KR20120056796A - Process and device to determine a structure of an electric distribution network - Google Patents

Abstract

PURPOSE: A process and a device for determining the structure of an electricity distribution network are provided to determine the structure of an electricity distribution system which includes a substation supplying electricity to a set of consumers through one or more feeders. CONSTITUTION: A determination device comprises an information receiving mean, a processing means, and a communications interface means. The information receiving mean receives consumption information transmitted by a smart meter and a measuring system. An electrical power system(21) comprises a first feeder(24a) having a line, and a substation(22) having a second feeder(24b). The first feeder comprises two consumers(C1, C2). The second feeder comprises one consumer(C3).

Description

PROCESS AND DEVICE TO DETERMINE A STRUCTURE OF AN ELECTRIC DISTRIBUTION NETWORK}

The present invention relates to the field of electrical distribution on power systems, in particular on a public grid. The present invention relates to a method of determining the structure of an electrical distribution system. The invention also relates to a device for determining the implementation of such a method. The invention also relates to a data recording medium and a computer program suitable for the implementation of this method.

As shown in FIG. 1, on the power system 1, the terminal distribution of electricity is transferred from low voltage consumers 5 from a medium voltage / low voltage (MV / LV) distribution substation 2 in a particular residential home. ) Is performed at low voltage LV. The MV / LV substation 2 provides several feeders 3. Each feeder is arranged in a radial structure 4 which provides several single-phase or three-phase connections 6. This power system structure provides a single or three phase power to a certain number of consumers 5. An LV panel that distributes power to the different feeders 3 described above is located in the MV / LV substation 2. Typically there are one to eight feeders that can be protected by fuses or circuit breakers.

Low-voltage power systems are dense, sometimes overhead, sometimes underground, mixed variable equipment and cables with variable lifetimes. They are run by electric companies, some of which have a century of history where these power systems have undergone modifications, expansions and repairs. These power systems are technically simple, rarely destroyed and for this reason are not recorded very often, or at least very few and poorly.

Two factors combine themselves with this situation. First, deregulation in the electricity sector forces separation of stakeholders. Second, electricity distribution systems remain monopolistic but belong to electricity distributors bound by state regulators. The latter impose their quality of service objectives on their distributors, which should be measured in terms of the time and number of supply cutoffs experienced by each connected consumer, among others. These goals are mandatory and can lead to penalties if they are not observed. Thus, electric distributors from now on need to have very large accuracy with respect to supply cutoff data and need to have accurate information in order to better locate possible failure or bad operation.

In addition, still within the scope of deregulation, some countries have decided to install smart meters that eliminate the need for employees to take a tour to read the meters. Depending on the regulatory situation and also the electrical distributors, different architectures have been chosen to perform remote meter reading operations. In some of these architectures, some electrical distributors decided to install a data concentrator in each MV / LV distribution substation. This collector performs collection of data from each meter assigned to it. Metering data is received via line carrier current or wireless electrical means at regular frequencies (about half an hour to one day). The collector then transmits these measurements to higher levels through other communication means. Therefore, metering data from each meter is available in almost real time at each MV / LV distribution substation.

Prior to the installation of smart meters, it was economically impossible to access the metering values of each meter in near real time. Also, conventional sensor technologies do not allow current to be measured economically on each phase of each LV feeder of the MV / LV distribution substation.

As discussed above, the structure of power systems is sometimes poorly recorded. However, it is important to know these structures. Therefore, it is of great interest to be able to determine these structures in a simple, economical and efficient manner. This knowledge of the power system makes it possible to precisely identify and determine the location of non-technical current losses or poor operation, especially on the power system. In addition, the knowledge of the power system allows the imbalances of the power system to be diagnosed at the level of each feeder.

A method of using multiple measuring devices at different locations of a power system to determine the architecture of the power system is known from document US 2010/0007219. This method is very expensive because it requires multiple measurement devices at different levels of the power system. It is also possible to determine whether power has been stolen from the power system.

A method for optimizing the interpretation of data provided by a power system measurement or monitoring system is known from document US 2007/14313.

It is an object of the present invention to provide a method for determining the structure of a power system that allows the problems evoked in the above to be solved and improves on the known methods of the prior art. In particular, the present invention provides a method for determining a simple, economical and efficient structure.

According to the present invention, a method of determining the structure of an electrical distribution system comprising a substation for supplying electricity to a set of consumers via one or more feeders providing one or more phases comprises the following steps: Includes:

Receiving first electrical consumption information for each consumer of the set of consumers;

Receiving second electricity consumption information for the feeders or phases of each feeder of the substation;

Using the first electricity consumption information and the second electricity consumption information, comprising a computing phase for determining consumer subsets within the set of consumer goods, wherein the computing phase comprises: Consumers use the first electricity consumption information and the second electricity consumption information, supplied by the same predetermined feeder and / or by the same predetermined phase of the given feeder.

Advantageously, the computing phase is based on assumptions of energy conservation applied to the first electricity consumption information and the second electricity consumption information.

Advantageously, said computing phase comprises computing a coefficient that translates whether a consumer is connected to a feeder or phase.

Advantageously, a factor equal to 1 or substantially equal to 1 translates the fact that the consumer is connected to the feeder or the phase, and / or a factor equal to 0 or substantially equal to 0 indicates that the consumer consumes the feeder Or translate the fact that it is not connected to the phase.

Advantageously, the computing phase, in particular the computing phase of the coefficient, uses a least squares type optimization method.

Advantageously, said computing phase comprises the calculation of a confidence coefficient.

Advantageously, using said first electricity consumption information and second electricity consumption information comprises a comparison phase of the results of different iterations of said computing phase.

Preferably, if the different results of the iterations of the computing phase are substantially different, it is concluded that there is a malfunction or non-technical current loss on the power system.

According to the invention, a computer-readable data recording medium having a computer program recorded therein comprises software means for implementing the steps of the method defined above.

According to the invention, a device for determining the structure of an electrical distribution system comprising a substation for supplying electricity to a set of consumers via one or more feeders providing one or more phases comprises the steps of the method defined above. Hardware means for implementing and / or software.

Advantageously, said hardware means receives in particular first electrical consumption information for each consumer of said set of consumers and second electrical consumption information for said feeders or phases of each feeder of said substation. Means for receiving power consumption information relating to, analysis or processing means including means for computing, and information, in particular of consumers supplied by the same predetermined feeder and / or by the same predetermined phase of a given feeder. Means for computing and retrieving information about the subset.

According to the invention, a computer program comprises computer program encoding means adapted to carry out the steps of the method defined above when executed on a computer.

The accompanying drawings show, for illustrative purposes, embodiments of a power system comprising a device for implementing a determination method according to the invention and an execution mode of the determination method according to the invention.
1 shows a schematic diagram of a general architecture of an LV electrical distribution system.
2 shows a detailed view of an example of an LV electrical distribution system.
3 shows an example diagram of a simplified electrical distribution system.
4 is a flowchart of an execution mode of a determination method according to the present invention.

The recent installation of smart electricity consumption meters at the level of the final consumer suggests the implementation of processing and communication means in the MV / LV distribution subsystem 1. This offers the opportunity to install advanced processing functions in the MV / LV distribution substations 1 which were not previously possible. The method according to the invention determines or reconstructs, in an economical and automatic manner, the structure for the layout of the LV distribution system, in particular from the data and measurements available at the MV / LV distribution substation (i.e. any consumer 5). Determines which feeder or connection 3 is connected or even to which phase).

This enables the following:

Quantifying and locating non-technical current losses (especially power theft and commercial database errors),

Precisely know the state of current loss in the LV system and also locate the feeder that contributes the most to this current loss,

Identifying consumption imbalances per phase on the scale of each feeder, and / or

Accurately identify the number of customers affected by failures on a given LV feeder 3 and calculate a precise system average interruption duration index (SAIDI) performance index and a system average interruption frequency index (SAIFI) performance index each year and for each customer. To do.

Each consumer or end user 5 is equipped with a smart meter that allows consumption information to be sent regularly to the substation 2 connected thereto. The database located within the substation contains an account of the continuous consumption of each connected meter.

Thus, the indices representing the consumption of each consumer (effective and / or reactive and / or apparent energy, instantaneous and / or reactive and / or apparent power, instantaneous valid and / or reactive and / or apparent current, etc.) Can be specified

The consumption measurement or metering system is installed in the substation 2 at the level of each feeder 3 or at the level of each phase of each feeder 3 so that the information measured by each meter, i.e. Indexes indicative of (effective and / or reactive and / or apparent energy, instantaneous valid and / or reactive and / or apparent power, instantaneous valid and / or reactive and / or apparent current, etc.) can be measured.

In a preferred embodiment, the consumption data collected at the level of each consumer and the consumption data collected at the level of the feeder or the level of the phase in the substation 2 are synchronized, i.e. they are for the same period in the case of energy. For the same moment when power or current intensity is involved.

Whatever type of consumer (three phase or single phase), the latter is assigned to the feeder to which it is connected by the method according to the invention. Assignment to the corresponding phase is possible depending on the type of information available.

If the meters of three phase consumers provide three indices representing consumptions corresponding to each phase, then it is possible to assign each consumer to its own connected phase or phases.

If the meters of three phase consumers provide only one global index representing the total consumption of the consumer, then the allocation of each consumer to the phase or phases to which it is connected may not be possible. Nevertheless, this assignment may be made possible by another apparatus that allows the phases connected to the meters present at the level of the consumers to be identified.

As shown in FIG. 2, on the power system 1, the terminal distribution of electricity is generated from low voltage consumers 5 from a medium voltage / low voltage (MV / LV) distribution substation 2 in a particular residential home. Is performed at low voltage LV. The MV / LV distribution substation 2 is a power system structure feeder that provides several three phase lines 4, each of which is connected to the substation by means of a connection or feeder 3. This power system architecture provides single phase power or three phase power (about 100) for a given number of consumers. An LV panel that distributes power to different feeders 3 is located in the MV / LV distribution substation. There are typically one to eight feeders that may be protected by a fuse or circuit breakers. In FIG. 2, each feeder comprises four conductors: three phases of conductors, each identified by numerals 1,2,3 and a neutral conductor, identified by the letter N. In FIG. Three phase consumers are connected to each of the conductors and single phase consumers are connected to one of the phases and to the neutral. In the example of FIG. 2, the substation 2 comprises four low voltage feeders 3. Each feeder supplies a predetermined number of single phase and / or three phase consumers. Each consumer is assigned a smart meter 7 identified by a suitable reference (four digits given as an example in FIG. 2) for the distributor. Each meter transmits consumption information items (eg, effective energy information) in the single phase, and three consumption information items (eg, effective energy information) for each phase in the three phases. This information is transmitted to the device 8 for determining the power supply structure located in the substation 2, for example by means of suitable communication means (eg by radio waves or line carrier currents). In addition, the measurement system 9 measures consumption information (for example, effective energy information) on each feeder or on a phase of each feeder, and also transmits this information to the device 8. This measurement system may use wireless technology to simplify implementation on existing substations.

The determination device 8 comprises means 81 for receiving consumption information transmitted by the smart meter 7 and the measurement system 9, means for analyzing or processing this information 82 and possibly specific visual and / or Or means 83, such as information transmission means or communication interface for conveying the analysis report in audio. In particular, these means 83 enable the person in charge of the management of the power system to receive information about the structure of the power system which is estimated by implementing the determination method according to the invention.

Determination device 8 comprises hardware and / or software means which allow its operation to be controlled according to the method of forming the subject matter of the present invention. The software means comprise computer program encoding means, in particular suitable for carrying out the steps of the method according to the invention when the program is executed on a computer. The software may be included in the analysis or processing means 82.

Starting from the data described above, the determination method according to the invention finds a suitable allocation combination by assigning each meter to one of the feeders or to one of the phases of one of the feeders. In other words, the present determining method determines subsets from the entire set of consumers, each subset corresponding to all consumers connected to the same feeders or to all consumers connected to the same phase of the same feeder. do. The result can be provided in the form of a data table, as shown below for the example of the power system of FIG. 2, listed with feeders, phases and connected meters.

The following describes a method of executing the determination method according to the present invention with reference to FIG. 4, where the determination method is applied to an example of the power system 21 shown in FIG. This power system 21 includes a substation 22 with two feeders with lines 24a and 24b. The first feeder 24a includes two consumers C ₁ and C ₂ on its line 24a and the second feeder includes one consumer C ₃ on its line 24b. do.

From now on, in describing the execution mode, we will infer about the effective energy. Similar inferences for other homogeneous measurements are also possible and follow the same manner (especially reactive energy, apparent energy, active power, reactive power, apparent power, currents).

For simplicity of explanation, it is assumed that all consumers are in three phases. Thus, it is inferred by the feeder to look at the total effective energy consumed (in three phases) measured on the feeder on the one hand and the active energy measured on the other hand at the level of the consumers. This reasoning is similar to single phase consumers, except that reasoning should be inferred in phase instead of inferred by feeder.

In a first step 10, the principle of the main data and the determination method of the power system is defined. In particular, the data in the following table are defined.

For example, the energy provided at the feeder's (or feeder's phase) level is equal to the sum of the energy consumed by the consumers connected to this feeder (or to the feeder's phase), ignoring losses. Do. Thus, in the second step 20, the list of coefficients a _ij is defined as i ∈ [1; n] corresponding to the number of meters and j ∈ [a; m] corresponding to the number of feeders (Fig. 3). In the example, i ∈ [1,2,3] and j ∈ [a, b]), thereby allowing this hypothesis to be modeled. These coefficients allow interpretation of which feeder (or which phase) a given consumer is connected to. When consumer i is connected to feeder j a _ij = 1 and if consumer i is not connected to feeder j a _ij = 0.

In the case of the power system of Fig. 3, the following coefficient list (a _1a , a _1b , a _2a , a _2b , a _3a , a _3b ) is defined. In this example, the implementation of the present decision method is based on the following solution (a _1a = 1, a _1b = 0, a _2a = 1, a _2b = 0, a _3a = 0, a _3b = 1)

Specifies the following:

E _Dj (t → t + Δt) = time interval [t; energy consumed on the entire feeder j over t + Δt],

E _Ci (t → t + Δt) = time interval [t; energy consumed by the consumer i over t + Δt],

Losses _Dj (t → t + Δt) = time period [t; energy lost on feeder j over t + Δt].

Therefore, energy conservation is translated into the following formula for the different feeders j.

 In the example of FIG. 3, therefore, energy conservation is translated into the following formula for feeders a and b:

In a third step 30, a series of measurements are performed at the level of the meter of each consumer and at the level of the feeder or phase in the substation 22 for a defined period or at a defined time.

In the case of the example of FIG. 3, assume that energy measurements are made from 7h to 7h30 at the level of each consumer and at the incoming of each feeder. The results are shown in the table below.

One example of a digital application allows the proposed equation to be proven.

By multiplying the coefficient (0 or 1) corresponding to the energy of the consumers, we obtain:

The modeling is evidenced by the loss of feeder a equal to 2Wh and the loss of feeder b equal to 3Wh.

In a fourth step 40, a test is made to see if there are enough measurements to solve the above-described equations. If this is not the case, the process returns to step 30. If this is the case, proceed to step 50.

In this step, the value of the coefficient a _ij must be obtained so that it can actually write energy conservation formulas.

In the example of FIG. 3, if a single measurement is made at the level of each feeder and at the level of the consumer, and the losses are ignored, we have the following two equations for six unknowns:

here,

The values of a _1a and a _1b cannot be determined because they do not know the values of the coefficients (a _2a , a _2b ) and (a _3a , a _3b ). Thus, for example, two different sets of energy measurements are needed at the level of each meter and at the level of each feeder for a time interval from 7h30 to 8h and a time interval from 8h to 8h30.

Examples of sets of measurements are given in the table below.

If the number of measurements is sufficient, the value T of the coefficients a _1a , a _1b , a _2a , a _2b , a _3a , a _3b is obtained, for example, by a calculation to be explained further.

With a single set of measurements, generalizing to the case of n meters and m feeders, we have m equations with n × m unknowns. Thus, in order to be able to solve the equations, we need n sets of measurements.

In a fifth step 50, the above equations are solved and the coefficient a _ij Is determined.

If the loss in the power system is low (less than 4%), as discussed above, the sum of the effective energies of the consumers of a given feeder is substantially equal to the sum of the energy consumed by that feeder. Advantageously, one of the applied methods is, for example, the least square of the difference between the sum of the consumed energy measured at the level of a given feeder and the consumed energy measured at the level of all meters of consumers connected to the substation. Is minimized, wherein the consumed energies measured at the levels of all the meters of the consumers are weighted by previously defined coefficients.

Thus, the coefficient a _ij must be found so that the sum S is minimum, and S is equal to:

This means that in the case of the example of the power system of FIG. 3, the coefficients a _1a , a _1b , a _2a , a _2b , a _3a , a _3b must be obtained such that the sum S is minimum,

와 같으며,Where S is

Is the same as

to be.

Convergence of the algorithm is ensured by several means. In order to facilitate its convergence, several constraints are added, for example:

≧ the value of the coefficients is theoretically 0 or 1, but if a resolution technique is used in real, the method computes the actual values in order to find a solution, especially in spite of measurement errors and energy losses. Therefore, there is a need to define a solution to be obtained. This is translated by the following system:

[epsilon]% represents a value that allows for possible measurement and computing errors to be considered, depending on the equipment used and the losses used. 15% is about the size available.

→ When consumers i, C _i are connected to feeders j, D _j , the consumers cannot be connected to other feeders. This constraint is translated by the following system:

The confidence index is defined as follows:

→ Upon completion of the previous calculation, a coefficient a _ij with a value contained between −ε% and (1 + ε%) was obtained.

For the example addressed, the following was obtained:

(a _1a , a _1b , a _2a , a _2b , a _3a , a _3b ) = (0.625, 0.375, 1, 0, 0.075, 0.925). It can be seen that the values of the coefficients a _1a , a _1b are not as close to 1 or 0 as the other coefficients. Therefore, the results are not reliable, so it is necessary to check these results by reapplying the algorithm to another data set. This reliability can be checked by reproducing steps 30 to 50 several times at different times, in particular for different sets of data measured at different times of the day or during other days or other months.

In this step 50, confidence indices are calculated.

To make a _ij an integer, rounding to the nearest integer is performed.

A _ij very close to 0 (Eg 0.05) can be clearly identified as zero. Similarly, a _ij very close to 1 (Eg 1.12) may be identified as one.

The closer a _ij is to 0.5, the more obscure the assignment. Therefore, it is necessary to define a reliability index that translates the distance of the coefficient a _ij with respect to 0.5.

Possible definitions of the reliability index are:

, % 단위

, % unit

In a sixth step 60, these confidence indices are tested. Acquiring a poor reliability index (less than Ref1) translates to measurement error, dependence of equations held, or the presence of additional consumption on the power system (theft, abnormal loss, etc.). If the least good reliability indices are higher than the predefined value Ref1, the results of the different coefficients a _ij that determine the structure of the power system, ie the connections between the feeders and the consumers, are recorded in step 70. If the least good confidence indices are not higher than the predefined value Ref1, the process proceeds to step 80, in which the obtained coefficient a _ij Are stored, and the previous steps 10 to 80 are repeated until the number of repetitions is equal to the predefined value Ref2.

This is tested in step 90. If the number of repetitions is equal to the value Ref2, the process proceeds to step 100, in which step 100 is tested whether the different coefficients obtained and installed in successive steps 80 are the same or similar. If this is the case, the process returns to step 60. If this is not the case, proceed to step 110 where it is concluded that there is a measurement error or non-technical current loss on the power system.

By executing this algorithm several times (the number of iterations is fixed by the user), the power system configurations obtained on the output can be compared. If they are all the same, it can be appreciated that the solution obtained corresponds to reality. If this is not the case, the diagnosis is not clear. Then, there is a high possibility that there is a non-technical current loss. As long as the number of repetitions is less than the predefined value Ref2, steps 10 to 80 are repeated.

By taking again the example of the power system of FIG. 3, the following was obtained as the value of the coefficients: (a _1a , a _1b , a _2a , a _2b , a _3a , a _3b ) = (0.625, 0.375, 1, 0 , 0.075, 0.925). Then, coefficient a ₁₁ And a ₁₂ were unreliable.

The data set in the table below is now considered and the calculation step 50 is restarted.

The following was obtained: (a _1a , a _1b , a _2a , a _2b , a _3a , a _3b ) = (1, 0.9932, 0, 0, 0.0068, 1). The results are very reliable. By taking different sets of measurements, the reliability of the results can be increased.

The value Ref1 is equal to 80%, for example.

The value Ref2 is the number of iterations made before considering that the system cannot converge due to external problems. The number of iterations Ref2 increases the probability of convergence while increasing the resolution time and the required history capacity.

In other embodiments, where the consumers are also electricity producers, the allocation of each consumer to the phase or phases to which it is connected is possible only if the production information is known, ie the meter only transmits information about consumption. In addition, information about production must be transmitted. You need to actually know which information is about production and which information is about consumption.

Although the above description refers to MV / LV substations, the present invention is also applicable to substations or devices having only a low voltage (LV).

Claims (12)

A substation 2 for supplying electricity to the set of consumers 5, C _i via one or more feeders 3, D _j providing one or more phases. As a method of determining the structure of the electrical distribution system 1,
Receiving first electricity consumption information for each consumer of the set of consumers;
Receiving second electricity consumption information for the feeders or phases of each feeder of the substation;
Using the first electricity consumption information and the second electricity consumption information, comprising a computing phase for determining consumer subsets within the set of consumers, the same subset Consuming products comprising the first electricity consumption information and the second electricity consumption information, supplied by the same predetermined feeder and / or by the same predetermined phase of the given feeder. How to determine the structure of a distribution system. The method of claim 1,
And said computing phase is based on an assumption of energy conservation applied to said first electricity consumption information and said second electricity consumption information. The method according to claim 1 or 2,
Structure of an electrical distribution system characterized in that the computing phase comprises computing the consumption material (C _i) the feeder (D _j), or the transfection of slate (translate) coefficient for whether connected to the phase (a _ij) How to determine. The method of claim 3, wherein
A coefficient a _ij equal to 1 or substantially equal to 1 translates the fact that the consumer C _{i is} connected to the feeder or phase D _j , and / or
The structure of the electrical distribution system, characterized in that the coefficient a _ij equal to zero or substantially equal to zero translates the fact that the consumer C _i is not connected to the feeder or the phase D _j . How to determine. The method according to any one of claims 1 to 4,
Said computing phase, in particular the computing phase of coefficient (a _ij ), uses a least squares type optimization method. 6. The method according to any one of claims 1 to 5,
Wherein said computing phase comprises computing a confidence coefficient. The method according to claim 6,
Using the first electricity consumption information and the second electricity consumption information comprises a comparison phase of the results of different iterations of the computing phase. The method of claim 7, wherein
If the different results of the iterations of the computing phase are substantially different, it is concluded that there is a malfunction or non-technical current loss on the power system. . A computer-readable data recording medium having a computer program recorded thereon,
A data recording medium comprising software means for implementing the steps of the method according to any one of claims 1 to 8. S via one or more feeders (feeder) (3, D _j) of providing at least one phase consumption body electrical distribution system (1) comprising a sub-station (2) for supplying electricity to a set of (5, C _i) As the device (8) for determining the structure of
10. A device for determining the structure of an electrical distribution system comprising hardware means (81, 82, 83) and / or software for implementing the steps of the method of any of claims 1-9. 11. The method of claim 10,
The hardware means,
Means for receiving power consumption information, in particular for receiving first electrical consumption information for each consumer of said set of consumers and second electrical consumption information for said feeders or phases of each feeder of said substation; (81),
Analysis or processing means 82, including means for computing, and
Means for computing and retrieving information, in particular information about a subset of consumers supplied by the same predetermined feeder and / or by the same predetermined phase of the given feeder. A device for determining the structure of an electrical distribution system. As a computer program,
A computer program comprising computer program encoding means adapted to carry out the steps of the method of any one of claims 1 to 9 when the computer program is executed on a computer.

Images