Disaggregation apparatus for being used in a multi-group electrical network

Abstract

The invention relates to a disaggregation apparatus (4) for being used in a multi-group electrical network (5), which comprises multiple electrical groups (1, 2, 3), each comprising one or more appliances (1.sub.1, 1.sub.2, 1.sub.3, 2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3). A determination unit (7) determines an electrical group (1, 2, 3) comprising an appliance, of which an operational state has been changed, based on first changes in mains voltages (V.sub.1, V.sub.2, V.sub.3) measured while the operational state change occurs, second and third changes in the mains voltages (V.sub.1, V.sub.2, V.sub.3) measured while switchable loads (1.sub.n, 2.sub.n, 3.sub.n) are switched, and the resistances (R.sub.1n, R.sub.2n, R.sub.3n) of the switchable loads (1.sub.n, 2.sub.n, 3.sub.n). Thus, a misdetection due to an operational state change of an appliance in another electrical group may be avoided and the accuracy of disaggregation may be improved in a multi-group electrical network (5).

Claims

1. A disaggregation apparatus (4) for being used in a multi-group electrical network (5), which comprises multiple electrical groups (1, 2, 3), each comprising one or more appliances (1.sub.1, 1.sub.2, 1.sub.3, 2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3), and which is powered by a power source (6), wherein the disaggregation apparatus (4) comprises: for each electrical group (1, 2, 3), a voltage meter (1.sub.4, 2.sub.4, 3.sub.4) for measuring a first change in a mains voltage (V.sub.1, V.sub.2, V.sub.3) delivered to the appliances (1.sub.1, 1.sub.2, 1.sub.3, 2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3) of the electrical group (1, 2, 3) while an operational state of an appliance is changed, a control unit (8) for switching, for each electrical group (1, 2, 3), a switchable load (1.sub.n, 2.sub.n, 3.sub.n), wherein, for each electrical group (1, 2, 3), the voltage meter (1.sub.4, 2.sub.4, 3.sub.4) is adapted to measure a second change in the mains voltage (V.sub.1, V.sub.2, V.sub.3) while the switchable load (1.sub.n, 2.sub.n, 3.sub.n) of the electrical group (1, 2, 3) is switched, and wherein, for at least one electrical group (1), the voltage meter (1.sub.4) is adapted to measure a third change in the mains voltage (V.sub.1) while the switchable load (3.sub.n) of another electrical group (3) is switched, and a determination unit (7) for determining the electrical group (1, 2, 3) comprising the appliance, of which the operational state has been changed, based on the measured first changes in the mains voltages (V.sub.1, V.sub.2, V.sub.3), the measured second changes in the mains voltages (V.sub.1, V.sub.2, V.sub.3), the measured third change in the mains voltage (V.sub.1), and the resistances (R.sub.1n, R.sub.2n, R.sub.3n) of the switchable loads (1.sub.n, 2.sub.n, 3.sub.n).

2. The disaggregation apparatus (4) as defined in claim 1, wherein the determination unit (7) is adapted to determine, for each electrical group (1, 2, 3), a change (ΔY.sub.1, ΔY.sub.2, ΔY.sub.3) in a total admittance (Y.sub.1, Y.sub.2, Y.sub.3) of the appliances (1.sub.1, 1.sub.2, 1.sub.3, 2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3) of the electrical group (1, 2, 3) based on the measured first changes in the mains voltages (V.sub.1, V.sub.2, V.sub.3), the measured second changes in the mains voltages (V.sub.1, V.sub.2, V.sub.3), the measured third change in the mains voltage (V.sub.1, V.sub.2, V.sub.3), and the resistances (R.sub.1n, R.sub.2n, R.sub.3n) of the switchable loads (1.sub.n, 2.sub.n, 3.sub.n), and to determine the electrical group (1, 2, 3) comprising the appliance, of which the operational state has been changed, based on the determined changes (ΔY.sub.1, ΔY.sub.2, ΔY.sub.3) in the total admittances (Y.sub.1, Y.sub.2, Y.sub.3).

3. The disaggregation apparatus (4) as defined in claim 2, wherein the determination unit (7) is adapted to determine, for each electrical group (1, 2, 3), the change (ΔY.sub.1, ΔY.sub.2, ΔY.sub.3) in the total admittance (Y.sub.1, Y.sub.2, Y.sub.3) based on the measured first changes in the mains voltages (V.sub.1, V.sub.2, V.sub.3), a first ratio of (i) a sum of an external impedance (Z.sub.0) of the multi-group electrical network (5) and an internal impedance (Z.sub.1, Z.sub.2, Z.sub.3) of the electrical group (1, 2, 3) and (ii) a voltage (V.sub.0) supplied by the power source (6), and a second ratio of (i) the external impedance (Z.sub.0) of the multi-group electrical network (5) and (ii) the voltage (V.sub.0) supplied by the power source (6), wherein the first ratio and the second ratio are determined from the measured second changes in the mains voltages (V.sub.1, V.sub.2, V.sub.3), the measured third change in the mains voltage (V.sub.1), and the resistances (R.sub.1n, R.sub.2n, R.sub.3n) of the switchable loads (1.sub.n, 2.sub.n, 3.sub.n).

4. The disaggregation apparatus (4) as defined in claim 3, wherein the determination unit (7) is adapted to determine from the measured first changes in the mains voltages (V.sub.1, V.sub.2, V.sub.3) first changes (Δ.sub.1(1/V.sub.1), Δ.sub.1(1/V.sub.2), Δ.sub.1(1/V.sub.3)) in the reciprocal mains voltages (1/V.sub.1, 1/V.sub.2, 1/V.sub.3), and to determine, for each electrical group (1, 2, 3), the change (ΔY.sub.1, ΔY.sub.2, ΔY.sub.3) in the total admittance (Y.sub.1, Y.sub.2, Y.sub.3) based on the first ratio, the second ratio, and the first changes (Δ.sub.1(1/V.sub.1), Δ.sub.1(1/V.sub.2), Δ.sub.1(1/V.sub.3)) in the reciprocal mains voltages (1/V.sub.1, 1/V.sub.2, 1/V.sub.3).

5. The disaggregation apparatus (4) as defined in claim 4, wherein the determination unit (7) is adapted to determine the changes (ΔY.sub.1, ΔY.sub.2, ΔY.sub.3) in the total admittances (Y.sub.1, Y.sub.2, Y.sub.3) based on directly solving a system of linear equations.

6. The disaggregation apparatus (4) as defined in claim 4, wherein the determination unit (7) comprises: a noise estimation unit (9) for estimating first noise levels (N) in the first changes (Δ.sub.1(1/V.sub.1), Δ.sub.1(1/V.sub.2), Δ.sub.1(1/V.sub.3)) in the reciprocal mains voltages (1/V.sub.1, 1/V.sub.2, 1/V.sub.3), wherein the determination unit (7) is adapted to determine the changes (ΔY.sub.1, ΔY.sub.2, ΔY.sub.3) in the total admittances (Y.sub.1, Y.sub.2, Y.sub.3) further based on the first noise levels (N) as an estimation that minimizes an error criterion.

7. The disaggregation apparatus (4) as defined in claim 6, wherein the noise estimation unit (7) is adapted to further estimate second noise levels (W) in the first ratios and in the second ratio, wherein the determination unit (7) is adapted to determine the changes (ΔY.sub.1, ΔY.sub.2, ΔY.sub.3) in the total admittances (Y.sub.1, Y.sub.2, Y.sub.3) further based on the second noise levels (W) as an estimation that minimizes an error criterion.

8. The disaggregation apparatus (4) as defined in claim 4, wherein the determination unit (7) is adapted to determine the changes (ΔY.sub.1, ΔY.sub.2, ΔY.sub.3) in the total admittances (Y.sub.1, Y.sub.2, Y.sub.3) based on solving, for each electrical group (1, 2, 3), a system of linear equations under the assumption that only for this electrical group (1, 2, 3) the change (ΔY.sub.1, ΔY.sub.2, ΔY.sub.3) in the total admittance (Y.sub.1, Y.sub.2, Y.sub.3) is different from zero, each solution minimizing an error criterion, and on selecting the solution that results in the smallest error.

9. The disaggregation apparatus (4) as defined in claim 4, wherein the determination unit (7) is adapted to determine, for each electrical group (1, 2, 3), from the measured second change in the mains voltage (V.sub.1, V.sub.2, V.sub.3) a second change (Δ.sub.2(1/V.sub.1), Δ.sub.2(1/V.sub.2), Δ.sub.2(1/V.sub.3)) in the reciprocal mains voltage (1/V.sub.1, 1/V.sub.2, 1/V.sub.3), and to determine the first ratio based on the resistance (R.sub.1n, R.sub.2n, R.sub.3n) of the switchable load (1.sub.n, 2.sub.n, 3.sub.n) of the electrical group (1, 2, 3) and the second change (Δ.sub.2(1/V.sub.1), Δ.sub.2(1/V.sub.2), Δ.sub.2(1/V.sub.3)) in the reciprocal mains voltage (1/V.sub.1, 1/V.sub.2, 1/V.sub.3).

10. The disaggregation apparatus (4) as defined in claim 4, wherein the determination unit (7) is adapted to determine, for the at least one electrical group (1), from the measured third change in the mains voltage (V.sub.1) a third change (Δ.sub.3(1/V.sub.1)) in the reciprocal mains voltage (1/V.sub.1), and to determine the second ratio based on the resistance (R.sub.3n) of the switchable load (3.sub.n) of the other electrical group (3) and the third change (Δ.sub.3(1/V.sub.1)) in the reciprocal mains voltage (1/V.sub.1).

11. The disaggregation apparatus (4) as defined in claim 2, wherein, for each electrical group (1, 2, 3), the voltage meter (1.sub.4, 2.sub.4, 3.sub.4) is adapted to measure the mains voltage (V.sub.1, V.sub.2, V.sub.3) right before and right after the first change in the mains voltage (V.sub.1, V.sub.2, V.sub.3), wherein the determination unit (7) is adapted to determine, for each electrical group (1, 2, 3), a change in the power consumption based on the squared mains voltage (V.sub.1, V.sub.2, V.sub.3) right before or right after the first change in the mains voltage (V.sub.1, V.sub.2, V.sub.3) and the change (ΔY.sub.1, ΔY.sub.2, ΔY.sub.3) in the total admittance (Y.sub.1, Y.sub.2, Y.sub.3).

12. The disaggregation apparatus (4) as defined in claim 1, wherein the disaggregation apparatus (4) comprises the switchable loads (1.sub.n, 2.sub.n, 3.sub.n).

13. A system (10) comprising a multi-group electrical network (5), which comprises multiple electrical groups (1, 2, 3), each comprising one or more appliances (1.sub.1, 1.sub.2, 1.sub.3, 2.sub.i, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3), and which is powered by a power source (6), and a disaggregation apparatus (4) for being used in the multi-group electrical network (5) as defined in claim 1.

14. A disaggregation method for being used in a multi-group electrical network (5), which comprises multiple electrical groups (1, 2, 3), each comprising one or more appliances (1.sub.1, 1.sub.2, 1.sub.3, 2.sub.i, 2.sub.2, 2.sub.3, 3.sub.i, 3.sub.2, 3.sub.3), and which is powered by a power source (6), wherein the disaggregation method comprises: for each electrical group (1, 2, 3), measuring a first change in a mains voltage (V.sub.1, V.sub.2, V.sub.3) delivered to the appliances (1.sub.1, 1.sub.2, 1.sub.3, 2.sub.i, 2.sub.2, 2.sub.3, 3.sub.i, 3.sub.2, 3.sub.3) of the electrical group (1, 2, 3) while an operational state of an appliance is changed, for each electrical group (1, 2, 3), measuring a second change in the mains voltage (V.sub.1, V.sub.2, V.sub.3) while the switchable load (1.sub.n, 2.sub.n, 3.sub.n) of the electrical group (1, 2, 3) is switched, for at least one electrical group (1), measuring a third change in the mains voltage (V.sub.1) while the switchable load (3.sub.n) of another electrical group (3) is switched, and determining the electrical group (1, 2, 3) comprising the appliance, of which the operational state has been changed, based on the measured first changes in the mains voltages (V.sub.1, V.sub.2, V.sub.3), the measured second changes in the mains voltages (V.sub.1, V.sub.2, V.sub.3), the measured third change in the mains voltage (V.sub.1), and the resistances (R.sub.1n, R.sub.2n, R.sub.3n) of the switchable loads (1.sub.n, 2.sub.n, 3.sub.n).

15. A disaggregation computer program for being used in a multi-group electrical network (5), which comprises multiple electrical groups (1, 2, 3), each comprising one or more appliances (1.sub.1, 1.sub.2, 1.sub.3, 2.sub.i, 2.sub.2, 2.sub.3, 3.sub.i, 3.sub.2, 3.sub.3), and which is powered by a power source (6), the computer program comprising program code means for causing a disaggregation apparatus to carry out the steps of the disaggregation method as defined in claim 14, when the computer program is run on a computer controlling the disaggregation apparatus (4).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following drawings:

(2) FIG. 1 shows schematically and exemplarily an embodiment of a disaggregation apparatus for being used in a multi-group electrical network, and

(3) FIG. 2 shows a flowchart exemplarily illustrating an embodiment of a disaggregation method for being used in a multi-group electrical network.

DETAILED DESCRIPTION OF EMBODIMENTS

(4) FIG. 1 shows schematically and exemplarily a system 10 comprising a multi-group electrical network 5 and a disaggregation apparatus 4 for being used in the multi-group electrical network 5. The multi-group electrical network 5 comprises multiple electrical groups 1, 2, 3, each comprising one or more appliances 1.sub.1, 1.sub.2, 1.sub.3, 2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3, and is powered by a power source 6. In FIG. 1, the elements of the disaggregation apparatus 4 are shaded.

(5) The disaggregation apparatus 4 comprises, for each electrical group 1, 2, 3, a voltage meter 1.sub.4, 2.sub.4, 3.sub.4 for measuring a first change in a mains voltage V.sub.1V.sub.2, V.sub.3 delivered to the appliances 1.sub.1, 1.sub.2, 1.sub.3, 2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3 of the electrical group 1, 2, 3 while an operational state of an appliance is changed. The disaggregation apparatus 4 further comprises, for each electrical group 1, 2, 3, a switchable load 1, 2.sub.n, 3.sub.n, wherein, for each electrical group 1, 2, 3, the voltage meter 1.sub.4, 2.sub.4, 3.sub.4 is adapted to measure a second change in the mains voltage V.sub.1, V.sub.2, V.sub.3 while the switchable load 1, 2, 3 of the electrical group 1, 2, 3 is switched, and wherein, for at least one electrical group 1, the voltage meter 1.sub.4 is adapted to measure a third change in the mains voltage V.sub.1 while the switchable load 3.sub.n of another electrical group 3 is switched. The disaggregation apparatus 4 further comprises a determination unit 7 for determining the electrical group 1, 2, 3 comprising the appliance, of which the operational state has been changed, based on the measured first changes in the mains voltages V.sub.1, V.sub.2, V.sub.3, the measured second changes in the mains voltages V.sub.1, V.sub.2, V.sub.3, the measured third change in the mains voltage V.sub.1, and the resistances R.sub.1n, R.sub.2n, R.sub.3n of the switchable loads 1.sub.n, 2.sub.n, 3.sub.n. The appliances 1.sub.1, 1.sub.2, 1.sub.3, 2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3 and the switchable loads 1.sub.n, 2.sub.n, 3.sub.n are parallely connected in the electrical groups 1, 2, 3.

(6) The multi-group electrical network 5, here, comprises an external impedance Z.sub.0, part of which may be attributed to a main circuit breaker (not shown) of the multi-group electrical network 5, and the electrical groups 1, 2, 3 each comprise their own circuit breaker (also not shown), which is modeled as an internal impedance Z.sub.1, Z.sub.2, Z.sub.3. Instead of a circuit breaker, a simple fuse may also be used in some embodiments.

(7) The disaggregation apparatus 4 further comprises a control unit 8 for controlling the elements of the disaggregation apparatus 4, in particular, for controlling the voltage meters 1.sub.4, 2.sub.4, 3.sub.4, the switchable loads 1.sub.n, 2.sub.n, 3.sub.n, and the determination unit 7.

(8) In this embodiment, the determination unit 7 is adapted to determine, for each electrical group 1, 2, 3, a change ΔY.sub.3, ΔY.sub.2, ΔY.sub.3 in a total admittance Y.sub.1, Y.sub.2, Y.sub.3 of the appliances 1.sub.1, 1.sub.2, 1.sub.3, 2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3 of the electrical group 1, 2, 3 based on the measured first changes in the mains voltages V.sub.1, V.sub.2, V.sub.3, the measured second changes in the mains voltages V.sub.1, V.sub.2, V.sub.3, the measured third change in the mains voltage V.sub.1, and the resistances R.sub.1n, R.sub.2n, R.sub.3n of the switchable loads 2.sub.n, 3.sub.n, and to determine the electrical group 1, 2, 3 comprising the appliance, of which the operational state has been changed, based on the determined changes ΔY.sub.1, ΔY.sub.2, ΔY.sub.3 in the total admittances Y.sub.1, Y.sub.2, Y.sub.3.

(9) In particular, the determination unit 7 is adapted to determine, for each electrical group 1, 2, 3, the change ΔY.sub.1, ΔY.sub.2, ΔY.sub.3 in the total admittance Y.sub.1, Y.sub.2, Y.sub.3 based on the measured first changes in the mains voltages V.sub.1, V.sub.2, V.sub.3, a first ratio of (i) a sum of the external impedance Z.sub.0 of the multi-group electrical network 5 and the internal impedance Z.sub.1, Z.sub.2, Z.sub.3 of the electrical group 1, 2, 3 and (ii) a voltage V.sub.0 supplied by the power source 6, and a second ratio of (i) the external impedance Z.sub.0 of the multi-group electrical network 5 and (ii) the voltage V.sub.0 supplied by the power source 6, wherein the first ratio and the second ratio are determined from the measured second changes in the mains voltages V.sub.1, V.sub.2, V.sub.3, the measured third change in the mains voltage V.sub.1, and the resistances R.sub.1n, R.sub.2n, R.sub.3n of the switchable loads 1.sub.n, 2.sub.n, 3.sub.n.

(10) Preferentially, the determination unit 7 is adapted to determine from the measured first changes in the mains voltages V.sub.1, V.sub.2, V.sub.3 first changes Δ.sub.1(1/V.sub.1), Δ.sub.1(1/V.sub.2), Δ.sub.1(1/V.sub.3) in the reciprocal mains voltages 1/V.sub.1, 1/V.sub.2, 1/V.sub.3, and to determine, for each electrical group 1, 2, 3, the change ΔY.sub.1, ΔY.sub.2, ΔY.sub.3 in the total admittance Y.sub.1, Y.sub.2, Y.sub.3 based on the first ratio, the second ratio, and the first changes Δ.sub.1(1/V.sub.1), Δ.sub.1(1/V.sub.2), Δ.sub.1(1/V.sub.3), in the reciprocal mains voltages 1/V.sub.1, 1/V.sub.2, 1/V.sub.3, for example, in accordance with the following equation:

(11) $\begin{array}{cc}{\Delta }_1\left(\frac{1}{V_i}\right)\approx \frac{Z_0+Z_i}{V_0}\Delta Y_i+\underset{j\ne i}{.Math.}\frac{Z_0}{V_0}\Delta Y_j,& \left(1\right)\end{array}$
where the indices i and j relate to the electrical groups 1, 2, 3.

(12) This may also be written in matrix-vector notation as:

(13) $\begin{array}{cc}{\Delta }_1\left(\frac{1}{V}\right)\approx M\Delta Y,& \left(2\right)\end{array}$
where Δ.sub.1(1/V) is a column vector, in which the first changes Δ.sub.1(1/V.sub.i) in the reciprocal mains voltages 1/V.sub.i are stacked, M is a matrix with the first ratios (Z.sub.0+Z.sub.i)/V.sub.0 on the i-th diagonal positions and the second ratio Z.sub.0/V.sub.0 on the off-diagonal positions, and ΔY is a column vector, in which the changes ΔY.sub.i in the total admittances Y.sub.i are stacked.

(14) In this embodiment, the determination unit 7 is adapted to determine the changes ΔY.sub.1, ΔY.sub.2, ΔY.sub.3 in the total admittances Y.sub.1, Y.sub.2, Y.sub.3 based on directly solving a system of linear equations, as given, for example, by equation (1) resp. (2).

(15) This direct solution, which is also known as “zero forcing”, provides an estimation of the changes ΔY.sub.i in the total admittances Y.sub.i—under the assumption that no noise is present in Δ.sub.1(1/V) or M—as follows:

(16) $\begin{array}{cc}\Delta {\hat{Y}}_i=\frac{V_0}{Z_i}\left[{\Delta }_1\left(\frac{1}{V_i}\right)-\frac{\underset{j}{.Math.}\frac{Z_0}{Z_j}{\Delta }_1\left(\frac{1}{V_j}\right)}{1+\underset{j}{.Math.}\frac{Z_0}{Z_j}}\right],& \left(3\right)\end{array}$
where, again, the indices i and j relate to the electrical groups 1, 2, 3 and where the symbol “^” indicates that a value is estimated.

(17) This may also be written in matrix-vector notation as:

(18) $\begin{array}{cc}\Delta \hat{Y}=M^{-1}{\Delta }_1\left(\frac{1}{V}\right),& \left(4\right)\end{array}$
where ΔŶ is a column vector, in which the estimations of the changes ΔY.sub.i in the total admittances Y.sub.i are stacked, M is, again, the matrix with the first ratios (Z.sub.0+Z.sub.i)/V.sub.0 on the i-th diagonal positions and the second ratio Z.sub.0/V.sub.0 on the off-diagonal positions, and Δ.sub.1(1/V) is, again, the column vector, in which the first changes Δ.sub.1(1/V.sub.i) in the reciprocal mains voltages 1/V.sub.i are stacked.

(19) Additionally or alternatively, the determination unit 7 may comprise a noise estimation unit 9 for estimating first noise levels N in the first changes Δ.sub.1(1/V.sub.1), Δ.sub.1(1/V.sub.2), Δ.sub.1(1/V.sub.3) in the reciprocal mains voltages 1/V.sub.1, 1/V.sub.2, 1/V.sub.3, wherein the determination unit 7 may be adapted to determine the changes ΔY.sub.1, ΔY.sub.2, ΔY.sub.3 in the total admittances Y.sub.1, Y.sub.2, Y.sub.3 further based on the first noise levels N as an estimation that minimizes an error criterion, such as a mean square error, for example, in accordance with the following equation:

(20) $\begin{array}{cc}\Delta \hat{Y}={{\mathrm{SM}}^T\left({\mathrm{MSM}}^T+N\right)}^{-1}{\Delta }_1\left(\frac{1}{V}\right).& \left(5\right)\end{array}$

(21) This yields an MMSE (minimum mean square error) estimator of random changes ΔY, in the total admittances Y.sub.i with covariance matrix S, where S.sub.ij=E[ΔY.sub.iΔY.sub.j] is the element on the i-th row and in the j-th column of S, in the presence of noise in the first changes Δ.sub.1(1/V.sub.i) in the reciprocal mains voltages 1/V.sub.i with estimated covariance matrix N, where N.sub.ij=E[n.sub.in.sub.j] is the element on the i-th row and in the j-th column of N, and where n.sub.i and n.sub.j are the estimated measurement noise in Δ.sub.1(1/V.sub.i) and Δ.sub.1(1/V.sub.j), so that the measured values equal Δ.sub.1(1/V.sub.i)+n.sub.i and Δ.sub.1(1/V.sub.j)+n.sub.j.

(22) The estimation of the first noise levels N may be based on estimating, for each electrical group i, the noise level of the mains voltage V.sub.i as the variance σ.sub.i.sup.2 of a number of measurements of the same mains voltage V.sub.i. The noise level n.sub.j of the first change Δ.sub.1(1/V.sub.i) in the reciprocal mains voltage 1/V.sub.i may then be approximated from σ.sub.i.sup.2 as 2σ.sub.i.sup.2/V.sub.i.sup.4.

(23) The noise estimation unit 9 may be adapted to further estimate second noise levels W in the first ratios and in the second ratio, wherein the determination unit 7 may be adapted to determine the changes ΔY.sub.1, ΔY.sub.2, ΔY.sub.3 in the total admittances Y.sub.1, Y.sub.2, Y.sub.3 further based on the second noise levels W as an estimation that minimizes an error criterion, such as a mean square error, for example, in accordance with the following equation:

(24) $\begin{array}{cc}\Delta \hat{Y}={{\mathrm{SM}}^T\left({\mathrm{MSM}}^T+N+W\right)}^{-1}{\Delta }_1\left(\frac{1}{V}\right).& \left(6\right)\end{array}$

(25) This yields also an MMSE estimator in the further presence of noise in the first ratios and in the second ratio, i.e., in the elements of M, with estimated covariance matrix W, where W is a diagonal matrix that incorporates the noise variances K.sub.ij of the estimation of the elements of M as W.sub.ij=δ.sub.ijΣ.sub.kK.sub.ikS.sub.kk, where δ.sub.ij equals 1 if i=j and zero otherwise.

(26) The matrix W may be obtained from the noise of M, here denoted by K, which may be derived from the variances σ.sub.i.sup.2 of the measured mains voltages V.sub.i (see above).

(27) Additionally or alternatively, the determination unit 7 may be adapted to determine the changes ΔY.sub.1, ΔY.sub.2, ΔY.sub.3 in the total admittances Y.sub.1, Y.sub.2, Y.sub.3 based on solving, for each electrical group 1, 2, 3, a system of linear equations under the assumption that only for this electrical group 1, 2, 3 the change ΔY.sub.1, ΔY.sub.2, ΔY.sub.3 in the total admittance Y.sub.1, Y.sub.2, Y.sub.3 is different from zero, each solution minimizing an error criterion, such as a mean square error, and on selecting the solution that results in the smallest error, for example, in accordance with the following equations:

(28) $\begin{array}{cc}\Delta {\hat{Y}}_i=\frac{M_i^T{\Delta }_1\left(\frac{1}{V}\right)}{M_i^T{M}_i},& \left(7\right)\end{array}$
where M.sub.i is the i-th column of M, and

(29) $\begin{array}{cc}{e}_i=.Math.{\Delta }_1\left(\frac{1}{V}\right)-M_i\Delta {\hat{Y}}_i.Math.,& \left(8\right)\end{array}$
where e.sub.i is the respective error and ∥•∥ denotes the Euclidean norm of a vector.

(30) For each electrical group 1, 2, 3, the total admittance Y.sub.1, Y.sub.2, Y.sub.3 is the sum of the admittances Y.sub.11, Y.sub.12, Y.sub.13, Y.sub.21, Y.sub.22, Y.sub.23, Y.sub.31, Y.sub.32, Y.sub.33 of the appliances 1.sub.1, 1.sub.2, 1.sub.3, 2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3 of the electrical group 1, 2, 3. This is indicated in FIG. 1 by the dashed boxes with the reference signs Y.sub.1, Y.sub.2, Y.sub.3. Preferentially, the multi-group electrical network 5 is adapted such that losses in the multi-group electrical network 5 between different appliances 1.sub.1, 1.sub.2, 1.sub.3, 2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3 are negligible. Moreover, preferentially the voltage V.sub.0 supplied by the power source 6, the external impedance Z.sub.0 of the multi-group electrical network 5, and the internal impedances Z.sub.1, Z.sub.2, Z.sub.3 of the electrical groups 1, 2, 3 are constant.

(31) If an appliance changes its operational state, for example, is switched on or off, the total admittances Y.sub.1, Y.sub.2, Y.sub.3 change, wherein the changes ΔY.sub.1, ΔY.sub.2, ΔY.sub.3 in the total admittances Y.sub.1, Y.sub.2, Y.sub.3 are, for example, determined in accordance with equation (1) resp. (2).

(32) The determination unit 7 is adapted to determine, for each electrical group 1, 2, 3, from the measured second change in the mains voltage V.sub.1, V.sub.2, V.sub.3 a second change Δ.sub.2(1/V.sub.1), Δ.sub.2(1/V.sub.2), Δ.sub.2(1/V.sub.3) in the reciprocal mains voltage 1/V.sub.1, 1/V.sub.2, 1/V.sub.3, and to determine the first ratio based on the resistance R.sub.1n=1Y.sub.1n, R.sub.2n=1Y.sub.2nR.sub.3n=1Y.sub.3n of the switchable load 1.sub.n, 2.sub.n, 3.sub.n of the electrical group 1, 2, 3 and the second change Δ.sub.2(1/V.sub.1), Δ.sub.2(1/V.sub.2), Δ.sub.2(1/V.sub.3), in the reciprocal mains voltage 1/V.sub.1, 1/V.sub.2, 1/V.sub.3, for example, in accordance with the following equation:

(33) $\begin{array}{cc}\frac{Z_0+Z_i}{V_0}\approx \pm \left(R_{\mathrm{in}}{\Delta }_2\left(1/V_i\right)\right),& \left(9\right)\end{array}$
where the index i relates to the electrical groups 1, 2, 3 and where the sign “+” indicates that the load is switched on and the sign “−” indicates that the load 1.sub.n, 2.sub.n, 3.sub.n is switched off. Thus, the switchable loads 1.sub.n, 2.sub.n, 3.sub.n are switched on or switched off and the first ratios (Z.sub.0+Z.sub.i)/V.sub.0 are determined, for example, in accordance with equation (9).

(34) The determination unit 7 is further adapted to determine, for the at least one electrical group 1, from the measured third change in the mains voltage V.sub.1 a third change Δ.sub.3(1/V.sub.1) in the reciprocal mains voltage 1/V.sub.1, and to determine the second ratio based on the resistance R.sub.3n=1/Y.sub.3n of the switchable load 3.sub.n of the other electrical group 3 and the third change Δ.sub.3(1/V.sub.1) in the reciprocal mains voltage 1/V.sub.1, for example, in accordance with the following equation:

(35) 0$\begin{array}{cc}\frac{Z_0}{V_0}\approx \pm \left(R_{jn}{\Delta }_3\left(1/V_i\right)\right),& \left(10\right)\end{array}$
where the indices i and j relate to the electrical groups 1, 2, 3 and i≠j. In this example, i equals 1 and j equals 3. The sign “+” then indicates that the load 3.sub.n is switched on and the sign “−” indicates that the load 3.sub.n is switched off. Thus, the switchable load 3.sub.n is switched on or switched off and the second ratio Z.sub.0/V.sub.0 is determined, for example, in accordance with equation (10).

(36) The disaggregation apparatus 4 can be adapted to switch the switchable loads 1.sub.n, 2.sub.n, 3.sub.n, measure the second changes Δ.sub.2(1/V.sub.1), Δ.sub.2(1/V.sub.2), Δ.sub.2(1/V.sub.3) in the reciprocal mains voltages 1/V.sub.1, 1/V.sub.2, 1/V.sub.3, and determine the first ratios (Z.sub.0+Z.sub.i)/V.sub.0 repeatedly at regular intervals or on demand, for example, on demand of a user, in order to update the determination of the first ratios (Z.sub.0+Z.sub.i)/V.sub.0. Likewise, the disaggregation apparatus 4 can be adapted to switch the switchable load 3.sub.n of an electrical group 3, measure the third change Δ.sub.3(1/V.sub.1) in the reciprocal mains voltage 1/V.sub.1 of another electrical group 1, and determine the second ratio Z.sub.0/V.sub.0 repeatedly at regular intervals or on demand, for example, on demand of a user, in order to update the determination of the second ratio Z.sub.0/V.sub.0. These updates are particularly preferred if the multi-group electrical network 5 is not very stable and if, thus, these ratios vary.

(37) For each electrical group 1, 2, 3, the voltage meter 1.sub.4, 2.sub.4, 3.sub.4 is preferentially adapted to measure the mains voltage V.sub.1, V.sub.2, V.sub.3 right before and right after the first change in the mains voltage V.sub.1, V.sub.2, V.sub.3, wherein the determination unit 7 is preferentially adapted to determine, for each electrical group 1, 2, 3, a change in the power consumption based on the squared mains voltage V.sub.1, V.sub.2, V.sub.3 right before or right after the first change in a mains voltage V.sub.1, V.sub.2, V.sub.3 and the change ΔY.sub.1, ΔY.sub.2, ΔY.sub.3 in the total admittance Y.sub.1, Y.sub.2, Y.sub.3, for example, in accordance with the following equation:
ΔP.sub.i=V.sub.i.sup.2ΔY.sub.i,  (11)
where the index i relates to the electrical groups 1, 2, 3 and where V.sub.i is the mains voltage right before the first change in the mains voltage V.sub.i if the real part of ΔY.sub.i is negative, and the mains voltage right after the first change in the mains voltage V.sub.i, if the real part of ΔY.sub.i is positive.

(38) In the following, an embodiment of a disaggregation method for being used in a multi-group electrical network will exemplarily be described with reference to a flowchart shown in FIG. 2.

(39) In step 101, for each electrical group 1, 2, 3, a first change in a mains voltage V.sub.1, V.sub.2, V.sub.3 delivered to the appliances 1.sub.1, 1.sub.2, 1.sub.3, 2.sub.1, 2.sub.2, 2.sub.3, 3.sub.1, 3.sub.2, 3.sub.3 of the electrical group 1, 2, 3 is measured while an operational state of an appliance is changed, in step 102, for each electrical group 1, 2, 3, a second change in the mains voltage V.sub.1, V.sub.2, V.sub.3 is measured while the switchable load 1.sub.n, 2.sub.n, 3.sub.n of the electrical group 1, 2, 3 is switched, in step 103, for at least one electrical group 1, a third change in the mains voltage V.sub.1 is measured while the switchable load 3.sub.n of another electrical group 3 is switched, and in step 104, the electrical group 1, 2, 3 comprising the appliance, of which the operational state has been changed, is determined based on the measured first changes in the mains voltages V.sub.1, V.sub.2, V.sub.3, the measured second changes in the mains voltages V.sub.1, V.sub.2, V.sub.3, the measured third change in the main voltage V.sub.1, and the resistances R.sub.1n, R.sub.2n, R.sub.3n of the switchable loads 1.sub.n, 2.sub.n, 3.sub.n.

(40) Steps 102 and 103 can be performed before step 101, and step 103 can be performed before step 102. In an embodiment, firstly steps 102 and 103 are performed in this order and the ratios (Z.sub.0+Z.sub.i)/V.sub.0 and Z.sub.0/V.sub.0 are determined, and then steps 101 and 104 are repeatedly performed with the same determined ratios (Z.sub.0+Z.sub.i)/V.sub.0 and Z.sub.0/V.sub.0 as described above. In the multi-group electrical network is not very stable, steps 102 and 103 can be performed repeatedly at certain time intervals or on demand, in order to update the ratios (Z.sub.0+Z.sub.i)/V.sub.0 and Z.sub.0/V.sub.0.

(41) The disaggregation apparatus and the disaggregation method are preferentially used for home monitoring and for disaggregating energy usage.

(42) Although in the embodiment described above with reference to FIG. 1, the multi-group electrical network comprises three electrical groups, each comprising three appliances, the multi-group electrical network can, of course, also comprise more or less than three electrical groups and each electrical group can, of course, also comprise more or less than three appliances.

(43) Although in the embodiment described above with reference to FIG. 1, the disaggregation apparatus comprises switchable loads which are controlled by a control unit of the disaggregation apparatus, alternatively, the switchable loads can be elements of the multi-group electrical network, for example, appliances of the multi-group electrical network. Even if the switchable loads are not comprised by the disaggregation apparatus, but by the multi-group electrical network, the control unit is adapted to switch the switchable loads.

(44) Although in the embodiment described above with reference to FIG. 1, the second ratio is determined based on the resistance R.sub.3n of the switchable load 3.sub.n of the third electrical group 3 and the third change Δ.sub.3(1/V.sub.1) in the reciprocal mains voltage 1/V.sub.1 of the first electrical group 1, other combinations are possible. For example, the second ratio can be determined based on the resistance R.sub.2n of the switchable load 2.sub.n of the second electrical group 2 and the third change Δ.sub.3(1/V.sub.3) in the reciprocal mains voltage 1/V.sub.3 of the third electrical group 3.

(45) 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.

(46) 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.

(47) 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.

(48) Determinations like the determination of the electrical group comprising the appliance, of which the operational state has been changed, the determination of a change in the power consumption of the multi-group electrical network, the determination of the ratios (Z.sub.0+Z.sub.i)/V.sub.0 and Z.sub.0/V.sub.0, et cetera performed by one or several units or devices can be performed by any other number of units or devices. The determinations and/or the control of the disaggregation apparatus for being used in a multi-group electrical network in accordance with the disaggregation method for being used in a multi-group electrical network can be implemented as program code means of a computer program and/or as dedicated hardware.

(49) 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.

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

(51) The invention relates to a disaggregation apparatus for being used in a multi-group electrical network, which comprises multiple electrical groups, each comprising one or more appliances. For each electrical group, a voltage meter measures a first change in a mains voltage delivered to the appliances of the electrical group while an operational state of an appliance is changed, and a second change in the mains voltage while a switchable load of the electrical group is switched. For at least one electrical group, the voltage meter measures a third change in the mains voltage while the switchable load of another electrical group is switched. A determination unit determines the electrical group comprising the appliance, of which the operational state has been changed, based on the measured first changes in the mains voltages, the measured second changes in the mains voltages, the measured third change in the mains voltage, and the resistances of the switchable loads. Thus, a misdetection due to a change of an operational state of an appliance in another electrical group may be avoided and the accuracy of disaggregation may be improved in a multi-group electrical network.