WO2021132867A1

WO2021132867A1 - Electronic power meter having function of automatic correction and minimization of tolerance of measurement circuit element

Info

Publication number: WO2021132867A1
Application number: PCT/KR2020/015177
Authority: WO
Inventors: 김응석; 김경태; 윤민영
Original assignee: 김응석
Priority date: 2019-12-24
Filing date: 2020-11-03
Publication date: 2021-07-01
Also published as: KR102092065B1

Abstract

The present invention proposes an electronic power meter capable of minimizing a tolerance of a passive element used in a measurement unit and minimizing errors caused by elements of the measurement unit, other ICs, or the like. The proposed electronic power meter comprises: a voltage sensing unit connected to a first line and a second line of a power supply side; a current sensing unit connected between a load side and the first line of the power supply side; a reference power generation unit for applying a reference voltage and a reference current in an automatic correction mode to the voltage sensing unit and the current sensing unit; and a calculation unit for causing reference power to be applied instead of AC power of the power supply side to the voltage sensing unit and the current sensing unit in the automatic correction mode, and calculating weights for all input ranges of the electronic power meter on the basis of values measured in the voltage sensing unit and the current sensing unit.

Description

Electronic watt-hour meter with minimization of tolerance of measuring circuit element and automatic correction function

The present invention relates to an electronic watt-hour meter, and more particularly, to an electronic watt-hour meter having a tolerance minimization and automatic correction function of a measurement circuit element.

Recently, power grid systems such as smart grids and microgrids have been highlighted due to energy shortage and environmental problems.

In such a power grid system, a precise watt-hour meter is required to measure the amount of power generated from the distributed power source owned by the user and trade the remaining surplus power.

In the existing electronic watt-hour meter, an error in A/D conversion data occurs for each device due to the tolerance of the element in the measurement unit and the error caused by the IC.

Due to these errors, a process of manually calibrating each device is performed to minimize errors due to devices and ICs so that measurements can be performed.

The present invention has been proposed to solve the above conventional problems, and the purpose of the present invention is to provide an electronic watt-hour meter that can minimize the tolerance of passive elements used in the measurement unit and minimize errors caused by the elements or other ICs of the measurement unit. have.

In order to achieve the above object, an electronic watt-hour meter according to a preferred embodiment of the present invention includes a voltage sensing unit connected to the first line and the second line of the power supply side; a current sensing unit connected between the first line of the power supply side and the load side; a reference power generator for applying a measurement source voltage in an automatic correction mode to the voltage sensing unit and the current sensing unit; And in the automatic calibration mode, the reference power is applied to the voltage sensing unit and the current sensing unit instead of the AC power on the power side, and based on the measured values by the voltage sensing unit and the current sensing unit, an electronic watt-hour meter and a calculation unit that calculates weights for all input ranges.

In the automatic correction mode, the operation unit may operate a switch that cuts off the AC power or a switch that selects and receives inputs of the AC power and the reference power.

The reference power may be a reference power in a range having a maximum value of 1/N of the maximum power input of the watt-hour meter.

The voltage sensing unit may measure the voltage n times with respect to the reference voltage, and transmit n measurement values of each measurement source voltage to the operation unit.

The current sensing unit may measure the current n times with respect to the reference voltage, and transmit n measurement values of each measurement source voltage to the calculating unit.

The calculation unit stores the measured values of the voltage sensing unit and the current sensing unit measured based on the reference voltage and the reference current in the voltage sensing unit and the current sensing unit, and calculates a function for the weight based on the stored data And, by using the calculated weight function to calculate the weight for all ranges of the input range of the electronic watt-hour meter, it is possible to apply the weight to the measurement range up to the maximum value of the input range of the electronic watt-hour meter.

The voltage sensing unit and the current sensing unit may include one or more of a resistor, an inductor, and a capacitor.

The resistor can be configured by connecting n series of n parallel resistors formed by connecting n resistors in parallel, or by connecting n resistors having n times the resistance value in parallel to minimize the resistance tolerance.

The inductor may be configured by connecting n parallel inductor bundles configured by connecting n inductors in parallel in series or by connecting n inductors having an inductor value of n times in parallel to minimize the tolerance of the inductor.

The capacitor can be configured by connecting n series inductor bundles formed by connecting n capacitors in series in parallel, or by connecting n capacitors having n times the capacitor value in series to minimize the tolerance of the capacitors.

According to the present invention having such a configuration, by using the electronic watt-hour meter having the tolerance minimization and automatic correction function of the measurement circuit element, the tolerance of the element of the measurement circuit can be minimized, and the measurement value due to the error of the element and the IC, etc. By minimizing the error, the measurement precision can be improved.

1 is a block diagram of an electronic watt-hour meter according to an embodiment of the present invention.

2 and 3 are flowcharts for explaining the automatic calibration process of the electronic watt-hour meter according to an embodiment of the present invention.

4 is a view showing an explanatory example of the weight in the description of the automatic calibration process of the electronic watt-hour meter according to an embodiment of the present invention.

5 to 10 are examples of circuit configurations for minimizing tolerances of passive elements used in a voltage sensing unit and a current sensing unit.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail.

However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this 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 art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate the overall understanding, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

A switch capable of cutting off commercial power by using an element such as a diode in a form in which the reference power generating unit 16 is always connected and configured to prevent the commercial power input from being reversely input to the reference power generating unit 16 It is configured such that the input voltage of commercial power and the output voltage of the reference power generator 16 can be selected and received.

For example, the electronic watt-hour meter according to an embodiment of the present invention can measure the wattage of a single-phase two-wire commercial AC circuit. The single-phase two-wire commercial AC circuit supplied from the power source to the load may include a live line (L) and a neutral (ground line) (N).

The electronic watt-hour meter according to an embodiment of the present invention includes a power circuit unit 10, a voltage sensing unit 12, a current sensing unit 14, a reference power generating unit 16, a display unit 18, a first data communication unit ( 20 ), a second data communication unit 22 , a time setting unit 24 , a memory storage unit 26 , and an external sensor input unit 28 , and an operation unit 30 .

The power circuit unit 10 may receive power-side commercial power and supply operating power to various electronic components constituting the corresponding electronic watt-hour meter.

In other words, the power circuit unit 10 may receive alternating current (AC) power from the power source, rectify it, convert it into direct current (DC) power required by various electronic components inside the electronic watt-hour meter, and then output it.

In particular, the power circuit unit 10 receives AC power from the power supply side and converts it into DC power as required by the voltage sensing unit 12, the current sensing unit 14, the reference power generating unit 16, and the calculating unit 30. DC operating power can be applied.

The voltage sensing unit 12 may measure an input voltage.

In other words, the voltage sensing unit 12 senses the input AC voltage, converts it to a voltage level that the A/D converter inside the calculating unit 30 can receive, and provides it to the calculating unit 30 . That is, the voltage sensing unit 12 is connected to the input terminal of the amplifier after converting the voltage on the power supply side to a voltage level that can be input to the A/D converter inside the operation unit 30 using a divider resistor, and the amplifier output is output to the operation unit ( 30) is connected to the internal A/D converter.

The voltage sensing unit 12 cuts off the voltage input from the power supply side with an element such as a switch when the automatic correction function is performed. In other words, when the operation unit 30 sends the reference voltage generation signal of the reference power generation unit 16, the output of the reference power generation unit 16 and the voltage sensing unit 12 are always connected from the power source side to the device such as a switch. cut off the voltage input of , and receive the voltage output from the reference power generator 16 . When the automatic correction function is not used, the reference power generating unit 16 and the voltage sensing unit 12 are connected, but the protection element is configured so that commercial power is not reversely input to the output of the reference power generating unit 16, and The output of the power generation unit 16 is not generated.

Alternatively, the voltage sensing unit 12 blocks the voltage reception from the power supply side by the voltage sensing unit input selection signal of the calculating unit 30 when the automatic correction function is performed, and the voltage output from the reference power generation unit 16 is performed. get input

That is, the voltage sensing unit 12 cannot receive an AC voltage from the power supply side when the automatic correction function is performed, and inputs a reference voltage having a maximum value of 1/N of the input maximum voltage from the reference power generation unit 16 and measure the voltage. Here, the above-described reference voltage may be, for example, a magnitude obtained by 1/N of the maximum input voltage of the watt-hour meter as the maximum value, and may be varied within the range. As a result, the voltage sensing unit 12 repeatedly measures the voltage over n times (eg, the number of times measured by dividing the range of the reference voltage) with respect to the reference voltage, and each measured value (ie, n measured values) ) to the operation unit 30 .

The current sensing unit 14 may measure a current.

In other words, the current sensing unit 14 senses the input current, converts it to a voltage level that the A/D converter inside the calculating unit 30 can receive, and provides it to the calculating unit 30 . That is, the current sensing unit 14 may include a current sensor including a current transformer, a Hall sensor, a shunt resistor, and the like, and an amplifier to measure the current.

In particular, the current sensing unit 14 is connected between the live line L on the power supply side and the load side.

The current sensing unit 14 cuts off the current input from the power supply side with an element such as a switch when the automatic correction function is performed. In other words, when the calculation unit 30 sends the reference current generation signal of the reference power generation unit 16, the output of the reference power generation unit 16 and the current sensing unit 14 are always connected from the power source side to the device such as a switch. cut off the current input and receive the current output from the reference power generator 16 . When the automatic correction function is not used, the reference power generating unit 16 and the current sensing unit 14 are connected, but the protection element is configured so that commercial power is not reversely input to the output of the reference power generating unit 16, and The output of the power generation unit 16 is not generated.

Alternatively, when the automatic correction function is performed, the input selection element blocks current reception from the power supply side by the control signal of the operation unit 30 (ie, the current sensing unit input selection signal) and inputs the current output from the reference power generation unit 16 . receive

That is, the current sensing unit 14 cannot receive current from the power source when the automatic correction function is performed, and measures the reference current having a maximum value of 1/N of the maximum input current from the reference power generating unit 16. . Here, the above-described reference current may be, for example, a maximum value obtained by 1/N of the input maximum current of the watt-hour meter, and may be varied within the range. As a result, the current sensing unit 14 repeatedly measures the current for n times (eg, the number of times measured by dividing the range of the reference current) with respect to the input reference current, and each measured value (ie, n measurements) value) to the operation unit 30 .

While the above-described automatic correction function is being performed, the load is removed and it is performed in a no-load state.

The reference power generator 16 may generate a precise reference power (ie, a reference voltage and a reference current) used for the automatic correction function.

In other words, the reference power generating unit 16 is a precise reference power (ie, the reference voltage) used in the automatic correction function to minimize errors caused by internal elements and ICs of the voltage sensing unit 12 and the current sensing unit 14 . , reference current) may be generated and provided to the voltage sensing unit 12 and the current sensing unit 14 .

For example, the reference power generating unit 16 is always connected to the voltage sensing unit 16 and the current sensing unit 14 to prevent the commercial power input from being input in the reverse direction of the reference voltage generating unit 16 . A reference voltage and input in a range having a maximum value of 1/N of the input maximum voltage by a control signal (ie, a reference voltage generation signal, a reference current generation signal) from the operation unit 30 in a circuit configuration A reference current having a maximum value of 1/N of the maximum current may be sequentially generated and provided to the voltage sensing unit 12 and the current sensing unit 14 .

As another example, the reference voltage generator 16 may select and receive commercial power and the output of the reference voltage generator 16 using an input selection element.

That is, the reference power generation unit 16 sequentially generates an AC or DC measurement source voltage that is increased to a certain width by a control signal (ie, a reference voltage generation signal, a reference current generation signal) from the operation unit 30 , It may be provided to the voltage sensing unit 12 and the current sensing unit 14 . For example, the reference voltage may have a maximum value obtained by 1/N of the input maximum voltage of the watt-hour meter and may be varied within the range. The reference current has the maximum value of 1/N of the input maximum current of the watt-hour meter and can be varied within the range. As a result, the reference power generation unit 16 generates a reference voltage and a reference current in a range having a maximum value of 1/N of the maximum input voltage and maximum current of the watt-hour meter to generate the voltage sensing unit 12 and the current sensing unit ( 14) can be provided to

The display unit 18 may display various data measured by the voltage sensing unit 12 , the current sensing unit 14 , and the calculating unit 30 .

In other words, the display unit 18 displays the measured power through a display device such as an LCD, so that the user can visually confirm it. In addition, if necessary, the voltage, current, time, etc. may be displayed on the display unit 18 using a button.

The first data communication unit 20 makes it possible to check the measurement data through Ethernet communication.

In other words, the first data communication unit 20 operates as a web server through Ethernet communication to check real-time measurement data.

The second data communication unit 22 allows the measurement data to be confirmed through serial communication.

In other words, the second data communication unit 22 enables real-time confirmation of data measured through serial communication.

The time setting unit 24 may set real-time time information.

In other words, the time setting unit 24 may set time information using a Real Time Clock (RTC) for real time time information.

The memory storage unit 26 stores measurement data and stores data for operating as a web server.

In other words, the memory storage unit 26 stores the measured power data and data such as voltage and current and maintains the measured data during a power failure. Also, the memory storage unit 26 stores data for operating as a web server. Because it stores the first data communication unit 20, it is possible to operate as a web server.

The external sensor input unit 28 is connected to various external sensors (eg, sensors such as temperature and humidity, carbon dioxide, illuminance, radiation, fine dust, etc.).

The external sensor input unit 28 receives and confirms measurement data from the corresponding external sensor.

The calculator 30 may calculate power by converting the AC voltage measured by the voltage sensing unit 12 and the current measured by the current sensing unit 14 into digital signals through the A/D converter, respectively.

In other words, the calculating unit 30 may convert the output voltages of the voltage sensing unit 12 and the current sensing unit 14 into digital values using an internal A/D converter to calculate power.

Then, the calculation unit 30 receives the time information of the time setting unit 24 and the measurement value of the sensor connected to the external sensor input unit 28 and transmits it to the outside through the display unit 18 and the

data communication units

20 and 22 . do. In addition, the operation unit 30 stores the measured data in the memory storage unit 26 to preserve the existing measurement data in the event of a power failure or abnormality, thereby controlling the overall operation of the device.

In particular, when the operation unit 30 performs the automatic correction function (that is, when the automatic correction mode is turned on), the reference power generator 16 is always connected after removing the load using a device such as a diode. It is configured to prevent the power input from being reversely input to the reference power generator 16, so that a switch capable of cutting off commercial power operates or cuts off the power input from the power source using an input selection element, and the reference power generator 16 ) to connect the output power to the voltage sensing unit 12 and the current sensing unit 14 .

Accordingly, the calculation unit 30 sets the maximum value of the input maximum voltage and maximum current of the watt-hour meter to the voltage sensing unit 12 and the current sensing unit 14 under the automatic correction mode as the maximum value. , by providing a reference current, the voltage sensing unit 12 and the current sensing unit 14 store the data of the measurement value repeatedly measured over n times (eg, the number of times measured by dividing the range of the reference power) in the memory storage unit ( 26) is saved. Then, the calculator 30 calculates a function for the weight based on the stored data. Then, the calculator 30 calculates a weight for the entire range of the electronic watt-hour meter input by using the calculated weight function. Then, the calculating unit 30 applies a weight to the measurement range up to the maximum value of the input range of the electronic watt-hour meter.

2 and 3 are flowcharts for explaining an automatic calibration process of an electronic watt-hour meter according to an embodiment of the present invention, and FIG. 4 is a description of weights in the automatic calibration process description of an electronic watt-hour meter according to an embodiment of the present invention It is a drawing showing an example.

In order to perform the automatic correction function, it is necessary to prevent the reference power from being provided to the voltage sensing unit 12 and the current sensing unit 14 together, and the input of the voltage sensing unit 12 and the current sensing unit 14 is " To check the measured value when it is 0 (zero)", the load side must be disconnected.

Accordingly, the calculating unit 30 first removes the load (S10).

Thereafter, power is supplied to the voltage sensing unit 12 and the current sensing unit 14 (S12). In this case, the arithmetic unit 30 generates a reference voltage generation signal or a reference voltage input selection signal to cut off the AC power from the power source and supply the output of the reference power generation unit 16 to the voltage sensing unit 12 ( S14). Accordingly, it is configured to prevent the commercial power input from being reversely input to the reference power generating unit 16 by using an element such as a diode in a form that is always connected to the reference power generating unit 16 to cut off the commercial power. A possible switch operates or cuts off the power input from the power supply side using an input selection element, and connects the output power of the reference power generator 16 to supply the voltage sensing unit 12 (S16). Then, the operation unit 30 generates a reference current generation signal or a reference current input selection signal to cut off the AC power from the power source and supply the output of the reference power generation unit 16 to the current sensing unit 14 (S18). ).

Accordingly, it is configured to prevent the commercial power input from being reversely input to the reference power generating unit 16 by using an element such as a diode in a form that is always connected to the reference power generating unit 16 to cut off the commercial power. A possible switch operates or cuts off the power input from the power source using an input selection element, connects the output power of the reference power generator 16, and supplies it to the current sensing unit 14 (S20).

Thereafter, the reference power generation unit 16 varies and outputs the reference voltage and the reference current in the range in which the input maximum voltage of the watt-hour meter and the maximum current 1/N necessary to perform the automatic correction function are the maximum values (S22) .

Accordingly, the voltage sensing unit 12 and the current sensing unit 14 sense the input reference voltage and the reference current, and transmit corresponding measured values to the operation unit 30 . The voltage and current sensing by the voltage sensing unit 12 and the current sensing unit 14 is repeated n times (eg, the number of times measured by dividing the range of the reference power source) for the corresponding measurement source voltage.

After the reference power (reference voltage, reference current) becomes equal to the input maximum voltage and maximum current 1/N (“Yes” in S24 and “Yes” in S26), the calculating unit 30 repeats n times. The measured value for each reference voltage and the measured value for each reference current are stored in the memory storage unit 26 (S28, S30).

Then, the calculating unit 30 calculates a function for the weight (size of the reference power/measured value) based on the measured value and the data about the size of the reference power stored in the meantime (S32, S34). Here, the function for the weight may be a function of the reference voltage for the measured value and a function of the reference current for the measured value.

Then, the weight for the entire range of the watt-hour meter input is calculated using the calculated weight function. 4, the calculation unit 30 uses a reference power of 1/N size of the entire input range that the electronic watt-hour meter can receive, and 1/N of the maximum value of the total input that can be input. The reference power is changed in the range of the size and sequentially input to the voltage sensing unit 12 and the current sensing unit 14, and the size and measured value of the reference power at the time of input (ie, the measured value measured n times) will be saved Then, the calculating unit 30 calculates the relational expression for the reference power and the measured value through the stored data, and calculates the weight for the range before (all) the electronic watt-hour meter input based on the calculated relational expression of the input range of the electronic watt-hour meter. A weight is applied to the measurement range up to the maximum value. Relational expressions can be obtained by methods such as the proportional expression method, the least squares method, and the gradient method.

In Y=f(x) described in FIG. 4 , Y is the input value, x is the measured value, and f(x) is the weight.

Then, the calculating unit 30 cuts off the reference voltage generation signal (or the reference voltage input selection signal) and blocks the reference current generation signal (or the reference current input selection signal) (S36 and S38). Thereby, the automatic correction mode is canceled.

When the automatic calibration mode is released, it is configured to prevent the commercial power input from being reversely input to the reference power generator 16 by using an element such as a diode in a form that is always connected to the reference power generator 16. A switch capable of cutting off commercial power releases the block or cuts off the output power of the reference power generator 16 using an input selection element, and connects the power input from the power source to the voltage sensing unit 12 and the current sensing unit ( 14) (S40, S42).

5 to 10 are examples of methods for minimizing tolerances of passive elements configured of a voltage sensing unit and a current sensing unit.

5 and 6 are examples of a configuration method by minimizing the tolerance of the resistance used in the voltage sensing unit 12 or the current sensing unit 14 or other measurement circuits. 5, by connecting n resistors having a resistance value of R in parallel and connecting n parallel resistors having a value of R/n in series (R1, R2, ... Rn) to a resistance of R make up

Alternatively, as shown in FIG. 6 , n resistors increased by n times the resistance of the R value are connected in parallel. The error of the total combined resistance Rt converges to the average value of the errors (e1, e2, ... ei) of each resistor (

) As the number of parallel connections increases, the probability of minimizing the error of the total combined resistance increases.

7 to 10 are configuration examples of a circuit used by minimizing the tolerance between the capacitor and the inductor as shown in FIGS. 5 and 6 .

As described above, as the number of resistors and inductors connected in parallel and capacitors connected in series increases, the probability of minimizing the tolerance between the combined resistance, the combined inductance, and the combined capacitance increases.

Accordingly, in order to minimize the tolerance of the measurement circuit elements, as in the above example, the number of the elements connected in parallel or in series may be appropriately increased.

As described above, the best embodiment has been disclosed in the drawings and the specification. Although specific terms are used herein, they are only used for the purpose of describing the present invention, and are not used to limit the meaning or the scope of the present invention described in the claims. Therefore, it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the true technical protection scope of the present invention should be defined by the technical spirit of the appended claims.

Claims

a voltage sensing unit connected to the first and second lines of the power source;

a current sensing unit connected between the first line of the power supply side and the load side;

a reference power generator for applying a reference voltage and a reference current in an automatic correction mode to the voltage sensing unit and the current sensing unit; and

In the automatic correction mode, the reference power is applied to the voltage sensing unit and the current sensing unit instead of the AC power on the power side, and an electronic watt-hour meter is input based on the measured values from the voltage sensing unit and the current sensing unit An electronic watt-hour meter comprising a; a calculator that calculates weights for all ranges.
The method according to claim 1,

The calculation unit,

In the automatic calibration mode, a switch capable of cutting off commercial power by using elements such as diodes in a form that is always connected to the reference power generating unit to prevent the commercial power input from being reversely input to the reference power generating unit An electronic watt-hour meter, characterized in that the power input from the power source is cut off using an input selection element or the output power of the reference power generator is connected to be supplied to the voltage sensing unit and the current sensing unit.
The method according to claim 1,

The output of the reference power generation unit is an electronic watt-hour meter, characterized in that the input by changing the reference voltage and the reference power in a range of 1/N of the maximum input value that can be input.
4. The method according to claim 3,

The voltage sensing unit measures the voltage n times with respect to the input reference voltage, and transmits the n measured values to the operation unit.
5. The method according to claim 4,

The current sensing unit measures the current n times with respect to the input reference current, and transmits the n measured values to the calculating unit.
6. The method of claim 5,

The calculating unit stores the measured values of the voltage sensing unit and the current sensing unit measured based on the reference voltage and the reference current applied to the voltage sensing unit and the current sensing unit, and functions for a weight based on the stored data , calculates weights for all ranges of the electronic watt-hour meter input using the calculated weight function, and applies the weight to the measurement range up to the maximum value of the input range of the electronic watt-hour meter.
The method according to claim 1,

The voltage sensing unit and the current sensing unit,

An electronic watt-hour meter comprising at least one of a resistor, an inductor, and a capacitor.
8. The method of claim 7,

The resistor is configured by connecting n series of n parallel resistors formed by connecting n resistors in parallel, or by connecting n resistors of n times the resistance value in parallel to minimize the resistance tolerance. Electronic power meter.
8. The method of claim 7,

The inductor is configured by connecting n parallel inductor bundles formed by connecting n inductors in parallel in series, or by connecting n inductors having n times the inductor value in parallel to minimize the tolerance of the inductor. Electronic power meter.
8. The method of claim 7,

The capacitor is configured by connecting n series inductor bundles configured by connecting n capacitors in series in parallel, or by connecting n capacitors of n times the capacitor value in series to minimize the tolerance of the capacitors, characterized in that Electronic power meter.