KR20150006956A - Power quality conditioner - Google Patents

Abstract

The present invention relates to an apparatus for compensating power quality, and more particularly, to an apparatus for compensating power quality, which controls series inverter connection by using a semiconductor rectifying device. According to the present invention, the apparatus for compensating the power quality, which compensates quality of a power supplied from a system to provide the compensated quality to a load, comprises: a detection unit which detects voltage fluctuation of the system; a switch unit which is turned on or off; a voltage compensation unit which is connected to the system according to an operation of the switch part and compensates the voltage fluctuation of the system when the voltage compensation unit is connected to the system; and a control unit which controls the operation of the switch unit according to whether the voltage fluctuation of the system, which is transmitted from the detection unit, is detected and controls an operation of the voltage compensation unit according to the operation of the switch unit.

Description

[0001] POWER QUALITY CONDITIONER [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power quality compensating apparatus, and more particularly, to a power quality compensating apparatus for controlling a series inverter connection using a semiconductor rectifying element.

Recently, there has been a problem of deterioration of power quality due to the use of non-linear loads due to industrialization. The power quality deterioration is caused by the problem of current such as harmonic current inflow and power factor reduction and voltage problems such as instant interruption, .

The influx of harmonic current into the grid due to nonlinear load causes problems such as distortion of power supply voltage, increase of capacity of generator or transmission line transformer, generation of heat and resonance of other power devices in the grid, . To solve this problem, active power filters are being studied.

On the other hand, a dynamic voltage compensator is being studied to solve the problem of malfunction or failure of power equipment due to unbalance of power supply voltage, voltage drop, and voltage increase.

The UPQC (Unified Power Quality Conditioner) includes a series inverter and a shunt inverter, so that the active power filter function and the dynamic voltage compensator function can be performed at the same time.

1 is a block diagram of a general multi-function power quality compensation apparatus.

Referring to Fig. 1, the multi-function power quality compensating apparatus includes a series inverter 10 for compensating for voltage fluctuation and a parallel inverter 20 for compensating harmonic current. The parallel inverter 20 may be connected in parallel with the input and the output, and the series inverter 10 may be connected in series with the input, which means a grid, And the parallel inverter 20 may be connected to the battery 30 at one end thereof.

However, since the multifunctional power quality compensating device always starts up the series inverter and the parallel inverter, there is a problem that unnecessary power is wasted.

The present invention provides a power quality compensation apparatus for controlling whether or not a serial inverter is connected between a system and a load using a semiconductor rectifying device.

The apparatus for compensating power quality according to an embodiment of the present invention compensates for the quality of power supplied from a system and provides the load to a load. The apparatus includes a sensing unit for sensing a voltage variation of the system, A voltage compensating unit connected to the system in response to the operation of the switch unit and compensating for a voltage variation of the system when the switch is connected to the system, And a control unit for controlling the operation of the voltage compensating unit according to the operation of the switch unit.

According to the present invention, more efficient power quality compensation can be performed by connecting the series inverter only when the dynamic voltage compensation is required.

1 is a block diagram of a general multi-function power quality compensation apparatus.
2 is a block diagram of a power quality compensation apparatus according to an embodiment of the present invention.
3 is a three-phase circuit diagram for explaining a series inverter drive method of the power quality compensation apparatus according to the embodiment of the present invention.
4 is a circuit diagram of a power quality compensating apparatus including a semiconductor rectifying device according to an embodiment of the present invention.
5 is a circuit diagram of a power quality compensating apparatus including a semiconductor rectifying device according to another embodiment of the present invention.
6 is a flowchart illustrating a method of driving a power quality compensation apparatus according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the width, length, thickness, and the like of the components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

2 is a block diagram of a power quality compensation apparatus according to an embodiment of the present invention.

2, a power quality compensating apparatus 100 according to an exemplary embodiment of the present invention includes a sensing unit 110, a controller 130, a switch unit 150, a voltage compensating unit 170, a current compensating unit 190 ).

The sensing unit 110 senses the instantaneous voltage drop or the instantaneous voltage rise of the system 10. For example, when the voltage compensating unit 170 is inactivated, the sensing unit 110 may sense the instantaneous voltage drop or the instantaneous voltage rise of the system 10. [ On the other hand, when the voltage compensating unit 170 is activated, the sensing unit 110 can sense whether or not the rated voltage is supplied from the system 10.

The control unit 130 controls the operation of the sensing unit 110, the switch unit 150, the voltage compensating unit 170 and the like included in the power quality compensating apparatus 100 as a whole.

The control unit 130 controls the operation of the switch unit 150 according to whether the instantaneous voltage drop or the instantaneous voltage rise of the sensing unit 110 is detected.

For example, when the instantaneous voltage drop or the instantaneous voltage rise is not detected at the sensing unit 110, the controller 130 may control the switch unit 150 to be turned on. On the other hand, when the instantaneous voltage drop or the instantaneous voltage rise is sensed by the sensing unit 110, the switch unit 150 is controlled to be OFF, and when the voltage compensating unit 170 detects the voltage drop Can be compensated for.

The switch unit 150 may operate on or off according to the control signal transmitted from the control unit 130. [ The switch unit 150 can determine whether the system 10, the load 20, and the voltage compensating unit 170 are connected in series.

The voltage compensating unit 170 is connected in series with the system 10 and the load 20 only when an instantaneous voltage drop or an instantaneous voltage rise occurs to compensate for the voltage drop which is lowered or increased. For example, the voltage compensating unit 170 can compensate the lowered voltage or the increased voltage according to the control signal transmitted from the control unit 130 only when the switch unit 150 is off.

The voltage compensating unit 170 may be connected to the battery 30 for voltage compensation.

The current compensating unit 190 includes a function of an active power filter that compensates harmonic current flowing from the system 10 under the control of the controller 130 and a function of a static reactive power compensator STATCOM, Static Compensator) function and a function of Uninterruptible Power Supply (UPS) when system 10 fails.

The current compensating unit 190 may selectively perform an active power filter or a static reactive power compensator function and perform the uninterruptible power supply function only when the system 10 fails.

3 is a three-phase circuit diagram for explaining a series inverter drive method of the power quality compensation apparatus according to the embodiment of the present invention.

Referring to FIG. 3, a system 10 providing a three-phase power source and a load 20 formed in three phases may be connected for substantial power supply. At this time, the load 20 can receive power corresponding to the phase voltage magnitude between any one of the R phase, the S phase, and the T phase, and the neutral line N from the system 10. For example, the phase voltage magnitude is typically 380V.

However, the system 10 may provide an instantaneous drop or elevated voltage depending on the situation. At this time, the power quality compensation apparatus 100 may be connected between the system 10 and the load 20 so that the load 20 is always supplied with a constant voltage.

The voltage compensating unit 170 included in the power quality compensating apparatus 100 according to the embodiment of the present invention includes a series inverter unit 171, a series inverter unit 171, a three-phase inductor connected in series with the switch unit 150, And a three-phase capacitor connected in parallel with the series inverter unit 171 and the switch unit 150. [

The voltage compensating unit 170 is connected in series with the coupling transformer 140 through the switch unit 150. [

The voltage compensating unit 170 can compensate for the instantaneous drop or the increased voltage by using the voltage of the battery 30 when the switch unit 150 is turned off under the control of the controller 130. [

Under the control of the control unit 130, the switch unit 150 operates normally in an ON state and may operate in an OFF state only when an instantaneous voltage drop or an instantaneous voltage rise occurs. For example, the switch unit 150 may be formed by connecting two silicon controlled rectifiers (SCRs) such as a thyristor in parallel in the opposite direction.

When the magnitude of the phase voltage provided from the system 10 is maintained at 380 V, the control unit 130 turns on the switch unit 150, for example.

The switch unit 150 that operates in the ON state can operate such that the current flowing from the system 10 to the load 20 does not flow to the voltage compensating unit 170. [ For example, when the switch unit 150 is turned on, the current supplied from the system 10 can flow in the direction of the load 20 through the two semiconductor rectifying elements one after another.

On the other hand, when an instantaneous voltage drop occurs, the control unit 130 turns off the switch unit 150, for example, when the magnitude of the phase voltage provided from the system 10 is detected as 350V.

The switch unit 150 that operates in the off state can operate so that a current flowing from the system 10 toward the load 20 flows to the voltage compensating unit 170. [ For example, when the switch unit 150 is turned off, the current supplied from the system 10 can flow to the series inverter unit 171 without passing through the two semiconductor rectifying elements.

The series inverter unit 171 can provide a + 30V compensation voltage across the coupling transformer unit 140 using the battery 30 when the phase voltage provided from the system 10 is 350V.

Alternatively, when an instantaneous voltage rise occurs, the control unit 130 turns off the switch unit 150 when the magnitude of the phase voltage provided from the system 10 is detected as 410 V, for example.

The series inverter unit 171 can provide a compensation voltage of -30 V across the coupling transformer unit 140 using the battery 30 when the phase voltage provided from the system 10 is 410 V. [

Thus, the load 20 can always be supplied with a constant voltage by compensating for the voltage fluctuation caused by the instantaneous voltage drop or the instantaneous voltage rise by the series inverter unit 171. [

4 is a circuit diagram of a power quality compensating apparatus including a semiconductor rectifying device according to an embodiment of the present invention.

Referring to Figure 4, the system 10 and the load 20 include a circuit breaker 11, a magnetic contector 40, a load breaker 21, a battery 30, The load sensing unit 113, the system load switch unit 120, the series inverter coupling transformer unit 140, the series inverter switch unit 150, the series inverter switch unit 150, The power quality compensating apparatus 100 including the inverter unit 171, the parallel inverter unit 191, the parallel inverter inverter unit 193 and the parallel inverter electromagnetic contactor 195, do. Hereinafter, the circuit components shown in FIGS. 4 and 5 show elements necessary for explaining the operation of the power quality compensating apparatus 100 according to the embodiment of the present invention, and the present invention is not limited thereto.

One end of each of the system breaker 11, the load breaker 21 and the battery breaker 31 is connected to the system 10, the load 20 and the battery 30 and is connected to the system breaker 11, the load breaker 21, And the battery breaker 31 may be connected to the power quality compensation device 100. [

More specifically, one end of the system breaker 11 is connected to the system 10 and the other end is connected to the series inverter-coupled transformer unit 140. The system breaker 11 may perform an overcurrent trip function to prevent the load 20 from malfunctioning due to abnormalities of the system 10. The system breaker 11 may cut off the connection between the load 20 and the system 10,

The system detecting unit 111 is connected at one end to the system breaker 11 and at the other end to the series inverter coupling transformer unit 140 to detect whether the voltage or current supplied from the system 10 is abnormal . The system sensing unit 111 may include at least one sensor and may transmit an abnormal signal to the control unit 130 when an abnormality in voltage or current is detected.

The series inverter coupling transformer unit 140 may be connected in series between the system 10 and the load 20.

One end of the series inverter switch unit 150 is connected to the series inverter coupling transformer unit 140 and the other end is connected to the series inverter unit 171. As described above, the serial inverter switch unit 150 can be operated on or off under the control of the controller 130. [ The serial inverter switch unit 150 may receive the control signal transmitted from the controller 130 through the gate terminal.

One end of the series inverter unit 171 is connected to the series inverter switch unit 150, and the other end thereof is connected to the battery 30. The series inverter unit 171 can supply the voltage supplied from the battery 30 to the series inverter coupling transformer unit 140 according to the operation of the series inverter switch unit 150 under the control of the controller 130. [

The current compensating unit 190 includes a parallel inverter unit 191, a parallel inverter inverter transformer unit 193 and a parallel inverter electromagnetic contactor 195 connected in series. One end of the current compensator 190 is connected to the battery 30 And the other end is connected in parallel between the system (10) and the load (20).

More specifically, the parallel inverter inverter transformer unit 193 is connected in parallel between the series inverter inverter transformer unit 140 and the load 20 via one end of the parallel inverter electromagnetic contactor 195, (191).

The parallel inverter unit 191 can be operated at all times under the control of the controller 130. The parallel inverter unit 191 compensates for the phase of the current with respect to the voltage supplied from the system 10, thereby preventing the system 10 from failing. Or the parallel inverter unit 191 may compensate the reactive power of the load 20. [ At this time, the controller 130 may control the parallel inverter unit 191 to operate either the phase compensation function or the reactive power compensation function.

When the connection between the system 10 and the load 20 is shut down, the control unit 130 uses the parallel inverter unit 191 to supply power from the battery 30 to the load 20 It can be supplied temporarily. In this way, when the load 20 can not receive power from the system 10, the parallel inverter unit 191 can operate as an uninterruptible power supply.

The system load switch unit 120 is connected in series between the system 10 and the load 20 and connects or disconnects the system 10 and the load 20 according to an on or off operation. The system load switch unit 120 can operate on or off when a predetermined condition is satisfied, for example, when the system 10 is shut down. The control unit 130 controls the inter-system load switch unit 120 to operate on when the system 10 is shut down so as to shut off the power supply from the system 10, The supply can be started.

The switch between the system loads 120 may be constituted by a semiconductor rectifying element (SCR). The inter-system load switch unit 120 composed of the semiconductor rectification element (SCR) has high speed and high operation efficiency.

The load sensing unit 113 may be connected at one end to the load breaker 21 and at the other end to the inter-system load switch unit 120 to detect whether the voltage or current supplied to the load 20 is abnormal . The load sensing unit 113 may include one or more sensors, and may transmit an abnormal signal to the controller 130 when an abnormality in voltage or current is detected.

One end of the load breaker 21 is connected to the load 20, and the other end is connected to the inter-system load switch part 120. The load circuit breaker 21 may perform an overcurrent trip function to prevent the system 10 from being disconnected from the load 20 in order to prevent the system 10 from malfunctioning due to the failure of the load 20. [

One end of the battery breaker 31 is connected to the battery 30 and the other end is connected to each of the series inverter 171 and the parallel inverter 191 so that the power quality compensating apparatus 100 fails due to the battery 30 The connection between the power quality compensation apparatus 100 and the battery 30 may be cut off. For example, when a battery 30 supplying a voltage of 150 V is connected to the power quality compensating apparatus 100 having a rated voltage of 100 V, the battery circuit breaker 31 disconnects the power quality compensating apparatus 100 from the battery 30 You can block the connection.

The system load-to-system electromagnetic contactor 40 determines whether the system 10 and the load 20 are connected to the power quality compensation apparatus 100. Further, the system load-on-magnetic contactor 40 can operate on or off according to user input. For example, in the event of a failure of the power quality compensating apparatus 100, the user 20 may be able to receive power from the system 10 without the power quality compensating apparatus 100 while the power quality compensating apparatus 100 is being repaired, Depending on the input, the electromagnetic contactor 40 between the system loads can operate on.

The dotted line connecting the system 10, the series inverter coupling transformer unit 140, the system load switch unit 120, the parallel inverter unit 191, the battery 30 and the load 20 shown in Fig. The operation of the power quality compensating apparatus 100 in a normal case in which a voltage drop or an instantaneous voltage rise does not occur.

In the normal case, the power quality compensating apparatus 100 according to the embodiment of the present invention can compensate the phase of the current to voltage ratio through the parallel inverter 191. At this time, the power quality compensating apparatus 100 can prevent the operation of the serial inverter unit 171 by controlling the series inverter switch unit 150 to operate on.

In this manner, in the normal case, the energy consumed in the power quality compensating apparatus 100 can be reduced by controlling the series inverter unit 171 not to operate. Next, the operation of the power quality compensating apparatus 100 when an instantaneous voltage drop or an instantaneous voltage rise occurs will be described with reference to FIG.

5 is a circuit diagram of a power quality compensating apparatus including a semiconductor rectifying device according to another embodiment of the present invention.

The system 10 shown in FIG. 5, the series inverter coupling transformer unit 140, the system load switch unit 120, the parallel inverter unit 191, the serial inverter unit 171, the battery 30, and the load 20 ) Represents the operation of the power quality compensating apparatus 100 when an instantaneous voltage drop or an instantaneous voltage rise occurs.

5, when the instantaneous voltage drop or the instantaneous voltage rise occurs, the power quality compensating apparatus 100 according to the embodiment of the present invention can compensate the phase of the current to voltage ratio through the parallel inverter 191 In addition, the voltage fluctuation can be compensated through the series inverter 191. At this time, the power quality compensating apparatus 100 can start the operation of the serial inverter unit 171 by controlling the series inverter switch unit 150 to operate in the OFF state.

6 is a flowchart illustrating a method of driving a power quality compensation apparatus according to an embodiment of the present invention.

Referring to FIG. 6, the controller 130 controls the switch unit 150 of the power quality compensating apparatus 100 connected between the system 10 and the load 20 to operate on (S101).

When the controller 130 senses the instantaneous voltage drop of the power supplied from the system 10 through the sensing unit 110 in step S103 and the switch unit 150 of the power quality compensating apparatus 100 is turned off (S105). Although not shown in the drawing, the controller 130 operates in the same manner as when the instantaneous voltage drop of the power supplied from the system 10 is sensed even when the instantaneous voltage increase of the power supplied from the system 10 is detected.

When the switch unit 150 is turned off, a series inverter connected in series between the system 10 and the load 20 operates (S107). The series inverter is included in the voltage compensating unit 170 and can receive power from the battery 30 and compensate for the voltage changed by the supplied power.

When the rated voltage is sensed from the power supplied from the system 10 through the sensing unit 110 in operation S109, the controller 130 turns on the switch unit 150 of the power quality compensating apparatus 100 (S101). Therefore, the controller 130 can compensate the fluctuated voltage by connecting the series inverter only when the voltage drop or the voltage rise occurs, thereby more effectively compensating the power quality.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims and the claims.

10: System
20: Load
100: Power quality compensation device
110:
130:
150:
170:
30: Battery

Claims (7)

1. A power quality compensation apparatus for compensating for a quality of power supplied from a system and providing the same to a load,
A sensing unit for sensing a voltage variation of the system;
A switch unit operated on or off;
A voltage compensating unit connected to the system according to an operation of the switch unit and compensating for a voltage variation of the system when the system is connected to the system; And
And a control unit for controlling the operation of the switch unit according to whether or not the voltage variation of the system is detected by the sensing unit and controlling the operation of the voltage compensating unit according to the operation of the switch unit
Power quality compensation device. The method according to claim 1,
The control unit
Wherein the control unit controls the switch unit to be turned on so that the voltage compensating unit is not connected to the system if the voltage variation of the system is not detected by the sensing unit, and when the voltage variation of the system is sensed by the sensing unit, And controls the voltage compensating unit to be connected to the system
Power quality compensation device. The method according to claim 1,
The switch unit
And a plurality of thyristors connected in parallel to each other in the opposite direction
Power quality compensation device. The method according to claim 1,
The voltage compensating unit
And a series inverter connected in series between the system and the load
Power quality compensation device. The method according to claim 1,
Wherein the voltage compensating unit compensates the voltage fluctuation of the system using an external battery and compensates the positive voltage to the system from the external battery when the voltage fluctuation is an instantaneous voltage drop, The negative voltage to the system is compensated from the external battery
Power quality compensation device. The method according to claim 1,
And a current compensator including a parallel inverter connected between the system and the load, the parallel inverter compensating for a current phase relative to the voltage of the power transmitted from the system and transmitting the compensated current to the load
Power quality compensation device. The method according to claim 6,
When the system is out of order, the current compensating unit operates as an uninterruptible power supply
Power quality compensation device.

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