KR20120133922A - Smart plug and power quality monitoring system thereof - Google Patents

Abstract

PURPOSE: Smart plug capable of obtaining voltage and current data with a high sampling frequency from an electric device and a power quality monitoring system using the same. CONSTITUTION: A smart plug(100) includes a plug(110), a converter(120), a transformer(130), and a communication module(140). The plug is connected with an electric device. The converter obtains voltage and current data from the electric device to convert the same into digital data. The transformer transforms the voltage and current data inputted to the converter. The communication module transmits the digital data to the outside. [Reference numerals] (10) Plug; (120) Converter; (140) Communication module; (5) Electric device

Description

Smart plug and power quality monitoring system

The present invention relates to a smart plug and a power quality monitoring system using the same. More particularly, the present invention relates to a smart plug and a smart plug which acquire and transmit power related data of an individual load in real time. The present invention relates to a power quality monitoring system using a smart plug for wirelessly transmitting and storing wirelessly.

In response to rapid price increases in oil and natural gas, the power industry is expected to see significant and rapid changes in the structure, operation, planning and regulation of the power industry.

Recently, a smart grid has been introduced to optimize energy efficiency by exchanging power usage information in real time in a bidirectional real time through a combination of a power network and a communication network.

In the smart grid, independent operation is carried out by the introduction of distributed power sources centered on renewable energy, and the existing power system is provided by providing services based on intelligence and many other technologies to respond in real time to the needs of consumers. It overcomes this inefficiency.

AMI (Advanced Metering Infrastructure) is required as a core system for the operation of this smart grid, and it is a system that collects and interprets various information related to power usage, and based on real-time electricity tariff, mutual recognition based demand response between suppliers and consumers ( It is an essential means for realizing DR, Demand Response.

An AMI typically consists of four basic technologies: intelligent meters, smart meters, hardware and software, including consumer demand response devices, power information management systems, communications technologies, and networks. It is the most important device, and it is an electronic instrument that measures the amount of electricity at various time intervals and transfers the measured information to other devices through communication.

Due to the evolution of the power system to the smart grid and changes in the electricity trading environment, various smart meters are currently being developed and used at home and abroad, and based on this, they are also linked to the development of energy management and solutions to effectively improve power usage and efficiency. have.

However, smart meters developed at home and abroad do not include a function of providing such information about items that need to be provided to consumers, such as power quality, or provide a very insufficient amount of information even if the information is provided. . In addition, the sampling frequency of the voltage and current data acquired through the smart meter is low, thereby reducing the amount and accuracy of the data. Therefore, when using an analysis program that analyzes the information and provides the information, the information provided to the consumer may also have a problem in accuracy, and there is a possibility of distortion.

Therefore, in order to solve these problems by acquiring more accurate voltage and current data, and to analyze the acquired data to provide more accurate information to consumers through an analysis program, and to provide more various information in the future, What is needed is a device that can obtain more accurate voltage and current data. In addition, there is a need for a system that can transmit and store acquired information quickly and efficiently through wireless communication without installing additional communication lines and changing the structure in the home.

The present invention is to solve the above problems, to provide a smart plug that can obtain accurate voltage and current data in order to obtain voltage and current data from the electrical device to provide accurate power quality information to the consumer.

In addition, the present invention provides a power quality monitoring system using a smart plug that can transmit and store power-related data obtained from a smart plug quickly and efficiently through wireless communication.

Problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

Smart plug according to an embodiment of the present invention for achieving the above object, the plug (plug) for connecting with the electrical device; A converter which obtains voltage and current data from the electric machine and converts the data into digital data; A transformer for modifying voltage and current data input to the converter; And a communication module for transmitting the digital data to the outside.

Power quality monitoring system using a smart plug according to another embodiment of the present invention for achieving the above object is connected to an electrical device to obtain the voltage and current data to convert to digital data, and transmits the digital data to the outside A plurality of smart plugs; A repeater for generating a data packet by integrating digital data transmitted from the plurality of smart plugs and retransmitting the data packet; And a server storing a data packet transmitted from the repeater.

Other specific details of the invention are included in the detailed description and drawings.

According to the present invention, it is possible to obtain voltage and current data at a high sampling frequency from an electric device to provide accurate power quality information to the consumer.

In addition, the power quality information obtained from the smart plug can be transmitted and stored quickly and efficiently through wireless communication.

1 is a block diagram of a smart plug according to an embodiment of the present invention.
2 is a circuit diagram of a smart plug according to an embodiment of the present invention.
3 is a diagram illustrating a range of differential input modes input to a converter of a smart plug.
4 is a diagram illustrating conversion of voltage data of a smart plug using Atmega8 and Atmega128.
5 is a diagram illustrating current data measured through an oscilloscope and a smart plug, respectively.
6 is a block diagram of a power quality monitoring system according to an embodiment of the present invention.
7 is a block diagram of a power quality monitoring system according to another embodiment of the present invention.
FIG. 8 is a diagram illustrating a specific embodiment of the power quality monitoring system of FIG. 6.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used in a sense that can be commonly understood by those skilled in the art. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a block diagram of a smart plug according to an embodiment of the present invention.

The smart plug 100 includes a plug 110, a converter 120, a transformer 130, and a communication module 140.

The plug 110 is connected to the electric device 5 and has a general plug form and is directly connected to the electric device 5. The plug 110 forms an outer housing (not shown) of the smart plug 100 so that the converter 120, the transformer 130, and the communication module 140 may be configured therein.

The converter 120 obtains voltage and current data from the electric device 5 and converts the data into digital data. The converter 120 converts the data to transmit data more quickly and accurately.

Here, the converter 120 uses a micro controller unit (MCU) equipped with a memory for embedding a program. That is, the microcontroller unit, aka MCU is employed in the smart plug 100 to act as the brain of the smart plug 100, and serves to control the smart plug 100. Microcontroller units can incorporate ROM and RAM circuits and are manufactured in chip form.

In particular, the memory provided in the microcontroller unit adopts a flash memory to store various programs required for the smart plug 100. For example, the memory provided in the converter 120 may store a power analysis program for generating information on power quality by analyzing voltage and current data obtained from the electric device 5. This enables basic energy usage patterns, power quality and harmonic analysis through the flow of voltage, current and power.

Generally used microcontroller units are classified into 8-bit cores, 16-bit cores, 32-bit cores, and the like according to the amount of bits to be operated at a time. The 8-bit cores are AVR series and 8051 series. The 16-bit cores are the S12 series and the x86 series, and the 32-bit cores are the ARM7 series and the ARM Cortex-M3 series.

The smart plug 100 of the present invention constitutes a converter 120 employing a microcontroller unit using an AVR series developed by Atmel. Atmel AVR includes AVR UC3, AVR XMEGA, mega AVR and tiny AVR series. As described above, since the AVR is one of the MCUs, the central processing unit and the small-capacity flash ROM are integrated in one IC.

It is possible to apply a number of MCU to the smart plug 100 of the present invention, but actually configured by adopting the MCU of the commonly used AVR series, the price and for the production and application of the actual smart plug 100 among the various AVR Compare based on performance to select the most efficient AVR. To this end, we selected the Atmega series, the most commonly used 8-bit MCU, and compared the performance of Atmega8 and Atmega128, the most widely used chips among these Atmega series, which will be described later. Of course, other MCU such as 8-bit core, 16-bit core, 32-bit core including other Atmega series besides the Atmega8 and Atmega128 may be used as the converter 120 of the smart plug 100.

The transformer 130 denatures the voltage and current data input to the converter 120. That is, the voltage and current input to the converter 120 are transformed and converted into the rated voltage and current range of the converter 120.

Transformer 130 has a current transformer 132 and a predetermined resistor 134, the current transformer 132 current flows from the electrical device 5, the current flowd by the current transformer 132 is the predetermined current The resistor 134 converts the input voltage and / or current into the converter's rated voltage and / or current range.

The MCU is used to implement the converter 120, and the MCU is driven only when a current is input within the rated range of the MCU. In particular, the AVR, which is a representative MCU configured in the smart plug 100 of the present invention, may receive only a voltage value as input data. In order to implement an AVR capable of receiving only a voltage value as an input, the size of the voltage data needs to be reduced within the input range of the AVR. In the case of the current data, the AVR needs to be converted into voltage data within the input range. To this end, a current transformer (132, CT) is applied to reduce the magnitude of the current.

The communication module 140 transmits the digital data converted by the converter 120 to the outside. In particular, the communication module 140 may be a Bluetooth communication module for transmitting the digital data through Bluetooth communication.

Further, the smart plug 100 may further include a storage module (not shown) inside the smart plug 100 so as to store the digital data converted by the converter 120 by itself.

2 is a circuit diagram of a smart plug according to an embodiment of the present invention.

In Fig. 2, the current Io of the primary side, i.e., the electrical device 5, to be measured, is converted to I2 by the current transformer 132, and finally by the resistor 134, to the voltage signal E2. That is, the input current flowing from the electric device 5 is current-flowed by the current transformer 132 constituting the transformer 130, and is converted into the rated voltage of the converter 120 by the resistor 134 to the converter 120. Is entered. In addition, the converter 120 may obtain the current Io by measuring the voltage E2.

When the AVR, which is an MCU, is implemented in the smart plug 100 as the converter 120, the AVR can receive only voltage values as input data, and the single conversion mode and differential are largely dependent on the range and type of the voltage input. There are two input modes: differential input mode.

First, in the single conversion mode, only a voltage value between 0 and Vref can be received as an input, and converted into a digital value according to Equation 1 below. In this case, Vref means the voltage supplied to the power of the AVR and becomes the range of the converted voltage. It is also possible to power the AVR accordingly to select Vref as an arbitrary value to set the desired criteria.

In general, Vref is able to input a voltage value between 0V and 5V at 5V, but when using the single conversion mode, it cannot receive the negative current value of the actual data. Due to this, only half-wave data is obtained, which is different from the actual voltage and current data of the electric device 5 to which the smart plug 100 is applied, and since the distorted information may be provided therefrom, the normal mode may not be utilized. There will be no.

In another mode, the differential input mode, as shown in FIG. 3, the voltage input range has -Vref to Vref. 3 is a diagram showing the range of the differential input mode. The horizontal axis is differential input, and the input unit is V (Voltage). In addition, the vertical axis represents a value obtained by digitally converting a voltage input as an output code. When the differential input mode is used, a negative voltage value can be received as an input, thereby converting an actual analog voltage waveform into digital data as shown in Equation 2 below.

In order to utilize the MCU, in particular, the AVR, which can receive only the voltage value, as such, the size of the voltage data is reduced within the input range of the AVR, and the current data is converted into the voltage data within the input range. To ensure stability.

Thus, the current Io actually flowing due to the operation of the electrical device 5 using the transformer 130 shown in FIG. 2 decreases and flows at a constant rate through the current transformer 132 (I2). Is converted into an AVR, i.e., a voltage E2 within the input range of the converter 120 by a resistor 134 connected across the current transformer 132. The converter 120 converts the voltage signal generated by the resistor 134 into digital data as an input.

Then, the voltage and current data converted into digital data is transmitted to and stored in an external data storage device through the communication module 140, in particular, the Bluetooth communication module. In addition, the data stored as a voltage value may be converted into an actual value through the size and current ratio of the applied resistor 134 and stored. In addition, a separate storage module (not shown) in the smart plug 100 may be provided to store the converted digital data in the smart plug 100.

In addition, a separate display module (not shown) may be provided to guide the user with power-related data or digitally converted data. For example, information on power quality may be provided to the user through voltage and current data, respective voltage outage information, power factor and frequency, and power direction.

The converter 120 of the smart plug 100 is an MCU, and the Atmega series is selected among the most commonly used 8-bit AVRs. The performance comparison of the Atmega8 and Atmega128, the most widely used chips among the Atmega series, is performed. .

4 is a diagram illustrating conversion of voltage data of a smart plug using Atmega8 and Atmega128.

In FIG. 4, when the performance is compared with respect to the change of the same voltage signal, it can be seen that the Atmega8 generates noise between digital conversions and causes distortion of data. In contrast, the Atmega128 shows that changes in the voltage signal are normally converted to digital signals.

Although Atmega128 is about 5 times more expensive than Atmega8, when using Atmega8 during data acquisition, it is difficult to provide accurate power-related information to consumers when digital signals are distorted, so the performance is verified by Smart Plug (100) with Atmega128. It was.

The converter 120 applied Atmega128, the current ratio of the current transformer 132 was applied to 1000: 1, the resistor 134 connected to the current transformer 132 has a size of 644Ω. It is confirmed that the current flow ratio is affected by the connection of the resistor 134 having the size, and the correct current flow ratio after the connection of the resistor 134 is 964.28: 1. In addition, 5.06V was given as an input power supply to the AVR, which is the converter 120. A 0.2 kW class motor was used as the electric machine 5 for the test, and the motor was operated under a no load state with a current of 2.9 A flowing at 220V.

For accurate performance verification, the secondary side of the current transformer 132, i.e., the voltage and current of the resistor is measured through an oscilloscope, and stored as a voltage value through the smart plug 100 having a current ratio of Atmega128 and 1000: 1. Compared with the current data value.

5 is a diagram illustrating current data measured through an oscilloscope and a smart plug, respectively.

In FIG. 5, it can be seen that the current change of the resistance side measured through the oscilloscope at the top and the current change of the resistance side measured through the smart plug 100 at the bottom are very similar. In practice, the average value of the voltage on the resistance side measured by the oscilloscope was about 3.86V, which is almost similar to the average value of the voltage data of the resistance side measured by the smart plug 100 is about 3.9V.

In addition, as a result of displaying the data obtained from the current data graph measured through the smart plug at the bottom of FIG. 5 as a small circle, it was found that about 33 to 34 pieces of data were obtained per cycle. Since the 220V AC voltage has one cycle of 60Hz, the performance of the converter 120 employing the Atmega128 has a sampling frequency of about 2000Hz.

6 is a block diagram of a power quality monitoring system according to an embodiment of the present invention.

The power quality monitoring system 10 includes a plurality of smart plugs 100, a repeater 200, and a server 300.

The smart plug 100 is connected to the electric device 5 to obtain voltage and current data, convert it into digital data, and transmit the digital data to the outside. The smart plug 100 may be connected to one electric device 5 or the plurality of electric devices 5 may be connected to one smart plug 100.

In FIG. 6, the smart plug 100 is directly connected to each electric device 5 through the plug 110, and the analog data acquired by the plurality of smart plugs 100 is converted into digital data to the repeater 200. The digital data is synthesized through the repeater 200 and transmitted to the server 300 for storage. At this time, in order to distinguish each electric device 5, the electric device 5, which is a slave, is assigned a number.

As described above, the smart plug 100 includes a plug 110 for connecting to the electric device 5, a converter 120 for obtaining voltage and current data from the electric device 5 and converting the data into digital data. The transformer 130 includes a transformer 130 for modifying voltage and current data input to the converter 120, and a communication module 140 for transmitting the digital data to the outside.

Here, the converter 120 is a microcontroller unit having a flash memory for embedding an analysis program for analyzing voltage and current data obtained through the plug 110. In addition, the transformer 130 converts the current data input to the converter 120 into voltage data within the rated voltage range of the converter 120, or converts the voltage data input to the converter 120 into the rating of the converter. Drop to voltage data within the voltage range. In addition, the communication module 140 communicates wirelessly using Bluetooth communication.

The repeater 200 generates a data packet by integrating the digital data transmitted from the plurality of smart plugs 100 and retransmits the data packet to the server 300. In this case, the repeater 200 may be implemented using a microcontroller unit having a plurality of communication ports and at least one flash memory. Atmel's various AVRs described above may be used as the repeater 200.

The microcontroller unit may control the data passing through the repeater by storing a packet generation program that integrates digital data transmitted from the plurality of smart plugs 100 to generate a data packet in a flash memory.

In addition, at least one communication port of the plurality of communication ports provided in the microcontroller unit implementing the repeater 200 may be implemented to serve as a transmission port for transmitting the data packet to the server 300, a plurality of communication The remaining communication ports except at least one communication port of the ports may be implemented to serve as a receiving port for receiving data transmitted from the smart plug 100. That is, at least one of the plurality of communication ports provided in the repeater 200 serves as a transmission port for transmitting data to the server 300, and the rest serves as a receiving port for receiving data from the smart plug 100. To perform.

In addition, the repeater 200 may include a Bluetooth communication module so as to enable wireless communication between the smart plug 100 and the server 300. Of course, it will be apparent to those skilled in the art that various wireless communication networks such as Zigbee can be applied in addition to Bluetooth communication.

The server 300 stores the data packet transmitted from the repeater 200. The data packet stored in the server 300 is analyzed through a PC or the like acting as a master and the power quality related information is provided to the consumer. The server 300 serves as a storage of data packets to be transmitted, and of course, the server 300 may be provided in a master such as a PC.

The server 300 further includes a communication module for receiving a data packet transmitted from the repeater 200, and the communication module may use various wireless communication modules such as a Bluetooth communication module and a Zigbee communication module.

The information stored in the server 300 may be analyzed through a PC and the like, and information about basic energy usage patterns and power quality may be provided to a power provider or a user through a display device (not shown).

7 is a block diagram of a power quality monitoring system according to another embodiment of the present invention.

In the case of FIG. 7, unlike FIG. 6, the repeater 200 is omitted, and the data obtained by the smart plug 100 directly connected through the plug 110 and the plurality of slaves 5, which are the electric devices 5, is smart. The plug 100 converts the data into digital data and transmits the digital data to the server 300.

When using a wireless communication such as ZigBee, since only one receiving port of the server 300 for data storage is required for the ZigBee transmission module existing in each smart plug 100, 1: N communication is possible, The advantage is that the number required is small.

However, when the number of uses of the Zigbee receiving module is one, it is impossible to simultaneously store multiple data transmitted. That is, the data is sequentially received for a predetermined time in order in the transmitting module. Thus, when data is received for one transmission module, disconnection of data may occur because the reception is impossible even if data of the other electric device 5 is transmitted.

It is possible to use Bluetooth communication instead of Zigbee communication, and unlike Zigbee communication, one receiving module corresponds to one transmitting module. Therefore, although there is an advantage in that all the data to be transmitted at the same time, the number of the receiving module is required as many as the number of the Bluetooth transmitting module of the smart plug 100. Therefore, in FIG. 6, the necessary number of communication modules is reduced by utilizing the repeater 200.

In the case of FIG. 6, since the plurality of electric devices 5 transmit data to one of the repeaters 200, an appropriate number of electric devices 5 per repeater 200 need to be connected. This will be described with reference to FIG. 8.

FIG. 8 is a diagram illustrating a specific embodiment of the power quality monitoring system of FIG. 6.

Since the repeater 200 may be implemented using a microcontroller unit having a plurality of communication ports and at least one flash memory, the AVR may be the repeater 200. That is, the AVR is used as the repeater 200 to solve the limitation of the wireless communication due to the proper number of transmission and reception communication module and the communication distance or obstacle that may occur in the home.

For example, you can take advantage of the Atmega2560, one of the AVRs. Atmega2560 used as a repeater 200 has a total of four communication ports, three of which are used as receiving ports for receiving data transmitted from the three smart plugs 100, and the other one communication port. May be utilized as a transmission port for transmitting the data packet integrated in the repeater 200 to the server 300. That is, when the Atmega2560 is used as the repeater 200, three slaves 5, that is, three electric devices 5, may simultaneously transmit data to one repeater 200.

In addition, by implementing a plurality of repeaters 200, it is possible to manage three slaves (5), that is, the electric device (5), which is bundled into three. Through this, it is possible to manage by dividing the electric device 5 in a similar position by three.

Therefore, the number of Bluetooth receiving modules required by the server 300 is reduced, and the data of the electric devices 5 at similar positions are bundled by tying three pieces of data of the electric devices 5 transmitted to the repeater 200. Through 200 may be integrally manageable.

When the data is stored in the server 300 by using the repeater 200, if the data file is individually created and stored for each node of the repeater 200, each data is easily distinguished and the utilization of data is easy. That is, the slave device is assigned to the electric device 5, and the data transmitted according to each slave number is set to be stored, so that accurate data can be obtained and stored.

If the converter 120 of the smart plug 100 is implemented in Atmega128 and the repeater 200 is implemented in Atmega2560, it is possible to acquire data through a sampling frequency of 2000 Hz and to accurately acquire multiple data simultaneously through Bluetooth wireless communication. .

Smart plug 100 using a wireless communication and increasing the sampling frequency to obtain instantaneous data of the use voltage and current of the home PCC (Point of Common Coupling) and each electric device (5) and power quality monitoring using the same We have looked at the system 10. In particular, it was found that the AVR can be used as the converter 120 and the repeater 200, and data can be accurately obtained at a high sampling frequency of 2000 Hz using Bluetooth wireless communication.

Smart plug 100, which is a device that can acquire more accurate voltage and current data, and transmits the information obtained quickly and efficiently through wireless communication, and can simultaneously transmit and store the information through the repeater 200 Efficient power usage can be achieved between the power supplier and the power consumer from the system power quality monitoring system 10.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

10: power quality monitoring system 100: smart plug
110: plug 120: converter
130: transformer 140: communication module
200: repeater 300: server

Claims (15)

A plug for connecting with an electric device;
A converter for acquiring voltage and current data from the electric device and converting the data into digital data;
A transformer for modifying voltage and current data input to the converter; And
Smart plug including a communication module for transmitting the digital data to the outside. The method of claim 1,
The converter is a smart plug is a microcontroller unit having a memory for embedding the program. The method of claim 2,
The memory provided in the converter is a smart plug for storing a power analysis program for generating information on the power quality by analyzing the voltage and current data obtained from the electrical device. The method of claim 1,
The transformer has a current transformer and a predetermined resistance,
The current transformer current flows from the electric device, and the current flowd by the current transformer is converted into an input voltage within the rated voltage range of the converter by the predetermined resistance. The method of claim 1,
The communication module is a smart plug for transmitting the digital data via Bluetooth communication. A plurality of smart plugs connected to an electric device to obtain voltage and current data, convert the data into digital data, and transmit the digital data to the outside;
A repeater for generating a data packet by integrating digital data transmitted from the plurality of smart plugs and retransmitting the data packet; And
And a server for storing data packets transmitted from the repeater. The method according to claim 6,
The smart plug,
A plug that connects to an electrical device, a converter that acquires voltage and current data from the electrical device and converts the data into digital data, a transformer that modulates the voltage and current data input to the converter, and transmits the digital data to the outside. Power quality monitoring system including a communication module. 8. The method of claim 7,
And said converter is a microcontroller unit having a flash memory for embedding a program. 8. The method of claim 7,
And the transformer converts current data input to the converter into voltage data within a rated voltage range of the converter, and drops voltage data input to the converter into voltage data within a rated voltage range of the converter. 8. The method of claim 7,
The communication module, the power quality monitoring system for wireless communication using Bluetooth communication. The method according to claim 6,
The repeater includes a microcontroller unit having a plurality of communication ports and at least one flash memory. 12. The method of claim 11,
And the microcontroller unit stores in the flash memory a packet generation program for generating data packets by integrating digital data transmitted from the plurality of smart plugs. 12. The method of claim 11,
At least one communication port of the plurality of communication ports is a transmission port for transmitting the data packet to the server. 12. The method of claim 11,
And a remaining communication port except at least one communication port of the plurality of communication ports is a receiving port for receiving data transmitted from the smart plug. The method according to claim 6,
The server further comprises a communication module for receiving a data packet transmitted from the repeater.

Images