JP7393965B2 - voltage regulator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a voltage regulator that transforms and adjusts a three-phase AC voltage of a power distribution line in a power distribution system.

There are two types of voltage regulators that adjust the voltage of distribution lines: a direct switching type, in which the current in the windings of a transformer directly connected to the distribution line passes through a tap changer at the time of load, and a series transformer. There is an indirect switching type in which the wires are connected so that the current flowing through the excitation winding (primary winding) passes through a tap changer at the time of load.

Indirect switching voltage regulators consist of a series transformer in which the secondary winding is connected in series to the distribution line, and a primary winding connected in parallel to the distribution line, with multiple taps provided on the secondary winding. and an on-load tap changer that switches the plurality of taps and connects them to the primary winding of the series transformer.

This on-load tap changer has a plurality of changeover switches for changing the taps connected to the primary winding of the series transformer, and by turning these switches on and off in a predetermined sequence, it changes from the regulating transformer to the series transformer. Switch the magnitude and polarity of the regulated voltage applied to the primary winding of the device.

The control unit that controls turning on and off the changeover switch measures the voltage on the primary side, which is the power supply side, and the voltage on the secondary side, which is the load side, of the distribution line, and adjusts the voltage on the secondary side based on the measurement results. is controlled so that it approaches the reference voltage. Such measurement of the voltage on the primary side and the secondary side is indispensable, especially when considering voltage adjustment during reverse transmission due to system switching.

For example, Patent Document 1 includes a transformer having a plurality of taps, a tap changer, and an instrument transformer that detects voltages on the primary side and secondary side of the transformer. A voltage adjustment device is described that adjusts the voltage on the secondary side to a certain voltage range based on the voltage.

JP2016-208640A

However, the high-voltage measuring transformer used to measure the voltage on the primary side and the secondary side has a problem in that it is expensive.

The present invention has been made in view of the above circumstances, and its purpose is to provide an indirect switching type voltage regulator capable of calculating the voltage on either the primary side or the secondary side. It's about doing.

A voltage regulator according to one aspect of the present invention includes a series transformer in which a secondary winding is connected in series to a distribution line that distributes three-phase AC voltage, and a primary winding is connected in parallel to the distribution line. and an on-load tap switching transformer that switches the tap of a secondary winding and connects it to the primary winding of the series transformer, the voltage regulator comprising: a connection position of the series transformer on the distribution line; a first acquisition unit that acquires a measured voltage from a first measurement transformer that measures the voltage on one side of the transformer; and a first acquisition unit that measures the voltage applied to the primary winding of the series transformer by the on-load tap change transformer. a second acquisition section that acquires a measured voltage from a second measurement transformer; and a second acquisition section that acquires a measured voltage from a second measurement transformer; and a calculation unit that calculates the voltage on the other side.

In this aspect, the primary winding of a series transformer has a secondary winding connected in series to the distribution line, while the secondary winding of an on-load tap-change transformer has a primary winding connected in parallel to the distribution line. Adjustment voltage is applied from the tap of the next winding. Calculate the voltage on the other side of the connection position on the distribution line based on the measurement result of the voltage on one side of the connection position of the series transformer and the measurement result of the voltage applied to the primary winding of the series transformer. Therefore, there is no need for a measuring transformer to measure the voltage on the other side.

In the voltage regulating device according to one aspect of the present invention, the calculation unit calculates a voltage obtained by multiplying the measured voltage acquired by the first acquisition unit by the turns ratio of the first measurement transformer, and the second acquisition unit The voltage on the other side is calculated based on the obtained measured voltage multiplied by the turns ratio of the second measurement transformer and the reciprocal of the turns ratio of the series transformer.

In this aspect, the voltage obtained by multiplying the measurement result of the voltage on one side by the turns ratio of the measurement transformer that measures the voltage and the measurement result of the voltage of the primary winding of the series transformer are multiplied by the voltage. In order to calculate the voltage on the other side of the above connection position based on the turns ratio of the measuring transformer to be measured and the voltage multiplied by the reciprocal of the turns ratio of the series transformer, each measurement result and the turns ratio of each transformer are calculated. The voltage on the other side can be easily calculated based on .

In the voltage regulator according to one aspect of the present invention, the value of the turns ratio of the second measurement transformer is a value obtained by multiplying the turns ratio of the first measurement transformer by the turns ratio of the series transformer. ,
The calculation unit calculates the voltage of the other side based on a voltage obtained by multiplying each of the measurement voltage acquired by the first acquisition unit and the measurement voltage acquired by the second acquisition unit by the turns ratio of the first measurement transformer. The voltage is calculated.

In this aspect, the value of the turns ratio of the measuring transformer that measures the voltage of the primary winding of the series transformer is set to the turns ratio of the measuring transformer that measures the voltage on one side of the series transformer. By setting the value to be a value multiplied by the reciprocal of the turns ratio, the voltage on the other side can be easily calculated based on each measurement result and the turns ratio of one measuring transformer.

The calculation unit calculates the line voltage of one of the two phases on the one side from the measured voltage acquired by the first acquisition unit, and calculates the line voltage of the two phases from the measured voltage of each of the two phases acquired by the second acquisition unit. The difference between the voltages induced in the secondary windings of the respective phases is calculated, and the line voltage of the two phases on the other side is calculated based on the calculated line voltage and the calculated difference.

In this aspect, the line voltage of one of the two phases is calculated from the measurement result of the voltage on one side, and the line voltage of the two phases is calculated from the measurement result of the voltage applied to the primary winding of the series transformer. The line voltage on the other side can be easily calculated based on the difference in voltage induced in the secondary winding of the series transformer.

According to the present invention, it is possible to calculate the voltage on either the primary side or the secondary side.

1 is a block diagram showing a configuration example of a voltage regulator according to a first embodiment. FIG. FIG. 2 is a circuit diagram showing a configuration example of a changeover switch. It is a chart showing the relationship between the tap position and the changeover switch to be turned on for the OU phase. FIG. 2 is an explanatory diagram showing the relationship between the voltage of a power distribution line and the voltage applied to a primary winding of a series transformer. FIG. 2 is an explanatory diagram showing the relationship between the voltage detected by the measurement transformer and the voltage in the distribution line. It is a flowchart which shows the processing procedure of the control part which calculates the voltage on the power supply side. FIG. 2 is a block diagram illustrating a configuration example of a voltage regulator according to a second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof.
(Embodiment 1)
FIG. 1 is a block diagram showing a configuration example of a voltage regulator 100 according to the first embodiment. A voltage regulator (SVR=Step Voltage Regulator) 100 adjusts the U-phase, V-phase, and W-phase AC voltages supplied from the power supply on the left side of the page, and connects the distribution lines 1u, 1v, and 1w to the loads on the right side of the page. U-phase, v-phase, and w-phase alternating current voltages are distributed through the power supply.

Voltage regulator 100 includes a series transformer 1 in which secondary windings 112, 122, 132 are connected in series to power distribution lines 1u, 1v, 1w, respectively, and primary windings 211, 221 to power distribution lines 1u, 1v, 1w. , 231 are Δ-connected. The voltage regulator 100 further includes an on-load tap changer (hereinafter referred to as (simply referred to as a tap changer) 3. The tap changer 3 and the regulation transformer 2 constitute an on-load tap change transformer 200 .

In the series transformer 1, primary windings 111, 121, 131 correspond to secondary windings 112, 122, 132, respectively. The primary windings 111, 121, and 131 are Δ-connected. It is assumed that the terminals of the primary windings 111, 121, 131 corresponding to the load-side terminals of the secondary windings 112, 122, 132 are u1, v1, w1. Further, the terminals of the primary windings 111, 121, 131 corresponding to the power supply side terminals of the secondary windings 112, 122, 132 are designated as u2, v2, w2.

In the regulating transformer 2, a primary winding 211 is connected between power distribution lines 1u and 1v, a primary winding 221 is connected between power distribution lines 1v and 1w, and a primary winding 231 is connected between power distribution lines 1w and 1u. Secondary windings 212, 222, 232 correspond to the primary windings 211, 221, 231, respectively.

Each of the secondary windings 212, 222, 232 has taps t1 and t4 drawn out from one end and the other end, and intermediate taps t2 and t3 drawn out from between the one end and the other end. Each of the secondary windings 212, 222, 232 has one of the taps t1 to t4 connected to the terminals u2, v2, w2 on the primary side of the series transformer 1 via the tap changer 3, and the terminals v1, w1, u1, and one of the others is connected to ground as a neutral point N. That is, the secondary windings 212, 222, 232 of the regulating transformer 2 are Y-connected via the tap changer 3.

In order to measure the voltage applied to the primary windings 211, 221, 231 of the regulating transformer 2, the distribution lines 1u, 1v, 1w are equipped with measuring transformers PT1, PT2 (corresponding to the first measuring transformer). are V-connected. That is, the primary winding of the measuring transformer PT1 is connected between the distribution lines 1u and 1v on the load side of the connection position of the series transformer 1 on the distribution lines 1u, 1v, and 1w. The primary winding of the measuring transformer PT2 is connected between 1w and 1w. For example, the secondary windings of the measurement transformers PT1 and PT2 are regarded as a three-phase balanced circuit with delta connection, and the control unit 31, which will be described later, acquires the measured voltages for three phases (hereinafter referred to as measurement results). The voltages applied to the primary windings 211, 221, and 231 are detected. These voltages may be detected by connecting three measuring transformers in a Δ connection, or may be detected using means such as resistive voltage division.

The tap changer 3 includes eight changeover switches ThA_U, ThB_U, ThC_U, ThD_U, Th1_U, Th2_U, Th3_U, Th4_U for switching the taps t1 to t4 of the secondary winding 212 of the regulating transformer 2, and a secondary winding. Eight changeover switches ThA_V, ThB_V, ThC_V, ThD_V, Th1_V, Th2_V, Th3_V, Th4_V for switching the taps t1 to t4 of the secondary winding 232 and eight changeover switches ThA_W for switching the taps t1 to t4 of the secondary winding 232. , ThB_W, ThC_W, ThD_W, Th1_W, Th2_W, Th3_W, and Th4_W.

The configuration of the tap changer 3 is not limited to that shown in FIG. 1, and may include, for example, a tap selection switch for changing the polarity that changes the polarity of the voltage applied to the series transformer 1.

The tap changer 3 further includes a control section 31 that controls switching of each of the changeover switches, and a drive section 32 that turns on each changeover switch based on a drive signal from the control section 31. The control unit 31 is connected to secondary windings of measurement transformers PT1 and PT2, and secondary windings of measurement transformers PT3, PT4, and PT5 (corresponding to second measurement transformers) to be described later. There is. Connections between the control section 31 and each measurement transformer, and connections between the drive section 32 and each changeover switch are omitted from illustration.

The control unit 31 includes a CPU (Central Processing Unit) (not shown), and controls voltage adjustment according to a control program stored in a ROM (Read Only Memory) in advance. Temporarily generated information is stored in RAM (Random Access Memory). The control unit 31 also includes an FPGA (Field Programmable Gate Array) (not shown), obtains measurement results from the measurement transformers PT1 to PT5, and calculates the voltage according to the first embodiment.

The tap t1 of the secondary winding 212 is connected to one end of the changeover switches ThA_U and Th1_U via a protective fuse (not shown; the same applies hereinafter), and the tap t2 is connected to one end of the changeover switches ThB_U and Th2_U via a fuse. The tap t3 is connected to one end of the changeover switches ThC_U and Th3_U via a fuse, and the tap t4 is connected to one end of the changeover switches ThD_U and Th4_U. The other ends of the changeover switches ThA_U, ThB_U, ThC_U, and ThD_U are connected to a neutral point N. The other ends of the changeover switches Th1_U, Th2_U, Th3_U, and Th4_U are connected to terminals u2 and v1 on the primary side of the series transformer 1 via a connection line 3u. The connection line 3u outputs an alternating current voltage corresponding to the U phase from the tap changer 3, and its phase is expressed as OU.

Tap t1 of the secondary winding 222 is connected to one end of changeover switches ThA_V and Th1_V via a fuse, tap t2 is connected to one end of changeover switches ThB_V and Th2_V via a fuse, and tap t3 is connected to one end of changeover switches ThA_V and Th2_V via a fuse. The tap t4 is connected to one end of the changeover switches ThD_V and Th4_V. The other ends of the changeover switches ThA_V, ThB_V, ThC_V, and ThD_V are connected to a neutral point N. The other ends of the changeover switches Th1_V, Th2_V, Th3_V, and Th4_V are connected to terminals v2 and w1 on the primary side of the series transformer 1 via a connection line 3v. The connection line 3v outputs an alternating current voltage corresponding to the V phase from the tap changer 3, and its phase is expressed as OV.

The tap t1 of the secondary winding 232 is connected to one end of the changeover switches ThA_W and Th1_W via a fuse, the tap t2 is connected to one end of the changeover switches ThB_W and Th2_W via a fuse, and the tap t3 is connected to one end of the changeover switches ThA_W and Th1_W via a fuse. The tap t4 is connected to one end of the changeover switches ThD_W and Th4_W. The other ends of the changeover switches ThA_W, ThB_W, ThC_W, and ThD_W are connected to a neutral point N. The other ends of the changeover switches Th1_W, Th2_W, Th3_W, and Th4_W are connected to terminals w2 and u1 on the primary side of the series transformer 1 via a connection line 3w. The connection line 3w outputs an alternating current voltage corresponding to the W phase from the tap changer 3, and its phase is expressed as OW.

A series circuit of a current limiting resistor R_UV and a bridge switch ThS_UV, and an electromagnetic contactor MC_UV are connected in parallel between the connection lines 3u and 3v. A series circuit of a current limiting resistor R_VW and a bridge switch ThS_VW, and an electromagnetic contactor MC_VW are connected in parallel between the connection lines 3v and 3w.

The bridge switch ThS_UV is a current limiting resistor between the taps in order to bridge the taps via the current limiting resistor R_UV in the process of switching the taps t1 to t4 of the secondary winding 212 or 222. This is for connecting and disconnecting the device R_UV. The bridge switch ThS_VW is a current limiting resistor between the taps in order to bridge the taps via the current limiting resistor R_VW in the process of switching the taps t1 to t4 of the secondary winding 222 or 232. This is for connecting and disconnecting the device R_VW. The electromagnetic contactors MC_UV and MC_VW connect terminals u1 and u2 on the primary side of the series transformer 1 when an overcurrent is detected and all the changeover switches are turned off, or when the operation of the tap changer 3 is stopped. This is to bridge between the terminals v1 and v2 and between the terminals w1 and w2 to prevent them from being in an open state.

In order to measure the voltage of the secondary windings 212, 222, 232 output from the switched taps, measuring transformers PT3, PT4, PT5 are connected between the connecting lines 3u, 3v, 3w. There is. That is, the primary winding of the measuring transformer PT3 is connected between the connecting wires 3u and 3v, and the primary winding of the measuring transformer PT4 is connected between the connecting wires 3v and 3w. A primary winding of a measuring transformer PT5 is connected between the connecting wires 3w and 3u. The secondary windings of the measurement transformers PT3, PT4, and PT5 are Y-connected and connected to the control unit 31. The control unit 31 acquires the measurement results for the three phases OU, OV, and OW from the secondary windings of the measurement transformers PT3, PT4, and PT5, thereby controlling the tap-switched secondary windings 212, 222, and 232. Voltage is detected.

Next, the configuration of each switch will be explained using the changeover switch ThA_U as an example. The same applies to other changeover switches and correction switches. FIG. 2 is a circuit diagram showing a configuration example of the changeover switch ThA_U. The changeover switch ThA_U is formed by connecting thyristors ThAa_U and ThAb_U in antiparallel, which conduct in one direction from the anode to the cathode. The anode of thyristor ThAa_U and the cathode of thyristor ThAb_U are connected to neutral point N. The cathode of thyristor ThAa_U and the anode of thyristor ThAb_U are connected to tap t1 of secondary winding 212 of regulating transformer 2. The gates of the thyristors ThAa_U and ThAb_U are connected to the drive section 32. When a trigger signal is applied from the drive unit 32 to the gate of each thyristor, the changeover switch ThA_U becomes bidirectionally conductive. The changeover switch ThA_U may be configured with one triac.

Next, combinations of changeover switches to be turned on will be explained. FIG. 3 is a chart showing the relationship between the tap position and the switch to be turned on for the OU phase. Similar charts are shown for the other OV and OW phases, with U read as V and W. In the following, explanation will be given mainly using the OU phase as an example, but the same explanation can be applied to the OV phase and the OW phase.

There are 13 combinations of changeover switches, and these combinations are represented by tap positions from tap 1 to tap 13. For example, when the tap position is set to tap 1, the changeover switches ThD_U and Th1_U are turned on. Thereby, the tap t1 of the secondary winding 212 is connected to the connection line 3u, and the tap t4 is connected to the neutral point N. In this case, the number of turns between taps t1 and t4 becomes equal to the number of turns of secondary winding 212, and the magnitude of the phase voltage of the OU phase becomes maximum.

Regarding taps 2 to 6, the changeover switches that connect the two taps to the connection line 3u and the neutral point N are determined according to the combination of taps that reduces the number of turns between the taps to five stages. For example, when the tap position is set to tap 6, the changeover switches ThD_U and Th3_U are turned on. Thereby, the tap t3 of the secondary winding 212 is connected to the connection line 3u, and the tap t4 is connected to the neutral point N. In this case, the number of turns between taps t3 and t4 is the minimum except for 0, and the magnitude of the phase voltage of the OU phase is the minimum except for 0.

When the tap position is set to tap 7, the changeover switches ThD_U and Th4_U are turned on. Thereby, the tap t4 of the secondary winding 212 is connected to the connection line 3u, and the same tap t4 is connected to the neutral point N. In this case, the number of turns between taps t4 and t4 becomes 0, and the phase voltage of the OU phase becomes 0. This is a so-called transparent tap.

Regarding taps 8 to 12, the changeover switches that connect the two taps to the connection line 3u and the neutral point N are determined according to the combination of taps that increases the number of turns between the taps in five stages. For example, when the tap position is set to tap 8, the changeover switches ThC_U and Th4_U are turned on. Thereby, the tap t4 of the secondary winding 212 is connected to the connection line 3u, and the tap t3 is connected to the neutral point N. In this case, the number of turns between taps t3 and t4 is the minimum except for 0, and the magnitude of the phase voltage of the OU phase is the minimum except for 0. However, compared to the case of tap 6, the phase of the phase voltage of the OU phase is reversed.

When the tap position is set to tap 13, the changeover switches ThA_U and Th4_U are turned on. Thereby, the tap t4 of the secondary winding 212 is connected to the connection line 3u, and the tap t1 is connected to the neutral point N. In this case, the number of turns between taps t1 and t4 becomes equal to the number of turns of secondary winding 212, and the magnitude of the phase voltage of the OU phase becomes maximum. However, compared to the case of tap 1, the phase of the phase voltage of the OU phase is reversed.

As mentioned above, the number of turns between the two taps connected to the connection line 3u and the neutral point N by tap switching is determined depending on the tap position.In other words, the number of turns between the taps is determined depending on the tap position. The turns ratio of 2 is determined. The turns ratio referred to here is the ratio of the number of turns of the primary winding 211 to the number of turns between the two taps connected to the connection line 3u and the neutral point N by tap switching. Therefore, as shown in FIG. 3, the tap positions from tap 1 to tap 13 are associated with the turns ratios from NT_U1 to NT_U13. However, if the tap position is tap 7, it is impossible to calculate the turns ratio according to the above definition, so no correspondence is made between the tap position and the turns ratio. NT_U1 to NT_U13 are collectively referred to as NT_U.

In the first embodiment, a table in which the tap positions shown in FIG. 3 are associated with the switch to be turned on and the turn ratio is stored in advance in the ROM of the control unit 31. The control section refers to this table every time the tap position is raised or lowered, and reads out the information indicating the changeover switch to be turned on and the turns ratio, thereby easily performing the tap changeover process.

Next, as an example, the voltage added to or subtracted from the V-phase AC voltage from the power supply side will be explained. FIG. 4 is an explanatory diagram showing the relationship between the voltages of the power distribution lines 1u, 1v, and 1w and the voltage applied to the primary winding 121 of the series transformer 1. FIG. 4A shows the relationship between the voltage phases of the distribution lines 1u, 1v, and 1w and the voltage phases of the connection lines 3u, 3v, and 3w. FIG. 4B shows that the voltage applied to the primary winding 121 is combined based on the voltages of the connection lines 3u and 3v.

First, the voltages of the OU phase, OV phase, and OW phase in the connection lines 3u, 3v, and 3w will be explained with reference to FIG. 4A. When the U-phase, V-phase, and W-phase voltage vectors supplied from the power supply are shown by thick solid line arrows, the magnitudes of the U-phase, V-phase, and W-phase voltage vectors in the distribution lines 1u, 1v, and 1w, respectively, are as follows. Depending on the voltage step-up or step-down by the series transformer 1, the voltage vector becomes larger or smaller than the U-phase, V-phase, and W-phase voltage vectors. Here, it is illustrated assuming that the size is smaller. Voltages V_uv, V_vw, and V_wu between the phases uv, vw, and wu are applied to each of the primary windings 211, 221, and 231 of the regulating transformer 2, as shown by broken line arrows. Voltages in phase with the voltages V_uv, V_vw, and V_wu are induced in the secondary windings 212, 222, and 232 of the regulating transformer 2, respectively.

For example, when one of the changeover switches Th1_U, Th2_U, Th3_U, and Th4_U is turned on, one of the taps of the secondary winding 212 is connected to the connection line 3u, and one of the changeover switches ThA_U, ThB_U, ThC_U, and ThD_U is turned on. By turning on, any other tap is connected to the neutral point N. The same can be said about the secondary windings 222 and 232 of the regulating transformer 2 by replacing U with V and W.

As explained using FIG. 3, the phase voltage of the OU phase is The phases are opposite to each other. Here, a case where the tap position is any one of taps 1 to 6 will be described. In this case, the voltages of the OU phase, OV phase, and OW phase in each of the connection lines 3u, 3v, and 3w are in phase with the voltages V_uv, V_vw, and V_wu, as shown by thin solid line arrows in FIG. 4A. That is, the voltages of the OU phase, OV phase, and OW phase lead the voltages of the U phase, V phase, and W phase by 30 degrees in phase. On the other hand, VO_UV, which is the voltage between the OU phase and the OV phase, is applied to the primary winding 121 of the series transformer 1, as shown by the dashed-dotted arrow. In the following, it is assumed that the tap positions of the secondary windings 212, 222, and 232 are the same unless otherwise specified.

Returning to FIG. 1, attention is now paid to, for example, the primary winding 121 and the secondary winding 122 of the series transformer 1. As described above, between the terminals v1 and v2 of the primary winding 121, the voltage VO_UV is applied from the terminal v2 to v1. In this case, the voltage induced in the secondary winding 122 corresponding to the voltage VO_UV also becomes a voltage in phase with the voltage VO_UV. Therefore, a voltage proportional to the voltage VO_UV is added to the V-phase AC voltage from the power supply side and supplied to the load side.

On the other hand, the voltage VO_UV shown by the dashed-dotted arrow in FIG. 4A is a voltage in opposite phase to the V-phase voltage shown by the thick solid arrow. That is, since a voltage proportional to the voltage VO_UV having an opposite phase to the V-phase voltage is added to the V-phase AC voltage, a voltage having the same phase as the V-phase AC voltage is subtracted. In other words, the V-phase AC voltage from the power supply side is stepped down, and the V-phase AC voltage is supplied to the load side.

Next, with reference to FIG. 4B, it will be explained that the voltage applied to the primary winding 121 changes depending on the tap position. The voltages of the OU phase and the OV phase change in magnitude in 13 steps depending on the tap positions from tap 1 to tap 13, respectively. The voltages of the OU phase when the tap positions are from tap 1 to tap 13 are represented by OU_1 to OU_13. Similarly, the voltages of the OV phase when the tap positions are from tap 1 to tap 13 are represented by OV_1 to OV_13. The phase from voltage OU_1 to voltage OU_6 is in phase with the OU phase shown in FIG. 4A. The phase from voltage OU_8 to voltage OU_13 is opposite to the OU phase shown in FIG. 4A. It is assumed that the starting point of all the voltage vectors explained in FIG. 4B is at the base point BP shown in the center of the figure.

The voltage vector of the voltage VO_UV applied to the primary winding 121 is obtained by subtracting the OV phase voltage vector from the OU phase voltage vector in FIG. 4A. In other words, the voltage vector of the voltage VO_UV is the sum of the voltage vector of the OU phase and the inverse vector of the voltage vector of the OV phase. In order to visually show these additions in FIG. 4B, the direction of the voltage vector from voltage OV_1 to voltage OV_6 in FIG. 4B is reversed from that of the OV phase voltage in FIG. 4A. The direction of the voltage vector from voltage OV_8 to voltage OV_13 is made the same as the voltage of the OV phase in FIG. 4A.

For example, when the tap position is tap 3, a voltage vector obtained by vectorially adding voltage OU_3 and a voltage in the opposite direction of voltage OV_3 is represented by a thin solid arrow. This voltage vector applied from terminal v2 to v1 of primary winding 121 is in the opposite direction to the V-phase voltage vector represented by the thick solid arrow. That is, it was confirmed that when the tap position is tap 3, the voltage induced in the secondary winding 122 of the series transformer 1 causes the V-phase voltage from the power supply side to be stepped down.

When the tap positions are from tap 8 to tap 13, it is clear from FIG. 4B that the voltage vector applied to terminals v2 to v1 of the primary winding 121 has the same direction as the V-phase voltage vector. It is. In this case, the V-phase voltage from the power supply side is boosted. In this way, as the tap number of the tap position increases from 1 to 6, the absolute value of the voltage stepped down becomes smaller, and the voltage stepped down at tap 7 (throughput) becomes 0. Thereafter, as the tap number of the tap position is further increased, the V-phase AC voltage from the power supply side is sequentially stepped up and supplied to the load side.

In reality, there may be combinations in which the tap positions of the secondary windings 212, 222, and 232 differ, so the end point of the voltage vector applied from terminal v2 to v1 of the primary winding 121 is shown in the circle in FIG. 4B. This will be any of the 169 points indicated by marks (including cases where the voltage magnitude is 0). Therefore, for example, the v-phase voltage shown in FIG. 4A is not necessarily boosted or stepped down while remaining in the same phase as the V-phase voltage, and generally some phase difference occurs.

As described above, by switching the tap positions from tap 1 to tap 13, the U-phase, V-phase, and W-phase AC voltages from the power supply side are adjusted stepwise from the step-down voltage to the step-up voltage, and the U-phase , v-phase, and w-phase AC voltage. The control unit 31 detects the line voltages of the u-phase, v-phase, and w-phase using the measurement transformers PT1 and PT2, and when the detected voltage deviates from the dead zone, increases or decreases the u-phase by raising or lowering the tap position. Adjust the line voltages of phase, v phase, and w phase so that they approach the reference voltage. In the first embodiment, the tap positions are adjusted to be the same for each of the secondary windings 212, 222, and 232, but by independently switching each tap position, the U-phase, V-phase, and W-phase It is also possible to improve the imbalance of AC voltage.

When switching the tap position, the control unit 31 calculates voltages V_UV, V_VW, and V_WU, which are line voltages on the power supply side in the distribution lines 1u, 1v, and 1w, and compares the calculated voltages V_UV, V_VW, and V_WU with the line voltages on the load side. The target tap position is determined based on the difference between the line voltages V_uv, V_vw, and V_wu. The voltages V_uv, V_vw, and V_wu are detected by acquiring the measurement results of the measurement transformers PT1 and PT2. In the following, calculation of voltages V_UV, V_VW, and V_WU will be explained using calculation of voltage V_UV as an example.

FIG. 5 is an explanatory diagram showing the relationship between the voltages detected by the measurement transformers PT1 to PT5 and the voltages in the distribution lines 1u, 1v, and 1w. A method for calculating voltage V_UV will be explained using this diagram. The voltages V_VW and V_WU are calculated in the same way. Dashed arrows indicate detected or calculated voltages. Solid arrows indicate voltages obtained from each measurement transformer. The correspondence between the right side of the page and the left side of the page is shown by a solid line and a dashed-dotted line. A solid line extending in the horizontal direction of the paper indicates a one-to-one correspondence. A dashed-dotted line extending in the lateral direction of the paper indicates that the series transformer 1 is interposed therebetween.

First, the following symbols are defined. The symbols used to calculate voltages V_VW and V_WU are similarly defined.
V_U, V_V: Phase voltage on the power supply side in the distribution lines 1u, 1v V_UV: Line voltage on the power supply side in the distribution lines 1u, 1v V_u, V_v: Phase voltage on the load side in the distribution lines 1u, 1v V_uv: Distribution line 1u, Load-side line voltage V_1u at 1v: Voltage applied from terminal u1 to u2 of primary winding 111 of series transformer 1 V_1v: From terminal v1 to v2 of primary winding 121 of series transformer 1 Applied voltage V_2u: Voltage induced in the secondary winding 112 of series transformer 1 in phase with V_1u V_2v: Voltage induced in secondary winding 122 of series transformer 1 in phase with V_1v n1: Series transformer 1 Turns ratio V_uv': Measurement result of voltage V_uv by measuring transformer PT1 n2: Turns ratio VO_UV of measuring transformer PT1: Line voltage at connecting wires 3u and 3v (=-V_1v)
VO_WU: Line voltage at connection lines 3w and 3u (=-V_1u)
VO_UV': Measurement result of voltage VO_UV by measurement transformer PT3 VO_WU': Measurement result of voltage VO_WU by measurement transformer PT5 n3: Turns ratio of measurement transformers PT3 and PT5

Since the primary winding of the measuring transformer PT1 is connected between the distribution lines 1u and 1v, the voltage V_uv is detected using the voltage V_uv' which is the measurement result of the measuring transformer PT1. Similarly, since the primary winding of the measuring transformer PT2 is connected between the distribution lines 1v and 1w, the voltage V_vw is detected using the voltage V_vw' which is the measurement result of the measuring transformer PT2. Ru. Here, if the measurement result of the virtual measurement transformer connected between the distribution lines 1w and 1u is the voltage V_wu', the sum of the voltage vectors of the voltages V_uv', V_vw', and V_wu' becomes 0. Therefore, voltage V_wu' is calculated based on voltages V_uv' and V_vw', and voltage V_wu is calculated using voltage V_wu'.

Since the measuring transformer PT3 is connected between the connecting lines 3u and 3v from FIG. 1, the voltage VO_UV is detected using the voltage VO_UV' which is the measurement result of the measuring transformer PT3. This voltage VO_UV is the voltage applied from terminal v2 to v1 of the primary winding 121 of the series transformer 1, and is equal to the voltage V_1v applied from terminal v1 to v2, with the polarity reversed. Further, by dividing the voltage V_1v by the turns ratio n1 of the series transformer 1, the voltage V_2v induced in the secondary winding 122 is calculated.

In other words, the voltage V_2v is calculated by dividing the voltage VO_UV detected using the voltage VO_UV' which is the measurement result of the measurement transformer PT3 by (-n1). Similarly, the voltage V_2w is calculated by dividing the voltage VO_VW detected using the voltage VO_VW', which is the measurement result of the measurement transformer PT4, by (-n1). Further, the voltage V_2u is calculated by dividing the voltage VO_WU detected using the voltage VO_WU', which is the measurement result of the measurement transformer PT5, by (-n1).

V_UV, which is the line voltage on the power supply side, is expressed by the following equation (1) using the voltages V_U and V_V, and the voltages V_U and V_V are respectively expressed by the following equations (2) and (3).
V_UV=V_U-V_V・・・・・・・・・・・・・・・・・・(1)
V_U=V_u+V_2u・・・・・・・・・・・・・・・・・・・・・(2)
V_V=V_v+V_2v・・・・・・・・・・・・・・・・・・(3)

From equations (1) to (3), voltage V_UV is transformed as shown in equation (4) below. This equation (4) corresponds to the vector relationship of each voltage shown in FIG.
V_UV=(V_u-V_v)+(V-2u-V_2v)
=V_uv+(V-2u-V_2v)・・・・・・・・・・・・(4)

The voltage V_uv is expressed using the voltage V_uv' which is the measurement result by the measuring transformer PT1 and the turns ratio of the measuring transformer PT1, and the voltages V-2u and V_2v are connected in series with the voltages V-1u and V_1v, respectively. Since it is expressed using the turns ratio n1 of the transformer 1, equation (4) is transformed as shown in equation (5) below.
V_UV=V_uv'×n2+(V-1u-V_1v)/n1...(5)

Since voltages V-1u and V_1v in equation (5) are obtained by inverting the signs of voltages VO_WU and VO_UV as described above, equation (5) is transformed as shown in equation (6) below.
V_UV=V_uv'×n2+(VO_UV-VO_WU)/n1...(6)

Since the voltages VO_UV and VO_WU are expressed using the measurement results of the measurement transformers PT3 and PT5, VO_UV' and VO_WU, and the turns ratio of the measurement transformers PT3 and PT5, equation (6) is as follows. is transformed as shown in equation (7).
V_UV=V_uv'×n2+(VO_UV'-VO_WU')×n3/n1...(7)

Equation (7) indicates that the voltage V_UV, which is the line voltage on the power supply side, is calculated using the measurement results of the measurement transformers PT1, PT3, and PT5. Furthermore, if the formula (7) is configured so that n2=n3/n1, that is, the turns ratio n3 of the measuring transformers PT3 and PT5 is n3=n1×n2, then the formula (7) is transformed as shown in equation (8) below to simplify the calculation of voltage V_UV.
V_UV=(V_uv'+VO_UV'-VO_WU')×n2...(8)

Similarly, voltages V_VW and V_WU are expressed by the following equations (9) and (10), respectively. When the relationship of the turns ratio is n3=n1×n2, the voltages V_VW and V_WU are respectively expressed by the following equations (11) and (12).
V_VW=V_vw'×n2+(VO_VW'-VO_UV')×n3/n1...(9)
V_WU=V_wu'×n2+(VO_WU'-VO_VW')×n3/n1
・・・・・・(10)
V_VW=(V_vw'+VO_VW'-VO_UV')×n2...(11)
V_WU=(V_wu'+VO_WU'-VO_VW')×n2...(12)

Below, the operation of the control section 31 described above will be explained using a flowchart showing the operation. FIG. 6 is a flowchart showing the processing procedure of the control unit 31 that calculates the voltages V_UV, V_VW, and V_WU on the power supply side. This processing procedure is started at the cycle of monitoring the voltages of the power distribution lines 1u, 1v, and 1w, and is executed by the FPGA included in the control unit 31. The process in FIG. 6 may be executed by the CPU.

When the process of FIG. 6 is started, the FPGA acquires voltages V_uv' and V_vw' as measurement results from the measurement transformers PT1 and PT2 (S11: corresponds to the first acquisition unit). Next, the FPGA calculates voltage V_wu' as a virtual measurement result based on the acquired voltages V_uv' and V_vw' (S12).

After that, the FPGA acquires voltages VO_UV', VO_VW', and VO_WU' as measurement results from the measurement transformers PT3 to PT5 (S13: corresponds to a second acquisition unit). Next, the FPGA calculates the voltage V_UV on the power supply side by substituting the obtained voltage V_uv' and voltages VO_UV' and VO_WU' into the right side of equation (7) or (8) (S14: equivalent to the calculation unit). ).

After that, the FPGA calculates the voltage V_VW on the power supply side by substituting the obtained voltage V_vw' and voltages VO_VW' and VO_UV' into the right side of equation (9) or (11) (S15: corresponds to the calculation unit ). Furthermore, the FPGA calculates the voltage V_WU on the power supply side by substituting the calculated voltage V_wu' and the obtained voltages VO_WU' and VO_VW' into the right side of equation (10) or (12) (S16: calculation unit ), the process in FIG. 6 ends.

As described above, according to the first embodiment, the primary windings 111, 121, 131 of the series transformer 1 have the secondary windings 112, 122, 132 connected in series to the distribution lines 1u, 1v, 1w, respectively. On the other hand, the taps t1 to t4 of the secondary windings 212, 222, 232 of the on-load tap switching transformer 200 have the primary windings 211, 221, 231 connected in parallel between the distribution lines 1u, 1v, 1w. Adjustment voltage is applied from Based on the measurement results of the voltage on the load side of the connection position of the series transformer 1 in the distribution lines 1u, 1v, 1w and the measurement result of the voltage applied to the primary windings 111, 121, 131 of the series transformer 1. Since it becomes possible to calculate the voltage on the power supply side rather than the connection position, a measuring transformer for measuring the voltage on the power supply side becomes unnecessary.

Further, according to the first embodiment, for example, a voltage obtained by multiplying the voltage V_uv′, which is the measurement result of the voltage V_uv on the load side, by the turns ratio n2 of the measurement transformers PT1 and PT2 that measure the voltage, and the series transformer 1 The voltages VO_UV' and VO_WU', which are the measurement results of the voltages obtained by inverting the voltages V_1v and V_1u applied to the primary windings 121 and 111, respectively, are determined by the turns ratio n3 and series connection of the measuring transformers PT3 and PT5 that measure the voltages. In order to calculate the voltage on the power supply side from the above connection position based on the voltage multiplied by the reciprocal of the turns ratio n1 of transformer 1 (see formula (7)), each measurement result and the turns ratio of each transformer are Based on this, the voltage on the power supply side can be easily calculated.

Furthermore, according to the first embodiment, the value of the turns ratio n3 of the measuring transformers PT3 and PT5 that measures the voltage obtained by inverting the voltages V_1v and V_1u applied to the primary windings 121 and 111 of the series transformer 1, respectively, for example. By setting , to a value obtained by multiplying the turns ratio n2 of the measurement transformers PT1 and PT2 that measure the voltage on the load side by the reciprocal of the turns ratio n1 of the series transformer 1, each measurement result and the measurement transformer PT1 The voltage on the power supply side can be easily calculated based on the turns ratio n2 (see equation (8)).

Furthermore, according to the first embodiment, the voltage V_uv between the lines of the u phase and the v phase calculated from the voltage V_uv' which is the measurement result of the voltage V_uv on the load side, and the primary windings 111 and 121 of the series transformer 1, for example. The difference between the voltages V_2u and V_2v induced in the secondary windings 112 and 122 of the series transformer 1 calculated from the voltages VO_WU' and VO_UV', which are the measurement results of voltages obtained by inverting the voltages V_1u and V_1v applied to them, respectively. Based on this, the line voltage on the power supply side can be easily calculated (see equations (4) to (8)).

Note that in the first embodiment, the line voltage on the power supply side is calculated by detecting the line voltage on the load side, but the phase voltage on the power supply side is calculated by detecting or calculating the phase voltage on the load side. It is also possible to do so. For example, the U-phase voltage V_U on the power supply side is calculated by the following equation (13) using the load-side U-phase voltage V_u and the voltage V_2u induced in the secondary winding 112 of the series transformer 1. be able to. V_2u is calculated from -(VO_WU)/n1 with reference to equations (4) to (6).
V_U=V_u+V_2u・・・・・・・・・・・・・・・・・・(13)

Further, in the first embodiment, the voltage regulator 100 has the regulator transformer 2 in which the Δ-Y secondary windings 212, 222, 232 are Y-connected via the tap changer 3, and the series transformer Although the primary windings 111, 121, and 131 of the first embodiment are connected in a delta connection, the present invention is not limited to this. For example, in the case where the secondary windings 212, 222, 232 of the regulating transformer 2 are Δ-connected via the tap changer 3, and the primary windings 111, 121, 131 of the series transformer 1 are Y-connected. However, by Y-connecting the measuring transformers PT3, PT4, and PT5, the voltage on the power supply side can be calculated in exactly the same way. Specifically, for example, if the measurement results of the OU phase and OV phase by the measurement transformers PT3 and PT4 are the voltages VO_U' and VO_V', the voltage can be calculated by the following equation (14), which is a modification of the equation (7). V_UV is calculated.
V_UV=V_uv'×n2+(VO_U'-VO_V')×n3/n1...(14)

(Embodiment 2)
In the first embodiment, the voltage on the power supply side is detected and the voltage on the power supply side is calculated, whereas in the second embodiment, the voltage on the power supply side is detected and the voltage on the load side is calculated. . FIG. 7 is a block diagram showing a configuration example of the voltage regulator 100 according to the second embodiment. In the second embodiment, the connection points of the measurement transformers PT1 and PT2 from which the voltage regulator 100 obtains measurement results are different from the first embodiment.

Specifically, the primary winding of the measuring transformer PT1 is connected between the distribution lines 1u and 1v on the power supply side from the connection position of the series transformer 1 on the distribution lines 1u, 1v, and 1w. A primary winding of a measuring transformer PT2 is connected between electric wires 1v and 1w. Other parts corresponding to those in Embodiment 1 are given the same reference numerals and their explanations will be omitted.

V_uv, which is the line voltage on the load side, is expressed by the following equation (15) using the voltages V_u and V_v, and the voltages V_u and V_v are respectively expressed by the following equations (16) and (17).
V_uv=V_u-V_v・・・・・・・・・・・・・・・・・・(15)
V_u=V_U-V_2u・・・・・・・・・・・・・・・・・・(16)
V_v=V_V-V_2v・・・・・・・・・・・・・・・・・・(17)

From equations (15) to (17), voltage V_uv is transformed as shown in equation (18) below.
V_uv=(V_U-V_V)-(V-2u-V_2v)
=V_UV-(V-2u-V_2v)・・・・・・・・・・・・(18)

The voltage V_UV is expressed using the voltage V_UV' which is the measurement result by the measuring transformer PT1 and the turns ratio of the measuring transformer PT1, and the voltages V-2u and V_2v are connected in series with the voltages V-1u and V_1v, respectively. Since it is expressed using the turns ratio n1 of the transformer 1, similarly to the first embodiment, equation (18) is transformed as shown in equation (19) below.
V_uv=V_UV'×n2-(V-1u-V_1v)/n1
=V_UV'×n2-(VO_UV-VO_WU)/n1...(19)

Since the voltages VO_UV and VO_WU are expressed using the measurement results of the measurement transformers PT3 and PT5, VO_UV' and VO_WU, and the turns ratio of the measurement transformers PT3 and PT5, equation (19) is as follows. is transformed as shown in equation (20).
V_uv=V_UV'×n2-(VO_UV'-VO_WU')×n3/n1
・・・・・・(20)

Equation (20) indicates that the voltage V_uv, which is the line voltage on the load side, is calculated using the measurement results of the measurement transformers PT1, PT3, and PT5. Furthermore, if the equation (20) is configured so that n2=n3/n1, that is, the turns ratio n3 of the measuring transformers PT3 and PT5 is n3=n1×n2, then the equation (20) is transformed as shown in equation (21) below to simplify the calculation of voltage V_uv.
V_uv=(V_UV'-VO_UV'+VO_WU')×n2...(21)

Similarly, the voltages V_vw and V_wu are expressed by the following equations (22) and (23), respectively. When the turns ratio is in the relationship n3=n1×n2, the voltages V_vw and V_wu are expressed by the following equations (24) and (25), respectively.
V_vw=V_VW'×n2-(VO_VW'-VO_UV')×n3/n1
・・・・・・(22)
V_wu=V_WU'×n2-(VO_WU'-VO_VW')×n3/n1
...(23)
V_vw=(V_VW'-VO_VW'+VO_UV')×n2...(24)
V_wu=(V_WU'-VO_WU'+VO_VW')×n2...(25)

As described above, according to the second embodiment, the measurement result of the voltage on the power supply side from the connection position of the series transformer 1 in the distribution lines 1u, 1v, 1w, the primary windings 111, 121, Since it becomes possible to calculate the voltage on the load side from the connection position based on the measurement result of the voltage applied to 131, a measuring transformer for measuring the voltage on the load side becomes unnecessary.

The embodiments disclosed herein are illustrative in all respects and should not be considered restrictive. The scope of the present invention is indicated by the claims, not the above-mentioned meaning, and is intended to include meanings equivalent to the claims and all changes within the scope. Further, the technical features described in each embodiment can be combined with each other.

1u, 1v, 1w distribution line, 100 voltage regulator, 1 series transformer, 111, 121, 131 primary winding, 112, 122, 132 secondary winding, u1, u2, v1, v2, w1, w2 terminal, 200 on-load tap switching transformer, 2 regulating transformer, 211, 221, 231 primary winding, 212, 222, 232 secondary winding, t1, t2, t3, t4 tap, 3 tap switching device, 31 control section, 32 Drive section, Th1_U, Th2_U, Th3_U, Th4_U, ThA_U, ThB_U, ThC_U, ThD_U Changeover switch, 3u, 3v, 3w Connection line, ThS_UV, ThS_VW Straight switch, R_UV, R_VW Current limiting resistor, MC_UV, MC_VW electromagnetic Contactor, PT1, PT2, PT3, PT4, PT5 Measuring transformer

Claims (4)

A series transformer has a secondary winding connected in series to a distribution line that distributes three-phase AC voltage, and a primary winding is connected in parallel to the distribution line, and the taps of the secondary winding are switched. and an on-load tap-changing transformer connected to the primary winding of the series transformer, the voltage regulator comprising:
a first acquisition unit that acquires a measured voltage from a first measurement transformer that measures a voltage on one side of a connection position of the series transformer in the distribution line;
a second acquisition unit that acquires a measured voltage from a second measurement transformer that measures the voltage applied to the primary winding of the series transformer by the on-load tap change transformer;
a calculation unit that calculates the voltage on the other side of the connection position in the distribution line based on the measured voltage acquired by the first acquisition unit and the measured voltage acquired by the second acquisition unit ,
The calculation unit calculates a voltage obtained by multiplying the measured voltage acquired by the first acquisition unit by the turns ratio of the first measurement transformer, and a voltage obtained by multiplying the measured voltage acquired by the second acquisition unit by the second measurement transformer. The voltage on the other side is calculated based on the turns ratio of the transformer and the voltage multiplied by the reciprocal of the turns ratio of the series transformer.
Voltage regulator. A series transformer has a secondary winding connected in series to a distribution line that distributes three-phase AC voltage, and a primary winding is connected in parallel to the distribution line, and the taps of the secondary winding are switched. and an on-load tap-changing transformer connected to the primary winding of the series transformer, the voltage regulator comprising:
a first acquisition unit that acquires a measured voltage from a first measurement transformer that measures a voltage on one side of a connection position of the series transformer in the distribution line;
a second acquisition unit that acquires a measured voltage from a second measurement transformer that measures the voltage applied to the primary winding of the series transformer by the on-load tap change transformer;
a calculation unit that calculates the voltage on the other side of the connection position in the distribution line based on the measured voltage acquired by the first acquisition unit and the measured voltage acquired by the second acquisition unit ,
The second acquisition unit is connected to each of the three connection lines in the on-load tap change transformer.
Voltage regulator. The value of the turns ratio of the second measurement transformer is a value obtained by multiplying the turns ratio of the first measurement transformer by the turns ratio of the series transformer,
The calculation unit calculates the voltage of the other side based on a voltage obtained by multiplying each of the measurement voltage acquired by the first acquisition unit and the measurement voltage acquired by the second acquisition unit by the turns ratio of the first measurement transformer. The voltage regulator according to claim 1 or 2, wherein the voltage regulator is configured to calculate the voltage. The calculation unit is
Calculating the line voltage of one two-phase on the one side from the measured voltage acquired by the first acquisition unit,
Calculating the difference in voltage induced in the secondary windings of each of the two phases of the one from the measured voltages of each of the two phases of the one acquired by the second acquisition unit,
The voltage adjustment device according to claim 2 or 3, wherein the line voltage of the two phases on the other side is calculated based on the calculated line voltage and the calculated difference.

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