阅读说明：本技术 一种电能计量终端、方法、电力服务系统及介质 (Electric energy metering terminal, method, electric power service system and medium ) 是由 陈凯 黄亮 张方勇 吴宏军 郑亮亮 张平 于 2020-12-24 设计创作，主要内容包括：本发明提供一种电能计量终端、方法、电力服务系统及介质；所述电能计量终端包括：采样模块,用于对电网信号进行采样以获取采样信号,所述采样信号包括电压信号和电流信号；电能计量模块,与所述采样模块相连,用于根据所述采样信号获取用户的电能；隔离模块,与所述采样模块相连,用于对所述采样信号中的电压信号和电流信号进行隔离；模数转换模块,与所述隔离模块相连,用于对隔离后的采样信号进行模数转换；预处理模块,与所述模数转换模块相连,用于对模数转换后的采样信号进行预处理以获取用户的用电信息,并将所述用户的用电信息发送至电力服务平台。所述电能计量终端在获取用户的电能的同时,还能为电力服务平台提供用户的用电信息。(The invention provides an electric energy metering terminal, a method, an electric power service system and a medium; the electric energy metering terminal includes: the sampling module is used for sampling the power grid signal to obtain a sampling signal, and the sampling signal comprises a voltage signal and a current signal; the electric energy metering module is connected with the sampling module and used for acquiring the electric energy of the user according to the sampling signal; the isolation module is connected with the sampling module and used for isolating a voltage signal and a current signal in the sampling signal; the analog-to-digital conversion module is connected with the isolation module and is used for performing analog-to-digital conversion on the isolated sampling signals; and the preprocessing module is connected with the analog-to-digital conversion module and used for preprocessing the sampling signal after the analog-to-digital conversion to acquire the power utilization information of the user and sending the power utilization information of the user to the power service platform. The electric energy metering terminal can provide the electricity utilization information of the user for the electric power service platform while acquiring the electric energy of the user.)

1. An electric energy metering terminal, characterized in that, electric energy metering terminal includes:

the sampling module is used for sampling the power grid signal to obtain a sampling signal, and the sampling signal comprises a voltage signal and a current signal;

the electric energy metering module is connected with the sampling module and used for acquiring the electric energy of the user according to the sampling signal;

the isolation module is connected with the sampling module and used for isolating a voltage signal and a current signal in the sampling signal;

the analog-to-digital conversion module is connected with the isolation module and is used for performing analog-to-digital conversion on the isolated sampling signals;

and the preprocessing module is connected with the analog-to-digital conversion module and used for preprocessing the sampling signal after the analog-to-digital conversion to acquire the power utilization information of the user and sending the power utilization information of the user to the power service platform.

2. The electric energy metering terminal of claim 1, wherein: the preprocessing module carries out load identification according to the waveform of the sampling signal after the analog-to-digital conversion; the electricity consumption information of the user includes a result of the load identification.

3. The electric energy metering terminal of claim 1, wherein: the preprocessing module acquires the power quality of a user according to the sampling signal after the analog-to-digital conversion; the electricity utilization information of the user comprises the power quality of the user.

4. The electric energy metering terminal of claim 1, wherein: the preprocessing module acquires the time characteristics of the electricity utilization condition of the user according to the sampling signal after the analog-to-digital conversion; the electricity consumption information of the user includes the time characteristic.

5. The electric energy metering terminal of claim 1, wherein the sampling module comprises:

the current sampling unit is used for sampling the power grid signal to acquire a current signal in the sampling signal;

and the voltage sampling unit is used for sampling the power grid signal to acquire a voltage signal in the sampling signal.

6. The electric energy metering terminal of claim 1, wherein the isolation module comprises:

the signal amplification unit is connected with the sampling module and is used for amplifying the sampling signal;

and the signal isolation unit is connected with the signal amplification unit and used for isolating the amplified sampling signal.

7. The electric energy metering terminal of claim 6, wherein the isolation module further comprises:

and the driving unit is connected with the signal isolation unit and the analog-to-digital conversion module, is used for realizing impedance matching between the isolation module and the analog-to-digital conversion module, and is used for driving the analog-to-digital conversion module.

8. An electrical service system, the electrical service system comprising:

the electric energy metering terminal of any one of claims 1 to 7, which is used for acquiring the electric energy and electricity utilization information of a user;

the charging module is in communication connection with the electric energy metering terminal and is used for charging according to the electric energy of the user;

and the electric power service platform is in communication connection with the electric energy metering terminal and is used for generating a service scheme of the user according to the power utilization information of the user.

9. An electric energy metering method applied to the electric energy metering terminal according to any one of claims 1 to 7, the electric energy metering method comprising:

sampling a power grid signal to obtain a sampling signal, wherein the sampling signal comprises a voltage signal and a current signal;

isolating a voltage signal and a current signal in the sampling signal;

carrying out analog-to-digital conversion on the isolated sampling signals;

and acquiring the electricity utilization information of the user according to the sampling signal after the analog-to-digital conversion, and sending the electricity utilization information of the user to an electric power service platform.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that: the computer program, when executed by a processor, implements the power metering method of claim 8.

Technical Field

The present invention relates to a measuring apparatus, and more particularly, to an electric energy measuring terminal, method, power service system, and medium.

Background

With the development of the ecosystem of the internet of things, a power company hopes that a metering instrument provided for a customer can meet the requirement of the existing power system on demand side management, and can provide value-added services for the customer through the ecosystem of the internet of things. However, the inventor finds that, in practical applications, the existing electric energy metering terminal can only obtain the power consumption information of the user to charge for the power company, but cannot provide enough power consumption information of the user for the electric power service platform, and therefore, the electric power service platform is difficult to provide value-added services for the user according to the data provided by the electric energy metering terminal.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an energy metering terminal, an energy metering method, an electricity service system and an electricity service medium, which are used to solve the problem that the energy metering terminal in the prior art cannot provide sufficient electricity consumption information for users of the electricity service platform.

To achieve the above and other related objects, a first aspect of the present invention provides an electric energy metering terminal, including: the sampling module is used for sampling the power grid signal to obtain a sampling signal, and the sampling signal comprises a voltage signal and a current signal; the electric energy metering module is connected with the sampling module and used for acquiring the electric energy of the user according to the sampling signal; the isolation module is connected with the sampling module and used for isolating a voltage signal and a current signal in the sampling signal; the analog-to-digital conversion module is connected with the isolation module and is used for performing analog-to-digital conversion on the isolated sampling signals; and the preprocessing module is connected with the analog-to-digital conversion module and used for preprocessing the sampling signal after the analog-to-digital conversion to acquire the power utilization information of the user and sending the power utilization information of the user to the power service platform.

In an embodiment of the first aspect, the preprocessing module performs load identification according to a waveform of the analog-to-digital converted sampling signal; the electricity consumption information of the user includes a result of the load identification.

In an embodiment of the first aspect, the preprocessing module obtains the power quality of the user according to the sampling signal after the analog-to-digital conversion; the electricity utilization information of the user comprises the power quality of the user.

In an embodiment of the first aspect, the preprocessing module obtains a time characteristic of a power consumption condition of a user according to the sampling signal after the analog-to-digital conversion; the electricity consumption information of the user includes the time characteristic.

In an embodiment of the first aspect, the sampling module includes: the current sampling unit is used for sampling the power grid signal to acquire a current signal in the sampling signal; and the voltage sampling unit is used for sampling the power grid signal to acquire a voltage signal in the sampling signal.

In an embodiment of the first aspect, the isolation module includes: the signal amplification unit is connected with the sampling module and is used for amplifying the sampling signal; and the signal isolation unit is connected with the signal amplification unit and used for isolating the amplified sampling signal.

In an embodiment of the first aspect, the isolation module further includes: and the driving unit is connected with the signal isolation unit and the analog-to-digital conversion module, is used for realizing impedance matching between the isolation module and the analog-to-digital conversion module, and is used for driving the analog-to-digital conversion module.

A second aspect of the present invention provides an electric power service system, including the electric energy metering terminal of any one of the first aspect of the present invention, configured to obtain electric energy and electricity consumption information of a user; the charging module is in communication connection with the electric energy metering terminal and is used for charging according to the electric energy of the user; and the electric power service platform is in communication connection with the electric energy metering terminal and is used for generating a service scheme of the user according to the power utilization information of the user.

A third aspect of the present invention provides an electric energy metering method applied to the electric energy metering terminal according to any one of the first aspect of the present invention, the electric energy metering method including: sampling a power grid signal to obtain a sampling signal, wherein the sampling signal comprises a voltage signal and a current signal; isolating a voltage signal and a current signal in the sampling signal; carrying out analog-to-digital conversion on the isolated sampling signals; and acquiring the electricity utilization information of the user according to the sampling signal after the analog-to-digital conversion, and sending the electricity utilization information of the user to an electric power service platform.

A fourth aspect of the present invention provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method of metering electrical energy according to the third aspect of the present invention.

As described above, the technical solution of the electric energy metering terminal, the electric energy metering method, the electric power service system, and the medium of the present invention has the following beneficial effects:

the electric energy metering terminal can sample a power grid signal to obtain a sampling signal, obtains the electricity utilization information of a user by carrying out operations such as isolation, analog-to-digital conversion and preprocessing on the sampling signal, and sends the electricity utilization information of the user to the electric power service platform. Therefore, the electric energy metering terminal can provide the electricity utilization information of the user for the electric power service platform while acquiring the electric energy of the user, so that the electric power service platform can provide personalized value-added services for the user according to the electricity utilization information.

Drawings

Fig. 1 is a schematic structural diagram of an electric energy metering terminal according to an embodiment of the present invention.

Fig. 2A is a circuit diagram of a current sampling unit of the electric energy metering terminal according to an embodiment of the present invention.

Fig. 2B is a circuit diagram of a voltage sampling unit of the electric energy metering terminal according to an embodiment of the present invention.

Fig. 3A is a circuit diagram of an amplifying unit of the electric energy metering terminal according to an embodiment of the invention.

Fig. 3B is a circuit diagram of an isolation unit of the electric energy metering terminal according to an embodiment of the present invention.

Fig. 3C is a circuit diagram of a driving unit of the electric energy metering terminal according to an embodiment of the invention.

Fig. 4 is a flowchart illustrating an embodiment of the method for measuring electric energy according to the present invention.

Description of the element reference numerals

1 electric energy metering terminal

11 sampling module

12 electric energy metering module

13 isolating module

14A/D conversion module

15 preprocessing module

21 shunting copper sheet

22 low-pass filter circuit

S11-S14

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.

It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, number and proportion of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated. Moreover, in this document, relational terms such as "first," "second," and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

The existing electric energy metering terminal can only obtain the electricity consumption information of a user to charge for an electric power company, but cannot provide enough electricity consumption information of the user for an electric power service platform, so that the electric power service platform is difficult to provide value-added service for the user according to data provided by the electric energy metering terminal. Aiming at the problem, the invention provides an electric energy metering terminal which can sample a power grid signal to obtain a sampling signal, obtain the electricity utilization information of a user by carrying out operations such as isolation, analog-to-digital conversion and preprocessing on the sampling signal, and send the electricity utilization information of the user to an electric power service platform. Therefore, the electric energy metering terminal can provide enough electricity utilization information of the user for the electric power service platform while acquiring the electric energy of the user, so that the electric power service platform provides personalized value-added service for the user according to the electricity utilization information.

Referring to fig. 1, in an embodiment of the present invention, the electric energy metering terminal 1 includes a sampling module 11, an electric energy metering module 12, an isolation module 13, an analog-to-digital conversion module 14, and a preprocessing module 15.

The sampling module 11 is configured to sample a power grid signal to obtain a sampling signal, where the sampling signal includes a voltage signal and a current signal. Particularly, when the power grid signal is a three-phase four-wire power frequency ac signal, the sampling signal includes three voltage signals and three current signals, and at this time, the sampling module 11 may be implemented by using three voltage sampling sensors and three current sampling sensors.

The electric energy metering module 12 is connected with the sampling module 11 and is used for acquiring electric energy of a user according to the sampling signal. The unit of the electric energy of the user is kilowatt-hour, the electric energy metering module 12 may obtain the electric energy of the user according to the current and the voltage of the sampling signal, and may also obtain the electric energy in other manners, which is not limited herein. Preferably, the electric energy metering module 12 is connected to a meter reading and charging system of an electric power company in an RS-485 manner, so as to support services such as meter reading and charging of the electric power company.

The isolation module 13 is connected to the sampling module 11, and configured to isolate a voltage signal and a current signal in the sampling signal, so that reference points of the signals in the analog-to-digital conversion module 14 and the preprocessing module 15 meet actual requirements. Specifically, the reference point of the sampling signal obtained from the power grid is often high, which is not beneficial to subsequent further processing and may cause a safety hazard, in this embodiment, the isolation module 13 may isolate one side of the sampling module 11 from one side of the analog-to-digital conversion module 14, so that one side of the analog-to-digital conversion module 14 may adopt a relatively low reference point, which is beneficial to signal processing and does not have a safety hazard.

The analog-to-digital conversion module 14 is connected to the isolation module 13, and is configured to perform analog-to-digital conversion on the isolated sampling signal. Optionally, the analog-to-digital conversion module 14 is implemented by using a six-way high-speed ADC module built in the Azure Sphere internet of things module of microsoft.

The preprocessing module 15 is connected to the analog-to-digital conversion module 14, and is configured to preprocess the analog-to-digital converted sampling signal to obtain power consumption information of a user, and send the power consumption information of the user to a power service platform. Optionally, the preprocessing module 15 is implemented based on an Azure Sphere internet of things module of microsoft. The preprocessing module 15 performs a primary and simple data processing on the sampling signal, and the acquired power consumption information of the user is primary and simple information, for example, the preprocessing module 15 may roughly classify the user according to the sampling signal so as to acquire a rough category of the user. The power service platform, such as microsoft Azure Sphere cloud platform, further processes the power utilization information of the user to obtain deeper and more detailed information, so as to provide personalized customized service for the user. Optionally, the electric energy metering terminal is provided with an Azure Sphere cloud data interface so as to realize data communication with the Azure Sphere cloud platform.

Optionally, the preprocessing module performs load identification according to the waveform of the sampling signal after the analog-to-digital conversion to obtain a load type of the user, for example, the electrical appliance used by the user in a certain period can be obtained by the load identification as a refrigerator, a television, a microwave oven, or the like. The electricity utilization information of the user comprises the result of the load identification, namely the load type of the user is contained. Specifically, the preprocessing module stores different load types and waveforms corresponding to the load types in advance; when the preprocessing module acquires the sampling signal after the analog-to-digital conversion, the waveform of the sampling signal is matched with a pre-stored waveform so as to acquire a matched waveform which is the same as or similar to the waveform of the sampling signal, and then the load type of the user is acquired according to the load type corresponding to the matched waveform.

Optionally, the preprocessing module obtains the power quality of the user according to the sampling signal after the analog-to-digital conversion, and the power consumption information of the user includes the power quality of the user. Specifically, the preprocessing module may obtain the power quality of the user according to the voltage, the frequency, the waveform and the like of the analog-to-digital converted sampling signal, where the power quality of the user includes voltage quality, current quality and/or power quality. Preferably, the electricity consumption information of the user further includes power quality problems existing in the power grid, such as: deviations in voltage, current or frequency that result in a fault or improper operation of the consumer, voltage fluctuations and flicker, three-phase imbalance, transient or transient over-voltages, waveform distortion (harmonics), voltage sags, interruptions, transients, and power supply continuity, among others.

Optionally, the preprocessing module acquires a time characteristic of a power consumption condition of a user according to the sampling signal after the analog-to-digital conversion; the electricity consumption information of the user includes the time characteristic. The time characteristics are, for example, the change relationship of the power consumption of the user with time, the distribution of the power consumption of the user in different periods, and the like.

As can be known from the above description, the electric energy metering terminal in this embodiment can sample a power grid signal to obtain a sampling signal, obtain the power consumption information of a user by performing operations such as isolation, analog-to-digital conversion, and preprocessing on the sampling signal, and send the power consumption information of the user to an electric power service platform. Therefore, the electric energy metering terminal can provide enough electricity utilization information of the user for the electric power service platform while acquiring the electric energy of the user, so that the electric power service platform provides personalized value-added service for the user according to the electricity utilization information.

In the whole electric power service system, the electric energy metering terminal is closer to a user, on one hand, the electric energy metering terminal can preprocess a sampling signal, and the preprocessing work is usually realized by an electric power service platform in the traditional scheme, so that the electric energy metering terminal can reduce the data processing amount of the electric power service platform; on the other hand, the embodiment combines the collection of the user electric energy and the collection of the user electric information in one electric energy metering terminal for realization, thereby facilitating the actual operation. In addition, the electric energy metering terminal performs primary and simple data processing on the sampling signal, so that the electric energy metering terminal does not need to have strong data processing capacity, the cost of the electric energy metering terminal is reduced, and the electric energy metering terminal is convenient to popularize and apply in practice.

In an embodiment of the invention, the sampling signal includes a current sampling unit and a voltage sampling unit. The current sampling unit is used for sampling a power grid signal to obtain a current signal in the sampling signal, and the voltage sampling unit is used for sampling the power grid signal to obtain a voltage signal in the sampling signal. Particularly, when the power grid signal is a three-phase four-wire power frequency alternating current signal, the sampling signal includes three voltage signals and three current signals, and correspondingly, the sampling module includes three current sampling units and three voltage sampling units.

Fig. 2A is a circuit diagram of a current sampling unit according to an embodiment of the present invention. Specifically, the current sampling unit comprises a shunt copper sheet 21 and a low-pass filter circuit 22; the sampling point 2 and the sampling point 3 of the shunt copper sheet 21 are made of special alloy, and the special alloy is manganese copper alloy. In a specific application, the power grid signal flows in through the input point 1 of the shunt copper sheet 21 and flows out from the output point 4. And current sampling is carried out between the sampling point 2 and the sampling point 3, and one path of current signal in the sampling signals can be obtained. The low-pass filter circuit 22 is used for filtering out interference signals so as to improve the accuracy of current sampling.

Fig. 2B is a circuit diagram of the voltage sampling unit according to the embodiment. In this example, the voltage sampling unit is a resistor voltage dividing circuit, the power grid signal flows into the voltage sampling unit through an input point AC _ N, and voltage sampling is performed at a sampling point V2P _ a to obtain one path of voltage signal in the sampling signal; the resistor RA25 is a small resistor.

It should be noted that fig. 2A and fig. 2B are only circuit diagrams of the current sampling unit and the voltage sampling unit, and in a specific application, other circuits may also be used to implement the functions of the current sampling unit and the voltage sampling unit, which is not limited herein.

In an embodiment of the invention, the isolation module includes a signal amplification unit and a signal isolation unit. The input end of the signal amplification unit is connected with the sampling module and used for amplifying the sampling signal. Referring to fig. 3A, a circuit diagram of the signal amplification unit in one embodiment is shown. The signal amplifying unit comprises an amplifying chip U4, and the sampling signal flows into a pin 5 of the amplifying chip U4 after passing through a resistor R4, is output by a pin 6 of the amplifying chip U4 and enters a signal isolating unit. It should be noted that both the voltage signal and the current signal in the sampling signal can be amplified by the signal amplifying unit.

The signal isolation unit is connected with the output end of the signal amplification unit and used for isolating the amplified sampling signal. Fig. 3B is a circuit diagram of the signal amplifying unit in an embodiment. The signal amplification unit comprises an isolation chip U7, and the amplified sampling signal flows into a pin 12 of the isolation chip U7 through a resistor R7, then flows out from a pin 7 of the isolation chip U7 and is output through a resistor R8.

Optionally, the isolation module further includes a driving unit. The driving unit is connected with the signal isolation unit and the analog-to-digital conversion module, and is used for realizing impedance matching between the isolation module and the analog-to-digital conversion module and driving the analog-to-digital conversion module. Fig. 3C is a circuit diagram of the driving unit in one embodiment. The driving unit comprises a driving chip U13, and the sampling signal is output from the isolation unit and then reaches a pin 3 of the driving chip U13, flows out from a pin 1 of the driving chip U13 and then reaches the analog-to-digital conversion module through a resistor R9.

Based on the description of the electric energy metering terminal, the invention also provides an electric power service system. In an embodiment of the present invention, the power service system includes the power metering terminal of the present invention, configured to obtain power and power consumption information of a user; and the charging module is in communication connection with the electric energy metering terminal and is used for performing charging according to the electric energy of a user, and the charging module and the electric energy metering terminal can be connected through an RS485 network, for example. The electric power service platform is connected with the electric energy metering terminal and used for generating a personalized service scheme of a user according to the electricity utilization information of the user, and the electric power service platform and the electric energy metering terminal can be connected through a WIFI network, for example. The power service platform is, for example, an Azure Sphere platform of microsoft. In addition, the electric power service platform can be in communication connection with electronic equipment such as a mobile phone and a computer of a user, so that richer value-added services are provided for the user.

In this embodiment, the electric energy metering terminal is configured to obtain electric energy of a user and send the electric energy to the charging module, so that the charging module can implement a charging function. The electric energy metering terminal is further used for sampling the power grid signal to obtain a sampling signal, and performing preliminary processing on the sampling signal so as to obtain the approximate electricity utilization information of the user, for example, the electric energy metering terminal can realize the approximate classification of the user according to the sampling signal; the electric power service platform has a powerful data processing function, so that the approximate electricity utilization information of the user can be deeply analyzed and processed, and personalized service is provided for the user.

Based on the above description of the electric energy metering terminal, the present invention also provides an electric energy metering method, which can be implemented by using the electric energy metering terminal shown in fig. 1. Referring to fig. 4, in an embodiment of the present invention, the electric energy metering method includes:

and S11, sampling the power grid signal to obtain a sampling signal, wherein the sampling signal comprises a voltage signal and a current signal.

And S12, isolating the voltage signal and the current signal in the sampling signal.

And S13, performing analog-to-digital conversion on the isolated sampling signal.

And S14, acquiring the electricity utilization information of the user according to the sampling signal after the analog-to-digital conversion, and sending the electricity utilization information of the user to an electric power service platform.

Based on the above description of the electric energy and the metering method, the present invention also provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the electric energy metering method of the present invention.

The protection scope of the method for metering electric energy according to the present invention is not limited to the execution sequence of the steps illustrated in the embodiment, and all the solutions implemented by the steps addition, subtraction and step replacement in the prior art according to the principles of the present invention are included in the protection scope of the present invention.

According to the above description, the electric energy metering terminal of the invention can sample the power grid signal to obtain the sampling signal, obtain the electricity utilization information of the user by performing operations such as isolation, analog-to-digital conversion and preprocessing on the sampling signal, and send the electricity utilization information of the user to the electric power service platform. Therefore, the electric energy metering terminal can provide enough electricity utilization information of the user for the electric power service platform while acquiring the electric energy of the user, so that the electric power service platform provides personalized value-added service for the user according to the electricity utilization information.

In addition, the invention combines the collection of the electric energy and the electricity utilization information of the user in one electric energy metering terminal for realization, and the electric energy metering terminal has the functions of measuring the electric energy of the user and communicating with the electric power service platform. In addition, the electric energy metering terminal is internally provided with a sampling module, an isolation module, an analog-to-digital conversion module and a preprocessing module, so that the sampling signal can be processed to obtain the electricity utilization information of the user and roughly classify the user, and the electric energy metering terminal has edge calculation functions of signal acquisition, preprocessing and the like. The electric energy metering terminal is provided with a Microsoft Azure Sphere cloud data interface, so that the powerful cloud computing function of the Azure Sphere platform can be utilized to realize extensible functions of user load identification, user side electric energy quality analysis, user electric equipment classification calculation cost estimation and the like.

In conclusion, the present invention effectively overcomes various disadvantages of the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.