JPS58139074A - Ac measuring apparatus - Google Patents

Abstract

PURPOSE:To enable a direct measurement with an arithmetic controller eliminating the necessity of any analog instrument by computing an instantaneous power portion at each sampling in such a manner tht the number of sampling is so determined as to be zero pulsated components containing the instantaneous power portions. CONSTITUTION:Voltage and current information is provided in a digital value from an analog-digital converter 17 to match a sampling cycle and memorized and updated sequentially with a shift register 21. The contents of each register of the shift register 21 are taken as measured value proportional to an effective power VIcostheta via a multiplier 22, an adder 23 and a divider 24 and the like. Thus, the sampling and the computation made at an appropriate cycle enables the measurement of an effective power in such a manner as to zero the pulsated components during the addition thereof. This eliminates any analog instrument thereby enables a direct measurement with an arithmetic controller such as microcomputer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alternating current measuring device that measures an alternating current amount v4 of alternating current power or the like from voltage and current signals detected from a power system.

Variable current metering 1 includes, for example, the system voltage extracted from a variable RIkK or a variable RIkK, dII5I! Power is measured from analog to log storage AC power needles, but in order to measure various types of AC needles such as rickshaws and reactive power, it is necessary to use dedicated analog instruments for each type of measurement. I need. Also, total −j
When transmitting to the central master station, as shown in FIG. It is conceivable to transmit it to the central side by the device slave station 3, or convert it into an analog-to-digital converter using the needle sub-quantity of the AC fill E force meter, use it as an integrated input of the microcomputer, and transmit it from the microcomputer to the central side. Both require analog instruments to measure the amount of alternating current.

The purpose of the invention is to eliminate the need for analog instruments and voltage.

, 4EI51e's detection signal is used to provide the AC needle #1 device, which is designed so that the foot can be measured directly by a paralysis device such as a microcomputer.

FIG. 2 is an overall configuration diagram showing an embodiment of the present invention. The voltage v1 of the grid rIti is taken out as a voltage signal at the measurement signal level by an auxiliary transformer 610° and a current transformer 11, respectively, and these voltage and current signals are passed through a filter 12. I
Only the fundamental wave component is extracted by IK, and then extracted as sample value information by sample and hold circuits 14 and 15.

Sample and hold circuit 14. The voltage and current signal sample values of II are time-divisionally analog-to-digital converted by a multiplexer 16. The converted output of the converter 11 is taken in as calculation information to an arithmetic and control device 111 such as a mital computer. The calculation control device IS calculates the desired received current measurement amount from digital information or analog 4G information corresponding to voltage and current 1, and further calculates the total #1 value from the central master station according to -16 tatami. and send it to the control point. The pulse generator 519 is a sample hold circuit.

Provides necessary mutually synchronized clock pulses to various parts such as a multiplexer and an analog-to-digital 5-converter.

The arithmetic control 111!111B calculates the voltage v a shown in FIG.
For miK, its sample value vl, V2 * ”h
The digital values of e"" and 11°12*1ms... are taken in sequentially, and the instantaneous power v1 is added for each sampling of these digital values, and the number of additions n and the sampling period are appropriately determined in the calculation formula. As a result, the calculation result is 9! A value V proportional to fi power is obtained. This will be explained below.

First, if the detection voltage V and electric power fii are expressed as a general formula, then the above formula I'l1 becomes k as shown in the following formula 131.

The third term on the right side of equation (3) is 5n1=cos(2ωt1+#)+cos(2ωt1+
2ωΔ゛r+su+・・・・・・・・・+ coa(2c
a+t1+2a+(n-1)ΔT+-#) -...
...141, and if we further set 2ω11+#=α,
Equation (4) is 8, )1:Cogα+cos(α+2ωΔT
)+...+cos(α+2ω(g-1)ΔT)...
... (51) Here, if ωΔT and n are appropriately Integer) ・・・・・・(6)6JjT= @Oo, n
= 3 k (// ) ””i71ωΔT=3
0°* n = s k (#) ---
---181, it becomes 8Ω2;0. Above (6
) formula, in formula 161, nz4()(
zl), one mountain type & end 8n2” eO1α(1+cos11f+cosS8G
'+cos840")-81nα(5inllG"
+ain311G@+5inI40”)=coaα(
1-1+1-1)-sin α(0+0+0>= 0 Therefore, by setting the number of additions n and the sampling period ΔT to 1, the second term of the equation 131 becomes 0, and S#I becomes the first It becomes only the term swa = n VI co
s a """ (9), which is proportional to the active power and becomes a value.

#44 diagram is calculation 1! The hardware configuration of the arithmetic circuit based on formula (11) in IIIflJ118 is shown below.

The analog-to-digital converter 17 provides digital voltage and current information in accordance with the above-mentioned sampling period, and this information is divided into four voltage information and current information by the distributor 20, and the image information is the sample value 16. A shift register 21iC, which divides the data into blocks, updates the memory of each application. The contents of the valley register of the shift register 21 are the voltage and electric fi values at the same sampling time, respectively, and the multiplier 22
Multiplied by ! ! The results of each operation of the calculator 22 are
They are added by an adder 23, and an output proportional to the calculation by the above-mentioned m formula is taken out. The output of this adder 23 is divided by the number of samples to be added by a divider 24, and the result is obtained as a needle subvalue proportional to the active power VIco's#.

Therefore, in the present invention, by combining the temporary power at an appropriate period and zeroing it out, the active power is calculated so that the outside of the instantaneous power consists of a DC component and a pulsating component, and the pulsating component becomes a fathom when added. In order to measure it, it can be measured by calculating the voltage and current samples 11 without relying on the magnetic pressure of the foot measurement and the electric power meter from the four waterfalls Anag Shinman to the Anasog meter. Furthermore, when using digital quantities for measurement, the measurement can be made by utilizing the free time of the computing unit mat of the m device on the remote monitoring side.

In addition, although the case where active power is measured is shown in the implementation column, power factor and reactive power planning can be performed using voltage and current information as well as measured power information for Wc4 other than this power. The ms diagram has a configuration in which reactive power information is transferred using measured nine-dimensional effective power. The active power P obtained by division 824 is calculated by square P1 by multiplication @28. - 10,000, the voltage and current information of the shift register 21 are added by the adders 26 and 27, respectively, the result of the calculation is adjusted by the coefficient with the active power P by the coefficient units 28 and 29, and the image information is added by the multiplier 30. This calculation result is squared by a multiplier 31, 22 is subtracted by a subtracter 32, and this calculation result is subjected to a square root calculation by a square root calculation unit 33. The reactive power Q is extracted.

Also, division! The output Pt of the multiplier 24 and the output v of the multiplier 30 can be reduced by 1lll and the power factor COa # can be improved.

cog #=P/VI

[Brief Description of the Drawings] Fig. 1 is a diagram showing the conventional power needle #l1fI position, the lNz diagram is an overall configuration diagram showing the -'Am example of the power invention, and Fig. 3 is a diagram showing the sampling information in Fig. 2. FIG. 4 is a waveform diagram for explanation; FIG. 4 is a corporal punishment circuit diagram of the calculation side device 18 in FIG. 142; and FIG. be. 18...Arithmetic side-device, 1-...Pulse generator, 2
0...Distribution! , 21...Shift register, 3...
Multiplier, 23... Adder, 24... Divider, ms,
Go. 31... Multiplier, 2m, 2'l... Adder, 18.
19...Coefficient unit, 32...Subtractor, 1t...Square root calculator.

Claims (1)

[Claims] - - The instantaneous values of the analog detection signals of the power IE and current of the 2g system are sampled at a predetermined period, and the instantaneous power of each sample is calculated by multiplying each sample value of voltage and current. , Add the temporary power to the number of samples at which the pulse included in the temporary power becomes zero, and use the addition result to obtain a light value proportional to the active power of the AC system. Measuring device. 12+ Sample the temporary values of the voltage and current analog detection signals of the AC system at a predetermined period, calculate the instantaneous power for each pull/pull by multiplying each sample value of voltage and current, and add this instantaneous power. The number of samples at which the pulsation component included in the instantaneous power component becomes zero is set as the key addition result by 1ff.
Obtain a value proportional to the active power of the ifi system, add each sample value of the above voltage and current, multiply the result of adding the sample values of voltage and current, and add the second value of this multiplication value to the above active power. A receiving current measuring device that performs square root calculation by subtracting the square value of the proportional value, and the result of this square root calculation is superior to the value proportional to the reactive power of the AC system. 1; Sampling the temporary values of the voltage and current analog detection signals of the AC system at a predetermined period, calculating the temporary power for each sample by multiplying each sample value of voltage and current, and adding this instantaneous power. The number of samples at which the pulsation component included in the Kdr instantaneous power component becomes zero is the addition result of 9! Obtain the value proportional to the active power of the system, and calculate the above voltage and tIIR.
, respectively, and multiply by the voltage and current sample value addition results, this multiplication value is proportional to the active power of the AC system, and the value is subtracted by -1, and the current transformation is applied to this division result. A current change measuring device characterized by obtaining a value proportional to the power of the system.