JP2004235587A - Controller for on-load tap changing transformer and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller and a control method for an on-load tap changing transformer including a lock control circuit simplifying the structure of the lock control circuit, and surely preventing unnecessary operations of an on-load tap changer at the start of a motor for an auxiliary apparatus needing a heavy load and locking a control command of stepping up or down a tap given to the on-load tap changer. <P>SOLUTION: Provided is the controller of the on-load tap changer transformer, which is provided with: a current transformer 15 that is placed in a system for tying the on-load tap changer transformer and a heavy load; and a current comparison judging section 24 for comparing a current detected by the current transformer with a current within a preset current range, and the current comparison judging section 24 judging that the heavy load is started when the detected current is within the preset current range and stopping the control of a tap position of the on-load tap changing transformer independently of a result of comparison of voltages by an automatic voltage adjuster. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an on-load tap-changing transformer in a power plant or the like, and particularly to a control of an on-load tap-changing transformer that prevents unnecessary operation of the on-load tap-changing device when starting or stopping a large auxiliary machine in the plant. The present invention relates to an apparatus and a control method thereof.
[0002]
[Prior art]
In recent power transformers, there are many on-load tap-switching transformers which are provided with a tap-on-load switch and adjust the output voltage while a load is applied.
[0003]
As shown in FIG. 9, the on-load tap-switching transformer converts power supplied from, for example, a power supply equipment (power system) 11 of a power company into a transformer 1, a on-load tap-switch 2, a power receiving circuit breaker 7, and the like. , An in-house bus 8, a circuit breaker 9, a large load, for example, a large auxiliary motor 10 and the like.
[0004]
The on-load tap change transformer detects the voltage of the bus 8 in the station by the instrument transformer 4, calculates based on the detected voltage, and outputs a calculation signal to the on-load tap changer 2 as a control command. A switch control device 3 is provided.
[0005]
This tap changer control device 3 calculates the difference when the voltage of the bus 8 in the station has a deviation from a predetermined voltage, and raises the tap of the on-load tap changer 2 by the operation signal. Alternatively, an automatic voltage regulator 5 for issuing a tap lowering control command and an abnormal voltage detector 6 for detecting that the voltage of the in-house bus 8 has deviated from a prescribed voltage are provided.
[0006]
The on-load tap change transformer having such a configuration is executed based on the flowchart shown in FIG. 10 when the on-load tap changer 2 performs tap-up or tap-down operation.
[0007]
The on-load tap change transformer first checks whether or not to use the on-load tap changer 2. If not, the tap change transformer is excluded (no control is performed) (step 2). Among the on-load tap changers 2 provided in each of the transformers arranged in the above, the on-load tap changer 2, which is a lock target of the tap-up or tap-down control command when the large auxiliary machine is started, is used. (Step 1), and the tap changer control device 3 starts the lock control of the tap-up or tap-down of the load tap changer 2 (Step 3).
[0008]
Next, in response to the tap-up / tap-down control command, the on-load tap-switching transformer determines whether or not the target device whose control is to be locked has been activated (step 4). This determination is based on the opening or closing of the load circuit breaker 9 connected between the in-house bus 8 and the target device. When the load circuit breaker 9 is closed, the auxiliary motor is activated, When the load breaker 9 is open, it is determined that the auxiliary motor is stopped. Regarding the determination of the start of the load, when there are a plurality of loads (buses) to be controlled, the operated load (bus) is added to the information of the contact of the power receiving circuit breaker connected between the transformer and the bus. There is one that determines which load (bus) is operating on the basis of this (Patent Document 1).
[0009]
On the other hand, the secondary voltages detected by the instrument transformer 4 from the in-house bus are used for control and alarm, respectively (steps 6 and 9). It is determined whether the secondary voltage input for control is higher than the dead zone of the automatic voltage regulator 5 and equal to or higher than the upper limit value, or lower than the dead zone and equal to or lower than the lower limit value (step 7). When the secondary voltage is equal to or more than the upper limit value or equal to or less than the lower limit value than the dead zone, an AND condition (a first AND signal) is set between the secondary voltage and a signal indicating that the device to be locked by tap control is stopped.
[0010]
At the same time, it is determined whether the secondary voltage (step 9) input for alarm is an abnormal voltage (step 10). If the voltage is abnormal, an AND condition (a second AND signal) is set between the signal and a signal indicating that the device to be locked by tap control is stopped. It is determined whether or not the LTC is locked based on the input of the second AND signal. If the LTC is locked, an abnormal alarm is output (step 11). Further, when the LTC is not locked, an AND condition is further taken between the LTC and the first AND signal, and when both are completed, the LTC is operated, that is, the operation of raising or lowering the tap is performed. (Step 8).
[0011]
The on-load tap-changing transformer that executes such a flow chart is a tap of the on-load tap-changer 2 for a certain period of time from a voltage drop occurring when the auxiliary motor 10 is started to a predetermined specified voltage return. From the viewpoint of preventing chattering due to the raising or lowering operation and suppressing the unnecessary operation, the tap-up or lowering control command given from the tap-changer control device 3 to the on-load tap changer 2 is locked.
[0012]
When the voltage drop due to the activation of the auxiliary motor 10 returns to the specified voltage and the lock of the tap-up or tap-down control command is released, the on-load tap switching transformer enters a normal operation.
[0013]
During normal operation, when the voltage detected from the in-house bus 8 is lower than the voltage obtained by adding the dead zone of the automatic voltage regulator 5 to the specified voltage, for example, the tap changer control device 3 sets the tap changer under load. In step 2, a control command for increasing the voltage, for example, increasing the tap by one tap is issued.
[0014]
Further, when the voltage detected from the in-house bus 8 is higher than the voltage obtained by adding the dead band to the specified voltage, the tap changer control device 3 sends a control command to lower the load tap changer 2 by, for example, one tap. Is out.
[0015]
The tap-up or tap-down operation of the on-load tap changer 2 is performed based on, for example, a time limit characteristic diagram shown in FIG. 11 incorporated in the automatic voltage regulator 5.
[0016]
When the actual voltage from the in-station bus 8 indicated by the broken line is lower than a value obtained by adding the dead zone to the specified voltage, the anti-time limit characteristic diagram indicates that the time limit crosses the anti-time limit curve L that defines the tap-down operation region. Is obtained by multiplying the product of the time ΔT and the deviation voltage ΔV of the above, and the control signal of, for example, lowering the tap by one tap from the automatic voltage regulator 5 of the tap changer controller 3 to the on-load tap changer 2 by the operation signal. It has become.
[0017]
[Patent Document 1]
JP 2002-23864 A
[0018]
[Problems to be solved by the invention]
Conventionally, the load tap change transformer has a transient, but fluctuating voltage from a drop to a specified value when the auxiliary motor 10 is started, which is a large load. 3, a tap-up or tap-down control command was repeatedly issued to the on-load tap changer 2. For this reason, the on-load tap changer 2 must operate every time a tap-up or tap-down control command is issued, even when the auxiliary machine electric motor 10 is started, which is an unnecessary operation. From the viewpoint of preventing this unnecessary operation, as shown in FIG. 11, one automatic time limit curve L is incorporated in the automatic voltage adjusting device 5 of the tap changer control device 3 to start the auxiliary electric motor 10 when starting. During a transition from a voltage drop to a specified voltage return, the tap control command from the tap changer control device 3 to the on-load tap changer 2 is locked.
[0019]
In addition, the lock condition is that the load breaker 9 is ON.
[0020]
However, if such a lock condition is set, the load tap change transformer may increase the capacity of the auxiliary motor 10 or add auxiliary motors or the like in parallel. It is no longer possible to lock a tap-up or tap-down control command at the time of starting new accessories by only the conventional lock condition, which has led to complication of incorporating a new control circuit.
[0021]
For example, as shown in FIG. 12, when rescue power is supplied from the A-unit of one electrical facility to the B-unit via the breakers 13 and 13, the B-unit has the lock condition other than its own. The lock condition of the A-unit had to be incorporated, and there was a problem that the control circuit was further complicated.
[0022]
As described above, the conventional load tap switching transformer requires additional auxiliary equipment in the future, parallel addition of new auxiliary equipment, supply of power to other equipment, etc., when starting auxiliary equipment. There is a need for a more simplified lock control circuit for locking a tap-up or tap-down control command.
[0023]
The present invention has been made in view of such circumstances, and when starting a large-load auxiliary motor or the like, reliably prevents unnecessary operation of a load tap changer, Control device for tap change transformer at load and its control, which simplifies the lock control circuit that locks the control command for tap-up or tap-down at start-up even if there is an increase in the capacity of a motor for motor use or additional installation, etc. The aim is to provide a method.
[0024]
[Means for Solving the Problems]
In order to achieve the above object, a control apparatus for a tap change transformer at load according to the present invention, as described in claim 1, is a transformer connected to a power grid via a transformer. A large load connected via a circuit breaker to the secondary side of the on-load tap-changing transformer, and an instrument transformer for detecting a voltage change in a bus in the station caused by starting and stopping of the large load. An automatic voltage regulator that compares a detected voltage from the instrument transformer with a predetermined set voltage; and a tap of the on-load tap switching transformer based on a comparison result of voltage values in the automatic voltage regulator. In the control device of the on-load tap-changing transformer for controlling the position, a current transformer is provided in a system connecting the on-load tap-changing transformer and the large load, and a current value detected by the current transformer is determined in advance. Set current range And a current comparison / determination unit for comparing with the automatic voltage regulator when the detected current value is within the range and determines that the large load is being started. The control of the tap position of the on-load tap change transformer is stopped regardless of the comparison result of the voltage values.
[0025]
In addition, in order to achieve the above object, the control device of the on-load tap switching transformer according to the present invention, as described in claim 2, wherein the current comparison determination unit includes an upper limit sudden change allowable current value and a lower limit. The current range determined by the sudden change allowable current value is stored, and the current range is compared with the current value detected by the current transformer, and when the current range is within the range, the large load is being started. Is determined.
[0026]
In addition, in order to achieve the above object, a control device for a tap changer at load according to the present invention, as set forth in claim 3, is a tap changer at load connected to a power system via a transformer. A transformer, a large load connected via a circuit breaker to the secondary side of the on-load tap-changing transformer, and an instrument transformer for detecting a voltage change in a bus in the station caused by starting and stopping of the large load. , An automatic voltage regulator for comparing a detected voltage from the instrument transformer with a predetermined set voltage, and the on-load tap switching transformer based on a comparison result of voltage values in the automatic voltage regulator. In the control device of the on-load tap-changing transformer for controlling the tap position, a current transformer is provided in a system connecting the on-load tap-changing transformer and the large load, and the reactive power detected by the current transformer is provided. Preset value A reactive power comparison and determination unit for comparing with the reactive power value range, and the reactive power comparison and determination unit determines that the large load is being activated when the detected reactive power value is within the range. The control of the tap position of the on-load tap change transformer is stopped regardless of the comparison result of the voltage values in the automatic voltage regulator.
[0027]
Further, in order to achieve the above object, the control apparatus for a tap change transformer at load according to the present invention, as set forth in claim 4, wherein the reactive power comparison and determination unit includes an upper limit sudden change allowable reactive power value. And stores a power value range defined by the lower limit sudden change allowable reactive power value, and performs a comparison operation between the power value range and the reactive power value detected by the current transformer. It is characterized in that it is configured to determine that a large load is being started.
[0028]
In addition, in order to achieve the above object, a control apparatus for a tap switching transformer at load according to the present invention, as set forth in claim 5, is configured to switch a tap at load connected to a power system via a transformer. A transformer, a large load connected via a circuit breaker to the secondary side of the on-load tap-changing transformer, and an instrument transformer for detecting a voltage change in a bus in the station caused by starting and stopping of the large load. , An automatic voltage regulator for comparing a detected voltage from the instrument transformer with a predetermined set voltage, and the on-load tap switching transformer based on a comparison result of voltage values in the automatic voltage regulator. In the control device of the tap change transformer at load for controlling the tap position of the load, a current transformer is provided in a system connecting the transformer at load change and the large load, and a power factor detected by the current transformer is provided. The preset force A power factor comparison / judgment unit for comparing with the range is provided. When the detected power factor is within the range, the power factor comparison / judgment unit judges that the large load is being started, and the automatic voltage It is characterized in that the control of the tap position of the on-load tap switching transformer is stopped irrespective of the comparison result of the voltage values in the adjusting device.
[0029]
In order to achieve the above object, the control device of the on-load tap-changing transformer according to the present invention, as set forth in claim 6, wherein the power factor comparison determination unit includes an upper limit sudden change allowable power factor and a lower limit conflict power factor. The power factor range determined by the variable allowable power factor is stored, and the power factor range is compared with the power factor detected by the current transformer. When the power factor range is within the range, the large load is activated. It is characterized in that it is configured to determine that it is inside.
[0030]
Further, in order to achieve the above object, the on-load tap switching transformer according to the present invention is configured such that the automatic voltage regulator has at least two or more anti-time limit curves. It has a time limit characteristic line.
[0031]
Further, in order to achieve the above object, the on-load tap switching transformer according to the present invention, as described in claim 8, has an anti-time limit characteristic line having at least two or more anti-time curves. It is characterized by being on the voltage drop side with respect to the voltage.
[0032]
Furthermore, in order to achieve the above object, the control method of the on-load tap-changing transformer according to the present invention is configured such that the primary side is connected to the power system via the transformer as described in claim 9. The tap position of the on-load tap change transformer whose secondary side is connected to a large load via a circuit breaker is preset in the voltage value from the instrument transformer provided on the bus in the station and in the automatic voltage regulator. Detecting a change in current value in a bus within the station when the large load is started or stopped, and A step of determining whether the current value is within a range between an upper limit sudden change allowable current value and a lower limit sudden change allowable current value set in a current comparison determination unit, and if the current value is within the range, the automatic voltage adjustment is performed. Comparison of voltage values within the device Those characterized by a step of stopping the control of the tap position regardless.
[0033]
In addition, in order to achieve the above object, the control method of the on-load tap change transformer according to the present invention is configured such that the primary side is connected to the power system via the transformer as described in claim 10. The tap position of the on-load tap change transformer whose secondary side is connected to a large load via a circuit breaker is preset in the voltage value from the instrument transformer provided on the bus in the station and in the automatic voltage regulator. Detecting a change in the reactive power value in the local bus when the large load is started or stopped, and Determining whether or not the reactive power value is within a range between an upper limit sudden change allowable reactive power value and a lower limit sudden change allowable reactive power value set in advance in the reactive power comparison determination unit; and The automatic voltage regulator Those characterized by a step of stopping the control of the tap position irrespective of the comparison result of the voltage value at the inner.
[0034]
Further, in order to achieve the above object, the control method of the on-load tap switching transformer according to the present invention is configured such that the primary side is connected to the power system via the transformer as described in claim 11. The tap position of the on-load tap change transformer whose secondary side is connected to a large load via a circuit breaker is preset in the voltage value from the instrument transformer provided on the bus in the station and in the automatic voltage regulator. Detecting a change in the power factor in the local bus when the large load is started or stopped, and A step of determining whether the power factor is within a range between an upper limit sudden change allowable power factor value and a lower limit change allowable power factor value set in advance in the power factor comparison and determination unit, and Comparison results of voltage values in the automatic voltage regulator Those characterized by a step of stopping the control of the tap position regardless.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a control device and a control method of a load tap switching transformer according to the present invention will be described with reference to the drawings and reference numerals attached to the drawings.
[0036]
FIG. 1 is a schematic system diagram showing a first embodiment of a control device and a control method for a load tap switching transformer according to the present invention.
[0037]
The on-load tap-switching transformer according to the present embodiment, for example, converts a voltage supplied from a power supply facility (power system) 12 of a power company into a transformer 13, a on-load tap switch 14, a current transformer 15, a power receiving circuit breaker. 16, an in-house bus 17, a load breaker 18, and a load, for example, an auxiliary motor 19 which is a large load.
[0038]
The on-load tap-changing transformer detects the voltage of the in-house bus 17 with the instrument transformer 20, calculates based on the detected voltage, and outputs the calculated signal to the on-load tap changer 14 by tapping up or down. Is provided as a tap changer control device 21 for issuing as a control command.
[0039]
The tap changer control device 21 calculates a difference between the voltage of the bus 17 in the office and a predetermined specified voltage, calculates the difference, and raises the tap of the on-load tap changer 14 based on the calculated signal. Alternatively, an automatic voltage adjuster 22 for issuing a tap lowering control command and an abnormal voltage detector 23 for detecting that the voltage of the in-house bus 17 has deviated from a prescribed voltage are provided.
[0040]
Further, the tap changer control device 21 detects the current on the secondary side of the on-load tap change transformer with the current transformer 15, compares the detected current value with a predetermined specified current value, and generates a deviation. And a current comparison / judgment unit 24 that locks a calculation signal for calculating the deviation and issuing a tap-up or tap-down control command from the automatic voltage regulator 22 to the on-load tap changer 14.
[0041]
The on-load tap change transformer having such a configuration is executed based on the flowchart shown in FIG. 2 when the on-load tap changer 14 performs tap-up or tap-down operation.
[0042]
The on-load tap-switching transformer first checks whether the on-load tap-switcher 14 operates, and if it operates, on-load tap switching provided in each of the plurality of transformers arranged in parallel. When the auxiliary equipment is activated, the on-load tap changer 14 is selected to lock the tap-up or tap-down control command when the auxiliary machine is started (step 1). The lock control for lowering is started by the tap changer control device 21 (step 2).
[0043]
Next, the on-load tap change transformer determines whether the accessory electric motor 19 to be locked in response to the tap-up or tap-down control command is activated or stopped ( Step 3). This determination is performed by the current comparison determination unit 24 of the tap changer control device 21. That is, the detection is performed based on the amount of change in current when the auxiliary motor 19 detected by the current transformer 15 starts. Specifically, the current value after the auxiliary motor 19 is started is determined in advance as a specified current value, and an allowable upper-limit current value and an allowable lower-limit current value are further determined for this current value. Then, when the amount of current change detected by the current transformer 15 falls between the upper limit current value and the lower limit current value, it is determined that the auxiliary machine motor 19 has started. A more detailed determination method of the current comparison determination unit 21 will be described later.
[0044]
When it is determined in step 3 that the auxiliary machine motor 19 has been activated, the automatic voltage regulator 22 stops tap-up and tap-down control.
[0045]
When the tap-up or tap-down control command is not locked, the automatic voltage adjuster 22 increases or decreases the dead band of the voltage of the bus 17 detected from the instrument transformer 20 to the specified voltage, as in the related art. If the value fluctuates as compared with the value, a tap-up or tap-down control command is calculated based on the deviation.
[0046]
When it is determined in step 3 that the auxiliary motor 19 is stopped, the signal of "the auxiliary motor 19 is stopped" and the instrument transformer 20 on the bus 17 which is the secondary side of the transformer 13 are output. An "abnormal alarm" is issued on condition that the "secondary abnormal voltage" signal from the voltage monitoring signal of "1" is completed.
[0047]
Here, when the auxiliary electric motor 19 is started, the current comparison / judgment unit 24 that locks the tap-up or tap-down control command to the on-load tap changer 14 calculated by the automatic voltage regulator 22 includes, for example, FIG. 3 is incorporated.
[0048]
This current fluctuation characteristic diagram shows the current I flowing on the secondary side of the on-load tap change transformer. ₁ Is the reference current, when the auxiliary motor 19 starts, the reference current I ₁ Suddenly changes and the reference current I ₁ In addition, the excess current ΔI flows.
[0049]
In this case, the current comparison determination unit 24 determines that the reference current I ₁ To the upper limit allowable current (error) ΔI _A Upper limit allowable sudden change current (I ₁ + ΔI _A ) Is the comparison current value A, and the reference current I ₁ Lower limit allowable fluctuation current (error) ΔI _B To which the lower limit allowable sudden change current (I ₁ + ΔI _B ) Is the comparison current value B and the reference current I ₁ To the actual sudden change current (I ₁ + ΔI) is the upper limit allowable sudden change current (I ₁ + ΔI _A ) To the lower limit allowable sudden change current (I ₁ + ΔI _B ) Is determined, and when the current is within the range of the comparison current value A and the comparison current value B, the tap is output from the automatic voltage regulator 22 to the load tap changer 14; Alternatively, the control command for tapping down is locked.
[0050]
As described above, in the present embodiment, the current transformer 15 is provided on the secondary side of the on-load tap switching transformer, and the current at the time of starting the auxiliary machine motor 19 is detected by the current transformer 15, and the detected current Is a predetermined upper limit allowable sudden change current (I ₁ + ΔI _A ) To the lower limit allowable sudden change current (I ₁ + ΔI _B ) Is determined by the current comparison / determination unit 24. When the current value falls within the range, the tap-up or tap-down control command calculated by the automatic voltage regulator 22 is locked. Even if the capacity of the auxiliary motor 19 is increased or additionally installed, unlike the conventional case, it is not necessary to largely modify the lock circuit based on the circuit breaker ON condition, and a simple structure is provided. The control command for tapping up or tapping down can be easily locked while the load tap changer 14 is not operated unnecessarily at the time of starting the auxiliary motor 19.
[0051]
FIG. 4 is a schematic system diagram showing a second embodiment of the control device and the control method of the on-load tap switching transformer according to the present invention.
[0052]
The same components as those of the first embodiment are denoted by the same reference numerals.
[0053]
The on-load tap-changing transformer according to the present embodiment is configured such that the current transformer 15 detects a current flowing when the auxiliary motor 19 is started, and a reactive power generated from the detected current is a predetermined specified reactive power. The value is compared with the value, and when a deviation is found, the deviation is calculated, and a reactive power comparison judgment for locking a calculation signal for issuing a tap-up or tap-down control command from the automatic voltage regulator 22 to the on-load tap changer 14. The unit 25 is provided in the tap changer control device 21.
[0054]
Note that the other configuration is the same as the configuration shown in the first embodiment, and the description thereof will not be repeated.
[0055]
The reactive power comparison and determination unit 25 incorporates, for example, a reactive power fluctuation characteristic diagram shown in FIG.
[0056]
When the reactive power generated from the current flowing through the secondary side to the transformer is used as the reference reactive power Q, the reference reactive power Q suddenly changes when the auxiliary motor 19 starts. This shows that the excess reactive power ΔQ has been added to the reference reactive power Q.
[0057]
In this case, the reactive power comparison determination unit 25 sets the reference reactive power Q _A Upper limit allowable sudden change reactive power (Q + ΔQ _A ) Is the comparative reactive power A zone, and the lower limit allowable fluctuation reactive power (error) ΔQ is added to the reference reactive power Q. _B Lower limit allowable sudden change reactive power (Q + ΔQ _B ) Is the comparison reactive power B, and the actual reactive power (Q + ΔQ) obtained by adding the excess reactive power ΔQ to the reference reactive power Q is the upper limit allowable reactive power (Q + ΔQ). _A ) And lower limit allowable sudden change reactive power (Q + ΔQ) _B ), The tap output from the automatic voltage regulator 22 to the on-load tap changer 14 when the power falls within the range from the comparative reactive power A to the comparative reactive power B. The control command for raising or lowering the tap is locked.
[0058]
As described above, in the present embodiment, the current transformer 15 is provided on the secondary side of the transformer, and the current at the time of starting the auxiliary machine motor 19 is detected by the current transformer 15, and the invalid current generated from the detected current is detected. The power is a predetermined upper limit allowable sudden change reactive power (Q + ΔQ _A ) To the lower limit allowable sudden change reactive power (Q + ΔQ) _B ) Is determined by the reactive power comparison / determination unit 25, and when the value falls within the range, the tap-up or tap-down control command calculated by the automatic voltage regulator 22 is locked. Even if the capacity of the auxiliary motor 19 is increased or additionally installed, unlike the conventional case, it is not necessary to remodel the lock circuit based on the ON condition of the circuit breaker every time, and the structure is simple. The control command for tapping up or tapping down can be easily locked as it is, so that the load tap switch 14 does not needlessly operate when the electric motor 19 for auxiliary equipment is started.
[0059]
FIG. 6 is a schematic system diagram showing a third embodiment of the control device and the control method of the on-load tap switching transformer according to the present invention.
[0060]
The same components as those of the first embodiment are denoted by the same reference numerals.
[0061]
The on-load tap-changing transformer according to the present embodiment is configured such that the current transformer 15 detects a current flowing when the auxiliary machine motor 19 is started, and a power factor calculated from the detected current is a predetermined specified force. Power factor comparison judgment for calculating the deviation, calculating the deviation, and issuing a control command for tapping up or tapping down from the automatic voltage regulator 22 to the tap changer 14 under load. The unit 26 is provided in the tap changer control device 21.
[0062]
Note that the other configuration is the same as the configuration shown in the first embodiment, and the description thereof will not be repeated.
[0063]
The power factor comparison determination unit 26 incorporates, for example, a power vector diagram shown in FIG.
[0064]
This power vector diagram shows that when the power factor generated from the current flowing through the secondary side to the transformer is the reference power factor θ, when the auxiliary motor 19 starts, the reference power factor θ changes suddenly, This shows that the applied power component Δθ has reached the reference power factor θ.
[0065]
In this case, the power factor comparison determination unit 26 sets the upper limit allowable variation power factor (error) Δθ to the reference power factor θ. _A Upper limit allowable inflection power factor (θ + Δθ) _A ) Is the comparison power factor A, and the lower limit allowable variation (error) power factor Δθ is added to the reference power factor θ. _B Lower limit allowable sudden power factor (θ + Δθ) _B ) Is the comparison power factor B, and the actual inflection power factor (θ + Δθ) obtained by adding the excess power factor Δθ to the reference power factor θ is the upper limit allowable inflection power factor (θ + Δθ). _A ) And lower limit allowable power factor (θ + Δθ) _B ) Is determined to be within the range between the comparative power factor A and the comparative power factor B, and the tap output from the automatic voltage regulator 22 to the on-load tap changer 14 is determined. The control command for raising or lowering the tap is locked.
[0066]
As described above, in the present embodiment, the current transformer 15 is provided on the secondary side of the transformer, the current at the time of starting the auxiliary machine motor 19 is detected by the current transformer 15, and the force generated from the detected current is detected. Rate is a predetermined upper limit allowable inflection power factor (θ ₁ + Δθ _A ) To the lower limit allowable power factor (θ ₁ + Δθ _B ) Is determined by the power factor comparison / determination unit 26, and when the power is within the range, the tap-up or tap-down control command calculated by the automatic voltage regulator 22 is locked. Even if the capacity of the auxiliary motor 19 is increased or additionally installed, unlike the conventional case, it is not necessary to remodel the lock circuit based on the ON condition of the circuit breaker every time, and the structure is simple. The control command for tapping up or tapping down can be easily locked as it is, so that the load tap switch 14 does not needlessly operate when the electric motor 19 for auxiliary equipment is started.
[0067]
FIG. 8 is a time limit characteristic diagram showing a time limit curve incorporated in the automatic voltage regulator 22 applied to the control device and the control method of the on-load tap switching transformer according to the present invention.
[0068]
In the present embodiment, in the case of a power drop at the time of starting from one conventional time limit curve L indicated by a broken line in a time limit characteristic diagram incorporated in the automatic voltage regulator 22, at least two or more multiple time limit curves are used. Time limit curve L ₁ , L ₂ It was made.
[0069]
The conventional time limit characteristic diagram has a single time limit curve L as shown in FIG. However, when the auxiliary motor 19 was started, the voltage V dropped below a value obtained by adding the dead zone of the automatic voltage regulator 22 to the specified voltage, but the drop was found to fluctuate. For this reason, if there is a fluctuation in the voltage drop, the tap-up or tap-down control command to the on-load tap changer 14 cannot be reliably locked, and the on-load tap changer 14 may be operated unnecessarily. Was.
[0070]
The present embodiment takes this point into consideration, and in the time limit characteristic diagram incorporated in the automatic voltage regulator 22, at least two or more time limit curves L on the voltage drop side with respect to the specified voltage. ₁ , L ₂ Is provided.
[0071]
Therefore, according to the present embodiment, when the auxiliary motor 19 is started, a plurality of reverse time limit curves L that can sufficiently cope with the voltage drop fluctuations. ₁ , L ₂ , The control command for tapping up or tapping down to the on-load tap changer 14 can be reliably locked, and the on-load tap changer 14 does not needlessly operate.
[0072]
【The invention's effect】
As described above, the control device and the control method of the on-load tap-switching transformer according to the present invention lock the tap-switching control command to the on-load tap-switcher when the auxiliary motor is started, Instead of the conventional method of calculating based on the conditions of ON and ON of the circuit breaker, any one of the methods of current change, reactive power, power factor change, and creation of a plurality of reverse time limit curves , The tap switching control command is locked, so that even if the capacity of the auxiliary motor is increased or additionally installed, the lock control circuit can be adequately dealt with without significantly modifying the lock control circuit.
[Brief description of the drawings]
FIG. 1 is a schematic system diagram showing a first embodiment of a control device and a control method of a load tap switching transformer according to the present invention.
FIG. 2 is a flowchart showing steps for causing a tap-on or load-down tap changer to apply a tap-up or tap-down operation applied to the control device and the control method of the on-load tap switching transformer according to the present invention.
FIG. 3 is a diagram illustrating a current fluctuation characteristic line incorporated in a current comparison / determination unit applied to the control device and the control method of the on-load tap switching transformer according to the present invention.
FIG. 4 is a schematic system diagram showing a second embodiment of a control device and a control method for a tap change transformer at load according to the present invention.
FIG. 5 is a diagram showing a reactive power characteristic line incorporated in a reactive power comparison / determination unit applied to the control device and the control method of the on-load tap switching transformer according to the present invention;
FIG. 6 is a schematic system diagram showing a third embodiment of the control device and the control method of the on-load tap switching transformer according to the present invention.
FIG. 7 is a diagram showing a power vector incorporated in a power factor comparison / determination unit applied to the control device and the control method of the on-load tap change transformer according to the present invention.
FIG. 8 is a diagram showing a time limit characteristic line incorporated in the control device of the on-load tap switching transformer and the automatic voltage regulator applied to the control method according to the present invention.
FIG. 9 is a schematic system diagram showing a conventional on-load tap switching transformer.
FIG. 10 is a flowchart showing steps of causing a load tap changer applied to a conventional load tap change transformer to perform tap-up or tap-down operation.
FIG. 11 is a diagram showing a time limit characteristic line incorporated in a conventional automatic voltage regulator applied to a load tap switching transformer.
FIG. 12 is a schematic system diagram showing another conventional on-load tap switching transformer.
[Explanation of symbols]
1 Transformer
2 Tap changer under load
3 Tap changer controller
4 Instrument transformer
5 Automatic voltage regulator
6 Abnormal voltage detector
7 Power receiving circuit breaker
8 In-house bus
9 Load breaker
10 Motor for auxiliary equipment
11,12 Power supply equipment (power system)
13 Transformer
14 Tap changer under load
15 Current transformer
16 Power receiving circuit breaker
17 In-house bus
18 Load breaker
19 Auxiliary motor
20 Instrument transformer
21 Tap changer controller
22 Automatic voltage regulator
23 Abnormal voltage detector
24 Current comparison judgment section
25 Reactive power comparison and determination unit
26 Power factor comparison judgment section

Claims (11)

An on-load tap-changing transformer connected to the power system via a transformer;
A large load connected via a circuit breaker to the secondary side of the load tap change transformer,
An instrument transformer for detecting voltage fluctuations in the in-house bus due to starting and stopping of this large load,
An automatic voltage regulator that compares the detected voltage from the instrument transformer with a predetermined set voltage,
In the control device of the on-load tap switching transformer for controlling the tap position of the on-load tap switching transformer based on the comparison result of the voltage values in the automatic voltage regulator,
A current transformer is provided in a system connecting the load-time tap switching transformer and the large load, and a current comparison and determination unit is provided for comparing a current value detected by the current transformer with a preset current range. When the detected current value is within the range, the current comparison determination unit determines that the large load is being started, and the load is determined regardless of the voltage value comparison result of the automatic voltage regulator. A control device for an on-load tap-changing transformer, wherein the control of the tap position of the tap-changing transformer is stopped. The current comparison determination unit stores a current range defined by an upper limit sudden change allowable current value and a lower limit sudden change allowable current value, and performs a comparison operation between the current range and a current value detected by the current transformer. 2. The control device according to claim 1, wherein said large load is determined to be in operation when it is within said range. An on-load tap-changing transformer connected to the power system via a transformer;
A large load connected via a circuit breaker to the secondary side of the load tap change transformer,
An instrument transformer for detecting voltage fluctuations in the in-house bus due to starting and stopping of this large load,
An automatic voltage regulator that compares the detected voltage from the instrument transformer with a predetermined set voltage,
In the control device of the on-load tap switching transformer for controlling the tap position of the on-load tap switching transformer based on the comparison result of the voltage values in the automatic voltage regulator,
A reactive power comparison determination for providing a current transformer in a system connecting the load tap switching transformer and the large load, and comparing a reactive power value detected by the current transformer with a preset reactive power value range. The reactive power comparison determination unit determines that the large load is being activated when the detected reactive power value is within the range, and compares the voltage values in the automatic voltage regulator. A control device for an on-load tap-changing transformer, wherein the control of the tap position of the on-load tap-changing transformer is stopped regardless of the result. The reactive power comparison and determination unit stores a power value range defined by an upper limit sudden change allowable reactive power value and a lower limit sudden change allowable reactive power value, and stores the power value range and the reactive power detected by the current transformer. 4. The control device for a load tap switching transformer according to claim 3, wherein a value is compared with a value, and when the value is within the range, the large load is determined to be activated. An on-load tap-changing transformer connected to the power system via a transformer;
A large load connected via a circuit breaker to the secondary side of the load tap change transformer,
An instrument transformer for detecting voltage fluctuations in the in-house bus due to starting and stopping of this large load,
An automatic voltage regulator that compares the detected voltage from the instrument transformer with a predetermined set voltage,
In the control device of the on-load tap switching transformer for controlling the tap position of the on-load tap switching transformer based on the comparison result of the voltage values in the automatic voltage regulator,
A current transformer is provided in a system connecting the load tap switching transformer and the large load, and a power factor comparison determination unit that compares a power factor detected by the current transformer with a preset power factor range. When the detected power factor is within the range, the power factor comparison / determination unit determines that the large load is being started, and the power factor comparison / determination unit determines whether the large load is in operation. A control device for an on-load tap-changing transformer, wherein the control of the tap position of the on-load tap-changing transformer is stopped. The power factor comparison and determination unit stores a power factor range defined by an upper-limit sudden change allowable power factor and a lower-limit sudden change allowable power factor, and compares the power factor range and the power factor detected by the current transformer. 6. The control device according to claim 5, wherein a comparison operation is performed, and when the load is within the range, it is determined that the large load is being started. 6. The control device for a load tap switching transformer according to claim 1, 3 or 5, wherein the automatic voltage regulator has a time limit characteristic line having at least two or more time limit curves. 8. The control device for a load tap switching transformer according to claim 7, wherein an anti-time limit characteristic line having at least two or more anti-time limit curves is on a voltage drop side with respect to a specified voltage. The tap position of the on-load tap-changing transformer whose primary side is connected to a power system via a transformer and whose secondary side is connected to a large load via a circuit breaker is used for an instrument provided on an in-house bus. In a control method of a load tap switching transformer for controlling by comparing and controlling a voltage value from a transformer and a voltage value set in advance in an automatic voltage regulator,
A step of detecting a change in the current value in the local bus when the large load is started or stopped, and an upper limit sudden change allowable current value and a lower limit sudden change preset in the current comparison determination unit in the detected current value. A step of determining whether the current value is within a range of an allowable current value, and a step of stopping control of a tap position regardless of a result of comparison of voltage values in the automatic voltage regulator when the current value is within the range. A method for controlling a tap change-over transformer under load, comprising: The tap position of the on-load tap-changing transformer whose primary side is connected to a power system via a transformer and whose secondary side is connected to a large load via a circuit breaker is used for an instrument provided on an in-house bus. In a control method of a load tap switching transformer for controlling by comparing and controlling a voltage value from a transformer and a voltage value set in advance in an automatic voltage regulator,
A step of detecting a change in the reactive power value in the local bus when the large load is started or stopped, and the detected reactive power value is set to an upper limit sudden change allowable reactive power preset in the reactive power comparison determination unit. Determining whether the value is within a range of a value and a lower limit sudden change permissible reactive power value, and controlling the tap position regardless of a comparison result of the voltage value in the automatic voltage regulator when the value is within the range. And controlling the on-load tap change transformer. The tap position of the on-load tap-changing transformer whose primary side is connected to a power system via a transformer and whose secondary side is connected to a large load via a circuit breaker is used for an instrument provided on an in-house bus. In a control method of a load tap switching transformer for controlling by comparing and controlling a voltage value from a transformer and a voltage value set in advance in an automatic voltage regulator,
A step of detecting a change in the power factor at the in-station bus at the time of starting or stopping the large load, and the detected power factor, and an upper limit abrupt variation power factor value preset in the power factor comparison determination unit. A step of determining whether the power factor is within a range of a lower limit abrupt power factor value, and stopping the tap position control irrespective of a voltage value comparison result in the automatic voltage regulator when the power factor value is within the range. Controlling the on-load tap-changing transformer.

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