FR2554929A1 - METHOD FOR QUICKLY DETERMINING THE VALUE OF ALTERNATIVE POWER OR ALTERNATIVE ENERGY CONSUMED - Google Patents

Abstract

PROCESS FOR THE RAPID DETERMINATION OF THE VALUE OF AN ALTERNATIVE POWER OR OF AN ALTERNATIVE ENERGY CONSUMED, WITH ELIMINATION OF THE ALTERNATIVE 2 O PULSATION ERROR COMPONENT WHICH NORMALLY INCLUDES THE PRODUCT OF THE VOLTAGE BY THE CURRENT CONSTITUTING THE FIRST PRODUCT. THE VOLTAGE AND CURRENT CONSUMED ARE RESPECTIVELY IN PHASES OF AN ANGLE OF (90-A) OR (90A), EACH BY ONE PHASEUR4, 5, THEN MULTIPLIED IN A SECOND MULTIPLIER2 TO FORM A SECOND PRODUCT. THE TWO PRODUCTS ARE FINALLY ADDED BY AN ADDITIONER3 TO ELIMINATE THE ALTERNATIVE COMPONENT OF THE 2O PULSATION ERROR.

Description

The present invention relates to a method for the rapid determination of

  the value of an alternative power or an energy

  alternative consumed by the evaluation of the multiplication

  voltage and current consumption.

  The patent application of the Federal Republic of Germany, published under DE-A-3011060 describes such methods for electricity meters.

  The only difference between a power meter and an electricity meter

  cited is that the latter integrates the instantaneous power in time.

  In the case of the conventional induction meter, this means that the speed of rotation of the moving disk is a measure of the instantaneous power and the number of revolutions, recorded by the totalizer, a measure of the energy consumed. Any electricity meter is

thus simultaneously a power meter.

  The electricity meter and the power meter each have an input for the voltage u (t) and an input for the consumed current i (t), as well as a multiplier which multiplies the two sizes between them to form the product p (t). ) = u (t) .i (t). The multiplier is

  for example the combination of an amplitude modulator "impulse-

  known pause, which delivers a train of pulses whose amplitude is proportional to the current consumed i (t) and whose pulse / pause ratio is proportional to the voltage u (t), and a downstream integrator, which determines the area of the pulse train and therefore the

product value p (t) = u (t) .i (t).

  The operation of a wattmeter is described below using mathematical equations for the case of a power measurement

  active. This description also applies to a measure of

reactive or apparent.

  We have: u (t) = U.cos wt, i (t) = I.cos (mt + f), p (t) = U.cos wt.I.cos (wt +) =! U.I. [cosÈ + cos (2 ut + f)] Po + P1 "cos (2w.t +), P = (1/2) U.I.cos P1 = (1/2) U.I. and

  w = 2 of, with f = 50 Hz, for a mains frequency of 50 Hz.

  U and I are the amplitudes of the AC voltage or of the AC current consumed, the pulsation and the difference of

  phase between the consumed alternating current and the alternating voltage.

  The product p (t) is thus constituted by two terms and equal to the sum of half of the active power U.Icosf sought and

  of the alternative component of the error P1cos (2 wt + q), which pre-

  feels a pulse 2w. This alternative component of the error to

  pulsation 2w is normally negligible in electricity meters.

  cited because its temporal integration is at most equal to the area

  alternation and thus represents for a long period of

  a negligible percentage of the integrated value Po = 1 / 2U.I.

  cos ô, which continues to grow in time.

  The presence of the alternating component of the pulse error 2w is, on the other hand, a significant drawback in the test devices, since each measurement must be completed as quickly as

  possible, so that at the end of the measurement the alternative component

  the error represents a not insignificant percentage of the integrated value P. For an accuracy of 0.01% per

O 4

  For example, the measurement time should be 10.10 ms = 100 seconds, which is much too long for the automatic balancing of a test station. The time of 10 ms represents the value of the alternation

the network voltage.

  The subject of the invention is a method for the determination

  fast and without delay as possible the value of the alternating power

  native or consumed alternative energy, without

  important compared to devices already existing in a test station and without the alternative component of the error at

  2w pulse causes a significant error.

  According to an essential characteristic of the invention, one of the two magnitudes - voltage or current consumed - is out of phase with an angle

  of (90 - a) and the second of an angle (90 + a) with respect to

  even, a being a constant angle; a second product is formed by multiplication of the two out of phase magnitudes; and both products

are added together.

  Other features and advantages of the invention will be

  better understood using the detailed description below of a

  Embodiment and the accompanying drawings in which: FIG. 1 shows the block diagram of a device for measuring an alternating power with cancellation of the alternating component of the pulse error of 2w; FIG. 2 represents the vector diagram of the voltages; and FIG. 3 represents the block diagram of a device comprising three multipliers for the elimination of errors and with cancellation

  of the alternating component of the pulse error of 2w.

  The same references designate identical components on

all the figures.

  The device represented in FIG. 1 comprises a first multiplication

  1, a second multiplier 2, an adder 3, a first

  phase shifter 4 and a second phase shifter 5. A voltage u (t) feeds directly

  first entry of the first multiplier 1 and, through

  the first phase-shifter 4, a first input of the second multi-

  plicateur2. A second voltage u 1 (t), proportional to the current

  consumed i (t), directly feeds a second input of the first multi-

  1 and, through the second phase-shifter 5, a second input of the second multiplier 2. The single output of the multiplier Dremier t and the single output of the second multiplier 2 are

  each connected to an input of the adder 3, the output of which

  the output of the device. u2 (t) is the output voltage of the first phase shifter 4, which produces a phase shift of (90 - a), and u3 (t) the output voltage of the second phase shifter 5, which produces a phase shift of (90 + a). The values of the two phase shifts can also

be permuted.

  FIG. 2 represents the vector diagram of the voltages u (t), u1 (t), u2 (t) and u3 (t), U being the factor of u (t), U1 that of u1 (t), U2 being the factor of u2 (t) and U3 that of u3 (t). The current consumed i (t) and consequently the proportional voltage u1 (t) being out of phase with an angle with respect to the voltage u (t), the same angle is formed by both the vector U and the vector U1 as perpendicular to

  these two vectors U and U1, shown in phantom in FIG.

  The vector U2 forms an angle of (90 - a) with the vector U and pre-

  feels the same length as the latter. The vector U3 forms an angle of (90 + a) with the vector U1 and has the same length as the latter. In FIG. 3, the voltages u (t), u1 (t), u2 (t) and u3 (t) feed three multipliers 6, 7 and 8 via a four-contact switch 9. The single output of each of the three multipliers 6, 7 and 8 is connected to an input of an adder O10

  with three inputs and whose output is the output of the device.

  The four-contact switch 9, having the arms 9a, 8b, 9c and 9d, always operates a combination of only two of the three multipliers, namely the combination 6; 7, 7; 8 or 6; 8. The three multipliers 6, 7 and 8 are for example each the multiplier of a single-phase wattmeter or the three multipliers of a power meter

  or three-phase electricity meter, which comprises, in a known manner, a multi-phase

  plicant per phase. The four-contact switch 9 has three positions, so that each time one of the

  three possible combinations 6; 7, 7; 8 or 6; 8.

  In the first position of the switch 9, the first arm 9a connects the voltage u (t) to the first input of the multiplier 6, the second arm 9b connects the voltage u (t) to the second input of the multiplier 6, the third arm 9c connects the voltage u2 (t) to the first input of the multiplier 7 and the fourth arm 9d connects the voltage

  u3 (t) at the second input of the multiplier 7.

  In the second position of the switch 9, the third and fourth arms 9c and 9d do not connect the voltages u2 (t) and u3 (t) to the inputs of the multiplier 7, but to the corresponding inputs

multiplier 8.

  In the third position of the switch 9, and unlike the connections established on the second position, the first and second arms 9a and 9b do not connect the voltages u (t) and u1 (t) to the inputs of the multiplier 6, maes at the corresponding entries of the

multiplier 7.

  The two multipliers 6; 7, 6, 8 or 7; 8 put into service assume

  with the three-input adder 10 of FIG.

  the two multipliers 1, 2 and the adder 3 in figure 1. We have the following equations: u (t) = U cos wt, i (t) = I cos (wt + t), u1 (t) - ki (t) = k I cos (wt + f) = U1 cos (ut + e), with U] 1 = kI, u2 (t) = U2 cos (wt + 90 - ") with U2 = U and u3 (t) = U3 cos (wt + '+ 90 + a) where U3 = U1 k being a constant, X the network pulsation, t time, at any constant angle and U, I, U1, U2 and U3 l amplitude of

  u (t), i (t), u1 (t), u2 (t), u3 (t) respectively.

  The first multiplier 1 of FIG. 1 forms a first product: p (t) = u (t) .u1 (t) = U cos t (kI) cos (wt + Y) = (k / 2) UI [cosdf + cos (2 wt + Y)] The second multiplier 2 of Figure 1 forms a second product: p1 (t) = u2 (t) .u3 (t) = U cos (wt + 90 - a). (KI) cos ( wt + <+ 90 + a) = (k / 2) UI [cos (f + 2 a) + cos (2 t + 180 + e)] = (k / 2) UI [cos (t + 2 a) cos ( 2 wt + f)] The adder 3 of FIG. 3 forms the sum: p (t) + p1 (t) = u (t) .u1l (t) + u2 (t) .U3 (t) = (k / 2) UI [cos t + cos (2 t + Y) + cos (Y + 2 a) - cos (2 t + e) 1 = (k / 2) UI [cos q + cos (+ + 2 a)]

  Two values of 0 are of particular interest.

  - c <, 0 that is to say that u2 (t) is phase shifted by 90 with respect to u (t) and u3 (t) is out of phase by 90 with respect to u1 (t) and consequently

also at i (t).

  In this case: p (t) + p1 (t) = (k / 2) UI (cosf + cos?) = K UI cosY = 2.k Po

  Po = (1/2) U.I cosf representing the active power to be measured.

  -. + 2 ≤ 90, that is to say that the phase-shifted voltage u2 (t) is according to FIG. 2 out of phase with respect to the voltage u3 (t)

also out of phase.

6 2554929

  In this case p (t) + p1 (t) = (k / 2) .U.I (cos'D + cos 90)

= (k / 2) .U.I cos L = k.P0.

  - In both cases, the sum [p (t) + p1 (t) 1 is thus proportion-

  to the active power to be measured U.I cos e and not erroneous

  because the alternating component of pulsed error 2 w does not

  keep away. In other words, the precise value of the

  active mode is either available instantaneously and continuously or, in the case of the pulse-pause amplitude modulation method, independent of the integration time, so that short integration times and short durations

  measurement are possible without increasing the inaccuracy

measurement.

  The assembly according to Figure 1 requires additional equipment.

  However, the test devices already contain the two

  -cateurs 1 and 2, because most often the adjustment is simul-

  at least two wattmeters or single-phase electricity meters or at least one wattmeter or three-phase electricity meter, the adder 3 or 10 being furthermore available in this connection.

last case.

  The assembly according to FIG. 3 can be used for adjusting a three-phase power meter or electricity meter and also makes it possible to determine errors. The multipliers 6, 7 and 8 are in this case those already in the wattmeters or electricity meters. The three multipliers for example each have an unknown error X, Y or Z. Three measurements are made successively to form three equations with three unknowns X, Y and Z, the switch 9 to four

  contacts putting into operation for each measure a different combination

  2 of 3 single phase wattmeters or 2 of the 3 phases of a

  wattmeter or three-phase electricity meter.

  Assuming that the assembly is supplied by the same voltages u (t), u1 (t), u2 (t) and u3 (t) for the three measurements, and consequently the products p (t) and p1 (t) ) have the same values, we have the following three equations: - measure 1: p (t) + p1 (t) + X + Y = MW1 (1) - measure 2: p (t) + pl (t) + X + Z = MW2 (2) and - measure 3: p (t) + p1 (t) + Y + Z = MW3 (3) MW1, MW2 and MW3 representing the three measured values at the output of the device. The sum [p (t) + p1 (t-)] is equal to 2.k.P0 for a = 0 Qu to k. P0 in the case o t + 2a = 90, P being determined for example oo using a power meter or a calibrated reference electricity meter. The following hypothesis is made below for the sake of simplicity: k = 1 for a = 0 and (k / 2) = 1 for the case o + 2 a =

   . We then have p (t) + p1 (t) = Po0 in both cases.

  Errors X, Y and Z are the only three unknowns of the system

of equations (1), (2) and (3).

  The following notations allow an easy transformation of the three equations (1), (2) and (3): A1 = MW1 - p (t) - p1 (t) = MW1 - P o A2 = MW2 p (t) - p1 ( t) = MW2 - P and A3 = MW3 - p (t) - p1 (t) = MW3 - Po The system of equations (1), (2) and (3) can be written as follows:

X + Y = A1 (4)

X + Z = A2 (5) and

Y + Z = A3 (6)

  These three equations make it possible to mathematically determine the values of the three unknowns X, Y and Z, which are then used to

  the adjustment of the three multipliers.

  The out of phase quantities U2 and U3, as well as the quantities not

  phase-shifted U and U1 or proportional currents can be

  totally or partially by signal generators.

  Of course, various modifications may be made by those skilled in the art to the principle and to the devices which have just been described as non-limiting examples, without leaving

of the scope of the invention.

8 2554929

Claims (8)

claims   1. Method for the rapid determination of the value of a power   alternative or alternative energy consumed, by   tion of the multiplication product of the voltage and of the current consumed, said method being characterized in that one of the two magnitudes voltage or current consumed, is out of phase with an angle of   (90 - a), and the second by an angle of (90 + a) with respect to them   the same, a being a constant angle; a second product is formed   by multiplication of the two out of phase magnitudes; and finally the two O10 duits are added.   2. Method according to claim 1, characterized in that the angular value a is chosen so that the two out-of-phase magnitudes   finally show a phase shift of 90 between them.   3. Method according to claim 1, characterized in that the value angular a is zero.   4. Process according to any one of claims 1 to 3, characterized   in that both products are each formed by means of a   multiplier (6, 7, 8), the two multipliers being those containing   naked in an electricity meter.   Method according to claim 4, characterized in that for   the adjustment of three single-phase wattmeters, each with a   pliquer (6, 7, 8) and a common adder (3), three measurements are made to form three equations with three unknowns; then the values of the three unknowns are determined using the three equations, the unknowns each representing an error (X, Y, Z) of the three wattmeters and a different combination of two of the three wattmeters being used during each measurement   for the formation of both products.   6. Method according to claim 5, characterized in that the three single-phase wattmeters are each a phase of a wattmeter or a three-phase electricity meter.   7. Method according to claim 1, characterized in that the large   phase shifters and non-phase magnitudes can be delivered   totally or partially by signal generators.   8. Device for implementing the method-according to claim 1 9 2554929   characterized in that it comprises a first multiplier (1), a second multiplier (z, an adder (3), a first phase shifter (4) and a second phase shifter (5), the two magnitudes - voltage and consumed current are applied on the one hand directly to the inputs of the first multiplier (1) and on the other hand, each via one of the two phase shifters (4, 5), to the inputs of the second multiplier (2), and the outputs of the two multipliers are   each connected to an input of the adder (3).   9.Dispositif for the implementation of the method according to claim 5, characterized in that it comprises three multipliers (6, 7, 8), a four-contact switch (9) and a three-input adder (10), the cabling of the three-position switch (9) and the three multipliers (6, 7, 8) being realized in such a way that only a combination of two of the three multipliers (6, 7, 8) is in operation, the non-phase-shifted magnitudes being applied to the inputs of the first multiplier and the out-of-phase magnitudes to the inputs of the second multiplier; the three multipliers (6, 7, 8) each etched to an input of the adder 10 to three entries.