Method and apparatus for identifying an association of phase lines to connections of an electrical device capable of unbalanced-load operation

Abstract

A method for identifying an assignment of phase lines of an electrical distribution grid to connections of an electrical device capable of unbalanced-load operation, wherein the device is connected to a plurality of phase lines of the electrical distribution grid, includes setting target parameters assigned to an unbalanced load profile at each of the connections of the electrical device, detecting a temporal profile of a measurement parameter on each of the plurality of phase lines using a detection circuit, comparing the detected temporal profiles of the measurement parameters with the target parameters of the unbalanced load profile for each of the plurality of phase lines, respectively, and identifying the assignment of the phase lines to the connections on the basis of the comparison.

Claims

1. A method for identifying an assignment of phase lines of an electrical distribution grid to connections of an electrical device capable of unbalanced-load operation, wherein the electrical device is connected to a plurality of phase lines of the electrical distribution grid, comprising: setting target parameters assigned to an unbalanced load profile concurrently at each of the connections of the electrical device as signal forms having temporal profiles that differ from one another, detecting a temporal profile of a measurement parameter on each of the plurality of phase lines using a detection circuit, comparing the detected temporal profiles of the measurement parameters with the target parameters of the unbalanced load profile for each of the plurality of phase lines, respectively, and identifying the assignment of the phase lines to the connections on the basis of the comparison.

2. The method as claimed in claim 1, further comprising signalling a start or an end, or both, of the setting of the target parameters of the unbalanced load profile by the electrical device.

3. The method as claimed in claim 1, wherein the target parameters and/or the measurement parameters are each of an electrical nature and comprise one or more of a current I(t), a voltage U(t), a power P(t), and a phase difference ? between current I(t) and voltage U(t).

4. The method as claimed in claim 1, further comprising signalling a correct assignment or an incorrect assignment of the phase lines to the respective connections on the basis of the comparison.

5. The method as claimed in claim 1, wherein the target parameters of the unbalanced load profile are set during normal operation of the device.

6. The method as claimed in claim 1, wherein the target parameters of the unbalanced load profile are predefined by the device itself or by a controller connected to the device.

7. The method as claimed in claim 1, further comprising conducting a corrective action to an incorrect assignment of the phase lines using a software change of the device itself or of a controller connected to the device.

8. The method as claimed in claim 1, wherein the target parameters of the unbalanced load profile have current amplitudes that are temporally constant within a period ?t of at least 30 s but that differ between the connections.

9. The method as claimed in claim 1, further comprising measuring electrical variables at the connections of the electrical device and using the measured electrical variables in setting the target parameters.

10. The method as claimed in claim 1, wherein signal forms that are set at the connections of the electrical device capable of unbalanced-load operation via the set target parameters are also present at least in a mutually distinguishable shape and in a manner temporally correlated with the target parameters in the measurement parameters that are detected on the phase lines.

11. An apparatus for identifying an assignment of phase lines of an electrical distribution grid to connections of an electrical device configured to provide unbalanced-load operation, comprising: a control circuit configured to set target parameters assigned to an unbalanced load profile concurrently at each of the connections of the electrical device as signal forms having temporal profiles that differ from one another, a detection circuit configured to detect a temporal profile of a measurement parameter on each of the plurality of phase lines of the electrical distribution grid to which the electrical device is connected, respectively, an evaluation circuit configured to compare the detected temporal profiles of the measurement parameters with the set target parameters, wherein the control circuit is further configured to identify the assignment of the phase lines to the connections of the electrical device based on the comparison performed by the evaluation circuit.

12. The apparatus as claimed in claim 11, wherein signal forms that are set at the connections of the device capable of unbalanced-load operation via the set target parameters are also present at least in a mutually distinguishable shape and in a manner temporally correlated with the target parameters in the measurement parameters that are detected on the phase lines.

13. An electrical device configured to provide unbalanced-load operation having a plurality of connections via which the device is able to be connected to a multiplicity of phase lines of an electrical distribution grid, wherein the electrical device comprises an apparatus for identifying an assignment of the phase lines of the electrical distribution grid to the connections, the apparatus comprising: a control circuit configured to set target parameters assigned to an unbalanced load profile concurrently at each of the connections of the electrical device as signal forms having temporal profiles that differ from one another, a detection circuit configured to detect a temporal profile of a measurement parameter on each of the plurality of phase lines of the electrical distribution grid to which the electrical device is connected, respectively, an evaluation circuit configured to compare the detected temporal profiles of the measurement parameters with the set target parameters, wherein the control circuit is further configured to identify the assignment of the phase lines to the connections of the electrical device based on the comparison performed by the evaluation circuit.

14. The electrical device as claimed in claim 13, wherein the electrical device is selected from a group that contains the following device classes: an energy-feeding device, an energy-consuming electrical device, and a device that is both energy-feeding and energy-consuming.

15. The electrical device as claimed in claim 14, wherein the energy-feeding device comprises a photovoltaic (PV) inverter, and the device that is both energy-feeding and energy-consuming comprises a battery inverter.

16. The electrical device as claimed in claim 13, wherein characteristic signal forms that are set at the connections of the device capable of unbalanced-load operation via the set target parameters are also present at least in a mutually distinguishable shape and in a manner temporally correlated with the target parameters in the measurement parameters that are detected on the phase lines.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The following text further explains and describes the disclosure with reference to various embodiments illustrated in the figures.

(2) FIG. 1 shows an apparatus according to the disclosure for identifying an assignment of phase lines of a distribution grid to connections of an electrical device in a first embodiment; and

(3) FIG. 2 shows an illustration of measured parameters in comparison with an unbalanced load profile, which is considered to be known, as a function of time.

(4) FIG. 3 shows an apparatus according to the disclosure for identifying an assignment of phase lines of a distribution grid to connections of an electrical device in a second embodiment.

DETAILED DESCRIPTION

(5) FIG. 1 illustrates an apparatus 10 according to the disclosure for identifying an assignment of phase lines L1, L2, L3 of a distribution grid 3 to connections U, V, W, NL of an electrical device 1 in a first embodiment. The electrical device 1 is by way of example a device 1 that is both energy-feeding and energy-consuming, in particular a bidirectionally operable battery inverter. The device 1 has a plurality of phase connections U, V, W that are connected to phase lines L1, L2, L3 of the electrical distribution grid 3. The device additionally comprises a connection NL, which is connected to a neutral conductor N of the electrical distribution grid 3. The distribution grid 3 is designed, for example, as a domestic distribution grid of a building, which is connected on one side to the public energy supply grid ESG. The device 1 is designed both to feed electric power in the form of an unbalanced load profile into the distribution grid 3 and to draw or to consume electrical energy from the distribution grid 3. Using the electrical energy fed into the distribution grid 3 or drawn from the distribution grid 3, the electrical device 1 is in particular able to discharge or recharge a battery connected thereto (not shown in FIG. 1). An electrical consumer 11 is additionally connected to the distribution grid 3. The consumer 11 is illustrated by way of example as a three-phase consumer that is connected to each of the phase lines L1, L2, L3 and to the neutral conductor N. However, it is also possible for the consumer 11 to be a single-phase or two-phase consumer. In addition to the one consumer 11 that is illustrated, further single-phase or multiphase consumers may furthermore additionally be connected to the distribution grid 3. As an alternative or in addition to the consumer 11, an energy-feeding device may also be connected to the distribution grid 3.

(6) In the case of the electrical device 1, it is intended to uniquely connect each of the connections U, V, W to a specific phase line L1, L2, L3. Specifically, it is intended for a first connection U to be connected to a first phase line L1, for a second connection V to be connected to a second phase line L2 and for a third connection W to be connected to a third phase line L3. As illustrated in FIG. 1, the electrical device 1 with its connections U, V, W is however incorrectly connected to the phase lines L1, L2, L3 of the distribution grid 3. By way of example, although a first connection U is still connected to the first phase line L1 correctly assigned thereto, a second connection V is incorrectly connected to the third phase line L3 and a third connection W is incorrectly connected to the second phase line L2. The connection NL is correctly connected to the neutral conductor N of the distribution grid 3.

(7) In order to identify an assignment of the phase lines L1, L2, L3 to the connections U, V, W of the device 1, an apparatus 10 for control and data exchange is connected to the device 1. The control and data connection is symbolized in FIG. 1 by a dashed line. The apparatus 10 comprises a control circuit or unit 5 and an evaluation circuit or unit 4 connected thereto. The apparatus 10 is connected to a detection circuit or unit 2, which is configured, in one embodiment, to detect a respective electrical parameter 21a, 21b, 21c, for example, a respective temporal profile of the electrical parameters 21a, 21b, 21c (see, e.g., FIG. 2) on each of the plurality of phase lines L1, L2, L3 to which the electrical device 1 is also connected. By way of example, the detection circuit or unit 2 comprises current sensors 2.1, 2.2, 2.3 for detecting currents I1, I2, I3 through the phase lines L1, L2, L3 and voltage sensors 2.4, 2.5, 2.6 in order to determine a voltage of the phase lines L1, L2, L3.

(8) In order to identify an assignment of the phase lines L1, L2, L3 or to determine which of the phase lines L1, L2, L3 is connected to which of the connections U, V, W of the device 1, the apparatus 10, in particular its control circuit unit 5, transmits target parameters 20a, 20b, 20c, assigned to an unbalanced load profile, to the device 1 as target values. In response thereto, the device 1 sets the target parameters 20a, 20b, 20c assigned to the predefined unbalanced load profile at its connections U, V, W. In other words, the device 1 thus generates an electric power flow via the connections U, V, W, which corresponds to the target parameters 20a, 20b, 20c of the predetermined unbalanced load profile. In this case, the device 1 signals a start for running through the target parameters 20a, 20b, 20c to the apparatus 10. Triggered by this signaling, the apparatus 10 drives the detection circuit or unit 2 to perform measurements of current I1, I2, I3 and voltage U1, U2, U3 on each of the phase lines L1, L2, L3. The values measured by the detection circuit or unit 2 are transmitted to the apparatus 10, in particular its evaluation circuit or unit 4, in the form of measurement parameters 21a, 21b, 21c. As explained in more detail in FIG. 2, the evaluation circuit or unit 4 determines a currently existing assignment of the phase lines L1, L2, L3 or their electrical connection to the connections U, V, W of the device 1 by comparing the measurement parameters 21a, 21b, 21c with the target parameters 20a, 20b, 20c of the predefined unbalanced load profile.

(9) FIG. 2 shows graphs of the measurement parameters 21a, 21b, 21c measured on the phase lines L1, L2, L3 in comparison with the target parameters 20a, 20b, 20c, considered to be known because they are predefined, of the unbalanced load profile as a function of time t. By way of example, the comparison is performed on the basis of an electric power P(t) as a target parameter and also as a measurement parameter. The powers P(t) ascertained by the evaluation unit 4 from the measurements of current I1, I2, I3 and voltage U1, U2, U3 for each of the phase lines L1, L2, L3 are illustrated as measurement parameters 21a, 21b, 21c in the individual graphs in each case in the form of solid lines. The powers P(t) predefined for the respective connections U, V, W, that is to say the target parameters 20a, 20b, 20c of the unbalanced load profile, are in each case illustrated in the form of a dashed line. In FIG. 2, the target parameters 20a, 20b, 20c are in this case shown in the graphs of those phase lines L1, L2, L3 in which they would occur if the phase lines L1, L2, L3 were to be assigned correctly to the connections U, V, W. The target parameters 20a, 20b, 20c and measurement parameters 21a, 21b, 21c illustrated in the graphs should each be understood in the sense of an enveloping function or as time-dependent power amplitudes of the otherwise sinusoidal instantaneous electric powers.

(10) The target parameters 20a, 20b, 20c of the unbalanced load profile illustrated by way of example in FIG. 2 have different sawtooth-like power increases or power drops as signal forms for each connection U, V, W. Specifically, the power flow generated by the device 1 via the connection Uthat is to say the target parameter 20ais characterized by a sawtooth-like power drop repeating in a time interval t.sub.sta-t.sub.end. The power flow generated by the device 1 via the connection Vthat is to say the target parameter 20bhas two consecutive sawtooth-like power increases. The power flow generated by the device 1 via the connection Wthat is to say the target parameter 20ccontains a sawtooth-like power increase followed by two sawtooth-like power drops. The power flows generated by the device 1 via the connections V and W as target parameters 20b, 20c also repeat after the time interval t.sub.sta-t.sub.end.

(11) The measurement parameters 21a, 21b, 21c determined on the phase lines L1, L2, L3 by way of the detection circuit or unit 2here the measured electric powers P(t)are compared, by the evaluation circuit or unit 4, with the temporal profiles of the target parameters 20a, 20b, 20c set at the connections U, V, W. By way of example, a comparison of the measurement parameter 21a determined on the first phase line L1 with the target parameter 20a set on the first connection U reveals a temporal match between the sawtooth-like power drops. It may therefore be assumed that the first phase line L1 is connected correctly to the first connection U. On the other hand, a comparison of the measurement parameter 21b determined on the second phase line L2 with the target parameter set on the second connection V does not provide a match between the sawtooth-like power drops or power increases. The same applies to a comparison of the measurement parameter 21c determined on the third phase line L3 with the target parameter 20c set on the third connection W. It may therefore be concluded that the second phase line L2 is notas correctly intendedconnected to the second connection V. It may likewise be concluded that the third phase line L3 is notas intendedconnected to the third connection W assigned thereto. However, the power drops or power increases of the measurement parameter 21b measured on the second phase line L2 match the power drops and power increases of the target parameter 20c set on the third connection W. A corresponding match is also revealed when comparing the measurement parameter 21c determined on the third phase line L3 with the target parameter 20b set on the second connection V. It may be concluded therefrom that the second phase line L2 is incorrectly connected to the third connection W and the third phase line L3 is incorrectly connected to the second connection V. The incorrect assignment of the phase lines L2, L3 to the connections V, W may be signaled by the apparatus 10.

(12) The incorrect assignment may be corrected on the one hand by the electrical connection of the phase lines L2, L3 to the connections W, V being disconnected and reconnected with the correct assignment, for example by a qualified electrical engineer. As an alternative, the incorrect assignment may however also be corrected by a software change on the device 1 itself or on a controller upstream of the device 1. The latter is illustrated schematically in FIG. 1. Certain connection names R, S, T are thus assigned to the connections U, V, W of the device 1 within the software. Specifically, if the phase lines L1, L2, L3 are correctly connected to the connections U, V, W, the connection name R (via the first connection U) is assigned to the first phase line L1, the connection name S (via the second connection V) is assigned to the second phase line L2 and the connection name T (via the third connection W) is assigned to the third phase line L3. In order to correct the resultant incorrect assignment of the connection names S, T to the phase lines L2, L3 via the connections W, V in FIG. 1, within the software of the device 1, the connection name S is assigned to the third connection W and thus to the second phase line L2, and the connection name T is assigned to the second connection V and thus to the third phase line L3. As originally planned and despite the continued incorrect connection of the phase lines L2, L3 to the connections W, V, the connection name S is thereby also linked to the second phase line L2, and the connection name T is linked to the third phase line L3.

(13) The signal forms illustrated in FIG. 2 in the temporal profiles of the target parameters 20a, 20b, 20c (here: the sawtooth-like power increases and power drops) are purely exemplary in nature, and other signal forms are alternatively possible. The signal forms of the target parameters 20a, 20b, 20c should however differ from one another firstly in particular in terms of their shape and/or the point in time at which a signal form occurs, in order to guarantee traceability to the connections U, V, W assigned thereto. Secondly, they should be selected such that they occur within the measurement parameters 21a, 21b, 21c and in particular in a manner overlaid with further variations that are generated by other devices connected to the phase lines L1, L2, L3 of the distribution grid 3, for example, further consumers 11, and are thus able to be identified. This is especially important if the further variations generated by the other devices are not temporally constant signal forms as illustrated in FIG. 2 (that is to say just an offset within the superimposition), but rather are likewise temporally variable variations. In order for the signal forms of the target parameters 20a, 20b, 20c to be able to be identified in the measurement parameters 21a, 21b, 21c, it is possible to adaptively adjust the target parameters on the basis of the further variations detected in any case in the phase lines L1, L2, L3. In other words, the greater the extent to which the further variations occur in the measurement parameters 21a, 21b, 21c, the more pronounced the signal forms of the target parameters 20a, 20b, 20c may also be selected to be. By way of example, it is possible for a certain signal form of the target parameters 20a, 20b, 20c to be repeated at a frequency that is characteristic of the respective connection U, V, W and different from a grid frequency of the distribution grid 3. This signal form may thus also be detected in the measurement parameters 21a, 21b, 21c of the phase lines L1, L2, L3 connected to the connections U, V, W. The measurement parameters 21a, 21b, 21c may be analyzed for the existence of the frequencies characteristic for the connections U, V, W by way of a Fourier transform. The frequencies ascertained in the measurement parameters 21a, 21b, 21c may then be used to infer the target parameters 20a, 20b, 20c corresponding to these frequencies, and thereby the respective connections U, V, W.

(14) FIG. 3 illustrates an apparatus 10 according to the disclosure for identifying an assignment of phase lines L1, L2, L3 of a distribution grid 3 to connections U, V, W of an electrical device 1 in a second embodiment. FIG. 3 corresponds in many of its features to FIG. 1, for which reason reference is made to the description of FIG. 1 with regard to the similar features. Therefore, only the differences between the second embodiment and the embodiment according to FIG. 1 are explained below.

(15) In contrast to FIG. 1, the electrical device 1 of FIG. 3 has a detection apparatus 9 having current sensors 9u, 9v, 9w and voltage sensors (not illustrated in FIG. 3 for the sake of clarity). The detection apparatus 9 is configured to detect currents IU, IV, IW flowing through the outputs U, V, W and voltages UU, UV, UW present at the outputs U, V, W as electrical variables, and communicate the detected electrical variables to the apparatus 10. In contrast to FIG. 1, the device 1 does not receive any information with regard to an unbalanced load profile to be set at its connections U, V, W. By contrast, the device 1 in FIG. 3 itself decides when the method for identifying an assignment of phase lines L1, L2, L3 to the connections U, V, W is started. The method may in this case be performed during normal operation of the device 1, for example when an unbalanced load profile suitable for the method is present or expected at the connections U, V, W of the device 1. If this is the case, then the device 1 signals a start time t.sub.sta for the method to the apparatus 10. The device 1 then, at its connections U, V, W, measures the currents IU, IV, IW flowing through the connections U, V, W and the voltages UU, UV, UW prevailing there in the form of electrical variables. As also described in FIG. 1, the device 1 signals a starting time t.sub.sta of the method at which the detection of the electrical variables begins. Triggered by the signaling of the starting time t.sub.sta by the device 1, the apparatus 10 then drives the detection circuit or unit 2 connected thereto in order to detect measurement parameters 21a, 21b, 21c on the phase lines L1, L2, L3. The detection of the electrical variables at the connections U, V, W of the device 1 and of the measurement parameters 21a, 21b, 21c on the phase lines L1, L2, L3 is performed for a predetermined period or until this is ended by the device 1 or the apparatus 10. The device 1 advantageously likewise signals to the apparatus 10 an end time t.sub.end that ends the detection of the electrical variables at the connections U, V, W or of the measurement parameters 21a, 21b, 21c on the phase lines L1, L2, L3. The device 1 communicates the electrical variables or their temporal profiles to the apparatus 10. The evaluation circuit or unit 4 of the apparatus interprets the communicated electrical variablespossibly after further processing themas target parameters 20a, 20b, 20c of the set unbalanced load profile. Comparison of the target parameters 20a, 20b, 20c of the unbalanced load profile with the measurement parameters 21a, 21b, 21c ascertained on the phase lines L1, L2, L3, and alsoif necessarycorrection of an incorrect assignment of phase lines L1, L2 L3 and connections U, V, W then takes place in a manner analogous to that described in FIG. 2.