KR20140037505A - Power measurement equipment - Google Patents

Abstract

The present invention comprises: a calculation unit for calculating the magnitude of a voltage signal and the magnitude of a current signal according to harmonics and phase information on a voltage signal and a current signal by analyzing frequency characteristics after receiving three-phase voltage and three-phase current to detect the positive-phase-sequence components of each phase, and for calculating effective electric power, reactive power, and a telephone influence factor (TIF); and an electric energy display unit for displaying the effective electric power, the reactive power, and the TIF. [Reference numerals] (10,20) A/D converter; (30) Calculation unit; (50) Alarming unit; (AA) Active power; (BB) Reactive power

Description

Integrated power meter {POWER MEASUREMENT EQUIPMENT}

The present invention relates to an integrated power meter, and more particularly, to an integrated power meter that calculates active power, reactive power, and harmonics using a field programmable gate array (FPGA).

In general, the integrated wattmeter uses the Aragon's disc principle, which uses a method in which a mechanical rotating plate is turned in proportion to the amount of current flowing to measure power. Such integrated power meters have a high durability and low cost, while harmonics are not measured.

Recently, a simple and inexpensive electronic wattmeter has been developed, and a smart wattmeter is being developed to automatically check the electricity consumption through the Internet.

In general, an integrated power meter should have a low price. This is because the cost of installing the integrated power meter increases greatly if the price of the integrated power meter to be installed in each home is too high. In addition, the integrated wattmeter shall be subject to differential rates for electrical installations (loads) which adversely affect the system. However, it is true that the conventional totalizer does not have any function other than the advantage of low price.

On the other hand, power can be divided into active power and reactive power. Until now, Korea has maintained a policy of including only active power in the electricity bill, but in some countries, there is a method of including reactive power in the electricity bill. The reason is that the reactive power is related to the voltage, so for the power equipment with the malicious load, the company operating and managing the power grid installs a reactive power supply separately to maintain the voltage. Because it includes.

In addition, as the use of power electronic equipment increases, the harmonics generated in power electronic equipment degrade the power quality of the power system, and in severe cases, cause instability in the power system. As a result, companies operating and managing grids incur additional costs of installing additional filters in the system for reactive power to maintain power quality.

In addition, until now, due to the performance and cost of the integrated power meter, a method of incorporating harmonics into the used power has not been developed, and thus harmonics are not included in the power.

Background art related to the present invention is a multi-function all-electric integrated power meter for remote meter reading of Republic of Korea Patent Publication No. 10-1990-0013311 (1990.09.05).

An object of the present invention is to provide an integrated power meter that measures active power, reactive power, and harmonics by using a field programmable gate array (FPGA).

Another object of the present invention is to reduce the manufacturing and production costs of integrated power meters.

Another object of the present invention is to measure the harmonics in response to the increasing use of power electronic equipment to identify additional costs for coping with power quality deterioration and power system instability caused by the use of power electronic equipment. It is.

Still another object of the present invention is to warn harmonics caused by the use of power electronic equipment using an integrated power meter, and to predict communication noise due to such harmonics.

The integrated power meter according to an aspect of the present invention receives the three-phase voltage and three-phase current, detects the normal portion of each phase, and then analyzes the frequency characteristics to determine the magnitude of the voltage signal and the magnitude of the current signal, the voltage signal, and the current signal for each harmonic. A calculation unit configured to calculate active power, reactive power, and telephone influence factor (TIF) after calculating phase information of the power supply; And an amount of power display that displays the active power, the reactive power, and the TIF.

The calculation unit of the present invention is characterized in that the field programmable gate array (FPGA).

The calculation unit of the present invention receives a three-phase voltage and a three-phase current input unit for detecting the normal portion of each phase; A Fast Fourier Transform (FFT) calculator for analyzing the frequency characteristics of the normal components of each phase and extracting the magnitude of the voltage signal, the magnitude of the current signal, and the phase information of the voltage signal and the current signal for each harmonic; An active power calculator configured to calculate the active power by using the magnitude of the voltage signal and the magnitude of the current signal and the phase information of the voltage signal and the current signal; A reactive power calculator configured to calculate the reactive power by using the magnitude of the voltage signal and the magnitude of the current signal and the phase information of the voltage signal and the current signal; A TIF calculator configured to calculate the TIF by applying a C-message weight to the voltage signal; And a TIF comparator for outputting a comparison result by comparing the TIF calculated by the TIF calculator with a preset reference value.

According to the comparison result of the TIF comparator of the present invention is characterized in that it further comprises a warning unit for warning the communication noise.

The TIF calculator of the present invention is characterized in that the C-message weights set for the frequencies of the voltage signals are applied to each of the voltage signals and then summed.

The active power calculation unit of the present invention is characterized in that after calculating the active power for each harmonic by using the magnitude of the voltage signal and the magnitude of the current signal and the phase information of the voltage signal and the current signal, and adds.

The reactive power calculation unit of the present invention is characterized in that after calculating the reactive power for each harmonic by using the magnitude of the voltage signal, the magnitude of the current signal and the phase information of the voltage signal and the current signal for each harmonic and sums them.

The apparatus may further include a rate calculator configured to calculate a power rate for the active power, the reactive power, and the TIF of the present invention.

The fee calculation unit of the present invention is characterized in that the power charge for the TIF is added according to the size of the TIF.

It further comprises a charge display unit for displaying the active power of the present invention, the reactive power and the power charge for the TIF.

The present invention measures field power, reactive power, and harmonics using a field programmable gate array (FPGA).

In addition, the present invention reduces the manufacturing and production cost of integrated power meter using the FPGA.

In addition, the present invention can identify additional costs for coping with power quality deterioration and power system instability caused by the increasing use of power electronic equipment, for example, the cost of installing filters and system disturbance prevention devices. Make sure

In addition, the present invention warns the generation of harmonics according to the use of power electronic equipment, and predicts the communication noise due to harmonics.

1 is a block diagram of an integrated power meter according to a first embodiment of the present invention.
FIG. 2 is a block diagram illustrating the calculation unit of FIG. 1.
FIG. 3 is a block diagram illustrating a steady state detector and an FFT calculator of FIG. 1.
FIG. 4 is a diagram illustrating a calculation process of the normal part detector of FIG. 3.
FIG. 5 is a block diagram illustrating the FFT calculator of FIG. 3.
6 is a diagram illustrating a calculation process of an active power calculator of FIG. 2.
7 is a diagram illustrating a calculation process of the reactive power calculator of FIG. 2.
8 is a block diagram illustrating a TIF detector of FIG. 2.
9 is a block diagram of an integrated power meter according to a second embodiment of the present invention.
FIG. 10 is a block diagram illustrating the calculation unit of FIG. 9.

Hereinafter will be described in detail with reference to the accompanying drawings, the agitation accumulator according to an embodiment of the present invention. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

1 is a block diagram of an integrated power meter according to a first embodiment of the present invention.

As shown in FIG. 1, the integrated power meter according to the first embodiment of the present invention includes a three-phase current and a three-phase current from an I3φ CT (Current Transformer) for detecting a three-phase current and a V3φ VT (Voltage Transformer) for detecting a three-phase voltage. Receives the phase voltage, analyzes the frequency characteristics of the normal components of each phase from the input three-phase current and three-phase voltage to obtain the magnitude of the voltage signal, the magnitude of the current signal and the phase information of the voltage signal and the current signal for each harmonic, A calculation unit 30 and a calculation unit for calculating active power, reactive power, and telephone influence factor (TIF) using the magnitude of the voltage signal and the magnitude of the current signal and the phase information of the voltage signal and the current signal acquired for each harmonic; The power amount display unit 40 for displaying the active power, the reactive power, and the TIF calculated in 30), and a warning unit 50 for warning the communication failure when the TIF is greater than or equal to a preset TIF reference value.

Here, TIF is the square root of the sum of squared multiplied by the square root of the effective value of all sinusoidal (sine wave) components (base wave and its harmonics) with respect to the voltage or current waveform of the power system. It is rain.

The A / D converters 10 and 20 convert analog signals input from CT and VT into digital signals and input them to the calculator 30 so that the calculator 30 calculates the active power, the reactive power, and the TIF. .

In particular, the calculator 30 is implemented as a field programmable gate array (FPGA). FPGAs are non-memory semiconductor devices that can be programmed and used to meet the needs of users. Fast FPGAs can perform relatively fast computational fast Fourier transforms (FFTs) and program them as needed. In addition, since the calculator 30 is implemented as an FPGA, the production and manufacturing cost of the integrated power meter is greatly reduced.

FIG. 2 is a block diagram illustrating the calculation unit of FIG. 1, FIG. 3 is a block diagram illustrating the normal point detector and the FFT calculator of FIG. 1, and FIG. 4 illustrates a calculation process of the normal detector of FIG. 3. 5 is a block diagram of the FFT calculator of FIG. 3.

The calculation unit 30 receives the three-phase voltage and the three-phase current, and analyzes the frequency characteristics of the normal components of each phase detected by the normal component detector 31 and the normal component detector 31 to detect the normal components of each phase. The magnitude of the voltage signal and the magnitude of the current signal, the magnitude of the voltage signal and the magnitude of the current signal, and the magnitude and voltage signal of the voltage signal extracted for each harmonic by the FFT calculator 32 and the FFT calculator 32 that extract phase information of the voltage signal and the current signal. And the active power calculator 33 and the FFT calculator 32 that calculate the active power using phase information of the current signal and the magnitude of the voltage signal, the magnitude of the current signal, and the phase information of the voltage signal and the current signal. Reactive power calculation unit 34 for calculating the reactive power using the TFT calculation unit 32 includes a TIF calculation unit 35 for calculating the TIF by applying the C-message weight to the voltage signal extracted for each harmonic.

First, as shown in FIG. 3, the normal portion detector 31 receives a three-phase voltage and a three-phase current from an A / D converter, detects the three-phase normal portion, and inputs the same to the FFT calculator 32.

That is, as shown in FIG. 4, the normal part detector 31 calculates the normal parts V _pa , V _pb and V _pc of the three-phase voltage, which is represented by Equation 1 below.

이며, V_pa,V_pb,V_pc는 3상 전원(V_a,V_b,V_c)의 정상분이다. 이때, 1/j(j=0,···,k-1)을 표현하기 위해서는 90°의 위상 지연 필터인 전역필터가 사용된다.here,

V _pa , V _pb , and V _pc are normal portions of three-phase power sources (V _a , V _b , V _c ). At this time, in order to express 1 / j (j = 0, ..., k-1), a global filter which is a phase delay filter of 90 degrees is used.

In addition, since the normal part of a three-phase current is the same as calculating the normal part of the three-phase voltage mentioned above, the detailed description is abbreviate | omitted here.

The FFT calculator 32 analyzes the frequency characteristics of the normal component of the three-phase voltage and the normal component of the three-phase voltage input from the normal component detector 31 to determine the magnitude of the voltage signal, the magnitude of the current signal, the voltage signal, and the current signal for each harmonic. Extract phase information of.

The FFT calculating unit 32 is for analyzing the frequency characteristics of the actual measurement signal and is shown as shown in FIG. The FFT calculator 32 is based on a Discrete Fourier Transform (DFT), and performs an operation as shown in Equation 2 below.

는 샘플된 실제 측정신호의 주파수 대역을 N등분으로 나누고 이중 k 번째 주파수 구간을 나타낸다. Referring to Equation 2,

Denotes the k-th frequency range, dividing the frequency band of the sampled actual measurement signal by N equals.

Therefore, the FFT calculator 32 selects and processes only necessary signals among sampling signals by using Equation (2). The FFT operation unit 32 performs frequency-specific analysis of the fundamental signal to the 40th harmonic through the FFT operation on the voltage signal and the current signal, and the magnitude of the voltage signal, the magnitude of the current signal, and the magnitude of the voltage signal and the current signal for each harmonic signal. Compute phase information.

As described above, after the FFT calculating unit 32 calculates the magnitude of the voltage signal and the magnitude of the current signal and the phase information of the voltage signal and the current signal for each harmonic signal, the magnitude of the voltage signal and the magnitude of the current signal extracted for each harmonic signal And phase information of the voltage signal and the current signal are input to the active power calculator 33, the reactive power calculator 34, and the TIF calculator 35.

The active power calculating unit 33 calculates and adds the active powers by using the magnitude of the voltage signal and the magnitude of the current signal and the phase information of the voltage signal and the current signal for each harmonic in the FFT calculator 32.

6 is a diagram illustrating a calculation process of an active power calculator of FIG. 2.

Referring to FIG. 6, the active power calculation unit 33 calculates the active power by applying the magnitude of the voltage signal, the magnitude of the current signal, and the phase information of the voltage signal and the current signal extracted for each harmonic to Equation 3 below. .

Here, P _n is the n-order effective power, V _n is the magnitude of n-order voltage, I _n is the magnitude of n-order current, and (θ _Vn -θ _In ) is the phase information of voltage and current.

Referring to FIG. 6, the magnitudes of the voltages and currents of each order are input by a multiplier, and the phase currents of the voltages are input by an adder, and then the cosine function is multiplied, multiplied by the result of multiplying the magnitudes of the orders of magnitude and the current. By integrating with the integrator, the active powers of the harmonics of the order P ₁ , P ₂ , ..., P ₄₀ are calculated. This process is performed from the fundamental frequency to the 40th harmonic.

When the active power calculation unit 33 calculates the active power of the 40th harmonic signal at the fundamental frequency through the above process, the active power of the 40th harmonic signal is summed at these fundamental frequencies to finally calculate the total active power.

In this case, since the effective power calculation unit 33 measures not only the fundamental wave but also the amount of power due to harmonics, the effective power calculation unit 33 can calculate more accurate active power and check information on active power for each frequency.

Next, the reactive power calculator 34 calculates and adds the reactive power by using the magnitude of the voltage signal, the magnitude of the current signal, and the phase information of the voltage signal and the current signal for each harmonic in the FFT calculator 32.

7 is a diagram illustrating a calculation process of the reactive power calculator of FIG. 2.

Referring to FIG. 7, the reactive power calculation unit 34 uses the magnitude of the voltage signal, the magnitude of the current signal, and the phase information of the voltage signal and the current signal extracted for each harmonic to calculate the effective power using Equation 4 below. Calculate

Referring to FIG. 7, the magnitudes of the voltages and currents of each order are input by a multiplier, and the phases of the phase currents of the voltages are input by an adder and then multiplied by the sine function, and multiplied by the result of multiplying the magnitudes of the orders of magnitude by the magnitude of the current. By integrating with the integrator, the reactive power (Q ₁ , Q ₂ , ..., Q ₄₀ ) of the harmonics of the order is calculated. This process is performed from the fundamental frequency to the 40th harmonic.

When the reactive power calculator 34 calculates the reactive power of the 40th harmonic signal at the fundamental frequency through the above process, the reactive power calculation unit 34 sums the reactive power of the 40th harmonic signal at these fundamental frequencies and finally calculates the total reactive power.

That is, the reactive power calculator 34 performs the same calculation process as the active power calculator 33 except that the reactive power is calculated using the sine function.

In addition, since the reactive power calculator 34 measures not only the fundamental wave but also the amount of power due to harmonics, the reactive power calculator 34 may calculate more accurate active power and check information on active power for each frequency.

8 is a block diagram illustrating a TIF calculator of FIG. 2.

The TIF calculator 35 calculates a TIF by applying a C-message weight to the magnitude of the voltage signal extracted for each harmonic by the FFT calculator 32.

Here, the C-message represents the degree to which harmonics of the power system cause the communication noise by combining with the harmonic voltages at different weights for each frequency. The weight to be synthesized.

Normally, harmonics generate communication noises in nearby communication lines. The reason for applying C-message weights for each frequency is to consider the response characteristics of frequency bands or communication equipments in which humans respond sensitively to the audible frequency bands, and power signals. This is because the degree of noise generated in the communication line is different for each frequency.

The TIF calculator 35 calculates a TIF through Equation 5 below.

으로써, 가중치를 적용하지 않는 전압 실효치이다.Where f is frequency, K _f is 5000 (F / 1000)) = 5f, P _f is C-message weight, V _f is the effective voltage at frequency f,

This is a voltage rms value without applying a weight.

Referring to FIG. 8, the TIF calculator 35 applies a C-message weight corresponding to each frequency to a voltage signal for each harmonic (V ₁ ,..., V ₄₀ ) measured up to 40th order from the fundamental frequency. Calculate the TIF by summing the result of applying the C-message weight from the wave to the 40th harmonic (V ₁ · C ₁ , ..., V ₄₀ , C ₄₀ ).

In this case, the TIF is a criterion for communication noise, and should be maintained at 15 to 50. Therefore, as shown in FIG. 8, the TIF comparator 36 compares the TIF calculated by the TIF calculator 35 with a preset TIF reference value, for example, 40, to calculate the TIF calculated by the TIF calculator 35. If the preset TIF reference value or more, the alarm unit 50 warns of harmonic generation and communication noise.

Here, the TIF set value is a reference value for alerting the communication noise, and may be variously set according to whether or not communication noise occurs or a power operation policy.

The power amount display unit 40 displays the active power, the reactive power, and the TIF calculated by the calculator 30, and displays the active power, the reactive power, and the TIF, respectively, and displays a liquid crystal display (LCD) or an LED ( Light Emitting Diode) and the like can be employed.

In the first embodiment of the present invention, the calculation of the active power, the reactive power, and the TIF has been described, but an additional power charge for the active power, the reactive power, and the TIF may be calculated.

This will be described with reference to FIGS. 9 and 10.

9 is a block diagram of an integrated power meter according to a second embodiment of the present invention, and FIG. 10 is a block diagram of a calculation unit of FIG.

In the integrated power meter according to the second embodiment of the present invention, the same reference numerals are given to the same parts as the first embodiment, and detailed description thereof will be omitted.

As shown in FIG. 9, the integrated power meter according to the second embodiment of the present invention includes a calculation unit 30, a power amount display unit 40, a warning unit 50, and a charge display unit 60.

As shown in FIG. 10, the calculation unit 30 receives a three-phase voltage and a three-phase current, and detects a normal portion of each phase, and a normal portion detected by the normal portion detector 31. The magnitude of the voltage signal extracted for each harmonic by the FFT calculator 32 and the FFT calculator 32 that extract the magnitude of the voltage signal and the magnitude of the current signal and the phase information of the voltage signal and the current signal by analyzing the frequency characteristics of the minute. And the magnitude of the current signal and the magnitude of the voltage signal extracted for each harmonic by the active power calculation unit 33 and the FFT calculation unit 32 that calculate the active power using the magnitude of the current signal and the phase information of the voltage signal and the current signal. Computing TIF by applying C-message weight to the magnitude of the voltage signal extracted for each harmonic by the reactive power calculator 34 and the FFT calculator 32 that calculates reactive power using phase information of the voltage signal and the current signal. TI F calculation unit 35 and a calculation unit 37 for calculating the power charge for the calculated active power and reactive power and TIF.

The rate calculator 37 calculates the electric power charges for the active power, the reactive power, and the TIF calculated by the active power calculator 33, the reactive power calculator 34, and the TIF calculator 35. The charge calculator 37 includes an active power charge calculator 371, a reactive power charge calculator 372, and a harmonic charge calculator 373.

The active power rate calculation unit 371 calculates the power rate for the active power calculated by the active power calculation unit 33, and the reactive power rate calculation unit 372 calculates the invalidity calculated by the reactive power rate calculation unit 372. The power charge for the power is calculated, and the harmonic charge calculation unit 373 calculates the power charge for the TIF.

In particular, the fee calculator 37 adds a predetermined fee corresponding to the size of the TIF. This is because the harmonic generation rate increases with more electric power facilities. As such, the larger the TIF, the more the electric charge is added, thereby inducing a reduction in the use of electric power equipment.

The fee display unit 60 displays the sum of the active power fee, the reactive power fee, and the harmonic fee calculated by the fee calculation unit 37, or displays them separately. Here, the charge display unit 60 may be a liquid crystal display (LCD), a light emitting diode (LED), a seven-segment, or the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, I will understand. Accordingly, the true scope of the present invention should be determined by the following claims.

10,20: A / D converter 30: calculation unit
31: normal detection unit 32: FFT calculator
33: active power calculator 34: reactive power calculator
35: TIF calculator 36: TIF comparator
37: charge calculator 371: active power charge calculator
372: reactive power charge calculator 373: harmonic charge calculator
40: power amount display unit 50: warning unit
60: fare display unit

Claims (10)

After inputting three-phase voltage and three-phase current, the normal part of each phase is detected, and then the frequency characteristics are analyzed. A calculator configured to calculate reactive power and a telephone influence factor (TIF); And
And a power amount display unit for displaying the active power, the reactive power, and the TIF. The integrated power meter of claim 1, wherein the calculator is a field programmable gate array (FPGA). The method of claim 1, wherein the calculation unit
A normal part detecting unit which receives a three-phase voltage and a three-phase current and detects a normal part of each phase;
A Fast Fourier Transform (FFT) calculator for analyzing the frequency characteristics of the normal components of each phase and extracting the magnitude of the voltage signal, the magnitude of the current signal and the phase information of the voltage signal and the current signal for each harmonic;
An active power calculator configured to calculate the active power by using the magnitude of the voltage signal and the magnitude of the current signal and the phase information of the voltage signal and the current signal;
A reactive power calculator configured to calculate the reactive power by using the magnitude of the voltage signal and the magnitude of the current signal and the phase information of the voltage signal and the current signal;
A TIF calculator configured to calculate the TIF by applying a C-message weight to the voltage signal; And
And a TIF comparator configured to output a comparison result by comparing the TIF calculated by the TIF calculator with a preset reference value. The integrated power meter of claim 3, further comprising a warning unit that warns of communication noise according to a comparison result of the TIF comparator. The method of claim 3, wherein the TIF calculation unit
The integrated power meter, characterized in that after applying the C-message weights set to the frequency of each of the voltage signal applied to each of the voltage signal. The method of claim 3, wherein the active power calculation unit
The integrated power meter, characterized in that by calculating the active power for each harmonic by using the magnitude of the voltage signal, the magnitude of the current signal and the phase information of the voltage signal and the current signal. The method of claim 3, wherein the reactive power calculation unit
An integrated power meter, which calculates and adds reactive power for each harmonic using the magnitude of the voltage signal and the magnitude of the current signal and the phase information of the voltage and current signals for each harmonic. 4. The integrated power meter of claim 3, further comprising a charge calculator configured to calculate power charges for the active power, the reactive power, and the TIF. 10. The integrated power meter of claim 8, wherein the rate calculator further adds a predetermined fee corresponding to the TIF. 10. The integrated power meter of claim 8, further comprising a charge display unit for displaying the active power, the reactive power, and a power charge for the TIF.

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