KR20230054058A - reactive power control type power conversion apparatus - Google Patents

Abstract

The present invention relates to a reactive power control type power converter, and relates to an inverter that converts electricity supplied from an alternative power supply unit that supplies alternative power from a renewable energy generator into alternating current and supplies power to a grid, an alternative power supply unit, and a grid A charging power supply unit that stores electrical energy supplied from at least one of the current detector unit that detects current supplied to the grid through an inverter, and power factor information and active power and reactive power requirements are communicated from the grid connected to a load consuming power. and controls the voltage, current, and phase angle between the voltage and current output through the inverter to meet the power factor information received from the grid, active power, and reactive power demand, and the current detected from the current detection unit determines the reference current. and a power control unit that determines whether or not the current detected by the current detection unit exceeds the reference current by changing the pulse width of the inverter to control the current to be less than or equal to the reference current. According to this reactive power control support type power converter, it is possible to compensate for the reactive power on the consumer demand side while supporting the supply of alternative power generated and generated through renewable energy sources to the power system, thereby reducing the power supply of the power system. It supports efficient operation and provides the advantage of improving stability by being managed to be limited within the rated current.

Description

Reactive power control support type power converter {reactive power control type power conversion apparatus}

The present invention relates to a reactive power control support type power conversion device, and more particularly, to a reactive power control support type power conversion device supporting reactive power supply in accordance with a power factor required for a load connected to a grid supplying commercial power. it's about the device

In general, power actually consumed by the load is referred to as effective power, and power that cannot be effectively used by the load is referred to as reactive power. Since reactive power is not effectively used by the load and only reciprocates between the power source and the load, the power supply system must increase its capacity beyond a certain amount of power required by the load.

In addition, in order to solve or reduce losses and disadvantages caused by an increase in reactive power, a reactive power compensator that compensates for reactive power exchanged between an AC voltage source and a line using a capacitor connected to an AC voltage source in the vicinity of a transformer is used. , Korean Patent Registration No. 10-0791625, etc. are variously disclosed.

On the other hand, due to the emergence of environmental problems worldwide, the use of distributed power sources including new and renewable energy is increasing, and technology development related to new and renewable energy is also being actively conducted.

Therefore, in order to efficiently use the power generated from the main power supply source, which is the main power supply source, it is possible to connect a renewable energy source to the power system, and in this case, to properly convert the power in consideration of the state of the consuming load, the battery A charging device such as At this time, if the renewable energy supplies only active power, if the capacity of the main power supply source is small or if the renewable energy source is larger than the main power supply source, reactive power compensation is not properly performed, increasing the instability of the power system. .

Therefore, when supplying renewable energy to the power system, a structure capable of efficiently managing the power system operated by the periodic power supply source or the main power supply source by compensating for the reactive power is required.

In addition, when a short-circuit/ground fault occurs in a substation connected to the grid supplying commercial power or a nearby substation, excessive current flows through the inverter and may cause damage to power electronic devices. To prevent this, a method of separating distributed power from the power system In case of system failure, a structure capable of controlling the inverter current to be limited within the rated current is required.

The present invention was invented to solve the above requirements, and a reactive power control support type power converter that can compensate for reactive power when supplying power generated from renewable energy to a power system that supplies commercial power is provided. Its purpose is to provide

In order to achieve the above object, a reactive power control support type power converter according to the present invention includes an alternative power supply unit for supplying alternative power from a renewable energy generator that generates power by generating power from a renewable energy source; an inverter that converts the electricity supplied from the alternative power supply unit into alternating current and supplies power to a grid that supplies commercial power or converts the power supplied from the grid into direct current; a charging power supply unit for storing electrical energy supplied from at least one of the alternative power supply unit and the grid and supplying the stored electrical energy through the inverter; a current detector detecting a current supplied to the grid through the inverter; and receiving power factor information, active power, and reactive power requirements from the grid connected to a load consuming power through communication, and outputting the power factor information, active power, and reactive power requirements through the inverter in accordance with the received power factor information and the active power and reactive power requirements received from the grid. Controls the voltage, current and phase angle between the voltage and the current, determines whether the current detected from the current detection unit exceeds the reference current, and determines that the current detected from the current detection unit exceeds the reference current and a power control unit controlling the pulse width of the inverter to be equal to or less than the reference current.

Preferably, the power control unit controls the output current by changing a pulse width such that a width of a zero potential region of the inverter is increased when it is determined that the current detected by the current detection unit exceeds the reference current.

In addition, a charging and discharging processing unit controlled by the power control unit controls charging to the charging power supply unit or output to the inverter of the power charged in the charging power supply unit; It includes at least one of a photovoltaic generator generating electricity by receiving light and a wind turbine generating power from blades rotated by wind.

According to the reactive power control support type power conversion device according to the present invention, it is possible to compensate for the reactive power on the consumer demand side while supporting the supply of alternative power generated and generated through a new and renewable energy source to the power system. It supports the efficient operation of the power supply and provides the advantage of improving stability by managing it to be limited within the rated current.

1 is a diagram showing a reactive power control support type power converter according to the present invention;
2 is a blow diagram showing an inverter control process of the power controller of FIG. 1;

Hereinafter, a reactive power control support type power converter according to a preferred embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a diagram showing a reactive power control support type power converter according to the present invention.

Referring to FIG. 1, the reactive power control support type power converter 100 according to the present invention includes an alternative power supply unit 110, an inverter 120, a rectification filter 125, a main transformer 127, a charge/discharge processor ( 131), a charging power supply unit 135, a voltage detection unit 141, a current detection unit 143, a power control unit 170, and an operation center 180.

The alternative power supply unit 110 supplies alternative power from a renewable energy generator that generates power by generating power from a renewable energy source. In the illustrated example, the renewable energy generator of the alternative power supply unit 110 generates power by receiving the wind power generator 101 and the incident sunlight, generating power from blades rotated by the wind, and a plurality of solar cells array A photovoltaic generator 103 is illustrated. It goes without saying that a geothermal generator using geothermal heat, a tidal power generator that generates power by tidal power, and the like can be applied to the renewable energy generating device in addition to those exemplified.

The converter 105 converts the AC power output from the wind power generator 101 into DC power and outputs it.

Although not shown, a DC-DC converter for converting the generated DC power into a target DC voltage may be further applied to the alternative power supply unit 110, of course.

In addition, it can be built to detect the voltage and current for the alternative power generated from the alternative power supply unit 110 and provide it to the power control unit 170 to be described later.

The inverter 120 converts electricity supplied from the alternative power supply unit 110 or DC electricity supplied from the charging power supply unit 135 to be described later into alternating current and supplies power to the grid 190 that supplies commercial power or the grid 190 It can be controlled by the power control unit 170 to convert the power supplied from ) into direct current and supply it to the charging power supply unit 135 . The inverter 120 may be configured to convert single-phase or three-phase alternating current by turning on/off switching devices corresponding to driving pulses.

The rectifying filter 125 removes harmonic noise included in the voltage output from the inverter 120 and rectifies it into a sine wave, and includes an inductor.

The main voltage generator 127 is applied to adjust the voltage according to the primary and secondary winding ratios according to the grid 190 supplying commercial power, and can be omitted, of course.

The charge/discharge processing unit 131 is controlled by the power control unit 170 to charge the charging power unit 135 or to control the output so that the power charged in the charging power unit 135 is discharged to the inverter 120 .

The charging power supply unit 135 stores electrical energy supplied from at least one of the alternative power supply unit 110 and the grid 190, and supplies the stored electrical energy through the inverter 120. The charging power supply unit 135 is constructed with a plurality of batteries.

The voltage detector 141 measures the output voltage supplied from the inverter 120 to the grid 190 and provides it to the power controller 170 .

The current detection unit 143 detects the current supplied to the grid 190 through the inverter 120 and, in the illustrated example, detects the current output through the rectifying filter 125 and provides it to the power controller 170.

The power control unit 170 receives power factor information, active power, and reactive power demand from the grid 190 connected to the load 10 through communication, and transmits the received power factor information, active power, and reactive power demand from the grid 190. The voltage, current, and phase angle between the voltage and current output through the inverter 120 are controlled to match.

Here, the power control unit 170 is configured to perform communication with the operation center 180 that checks the state of the load 10 and provides power factor information, active power, and reactive power demand.

As an example, when the power converter 100 supplies only reactive power, the power controller 170 controls the phase difference between the voltage and the current output from the inverter 120 to be 90 degrees according to the power factor command.

The power control unit 170 can stably support power supply to the power system of the grid 190 that supplies commercial power with the alternative power generated from the renewable energy generator that generates power from renewable energy sources. It receives information on active power and reactive power from the grid and consumer demand side of the power system and compensates for active power as well as reactive power to support more efficient management of power in the power system.

In addition, the power control unit 170 determines whether the current detected by the current detection unit 143 exceeds the reference current, and if it is determined that the current detected by the current detection unit 143 exceeds the reference current, the inverter 120 The pulse width is changed and controlled to be less than the reference current.

A current control process of the inverter 120 by the power control unit 170 will be described with reference to FIG. 2 .

The power controller 170 measures the output current of the inverter 120 provided to the current detector 143 (step 210).

Next, it is determined whether the measured inverter current exceeds the reference current (step 220).

In step 220, if the inverter current is less than or equal to the reference current, it is determined to maintain the normal pulse.

Alternatively, if it is determined that the inverter current exceeds the reference current, the pulse width for driving the inverter 120 is changed to suppress the overcurrent (step 240). Here, the power controller 170 changes the pulse width so that the width of the zero potential region of the inverter 120 increases when it is determined that the current detected by the current detector 143 exceeds the reference current.

Then, the inverter is driven with the determined pulse width (step 250).

Under the control of the power control unit 170, the current of the inverter 120 is kept below the rated value to prevent burnout of the switching element of the inverter 120 and to separate it from the grid 190 that supplies commercial power. It can also improve the voltage stability of the power system.

According to the reactive power control support type power conversion device described above, it is possible to compensate for the reactive power on the consumer demand side while supporting the supply of alternative power generated and generated through renewable energy sources to the power system. It supports the efficient operation of the power supply and provides the advantage of improving stability by managing it to be limited within the rated current.

110: alternative power supply unit 120: inverter
125: rectification filter 131: charge and discharge processing unit
135: charging power supply unit 141: voltage detection unit
143: current detection unit 170: power control unit
180: operation center

Claims (3)

In the reactive power control type power converter,
An alternative power supply unit for supplying alternative power from a renewable energy generator generating power by generating power from a renewable energy source;
an inverter that converts the electricity supplied from the alternative power supply unit into alternating current and supplies power to a grid that supplies commercial power or converts the power supplied from the grid into direct current;
a charging power supply unit for storing electrical energy supplied from at least one of the alternative power supply unit and the grid and supplying the stored electrical energy through the inverter;
a current detector detecting a current supplied to the grid through the inverter; and
Receive power factor information, active power, and reactive power requirements from the grid connected to a load consuming power through communication, and output through the inverter to meet the power factor information, active power, and reactive power requirements received from the grid Control voltage, current, and phase angle between the voltage and the current, determine whether the current detected from the current detection unit exceeds the reference current, and if it is determined that the current detected from the current detection unit exceeds the reference current, the Reactive power control support type power conversion device comprising a; power control unit that changes the pulse width of the inverter and controls the current to be equal to or less than the reference current. The method of claim 1, wherein the power control unit controls the output current by changing a pulse width so that a width of a zero potential region of the inverter is increased when it is determined that the current detected by the current detection unit exceeds the reference current. Reactive power control support type power converter. The method of claim 1, further comprising: a charge/discharge processing unit controlled by the power control unit to control charging of the charging power unit or output of power charged to the charging power unit to the inverter;
The renewable energy generating device comprises at least one of a photovoltaic generator generating power by receiving incident sunlight and a wind power generator generating electric power from blades rotated by the wind, characterized in that it includes reactive power control support type power inverter.

Images