WO2012101610A1

WO2012101610A1 - Disaggregation apparatus

Info

Publication number: WO2012101610A1
Application number: PCT/IB2012/050401
Authority: WO
Inventors: Ying Wang; Alessio Filippi; Ronald Rietman
Original assignee: Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 2011-01-28
Filing date: 2012-01-28
Publication date: 2012-08-02
Anticipated expiration: 2013-07-28

Abstract

The invention relates to a disaggregation apparatus for determining electrical statuses of electrical consumers (2, 3, 4) in an electrical network (4). An overall electrical parameter like the overall current of the electrical network (13) is measured, filtered and sampled. Electrical signatures of the electrical consumers are provided, wherein the electrical signatures are assigned to the statuses of the electrical consumers, filtered and sampled. The filter for filtering the overall electrical parameter and the electrical signatures is adapted for at least one of reducing correlations between the electrical signatures and enhancing the dynamic range for the sampling. The statuses of the electrical consumers are determined depending on the overall electrical parameter and the electrical signatures. The filtering leads to a determination of the statuses of the electrical consumers having a high reliability and a high accuracy.

Description

Disaggregation Apparatus

FIELD OF THE INVENTION

The invention relates to a disaggregation apparatus, a disaggregation method and a disaggregation computer program for determining electrical statuses of electrical consumers in an electrical network. BACKGROUND OF THE INVENTION

The article "Nonintrusive Appliance Load Monitoring Based on Integer Programming" by Kosuke Suzuki, et al, SICE Annual Conference 2008, August 20 to 22, 2008, The University Electro-Communications, Japan discloses an apparatus for nonintrusive appliance load monitoring in an electrical network. The apparatus measures the consumed overall electrical current of the electrical network and compares the measured consumed overall electrical current with electrical current signatures of electrical consumers of the electrical network, in order to determine which electrical consumer is switched on and which electrical consumer is switched off. However, this disaggregation provides only a reduced accuracy in determining the respective switch on/off status.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a disaggregation apparatus, a disaggregation method and a disaggregation computer program for determining electrical statuses of electrical consumers in an electrical network, wherein the disaggregation can be performed with an improved accuracy.

In a first aspect of the present invention a disaggregation apparatus for determining electrical statuses of electrical consumers in an electrical network is presented, wherein the disaggregation apparatus comprises:

- an electrical parameter measuring unit for measuring an overall electrical parameter of the electrical network,

- a filtering unit for applying a filter to the measured overall electrical parameter, - a sampling unit for sampling the filtered measured overall electrical parameter,

- an electrical signature providing unit for providing electrical signatures of the electrical consumers, wherein the electrical signatures are assigned to the statuses of the electrical consumers, filtered by applying the filter to the electrical signatures and sampled by the sampling unit,

- a status determination unit for determining the statuses of the electrical consumers depending on the overall electrical parameter and the electrical signatures,

wherein the filter is adapted for at least one of reducing correlations between the electrical signatures and enhancing the dynamic range for the sampling by the sampling unit.

Since the filter is adapted for at least one of reducing correlations between the electrical signatures and enhancing the dynamic range for the sampling by the sampling unit, the filtering leads to a determination of the statuses of the electrical consumers having a high reliability and a high accuracy, in particular, if the filter reduces correlations, even if the shape of the electrical signatures is similar.

The status of an electrical consumer is, for example, a switched-on status or a switched-off status of the electrical consumer. An electrical consumer can also comprise more than two statuses, for example, it can comprise a switched-on status, a standby status and a switched-off status. Moreover, an electrical consumer can comprise several statuses which relate to different operation modes of the electrical consumer. For instance, an electrical consumer can be a washing machine, which comprises different statuses depending on different operational modes of the washing machine.

The electrical parameter measuring unit is preferentially adapted to measure the overall electrical parameter of the electrical network at a single point such that it is not necessary to measure an electrical parameter at each electrical consumer for determining the statuses of the electrical consumers. The overall electrical parameter of the electrical network can be measured at a single point and this overall electrical parameter can be used for determining the statuses of the electrical consumers of the electrical network.

The overall electrical parameter is preferentially periodic and the overall electrical parameter measured at a certain time corresponds preferentially to a period of the overall electrical parameter measured at that certain time, wherein the period of the overall electrical parameter is sampled by a number of sampled electrical parameter values preferentially such that the Nyquist criterion is fulfilled. Correspondingly, also the electrical signature corresponds preferentially to a period, which is sampled by a number of electrical parameter values such that the Nyquist criterion is fulfilled.

It is preferred that the status determination unit is adapted to determine the statuses by iteratively solving an equation describing the measured overall electrical parameter as a combination of the electrical signatures of the electrical consumers. It is further preferred that for iteratively solving the equation an -norm minimization method is applied. It is also preferred that the li-norm minimization method is a greedy pursuit algorithm. In a preferred embodiment the greedy pursuit algorithm is one of an appliance matching pursuit algorithm and an appliance orthogonal matching pursuit algorithm. The use of these algorithms further improves the accuracy of determining the statuses of the electrical consumers in the electrical network.

Based on known electrical signatures, the filter can be configured such that correlations between the electrical signatures are reduced and/or the dynamic range for the sampling is enhanced. A lot of different filters, which reduce correlations between electrical signatures and/or enhance the dynamic range for the sampling by the sampling unit, are possible. In an embodiment, the filter is a notch filter. Preferentially, the filter is adapted to remove a utility frequency of the electrical network. In particular, the filter is adapted to remove + 50 Hz components from the electrical signatures and the overall electrical parameter. By using such a filter correlations between the electrical signatures can be reduced very effectively, thereby further improving the accuracy of determining the statuses of the electrical consumers.

In a preferred embodiment the electrical parameter measuring unit is adapted to measure the overall electrical current of the electrical network as the overall electrical parameter.

The sampling unit is preferentially an analog-to-digital converter.

In a further aspect of the present invention a disaggregation method for determining electrical statuses of electrical consumers in an electrical network is presented, wherein the disaggregation method comprises:

- measuring an overall electrical parameter of the electrical network by an electrical parameter measuring unit,

- applying a filter to the measured overall electrical parameter by a filtering unit,

- sampling the filtered measured overall electrical parameter by a sampling unit, - providing electrical signatures of the electrical consumers by an electrical signature providing unit, wherein the electrical signatures are assigned to the statuses of the electrical consumers, filtered by applying the filter to the electrical signatures and sampled by the sampling unit,

- determining the statuses of the electrical consumers depending on the overall electrical parameter and the electrical signatures,

In a further aspect of the present invention a disaggregation computer program for determining electrical statuses of electrical consumers in an electrical network is presented, wherein the computer program comprises program code means for causing a disaggregation apparatus as defined in claim 1 to carry out the steps of the disaggregation method as defined in claim 10, when the computer program is run on a computer controlling the disaggregation apparatus.

It shall be understood that the disaggregation apparatus of claim 1, the disaggregation method of claim 10, and the disaggregation computer program of claim 11 have similar and/or identical preferred embodiments, in particular, as defined in the dependent claims.

It shall be understood that a preferred embodiment of the invention can also be any combination of the dependent claims with the respective independent claim.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following drawings:

Fig. 1 shows schematically and exemplarily an embodiment of an electrical network comprising a disaggregation apparatus for determining electrical statuses of electrical consumers in the electrical network,

Fig. 2 shows an example of a period of a steady-state current drawn by an electrical consumer in the time domain, Fig. 3 shows exemplarily the period of the steady-state current drawn by the electrical consumer in the frequency domain,

Figs. 4 to 17 show exemplarily current shapes of electrical signatures of electrical consumers,

Fig. 18 shows exemplarily the rms current strengths of the electrical signatures,

Figs. 19 to 32 show exemplarily the current shape of filtered electrical signatures of the electrical consumers,

Fig. 33 shows exemplarily the rms current strengths of the filtered electrical signatures of the electrical consumers,

Fig. 34 shows schematically and exemplarily an illustration of correlations of current shapes of the electrical signatures,

Fig. 35 shows schematically and exemplarily an illustration of a correlations of the current shapes of filtered electrical signatures of the electrical consumers, and

Fig. 36 shows a flowchart exemplarily illustrating an embodiment of a disaggregation method for determining electrical statuses of electrical consumers in an electrical network. DETAILED DESCRIPTION OF EMBODIMENTS

Fig. 1 shows schematically and exemplarily an embodiment of a disaggregation apparatus 1 for determining electrical statuses of electrical consumers 2, 3, 4 in an electrical network 13. In particular, in Fig. 1 the electrical network 13 is represented by an electrical circuit model of a household, where multiple electrical consumers 2, 3, 4 are connected as parallel loads that can be switched on and switched off independently.

The disaggregation apparatus 1 comprises an electrical parameter measuring unit 5 for measuring an overall electrical parameter of the electrical network 13. In this embodiment, the electrical parameter measuring unit 5 is a current meter for measuring the overall electrical current of the electrical network 13 as the overall electrical parameter. The current meter 5 and a voltage meter 11 are placed at a central monitoring point, for example, at a main electric panel of a home. The voltage meter 11 measures the source voltage delivered by a power source 12, for example, a power utility. In this embodiment, the source voltage comprises a sinusoidal wave of 50 Hz. When an electrical consumer is turned on and is in the d -th ( d = 1,2,..., N_d ) operation mode, it draws a current signal denoted as i_d during steady-state. For example, if three electrical consumers are present, wherein each electrical consumer has only a single operation mode, there are three operation modes being the switched-on modes of the three electrical consumers. If, in this example, the second electrical consumer is turned on, it is in the second operation mode. The steady-state current waveform has several properties: 1) repeatable with, in this embodiment, a fundamental period of 1/50 s, 2) unique so that it can be used as an electrical signature of the operation mode of the respective electrical consumer, and 3) additive if multiple electrical consumers are switched on. The current meter 5 measures the overall electrical current i_^ , i.e. the current signal drawn by the total load, which is the sum of the current signals i_d of the electrical consumers 2, 3, 4 which are switched on.

The disaggregation apparatus 1 further comprises an electrical signature providing unit 7 for providing electrical signatures of the electrical consumers 2, 3, 4, wherein the electrical signatures are assigned to statuses of the electrical consumers and are filtered by applying a filter being adapted to reduce correlations between the electrical signatures. The electrical signatures can be determined by measuring the steady- state current waveforms of each electrical consumer. The steady- state current waveforms of an electrical consumer can be measured by the current meter 5, while only the respective electrical consumer is switched on. It is also possible that the steady-state current waveforms are measured individually off-line, for example, by using the current meter 5 or another current meter, which is connected to the respective electrical consumer such that only the current of the respective electrical consumer is measured. The steady-state current waveforms form a signature data base for an on-line determination of statuses of the electrical consumers, in particular, for an on-line identification of the electrical consumers which are switched on.

Fig. 2 shows schematically and exemplarily a steady-state current in ampere drawn by a light emitting diode (LED) light bulb being an electrical consumer depending on the time t in seconds s . Fig. 2 corresponds to one period of the steady- state current in the time domain. Fig. 3 shows schematically and exemplarily the corresponding frequency domain spectrum, i.e. the Fourier transform of the time domain waveform shown in Fig. 2, wherein f denotes the frequency.

The Nyquist rate of the current signal, which is defined as the bandwidth of the spectral components satisfying a threshold, e.g., < 20 dB below the peak spectrum, is denoted by F_s . The spectrum in Fig. 3 suggests that the Nyquist rate of the current signal is F_s = 10 kHz. One period (T = l/50s) of the current signal contains N =TF_S Nyquist rate samples.

The current signal of the d -th operation mode is expressed by an N x 1 vector (for one period), l = \i_d (1) where i_d is normalized s.t. i"i_d = 1 and is the amplitude. The Nyquist rate digital signal representation of (1) can conceptually be viewed as the raw analog current signal.

Although Fig. 1 shows exemplarily only three electrical consumers 2, 3, 4, the electrical network 13 can of course comprise less or more than three electrical consumers. In an embodiment, the electrical network 13 comprises different types of lamps, a vacuum cleaner, a television, a DVD-player, a hairdryer, and a kettle. This set-up is fed by the power source 12 being, in this embodiment, mains power that behaves as a service entry point delivering electricity to a house, in which, in this embodiment, the electrical network is installed. The current meter 5 measures the overall electrical current and the voltage meter 11 measures the mains voltage. The current meter 5 is, for example, an Agilent current probe placed around a single core of a life or neutral wire. The voltage meter 11 is preferentially a differential voltage probe, which in principle could be placed at any socket in the house. Usually, each electrical consumer has its own steady-state current waveform as its unique electrical signature. For some multi-mode electrical consumers like for the kettle, which may have a standby and a cooking mode or like for the vacuum cleaner, which may have a low- power and a high-power mode, each operation mode, i.e. each status of the respective electrical consumer, has a unique steady-state current waveform counted as an electrical signature. The number N_d denotes the number of electrical signatures, which, in this case, is different to the number of electrical consumers. For example, if the electrical network 13 comprises twelve electrical consumers including a kettle and a vacuum cleaner, N_d is fourteen, if the kettle and the vacuum cleaner have two electrical signatures and the other electrical consumers each have a single electrical signature.

In this embodiment, the signal from the current meter 5 is sampled by a 24-bit analog-to-digital converter (ADC) running at F_s =10 kHz, which is the above exemplarily mentioned Nyquist rate. In other embodiments, the current signal from the current meter 5 can also be sampled by another ADC running at another frequency. Since, in this

embodiment, the current signal from the current meter 5 is sampled with a sampling rate being the Nyquist rate, the digitized current signal can conceptually viewed as an analog signal, which can be further processed.

The electrical signature providing unit 7 comprises preferentially a signature data base, which is constructed by collecting the current waveform of each electrical consumer, or, if an electrical consumer comprises several operation modes, of each operation mode of the respective electrical consumer, individually beforehand, i.e. before performing the disaggregation. The respective current waveform can be measured by the current meter 5, while only the respective electrical consumer is switched on and, in particular, is operated in a known certain operation mode, and while the other electrical consumers are switched off. The electrical signature providing unit 7 can be adapted to provide a self-learning algorithm which can be designed to build the signature data base automatically when an unknown electrical consumer is plugged in. For example, in this case a user can be asked via the output unit 10, which is preferentially a display, to switch all other electrical consumers off and to switch only the new unknown electrical consumer on, wherein then the current meter 5 measures the current waveform of the new unknown electrical consumer, which is stored in the signature data base as the signature of this new unknown electrical consumer.

Figs. 4 to 18 show the electrical signatures of the raw current, i.e. without having applied the below described filtering procedure, wherein Figs. 4 to 17 describe the respective current shape denoted by i_d and wherein Fig. 18 shows the rms current strengths

I_rms = A_j / N in ampere, wherein 230 A_j / N gives the rms power in Watts. In Figs. 4 to

18 reference number 14 relates to a compact fluorescent lamp (CFL) with 20 W, reference number 15 relates to a 5 W CFL, reference number 16 relates to a halogen lamp with 50 W, reference number 17 relates to another halogen lamp with 20 W, reference number 18 relates to an incandescent light bulb, reference number 19 relates to an LED, reference number 20 relates to a hair dryer, reference number 21 relates to a vacuum cleaner in the low-power mode, reference number 22 relates to a vacuum cleaner in the high-power mode, reference number 23 relates to a television, reference number 24 relates to a kettle in the standby mode, reference number 25 relates to the kettle in a cooking mode, reference number 26 relates to a living colours lamp shining red light at high level (lcRH) and reference number 27 relates to a DVD player. can be seen in Figs. 4 to 17, different loads produce different current shapes, while certain loads with similar circuit characteristics produce very similar current shapes like the resistive loads including hairdryer, kettle in the cooking mode, halogen lamp, and incandescent lamp, which all have a sinusoidal current shape. Fig. 18 shows that, in this embodiment, the current strength ranges from 0.03 A to 9.29 A.

The disaggregation apparatus 1 further comprises a filtering unit 6 for applying a filter to the measured overall electrical parameter, i.e. to the electrical overall current measured by the current meter 5. The filter is adapted to reduce correlations between the electrical signatures. The electrical signatures i_d are filtered to improve the signal condition for later processing. The corresponding filtered version of equation (1) is

where W{-} represents the filter, in particular without changing the length of i_d , u_d is normalized s.t. u_d u_d = 1 , and B_d is the amplitude. Generally, W{-} can be any filter or transform designed to enhance the signal dynamic range for ADC sampling, and/or to reduce the signal correlations for disaggregation. In the remainder of this description, equation (2) is used as a general expression for the current signal, which includes equation

(1) as a special case, i.e., when wj i_d J= I_N i_d , u_d = i_d and B_d = . I_N is an N x N identity matrix.

A basis matrix of size N x N_d is defined as = [_Ulu₂ u_N ] (3)

Ignoring the additive noise term, the overall current signal is

wherein B = diag[B_t B₂ · · · B_Nj ] is a diagonal matrix, and s is an N_d x 1 status signal vector, with elements s_d equal to 1 or 0 indicating whether the d -th status is present or not. Preferentially, equation (4) represents conceptually the analog current signal before ADC, with the bandwidth of F_s Hz.

In an example, the filter W{-} is a notch filter removing the +50 Hz components of the raw signal, with the transfer function of

H (z) = (l - 2cosiD₀z^_1 + z^~2)/(l - 2r COS CDQ Z ¹ + r ²z^~2) , where ω₀ = 2;r50/F_s and r = 0.8 is a parameter (0 < r < 1) controlling the width of the notch. The signatures of the filtered current are exemplarity shown in Figs. 19 to 33. Without the 50 Hz components, the higher order harmonics become more dominant and the current shapes become more fluctuating as shown in Figs. 19 to 32. The filtered current strengths ranges from 0.01 A to 0.77 A as shown in Fig. 33, which decreases a lot as compared to the un-filtered current strengths shown in Fig. 18. The similarity between two current shapes (indexed by d_: and d₂ ) can be described by calculating the correlation as R. (d_t , d₂ ) = i " i_d for the raw signal, and R_u (d_t , d_s ) = u"u_d2 for the filtered signal. The results are exemplarily illustrated in Figs. 34 and 35, where the correlation is represented by gray values, the whiter the more correlated and the darker the less. The signature correlations decrease significantly after notch-filtering, which assists the disaggregation.

The status signal s is denoted as being K₀ -sparse if it contains only

K^K_Q « N_D ) non-zero entries. If it is assumed that at any steady state only a small number of electrical consumers can be simultaneously switched on, the status signal s is K₀ -sparse.

A sample unit 8 samples the signal i to a sampled signal i_m preferentially in accordance with following equation: ί„₁ = Φί = Ψ_ηιΒ8 (5) Since the signal i can conceptionally be viewed as an analog signal or, in an embodiment, is a real analog signal, the sampling unit 8 can be regarded as being an analog- to-digital converter for converting the analog signal i to the digital signal i_m . A new basis matrix T_m is given by m = O = [_mi m₂ m_N ] (6) where m_d = < u_d is the basis vector of the measured sampled signal. The matrix Φ is I_N , wherein I_N is an identity matrix with the size N x N and wherein Φ represents the conventional sampling with the ADC running at F_s Hz.

The sampling procedure defined by equation (5) can be implemented by using analog circuits, where the multiplication of Φ and i is performed using mixers and integrators as disclosed in, for example, the article "Random sampling for analog-to- information conversion of wideband signals", by J. Laska et al., IEEE Power and Energy Magazine, pp. 56-63, Mar/ Apr 2003, which is herewith incorporated by reference. The resulting overall electrical parameter i_m is used by a status determination unit 9 for determining the statuses of the electrical consumers depending on the overall electrical parameter i_m and the electrical signatures. The status determination unit can comprise a local microprocessor attached to, for example, the current meter and/or the voltage meter, or the status determination unit can comprise a remote personal computer, to which the current meter 5 may send the measured currents, wherein in the latter case the current meter 5 is equipped with a wireless or wired communication module.

The status determination unit 9 is preferentially adapted to determine the status signal s based on the overall electrical parameter i_m, given T_m and B representing the known electrical signatures of the electrical consumers. Equation (5) can be rewritten as

where z = Bs is the status signal weighted by the amplitudes. One

straightforward solution of z can be obtained via the least-square (LS) estimate,

where† denotes the Moore-Penrose pseudoinverse of a matrix. The LS minimizes the 1₂ -norm. However, preferentially the 1_: -norm minimization approach is employed, i.e., z = arg s.t. ί_ηι = Ψ_ηιζ (9)

The optimization problem of equation (9) can be solved by greedy pursuit algorithms such as orthogonal matching pursuit (OMP) as disclosed in, for example, the article "Signal recovery from random measurements via orthogonal matching pursuit" by J. Tropp and A. Gilbert, IEEE Trans, on Information Theory, pp. 4655-4666, December 2007, which is herewith incorporated by reference. The status determination unit 9 can, for example, be adapted to apply an OMP algorithm, which is adapted to the settings of the electrical consumer identification, wherein this algorithm is in the following denoted as A- OMP. However, the status determination unit 9 can also be adapted to apply another algorithm for solving equation (9) like an appliance orthogonal matching (A-MP) algorithm.

The A-MP and the A-OMP algorithms will in the following be described in more detail. The set Ω = {l,2,...,N_d } is the index set of all operation modes of the electrical consumers, wherein Ω_κ = {d d₂,...,d_K } c Q is the index set of the active operation modes selected by the algorithms. An electrical consumer can comprise one or several operation modes. If an electrical consumer has only one operation mode, then this operation mode corresponds to the single on-status of the respective electrical consumer. The A-MP algorithm has as input i_m, Ψ_ηι, B, and the thresholds α, ε . The A-MP algorithm is initialized by setting the residual r₀ to the overall electrical parameter (r₀ = i_m) and the index set Ω₀ to an empty set (Ω₀ = 0) . In the k -th iteration preferentially following steps are performed:

1. Select some candidate electrical consumers

d = ^rk^Hi^md /|l^md || >

C = {d:p_d > a max _d }, d e Q \ Q_t .

2. From the candidate set C , select the one electrical consumers that minimizes the residual power

d_k = arg rnin | r_k_₁ - B_dm_d

3. Update the residual

rk = ^rk-i - ^Bd_t ^m _dl . et = Fk-ill ^" kll /'II l ·

The iteration is preferentially performed until a stop criterion is fulfilled. In embodiment, the stop criterion is fulfilled, if e_k < ε or k = N_d . The result is the set Q_k , wherein the index k denotes the number of performed iterations. The A-OMP algorithm has as input i_m,¾^f _m, and a threshold ε . The A-OMP algorithm is initialized by setting the residual r₀ to the overall electrical parameter (r₀ = i_m) and the index set Ω₀ to an empty set (Ω₀ = 0) . Moreover, initially a matrix containing the orthogonalized selected basis vectors Γ₀ = [ ] is provided. The k -th iteration of the A-OMP algorithm comprises preferentially the following steps:

1. Select one electrical consumer and add to the index set

d = ^rk^Hi^md /||^md || >

d_k = arg max p_d Sl_k = Sl_{k l} u {d_k } .

d e l,...,N_d

2. Orthogonalize and normalize the selected basis vector, and add it to the orthogonalized basis matrix

m_dl = m_di -r_k__ir_k ⁱ_₁m_di , g_k = ^lft _dl /||m_di || ,

r_k =[r_k__lgJ.

3. Update the residual

The iteration stops, if a stop criterion is fulfilled, for example, if e_k < ε or k = N_d . The output of the A-OMP algorithm is the index set Ω_κ .

A-MP has less computational complexity than A-OMP, since A-OMP performs matrix multiplication in the orthogonalization step of each iteration and also needs more iterations to converge. A-OMP is more robust than A-MP when the electrical consumers signature waveforms are very correlated. Given Ω_κ , a mutilated basis matrix

Ψ_{ω K} = [m_d in_d2 · · · m_dK ] and a mutilated coefficient vector z_K = [z_di ^■■■ z_A^ ]^T can be obtained such that equation (7) can be rewritten as i_m = Ψ,_η κΖ χ . Then z_K is estimated by

Similarly, a mutilated status signal vector is defined as s_K = [s_diS_d2 · · · s_dK ]^T . Knowing the amplitudes, we estimate s_K and obtain a refined index set as ^§d_k = ¾_k. ^dk ^{e Ω}κ (11)

Ω_κ. = (d_k : s_dk > 0.5} (12) where a threshold is set to be 0.5 given that the status signal is either 0 or 1 with equal probability assumed.

In the following an embodiment of a disaggregation method for determining electrical statuses of electrical consumers in an electrical network will exemplarily be described with reference to a flowchart shown in Fig. 36.

In step 101, an overall electrical current of the electrical network is measured by the electrical parameter measurement unit 5. In step 102, a filter is applied to the measured overall electrical parameter by the filtering unit 6 and, in step 103, the filtered measured overall electrical parameter is sampled by the sampling unit 8. In step 104, electrical signatures of the electrical consumers are provided by the electrical signature providing unit 7, wherein the electrical signatures are assigned to the statuses of the electrical consumers, filtered by applying the filter to the electrical signatures and sampled by the sampling unit 8. The filter is adapted for at least one of reducing correlations between the electrical signatures and enhancing the dynamic range for the sampling by the sampling unit 8. In step 105, the statuses of the electrical consumers are determined depending on the overall electrical parameter and the electrical signatures.

Generally, the quality of disaggregation can be low, for example, "off electrical consumers may be wrongly identified as being "on", especially in following two cases: 1) when the number of "on" electrical consumers is small comparing to the total number of electrical consumers under monitoring, 2) when some electrical consumers have highly correlated current waveforms due to similar circuit characteristics, for example, resistive loads including halogen lamp, incandescent lamp, water cooker and hairdryer may all have a sinusoidal current waveform.

The disaggregation apparatus and disaggregation method perform an iterative algorithm using a sparse reconstruction approach to minimize the L -norm of the solution, together with the pre-filtering designed to reduce the current waveform correlations to assist disaggregation. As a result, the disaggregation apparatus and disaggregation method provide a more robust identification of the individual electrical consumers usage information, i. e. information of the current operation mode of the respective electrical consumer.

In the above described embodiments, the filter W{-} is a notch filter removing the + 50 Hz components of the raw signal. Generally, the filter can be any filter or transform designed for several purposes, i. e., enhance the signal dynamic range for ADC, in which case W{-} is an analog filter, and/or reduce the signal correlations for disaggregation, in which case W{-} could be either an analog filter or a digital filter depending on the implementation efficiency.

The two proposed disaggregation algorithms can be traded-off in terms of complexity and performance. A-MP has less computational complexity than A-OMP, since A-OMP performs matrix multiplication in the orthogonalization step of each iteration and also needs more iterations to converge. A-OMP is more robust than A-MP when the appliance signature waveforms are very correlated.

The disaggregation apparatus and disaggregation method can be used for, for example, smart energy monitoring, energy disaggregation, smart energy control, et cetera.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

A single unit or device may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The filtering, the determinations like the determination of the statuses of the electrical consumers, et cetera, performed by one or several units or devices can be performed by any other number of units or devices. For example, steps 102 to 104 can be performed by a single unit or by any other number of different units. The filtering, determinations et cetera and/or the control of the disaggregation apparatus in accordance with the disaggregation method can be implemented as program code means of a computer program and/or as dedicated hardware.

A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

Any reference signs in the claims should not be construed as limiting the scope.

The invention relates to a disaggregation apparatus for determining electrical statuses of electrical consumers in an electrical network. An overall electrical parameter like the overall current of the electrical network is measured, filtered and sampled. Electrical signatures of the electrical consumers are provided, wherein the electrical signatures are assigned to the statuses of the electrical consumers, filtered and sampled. The filter for filtering the overall electrical parameter and the electrical signatures is adapted for at least one of reducing correlations between the electrical signatures and enhancing the dynamic range for the sampling. The statuses of the electrical consumers are determined depending on the overall electrical parameter and the electrical signatures. The filtering leads to a determination of the statuses of the electrical consumers having a high reliability and a high accuracy.

Claims

CLAIMS:

1. A disaggregation apparatus for determining electrical statuses of electrical consumers (2, 3, 4) in an electrical network (4), the disaggregation apparatus (1) comprising:

- an electrical parameter measuring unit (5) for measuring an overall electrical parameter of the electrical network (13),

- a filtering unit (6) for applying a filter to the measured overall electrical parameter,

- a sampling unit (8) for sampling the filtered measured overall electrical parameter,

- an electrical signature providing unit (7) for providing electrical signatures of the electrical consumers (2, 3, 4), wherein the electrical signatures are assigned to the statuses of the electrical consumers, filtered by applying the filter to the electrical signatures and sampled by the sampling unit (8),

- a status determination unit (9) for determining the statuses of the electrical consumers (2, 3, 4) depending on the overall electrical parameter and the electrical signatures,

wherein the filter is adapted for at least one of reducing correlations between the electrical signatures and enhancing the dynamic range for the sampling by the sampling unit (8).

2. The disaggregation apparatus as defined in claim 1, wherein the status determination unit (9) is adapted to determine the statuses by iteratively solving an equation describing the overall electrical parameter as a combination of the electrical signatures of the electrical consumers.

3. The disaggregation apparatus as defined in claim 2, wherein for iteratively solving the equation an -norm minimization method is applied.

4. The disaggregation apparatus as defined in claim 3, wherein the li-norm minimization method is a greedy pursuit algorithm.

5. The disaggregation apparatus as defined in claim 4, wherein the greedy pursuit algorithm is one of an appliance matching pursuit algorithm and an appliance orthogonal matching pursuit algorithm.

6. The disaggregation apparatus as defined in claim 1, wherein the filter is a notch filter.

7. The disaggregation apparatus as defined in claim 1, wherein the filter is adapted to remove a utility frequency of the electrical network (13).

8. The disaggregation apparatus as defined in claim 1, wherein the electrical parameter measuring unit (5) is adapted to measure the overall electrical current of the electrical network (13) as the overall electrical parameter.

9. The disaggregation apparatus as defined in claim 1, wherein the sampling unit (8) is an analog-to-digital converter.

10. A disaggregation method for determining electrical statuses of electrical consumers in an electrical network, the disaggregation method comprising:

- measuring an overall electrical parameter of the electrical network (13) by an electrical parameter measuring unit (5),

- applying a filter to the measured overall electrical parameter by a filtering unit (6), - sampling the filtered measured overall electrical parameter by a sampling unit (8),

- providing electrical signatures of the electrical consumers (2, 3, 4) by an electrical signature providing unit (7), wherein the electrical signatures are assigned to the statuses of the electrical consumers, filtered by applying the filter to the electrical signatures and sampled by the sampling unit (8),

- determining the statuses of the electrical consumers (2, 3, 4) depending on the overall electrical parameter and the electrical signatures ,

11. A disaggregation computer program for determining electrical statuses of electrical consumers in an electrical network, the computer program comprising program code means for causing a disaggregation apparatus as defined in claim 1 to carry out the steps of the disaggregation method as defined in claim 10, when the computer program is run on a computer controlling the disaggregation apparatus.