COMPENSATION VALUE DETERMINATION PROCEDURE, ESPECIALLY FOR A DISTANCE PROTECTION PROCEDURE

Description

[0001] The invention relates, among other things, to a distance protection method for monitoring a line section of an electrical power supply line, in which current and voltage values ​​are measured, at least one impedance or reactance value is determined using at least one compensation value, and a fault signal is generated if the impedance or reactance value meets a predetermined triggering criterion, in particular if it lies within a predetermined triggering range. Such distance protection methods, which are based on the so-called reactance method, are described, for example, in European patent EP 2 937 704 B1. Another distance protection method is described in European patent application EP 2 083 278 A1.

[0002] The distance protection method known from the aforementioned patent specification requires the input of a compensation value required for the application of the reactance method, which depends on the power supply line to be monitored and its operating or feed-in situation.

[0003] The invention is based on the object of specifying a distance protection method which is particularly user-friendly with regard to the compensation values ​​to be specified for the reactance method.

[0004] This object is achieved according to the invention by a distance protection method having the features according to claim 1. Advantageous embodiments of the distance protection method according to the invention are specified in subclaims.

[0005] According to the invention, it is then provided that a back-calculated compensation value is used as the at least one compensation value or as at least one of the compensation values, which has been determined on the basis of measurement data which have been recorded in the event of a previous fault occurring on the power supply line or a current fault occurring on the power supply line.

[0006] A significant advantage of the distance protection method according to the invention is that it does not require the operator to determine and enter compensation values, since the compensation values ​​are automatically determined by back-calculation, either on the basis of historical fault data before the occurrence of a current fault or on the basis of current fault data during a current fault event.

[0007] It is provided according to the invention if the at least one back-calculated compensation value or at least one of the back-calculated compensation values ​​has been determined by comparing a calculated error characteristic which has been calculated for one or more auxiliary compensation values ​​with the error characteristic actually determined in the case of the previous or current error occurring on the power supply line and by selecting the auxiliary compensation value whose error characteristic has the smallest deviation from the actually determined error characteristic as the back-calculated compensation value to be used in the future.

[0008] The method can be carried out particularly simply and thus advantageously if the at least one back-calculated compensation value or at least one of the back-calculated compensation values ​​has been determined by an iteration method in which, within the framework of iteration steps, an auxiliary compensation value is determined for each iteration step, and the auxiliary compensation value is determined as the iteration result whose error characteristic has the smallest deviation from the actually determined error characteristic, and this iteration result is used as the back-calculated compensation value to be used in the future.

[0009] Quantifiable fault characteristics are preferred. A particularly suitable fault characteristic is the fault distance, for example, the fault distance between a distance protection device implementing the distance protection method and the fault location.

[0010] In the latter embodiment, it is advantageous if the at least one back-calculated compensation value or at least one of the back-calculated compensation values ​​has been determined by comparing one or more calculated error distance values ​​that have been calculated for one or more auxiliary compensation values ​​with the error distance value actually determined for the previous or current fault that occurred on the power supply line and by selecting the auxiliary compensation value whose calculated error distance value has the smallest deviation from the actually determined error distance value as the back-calculated compensation value to be used in the future.

[0011] It is particularly advantageous if, based on the measurement data recorded and stored during a previous or current fault on the power supply line, at least two back-calculated compensation values ​​are determined, namely a first compensation value related to the zero-sequence system and a second compensation value related to the negative-sequence system.

[0012] The first and second back-calculated compensation values ​​are preferably each determined by comparing a calculated fault characteristic calculated for one or more auxiliary compensation values ​​with the fault characteristic actually determined for the previous or current fault occurring on the power supply line and by selecting the auxiliary compensation value whose fault characteristic has the smallest deviation from the actually determined fault characteristic as the back-calculated compensation value to be used in the future.

[0013] It is particularly advantageous if the first and second back-calculated compensation values ​​have each been determined by comparing one or more calculated error distance values, which have been calculated for one or more auxiliary compensation values, with the error distance value actually determined for the previous or current fault that occurred on the power supply line and by selecting the auxiliary compensation value whose calculated error distance value has the smallest deviation from the actually determined error distance value as the back-calculated compensation value to be used in the future.

[0014] The invention also relates to a compensation value determination method for determining at least one compensation value for a distance protection method as described above. According to the invention, with regard to such a compensation value determination method, the at least one compensation value is determined based on measurement data that was recorded (and preferably stored) during a previous or current fault on the power supply line.

[0015] With regard to the advantages of the compensation value determination method according to the invention and advantageous embodiments of the compensation value determination method according to the invention, reference is made to the above statements in connection with the distance protection method according to the invention and its advantageous embodiments.

[0016] In the compensation value determination method according to the invention, the compensation value is determined by comparing a calculated fault characteristic, which has been calculated for one or more auxiliary compensation values, with the fault characteristic actually determined for the previous or current fault occurring on the power supply line and selecting the auxiliary compensation value whose fault characteristic has the smallest deviation from the actually determined fault characteristic as the determined compensation value.

[0017] In the compensation value determination method, the compensation value is preferably determined by comparing one or more calculated fault distance values ​​calculated for one or more auxiliary compensation values ​​with the fault distance value actually determined for the previous or current fault occurring on the power supply line and selecting the auxiliary compensation value whose calculated fault distance value has the smallest deviation from the actually determined fault distance value as the determined compensation value.

[0018] In the compensation value determination method, the back-calculated compensation values ​​for the case of a single-phase conductor-to-earth fault in the x-th phase conductor of the power supply line are preferably calculated in such a way that the deviation between the corresponding fault distance value m and the actually determined fault distance value Msoll is minimal or applies: m = 1 Z ⋅ Im Ulx ⋅ Is ⋅ e jδ ∗ Im Z Z ⋅ Ilx − k 0 ⋅ Ie ⋅ Is ⋅ e jδ ∗ = ! Msoll where: m is the respective calculated fault distance value for the respective auxiliary compensation value δ in the form of a percentage of the total length L of the monitored line section, Ilx is the phase current as a vector quantity in the x-th phase conductor of the power supply line, Ulx is the phase-to-earth voltage of the x-th phase conductor of the power supply line as a vector quantity, Z is the line impedance of the monitored line section of the electrical power supply line, Is is an equivalent current, k0 is an earth adaptation factor characteristic of the electrical power supply line and Msoll is the actually determined fault distance value in the form of a percentage of the total length L of the monitored line section.

[0019] The equivalent current Is is preferably calculated as follows: Is = 1 3 Ilx + Ily + Ilz for the auxiliary compensation values ​​of the zero system and Is = 1 3 Ilx + a 2 ⋅ Ily + a ⋅ Ilz mit a = e j 2 π / 3 for the auxiliary compensation values ​​of the negative sequence system.

[0020] The actually detected fault distance values ​​Msoll can be determined, for example, by inspecting the line after a fault, by two-sided fault location or by traveling wave fault location.

[0021] In the case of a phase-to-phase fault between the x-th and y-th phase conductor of the power supply line, the back-calculated compensation values ​​are preferably calculated in such a way that the deviation between the corresponding fault distance value m and the actually determined fault distance value Msoll is minimal or applies: m = 1 Z ⋅ Im Ulxy ⋅ Is ⋅ e jδ ∗ Im Z Z ⋅ Ilx − Ily ⋅ Is ⋅ e jδ ∗ = ! Msoll where: Ilx is the phase current as a vector quantity in the x-th phase conductor of the power supply line, Ily is the phase current as a vector quantity in the y-th phase conductor of the power supply line and Ulxy is the phase-to-phase voltage as a vector quantity between the x-th and y-th phase conductors of the power supply line,

[0022] The invention also relates to a compensation value determination device for determining at least one compensation value for a distance protection method as described above, or to a distance protection device that can execute a distance protection method as described above. According to the invention, the compensation value determination device is configured such that it determines the at least one compensation value based on measurement data acquired during a previous fault that occurred on the power supply line or a current fault that occurred on the power supply line.

[0023] Regarding the advantages of the compensation value determination device according to the invention and advantageous embodiments of the compensation value determination device according to the invention, reference is made to the above explanations. A particular advantage is that the compensation value determination device can calculate the compensation values ​​automatically, for example, even during the ongoing operation of a distance protection device in which the compensation value determination device can be integrated.

[0024] The invention also relates to a distance protection device. According to the invention, it is provided that this device has a compensation value determination device as described above.

[0025] The invention is explained in more detail below using exemplary embodiments; by way of example, Figure 1 shows an embodiment of a distance protection device according to the invention, on the basis of which a first embodiment of a method according to the invention is explained, and Figure 2 shows a further embodiment of a distance protection device according to the invention, on the basis of which a second embodiment of a method according to the invention is explained.

[0026] In the figures, the same reference symbols are always used for identical or comparable components.

[0027] The Figure 1 shows an embodiment of a distance protection device 10 which is suitable for monitoring a line section 20 of an electrical power supply line 30 and is equipped with an internal compensation value determination function.

[0028] The distance protection device 10 comprises a computing device 11 and a memory 12 in which a software program product SPM is stored, which, when executed by the computing device 11, determines the mode of operation of the distance protection device 10.

[0029] The software program product SPM comprises a fault signal generation module 100, which, when executed by the computing device 11, forms a fault signal generation device. The fault signal generation module 100 is designed to evaluate current operating data, for example in the form of voltage and current values ​​U and I, and to determine a fault impedance or at least a fault reactance X using a back-calculated compensation value δ1 or δ2. If the fault impedance or the fault reactance X lies within a predetermined trigger range, a fault signal FS is generated. Regarding the calculation of a fault reactance X using compensation values ​​δ1 or δ2, the explanations in the patent specification EP 2 937 704 B1 mentioned above can be used, in which calculation formulas for the fault reactance X for different faults are described in detail.

[0030] In addition, in the event of a detected fault, the fault signal generation module 100 can output a relative fault distance value m(δ1, δ2), for example in the form of a percentage of the total length L of the monitored line section 20.

[0031] The software program product SPM also includes a compensation value determination module 110, which, when executed by the computing device 11, forms a compensation value determination device and can determine a first, back-calculated compensation value δ1 related to the zero-sequence system of the power supply line 30 and a second, back-calculated compensation value δ2 related to the negative-sequence system of the power supply line 30. Of the two back-calculated compensation values ​​δ1 and δ2, the compensation value determination module 110 selects one and transmits it to the error signal generation module 100 for further use, in particular for determining the fault reactance X and the relative fault distance value m(δ1, δ2).

[0032] The compensation value determination module 110 comprises a comparison module 111 and an iteration module 112. The iteration module 112 and the comparison module 111 jointly perform an iteration process.

[0033] Within the iteration process, an optimal compensation value δ1 and δ2 is recalculated for the zero-sequence system and for the negative-sequence system, respectively, based on measurement data, preferably current and voltage measurement values ​​Ialt and Ualt, which were recorded during a previous fault on the power supply line 30. The compensation values ​​δ1 and δ2 are recalculated based on at least one quantifiable fault characteristic of the previously occurred fault; for example, it is assumed below that the relative fault distance is used as a quantifiable fault characteristic. Msoll hereinafter refers to the fault distance value actually determined for the previous fault on the power supply line 30 in the form of a percentage of the total length L of the monitored line section 20.

[0034] The current and voltage measured values ​​Ialt and Ualt, which were recorded during the fault that previously occurred on the power supply line 30, can be specifically fed in from outside to carry out the iteration process; alternatively, they can also be read from a memory area 12a of the memory 12, provided they have been temporarily stored there.

[0035] In each i-th iteration step of the iteration process, an auxiliary compensation value δ1i and δ2i is individually determined for the first and second compensation values ​​δ1 and δ2, for which a corresponding relative error distance value m(δ1i) and m(δ2i) is individually calculated based on a line model describing the power supply line 30 or its line section 20. The individually calculated auxiliary compensation value values ​​m(δ1i) and m(δ2) are then compared with the error distance value Msoll actually determined for the error that occurred earlier on the power supply line 30, forming a deviation value |m(δ1i)-Msoll| or |m(δ2i)-Msoll|. For the first and second compensation values, the auxiliary compensation value δ1i and δ2i is selected as the final recalculated compensation value δ1 and δ2, respectively, whose calculated error distance value m(δ1i) orm(δ2i) has the smallest deviation from the actually determined error distance value Msoll.

[0036] Of the two final back-calculated compensation values ​​δ1 and δ2, the compensation value whose back-calculated error distance value has the smaller deviation from the actually determined error distance value Msoll is finally selected; this selected compensation value δ1 or δ2 is forwarded to the error signal generation module 100 for further use as the back-calculated compensation value to be used in the future.

[0037] In the case of a single-phase conductor-to-earth fault in the x-th phase conductor of the power supply line 30, the fault distance values ​​are preferably calculated according to: m δ = 1 Z ⋅ Im Ulx ⋅ Is ⋅ e jδ ∗ Im Z Z ⋅ Ilx − k 0 ⋅ Ie ⋅ Is ⋅ e jδ ∗ mit δ = δ 1 i bzw . δ = δ 2 i where m denotes the respective calculated fault distance value for the respective auxiliary compensation value δ1i or δ2i in the form of a percentage of the total length L of the monitored line section 20. Ilx denotes the phase current as a vector quantity in the x-th phase conductor of the power supply line 30, Ulx the phase-to-earth voltage of the x-th phase conductor of the power supply line 30 as a vector quantity, Z the line impedance of the monitored line section 20 of the electrical power supply line 30, Is an equivalent current and k0 an earth adaptation factor characteristic of the electrical power supply line 30.

[0038] The equivalent current Is is preferably calculated as follows: Is = 1 3 Ilx + Ily + Ilz for the auxiliary compensation values ​​δ1i of the zero system and Is = 1 3 Ilx + a 2 ⋅ Ily + a ⋅ Ilz mit a = e j 2 π / 3 for the auxiliary compensation values ​​δ2i of the negative sequence system.

[0039] The Figure 2shows a further embodiment of a distance protection device 10 which is suitable for monitoring a line section 20 of an electrical power supply line 30 and is equipped with an internal compensation value determination function. In the embodiment according to Figure 2 the distance protection device 10 is connected to another device, for example another distance protection device 10' connected to the other line end of the line section 20, and receives from this - upon detection of a fault in the line section 20 - a current fault distance value Msoll determined by the other distance protection device 10', i.e. determined externally, which relates to the current fault, i.e. the fault occurring during normal monitoring operation of the distance protection device 10.

[0040] The distance protection device 10 evaluates the current operating data, for example in the form of voltage and current values ​​U and I, by means of its compensation value determination module 110, using the currently externally determined fault distance value Msoll and the Figure 1 explained line model to determine back-calculated compensation values ​​δ1 and δ2 and to select one of them for the error signal generation module 100.

[0041] The operation of the compensation value determination module 110 according to Figure 2 can be the operation of the compensation value determination module 110 according to Figure 1 correspond; unlike in Figure 1 Only the current and voltage measured values ​​Ialt and Ualt of a previous fault are not used, but the current current and voltage measured values ​​U and I of the current fault.

[0042] In other words, the design variant differs according to Figure 2from the design variant according to Figure 1 by the fact that during operation an automatic recalculation of optimal compensation values ​​can be carried out based on current errors, whereas in the version according to Figure 1 previous, i.e. old, errors are used.

[0043] Of course, in the sense of a third embodiment, a distance protection device 10 can also be provided, which carries out a first calculation of optimal compensation values ​​based on an old fault according to Figure 1 and then automatically recalculates optimal compensation values ​​during operation based on current errors according to Figure 2 carries out.

[0044] Although the invention has been illustrated and described in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention as defined in the claims. List of reference symbols

[0045] 10Distance protection device 10'Distance protection device 11Computer 12Memory 12aMemory area 20Line section 30Electrical power supply line 100Error signal generation module 110Compensation value determination module 111Comparison module 112Iteration module FSError signal ICurrent values ​​IaltCurrent measured value LTotal length m(δ1, δ2)Relative error distance value m(δ1i)Relative error distance value m(δ2i)Relative error distance value |m(δ1i)-Msoll|Deviation value |m(δ2i)-Msoll|Deviation value MsollActual detected error distance value SPMSoftware program product USVoltage values ​​UaltVoltage measured value XError reactance(value) δ1Compensation value δ2Compensation value δ1iAuxiliary compensation value δ2iAuxiliary compensation value

Claims

1. Distance protection method for monitoring a line section (20) of an electrical power supply line (30), in which - current and voltage values (I, U) are measured and an impedance or reactance value (X) of the power supply line (30) is determined using at least one compensation value (δ1, δ2), and - a fault signal (FS) is generated when the impedance or reactance value (X) meets a predetermined trigger criterion, wherein a back-calculated compensation value which has been determined on the basis of measurement data which have been acquired in the case of a previous fault occurring on the power supply line (30) or a current fault occurring on the power supply line (30) is used as the at least one compensation value (61, δ2) or as at least one of the compensation values (61, δ2), characterized in that the at least one back-calculated compensation value (δ1, δ2) or at least one of the back-calculated compensation values has been determined - by comparing a calculated fault characteristic which has been calculated for one or more auxiliary compensation values (δ1i, δ2i) with the fault characteristic actually detected in the previous or current fault occurring on the power supply line (30), and - by selecting the auxiliary compensation value (61i, δ2i) whose fault characteristic has the smallest deviation from the actually detected fault characteristic as the back-calculated compensation value to be used in the future.

2. Distance protection method according to any one of the preceding claims, characterized in that the at least one back-calculated compensation value (δ1, δ2) or at least one of the back-calculated compensation values has been determined - by means of an iteration method in which a respective auxiliary compensation value (δ1i, δ2i) is determined for each iteration step in the context of iteration steps, and - the auxiliary compensation value (61i, δ2i) whose fault characteristic has the smallest deviation from the actually detected fault characteristic is determined as the iteration result and this iteration result is further used as the back-calculated compensation value to be used in the future.

3. Distance protection method according to any one of the preceding claims, characterized in that the at least one back-calculated compensation value (δ1, δ2) or at least one of the back-calculated compensation values has been determined - by comparing one or more calculated fault distance values (m(δ1i), m(δ2i)) which have been calculated for one or more auxiliary compensation values (δ1i, δ2i) with the fault distance value (Msoll) actually detected in the previous or current fault occurring on the power supply line (30), and - by selecting the auxiliary compensation value whose calculated fault distance value has the smallest deviation from the actually detected fault distance value as the back-calculated compensation value to be used in the future.

4. Distance protection method according to any one of the preceding claims, characterized in that the measured data which have been acquired and stored in the case of a previous or current fault occurring on the power supply line (30) are taken as a basis for determining at least two back-calculated compensation values, namely a first compensation value referred to the zero phase-sequence system and a second compensation value referred to the negative phase-sequence system.

5. Distance protection method according to Claim 4, characterized in that the first and second back-calculated compensation values have each been determined - by comparing a calculated fault characteristic which has been calculated for one or more auxiliary compensation values with the fault characteristic actually detected in the previous or current fault occurring on the power supply line (30), and - by selecting the auxiliary compensation value whose fault characteristic has the smallest deviation from the actually detected fault characteristic as the back-calculated compensation value to be used in the future.

6. Distance protection method according to any one of the preceding claims, characterized in that the first and second back-calculated compensation values have each been determined - by comparing one or more calculated fault distance values which have been calculated for one or more auxiliary compensation values with the fault distance value actually detected in the previous or current fault occurring on the power supply line (30), and - by selecting the auxiliary compensation value whose calculated fault distance value has the smallest deviation from the actually detected fault distance value as the back-calculated compensation value to be used in the future.

7. Compensation value determination method for determining at least one compensation value for a distance protection method according to any one of the preceding claims, wherein the at least one compensation value is determined on the basis of measurement data which have been acquired in the case of a previous fault occurring on the power supply line (30) or which are acquired in the case of a current fault occurring on the power supply line (30), characterized in that the compensation value is determined - by comparing a calculated fault characteristic which has been calculated for one or more auxiliary compensation values with the fault characteristic actually detected in the previous or current fault occurring on the power supply line (30), and - selecting the auxiliary compensation value whose fault characteristic has the smallest deviation from the actually detected fault characteristic as the determined compensation value.

8. Compensation value determination method according to any one of the preceding Claims 6 to 7, characterized in that the compensation value is determined - by comparing one or more calculated fault distance values which have been calculated for one or more auxiliary compensation values with the fault distance value actually detected in the previous or current fault occurring on the power supply line (30), and - selecting the auxiliary compensation value whose calculated fault distance value has the smallest deviation from the actually detected fault distance value as the determined compensation value.

9. Distance or compensation value determination method according to any one of the preceding claims, characterized in that the back-calculated compensation values for the case of a single-phase conductor-earth fault in the x-th phase conductor of the power supply line (30) are each calculated in such a way that the deviation between the corresponding fault distance value m and the actually detected fault distance value Msoll is minimal or the following holds true: m = 1 Z ⋅ Im Ulxy ⋅ Is ⋅ e jδ ∗ Im Z Z ⋅ Ilx − Ily ⋅ Is ⋅ e jδ ∗ = ! Msoll wherein: - m denotes the respective calculated fault distance value for the respective auxiliary compensation value δ in the form of a percentage of the total length L of the monitored line section (20), - Ilx denotes the conductor current as a phasor variable in the x-th phase conductor of the power supply line (30), - Ulx denotes the conductor-earth voltage of the x-th phase conductor of the power supply line (30) as a phasor variable, - Z denotes the line impedance of the monitored line section (20) of the electrical power supply line (30), - Is denotes a replacement current, - k0 denotes an earth adaptation factor characteristic of the electrical power supply line (30), and - Msoll denotes the actually detected fault distance value in the form of a percentage of the total length L of the monitored line section (20).

10. Distance or compensation value determination method according to any one of the preceding claims, characterized in that the back-calculated compensation values fault distance values for the case of conductor-conductor fault in the x-th and y-th phase conductors of the power supply line (30) are each calculated in such a way that the deviation between the corresponding fault distance value m and the actually detected fault distance value Msoll is minimal or the following holds true: m = 1 Z ⋅ Im Ulx ⋅ Is ⋅ e jδ ∗ Im Z Z ⋅ Ilx − k 0 ⋅ Ie ⋅ Is ⋅ e jδ ∗ = ! Msoll wherein: - m denotes the respective calculated fault distance value for the respective auxiliary compensation value δ in the form of a percentage of the total length L of the monitored line section (20), - Ilx denotes the conductor current as a phasor variable in the x-th phase conductor of the power supply line (30), - Ily denotes the conductor current as a phasor variable in the y-th phase conductor of the power supply line (30), - Ulxy denotes the conductor-conductor voltage as the phasor variable between the x-th and y-th phase conductors of the power supply line (30), - Z denotes the line impedance of the monitored line section (20) of the electrical power supply line (30), - Is denotes a replacement current calculated according to ??? and - Msoll denotes the actually detected fault distance value in the form of a percentage of the total length L of the monitored line section (20).

11. Compensation value ascertaining device (110) for determining at least one compensation value for a distance protection method according to any one of the preceding claims or a distance protection unit which can carry out a distance protection method according to any one of the preceding claims, wherein said device or unit is designed in such a way that it determines the at least one compensation value on the basis of measurement data which have been detected and stored in the case of a previous fault occurring on the power supply line (30) or a current fault occurring on the power supply line (30), characterized in that the compensation value is determined - by comparing a calculated fault characteristic which has been calculated for one or more auxiliary compensation values with the fault characteristic actually detected in the previous or current fault occurring on the power supply line (30), and - selecting the auxiliary compensation value whose fault characteristic has the smallest deviation from the actually detected fault characteristic as the determined compensation value.

12. Distance protection unit (10), characterized in that said unit comprises a compensation value ascertaining device (110) according to Claim 11.