KR101409272B1 - Power system associated new regeneration energy - Google Patents

Abstract

The present invention discloses a renewable energy-linked power system that stabilizes an alternating-current power supplied from a grid to a load, stably supplies a commercial power of a grid connected with a renewable energy source, and the renewable energy- A grid for supplying commercial power; A renewable energy supply unit including a plurality of renewable energy sources and supplying AC power for stabilizing the commercial power to the grid; A first switch for selectively transmitting the AC power of the grid to the load, a battery for performing charging by the DC power supply and supplying the DC power by the charging power supply, a converter for converting the AC power of the grid into the DC power A bidirectional converter for converting the direct current power into the alternating current power and providing the direct current power to the grid, a power control unit for controlling a conversion operation between the direct current power source and the alternating current power source of the bidirectional converter, AC converter, a second switch which is opposite to the first switch and transmits the AC power of the DC-AC converter selectively to the load, and a second switch which is connected to the stable state of the commercial power supply And controlling the switching of the first and second switches corresponding to the unstable state It characterized by including; load energy supply unit and a switching control unit.

Description

{POWER SYSTEM ASSOCIATED NEW REGENERATION ENERGY}

The present invention relates to a renewable energy-linked power system, and more particularly, to a renewable energy-linked power system that stably supplies commercial power of a grid connected with a renewable energy source and stabilizes an alternating- Power system.

A variety of new and renewable energy is being developed to cope with the depletion of fossil fuels, including renewable energy such as solar, wind, hydropower and intelligence.

The form that uses renewable energy is largely divided into a connected type that supplies power generated by renewable energy to a commercial power source and a stand-alone type that supplies power generated by renewable energy to a load.

Conventional power supplies using renewable energy have a configuration including a DC-AC converter. However, the DC-to-AC converter configured in a typical power supply only supplies power in one direction. Therefore, there has been a problem in that the power generated by using the renewable energy must be supplied to the commercial power source or the load, respectively.

In addition, conventional power supply devices using renewable energy are classified into stand-alone type and connected type, so there is a limit to effectively utilizing new and renewable energy.

In addition, new and renewable energy sources that generate electricity using renewable energy have different production scales (production time, maximum value, minimum value, etc.).

In recent years, if the supply of electricity is blocked or unstable due to the development of the electronics industry, serious social disruption may occur. Therefore, various efforts have been made to maintain a stable power supply in various industrial fields as well as offices.

When an industrial site or an office receives power supplied by a power supply company as well as power using the above-mentioned renewable energy source, the grid is provided with power supplied from a power supply company (for example, KEPCO) Power using renewable energy is supplied at the same time.

Therefore, as the power is supplied from various power sources, there is a problem that the commercial power source of the grid becomes unstable due to the difference in the power type of the power sources including the renewable energy source.

Instability of the commercial power supply of the grid causes problems such as change of reactive power, instantaneous undervoltage (SAG), power factor, and unstable power due to harmonics.

In order to prevent this, the grid is provided with a reactive power compensator for compensating for the change of the reactive power, a power factor compensator for improving the power factor, a SAG compensator for preventing instantaneous undervoltage, and a harmonic compensator for compensating harmonics. However, the above-mentioned configuration has a problem in that an excessive cost is incurred in installing the facilities separately.

According to an aspect of the present invention, there is provided a power supply apparatus for supplying a power of a renewable energy source to a grid on a path for supplying power to the grid, And to provide a renewable energy-linked power system capable of stabilizing the unstable state of the commercial power supply of the grid while efficiently utilizing the renewable energy.

Another object of the present invention is to provide a new and renewable energy-linked power system that can supply power between a load and a grid in both directions, thereby stabilizing a commercial power source by charging and supplying power according to the state of a commercial power source of the grid .

In addition, the present invention provides a bidirectional converter, which can compensate reactive power, SAG, power factor, and harmonics that can be generated as power is supplied from various power sources including renewable energy sources by control of a bidirectional converter, It is another object of the present invention to provide a renewable energy-linked power system capable of stabilizing a commercial power supply of a grid while excluding the use of separate devices for compensating power factor and harmonics.

A renewable energy-linked power system according to the present invention includes: a grid for supplying commercial power; A DC-DC converter for converting a first DC power supplied from an external renewable energy source into a second DC power and providing the converted DC power to the second DC power supply; A first bidirectional converter for converting the second DC power source into an AC power source and providing the same to the grid and converting the AC power source by the commercial power source of the grid into the second DC power source, And a first power source control unit for controlling a conversion operation between the second DC power source and the AC power source of the first bidirectional converter; A first switch for selectively supplying the AC power of the grid to the load, a second battery for charging the third DC power by charging the third DC power, and a second battery for supplying the third DC power by the second charging power, A second bidirectional converter that converts the AC power into the third DC power, converts the third DC power to the AC power and supplies the AC power to the grid, a second bidirectional converter that converts the third DC power into the AC power, And a DC-AC converter for converting the third DC power source to the AC power source, a second power source control unit for controlling the conversion operation of the DC-AC converter to the AC power source, A second switch for selectively transmitting AC power to the load and a second switch for varying the stable state and the unstable state of the commercial power supply And a switching control unit for controlling the switching of the first and second switches by a signal.

Here, when the commercial power supply of the grid is stably supplied, the first power supply control unit of the renewable energy supply unit controls the first bidirectional converter to supply the alternating current power by the commercial power supply of the grid to the first 2 direct-current power source to charge the first battery.

The renewable energy supply unit may further include a generator for generating an AC voltage and an AC-DC converter for converting the AC voltage to the second DC power source, wherein the first battery of the renewable energy supply unit is connected to the DC- DC converter, the AC-DC converter, and the second DC power supply of the first bidirectional converter.

The renewable energy supply unit includes the DC-DC converter that outputs the second DC power by the renewable energy source, and the first battery that outputs the second DC power by the first charging power source Wherein the first power supply control unit selects one or more of the plurality of second DC power supply units having a higher priority among the plurality of second DC power supply units and supplies the AC power to the grid by the first bidirectional converter, As shown in Fig.

The second DC power supply unit may further include a generator for generating an AC voltage and an AC-DC converter for converting the AC voltage into the second DC power.

When the commercial power supply of the grid is unstable and the second direct current power supply by the renewable energy source is not supplied, the first power supply control unit of the renewable energy supply unit controls the bidirectional converter, The second DC power source by the charging power of the battery can be converted into the AC power source and supplied to the grid.

When the commercial power supply is stably supplied from the grid, the switching control unit of the load energy supply unit turns on the first switch under the control of the second power supply control unit to apply the alternating current power of the grid to the load And the second power controller controls the second bidirectional converter to convert the AC power of the grid into the third DC power to charge the battery.

When the commercial power supply of the grid is stably supplied, the switching control unit of the load energy supply unit turns on the second switch under the control of the second power supply control unit, and turns on the alternating- DC converter, the DC-AC converter and the second switch, and charges the second battery by a third DC voltage transmitted from the second bidirectional converter to the DC-DC converter.

When the supply of the commercial power source of the grid is interrupted or unstably supplied, the switching control unit of the load energy supply unit turns on the second switch by the second power source control unit to turn on the second charge of the second battery Wherein the third direct current power by the power source is converted into the alternating current power by the DC-AC converter and supplied to the grid while the third direct current power by the second charging power source of the second battery is supplied from the bidirectional converter It can be converted into an AC power source and supplied to the grid.

The first and second power source control units respectively control the first and second bidirectional converters to perform compensation for reverse current, instantaneous undervoltage (SAG), and harmonics, respectively, and output the outputs of the first and second bidirectional converters Stabilization is preferred.

A renewable energy-linked power system according to the present invention includes: a grid for supplying commercial power; A renewable energy supply unit including a plurality of renewable energy sources and supplying AC power for stabilizing the commercial power to the grid; A first switch for selectively transmitting the AC power of the grid to the load, a battery for performing charging by the DC power supply and supplying the DC power by the charging power supply, a converter for converting the AC power of the grid into the DC power A bidirectional converter for converting the direct current power into the alternating current power and providing the direct current power to the grid, a power control unit for controlling a conversion operation between the direct current power source and the alternating current power source of the bidirectional converter, AC converter, a second switch which is opposite to the first switch and transmits the AC power of the DC-AC converter selectively to the load, and a second switch which is connected to the stable state of the commercial power supply And controlling the switching of the first and second switches corresponding to the unstable state It characterized by including; load energy supply unit and a switching control unit.

Here, when the second switch is turned on by the switching control unit, the load energy supply unit supplies the AC power of the grid to the load through the second bidirectional converter, the DC-AC converter, A first mode in which the AC power is supplied and the battery is charged by the DC power supplied from the bidirectional converter to the DC-DC converter or the DC power supplied by the charging power source of the battery is supplied from the DC- And a second mode in which the direct current power by the charging power supply of the battery is converted from the bidirectional converter to the alternating current power and supplied to the grid is selectively performed .

Therefore, according to the present invention, power is supplied in two directions between a battery on a path for supplying power of a renewable energy source to a grid and a grid on a path for transferring power between the grid and the grid to a load, And it is possible to stabilize the unstable state of the commercial power supply of the grid.

In addition, power can be supplied to the grid in both directions, so that charging and power supply can be performed according to the state of the commercial power supply of the grid, and commercial power supplied to the grid and commercial power supplied to the load can be stabilized.

In addition, according to the present invention, it is possible to compensate the reactive power, SAG, power factor, and harmonics that can be generated due to power supply from various power sources including new and renewable energy sources by controlling the bidirectional converter, .

In addition, according to the present invention, since compensation of reactive power, SAG, power factor, and harmonics of a power source supplied to or supplied to the grid is performed by controlling the bidirectional converter, the cost required for stabilizing the commercial power source is reduced.

1 is a systematic diagram showing a preferred embodiment of a renewable energy linked power system according to the present invention;
FIG. 2 to FIG. 7 are schematic diagrams for explaining the operation of the embodiment according to the state of the commercial power source of the grid. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be understood that the terminology used herein is for the purpose of description and should not be interpreted as limiting the scope of the present invention.

The embodiments described in the present specification and the configurations shown in the drawings are preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention and thus various equivalents and modifications Can be.

A preferred embodiment of the power system for renewable energy according to the present invention includes a grid 130 for supplying commercial power, a renewable energy supply for supplying AC power to the grid 130, And a load energy supply unit for supplying AC power to the AC power source.

Here, the grid 130 supplies AC power to a facility or a building from a power supply company (for example, KEPCO) using commercial power.

The renewable energy supply unit is configured to stably supply alternating current power from the renewable energy source 100 to the grid 130. The embodiment of the present invention is a renewable energy source 100 that can supply solar power, And at least one new-renewable energy generation facility using the intelligence or the like.

The renewable energy supply unit includes a DC-DC converter 110, a bidirectional converter 120, a power control unit 140, a battery 150, an AC-DC converter 160, and a generator 170.

The DC-DC converter 110 converts DC power supplied from an external renewable energy source 100 into a DC power having a specific level for supplying the DC power to a commercial power source, .

The bidirectional converter 120 converts the DC power output from at least one of the DC-DC converter 110, the AC-DC converter 160, and the battery 150 into an AC power and supplies the DC power to the grid 130 And a function of converting AC power from a commercial power source of the grid 130 to DC power and supplying the DC power to the battery 150 for charging. The power conversion of the bidirectional converter 120 is controlled by a power controller 140 .

Here, the bidirectional converter 120 may be configured to incorporate a reactor-integrated transformer to bidirectionally output the AC power to the grid 130 and the DC power to the battery 150, and more specifically, (Not shown) and a reactor core (not shown) at the same time. The bi-directional converter 120 may be one that has been filed by the present applicant as a patent application, and a detailed description thereof will be omitted.

The power control unit 140 controls the output of the bidirectional converter 120 to be stabilized so that the bidirectional converter 120 converts the DC power input from one side to the AC power and outputs the AC power to the other side, The power conversion for converting the AC power to the DC power for supplying the battery 150 is performed in parallel with the power factor, the instantaneous undervoltage (SAG) and the compensation for harmonics.

The battery 150 is charged by a DC power source applied from at least one of the DC-DC converter 110, the bidirectional converter 120, and the AC-DC converter 160 while the DC power is supplied by the charging power source Bidirectional converter 120 as shown in FIG.

The generator 170 includes a facility for generating an AC power by self-generation of oil or the like in response to a non-power state of the grid 130, that is, a power failure state, and the AC-DC converter 160 is supplied from the generator 170 And supplies the converted AC power to the bidirectional converter 120 or the battery 150.

2, the AC power source of the grid 130 is converted into a DC power source through the bidirectional converter 120 to charge the battery 150. In this case, . That is, the bidirectional converter 120 converts AC power of the grid 130 into DC power under the control of the power control unit 140, and charges the battery 150.

At this time, the bidirectional converter 120 compensates the power factor, the instantaneous undervoltage (SAG), and harmonics of the AC power input from the grid 130 by the power controller 140.

3, the DC power generated by the renewable energy source 100 may be applied to the battery 150 as a DC power level-converted by the DC-DC converter 110, and generated by the generator 170 The AC voltage can be converted to DC power by the AC-DC converter 160 and applied. At this time, the surplus power that remains after charging the battery 150 may be converted to AC power through the bidirectional converter 120 and supplied to the grid 130.

4, the DC power generated by the renewable energy source 100 is converted into an AC power through the DC-DC converter 110 and the bidirectional converter 120, as shown in FIG. 4, when the power of the grid 130 is unstable And may be supplied as a commercial power source of the rear grid 130.

4, the AC power generated by the generator 170 is converted to AC power through the AC-DC converter 160 and the bidirectional converter 120, and then is supplied to the grid (not shown) 130 as a commercial power source. The generator 170 may be operated to supply auxiliary power when the power is not supplied from the renewable energy source 100 or when the amount of power is not sufficient.

The battery 150 may be charged in the process of supplying AC power to the grid 130 using the power of the renewable energy source 100 and the generator 170. [

In addition, when power is not supplied from the renewable energy source 100 and the generator 170 and the commercial power of the grid 130 is unstable, the charging power of the battery 150 is outputted as a DC power as shown in FIG. May be converted to alternating-current power via the power supply 120 and then supplied to the grid 130.

4, when the AC power is supplied to the grid 130, the backward current, the instantaneous undervoltage (SAG), and the harmonics are compensated by the control of the bidirectional converter 120 of the power control unit 140, .

4, the power control unit 140 includes a bidirectional converter 120 and a power supply controller 140. The power supply controller 140 includes a plurality of DC power supply units such as a renewable energy source 100, a generator 170, and a battery 150, So that the AC power can be supplied to the grid 130 by selecting one or more of those having a higher priority.

Meanwhile, the embodiment according to the present invention includes a load energy supply unit that supplies AC power from the grid 130 to the load 30, and the load energy supply unit includes a bidirectional converter 10, a DC-AC converter 12, Switches 14 and 16, switches 16 and 18, a power supply control unit 20, and a switching control unit 22.

Here, the switch 18 has a configuration for switching the connection between the grid 130 and the load 30 to selectively transmit the alternating power of the grid 130 to the load 30.

The switch 16 has a configuration for switching the connection between the DC-AC converter 12 and the load 30 and selectively transmitting the AC power output from the DC-AC converter 12 to the load 30.

Here, the switches 16 and 18 are controlled by the switching control section 22, and the switches 16 and 18 are configured to perform an operation in which the on and off states are incompatible with each other.

The bidirectional converter 10 may have the same function as the bidirectional converter 120. The bidirectional converter 10 converts the AC power input from the grid 130 into DC power under the control of the power control unit 20 and supplies the DC power to the DC-AC converter 12 and the battery 14 or to the battery 14 To an alternating current (AC) power, and supplies the alternating current power to the grid 130.

The power controller 20 controls the output of the bidirectional converter 10 to be stabilized so that the bidirectional converter 120 converts the DC power to AC power and supplies the AC power to the grid 130, To the DC power supply for supplying the AC power to the battery 150 and the DC-AC converter 12 in parallel with the compensation for the power factor, the instantaneous undervoltage (SAG) and the harmonics.

The DC-AC converter 12 is configured to convert the DC power supplied from the bidirectional converter 10 and the battery 14 to an AC power source and deliver it to the switch 16.

The battery 14 has a function of charging the DC power output from the bidirectional converter 10 and supplying the DC power from the charging power source to the bidirectional converter 10.

The power control unit 20 detects the commercial power state of the grid 130 that provides the AC power to the bidirectional converter 10 and provides the switching control unit 22 with a control signal corresponding to a stable or unstable state.

The switching control unit 22 has a configuration for controlling the switching of the switches 16 and 18 by a control signal of the power supply control unit 20 which varies in accordance with the stable and unstable states of the commercial power supply.

The load energy supply unit configured as described above performs a function of stably supplying AC power to the load 30 according to the state of the grid 130. [

5, the switching control unit 22 turns on and off the switch 16 and turns on and off the switch 18 according to the control signal of the power control unit 20, So that the alternating current power by the commercial power source of the grid 130 can be transmitted to the load 30 through the switch 18.

At this time, the alternating current power by the commercial power source of the grid 130 can be converted into the direct current power by the bidirectional converter 10 and then charged into the battery 14. [

5, the bidirectional converter 10 can compensate for the reverse current, the instantaneous undervoltage (SAG), and the harmonics of the AC power source under the control of the power source control unit 20. [

6, the switching control unit 22 controls the switch 16 according to the control signal of the power control unit 20, in response to a stable state of the commercial power supply of the grid 130, DC converter 12 and switch 16 to the load 30 by turning on and off the switch 18 by turning on the switch 18 and turning off the switch 18 .

The DC power output from the bidirectional converter 10 is supplied to the battery 14 to charge the battery 14. [

6, the bidirectional converter 10 can compensate the power factor, the instantaneous undervoltage (SAG), and the harmonics of the AC power source under the control of the power source control unit 20. [

7, the switching control unit 22 controls the switch 16 according to the control signal of the power supply control unit 20 in response to the interruption of the supply of the AC power by the commercial power supply of the grid 130 or the unstable AC power supply, And the switch 18 is turned off to convert the DC power from the charging power source of the battery 14 from the DC-AC converter 12 to the AC power and then transfer the AC power to the load 30 via the switch 16 .

The unidirectional AC power of the grid 130 can be stabilized by converting the DC power from the charging power source of the battery 14 into the AC power from the bidirectional converter 10 and supplying it to the grid 130.

7, the bidirectional converter 10 can compensate the power factor, the instantaneous undervoltage (SAG), and the harmonics of the AC power source under the control of the power source control unit 20. [

As described above, according to the present invention, power is supplied in both directions between a battery and a grid on a path for supplying power of a renewable energy source to a grid, and a battery and a grid on a path for transferring power of the grid to a load, It can be utilized efficiently.

In addition, according to the present invention, when the commercial power source of the grid is unstable, the commercial power source can be stabilized by using the charging power source of the battery, and stable power can be supplied to the load.

According to the present invention, the power can be supplied to the grid in both directions, so that the charging of the battery and the power supply to the grid can be performed according to the state of the commercial power supply. As a result, It is possible to stabilize the AC power source.

In addition, the cost of stabilizing the commercial power of the grid can be reduced by compensating reactive power, SAG, power factor, and harmonics that may occur as power is supplied from various power sources including new and renewable energy sources by controlling the bidirectional converter have.

Also, since the compensation of reactive power, SAG, power factor and harmonics of the power supplied to or supplied to the grid is performed by the control of the bidirectional converter, the cost required for stabilizing the commercial power source can be reduced.

10: Bi-directional converter 12: DC-AC converter
14: Battery 16, 18: Switch
20: power supply control unit 22: switching control unit
30: load 100: renewable energy source
110: DC-DC converter 120: Bidirectional converter
130: grid 140: power control unit
150: Battery 160: AC-DC converter
170: generator

Claims (15)

delete delete delete A grid for supplying commercial power;
A DC-DC converter for converting a first DC power supplied from an external renewable energy source into a second DC power and providing the converted DC power to the second DC power supply; A first bidirectional converter for converting the second DC power source into an AC power source and providing the same to the grid and converting the AC power source by the commercial power source of the grid into the second DC power source, And a first power source control unit for controlling a conversion operation between the second DC power source and the AC power source of the first bidirectional converter; And
A first switch for selectively supplying the AC power of the grid to the load, a second battery for supplying the third DC power by the third DC power source and the second DC power by the second DC power source, A second bidirectional converter for converting the AC power into the third DC power, converting the third DC power to the AC power and providing the AC power to the grid, a second bidirectional converter of the second bidirectional converter, A second power source control unit for controlling the converting operation between the AC power source and the AC power source, a DC-AC converter for converting the third DC power source to the AC power source, A second switch for selectively delivering power to the load and a control switch for varying a stable state and an unstable state of the commercial power supply, Energy supply by the load and a switching control unit for controlling the switching of the first and second switches; includes,
Wherein the renewable energy supply unit includes a DC-DC converter for outputting the second DC power by the renewable energy source, a plurality of first DC power sources for outputting the second DC power by the first charging power source Wherein the first power supply control unit selects one or more of the plurality of second DC power supply units having a higher priority and supplies the AC power to the grid by the first bidirectional converter Renewable energy-linked power system.
5. The method of claim 4,
Wherein the second DC power supply means further comprises a generator for generating an AC voltage and an AC-DC converter for converting the AC voltage into the second DC power.
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