Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R22/00—Arrangements for measuring time integral of electric power or current, e.g. electricity meters
  • G01R22/06—Arrangements for measuring time integral of electric power or current, e.g. electricity meters by electronic methods
  • G01R22/061—Details of electronic electricity meters
  • G01R22/066—Arrangements for avoiding or indicating fraudulent use

Definitions

• the present invention relates to a method for the determination of illegal connection or tampering of meters of a power line.
• the present invention relates a method which allows to detect any fraud on a power line, or any loads connected to the electrical line without the presence of a counter, and/or individual tampered or malfunctioning counters, by statistical analysis and processing of the measured data, taking into account the equations of power on the line.
• the object of the present invention is to provide a method for the determination of non-technical losses in a power line which solves the problems left open by the prior art.
• An object of the present invention is to provide a method and a system for the determination of tampered or badly working counters and direct sockets, without counter, in a power line, according to the annexed claims, which form an integral part of the present description.
• FIG. 2 shows a detailed flow chart of what is indicated as block C in figure 1 ;
• FIG. 3 shows an example of a system that implements the method of the invention. Detailed description of examples of the invention
• the invention is based on the analysis of data collected on the electrical grid through the usual electricity meters and other line electrical parameters meters (by electricity meters it is understood electronic meters or electric meters).
• electrical line it is to be understood not the whole electrical grid, but a single branch of it.
• the aim of the method is to determine a confidence on the measures of individual counters, and on the assumption of an illegal connection with respect to the measure, deemed reliable, of the total energy on the line, taking into account the energy losses due to the Joule effect.
• the meter normally operates in the following way:
• the power balance of a line cannot be realized, either because of measurement discrepancies for individual counters, or due to illegal connection, which are present on the line and not counted by the individual counters, or for any discrepancy of the dispersions due to the Joule effect compared to what theoretically expected for the line.
• the first of these effects is described by a multiplicative factor, the time-dependent ki(T), relevant to each counter. This proportionality factor is a confidence in the measurements obtained by the /-th counter and is close to 1 when the counter detects the actual power consumption.
• the second effect i.e. illegal connection
• P dir (t)Q(t) wherein Q(t) is the contribution of illegal connection to be estimated in advance.
• the factor P dir (T) is 0 when the illegal connection is absent.
• the change compared to the dispersion provided by the Joule effect is described by a factor dependent on the time Aft), which is equal to d, md in the case that the dispersion is actually the one predicted theoretically. With these corrections, the above equation is rewritten as
• the measures are considered discrete, i.e. carried out in successive instants of time, during which the values P lN of power, entered on the line are measured or consumed by each counter P with respect to the previous instant.
• M the number of measurements taken
• the number of unknown parameters of such a system is N+2 (the N parameters k which are the multipliers of the contribution by the N counters, the parameter P dir related to any illegal connection and the parameter which takes account of the dispersions by Joule effect).
• the thus constructed system is an over-determined system of linear equations if the equations are linearly independent and if M > N + 2.
• the method is statistically more significant when M is bigger than N by approximately an order of magnitude.
• the division of the problem into elementary units, besides providing subsequently a distribution of the parameters, allows, as anticipated, to operate on a piecewise linear system, in which the unknown parameters are to be considered the average values for each single unit of the unknown functions Kj(T), Pdi r ( ) and A(t), better approximating a possible non- constant trend of these parameters.
• the distribution in L smaller dimension problems allows a reduction of the computational costs and an easy implementation of the method by parallel algorithms.
• the quartiles are the values that divide the set into four parts of equal amount, they are five values that mark the 0% ⁇ q,), 25% (q 2 ), 50% (q 3 ), 75% (q 4 ) and 100%) (q 5 ) of the set, q 3 is commonly termed the median, the difference q 4 - q 2 is the interquartile range, which is a measure of the dispersion of the values, and the values q, and q 5 are the minimum and maximum.
• (Gj) S /2 + i corresponds, as defined, to the average value of the measures of the -th counter in relation to the average value of the input power PIN (here S is meant as an even integer, but in general can also be odd, and then one uses (Gj) a with a an integer such that the above relation is selected),
• W (w) is a function defined as a non-decreasing or a function of the sum of the contributions of the first w counters taken in the order defined by (7);
• k' cu is a function of the values of the statistical indicators of k, obtained for each counter, in particular the standard deviation of the median or mean from the ideal value /, or the same mean and median;
• Y(w) is a cost function, increasing in w, for which some simple expressions are (but other expressions are usable with similar effectiveness):
• the function C(w) is highest in w 0 when such a number of counters balances the initial shortfall and does not involve an excessive growth of Y(w). It is here to be specified that with w 0 the method identifies the minimum number of faulty meters, but nothing impedes to go checking the next n counters of the sequence (7) (n is a positive integer).
• the data are supposed as collected in column for each single counter, defining a matrix D in which the column index corresponds to the single counter and the row index to the single time measurement.
• block C1 solving the minimization problem described with the equation (3). In the case of non-unique solution, choosing only one.
• block C2 checking the obtained value of direct connection with a statistical evaluation on the extent of non-technical losses (illegal connection) given by P dir and technical losses (Joule effect) given by A. In its assessment, performing a hypothesis test to determine whether what has been obtained as a direct drive can be considered a true signal or just noise. Also determining whether the value of technical losses is compatible with what is theoretically expected.
• block C6 choosing the minimum solution, i.e. the one that best approximates the balance equation, between those obtained in the previous blocks C1 and C5.
• block D analyzing the individual solutions and describing them with statistical and quartiles moments, i.e. calculating the parameters (Hi) m as described in the equations (4) and (5).
• block E ordering with the weight function (6), or building a new sequence c u for the counters, so that they are ranked by decreasing probability to deviate from the ideal value of k cu , as described in (7).
• block F calculate the maximum w 0 Equation (8), which indicates the minimum number of the first counter of the new sequence to be indicated as suspects.
• block G transforming the values of P dir obtained in the L units into a dichotomous sequence of presence/absence of illegal connection and evaluating, by a hypothesis test, the probability of illegal connection, as previously defined.
• k' in this case corresponds to the median of the values of k found in every elementary unit for the single counter
• Figure 1 block G.
• the non-negligible values of direct connection (illegal connection) visible in the table in point 7, in five of the eight sub- matrices, are also indicative of a probable connection without counter. From these values, one obtains a dichotomous sequence 0 (absence), 1 (presence) of illegal connection:
• an input power meter (40 line meter), downstream of the line transformer 45, is inserted.
• the data of the individual consumption Pi, detected by the N counters 20 relevant to the consumptions 10, and of PIN (total introduced on the line), detected by the line meter 40, are collected in 60 and optionally stored in a centralized database 70.
• the collected data can be aggregated to defined time intervals and processed using the method described. If the database 70 is present, the data can be extracted in 80 and in any case they are processed by a central processor 90 to provide the result 95.
• the method and system 100 of the invention provide, in 95, indications about the presence of illegal connection and the possible tampering or malfunction of individual counters, or it ranks the entire line as balanced (absence of illegal connection and tampered or malfunctioning meters) .
• the method of the invention it can be determined, with a minimum cost of the measurement data collection, where there are consumption anomalies in the electrical grid.
• the distinguishable anomalies are on one hand the likely presence of illegal connection to the grid, and, on the other hand, the likely presence of a malfunction or a tampering of the single counter.
• the grid operator may intervene in order to verify the prediction of the method without having to make a huge campaign of checks and to solve the anomalies with different methods depending on the case.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Complex Calculations (AREA)
• Management, Administration, Business Operations System, And Electronic Commerce (AREA)

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• 2016
  • 2016-06-03 CA CA2988372A patent/CA2988372A1/en not_active Abandoned
  • 2016-06-03 WO PCT/IT2016/000143 patent/WO2016194012A1/en active Application Filing
  • 2016-06-03 EP EP16745194.7A patent/EP3304100A1/de not_active Withdrawn

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