requires charging, thereby separating the inverter / rectifier 400 from the grid. In this case, a power flow diagram is shown when surplus power remaining after supplying to the load 500 is used to charge the battery 220.

Although a preferred embodiment of the present invention has been described in detail above, those skilled in the art to which the present invention pertains, various embodiments of the present invention without departing from the spirit and scope of the invention defined in the appended claims It will be appreciated that modifications or variations may be made. Therefore, changes in the future embodiments of the present invention will not depart from the technology of the present invention.

100: DC bus 200: battery charger-discharger
210: charge-discharge relay 220: battery
300: grid 310: grid connection relay
400: Inverter / Rectifier 500: Load
600: PV converter 700: Solar cell
800: control unit

Claims (7)

In a grid-tied hybrid solar power system having an uninterruptible function,
PV (Photovoltaic) converter for converting the photovoltaic power generation by the solar cell to DC voltage;
A battery charge-discharge converter for stepping down the output voltage of the PV converter to a battery charging voltage and step-up of the voltage of the battery to a voltage at which the inverter operates;
Converting the DC power of the photovoltaic power source and the battery power into AC power to supply the system and the load, or converting the system power into DC power to supply the battery to the battery for use as charging power of the battery. Inverter / rectifier;
A grid connection relay separating the inverter output from the inverter / rectifier and the grid in the event of a power failure of the grid;
A charge-discharge relay that separates the battery charge-discharger from an inverter / rectifier when the system is connected to the solar power source; And
A grid-connected type having an uninterruptible function, comprising a control unit for controlling the solar power generation system and controlling the PV converter, the battery charge-discharge converter, the inverter / rectifier, the grid connection relay, and the charge-discharge relay. Hybrid solar power system. The method of claim 1,
When the photovoltaic power generated by the solar cell is larger than the load of the load, the PV converter is operated in a MPPT control method.
The surplus power of the photovoltaic power remaining after supplying to the load is supplied to the grid, wherein the charge-discharge relay separates the battery charger-discharger from the inverter. Solar power system. The method of claim 1,
When the solar power generated by the solar cell is less than the load of the load, the grid-connected hybrid solar power generation system having an uninterruptible function, characterized in that for supplying the power of the battery to the load. The method of claim 1,
When the battery requires charging, the grid-connected hybrid solar power generation system having an uninterruptible function, characterized in that the solar power generated by the solar cell is decompressed and used first for charging the battery, and the remaining power is supplied to the load. system. The method of claim 1,
When the grid is out of power, the grid connection relay is opened to separate the grid and the inverter / rectifier to supply the solar power to the load, and when the solar power by the solar cell is impossible, the battery power is supplied. System-type hybrid solar power generation system having an uninterruptible function, characterized in that for supplying to the load. The method of claim 1,
When the solar power generation by the solar cell is impossible, the grid-connected hybrid solar power generation system having an uninterruptible function, characterized in that to supply power to the load from the system. The method of claim 1,
When the inverter / rectifier operates as a rectifier, the inverter / rectifier operates as a PFC (Power Factor Correction) rectifier for controlling and controlling the system power factor to rectify the power of the system by direct current to charge the battery. Grid-connected hybrid solar power system with uninterruptible power.

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