JP4676369B2 - Voltage fluctuation compensation device - Google Patents

Description

  The present invention relates to a voltage fluctuation compensation device that is electrically connected to a welding machine load in which a welding current gradually increases when energization is started, and compensates for a power fluctuation generated in a distribution line by the welding machine.

  In a welding machine that gradually controls the welding current at the start of energization (slope control), the power consumption fluctuates every half cycle during the gradual increase control period, but the power consumption after the end of the gradual increase control period is a substantially constant value. Accordingly, the voltage drop of the distribution line greatly fluctuates during the gradual increase control period at the start of energization of the welding machine, and becomes a substantially constant value in the steady state after the gradual increase control period ends.

In Patent Document 1 below, by turning on / off individually the phase-advancing capacitors that are connected in parallel with the welding machine, have different capacities, and can switch the overall capacitor capacity in a plurality of stages by the combination thereof, A voltage fluctuation compensating device that compensates for a voltage drop that occurs in a distribution line during a gradual increase control period of a welding machine is disclosed.
That is, as shown in FIG. 4, the voltage fluctuation compensator 101 described in Patent Document 1 includes an instrument transformer 82 that detects a voltage of a distribution line, and a current transformer 81 that detects a current flowing through a welding machine 80. A compensation value detector 84 for calculating active power and reactive power generated in the welding machine 80 from outputs of the transformer 82 and the current transformer 81 and detecting a compensation value corresponding to a voltage fluctuation value generated in the distribution line; A phase advance capacitor circuit 90 including four reactor capacitor units 91 to 94 having series reactors 91a to 94a, semiconductor switches 91b to 94b, and phase advance capacitors 91c to 94c, respectively. A charge amount calculation unit 85 that calculates the required number of input stages of the phase advance capacitors 91 to 94 from the compensation value and outputs the calculation result to the command circuit 89, and a compensation value detection unit 84 The number of stages by phase advancing capacitor 91 through 94 corresponding to the issued compensation value and a command circuit 89 for outputting a signal for turning on / off the semiconductor switch 91b~94b as charged.
Japanese Patent Publication No. 8-2507

In the voltage fluctuation compensator 101 of the active power / reactive power detection method, the calculation of the active power / reactive power multiplies the welding machine current by the voltage of the distribution line and integrates it for half a cycle. Therefore, a half-cycle delay occurs in the detection of the compensation value obtained based on the active power / reactive power.
Further, in order to open and close the capacitor current without causing a transient phenomenon, it is necessary to insert a phase advance capacitor at a timing at which the capacitor terminal voltage and the circuit voltage match. Therefore, the phase-advancing capacitor circuit to be input has a capacitor capacity that compensates for active power and reactive power before half a cycle.

  Here, FIG. 5 shows a time chart regarding ON / OFF of the phase advance capacitor in the voltage fluctuation compensator 101 described above. As shown in FIG. 5, in the voltage fluctuation compensator 101, voltage fluctuation occurs due to the half-cycle delay in the above-described active power / reactive power calculation and the delay in waiting for the phase-advancing capacitor input timing.

As a method of introducing a phase advance capacitor without causing the above-mentioned delay, a phase advance capacitor is used in accordance with the start of energization of the welding machine by using an energization signal output slightly earlier than the actual energization timing of the welder. It is conceivable to use a voltage fluctuation compensator capable of supplying
In the voltage fluctuation compensating apparatus 102, as shown in FIG. 6, the energization synchronization output from the start of energization of the welder to the end of the gradual increase control period based on the energization signal output from the welding controller 80a of the welder 80. It has an energization synchronization signal output unit 86 for outputting a signal, and during the gradual increase control period, a constant capacity (for example, in the gradual increase control period) stored in advance in the input amount storage unit 87 in synchronization with the start of energization of the welding machine. A signal for turning on the phase-advancing capacitors 91c to 94c) is output to the command circuit 89.
Then, after the gradual increase control period of the welding machine 80 ends, the signal switching circuit 88 outputs a signal to the command circuit 89 to input the phase advance capacitors 91c to 94c corresponding to the number of steps calculated by the input amount calculation unit 85. Switch to.

FIG. 7 shows a time chart relating to on / off of the phase advance capacitor of the voltage fluctuation compensator 102 of the above-described energization synchronization signal and active / reactive power detection combined method.
As shown in FIG. 7, in the voltage fluctuation compensator 102, the voltage fluctuation due to the half cycle delay in the active power / reactive power calculation and the delay in waiting for the capacitor charging timing does not occur, but is input during the gradual increase control period. Since the capacity of the phase advance capacitor is constant, the voltage fluctuation can be made almost zero only during a certain period of the gradual increase control period. That is, a voltage rise occurs immediately after the start of energization, and a voltage drop occurs immediately before the gradual increase control period ends.

  Therefore, an object of the present invention is to provide a voltage fluctuation compensating device that can compensate for voltage fluctuation generated in the distribution line over the entire energization period of the welding machine.

  The voltage fluctuation compensator of the present invention is electrically connected to a welder load, and the voltage fluctuation generated in the distribution line by the welding machine controlled by the welding machine controller so that the welding current gradually increases in a predetermined period after the start of energization. A voltage fluctuation compensator that compensates for the load, a transformer for an instrument that detects a voltage of a distribution line electrically connected to the load of the welder, a current transformer that detects a load current, a series reactor, a semiconductor switch, And a plurality of reactor / capacitor units in which phase advance capacitors are connected in series, and a phase advance capacitor circuit connected in parallel with the welder load. Further, the voltage fluctuation compensating device receives an energization signal output from the welding machine controller before energization is completed before the energization of the welder, and after the energization of the welder is started, An energization synchronization signal output unit that outputs an energization synchronization signal until the end of the gradual increase control period, and a capacitance value of a phase advance capacitor to be gradually increased at predetermined time intervals from the start of reception of the energization synchronization signal. Corresponds to voltage fluctuations generated in the distribution line based on the input power gradually increasing part to be set and the active power and reactive power of the welding machine load calculated from the output of the instrument transformer and the output of the current transformer A compensation value detection unit for detecting a compensation value to be performed, an input amount calculation unit for calculating a capacitance value of a phase advance capacitor according to the compensation value detected by the compensation value detection unit, and the energization synchronization signal During the transmission, the signal switching circuit that outputs the capacitance value calculated by the input amount gradually increasing unit, and outputs the capacitance value calculated by the input amount calculating unit after receiving the energization synchronization signal, and the signal And a command circuit for outputting a signal for turning on / off the semiconductor switch based on the capacitance value outputted from the switching circuit. The energization synchronization signal output unit stores a delay time from when the energization signal is received to when the welding machine is energized, and a gradually increasing control period memory that stores the gradually increasing control period of the welding machine. A delay timer that counts a delay time until the start of energization of the welding machine based on the stored contents of the delay time storage unit after receiving the energization signal, and the gradual increase control period after the delay time is timed by the delay timer A gradual increase control period timer for timing the time until the gradual increase control period ends based on the storage contents of the storage unit, and an AND circuit for outputting an energization signal while the gradual increase control period timer is timing And a gradually increasing clock generating circuit for generating a pulse at a predetermined time interval, and a phase advance capacitor capacity capable of compensating for a voltage drop generated at the start of energization of the welding machine. Increasing starting volume storage unit for 憶, and has a counter circuit that counts up from said incremental start storage unit in the stored power capacitor capacity according to the pulse output from the incremental clock generation circuit.

  Further, in the voltage fluctuation compensator according to the present invention, the phase advance capacitors have different capacities, and the command circuit determines which one of the plurality of semiconductor switches to turn on from the input capacitance value. May be.

  Further, in the voltage fluctuation compensator of the present invention, when the capacity of the phase advance capacitor having the smallest capacity among the phase advance capacitors is set as the reference capacity C, the capacity of the i-th phase advance capacitor is the reference in the order of decreasing capacity. It may be a value obtained by multiplying the capacitance C by the power of 2 (i−1) (1 ≦ i ≦ n, (n: number of phase-advancing capacitors)).

  Furthermore, in the voltage fluctuation compensator of the present invention, it is preferable that the signal switching circuit stops output to the command circuit when the energization signal is input and the output of the energization signal is completed.

Therefore, the voltage fluctuation compensator of the present invention uses the energization signal output from the welding machine controller to delay the capacity of the phase advance capacitor circuit in accordance with the gradually increasing state of the welding current during the gradually increasing control period of the welding machine. During the period when the welding current fluctuation after the end of the gradual increase control period is reduced, the capacity of the phase advance capacitor circuit can be controlled with a compensation value according to the active power and reactive power generated in the welding machine. Therefore, the voltage fluctuation which generate | occur | produces in a distribution line over the whole electricity supply period of a welding machine can be compensated.
Also, compared to the case where multiple phase advance capacitors have the same capacity, the combination of multiple phase advance capacitors increases the types of values that can be taken by the entire phase advance capacitor circuit. The capacity of the phase advance capacitor circuit can be precisely controlled.
Furthermore, it is possible to change the capacity of the entire phase advance capacitor circuit at equal intervals.
In addition, after the energization of the welding machine is completed, it is possible to eliminate the occurrence of the delay in tripping of the phase advance capacitor due to the half cycle delay in the calculation of active power and reactive power.

  A preferred embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram in which a voltage fluctuation compensator according to the present embodiment is connected to a welder. As shown in FIG. 1, the voltage fluctuation compensation device 10 according to the present embodiment is connected in parallel with the welding machine 1. Here, the welding machine 1 is connected to an AC power source (not shown) and controlled by the welding machine controller 1a so that the welding machine current gradually increases for a predetermined period after the start of energization (see FIG. 3).

  The voltage fluctuation compensation device 10 includes an instrument transformer 11 that detects the voltage of the distribution line 3, a current transformer 13 that detects a current flowing through the welding machine 1, and a phase advance capacitor connected in parallel to the welding machine 1. Based on outputs from the circuit 20, the instrument transformer 11, the current transformer 13, and the welding machine controller 1a, switches for controlling on / off of four semiconductor switches 21b to 24b described later of the phase advance capacitor circuit 20 And a control unit 30.

The phase advance capacitor circuit 20 includes four reactor capacitor units 21 to 24 each including series reactors 21a to 24a, semiconductor switches 21b to 24b, and phase advance capacitors 21c to 24c. Each of the semiconductor switches 21b to 24b is connected in series with a phase advance capacitor and a DC reactor.
Here, in the present embodiment, the capacitances C1, C2, C3, and C4 of the phase advance capacitors 21c to 24c are set to be C1: C2: C3: C4 = 1: 2: 4: 8. Yes. Therefore, the capacitor capacity of the entire phase advance capacitor circuit 20 can be changed by 15 steps at equal intervals by the combination of the semiconductor switches 21b to 24b to be turned on.

  Next, the switch control unit 30 will be described in more detail with reference to FIG. FIG. 2 is a block diagram illustrating a schematic configuration of the switch control unit 30.

  As shown in FIG. 2, the switch control unit 30 controls the distribution line 3 based on the active power and reactive power generated in the welding machine load calculated from the output of the instrument transformer 11 and the output of the current transformer 13. A compensation value detector 31 for detecting a compensation value corresponding to the generated voltage fluctuation, and a phase advance required for compensating for the voltage fluctuation caused by the welding machine 1 according to the compensation value detected by the compensation value detector 31. And an input amount calculation unit 32 for calculating the capacitor capacity, that is, the number of input stages of the phase advance capacitor circuit 20.

Here, the voltage drop value ΔV generated when the welding machine 1 is in the energized state, which is necessary to obtain the compensation value and the required number of phase advance capacitor input stages, is the following (Equation 1), and the voltage rise value in the phase advance capacitor: ΔV _UP can be calculated by the following (Equation 2).

ΔV = P × (% R × cos θ +% X × sin θ) / (10 × 10 ⁶ ) (Formula 1)
However, ΔV: Voltage drop value [%], P: Apparent power of welding machine [VA],% R: Resistance impedance of distribution line (% per 10 MVA), cos θ: Power factor of welding machine,% X: Distribution It is the impedance corresponding to the reactance of the electric wire (% per 10 MVA), and sin θ is calculated by the power factor of the welding machine (θ = cos ⁻¹ θ).

ΔV _UP = Q ×% X / (10 × 10 ⁶ ) (Formula 2)
However, ΔV _UP : voltage increase value [%], Q: phase advance capacitor capacity [var],% X: impedance corresponding to reactance of distribution line (% per 10 MVA). (Equation 2) is derived from the fact that the power supplied by the phase advance capacitor in the above (Equation 1) = advanced reactive power only.

In the present embodiment, a method is adopted in which the total voltage drop due to the active power and reactive power shown in (Equation 1) is compensated by the phase advance reactive current supplied from the phase advance capacitor. That is, in this embodiment, since the voltage drop in the energized state of the welding machine 1 is compensated by inserting the phase advance capacitor, the voltage drop value ΔV in (Equation 1) immediately becomes the voltage rise value ΔV _UP in the phase advance capacitor. The relationship is equivalent to
Therefore, the compensation value detector 31 detects the voltage drop value ΔV or the voltage rise value ΔV _UP in the phase advance capacitor as the compensation value. Note that the voltage drop in (Equation 1) is the sum of the (active power) term of P × cos θ ×% R and the (reactive power) term of P × sin θ ×% X.
The method of calculating active power and reactive power from the input voltage and current is already used in another device or a conventionally known voltage fluctuation compensator, and the voltage fluctuation compensator of the present invention also calculates power using the same method. Later, the impedance can be multiplied to determine the voltage drop.

Therefore, by utilizing the fact that the voltage increase value ΔV _UP in the phase advance capacitor is obtained from (Equation 2), it is possible to calculate the phase advance capacitor capacity and the number of phase advance capacitor input stages required at the time of energization. Therefore, the input amount calculation unit 32 calculates the phase advance capacitor capacity and the number of phase advance capacitor input stages required during energization based on the above-described compensation value and (Equation 2).

  In addition, the switch control unit 30 receives an energization signal (see FIG. 3) output from the welding machine controller 1 a before the energization of the welding machine 1 is started before the energization is completed in the welding machine 1. An energization synchronization signal output unit 33 that outputs an energization synchronization signal (see FIG. 3) during the gradual increase control period T1 (see FIG. 3), and receives the energization synchronization signal and at predetermined time intervals from the start of receiving the energization synchronization signal In addition, a phase-advancing capacity 41 that sets the phase-advancing capacitor capacity necessary to compensate for voltage fluctuation, that is, the number of input stages of the phase-advancing capacitor circuit 20 to gradually increase, is provided.

Here, as shown in FIG. 2, the energization synchronization signal output unit 33 includes a delay time storage unit 34, a delay timer 35, a gradual increase control period storage unit 36, a gradual increase control period timer 37, and an AND circuit 38. .
The delay time storage unit 34 stores a delay time T2 (see FIG. 3) from when the energization signal is received to when the welding machine 1 starts energization. The delay timer 35 measures the time until the start of energization in the welding machine 1 based on the stored contents of the delay time storage unit 34 after receiving the energization signal. Further, the gradual increase control period storage unit 36 stores a gradual increase control period T1 in the welding machine 1. The gradual increase control period timer 37 is a time until the gradual increase control period T1 ends based on the storage contents of the gradual increase control period storage unit 36 after the time until the start of energization of the welding machine 1 is timed by the delay timer 35. Time. The AND circuit 38 outputs an energization synchronization signal while the gradual increase control period timer 37 keeps timing.

The input amount gradually increasing unit 41 includes a gradually increasing clock generating circuit 42, a gradually increasing start capacity storing unit 43, and a counter circuit 44.
The gradually increasing clock generation circuit 42 determines whether to gradually increase the number of input stages of the phase advance capacitor circuit 20 every half cycle or every cycle, and generates a pulse at each determined time interval. The gradual increase start capacity storage unit 43 stores the capacity of the phase advance capacitor that can compensate for the voltage drop that occurs when the welding machine 1 starts energization. While the energization synchronization signal is output, the counter circuit 44 outputs from the gradually increasing clock generation circuit 42 based on the number of input stages of the phase advance capacitor circuit 20 corresponding to the gradually increasing start capacity storage unit 43. The count is incremented step by step according to the pulse, and the count up is stopped when the output of the energization synchronization signal is stopped.

Further, the switch control unit 30 has a signal switching circuit 45 and a command circuit 46.
The energization synchronization signal is input to the signal switching circuit 45. While the energization synchronization signal is being received, the number of input stages determined by the input amount gradually increasing unit 41 is output to the command circuit 46, and after the energization synchronization signal reception is completed, The number of input stages calculated by the quantity calculation unit 32 is output to the command circuit 46.
Further, the energization signal output from the welding machine controller 1a is input to the signal switching circuit 45, and after receiving the energization signal, the output to the command circuit 46 is stopped. The command circuit 46 determines a combination of the four semiconductor switches 21b to 24b to be turned on based on the number of input stages output from the signal switching circuit 45, and outputs a signal for turning on / off the semiconductor switches 21b to 24b. To do.

  Next, the operation of the voltage fluctuation compensating apparatus 10 will be described with reference to FIG. FIG. 3 is a time chart of the control sequence of the voltage fluctuation compensator 10 of the present embodiment.

First, as shown in FIG. 3, the output of the energization signal from the welding machine controller 1a is started at time t1. The energization signal output at this time is input to the energization synchronization signal output unit 33 and the signal switching circuit 45.
Thereafter, when the delay time T2 stored in the delay time storage unit 34 elapses and the energization start time t2 of the welding machine 1 is reached, the output of the energization synchronization signal from the energization synchronization signal output unit 33 is started. The output of the energization synchronization signal from the energization synchronization signal output unit 33 is performed during the gradual increase control period T1 stored in the gradual increase control period storage unit 36, that is, until time t3.
The energization synchronization signal output at this time is input to the input amount gradually increasing unit 41 and the signal switching circuit 45.

Subsequently, the charging amount gradually increasing unit 41 inserts the phase-advancing capacitor so as to gradually increase at predetermined time intervals from time t2 when the energization synchronization signal is input to time t3 when the output of the energization synchronization signal ends. Set the number of steps.
Then, the signal switching circuit 45 outputs the number of input stages set by the input amount gradually increasing unit 41 to the command circuit 46, and the instruction circuit 46 sets the capacitor capacity of the entire phase advance capacitor circuit 20 by the input amount gradually increasing unit 41. On / off of the semiconductor switches 21b to 24b is controlled so as to have a capacity corresponding to the number of stages.
As a result, as shown in FIG. 3, the capacitor is turned on at the same time as the energization start time t2 of the welding machine 1, and the number of input stages of the phase advance capacitor circuit 20 gradually increases between time t2 and t3 corresponding to the gradual increase control period T1. To do.

Thereafter, when the gradual increase control period T1 ends and time t3 is reached, the signal switching circuit 45 ends the output to the command circuit 46 of the input stage number set by the input amount gradual increase unit 41, and the instrument transformer 11 and the variable transformer 11 are changed. The output to the command circuit 46 of the number of input stages calculated by the input amount calculation unit 32 that calculates the number of input stages of the required capacitor capacity according to the compensation value detected based on the output of the flow device 13 is started.
Furthermore, when the output of the energization signal from the welding machine controller 1a is completed at time t4, the signal switching circuit 45 stops the output to the command circuit 46 of the number of input stages calculated by the input amount calculation unit 32. Therefore, as shown in FIG. 3, the capacitor is removed after the energization end time t4 in the welding machine 1.

As described above, in the voltage fluctuation compensation device 10 of the present embodiment, the energization synchronization signal output unit 33 is synchronized with the energization during the gradual increase control period of the welding machine 1 based on the energization signal output from the welding machine controller 1a. Output a signal.
Then, the input amount gradually increasing unit 41 receives the energization synchronization signal, and sets the number of input stages of the phase advance capacitor circuit 20 so as to gradually increase every predetermined time interval from the start of energization synchronization signal reception.
On the other hand, the input amount calculation unit 32 compensates for voltage fluctuation caused by the welding machine 1 from the compensation value detected by the compensation value detection unit 31 based on the output of the instrument transformer 11 and the output of the current transformer 13. The number of input stages of the phase advance capacitor circuit 20 necessary for the calculation is calculated.
Further, when the signal switching circuit 45 is receiving the energization synchronization signal from the energization synchronization signal output unit 33, the number of input stages set by the input amount gradually increasing unit 41, and after receiving the energization synchronization signal, the input amount calculation unit The input amount calculated by 32 is output to the command circuit 46. The command circuit 46 determines a combination of the four semiconductor switches 21b to 24b to be turned on based on the input number of input stages, and outputs a signal for turning on / off the semiconductor switches 21b to 24b.
Therefore, by using the energization signal output from the welding machine controller 1a, the capacity of the phase advance capacitor circuit 20 during the gradually increasing control period of the welding machine 1 is controlled without delay according to the gradually increasing state of the welding current, and gradually increased. In the period when the fluctuation of the welding current becomes small after the end of the control period, the capacity of the phase advance capacitor circuit 20 can be controlled with a compensation value according to the active power and reactive power generated in the welding machine 1.
Therefore, the voltage fluctuation which generate | occur | produces in the distribution line 3 over the whole electricity supply period of the welding machine 1 can be compensated.

  Moreover, in the voltage fluctuation compensating apparatus 10 of this Embodiment, the phase advance capacitors 21c-24c have a mutually different capacity | capacitance. Thereby, compared with the case where the capacitors having the same capacity are included in the phase advance capacitors 21c to 24c, the capacity of the entire phase advance capacitor circuit 20 can be taken by the combination of the four phase advance capacitors 21c to 24c. More types of values. Therefore, the capacity of the phase advance capacitor circuit 20 can be precisely controlled.

  Further, in the voltage fluctuation compensating apparatus 10 of the present embodiment, the capacitances C1, C2, C3, and C4 of the phase advance capacitors 21c to 24c are C1: C2: C3: C4 = 1: 2: 4: 8, respectively. Is set to Therefore, it is possible to change the capacity of the entire phase advance capacitor circuit 20 at equal intervals in 15 steps.

  Furthermore, in the voltage fluctuation compensator 10 of the present embodiment, when the energization signal is input to the signal switching circuit 45 and the output of the energization signal is finished, the signal switching circuit 45 stops the output to the command circuit 46. To do. Therefore, after the energization in the welding machine 1 is completed, it is possible to eliminate the occurrence of the delay in tripping of the phase advance capacitor due to the half cycle delay in the calculation of active power and reactive power.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made as long as they are described in the claims. Is something. For example, in the above-described embodiment, the case where the phase advance capacitor circuit 20 includes four reactor capacitor units 21 to 24 has been described. However, the number of reactor capacitor units included in the phase advance capacitor circuit 20 is four. It is not limited to one.

  In the above-described embodiment, the capacitances C1, C2, C3, and C4 of the phase advance capacitors 21c to 24c are set so that C1: C2: C3: C4 = 1: 2: 4: 8. However, the ratio of the capacitors C1 to C4 is not limited to this. For example, the capacitors C1 to C4 may be equal to each other.

  Further, in the above-described embodiment, the case where the signal switching circuit 45 stops the output to the command circuit 46 when the energization signal is input to the signal switching circuit 45 and the output of the energization signal is finished has been described. This is not a limitation. The configuration may be such that the energization signal is not input to the signal switching circuit 45.

  Further, in the above-described embodiment, the method of setting the initial charging amount of the phase advance capacitor circuit 20 in advance and increasing it step by step has been described, but the phase advance capacitor circuit 20 of the welder 1 during the gradual increase control period has been described. The input step number gradual increase control unit is not limited to this. For example, various methods such as separately storing the number of steps to be added and increasing the number of additions, storing the input amount in a memory in advance, and realizing arbitrary pattern control, etc. Approach can be taken.

  In addition, the specific calculation method of the compensation value and the necessary number of phase-advancing capacitor input stages is not limited to that described in the above-described embodiment, and a known method can be appropriately employed.

It is the figure which connected the voltage fluctuation compensation apparatus which concerns on embodiment of this invention to the welding machine. It is a block diagram of schematic structure of the switch control part shown in FIG. It is a time chart of the control sequence of the voltage fluctuation compensation apparatus shown in FIG. It is the figure which connected the voltage fluctuation compensator of the conventional combined use method of active power and reactive power detection to the welding machine. It is a time chart of the control sequence of the voltage fluctuation compensation apparatus shown in FIG. It is the figure which connected the voltage fluctuation compensation apparatus of the conventional energization synchronous signal and reactive power / active power detection combined use system to the welding machine. It is a time chart of the control sequence of the voltage fluctuation compensation apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Welding machine 1a Welding machine controller 3 Distribution line 10 Voltage fluctuation compensation apparatus 11 Instrument transformer 13 Current transformer 20 Phase advance capacitor circuit 21-24 Reactor capacitor unit 21a-24a Series reactor 21b-24b Semiconductor switch 21c-24c Progression Phase capacitor 30 Switch control unit 31 Compensation value detection unit 32 Input amount calculation unit 33 Energization synchronization signal output unit 34 Delay time storage unit 36 Gradually increasing control period storage unit 41 Input amount gradually increasing unit 45 Signal switching circuit 46 Command circuit

Claims (4)

A voltage fluctuation compensator that is electrically connected to a welder load and compensates for voltage fluctuations generated in a distribution line by the welding machine controlled by a welding machine controller so that a welding current gradually increases in a predetermined period after the start of energization. And
An instrument transformer for detecting a voltage of a distribution line electrically connected to the welder load;
A current transformer for detecting the load current;
A plurality of reactor / capacitor units each including a series reactor, a semiconductor switch, and a phase advance capacitor connected in series; and a phase advance capacitor circuit connected in parallel with the welder load;
The energization signal output from the welding machine controller is received before the energization is completed before the energization is started in the welding machine, and the energization synchronization is performed after the energization of the welding machine is started until the end of the gradual increase control period of the welding machine. An energization synchronization signal output unit for outputting a signal;
An input amount gradual increase unit that sets the capacitance value of the phase advance capacitor to be gradually increased every predetermined time interval from the start of reception of the energization synchronization signal;
A compensation value for detecting a compensation value corresponding to a voltage fluctuation generated in the distribution line based on the active power and reactive power of the welding machine load calculated from the output of the instrument transformer and the output of the current transformer A detection unit;
An input amount calculation unit that calculates the capacitance value of the phase advance capacitor according to the compensation value detected by the compensation value detection unit;
While receiving the energization synchronization signal, a signal switching circuit that outputs the capacitance value calculated by the input amount gradually increasing unit and outputs the capacitance value calculated by the input amount calculation unit after receiving the energization synchronization signal When,
A command circuit for outputting a signal for turning on / off the semiconductor switch based on the capacitance value output from the signal switching circuit;
A delay time storage unit that stores a delay time from when the energization synchronization signal output unit receives the energization signal until the start of energization of the welding machine; a gradually increasing control period storage unit that stores a gradually increasing control period of the welding machine; After receiving the energization signal, based on the stored contents of the delay time storage unit, a delay timer for measuring the delay time until the start of energization of the welding machine, and after the delay time is measured by the delay timer, the gradually increasing control period storage unit The incremental control period timer that measures the time until the gradual increase control period ends, and an AND circuit that outputs an energization signal while the gradual increase control period timer counts,
The incremental amount gradually increasing unit generates a gradually increasing clock generating circuit for generating a pulse at predetermined time intervals, a gradually increasing start capacity storing unit for storing a phase advance capacitor capacity capable of compensating for a voltage drop that occurs at the start of energization of the welding machine, and the gradually increasing unit A voltage fluctuation compensator, comprising: a counter circuit that counts up according to a pulse output from the gradually increasing clock generation circuit from a phase advance capacitor capacity stored in a start capacity storage unit.   The said phase advance capacitor has a mutually different capacity | capacitance, The said command circuit determines what to turn ON among the said some semiconductor switch from the inputted capacitance value. Voltage fluctuation compensation device.   When the capacity of the phase advance capacitor having the smallest capacity among the phase advance capacitors is defined as the reference capacity C, the capacity of the i-th phase advance capacitor is increased to the (i-1) th power of the reference capacity C in order of increasing capacity. The voltage fluctuation compensation device according to claim 2, wherein a value obtained by multiplying by (1 ≦ i ≦ n, (n: number of phase-advancing capacitors)) is obtained.   The said signal switching circuit stops the output to the said command circuit, when the said energization signal is input and the output of the said energization signal is complete | finished, The any one of Claims 1-3 characterized by the above-mentioned. Voltage fluctuation compensation device.

Images