JP3245524B2 - Interval power supply device and power supply method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interval power supply device and a power supply method using the same. About the method.

[0002]

2. Description of the Related Art When a new power cable is laid, a completion test such as partial discharge measurement is performed to test the performance of the power cable. To perform the completion test, power is applied to the power cable using a power application device that uses direct current, alternating current, or ultra-low frequency.

[0003] Among these power supply methods, in a power supply device using an AC power supply, a charging current is generated in the cable by applying a test AC voltage to the power cable, and the charging current is generated based on the charging current. There is an inconvenience that heat is generated from the measured object and the transformer.

In order to eliminate the heat generated by the charging current, there has been proposed a method in which a simulated alternating current is created from a DC voltage generated by a DC power supply to apply power, but a special DC power supply is required. In addition, there is a problem that the scale of the power cutoff unit becomes large.

[0005] FIG.
3 shows an interval power supply device proposed by the present applicant as Japanese Patent Application No. Hei 6-154155 on the third day. The transformer 5 has a variable inductance mechanism and is connected to the primary winding 6 of the transformer 5 to reduce the commercial frequency. An AC power supply 1 for generating an AC power, a switching circuit 2 connected in series to the AC power supply 1 and thyristors 3 and 4 connected in parallel, and a coupling capacitor Ck connected to the secondary winding 7 of the transformer 5.
8, an insulator Cx9 of a test cable which forms a resonance circuit, a detection impedance 10 for partial discharge measurement, a partial discharge measuring instrument 11 connected to the detection impedance 10, and an AC power supply 1. A controller 12 for fetching zero-cross phase information, controlling on / off of the thyristor at the time of the zero-cross phase, and controlling the partial discharge measuring device 11; And 4 are switched to generate an AC voltage (interval wave) having an arbitrary intermittent period. According to the interval power supply device, the average charging current is reduced by intermittently applying the AC voltage to the power cable.

On the other hand, JP-A-2-243973 discloses a test apparatus for reducing a charging current after a test. This test apparatus includes an AC power supply connected to a primary winding of a transformer, a resistor arranged in parallel with the primary winding,
There is a switch to connect this resistor to the primary winding,
Based on the completion of the partial discharge test, stop applying power to the sample connected to the secondary winding side and turn on the switch at the same time to configure a closed circuit with the resistor and the primary winding, and connect it to the secondary winding side The energy stored in the secondary winding is dissipated by consuming the stored electric energy in this closed circuit.

[0007]

However, according to the conventional interval power supply device, the AC voltage is intermittently applied to the power cable. However, even after the supply of power is stopped, the charging current flows through the resonance circuit. , The heat generation of the transformer and the DUT continues. On the other hand, according to the test apparatus disclosed in Japanese Patent Application Laid-Open No. 2-243973, a large current flows instantaneously through the switch and the resistor, and the load on these switches and the resistor increases. Since such a power application device is sometimes used temporarily, it is desirable that the power application device be small and lightweight. However, as described above, it is necessary to reduce the size and weight of the power application device from the viewpoint of heat resistance and durability. There is a problem that is difficult. In addition, since only the energy stored on the secondary side is dissipated, power consumption cannot be reduced. Therefore,
SUMMARY OF THE INVENTION It is an object of the present invention to provide an interval power supply apparatus capable of suppressing heat generation of a transformer and a device under test and reducing the size and weight thereof, and a power supply method using the same.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a first switching device provided between an AC power supply and an input side of a transformer is provided in order to suppress heat generation of a transformer and a device under test and to reduce the size and weight. Circuit, a braking resistor provided on the input side or output side of the transformer, a second switching circuit provided between the input side or output side of the transformer and the braking resistor, A voltage detection circuit for detecting a voltage on the output side, and an intermittent charging voltage applied to an electric device by turning on the first switching circuit for a predetermined time, and after the first switching circuit is turned off, detecting the voltage. When the circuit detects that the voltage on the output side has dropped to a value of a predetermined ratio of the intermittent charging voltage, the second switching circuit is turned on from off and the free oscillation on the output side is caused by the braking resistor. Force reduction Providing an interval division collector having a control circuit for.

In the above-mentioned interval power supply device, the electric equipment forms a resonance circuit on the transformer side, and the predetermined ratio is 1
Desirably, the damping resistance is set to be in the range of 00 to 80%, and the braking resistor is desirably connected in series to the tertiary winding of the transformer. Further, the control circuit may be configured to turn on / off the first switching circuit at a zero cross point of the AC power supply.

Further, in order to achieve the above-mentioned object, the present invention intermittently applies an AC voltage to an electric device from an AC power supply via a transformer, and stops the application of the AC voltage. Measuring an applied voltage of the electric device generated based on free vibration in the voltage applying circuit including, when the applied voltage based on the free vibration becomes a predetermined ratio of the applied voltage of the intermittent AC voltage. An interval power supply method is provided in which a current absorption resistor is connected to the power supply circuit to forcibly attenuate the free vibration.

In the above-described interval power application method, it is desirable to connect a current absorption resistor to the power application circuit when the predetermined ratio becomes 100 to 80%. However, it is desirable to turn on and off at the zero cross point of the AC voltage.

According to the present invention, when the voltage of the resonance circuit connected to the secondary winding of the transformer falls to a predetermined ratio value of the intermittent charging voltage, the braking resistance is set based on the output from the control circuit. The connection forcibly attenuates the resonance voltage at which the power application effect cannot be obtained. When the braking resistor is connected to the tertiary winding of the transformer, a free oscillation current based on the resonance voltage generated in the secondary winding is absorbed by the braking resistor via the transformer.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of an interval power supply apparatus according to the present invention. Portions having the same configuration and function as those of the prior art are denoted by the same reference numerals, and duplicate description will be omitted.

[0014] Figure 1 shows an interval division photoelectric device according to one embodiment of the present invention, the AC power source 1 for generating an AC is connected to the 6-side primary winding of the transformer 5 (AC50H _Z)
And thyristors 3 and 4 connected in series to AC power supply 1
Are connected in parallel with the switching circuit 2 and the transformer 5.
A test cable line 13 connected to the secondary winding 7 side of
A variable reactor 14 for varying the resonance frequency of the secondary-side resonance circuit, a braking resistor 16 connected to the tertiary winding 15 of the transformer 5, and a thyristor 17 and 18 connected in series to the braking resistor 16 and arranged in parallel A switching circuit 19, a cable connection portion 21 provided with a detection electrode 20 for partial discharge measurement, a voltage measuring device 22 for measuring a voltage of a circuit on the secondary winding 7 side, and a connection to the detection electrode 20. The phase information is fetched from the measured partial discharge meter 11 and the AC power supply 1, and the thyristors 3 and 4 of the switching circuit 2 are turned on and off at the time of a zero cross phase. Thyristor 17,
18 for controlling on and off, and for measuring partial discharge 1
And a controller 12 for controlling the controller 1.

In the above-described interval power supply device, a resonance circuit is configured by the transformer 5, the variable reactor 14, and the cable under test 13, and the variable reactor 14 is resonated with the resonance circuit at the frequency of the AC power supply 1. Adjust it.

FIG. 2 is a timing chart showing the operation of the interval power supply device of the present invention. Hereinafter, the interval power supply method of the present invention will be described with reference to FIGS. By turning on the AC power supply 1, FIG.
A power supply voltage having the output waveform shown in (1) is generated.

FIG. 2B shows the switching timing of the switching circuit 2. By turning on the switching circuit 2 for 1.5 cycles from the zero cross phase of the power supply voltage (basically, an arbitrary cycle). The primary current as shown in FIG. 2C flows through the primary side of the transformer 5.

FIG. 2D shows the applied voltage and the voltage based on the free oscillation after the application of the power, and 1.5% after the switching circuit 2 is turned on in synchronization with the zero cross phase of the power supply voltage.
When the switching circuit 2 is turned off in synchronization with the zero cross phase in the cycle, free vibration is generated based on the capacitance C of the test cable line 13 on the secondary winding 7 side and the inductance L of the transformer 5, and the resonance circuit Current continues to flow in.

The current based on the free vibration is supplied to the transformer 5
Alternatively, it is attenuated over time by being consumed as heat of the variable reactor 14. In this decay process, the imposed voltage value output from the voltage measuring device 22 is 1
When the value becomes 00 to 80%, a control signal is output from the controller 12 to turn on the switching circuit 19 as shown in FIG. 2 (5), and the braking resistor 16 is connected to the tertiary winding 15 of the transformer 5. .

As a result, a current based on the free vibration flowing through the resonance circuit flows through the tertiary winding 15 via the transformer 5 and is consumed by the braking resistor 16 to cause a forced damping as shown in FIG. .

As described above, the damping characteristic of the free vibration generated in the resonance circuit is changed by turning on the switching circuit 19, connecting the braking resistor 16 and consuming the current braking resistor 16 flowing through the resonance circuit. be able to. That is, since the damping time is shortened by connecting the braking resistor 16 and forcibly converging the free vibration, the energizing time to the transformer 5 and the variable reactor 14 is shortened.

Therefore, since the transformer and the variable reactor are not exposed to heat for a long time, it is possible to select a small-sized one, and it is possible to reduce the size and weight of the power application device.

In the above embodiment, the interval charging device of the present invention is used for partial discharge measurement. In this case,
From the primary winding 6 connected to the AC power supply 1 to the transformer 5
Secondary winding 7 connected to test cable 13 via
Is applied, a partial discharge pulse generated in the test cable 13 is input to the partial discharge measuring device 11 from the detection electrode 20 provided in the cable connection portion 21. The partial discharge measurement device 11 analyzes the partial discharge measurement data based on the control signal of the controller 12 to which the phase information of the AC power supply 1 is input.

In the above embodiment, the damping characteristic of the free vibration generated on the secondary winding 7 side is varied by connecting the braking resistor 16, but as another method, for example, the thyristors 17, 18 By performing the phase control by adjusting the control timing, it is possible to control the waveform or the decay time when the braking resistor 16 is connected. Also,
The thyristor can be replaced by another mechanical switch, and the braking resistor 16 may be a voltage-dependent resistor or a variable resistor. The cable under test 13 may be an electrical device such as a transformer or a switch, regardless of whether it is being laid or wound around a drum.

[0025]

As described above, according to the interval power supply device and the power supply method using the same according to the present invention, the electrical equipment connected to the secondary side of the transformer is intermittently charged for a predetermined time period, A control circuit is provided to connect a braking resistor when the voltage based on the free vibration drops to a predetermined ratio with respect to the imposed voltage. it can. Further, since the ON time of the AC voltage can be shortened, power can be saved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an interval power supply device according to an embodiment of the present invention.

FIG. 2 is a timing chart showing an interval charging method according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a conventional interval power supply device.

[Explanation of symbols]

 1, AC power supply 2, switching circuit 3, thyristor 4, thyristor 5, transformer 6, primary winding 7, secondary winding 8, coupling capacitor 9, insulator 10, detection impedance 11, partial discharge measuring instrument 12, controller 13 , Test cable line 14, variable reactor 15, tertiary winding 16, braking resistor 17, thyristor 18, thyristor 19, switching circuit 20, detection electrode 21, cable connection part 22, voltage measuring instrument

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kan Endo 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture Inside the Power System Research Laboratories, Hitachi, Ltd. JP-A-2-24397 (JP, A) JP-A-5-137351 (JP, A) JP-A-7-174812 (JP) , A) JP-A-7-333290 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/12

Claims (7)

(57) [Claims] 1. A first switching circuit provided between an AC power supply and an input side of a transformer, a braking resistor provided on an input side or an output side of the transformer, and an input side of the transformer. Alternatively, a second switching circuit provided between an output side and the braking resistor, a voltage detection circuit for detecting a voltage on an output side of the transformer, and turning on the first switching circuit for a predetermined time period to generate electricity After the first switching circuit is turned off, the voltage detection circuit detects that the voltage on the output side has dropped to a value of a predetermined ratio of the intermittent charging voltage to the device. And a control circuit for turning on the second switching circuit from off to on to forcibly attenuate the free vibration on the output side by the braking resistor. 2. A first switching circuit provided between an AC power supply and an input side of a transformer, a braking resistor provided on an input side or an output side of the transformer, and an input side of the transformer. Alternatively, a second switching circuit provided between an output side and the braking resistor, a voltage detection circuit for detecting a voltage on an output side of the transformer, and turning on the first switching circuit for a predetermined time period to generate electricity When an intermittent charging voltage is applied to a device, and after the first switching circuit is turned off, the voltage detection circuit detects that the voltage on the output side has dropped to 100 to 80% of the intermittent charging voltage. And a control circuit for turning on and off the second switching circuit from off to forcibly attenuating the free vibration on the output side by the braking resistor. 3. The interval power supply device according to claim 1, wherein the electric device forms a resonance circuit on an output side of the transformer. 4. The interval charging device according to claim 1, wherein the braking resistor is connected in series to a tertiary winding of the transformer. 5. The interval power supply device according to claim 1, wherein the control circuit turns on and off the first switching circuit at a zero crossing point of the AC power supply. 6. An intermittent application of an alternating voltage from an alternating current power supply to an electric device via a transformer, and based on free vibration in a voltage application circuit including the electric device after the application of the alternating voltage is stopped. Measuring the applied voltage of the electrical equipment that occurs, connecting a current absorbing resistor to the applied circuit when the applied voltage based on the free vibration has a predetermined ratio of the applied voltage of the intermittent AC voltage. Wherein the free vibration is forcibly attenuated by using the method. 7. The interval charging method according to claim 6, wherein said predetermined ratio is 100 to 80%.