KR20210044561A - Apparatus and Method for converting power intelligently - Google Patents

Abstract

Disclosed is an intelligent power conversion device which can be linked to an output side of an existing transformer and can maintain a voltage by power conversion of a pulse width modulation (PWM) method. The intelligent power conversion device comprises: a unit power conversion unit having a plurality of unit modules individually selectively configured, and converting power; and a main control unit controlling the unit power conversion unit, and connected or disconnected by a detachable method with the unit power conversion unit.

Description

Apparatus and Method for converting power intelligently

The present invention relates to a distribution transformer technology, and more particularly, to an intelligent power conversion device and method that can be linked to an output side of an existing transformer and can maintain a voltage through power conversion of a PWM (Pulse Width Modulation) method. .

In addition, the present invention relates to an intelligent power conversion device and method capable of using only a core, a coil, etc., which are the core of power conversion among existing transformers, and removing internal/external additional elements.

Currently, the distribution transformer adjusts the turn ratio by switching the internal tap, but it is a method of switching by opening the enclosure and putting a hand inside the insulating oil. Therefore, there is a disadvantage in that soundness and workability are very poor, and it is difficult to apply an on-load tap changer (OLTC) due to problems such as size and price.

There is a problem that protection facilities such as a fuse and a cut out switch (COS) that are opened when a secondary side failure occurs, must be equipped and installed, and other functions such as protection devices or power quality compensation cannot be implemented.

In addition, the power conversion device of the semiconductor switching method has not been used due to high cost in the past, but in recent years, price and stability have been remarkably improved, thereby securing competitiveness. Accordingly, there is a need to maintain voltage through power conversion and use only cores, coils, etc., which are the core of power conversion among existing transformers, and remove additional internal/external elements.

1. Korea Utility Model Registration No. 20-0347104 (Registration date: 2004.03.29) 2. Korean Patent Registration No. 10-1273354 (Registration Date: 2013.06.04)

The present invention has been proposed in order to solve the problem according to the above background technology, and can be linked to the output side of an existing transformer, and provides an intelligent power conversion device and method capable of maintaining voltage by power conversion of a PWM (Pulse Width Modulation) method. It has its purpose to provide.

In addition, an object of the present invention is to provide an intelligent power conversion apparatus and method capable of removing internal/external additional elements while using only cores and coils, which are the core of power conversion among existing transformers.

The present invention provides an intelligent power conversion device that can be linked to an output side of an existing transformer, and can maintain a voltage by power conversion of a PWM (Pulse Width Modulation) method in order to achieve the above-described problem.

The intelligent power conversion device,

A plurality of unit modules are individually selected and configured, the unit power conversion unit for converting power;

And a main control unit that controls the unit power conversion unit and is connected or disconnected from the unit power conversion unit by a detachable method.

At this time, the unit module, a switching circuit for converting power; And a filter circuit for removing noise from the converted power.

In addition, the switching circuit is characterized in that it converts the power into at least one of alternating current (AC) power and direct current (DC) power.

In addition, the switching circuit is characterized in that it includes a DAB (Dual Active Bridge) type converter for bidirectional transmission.

In addition, the switching circuit is characterized in that it is controlled through a zero voltage or zero current switching technique for bidirectional transmission.

In addition, the switching circuit is characterized in that it is controlled using a PWM (Pulse Width Modulation) signal.

In addition, the plurality of unit modules are connected in parallel.

In addition, the main control unit, the central processing unit for controlling the unit module; An input unit for inputting a user's command for the control; And a communication unit that communicates with an external controller for remote control during the control.

In addition, the main control unit is characterized in that it is disposed in the cabinet body in which a plurality of insertion grooves are formed.

In addition, the unit module is characterized in that it comprises a module body and a handle formed at the front end of the module body so as to be attached to and detached from the insertion groove.

In addition, the module body is characterized in that it is inserted and fixed in the insertion groove through a slot method or a bushing method.

In addition, the number of turn-ons of the unit module is characterized in that it is calculated using the amount of power.

In addition, the amount of power is calculated at the same time as supplying a load after the entire unit module is turned on at the initial driving stage.

In addition, the amount of power is calculated at the same time as supplying a load after the entire unit module is turned on at the initial driving stage.

In addition, in order to maintain the first reference ratio set in advance among the rated power of the entire unit module, the number of turn-ons of the unit module is the power margin obtained by calculating the instantaneous power from the rated power of all unit modules currently turned on. If it is less than 1 reference ratio, it is characterized in that it is increased by 1.

In addition, the number of turn-ons of the unit module is reduced by one when the power margin is equal to or greater than the second reference ratio by adding the instantaneous power to the power margin obtained from the rated power of all unit modules currently turned on. do.

On the other hand, another embodiment of the present invention includes the steps of: (a) connecting or disconnecting, by a main control unit, a unit power conversion unit in which a plurality of unit modules are individually selectively configured and a detachable method; (b) controlling the unit power conversion unit by the main control unit; And (c) converting power by the unit power conversion unit according to the control.

According to the present invention, it is possible to improve usability and reliability by excluding additional functions of the distribution transformer, and it is possible to secure customer voltage stability, transmission distance improvement, reduction of fault sections, and system voltage quality.

In addition, as another effect of the present invention, it is possible to secure effects such as cost reduction, power failure suppression, and efficiency and reliability improvement by implementing a parallel modular method.

In addition, another effect of the present invention is that when the load demand exceeds the device rated power or receives a central command, the voltage can be lowered to a certain level to reduce the inactive load amount.

In addition, as another effect of the present invention, a DER-AVM (Distributed Energy Resource Active Voltage Manager) function is implemented to monitor the voltage at the installation point of the distributed power, The point is that it is possible to control the output power factor of distributed power by giving a control command to the power factor control inverter.

1 is a conceptual diagram of a modular type single-phase power conversion device according to an embodiment of the present invention.
2 is a conceptual diagram of a modular power conversion device for three-phase transformation according to an embodiment of the present invention.
3 is a conceptual diagram in which the power conversion device shown in FIG. 1 is applied to an existing transformer.
4 is a block diagram of the configuration of the power conversion device shown in FIG. 3.
5 is an example in which the power conversion device shown in FIG. 3 is applied to an end of a line.
6 is an example in which the power conversion device shown in FIG. 3 is applied to a line interruption.
7 is an example of a power conversion circuit diagram of the power conversion device shown in FIG. 3.
8 is an implementation example of a voltage/current control algorithm for controlling the power conversion circuit shown in FIG. 7 according to an embodiment of the present invention.
9 is a flowchart illustrating a process of calculating the number of turn-on unit modules according to an embodiment of the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, and it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing each drawing, similar reference numerals are used for similar elements. Terms such as first and second may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another component.

For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term “and/or” includes a combination of a plurality of related stated items or any of a plurality of related stated items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Shouldn't.

Hereinafter, an intelligent power conversion apparatus and method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram of a modular type single-phase power conversion device 100 according to an embodiment of the present invention. Referring to FIG. 1, the power conversion device 100 includes a cabinet body 110 in the form of a cabinet, and first to third unit modules 120-1 to 120-3 detachable from the cabinet body 110. It can be configured.

An insertion groove 111 is formed in the cabinet body 110 so that the first to third unit modules 120-1 to 120-3 are inserted. The first to third unit modules 120-1 to 120-3 are configured in a modular manner, and the first to third unit modules 120-1 to 120-3 are It consists of a handle (120-3-2). Of course, a male terminal (not shown) protruding from the ends of the first to third unit modules 120-1 to 120-3 is inserted inside the insertion groove 111 formed in the space of the cabinet body 110 A female terminal (not shown) may be formed.

Of course, the male terminal and the female terminal are each composed of a pair of a cathode and an anode, and the pair of male and female terminals may be arranged at regular intervals. Of course, the male terminal and the female terminal can be configured in reverse. That is, the female terminal may be formed to protrude from the ends of the first to third unit modules 120-1 to 120-3, and the male terminal may be formed inside the insertion groove 111. The female terminal may be a slot type. In addition, a bushing type in which wiring work is minimized may be used for fastening the first to third unit modules 120-1 to 120-3 and the cabinet body 110.

The first to third unit modules 120-1 to 120-3 shown in FIG. 1 represent a single phase. In addition, for fastening of the first to third unit modules 120-1 to 120-3 and the cabinet body 110, a bushing type that minimizes wiring work is easy to attach and detach.

2 is a conceptual diagram of a modular type power conversion device 200 for three-phase transformation according to an embodiment of the present invention. Referring to FIG. 2, the cabinet body 110 includes first to third unit modules 220-1 to 220-3 in one phase 220 to represent three phases.

The cabinet body 110 and the module body 120-3-1 may be coated on their surfaces for waterproof and dustproof so as not to be affected by fine dust in the rain. Nano spray coating method can be used. The material may be urethane, silicone, or the like. In addition, the cabinet bodies 110 and 210 may be installed on the electric pole using a fastening bracket.

As shown in Figs. 1 and 2, if the same unit module is manufactured and responds to various capacities according to the number of units, the price of the device can be significantly lowered. It is very advantageous for quick maintenance. That is, this is because the unit module performs only the power conversion function, and the cabinet bodies 110 and 210 are separated to mount the operation and control system.

3 is a conceptual diagram in which the power conversion device 100 shown in FIG. 1 is applied to an existing transformer 310. Referring to FIG. 3, in a state in which the existing transformer 310 is already installed, a power conversion device 100 according to an embodiment of the present invention may be additionally installed. Existing transformer 310 receives transmission power of 22.9kV and steps down, converts it to alternating current (AC) 154 to 286V, and supplies it to the power conversion device 100, the power conversion device 100 is AC 220V or DC (Direct Current). ) Convert to 450V. In particular, the output voltage of the power conversion device 100 is controlled by remote control.

4 is a block diagram of the configuration of the power conversion apparatus 100 shown in FIG. 3. The power conversion device 100 is largely divided into a unit module to perform only a power conversion function, and the cabinet bodies 110 and 210 to mount an operation and control system. Referring to FIG. 4, the power conversion device 100 may include a main control unit 410 and a unit power conversion unit 420 connected to the main control unit 410 to convert power according to control. I can.

The unit power conversion unit 420 includes unit modules 120-1, 120-2, ..., and each unit module converts power. The unit modules 120-1, 120-2,... include a switching circuit 421 that performs a conversion function to increase or decrease the power, and a filter circuit 422 that removes noise from the converted power after the conversion function is performed. It can be composed of.

The main control unit 410 includes a central processing unit 411 that controls the unit modules 120-1, 120-2,..., an input unit 412 for inputting a user's command, and an external controller 413 for remote control. It may be configured to include a communication unit 414 that communicates with, a storage unit 415 for storing setting information, a program, and data, a display unit 416 for displaying a setting screen, and the like.

The central processing unit 411 may be configured with a microprocessor, a microcomputer, or the like, and an algorithm for calculating the number of turn-on modules may be programmed as the unit modules are attached and detached. Accordingly, the central processing unit 411 may be implemented in software and/or hardware. In hardware implementation, application specific integrated circuit (ASIC), digital signal processing (DSP), programmable logic device (PLD), field programmable gate array (FPGA), processors, microprocessors, and other devices designed to perform the above-described functions It may be implemented as an electronic unit or a combination thereof. In software implementation, software component (element), object-oriented software component, class component and work component, process, function, property, procedure, subroutine, segment of program code, driver, firmware, microcode, data , Databases, data structures, tables, arrays, and variables. Software, data, etc. may be stored in memory and executed by a processor. The memory or processor may employ various means well known to those skilled in the art.

The input unit 412 is composed of a button, a touch screen, a speaker, etc., and may receive a user's voice or operation.

The storage unit 415 performs a function of storing setting information, programs, software, processed data, and the like. To this end, the storage unit 415 may be a memory provided in the central processing unit 411 or may be a separate memory. Therefore, flash memory disk (SSD: Solid State Disk), hard disk drive, flash memory, EEPROM (Electrically erasable programmable read-only memory), SRAM (Static RAM), FRAM (Ferro-electric RAM), PRAM (Phase-change RAM) ), non-volatile memory such as MRAM (Magnetic RAM), and/or volatile memory such as Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), and Double Data Rate-SDRAM (DDR-SDRAM) Can be.

The display unit 416 may be a liquid crystal display (LCD), a light emitting diode (LED) display, a plasma display panel (PDP), an organic LED (OLED) display, a touch screen, a flexible display, and the like.

The communication unit 414 may be communicatively connected with the external controller 413 using wired or wireless communication. To this end, a communication circuit element, a processor, or the like may be configured. Communication connection is low-speed/high-speed PLC (Power Line Communication), ZigBee, RS-485, USB (Universal Serial Bus) communication, Wifi (Wireless Fidelity), WiSUN (Wireless Smart Utility Network), LoRa, NB-lOT (NarrowBand-Internet). of Things), etc. may be used.

Therefore, even if the input-side voltage fluctuates in a large width (about ±30%), the output maintains the set value, and the operator can easily change it using a wired/wireless control system according to the system situation. In addition, it is possible to replay and/or analyze an event voltage/current waveform when an abnormality occurs by using the data collected through the display unit 416. In addition, time information may be provided by applying a GPS (Global Positioning System) or a real time clock (RTC) module including a secondary battery.

5 is an example in which the power conversion devices 100 and 200 shown in FIG. 3 are applied to an end of a line. Referring to FIG. 5, a power conversion device 100 is installed on the pole 50 to simultaneously supply AC power and DC power. DC power is supplied to the charger 510, and AC power is supplied directly to the customer 520. The charger 510 may be a charger for an electric vehicle or an energy storage system (ESS). Of course, the charger 510 may be connected to the photovoltaic power generation 530 to supply power to the customer 520. Of course, the power conversion device 100 may be connected to the existing transformer 310.

6 is an example in which the power conversion apparatuses 100 and 200 shown in FIG. 3 are applied to a line interruption. Referring to FIG. 6, a power conversion device 100 is installed on an intermediate line. Of course, in this case, it is not connected to the existing transformer 310, and only the power conversion device 100 may be installed alone. 5 and 6, the effect of increasing the voltage stability of the customer and/or the transmission distance of the low-voltage line can be secured.

7 is an example of a power conversion circuit diagram of the power conversion apparatus 100 and 200 shown in FIG. 3. Referring to FIG. 7, the power conversion circuit may include a switching circuit 421 and a filter circuit 422. The switching circuit 421 converts power through a converter in which the switching element 710 is configured. In addition, by including the transformer 740 high AC power -> low AC power, AC power -> DC power conversion is made. The converter may be a DAB (Dual Active Bridge) type converter for bidirectional transmission. In addition, the switching element 710 may be a SiC power semiconductor, a field effect transistor (FET), a metal oxide semiconductor FET (MOSFET), an insulated gate bipolar mode transistor (IGBT), a power rectifying diode, or the like.

The transformer 740 may be a nano-crystalline core high frequency transformer. In addition, it is possible to maintain a high efficiency of 97% or more bidirectional power conversion at the rating by using a zero voltage/zero current switching technique. The filter circuit 422 may include an inductor 730 and a capacitor 720.

8 is an implementation example of a voltage/current control algorithm for controlling the power conversion circuit shown in FIG. 7 according to an embodiment of the present invention. Referring to FIG. 8, a voltage control 810 and a current control 820 are combined by a summer to generate PWM signals S1, S2, S3, and S4 by a pulse width modulation (PWM) generator 830. Of course, FIG. 8 is an example and various algorithms are possible.

9 is a flowchart illustrating a process of calculating the number of turn-on unit modules according to an embodiment of the present invention. Referring to FIG. 9, turn-on all unit modules (120-1 to 120-3, 220-1 to 220-3) at the initial stage of operation, supply a load, and calculate the amount of power at the same time to calculate the appropriate number of turn-on unit modules. To (steps S910 and S920). When the appropriate number of turn-on unit modules is calculated, the excess unit modules are turned off (step S930).

The power margin should be maintained at 10% of the unit module rated power. 10% is an example, and the value may vary depending on the specifications of the power conversion device. This can be expressed as an equation as follows.

If the unit module capacity is 20kVA, the power margin of 2kVA or more must be maintained. Therefore, when the power margin becomes less than the set value (10% of the unit module capacity), one unit module is additionally turned on (steps S940 and S941).

Conversely, when the power margin of the currently turned-on unit module becomes 110% or more by adding the margin set value (10%) to the unit module capacity, one module is turned off (steps S950, S960, S961).

In addition, the steps of the method or algorithm described in connection with the embodiments disclosed herein are implemented in the form of program instructions that can be executed through various computer means such as a microprocessor, a processor, and a CPU (Central Processing Unit), and are computer-readable. It can be recorded on any media. The computer-readable medium may include a program (command) code, a data file, a data structure, or the like alone or in combination.

The program (command) code recorded on the medium may be specially designed and configured for the present invention, or may be known to and usable by a person skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROM, DVD, Blu-ray, and the like, and ROM, RAM ( A semiconductor memory device specially configured to store and execute program (instruction) codes such as RAM), flash memory, and the like may be included.

Here, examples of the program (instruction) code include not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operation of the present invention, and vice versa.

100: intelligent power conversion device
110: cabinet body
111: insertion groove
120-1,120-2,120-3: 1st to 3rd unit modules
120-3-1: module body
120-3-2: handle

Claims (17)

A plurality of unit modules 120-1 to 120-3 and 220-1 to 220-3 are individually selectively configured, and a unit power conversion unit 420 for converting power;
A main control unit 410 that controls the unit power conversion unit 420 and is connected or disconnected from the unit power conversion unit 420 by a detachable method;
Intelligent power conversion device comprising a. The method of claim 1,
The unit modules 120-1 to 120-3, 220-1 to 220-3,
A switching circuit 421 that converts power; And
Intelligent power conversion device comprising a; filter circuit (422) for removing noise from the converted power.
The method of claim 2,
The switching circuit 421 converts the power into at least one of alternating current (AC) power and direct current (DC) power.
The method of claim 3,
The switching circuit 421 is an intelligent power conversion device, characterized in that it comprises a DAB (Dual Active Bridge) type converter for bi-directional transmission.
The method of claim 4,
The switching circuit 421 is an intelligent power conversion device, characterized in that controlled through a zero voltage or zero current switching technique for bidirectional transmission.
The method of claim 5,
The switching circuit 421 is an intelligent power conversion device, characterized in that the control using a PWM (Pulse Width Modulation) signal (S1 to S4).
The method of claim 1,
Intelligent power conversion device, characterized in that the plurality of unit modules (120-1 to 120-3, 220-1 to 220-3) are connected in parallel. The method of claim 1,
The main control unit 410 is
A central processing unit 411 for controlling the unit modules 120-1 to 120-3 and 220-1 to 220-3;
An input unit 412 for inputting a user's command for the control; And
And a communication unit 414 communicating with an external controller 413 for remote control during the control.
The method of claim 1,
The main control unit 410 is an intelligent power conversion device, characterized in that disposed in the cabinet body (110) in which a plurality of insertion grooves (111) are formed.
The method of claim 9,
The unit modules 120-1 to 120-3 so as to be attached and detached to the insertion groove 111,
Intelligent power conversion device comprising a module body (120-3-1) and a handle (120-3-2) formed at the front end of the module body (120-3-1).
The method of claim 10,
Intelligent power conversion device, characterized in that the module body (120-3-1) is inserted and fixed in the insertion groove (111) through a slot method or a bushing method.
The method of claim 1,
Intelligent power conversion device, characterized in that the number of turn-on of the unit modules (120-1 to 120-3) is calculated using the amount of power.
The method of claim 12,
The power amount is calculated at the same time as supplying a load after the entire unit modules (120-1 to 120-3) are turned on at the initial driving stage.
The method of claim 12,
The power amount is calculated at the same time as supplying a load after the entire unit modules (120-1 to 120-3) are turned on at the initial driving stage. The method of claim 12,
The number of turn-on of the unit modules 120-1 to 120-3 is that the power margin is currently turned on in order to maintain a preset first reference ratio among the rated power of the entire unit modules 120-1 to 120-3. Intelligent power conversion device, characterized in that the power margin of the instantaneous power from the rated power of all unit modules is increased by one if less than the first reference ratio.
The method of claim 15,
The number of turn-ons of the unit modules 120-1 to 120-3 is greater than the second reference ratio by adding the first reference ratio to the power margin obtained by calculating the instantaneous power from the rated power of all unit modules currently turned on. Intelligent power conversion device, characterized in that the reduction by one.
(a) the main control unit 410 is connected to the unit power conversion unit 420 in which a plurality of unit modules 120-1 to 120-3 and 220-1 to 220-3 are individually selectively configured by a detachable method or Released;
(b) controlling the unit power conversion unit 420 by the main control unit 410; And
(c) converting, by the unit power conversion unit 420, power according to the control;
Intelligent power conversion method comprising a.

Images