CN102288880A - Frequency-changing resonant withstand voltage testing device - Google Patents

Abstract

The invention discloses a withstand voltage test device, in particular to a frequency conversion resonance withstand voltage test device capable of adjusting the induced withstand voltage of a large transformer and the frequency of a partial discharge test within a certain range. The variable frequency resonance withstand voltage test device includes a variable frequency power supply and an intermediate transformer, wherein reactors are connected in parallel at both ends of the high voltage winding of the intermediate transformer. When the present invention performs induction withstand voltage and partial discharge on large-scale power transformers, no matter how different the voltage level and capacity of the tested transformer are, the size can be adjusted through the adjustable compensating reactor, so that the test frequency of the frequency conversion power resonant device is guaranteed to be between 100 and 100. 250Hz working frequency. Therefore, various large-scale power transformers can perform induction withstand voltage and partial discharge work smoothly. The input cost of experimental equipment is reduced.

Description

Frequency conversion resonance withstand voltage test device

technical field

The invention relates to a withstand voltage test device, in particular to a variable frequency resonance withstand voltage test device capable of adjusting the induced withstand voltage of a large transformer and the frequency of a partial discharge test within a certain range.

Background technique

Increase the frequency of the power supply and reduce the excitation current to achieve the purpose of increasing the applied voltage, which is suitable for the withstand voltage test of the transformer with graded insulation. If the transformer under test is properly wired, the main and longitudinal insulation of the transformer can be assessed at the same time. In order to prevent the saturation of the transformer core under test, the test frequency should be increased, and the frequency should not be too high. Figure 1 is the principle wiring diagram of the current resonant withstand voltage test device. When the resonant withstand voltage test device of this structure is used for inductive withstand voltage and partial discharge of large power transformers, due to the different voltage levels and capacities of the test products, frequency conversion is often required. The test frequency of the power resonant device is difficult to guarantee the working frequency of 100-250Hz, which cannot meet the requirements of various large-capacity transformer test frequencies. This leads to the need for different variable frequency power resonant devices to measure transformers with different voltage levels and capacities, which greatly increases the equipment investment cost of large-scale power transformers for inductive withstand voltage and partial discharge test devices, which has become a problem for the technology in this field. personnel technical problems.

Contents of the invention

In order to solve the above problems, the present invention provides a frequency conversion resonant withstand voltage test device, the purpose of which is to solve the problem that the existing withstand voltage test resonant devices in various large-capacity transformer tests cannot meet the requirements of the test frequency. The present invention enables different capacities, The resonant test frequency of the tested transformers with different rated voltages can meet the working requirements.

In order to achieve the above purpose, the present invention is achieved through the following technical solutions.

The variable frequency resonant withstand voltage test device includes a variable frequency power supply and an intermediate transformer, wherein a reactor is connected in parallel at both ends of the high voltage winding of the intermediate transformer.

The reactor described is an adjustable compensating reactor.

The adjustable compensating reactor is 1-2 groups.

When the adjustable compensating reactors are in two groups, they are connected in series.

The adjustable compensating reactor is provided with three taps, the three taps are respectively connected to the coil through wires, the coil is arranged in the insulating cylinder shell, and the insulating cylinder shell is filled with insulating oil, and the three taps and the reactor coil first The end and the end are installed on the outer wall of the insulating cylinder shell.

For the three taps, the first tap is set at 1/5 of the length of the reactor coil, the second tap is set at 2/5 of the length of the reactor coil, and the third tap is set at 1/5 of the length of the reactor coil. 2 positions.

The insulating cylinder shell is installed on the insulating base.

Owing to adopting above-mentioned technical scheme, the present invention has following advantage and effect:

When the present invention performs induction withstand voltage and partial discharge on large-scale power transformers, no matter how different the voltage level and capacity of the tested transformer are, the size can be adjusted through the adjustable compensating reactor, so that the test frequency of the frequency conversion power resonant device is guaranteed to be between 100 and 100. 250Hz working frequency. Therefore, various large-scale power transformers can perform induction withstand voltage and partial discharge work smoothly. The input cost of experimental equipment is reduced.

Description of drawings

Fig. 1 is a circuit schematic diagram of an existing resonant withstand voltage test device.

Fig. 2 is a schematic circuit diagram of the frequency conversion resonant withstand voltage test device of the present invention.

Fig. 3 is a schematic circuit diagram of the adjustable compensating reactor in Fig. 2 .

Fig. 4 is a schematic structural diagram of the adjustable compensating reactor in Fig. 2 .

In the figure, 1. Frequency conversion power supply, 2. Intermediate transformer, 3. Adjustable compensating reactor, 4. Coil, 5. Insulation cylinder shell, 6. Reactor coil head end, 7. Reactor coil end, 8. First Tap, 9, the second tap, 10, the third tap, 11, the insulating base.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited by the embodiments.

As shown in Figure 2, the frequency conversion resonant withstand voltage test device of the present invention includes a frequency conversion power supply 1 and an intermediate transformer 2, and a reactor is connected in parallel at both ends of the high voltage winding of the intermediate transformer 2, and the reactor can be an adjustable compensation reactor 3 , which works best.

As shown in Figures 3 and 4, the above-mentioned adjustable compensating reactor 3 is provided with three taps, and the three taps are respectively connected to the coil 4 through wires, the coil 4 is arranged in the insulating cylinder shell 5, and the insulating cylinder shell 5 is filled with Insulating oil, three taps, the head end 6 of the reactor coil and the end 7 of the reactor coil are installed on the outer wall of the insulating cylinder shell 5 . Among the three taps, the first tap 8 is set at 1/5 of the length of the reactor coil 4, the second tap 9 is set at 2/5 of the length of the reactor coil 4, and the third tap 10 is set at the length of the reactor coil 4 1/2 of the position. The insulating cylinder shell 5 is installed on the insulating base 11 .

The adjustable compensating reactor 3 is designed as an air-core structure and an oil-immersed self-cooling type. The adjustable compensating reactor 3 can be stacked in two sections, can also be used alone or in series, and can also be flexibly used by using reactor taps. The epoxy resin insulating cylinder shell 5 has sufficient electrical and mechanical strength, necessary heat dissipation capacity and margin for thermal expansion and contraction of oil. The insulating base of the reactor has sufficient stability and can bear the total weight of the two reactors, which is convenient for disassembly and assembly, and has a lifting device.

When the adjustable compensation reactor is fully applied, the compensation inductance is the smallest; when the third tap 10 is used, the compensation inductance coil is the smallest, and the compensation inductance is the largest.

By changing the parameters of the circuit or the frequency of the medium-voltage power supply, the circuit can be tuned to resonance, and at the same time, a current whose amplitude is much larger than the power supply current and whose waveform is close to a sine wave is applied to the test object. As shown in Figure 2, when the low-voltage side of the transformer is 10kV, 1 or 2 adjustable compensating reactors can be used. When the low-voltage side of the transformer is 66kV, two adjustable compensating reactors can be connected in series, the midpoint is grounded, and the adjustable compensating reactor is used during operation. The inductance current of the transformer and the test product, that is, the capacitive current at the entrance of the tested transformer cancel each other out. Small-capacity tested transformers such as 60000kVA-120000kVA can be compensated by reactors without taps, and large-capacity tested transformers such as 180000kVA-240000kVA can be used with taps. Adjustable compensating reactor for compensation.

In the face of different test products, the combination of adjustable compensating reactors adopts the method of inverse calculation. First determine whether the adjustable compensation reactor is combined in series or parallel by the test voltage, and then determine the capacity range of the test product by the inductance of the adjustable compensation reactor and the system operating frequency of 100-250Hz.

The test voltage of the test product must be guaranteed to be less than or equal to the rated voltage of the reactor. If a single reactor cannot meet the voltage requirement, two reactors can be connected in series to meet the test voltage. Determine the allowable test frequency range (fmin, fmax) of the test product, satisfying 100 Hz≤fmin≤fmax≤250Hz. According to the reactor inductance L (single or two in series), the allowable test frequency range of the test product (fmin, fmax), determine the allowable range value of the capacitance of the test product (Cmin, Cmax). If the capacitance of the test product is too large or too small, the tap method of changing the compensation inductance is used to change the size of the compensation inductance.

The parameters of the adjustable compensation reactor 3 of the present invention are as follows: rated voltage, 70kV; rated current, 6A; inductance, 6H (±10%); rated capacity, 420kVAR; insulation level, 84kV/1min; 5min; working frequency range, 20-300Hz; allowable temperature rise, at rated capacity, coil temperature rise ≤ 65K, oil temperature rise ≤ 55K; partial discharge level, rated voltage ≤ 10pC; allowable operating time: allowed at rated output current Continuous operation for 180min; Dimensions and weight: Weight: 350kg, Dimensions: Φ650×700 (mm).

Claims (7)

1. Frequency conversion resonance withstand voltage test device, which comprises frequency conversion power supply and intermediate transformer, and is characterized in that a reactor is connected in parallel at both ends of the high voltage winding of said intermediate transformer. 2. The frequency conversion resonance withstand voltage test device according to claim 1, characterized in that the reactor is an adjustable compensation reactor. 3. The variable frequency resonant withstand voltage test device according to claim 2, characterized in that there are 1-2 groups of adjustable compensating reactors. 4. The frequency conversion resonance withstand voltage test device according to claim 3, characterized in that when the adjustable compensating reactors are in two groups, they are connected in series. 5. The variable frequency resonance withstand voltage test device according to claim 2, 3 or 4, characterized in that the adjustable compensation reactor is provided with three taps, and the three taps are respectively connected to the coil through wires, and the coil is arranged on In the insulating cylinder shell, the insulating cylinder shell is filled with insulating oil, and the first end and the end of the three taps and the reactor coil are installed on the outer wall of the insulating cylinder shell. 6. The variable frequency resonant withstand voltage test device according to claim 5, characterized in that the three taps, the first tap is set at 1/5 of the length of the reactor coil, and the second tap is set at the reactor coil 2/5 of the length, and the third tap is located at 1/2 of the reactor coil length. 7. The frequency conversion resonant withstand voltage test device according to claim 5, characterized in that the insulating cylinder shell is installed on the insulating base.

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