KR102555106B1 - Apparatus for controlling power output of distributed generations - Google Patents

Abstract

A distributed power generation output control device is disclosed. Distributed power generation output control device of the present invention includes a three-phase PT (Potential Transformer) installed on the primary side of a linking transformer to measure the primary side voltage of the linking transformer; And a PCS that measures the primary side voltage of the linkage transformer through a three-phase PT, measures the output current of the PCS (Power Conversion System), and controls the generation output according to the linkage transformer's primary side voltage and PCS output current. It is characterized in that it includes.

Description

Distributed power generation output control device {APPARATUS FOR CONTROLLING POWER OUTPUT OF DISTRIBUTED GENERATIONS}

The present invention relates to a distributed power generation output control device, and more particularly, when connected to a distributed power source through the primary side voltage of a linking transformer and the output current of a power conversion system (hereinafter simply referred to as 'PCS'). It relates to a distributed power generation output control device that improves the generation output of a primary side grid connection point (Power Conditioning Control, hereinafter simply referred to as 'PCC') by controlling the generation output of a linkage transformer.

Distributed power generation such as solar power generation and wind power generation uses PCS (Power Conversion System).

The PCS is installed on the secondary side of the linkage transformer, and a watt-hour meter for power reception and an watt-hour meter for power generation are installed in the grid and PCC (Power Conditioning Control).

Existing PCS controls the output based on the secondary side voltage of the linking transformer and the output current of the PCS. Therefore, the maximum sortie of the PCC group was affected by the load in the premises, the power generation load, and the load on the system side.

That is, the PCS measures the secondary side voltage of the linkage transformer and measures the output current of the PCS, and controls the maximum output by comparing the phases of the secondary side voltage and the PCS current.

This PCS is installed in an integrated structure so that the secondary side voltage of the linkage transformer and the output current of the PCS can be measured by connecting only the main bus to the secondary side of the linkage transformer, and the output is controlled for each PCS.

However, since the conventional method controls the output based on the secondary side of the linking transformer of the PCS, due to the phase change of the primary-secondary side of the transformer impedance due to the %Z, X/R ratio, etc. of the linking transformer, the PCC Cannot output maximum power.

The background art of the present invention is disclosed in Korean Patent Registration Publication No. KR 10-2071469 (2020.01.22) 'Power conversion module, and parallel configuration modular power conversion device'.

The present invention has been devised to improve the above problems, and an object according to one aspect of the present invention is to control the power generation output when connected to distributed power through the primary side voltage of the linkage transformer and the output current of the PCS to obtain the power of the PCC stage. It is to provide a distributed power generation output control device that improves generation output.

An apparatus for controlling distributed power generation output according to an aspect of the present invention includes a three-phase PT (Potential Transformer) installed on a primary side of a linkage transformer to measure a primary side voltage of the linkage transformer; And after measuring the primary-side voltage of the linkage transformer through the three-phase PT and measuring the PCS (Power Conversion System) output current, generating output according to the primary-side voltage and the PCS output current of the linkage transformer It is characterized in that it includes a PCS for controlling.

It is characterized in that the wiring method of the three-phase PT of the present invention is the same as that of the linkage transformer.

The wiring method of the three-phase PT of the present invention is characterized in that the phase angle of the second order is Yd1, which is 30 degrees behind the first reference.

The iron core structure of the three-phase PT of the present invention is characterized in that it is the same as the iron core structure of the linkage transformer.

The iron core structure of the three-phase PT of the present invention is characterized in that it is a three-phase iron-resistant iron core structure.

The coil structure of the three-phase PT of the present invention is a three-phase four-wire system in which the primary coil is Y-connected and the primary bushing connects extra-high voltage to A, B, C, and N phases. The coil has a structure in which K and L terminals are drawn for each phase, and the secondary coil is a structure in which tap voltages can be drawn between L-K1, L-K2, and L-K3, and the secondary side of the linkage transformer It is characterized in that it is configured to detect the same voltage as the voltage.

The PCS of the present invention adjusts the magnification of PT (Potential Transformer) and CT (Current Transformer) according to the primary-side voltage of the linkage transformer and the PCS output current, and compares the phases of the measured voltage and current to obtain a comparison result It is characterized in that the generated power is controlled through PWM (Pulse Width Modulation) phase control according to.

Distributed power generation output control device according to an aspect of the present invention improves the generation output of the PCC stage by controlling the generation output when connected to the distributed power source through the primary side voltage of the linking transformer and the output terminal current of the PCS.

1 is a block diagram of a distributed power generation output control device according to an embodiment of the present invention.
2 is a flow chart of a method for controlling distributed power generation output according to an embodiment of the present invention.
3 is a PCS block configuration diagram according to an embodiment of the present invention.
4 is a first-second wiring diagram of a linkage transformer (for power generation) according to an embodiment of the present invention.
5 is a first-secondary connection diagram of a connection transformer (for power reception) according to an embodiment of the present invention.
6 is a diagram showing an iron core coil structure of a three-phase PT according to an embodiment of the present invention.
7 is a diagram showing the structure of primary and secondary coils of a 3-phase PT according to an embodiment of the present invention.
8 is a wiring diagram of a secondary side terminal of a 3-phase PT according to an embodiment of the present invention.
9 is a configuration diagram of an existing 3-phase 300kW photovoltaic facility generation output model.

Hereinafter, an apparatus for controlling distributed power generation output according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or operator. Therefore, definitions of these terms will have to be made based on the content throughout this specification.

1 is a block diagram of a distributed power generation output control device according to an embodiment of the present invention, FIG. 2 is a flow chart of a distributed power generation output control method according to an embodiment of the present invention, and FIG. PCS block configuration diagram according to an embodiment, FIG. 4 is a first-second wiring diagram of a linkage transformer (for power generation) according to an embodiment of the present invention, and FIG. 5 is a linkage diagram according to an embodiment of the present invention It is a first-secondary connection diagram of a transformer (for receiving power), and FIG. 6 is a diagram showing an iron core coil structure of a three-phase PT according to an embodiment of the present invention, and FIG. 7 is a diagram showing a three-phase PT according to an embodiment of the present invention. 8 is a diagram showing the structure of the primary and secondary coils, and FIG. 8 is a connection diagram of secondary side terminals of a 3-phase PT according to an embodiment of the present invention.

Referring to FIG. 1 , an apparatus for controlling distributed power generation output according to an embodiment of the present invention includes a 3-phase Potential Transformer (PT) 31 and a Power Conversion System (PCS) 15.

In FIG. 1, an unexplained numeral 11 denotes a metering device, an unexplained numeral 12 denotes a linkage transformer, an unexplained numeral 13 denotes a power receiving load, and an unexplained numeral 14 denotes a power generation load.

The metering device 11, the linking transformer 12, the receiving load 13, and the generating load 14 are obvious to those skilled in the art, and detailed descriptions thereof are omitted herein.

The three-phase PT 31 is installed on the primary side of the linkage transformer 12 to measure the primary side voltage of the linkage transformer 12 . To this end, the 3-phase PT 31 may be connected to the PCS 15 and the primary voltage detection line 32 of the transformer. Accordingly, the PCS 15 measures the primary voltage of the linkage transformer 12 through the primary voltage detection line 32 of the transformer.

The 3-phase PT (31) changes the secondary side wiring in the same way as the wiring method (Yd1, Yd11, Yy0) of the linkage transformer 12 so that the phases of the primary side and the secondary side of the linkage transformer 12 are the same. . In general, the wiring methods of the connection transformer 12 (Yd1, Yd11, Yy0) may be different depending on the site. Accordingly, in order to match the voltage phases of the primary side and the secondary side of the transformer, the 3-phase PT 31 may be manufactured with the same iron core structure and wiring method as the connection transformer 12 .

Referring to FIG. 2 , in order to control the output of the PCS 15 based on the primary side of the linkage transformer 12, the first and second connections of the linkage transformer 12 are checked (S10).

The wiring method of the 3-phase PT(31) is determined according to the wiring method of the linkage transformer 12, and the secondary side of the 3-phase PT(31)T is connected to the PCS(15) (S20). In this case, the wiring method of the three-phase PT 31 is the same as that of the linkage transformer 12 .

That is, if the primary-secondary wiring method of the linking transformer 12 is Yd1, Yd1 is also applied to the wiring method of the three-phase PT(31)T of the linking transformer 12.

If the first-secondary wiring method of the linking transformer 12 is Yd11, the wiring method of the three-phase PT 31 of the linking transformer 12 also applies Yd11.

If the primary-secondary wiring method of the linking transformer 12 is Yy0, Yy0 is also applied to the wiring method of the three-phase PT 31 of the linking transformer 12.

Next, the PCS 15 detects the primary side voltage of the linkage transformer 12 and measures the output current of the PCS 15 (S30).

PCS (15) adjusts the magnification of PT (Potential Transformer, instrument transformer) and CT (Current Transformer, instrument current transformer) according to the primary side voltage and PCS output current of the connection transformer (12) measured as described above And, after comparing the phase of the primary side voltage of the linkage transformer 12 and the PCS output current, the generated power is controlled through PWM (Pulse Width Modulation) phase control according to the comparison result (S40).

Referring to FIG. 3, the PCS 15 includes a converter that converts power according to the switching operation of six transistors (G1 to G6), an LCL filter that filters power output from the converter, and each transistor of the converter. It may include a converter controller that performs PWM phase control.

Here, the converter controller of the PCS 15 is connected to the primary side of the LCL filter through the current detection line 16, and the three-phase PT of the linkage transformer 12 through the transformer primary voltage detection line 32 ( 31) is connected.

Accordingly, the converter controller converts DC power into AC power by controlling PWM pulses for each of the six transistors using the phase difference between the primary side voltage of the linkage transformer 12 and the PCS output current.

4 shows a Y-Δ connection structure of a power generation transformer in which the primary side has a Y connection and the secondary side has a △ connection structure.

In the Y-Δ connection structure of such a power generation transformer, Yd1 is a wiring method (a) in which the phase angle of the second order is 30 degrees behind the first reference, and the Yd11 connection is the second order phase angle is 30 degrees from the first reference. This is the previous wiring method (b).

5 shows a Δ-Y connection structure of a power receiving transformer in which the primary side has a Δ connection and the secondary side has a Y connection structure.

6 shows the iron core coil structure of the 3-phase PT 31, FIG. 7 shows the structure of the primary and secondary coils of the 3-phase PT 31, and FIG. 8 shows the secondary terminal of the 3-phase PT 31. A connection diagram is shown.

Referring to FIG. 6 , the iron core 71 of the three-phase PT 31 has the same three-phase iron core structure as that of the linkage transformer 12 .

The primary coil 74 is divided into bundles to share the voltage on the extra-high voltage side, and the secondary coil 75 is connected to the inside of the primary coil 74.

In FIG. 6, reference numeral 72 denotes an iron core fixing angle for fixing the iron core, and 73 denotes a fixing bolt for fixing the iron thread fixing angle.

Referring to FIG. 7, the primary and secondary coil structures of the three-phase PT 31 are shown.

The primary coil 74 is Y-connected inside, and the primary bushing 82 is a three-phase, four-wire method so that the A, B, C, and N phases can be connected to the extra high voltage.

The secondary coil has a structure in which K and L terminals are drawn out for each phase.

In addition, the secondary coil 75 has a structure capable of drawing a tap voltage of 110V between L-K1, 220V between L-K2, and 380V between L-K3, and has the same voltage as the secondary voltage of the linkage transformer 12. It is configured to be detectable by this three-phase PT (31).

Reference numeral 83 is a secondary connection terminal, and 84 is a secondary coil tap voltage.

Referring to FIG. 8 , a secondary side terminal connection of a 3-phase PT is shown.

8 (a) is a Yd1 connection diagram, (b) is a Yd11 connection diagram, and (c) is a Yy0 connection diagram.

PT secondary side terminal connection may be Yd1 connection (a), Yd11 connection (86), and Yy0 connection (87) in the same way as the connection method of the linkage transformer 12.

9 is a configuration diagram of an existing 3-phase 300kW photovoltaic facility generation output model.

To compare the generation output, the conventional method and the generation output were compared. In particular, the power generated by the 1st and 2nd order phase angle differences according to the wiring methods (Yd1, Yd11) of the linkage transformer 12 were compared.

As shown in FIG. 9, the distributed power system was modeled with a PV array, a DC-DC converter, and a DC-AC converter. It was analyzed under the conditions of PV Array solar radiation of 1200W/㎡, module temperature of 25℃, and output of 300kW. The DC-DC converter controls the output voltage (VDC2) through MPPT (Maximum Power Point Tracking) control so that the maximum power can be transmitted to the amount of solar radiation of the PV. Through modulation), DC is output as AC voltage through current control.

The power system is composed of a substation and a transformer 12 for linkage. It is configured to measure voltage and current (4V4I) for each phase between modules.

The substation module outputs 45/60MVA, Y-Δ-Y connection, NGR 0.6Ω, and the secondary side voltage is 22.9kV-Y. The transformer module was composed of 300kVA 22.9/0.4kV, and the wiring was composed of Yd1 and Yd11.

Table 1 below is the result of modeling the power generation output of a 300kW photovoltaic facility.

The conventional method is based on the secondary side voltage of the transformer, and this embodiment is modeled by comparing with the primary side voltage standard of the transformer.

According to this embodiment, it can be seen that the power generation efficiency is improved by +2.56% compared to the conventional method. That is, according to the present embodiment, the power generation efficiency can be further improved ((490.636-478.413)/478.413 = 2.5549%) according to the %Z and X/R boiling impedance characteristics of the linkage transformer 12.

division voltage measurement PCS output
(kWh) Transformer wiring
(Y-△ connection) PCC stage output
(kWh) PT Finals comparison conventional way secondary criterion 488.822 Yd1 (30 degrees behind) 478.413 - the present invention
method primary criterion 310.152 Yd11 (30 degrees forward) 285,207 Yd1 PCS malfunction primary criterion 501.670 Yd1 (30 degrees behind) 490.636 Yd1 PT normal connection

As such, the distributed power generation output control device according to an embodiment of the present invention controls the generation output when connected to the distributed power source through the primary side voltage of the linkage transformer 12 and the output terminal current of the PCS, thereby generating the generation output of the PCC stage improve

Implementations described herein may be embodied in, for example, a method or process, an apparatus, a software program, a data stream, or a signal. Even if discussed only in the context of a single form of implementation (eg, discussed only as a method), the implementation of features discussed may also be implemented in other forms (eg, an apparatus or program). The device may be implemented in suitable hardware, software and firmware. The method may be implemented in an apparatus such as a processor, which is generally referred to as a processing device including, for example, a computer, microprocessor, integrated circuit or programmable logic device or the like. Processors also include communication devices such as computers, cell phones, personal digital assistants ("PDAs") and other devices that facilitate communication of information between end-users.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is only exemplary and those skilled in the art can make various modifications and equivalent other embodiments therefrom. will understand Therefore, the true technical protection scope of the present invention will be defined by the claims below.

11: metering device 12: linkage transformer
13: power load 14: power generation load
15: PCS 31: 3-phase PT

Claims (7)

A three-phase PT (Potential Transformer) installed on the primary side of the linkage transformer to measure the primary side voltage of the linkage transformer; and
After measuring the primary-side voltage of the linkage transformer through the three-phase PT and measuring the PCS (Power Conversion System) output current, the generation output is controlled according to the primary-side voltage and the PCS output current of the linkage transformer Including a PCS that
The PCS adjusts the magnification of PT (Potential Transformer) and CT (Current Transformer) according to the primary-side voltage of the linkage transformer and the PCS output current, compares the phase of the measured voltage and current, and generates PWM according to the comparison result. (Pulse Width Modulation) Distributed power generation output control device, characterized in that for controlling the generated power through phase control. A three-phase PT (Potential Transformer) installed on the primary side of the linkage transformer to measure the primary side voltage of the linkage transformer; and
After measuring the primary-side voltage of the linkage transformer through the three-phase PT and measuring the PCS (Power Conversion System) output current, the generation output is controlled according to the primary-side voltage and the PCS output current of the linkage transformer Including a PCS that
Distributed power generation output control device, characterized in that the wiring method of the three-phase PT is the same as the wiring method of the linkage transformer. The method of claim 1, wherein the wiring method of the three-phase PT is
Distributed power generation output control device, characterized in that the phase angle of the second order from the first reference is Yd1 behind by 30 degrees. A three-phase PT (Potential Transformer) installed on the primary side of the linkage transformer to measure the primary side voltage of the linkage transformer; and
After measuring the primary-side voltage of the linkage transformer through the three-phase PT and measuring the PCS (Power Conversion System) output current, the generation output is controlled according to the primary-side voltage and the PCS output current of the linkage transformer Including a PCS that
Distributed power generation output control device, characterized in that the iron core structure of the three-phase PT is the same as the iron core structure of the linkage transformer. The iron core structure of the three-phase PT according to claim 1,
Distributed power generation output control device, characterized in that the three-phase iron core structure. A three-phase PT (Potential Transformer) installed on the primary side of the linkage transformer to measure the primary side voltage of the linkage transformer; and
After measuring the primary-side voltage of the linkage transformer through the three-phase PT and measuring the PCS (Power Conversion System) output current, the generation output is controlled according to the primary-side voltage and the PCS output current of the linkage transformer Including a PCS that
The coil structure of the 3-phase PT is a 3-phase 4-wire system in which the primary coil is Y-connected, the primary bushing connects extra-high voltage to A, B, C, and N phases, and the secondary coil is each It is a structure in which K and L terminals are drawn for each phase, and the secondary coil is a structure that can draw tap voltage between L-K1, L-K2, and L-K3, which is the same as the secondary side voltage of the linkage transformer. Distributed power generation output control device, characterized in that configured to detect the voltage. delete