Voltage adjustment device

Abstract

To provide a voltage adjustment device that can determine on which of a primary side and a secondary side an electric power substation is located.SOLUTION: In a voltage adjustment device 1 having an adjustment transformer 2 and an on-load tap changer 3, a control unit 4 acquires a primary-side voltage V1 and a secondary-side voltage V2 at a predetermined cycle, calculates the differences between the primary-side voltages and the secondary-side voltages arranged in time series according to the predetermined cycle, detects a moment at which the absolute value of the calculated differences exceeds a threshold determined in advance as a changing timing at which changing of taps tn is performed, calculates an integrated value of the amount of change of the primary-side voltage and an integrated value of the amount of change of the secondary-side voltage in a period including the detected changing timing, and determines on which of a primary side and a secondary side an electric power substation is located on the basis of an integrated difference indicating the difference between the calculated integrated value of the amount of change of the primary-side voltage and integrated value of the amount of change of the secondary-side voltage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a voltage regulator. [Background technology]

[0002] The voltage regulating device includes a series transformer whose secondary winding is connected in series to the distribution line, a regulating transformer whose primary winding is connected in parallel to the distribution line and whose secondary winding has multiple taps, and a tap changer that switches the multiple taps to connect them to the primary winding of the series transformer (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-312612 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the voltage adjustment device disclosed in Patent Document 1 does not take into consideration the efficient determination of whether a substation serving as a power source is located on the primary side or the secondary side.

[0005] The present invention has been made in consideration of the above circumstances, and its object is to provide a voltage regulating device that can efficiently determine whether a substation is located on the primary side or the secondary side. [Means for solving the problem]

[0006] A voltage regulating device according to one embodiment of the present disclosure is a voltage regulating device that is arranged on a distribution line that distributes alternating current from a substation to a load, has a regulating transformer with multiple taps, and automatically adjusts the voltage within the voltage range by switching the taps of the regulating transformer when the voltage of the distribution line deviates from a specified voltage range, and is equipped with a control unit that performs processing related to the taps, and the control unit acquires primary and secondary voltages at a predetermined period, calculates a difference between the primary and secondary voltages that are arranged in time series according to the period, detects the moment when the absolute value of the calculated difference exceeds a predetermined threshold value as a switching timing at which the tap was switched, calculates an integrated value of the amount of change in the primary voltage and an integrated value of the amount of change in the secondary voltage during a period including the detected switching timing, and determines whether the substation is located on the primary side or the secondary side based on an integrated difference that indicates the difference between the calculated integrated value of the amount of change in the primary voltage and the integrated value of the amount of change in the secondary voltage.

[0007] In this embodiment, the voltage regulating device is, for example, a direct switching type SVR (Step Voltage Regulator), and includes a regulating transformer including multiple taps, an on-load tap changer including a common terminal, and a control unit that performs processing related to switching of these taps. When the voltage regulating device is arranged (connected) to a distribution line, it is connected to a primary side distribution line and a secondary side distribution line. That is, when the on-load tap changer and the regulating transformer are arranged (connected) to a distribution line, the on-load tap changer (common terminal) is connected to the primary side distribution line, and the regulating transformer (through tap) is connected to the secondary side distribution line. The control unit acquires the primary voltage value (primary voltage value) and the secondary voltage value (secondary voltage value) from measurement transformers (primary measurement transformer (PT1) and secondary measurement transformer (PT2)) provided on the primary and secondary power distribution lines, respectively, so that they are substantially at the same time (same detection time point) at a predetermined period such as 10 msec. The control unit may associate the acquired primary voltage value and secondary voltage value with the acquisition time point and store them in the storage unit, thereby managing the primary voltage value and secondary voltage value that are substantially at the same time (same detection time point) at the predetermined period in a chronological order. The acquisition period (detection period) of the primary voltage value (primary voltage value) and the secondary voltage value (secondary voltage value) may be determined according to (more than a half cycle) a half cycle of the frequency of the commercial power supply from the substation. For example, when the commercial power frequency is 60 Hz, the acquisition period (detection period) may be 16.667 msec, and when the commercial power frequency is 50 Hz, the acquisition period (detection period) may be 20 msec. Each of the primary side voltage value and the secondary side voltage value acquired and detected by the acquisition period (detection period) may be an average value of effective values ​​(root mean square values ​​(RMS)) acquired at multiple points in time (for example, 12 cycles). In this case, the voltage adjustment device (control unit) may calculate the averaged effective values ​​of each of the primary side voltage value and the secondary side voltage value by performing a moving average process each time the primary side voltage value and the secondary side voltage value are detected, and use the calculated values ​​for various arithmetic processes.The control unit calculates a difference indicating the amount of change over time of the primary side voltage and the secondary side voltage, using each of a plurality of primary side voltages and secondary side voltages arranged in time series, acquired at a predetermined cycle. The control unit detects the timing of tap switching based on the calculated difference, and therefore the detection accuracy (the accuracy of determining whether or not the tap switching has been performed) can be improved. That is, the control unit is configured, for example, with a microcomputer having a memory unit, and a threshold value used for comparison with the calculated difference is stored in the memory unit of the microcomputer. The threshold value may be predetermined based on the model, type, or product specifications of the voltage regulator such as an SVR. The control unit calculates the difference each time it acquires (detects) the primary side voltage value and the secondary side voltage value at a predetermined cycle, and detects the moment when the absolute value of the calculated difference exceeds the threshold value as the timing of tap switching. As a result, the control unit detects the timing of tap switching in synchronization with the timing of acquiring (detecting) the primary side voltage value and the secondary side voltage value, thereby improving the detection accuracy (the accuracy of determining whether tap switching has been performed). Then, the control unit determines whether the substation is located on the primary side or the secondary side based on the difference (accumulated difference: ΣΔΔV12=Σ|ΔV1|-Σ|ΔV2|) between the integrated value of the amount of change in the primary side voltage (Σ|ΔV1|) and the integrated value of the amount of change in the secondary side voltage (Σ|ΔV2|) calculated in the period including the detected switching timing. In this way, since the switching timing can be detected with high accuracy, it becomes possible to compare the measured values ​​(integrated value of the amount of change in the primary side voltage, integrated value of the amount of change in the secondary side voltage) before and after the tap switching in the shortest period including the time of the switching timing, thereby improving the accuracy of the determination of the direction of the substation. Therefore, the period required to obtain measurement values ​​(primary voltage, secondary voltage) before and after tap changing can be shortened, and the measurement points can be reduced, thereby preventing the measurement values ​​from containing noise or external disturbance elements from being mixed in. This reduces the computational load while improving the accuracy of directional determination at the substation.

[0008] In one embodiment of the voltage adjustment device of the present disclosure, the control unit reserves the decision as to whether the substation is located on the primary side or the secondary side when the integrated difference falls within a predetermined judgment threshold range, decides that the substation is located on the secondary side when the integrated difference exceeds the judgment threshold range, and decides that the substation is located on the primary side when the integrated difference falls below the judgment threshold range.

[0009] In this aspect, the control unit is, for example, configured by a microcomputer having a storage unit, and various parameters or constants, such as a judgment threshold width, used in the process of substation direction judgment are stored in advance in the storage unit of the microcomputer. The judgment threshold width is defined as a numerical range (-K to K [Vrms]) with a lower limit value (-K [Vrms]) set from an upper limit value (e.g., K [Vrms (Voltage Root-Mean-Square)]). The judgment threshold width may be determined in advance based on, for example, the type, model, or product specifications of a voltage regulator such as an SVR, depending on the arrangement of the voltage regulator. If the integrated difference (ΣΔΔV12) exceeds the judgment threshold width (exceeds the upper limit value), the control unit determines that the substation is located on the secondary side, and if it is below the judgment threshold width (below the lower limit value), the control unit determines that the substation is located on the primary side. Furthermore, the control unit may reserve the determination without executing the substation direction determination if the integrated difference (ΣΔΔV12) falls within the determination threshold range (greater than or equal to the lower limit and less than or equal to the upper limit). Even when the switching timing of the tap switching is detected in this way, if the integrated difference (ΣΔΔV12) does not deviate from the determination threshold range, the control unit reserves the determination, thereby preventing excessive substation direction determination. The control unit acquires (accepts) the determination threshold range input according to the arrangement of the voltage regulating device and stores it in the memory unit, so that the determination threshold range is set variably, thereby improving the availability of the voltage regulating device.

[0010] In a voltage adjustment device according to one embodiment of the present disclosure, the control unit calculates a voltage ratio between the primary side voltage and the secondary side voltage at the current time, calculates a voltage ratio between the primary side voltage and the secondary side voltage prior to the current time, and subtracts the past voltage ratio from the current voltage ratio to calculate a difference between the primary side voltage and the secondary side voltage arranged in chronological order.

[0011] In this embodiment, the control unit calculates a voltage ratio difference using the voltage ratio of the primary side voltage and the secondary side voltage when calculating the difference between the primary side voltage and the secondary side voltage arranged in time series. The control unit acquires the primary side voltage and the secondary side voltage at a predetermined cycle, and calculates the voltage ratio (V2 / V1) between the primary side voltage (V1) and the secondary side voltage (V2) acquired at substantially the same time point. In this case, the control unit calculates the difference (voltage ratio difference) between the primary side voltage and the secondary side voltage arranged in time series by subtracting the voltage ratio (V2(m-1) / V1(m-1)) between the primary side voltage and the secondary side voltage in the past (obtained last time (the [m-1]th cycle)) from the voltage ratio (V2(m) / V1(m)) between the primary side voltage and the secondary side voltage at the present time (obtained this time (the [m]th cycle)). When tap switching is detected (when tap switching is performed), the difference is assumed to have a value equivalent to the turns ratio deviation for one tap. Therefore, a detection threshold (predetermined threshold) may be determined for this turns ratio deviation for one tap, taking into consideration measurement accuracy and a permissible value of disturbance. When the absolute value of the calculated difference (voltage ratio difference) exceeds the detection threshold (predetermined threshold), the control unit detects the moment when the threshold is exceeded as the timing when tap switching is performed, thereby improving the detection accuracy (accuracy of determining whether tap switching has been performed). When the difference (voltage ratio difference) is a positive value, the control unit may determine that the secondary side has been stepped up with respect to the primary side, and when the difference (voltage ratio difference) is a negative value, the control unit may determine that the secondary side has been stepped down with respect to the primary side. Since the timing at which the tap is changed can be detected with relatively high accuracy in this way, it becomes possible to compare the measurement values ​​(the accumulated value of the change in the primary voltage and the accumulated value of the change in the secondary voltage) before and after the tap change in the shortest period including the time of the change, thereby improving the accuracy of the substation's directional determination.

[0012] In a voltage adjustment device according to one embodiment of the present disclosure, the control unit calculates an amount of change in the primary side voltage by subtracting a past primary side voltage prior to the present time from the primary side voltage at the current time, calculates an amount of change in the secondary side voltage by subtracting a past secondary side voltage prior to the present time from the secondary side voltage at the current time, and calculates the difference between the primary side voltage and the secondary side voltage arranged in chronological order by subtracting the amount of change in the primary side voltage from the amount of change in the secondary side voltage.

[0013] In this embodiment, when calculating the difference between the primary voltage and the secondary voltage arranged in time series, the control unit calculates the amount of change from the past (previously acquired in the [m-1]th cycle) voltage value (V1(m-1), V2(m-1)) to the current (currently acquired in the [m-1]th cycle) voltage value (V1(m), V2(m)) for each of the primary voltage and secondary voltage. That is, the control unit calculates the amount of change (ΔV1) in the primary voltage by subtracting the past (previously acquired in the [m-1]th cycle) primary voltage (V1(m-1)) from the current (currently acquired in the [m-1]th cycle) primary voltage (V1(m)). The control unit calculates a change amount (ΔV2) in the secondary voltage by subtracting the secondary voltage (V2(m-1)) at the past (obtained last time (at the [m-1]th cycle)) from the secondary voltage (V2(m)) at the present time (obtained this time (at the [m]th cycle)). The control unit calculates a difference (voltage change amount difference) between the primary voltage and the secondary voltage arranged in time series by subtracting the change amount (ΔV1) in the primary voltage from the change amount (ΔV2) in the secondary voltage. When the absolute value of the calculated difference (voltage change amount difference) exceeds a detection threshold (a predetermined threshold), the control unit detects the moment when the threshold is exceeded as the timing when the tap was switched. The detection threshold (a predetermined threshold) may be determined based on the step voltage when the rated voltage is applied. By using the difference (voltage change amount difference) and detection threshold (predetermined threshold) calculated in this manner, it is possible to improve the detection accuracy of tap switching (the accuracy of determining whether tap switching has been performed). Furthermore, the control unit may determine that the secondary side has been boosted with respect to the primary side when the difference (voltage change amount difference) is a positive value, and determine that the secondary side has been lowered with respect to the primary side when the difference (voltage change amount difference) is a negative value. Since the timing of tap switching can be detected with relatively high accuracy in this manner, it is possible to compare the measured values ​​(the integrated value of the amount of change in the primary side voltage and the integrated value of the amount of change in the secondary side voltage) before and after the tap switching in the shortest period including the time of the switching timing, and it is possible to improve the accuracy of the determination of the direction of the substation.

[0014] In the voltage regulating device according to one aspect of the present disclosure, the control unit starts calculating an integrated value of the amount of change in each of the primary side voltage and the secondary side voltage when a voltage regulation command related to switching of the tap is output.

[0015] In this embodiment, for example, when the secondary voltage deviates from the secondary target voltage range (dead band), a voltage adjustment command (boost / step-down signal) for bringing the secondary voltage within the target voltage range is output by a voltage adjustment command circuit or a control unit provided in the voltage adjustment device. When a voltage adjustment command for tap switching is output, the control unit starts calculating the integrated values ​​of the changes in the primary voltage and the secondary voltage (calculating the integrated difference), thereby improving the accuracy of the determination of the direction of the substation while reducing the computation load required for the direction determination of the substation. In other words, during a period when a voltage adjustment command is not output, the control unit executes moving average processing of the effective values ​​(RMS) of the primary voltage value and the secondary voltage value detected at a predetermined acquisition period (detection period), making it unnecessary to calculate the integrated difference, and reducing the computation load of the control unit during the entire operation period of the voltage adjustment device.

[0016] In the voltage regulating device according to the aspect of the present disclosure, a period for calculating the integrated values ​​of the amounts of change in the primary side voltage and the secondary side voltage is shorter than a period for outputting the voltage regulation command.

[0017] In this embodiment, the calculation period for the integrated values ​​of the changes in the primary voltage and the secondary voltage includes the time when the tap is switched, and the period for which the integrated values ​​are calculated (calculation period) is shorter than the output period of the voltage adjustment command (e.g., 2 seconds). Therefore, even when calculation of the integrated values ​​of the changes in the primary voltage and the secondary voltage is started in response to the output of the voltage adjustment command, it is possible to shorten the period required to obtain the measured values ​​(primary voltage, secondary voltage) before and after the tap switching, and improve the accuracy of the direction determination of the substation.

[0018] In a voltage regulating device according to an aspect of the present disclosure, a calculation period for the integrated values ​​of the amounts of change in the primary side voltage and the secondary side voltage is equal to or less than five times the cycle.

[0019] In this embodiment, the calculation period of the integrated values ​​of the changes in the primary voltage and the secondary voltage is 5 times or less than the predetermined period (5 cycles or less), and the control unit may perform processing related to the direction determination of the substation using the integrated values ​​of the changes in the primary voltage and the secondary voltage calculated in a period of, for example, 5 periods (5 cycles or less). In this case, the 5 periods (5 cycles or less) include 5 measurement points of the primary voltage and the secondary voltage, and the 5 measurement points may consist of 2 measurement points before and after the time when it is determined that the tap has been switched (the time of switching timing). In this way, it is possible to compare the measurement values ​​(the integrated value of the changes in the primary voltage and the integrated value of the changes in the secondary voltage) before and after the tap switching in a relatively short period that is close to the shortest period including the time of switching timing, and the determination accuracy of the direction determination of the substation can be improved. Effect of the Invention

[0020] It is possible to provide a voltage regulating device that can efficiently determine whether a substation is located on the primary side or the secondary side. [Brief description of the drawings]

[0021] [Figure 1] 1 is a block diagram showing an example of the configuration of a voltage adjusting device according to a first embodiment. [Diagram 2] 13 is a flowchart showing a processing procedure (voltage ratio difference) of a control unit. [Diagram 3] 10 is a flowchart showing a processing procedure (voltage change amount difference) of a control unit according to the second embodiment. [Figure 4] 13 is a flowchart showing a processing procedure (voltage ratio difference in a voltage adjustment command) of a control unit according to the third embodiment. [Diagram 5]13 is a flowchart showing a processing procedure (voltage change amount difference in a voltage adjustment command) of a control unit according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] (Embodiment 1) Hereinafter, the embodiments will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a voltage regulator 1 according to the first embodiment. The voltage regulator 1 is, for example, a direct switching type SVR (Step Voltage Regulator) and is arranged on a single-phase or three-phase power distribution line 100. In this embodiment, the voltage regulator 1 will be described as being arranged on a single-phase power distribution line 100, but as will be described later, even when it is arranged on a three-phase power distribution line 100, various calculation processes are performed based on each line voltage. In a forward power transmission state, the voltage regulator 1 (SVR=Step Voltage Regulator) adjusts the voltage of single-phase AC or three-phase AC supplied from a power source side (substation) on the left side of the paper, and distributes the single-phase AC or three-phase AC to a load side on the right side of the paper via the power distribution line 100. In a reverse power transmission state, the voltage adjustment device 1 adjusts the voltage of single-phase AC or three-phase AC supplied from the load side on the right side of the paper, and distributes the single-phase AC or three-phase AC to the power source side (substation) on the left side of the paper via the distribution line 100.

[0023] The power distribution line 100 on which the voltage adjustment device 1 is arranged includes a primary side power distribution line 100 and a secondary side power distribution line 100, that is, the voltage adjustment device 1 is arranged between the primary side power distribution line 100 and the secondary side power distribution line 100. In this embodiment, the power distribution line 100 connected to the primary side (common terminal tc of the on-load tap changer 3) of the regulating transformer 2 included in the voltage adjustment device 1 is the primary side, and the power distribution line 100 connected to the secondary side (through tap of the on-load tap changer 3) of the regulating transformer 2 is the secondary side. A measurement transformer PT (primary side measurement transformer) that detects the value of the primary side voltage (primary side voltage value) is connected to the primary side power distribution line 100. A measurement transformer PT (secondary measurement transformer) that detects a secondary voltage value (secondary voltage value) is connected to the secondary distribution line 100. A substation (a source substation that supplies power), which is a power source, is connected to the distribution line 100, and it is assumed as an initial setting for the arrangement of the voltage regulator 1 that the substation is connected to the primary side and a load is connected to the secondary side.

[0024] The voltage regulator 1 includes an on-load tap changer 3, a regulating transformer 2, a voltage regulation command circuit 5, and a control unit 4. The on-load tap changer 3 has a common terminal tc, n tap terminals tn (n indicates the tap number (t1, t2, t3, . . . tn)), and a contact that connects the common terminal tc to any of the n tap terminals tn, and a primary side distribution line 100 is connected to the common terminal tc. The on-load tap changer 3 adjusts the primary side voltage (V1) or the secondary side voltage (V2) by switching the tap terminal tn connected to the common terminal tc when a load is connected. One of the n tap terminals tn (in this embodiment) functions as a plain tap (tap 4 in the illustration in this embodiment). The plain tap is connected to the distribution line 100 (secondary side distribution line 100) without passing through a winding.

[0025] The regulating transformer 2 is composed of a single-winding transformer having a plurality of taps (t1 to tn). One end of the tapped winding of the regulating transformer 2 is connected to the first tap terminal tn(t1) of the on-load tap-changer 3. The other end of the tapped winding may be connected to the other distribution line 100 or to the neutral point N. (n - 1) taps are drawn from a predetermined position of a portion closer to one end of the tapped winding, and are respectively connected from the second tap terminal tn(t2) to the nth tap terminal tn of the on-load tap-changer 3. Also, the position of the rth tap (1 < r < n: tap 4 in this figure) of the tapped winding is the position of the through tap, and the secondary distribution line 100 is connected to that position. The on-load tap-changer 3 has a common terminal tc, n tap terminals tn, and a contact for connecting either the common terminal tc or the n tap terminals tn, and the primary distribution line 100 is connected to the common terminal tc. The on-load tap-changer 3 adjusts the primary voltage or the secondary voltage by switching the tap terminal tn connected to the common terminal tc in a state where a load is connected.

[0026] The voltage regulation command circuit 5 includes a voltage regulation relay 51 and an instrument transformer 52. The voltage regulation command circuit 5 monitors the secondary voltage, and when the secondary voltage deviates from the target voltage range (dead band) on the secondary side, outputs a step-up / step-down signal (voltage regulation command) for bringing the secondary voltage within the target voltage range. The voltage regulation device 1 may include a primary voltage regulation device 1 that monitors the primary voltage and a secondary voltage regulation device 1 that monitors the secondary voltage. The voltage regulation relay 51 is composed of, for example, a 90 relay. The voltage regulation relay 51 detects the voltage across the relay, and when the detected voltage is outside the target voltage range, generates a step-up / step-down signal (voltage regulation command) instructing tap switching and outputs it to the control unit 4. When a high voltage is applied to the primary winding of the instrument transformer 52, it transforms the high voltage from the secondary winding into a low voltage according to the turns ratio and outputs it. The instrument transformer 52 functions as a secondary measuring transformer PT (secondary measuring transformer).

[0027] The control unit 4 is configured with, for example, a microcomputer and has a CPU (Central Processing Unit) (not shown) and a storage unit such as a ROM or RAM. The control unit controls voltage adjustment according to a control program prestored in the storage unit such as a ROM. Temporarily generated information may be stored in the RAM. The control unit 4 acquires a step-up / step-down signal (voltage adjustment command) output from the voltage adjustment command circuit 5 (voltage adjustment relay 51), and performs tap switching processing for the on-load tap changer 3 according to the step-up / step-down signal. The control unit 4 acquires the primary voltage (V1) and the secondary voltage (V2) measured at substantially the same time by each of the measurement transformers PT arranged on the primary side or the secondary side, and stores the acquired values ​​of the primary voltage and the secondary voltage together with the acquisition time (detection time) in the storage unit.

[0028] The control unit 4 constantly measures the voltage ratio difference or voltage change difference between the primary side (primary side voltage value: V1) and secondary side (secondary side voltage value: V2) and detects the accurate tap switching timing by determining the moment when the change (slope) exceeds a threshold as the tap switching. The control unit 4 acquires the primary side voltage value (primary side voltage value) and the secondary side voltage value (secondary side voltage value) from the measurement transformer PT at a predetermined period such as 10 msec, and stores them in the memory unit in association with the time of acquisition.

[0029] The voltage ratio difference is defined as Δa_21(m) and is shown by the following formula (1), where m indicates the cycle when the voltage value is periodically acquired.

[0030]

number

[0031] That is, the voltage ratio difference (Δa_21(m)) is obtained by subtracting the value obtained by dividing the secondary side voltage value obtained last time (m-1) by the primary side voltage value from the value obtained by dividing the secondary side voltage value by the primary side voltage value in the effective values ​​(RMS) of the primary side (primary side voltage value: V1) and secondary side (secondary side voltage value: V2) obtained this time (m). The effective value (effective value of the most recent cycle) may be based on voltage data such as the average effective value over a certain period of time, a value calculated using a filter, etc.

[0032] In the above formula (1), when a tap change is detected, the voltage ratio difference (Δa_21(m)) becomes a value equivalent to the turns ratio deviation of one tap, so the detection threshold may be determined taking into consideration the measurement accuracy and the tolerance of disturbance. For example, if the turns ratio deviation of one tap is 0.005 and the tolerance is 20%, a change in the absolute value of the voltage ratio difference of 0.004 or more (detection threshold) is detected as a tap change. If the sign is positive, the secondary side can be detected as being boosted from the perspective of the primary side, and if it is negative, it can be detected as being stepped down. Therefore, the control unit 4 may detect a tap change (detect as an electrical switching timing in tap change) when the absolute value of the derived voltage ratio difference (Δa_21(m)) becomes equal to or greater than the detection threshold (for example, 0.004). Furthermore, when the derived voltage ratio difference (Δa_21(m)) is positive, the control unit 4 determines that the secondary side has been boosted when viewed from the primary side, and when the derived voltage ratio difference (Δa_21(m)) is negative, it determines that the secondary side has been boosted when viewed from the primary side.

[0033] The voltage change difference is defined as ΔΔV_21RMS(m) and is shown by the following formula (2), where m indicates the cycle when the voltage value is periodically acquired.

[0034]

number

[0035] That is, the voltage change difference (ΔΔV_21RMS (m)) is obtained by subtracting the change in the effective value (RMS) of the primary voltage value from the change in the effective value (RMS) of the primary voltage value from the current value to the previous value from the change in the effective value (RMS) of the secondary voltage value from the current value to the previous value. The effective value (effective value of the most recent cycle) may be based on voltage data such as the average effective value over a certain period of time, a value calculated using a filter, etc.

[0036] In the case of the above-mentioned formula (2), the threshold value can be determined in the same manner, based on the step voltage when the rated voltage is applied. For example, if the rated voltage is 6600V, the rated step voltage is 100V, and the allowable voltage range is 6000 to 7200V, the allowable range of the step voltage conversion is 9.1% ≒ 600 / 6600, and if there is a change of 91Vrms or more (detection threshold) in absolute value, it is detected as a tap change. Therefore, the control unit 4 may detect a tap change (detect as an electrical change timing in tap change) when the absolute value of the derived voltage change difference (ΔΔV_21RMS (m)) is equal to or greater than the detection threshold (91Vrms). Furthermore, the control unit 4 determines that the secondary side has been boosted when viewed from the primary side when the derived voltage change difference (ΔΔV_21RMS (m)) is positive, and determines that the secondary side has been lowered when viewed from the primary side when the derived voltage change difference (ΔΔV_21RMS (m)) is negative. The flow of processing using the voltage change amount difference will be described in detail in the second embodiment.

[0037] In this way, the control unit 4 calculates the ratio or amount of change between the primary side voltage and the secondary side voltage acquired at a predetermined cycle. Then, the control unit judges whether or not the tap is being changed based on the ratio or amount of change calculated this time and the ratio or amount of change calculated last time. In a voltage regulator 1 such as an SVR, the on-load tap changer 3 uses mechanical contacts, and it is difficult to identify the electrical switching timing in the tap change from the mechanical operation of the tap change. That is, the tap change signal (boost / buck signal: 34M signal) is output to the on-load tap changer 3, and the mechanical operation of the tap change is performed for about 2 seconds (2 [s]), while the taps before and after the change are in a bridging state (bridging resistor conducting) for an extremely short period of 50 [msec]. In response to this, the control unit 4 determines that a tap change has occurred at the moment when the ratio or amount of change (slope) between the primary side voltage and the secondary side voltage, which is constantly measured at a predetermined period, such as 10 msec, exceeds a predetermined threshold, thereby enabling accurate detection of the electrical switching timing of the tap change.

[0038] Before and after the tap change, the bridge resistor is temporarily conductive. At this time, the voltage drop of the bridge resistor due to the load current may exceed the threshold of the voltage change amount difference or the voltage ratio change amount of the tap change itself. Furthermore, in the case of a three-phase system, the timing of these varies from phase to phase, so if the tap change is determined only by the threshold detection, there is a possibility that one tap change operation will actually be detected multiple times in succession. In contrast, if the threshold is detected multiple times within a specific number of cycles, it may be determined as one detection. The specific number of cycles may be determined based on the actual value or product specifications of the on-load tap changer 3. For example, for an on-load tap changer 3 with an actual measurement value of the switching time of 80 to 100 msec, it may be set to 6 cycles for 60 Hz and 5 cycles for 50 Hz. When the threshold is detected multiple times as described above, for any on-load tap changer 3, the first threshold detection is the conduction of the bridge resistor, and the last threshold detection is the completion of switching. In this way, the control unit 4 detects the tap change operation from start to finish as a series of tap changing operations.

[0039] 2 is a flowchart showing a processing procedure (voltage ratio difference) of the control unit 4. The control unit 4 executes this processing during operation of the on-load tap changer 3 in accordance with a control program (program product) pre-stored in a storage unit such as a ROM.

[0040] The control unit 4 acquires a primary voltage value and a secondary voltage value (S101). The control unit 4 stores the primary voltage value and the secondary voltage value acquired substantially at the same time in the storage unit in association with the acquisition time point. By storing the values ​​in association with the acquisition time point in this manner, it is possible to grasp the change over time in the acquired primary voltage value and secondary voltage value.

[0041] The control unit 4 calculates the voltage ratio difference (S102). The control unit 4 constantly measures (calculates) the voltage ratio (V2 / V1) between the primary side (primary side voltage value: V1) and the secondary side (secondary side voltage value: V2) every time it acquires (detects) the primary side voltage value and the secondary side voltage value. The control unit 4 may store the calculated voltage ratio in the storage unit in association with the calculation time point (the detection time point of the primary side voltage value and the secondary side voltage value) in conjunction with the acquisition (detection) of the primary side voltage value and the secondary side voltage value. This makes it possible to store and manage the change history of the voltage ratio of the primary side voltage value and the secondary side voltage value in synchronization with the detection period (sampling period) of the primary side voltage value and the secondary side voltage value. Using the above-mentioned equation (1), the control unit 4 calculates the voltage ratio difference (Δa_21(m)), which is the difference between the voltage ratio of the primary side voltage value and the secondary side voltage value detected this time (in the [m]th cycle) and the voltage ratio of the primary side voltage value and the secondary side voltage value detected previously (in the [m-1]th cycle).

[0042] The control unit 4 determines whether the absolute value of the voltage ratio difference exceeds a threshold value (S103). The threshold value is stored in a storage unit included in the microcomputer constituting the control unit 4, and may be determined by taking into consideration the measurement accuracy and the allowable value of disturbance for the turns ratio deviation for one tap. In this case, for example, if the turns ratio deviation for one tap is 0.005 and the allowable range is 20%, the threshold value (detection threshold value) may be 0.004 (0.004=0.005*(1-0.2)). The control unit 4 calculates the absolute value of the voltage ratio difference, and determines whether the absolute value (absolute value of the voltage ratio difference) exceeds a threshold value (detection threshold value). The comparison between the absolute value of the voltage ratio difference and the threshold value may be determined based on whether the absolute value of the voltage ratio difference is equal to or greater than the threshold value.

[0043] If the absolute value of the voltage ratio difference does not exceed the threshold (S103: NO), the control unit 4 determines that tap switching has not been performed (S1031). If the absolute value of the voltage ratio difference does not exceed the threshold, the control unit 4 determines that tap switching has not been performed, and performs the loop process again from S101.

[0044] When the absolute value of the voltage ratio difference exceeds the threshold (S103: YES), the control unit 4 determines that the tap has been switched (S104). When the absolute value of the voltage ratio difference exceeds the threshold, the control unit 4 determines that the tap has been switched at the timing of acquiring (detecting) the current primary side voltage value and the secondary side voltage value. That is, the control unit 4 detects the moment when it is determined that the absolute value of the voltage ratio difference exceeds the threshold as the timing of the tap switching (detects it as the electrical switching timing in the tap switching). The control unit 4 may detect, as the timing of the tap switching, a moment included in a period (from the previous (m-1) detection time point to the current (m) detection time point) determined by two detection time points (the current (m) cycle and the previous (m-1) cycle in the detection period) in the primary side voltage value and the secondary side voltage value that are the source of calculation of the voltage ratio difference used for the comparison with the threshold. When detecting tap switching in this way, the control unit 4 may perform a process of determining whether the substation is located on the primary side or the secondary side (substation direction determination).

[0045] The control unit 4 calculates an integrated value of the amount of change in each of the primary side voltage and the secondary side voltage during a period including the detected switching timing (S105). As described above, the control unit 4 stores in the memory unit the effective values ​​(root mean square values ​​(RMS)) of each of the primary side voltage value and the secondary side voltage value detected at a predetermined acquisition period (detection period) in association with the acquisition time point. Furthermore, the control unit 4 calculates the average value of the primary side voltage values ​​at multiple successive acquisition times in a chronological order, and stores the calculated average value in association with the acquisition time point as the primary side voltage value (measured value) at the current time point (latest acquisition time point). The control unit 4 calculates and stores the average value of the secondary side voltage value as well as the primary side voltage value.

[0046] In this way, the control unit 4 continuously performs moving average processing for each of the primary side voltage value and the secondary side voltage value detected at the present time point, using a plurality of primary side voltage values ​​and secondary side voltage values ​​detected at past time points and obtained at a plurality of acquisition periods (detection periods) that are continuous in time series. In performing the moving average processing, the control unit 4 may, for example, calculate a moving average at 12 time points (12 cycles) for each of the effective values ​​(RMS) of the primary side voltage value and the secondary side voltage value. One cycle of the 12 cycles indicates an acquisition period (detection period), and when the commercial power frequency is 60 Hz, one cycle that is the acquisition period (detection period) may be 16.667 msec, and when the commercial power frequency is 50 Hz, one cycle that is the acquisition period (detection period) may be 20 msec.

[0047] When calculating the amount of change in the primary voltage, the control unit 4 calculates the absolute value (|ΔV1|=|V1[n]-V1[n-1]|) of the difference between the primary voltage value (moving average value: V1[n]) at the current time (current acquisition cycle: n) and the primary voltage value (moving average value: V1[n-1]) at the immediately previous acquisition time (previous acquisition cycle: n-1) as the amount of change in the primary voltage. The control unit 4 calculates the amount of change in the secondary voltage (|ΔV2|=|V2[n]-V2[n-1]|) in the same way as the amount of change in the primary voltage.

[0048] In this way, the control unit 4 calculates the absolute value of the difference between the detection values ​​at two adjacent detection times based on the acquisition period (detection period), and calculates each absolute value of the difference between the detection values ​​at a plurality of detection times within the period including the detected switching timing. When specifying the period including the detected switching timing, the control unit 4 may specify a period of five times consisting of two cycles (two times) before and after the time point (m) of the switching timing based on the time point (m) when the tap switching is detected as a reference, as the period including the switching timing, i.e., the period for calculating the amount of change in each of the primary side voltage and the secondary side voltage. In this case, the period of five times is specified (time points [m-2], [m-1], [m], [m+1], [m+2]) by the time point [m-1] immediately before, the time point two before, the time point [m-2] immediately after, and the time point two after [m+2] with the time point [m-2], [m-1], [m], [m+1], [m+2] as the center of the switching timing.

[0049] Regarding the difference (amount of change) of the primary side voltage value, the control unit 4 calculates four differences (amount of change: V1[m-1]-V1[m-2]) consisting of the difference between the second previous time point [m-2] and the immediately previous time point [m-1], the difference between the immediately previous time point [m-1] and the switching timing time point [m], the difference between the switching timing time point [m] and the immediately following time point [m+1], the difference between the immediately following time point [m+1] and the time point two points after [m+2], and stores them in the storage unit in association with each time point. The control unit 4 calculates and stores the difference (amount of change) of the secondary side voltage value in the same way as the difference (amount of change) of the primary side voltage value.

[0050] In this embodiment, a period of five points (five cycles) is exemplified as the period for calculating the amount of change corresponding to the period including the switching timing, but the period is not limited thereto and may be three points (three cycles) or seven points (seven cycles) or more, that is, the period for calculating the amount of change may include points before and after the point [m] of the switching timing. Alternatively, the number of points before and after the point [m] of the switching timing may be different. In addition, by shortening the period, it is possible to suppress the inclusion of measurement values ​​including noise or disturbance elements unrelated to tap switching, and therefore it is possible to improve the determination accuracy of the direction determination of the substation while reducing the calculation load.

[0051] The control unit 4 may accept the number of time points used in performing this process, i.e., the number of time points defining the period for calculating the amount of change, by, for example, input from an operation panel or the like provided in the voltage regulating device 1 and store the accepted number of time points in the storage unit, thereby variably setting the number of time points. In other words, parameters or constants used in various processes, such as the number of time points defining the period for calculating the amount of change, may be variably set based on the installation environment, such as the model, type, and product specifications of the voltage regulating device 1, such as an SVR, or the characteristics of the system to be connected.

[0052] In this way, when applying a period of five points in time (five cycles) including the switching timing as the period for calculating the amount of change, the control unit 4 calculates four amounts of change (differences between adjacent points in time) in each of the primary side voltage and the secondary side voltage. The control unit 4 calculates an integrated value of the multiple calculated amounts of change in each of the primary side voltage and the secondary side voltage. That is, the control unit 4 calculates an integrated value (Σ|ΔV1|) of multiple amounts of change in the primary side voltage and an integrated value (Σ|ΔV2|) of multiple amounts of change in the secondary side voltage, calculated for the period including the switching timing (period for calculating the amount of change).

[0053] In the example of this embodiment, if the period for calculating the amount of change is five points in time (five cycles), the differences (amounts of change) of the four primary voltage values ​​are summed up to calculate the integrated value (Σ|ΔV1|) of multiple amounts of change in the primary voltage as described above. The control unit 4 calculates the integrated value (Σ|ΔV2|) of multiple amounts of change in the secondary voltage calculated for the period including the switching timing (period for calculating the amount of change). In the example of this embodiment, if the period for calculating the amount of change is five points in time (five cycles), the differences (amounts of change) of the four secondary voltage values ​​are summed up to calculate the integrated value (Σ|ΔV2|) of multiple amounts of change in the secondary voltage as described above.

[0054] The control unit 4 calculates an integrated difference indicating the difference between the calculated integrated value of the amount of change in the primary side voltage and the integrated value of the amount of change in the secondary side voltage (S106). The control unit 4 calculates an integrated difference (ΣΔΔV12=Σ|ΔV1|-Σ|ΔV2|) indicating the difference between the integrated value of the amount of change in the primary side voltage and the integrated value of the amount of change in the secondary side voltage by subtracting the integrated value of the amount of change in the secondary side voltage (Σ|ΔV2|) from the calculated integrated value of the amount of change in the primary side voltage (Σ|ΔV1|).

[0055] The control unit 4 judges whether the calculated integrated difference falls within the judgment threshold width (S107). The judgment threshold width is defined as a numerical range with a set upper limit and a set lower limit, and is stored in advance in a storage unit such as a microcomputer constituting the control unit 4. Alternatively, the control unit 4 may acquire (accept) the judgment threshold width input according to the arrangement of the voltage regulator 1, and store it in the storage unit, thereby setting the judgment threshold width to be variably set. The judgment threshold width judges whether the calculated integrated difference (ΣΔΔV12) falls within the judgment threshold width, that is, whether the integrated difference (ΣΔΔV12) is equal to or less than the upper limit of the judgment threshold width and equal to or more than the lower limit of the judgment threshold width.

[0056] If it falls within the judgment threshold width (S107: YES), the control unit 4 reserves the judgment of whether the substation is located on the primary side or the secondary side (S1071). If it is determined that the integrated difference (ΣΔΔV12) falls within the judgment threshold width, the control unit 4 reserves the judgment of whether the substation is located on the primary side or the secondary side, and maintains the judgment result of the previous substation direction judgment. When the control unit 4 reserves the judgment, the fact that it is reserved may be stored in the storage unit in association with the time when this processing was performed. The control unit 4 may perform a correction process to optimize the numerical range of the judgment threshold width when the number of times the judgment is reserved becomes equal to or exceeds a predetermined value within a predetermined period by storing the item of the reserved judgment and the processing time in the storage unit.

[0057] If it does not fall within the judgment threshold range (S107: NO), the control unit 4 determines whether or not the integrated difference exceeds the judgment threshold range (S108). If the integrated difference (ΣΔΔV12) does not fall within the judgment threshold range, that is, if the integrated difference (ΣΔΔV12) deviates from the judgment threshold range, the control unit 4 determines whether or not the integrated difference exceeds the judgment threshold range.

[0058] If the integrated difference exceeds the determination threshold width (S108: YES), the control unit 4 determines that the substation is located on the secondary side (S109). If the integrated difference exceeds the determination threshold width, that is, if the integrated difference (ΣΔΔV12) exceeds the upper limit value of the determination threshold width, the control unit 4 determines that the substation is located on the secondary side.

[0059] If the integrated difference does not exceed the determination threshold width (S108: NO), the control unit 4 determines that the substation is located on the primary side (S1081). If the integrated difference does not exceed (is below) the determination threshold width, that is, if the integrated difference (ΣΔΔV12) is less than the lower limit of the determination threshold width, the control unit 4 determines that the substation is located on the primary side.

[0060] After executing the process of S1031, S1071, S109, or S1081, the control unit 4 performs a loop process to execute the process from S101 again. This allows the control unit 4 to periodically and continuously determine whether or not tap switching has occurred (tap switching presence / absence determination) in synchronization with the acquisition (detection) timing of the primary side voltage value and the secondary side voltage value, that is, according to the detection cycle (sampling cycle) of these voltage values.

[0061] In the present embodiment, the voltage regulator 1 has been described as being disposed on a single-phase power distribution line 100, but the present invention is not limited thereto, and the voltage regulator 1 may be disposed on a three-phase power distribution line 100. In this case (three-phase case), when adjusting each of the line voltages (UV, VW, WU) in three-phase AC, the voltage regulator 1 performs three-phase collective switching in which the tap positions corresponding to each of these line voltages (UV, VW, WU) are the same. Therefore, the control unit 4 may detect the timing at which the tap is switched by calculating the difference between the primary side voltage and the secondary side voltage arranged in time series for any of the line voltages (UV, VW, WU) in the three phases.

[0062] Alternatively, the control unit 4 may calculate the difference between the primary voltage and the secondary voltage arranged in time series for each of the line voltages (UV, VW, WU) in the three phases, and detect the timing of tap switching based on the calculated differences between the line voltages (UV, VW, WU). In this way, when the differences between the line voltages (UV, VW, WU) in the three phases are used for the determination, if all the determination results based on these differences match, the control unit 4 may detect the timing of tap switching based on the result of the match. That is, the control unit 4 may determine that tap switching has been performed when the determination results based on these differences indicate that tap switching has been performed. Alternatively, the control unit 4 may determine that tap switching has been performed when the determination results based on any two of the differences indicate that tap switching has been performed. In this way, by making the determination using the differences between the line voltages (UV, VW, WU) in the three phases, it is expected that the influence of disturbances and the like can be reduced and the determination accuracy can be improved.

[0063] (Embodiment 2) 3 is a flowchart showing a processing procedure (voltage change amount difference) of the control unit 4 according to embodiment 2. The control unit 4 executes this processing during operation of the on-load tap changer 3 in accordance with a control program (program product) pre-stored in a storage unit such as a ROM.

[0064] The control unit 4 acquires a primary side voltage value and a secondary side voltage value (S201). The control unit 4 acquires the primary side voltage value and the secondary side voltage value that are substantially at the same detection time point at a predetermined cycle, and stores the acquired primary side voltage value and secondary side voltage value in association with the acquisition time point (detection time point) in the storage unit of the microcomputer.

[0065] The control unit 4 calculates the voltage change difference (S202). The control unit 4 calculates the change amount (ΔV1) in the primary voltage by subtracting the primary voltage (V1(m-1)) in the past (obtained last time (the m-1th cycle)) from the primary voltage (V1(m)) at the present time (obtained this time (the mth cycle)). The control unit 4 calculates the change amount (ΔV2) in the secondary voltage by subtracting the secondary voltage (V2(m-1)) in the past (obtained last time (the m-1th cycle)) from the secondary voltage (V2(m)) at the present time (obtained this time (the mth cycle)). The control unit 4 uses the above-mentioned equation (2) to subtract the change in the primary voltage (ΔV1) from the change in the secondary voltage (ΔV2) to calculate the voltage change difference (ΔΔV_21RMS (m)), which is the difference between the primary voltage and the secondary voltage arranged in time series.

[0066] The control unit 4 judges whether the absolute value of the voltage change amount difference exceeds the threshold value (S203). The threshold value is stored in a storage unit provided in the microcomputer constituting the control unit 4, and may be determined based on the step voltage (step voltage for one tap) when the rated voltage is applied. In this case, for example, if the rated voltage is 6600V, the rated step voltage is 100V, and the allowable voltage range is 6000 to 7200V, the allowable range of the step voltage conversion is 9.1% ≒ 600 / 6600, and the threshold value (detection threshold value) may be 91Vrms. The control unit 4 calculates the absolute value of the voltage change amount difference, and judges whether the absolute value (absolute value of the voltage change amount difference) exceeds the threshold value (detection threshold value). Regarding the comparison between the absolute value of the voltage change amount difference and the threshold value, it may be judged whether the absolute value of the voltage ratio difference is equal to or greater than the threshold value.

[0067] If the absolute value of the voltage change amount difference does not exceed the threshold (S203: NO), the control unit 4 determines that tap switching has not been performed (S2031). If the absolute value of the voltage change amount difference does not exceed the threshold, the control unit 4 determines that tap switching has not been performed, and performs the loop process again from S201.

[0068] When the absolute value of the voltage change difference exceeds the threshold (S203: YES), the control unit 4 determines that the tap has been switched (S204). When the absolute value of the voltage change difference exceeds the threshold, the control unit 4 determines that the tap has been switched at the timing of acquiring (detecting) the current primary side voltage value and the secondary side voltage value. That is, the control unit 4 detects the moment when it is determined that the absolute value of the voltage change difference exceeds the threshold as the timing of the tap switching (detects it as the electrical switching timing in the tap switching). The control unit 4 may detect the moment included in the period (from the previous (m-1) detection time to the current (m) detection time) determined by two detection time points (the current (m) cycle and the previous (m-1) cycle in the detection period) in the primary side voltage value and the secondary side voltage value that are the calculation source of the voltage change difference used for the comparison with the threshold as the timing of the tap switching.

[0069] The control unit 4 performs the processes from S205 to S2071, S209, or S2081 in the same manner as the processes from S105 to S1071, S109, or S1081 in the first embodiment.

[0070] (Embodiment 3) 4 is a flowchart showing a processing procedure (voltage ratio difference in a voltage adjustment command) of the control unit 4 according to the third embodiment. The control unit 4 performs the processes of S301, 302, 303, 304, and 3031 similarly to the processes of S101, 102, 103, 104, and 1031 in the first embodiment.

[0071] The control unit 4 judges whether a voltage adjustment command for switching the tap has been output (S305). The voltage adjustment command circuit 5 monitors the secondary voltage, and when the secondary voltage deviates from the secondary target voltage range (dead band), generates a voltage adjustment command (boost / step-down signal) for keeping the secondary voltage within the target voltage range and outputs it to the control unit 4. The control unit 4 judges whether a voltage adjustment command for switching the tap has been output based on whether the voltage adjustment command (boost / step-down signal) has been output from the voltage adjustment command circuit 5. The period during which the voltage adjustment command is output (e.g., 2 seconds) is longer than the calculation period for the integrated values ​​of the amounts of change in the primary voltage and the secondary voltage. Therefore, the control unit 4 can perform processing for calculating the integrated values ​​of the amounts of change in the primary voltage and the secondary voltage during the period during which the voltage adjustment command is output. In the illustration of this embodiment, the process of determining whether or not a voltage adjustment command has been output is executed after the process of determining that a tap change has been performed, but this is not limited to this and may be executed before the process of determining that the tap change has been performed.

[0072] If the voltage adjustment command has not been output (S305: NO), the control unit 4 performs a loop process to execute the process from S301 again. If the voltage adjustment command has been output (S305: YES), the control unit 4 performs the process from S306 to S3081, S310, or S3091, similar to the process from S105 to S1071, S109, or S1081 in the first embodiment.

[0073] (Embodiment 4) 5 is a flowchart showing a process procedure (voltage change amount difference in a voltage adjustment command) of the control unit 4 according to the fourth embodiment. The control unit 4 performs processes of S401, 402, 403, 404, and 4031 similarly to the processes of S201, 202, 203, 204, and 2031 of the second embodiment.

[0074] The control unit 4 performs the process of S405 similar to the process of S305 in the third embodiment. If the voltage adjustment command has not been output (S405: NO), the control unit 4 performs the loop process to execute the process from S401 again. If the voltage adjustment command has been output (S405: YES), the control unit 4 performs the process of S406 to S4081, S410 or S4091 similar to the process of S105 to S1071, S109 or S1081 in the first embodiment.

[0075] The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the scope and meaning equivalent to the claims.

[0076] The claims may be combined with each other regardless of the form of reference. The claims include multiple dependent claims that depend on multiple dependent claims. The claims do not include multiple dependent claims that depend on a multiple dependent claim, but multiple dependent claims that depend on a multiple dependent claim may be included. [Explanation of symbols]

[0077] 1 voltage regulator, 2 regulating transformer, 3 on-load tap changer, tc common terminal, tn tap terminal (tap), 4 control unit (microcomputer including memory unit), 5 voltage regulation command circuit, 51 voltage regulation relay, 52 instrument transformer, 100 distribution line, PT measurement transformer

Claims

1. A voltage regulator that is arranged on a distribution line that distributes AC power from a substation to a load, has a regulating transformer with multiple taps, and automatically adjusts the voltage within a specified voltage range by switching the taps of the regulating transformer when the voltage of the distribution line deviates from the specified voltage range, a control unit that processes the tap; The control unit is Acquiring a primary side voltage and a secondary side voltage at a predetermined period; Calculating a difference between a primary voltage and a secondary voltage arranged in a time series according to the period; Detecting a moment when the absolute value of the calculated difference exceeds a predetermined threshold as a switching timing when the tap is switched; Calculating an integrated value of a change in a primary side voltage and an integrated value of a change in a secondary side voltage during a period including the detected switching timing; Based on an integrated difference indicating the difference between the calculated integrated value of the change in the primary voltage and the calculated integrated value of the change in the secondary voltage, it is determined whether the substation is located on the primary side or the secondary side. Voltage regulator.

2. The control unit is When the integrated difference falls within a predetermined judgment threshold width, the judgment as to whether the substation is located on the primary side or the secondary side is withheld; If the integrated difference exceeds the determination threshold width, it is determined that the substation is located on the secondary side; If the integrated difference is below the determination threshold width, it is determined that the substation is located on the primary side. The voltage regulator of claim 1 .

3. The control unit is Calculate the voltage ratio between the current primary voltage and secondary voltage, Calculate the voltage ratio between the primary voltage and the secondary voltage from the past before the present time, The difference between the primary voltage and the secondary voltage arranged in time series is calculated by subtracting the past voltage ratio from the current voltage ratio. The voltage regulator of claim 2 .

4. The control unit is Calculate the amount of change in the primary voltage by subtracting the past primary voltage prior to the present time from the primary voltage at the present time; Calculate the amount of change in the secondary voltage by subtracting the past secondary voltage prior to the present time from the current secondary voltage; The difference between the primary voltage and the secondary voltage arranged in time series is calculated by subtracting the change in the primary voltage from the change in the secondary voltage. The voltage regulator of claim 2 .

5. The control unit starts calculating an integrated value of a change amount of each of a primary side voltage and a secondary side voltage when a voltage adjustment command related to switching of the tap is output. The voltage regulator according to any one of claims 1 to 4.

6. The calculation period for the integrated values ​​of the changes in the primary voltage and the secondary voltage is shorter than the output period of the voltage adjustment command. The voltage regulator according to claim 5 .

7. The calculation period for the integrated values ​​of the changes in the primary voltage and the secondary voltage is 5 times or less than the cycle. The voltage regulator of claim 6.

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