Embedded non-excitation voltage regulation broadband test transformer

Abstract

The invention discloses an embedded non-excitation voltage regulation broadband test transformer, which comprises a high-voltage side coil capable of carrying out on-load voltage regulation and a low-voltage side coil capable of carrying out gear regulation, the X1, the X2, the X3, the X4, the X5, the X6 and the X7 are selection switches on the high-voltage side, and the total number of the selection switches is seven; the low-voltage side is provided with double windings, and the two windings are connected in series or in parallel for use according to field test conditions. Aiming at the current requirements of cable voltage withstanding and transformer partial discharge voltage withstanding, modification is carried out on the basis of original exciting transformer equipment, so that the equipment voltage withstanding test of different equipment capacities can be met, and the workload of personnel wiring during the test can be remarkably reduced.

Description

Technical Field

[0001] The invention relates to the field of power test transformers, and in particular to an embedded non-excitation voltage-regulating broadband test transformer. Background Art

[0002] The excitation transformer plays a role in initially increasing the input power supply voltage in the series resonant high-voltage test. Its capacity needs to be greater than the entire test capacity, because the test transformer capacities of combined electrical appliances, power cables, and transformers are different. Among the existing test transformers, there is no transformer that can meet the combined electrical appliance withstand voltage, power cable withstand voltage, and transformer partial discharge test. Therefore, it is necessary to design a variable frequency AC withstand voltage test transformer that meets different working conditions. Summary of the invention

[0003] In view of the above problems, the present invention provides a test transformer which can be used in electrical tests for transformer partial discharge withstand voltage, short length cable withstand voltage, and transformer partial discharge, and can conveniently and efficiently meet the test requirements.

[0004] In order to achieve the above object, the present invention provides an embedded no-excitation voltage-regulating wide-band test transformer, which comprises: a high-voltage side coil capable of on-load voltage regulation and a low-voltage side coil capable of gear adjustment;

[0005] The high-voltage side coil of the test transformer is provided with 7 switches, namely X1, X2, X3, X4, X5, X6 and X7: when the switch X1 is selected, the voltage of the high-voltage side coil is 40kV, when the switch X2 is selected, the voltage of the high-voltage side coil is 35kV, when the switch X3 is selected, the voltage of the high-voltage side coil is 30kV, when the switch X4 is selected, the voltage of the high-voltage side coil is 25kV, when the switch X5 is selected, the voltage of the high-voltage side coil is 20kV, when the switch X6 is selected, the voltage of the high-voltage side coil is 15kV, and when the switch X7 is selected, the voltage of the high-voltage side coil is 10kV;

[0006] The low-voltage side coil of the test transformer is provided with 4 terminals and 2 gears, namely a1, a2, x1, and x2: when gear 1 is selected, that is, terminal a1 is connected to terminal a2 and terminal x1 is connected to terminal x2, the voltage of the low-voltage side coil is 0.7kV; when gear 2 is selected, that is, when terminals a1, x1, a2, and x2 are connected in sequence, the voltage of the low-voltage side coil is 0.35kV.

[0007] Preferably, the operating frequency is 100 Hz.

[0008] In a preferred embodiment, the test capacity can reach 50 kVA and the test frequency is in the range of 40 to 300 Hz.

[0009] The beneficial effects of the present invention are as follows: the present invention can simultaneously meet the requirements of the series resonance partial discharge test and has less wiring workload during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the voltage regulation wiring of the broadband test transformer of the present invention;

[0011] Figure 2 It is the wiring diagram of the broadband series resonance withstand voltage test of the present invention;

[0012] Figure 3 This is a flow chart of the voltage regulation process of the AI ​​control system of the present invention;

[0013] Figure 4 It is a schematic diagram of the regulating voltage range of the test transformer of the present invention. DETAILED DESCRIPTION

[0014] Embodiment 1:

[0015] The broadband test transformer based on on-load voltage regulation of the present invention will complete the voltage resistance tests such as cable withstand voltage, combined electrical withstand voltage, transformer partial discharge, etc., and perform gear switching according to the different capacities required for the test. In addition, the test transformer has an intelligent on-load voltage regulation function, which makes the withstand voltage range of the test transformer wider and shortens the withstand voltage time, avoiding the test personnel from frequently changing the wiring because the optimal resonance state has not been reached.

[0016] According to the law of electromagnetic induction Where Φ=Φ m sinωt, substitute into the above formula ω=2πf,E=-nΦ m 2πfcosωt.

[0017] So the valid values ​​are:

[0018] Where E is the induced potential, f is the frequency, N is the number of winding turns, and Φm is the main magnetic flux of the core. Applying more than 2 times the rated voltage to the transformer will inevitably lead to serious saturation of the core, the main magnetic flux Φm will increase by ΔΦm, and the excitation current i will increase sharply, causing the transformer to heat up and burn. In order to make the core unsaturated when applying more than 2 times the rated voltage to the transformer, the operating frequency of the transformer is designed to be 100Hz.

[0019] The test capacity of the broadband test transformer can reach 50kVA, and the test frequency is in the range of 40 to 300Hz. In addition, during the voltage boosting process, the transformer monitors the voltage, current, and phase of the excitation transformer in real time, further calculates the quality factor Q value of the resonant circuit of the circuit, and combines the AI ​​control system to perform on-load voltage regulation on the primary side and gear adjustment on the secondary side, gradually making the circuit reach the optimal resonant state.

[0020] Figure 1 This is a description of the tapping of the on-load voltage regulator of the test transformer. The high-voltage side is X1, X2, X3, X4, X5, X6, and X7, a total of 7 selector switches. The low-voltage side is a double winding, and the two windings are used in series or parallel according to the on-site test conditions. The regulating voltage range of the test transformer is as follows: Figure 4 As shown. The high-voltage side coil of the test transformer is provided with 7 switches, namely X1, X2, X3, X4, X5, X6 and X7: when the switch X1 is selected, the voltage of the high-voltage side coil is 40kV, when the switch X2 is selected, the voltage of the high-voltage side coil is 35kV, when the switch X3 is selected, the voltage of the high-voltage side coil is 30kV, when the switch X4 is selected, the voltage of the high-voltage side coil is 25kV, when the switch X5 is selected, the voltage of the high-voltage side coil is 20kV, when the switch X6 is selected, the voltage of the high-voltage side coil is 15kV, and when the switch X7 is selected, the voltage of the high-voltage side coil is 10kV;

[0021] The low-voltage side coil of the test transformer is provided with 4 terminals, namely a1, a2, x1, and x2: when terminal a1 is connected to terminal a2 and terminal x1 is connected to terminal x2, the voltage of the low-voltage side coil is 0.7kV; when terminals a1, x1, a2, and x2 are connected in sequence, the voltage of the low-voltage side coil is 0.35kV.

[0022] The broadband series resonance partial discharge test wiring diagram is as attached. Figure 2 As shown, T is a wide-band on-load voltage-regulating excitation transformer, L is a compensating reactor, Cf is a capacitive voltage divider, and Cx is the test product. During the withstand voltage test, by continuously adjusting the frequency and transformer ratio, L and Cx are made to reach a series resonance state, so that the voltage value reaches the withstand voltage value of the test product.

[0023] The flow chart of intelligent voltage regulation of broadband test transformer is as follows Figure 3 As shown, first the line is subjected to withstand voltage. In the initial stage of withstand voltage, the resonant Q value of the circuit is calculated. During the first calculation, the criterion is not met, and the voltage, current, phase difference, frequency and other data are input into the AI ​​control system. After system analysis, on-load voltage regulation is performed once and gear switching is performed twice as needed. After the circuit loop parameters change, the Q value is further calculated and iterated continuously until the circuit reaches the optimal resonant state. In addition, during the boost process, the ground capacitance and corona loss will change, and the resonant Q value will also change. The AI ​​control system will adjust the voltage according to the monitored voltage, current, phase difference, frequency and other values.

[0024] The above-mentioned wide-band excitation transformer is modified on the basis of the original excitation transformer equipment to meet the current needs of cable withstand voltage and transformer partial discharge withstand voltage, so that it can not only meet the equipment withstand voltage test of different equipment capacities, but also significantly reduce the workload of personnel wiring during the test.

[0025] Embodiment 2:

[0026] An embedded non-excitation voltage-regulating wide-band test transformer comprises: a high-voltage side coil capable of on-load voltage regulation and a low-voltage side coil capable of gear adjustment;

[0027] The high-voltage side coil of the test transformer is provided with 7 switches, namely X1, X2, X3, X4, X5, X6 and X7: when the switch X1 is selected, the voltage of the high-voltage side coil is 40kV, when the switch X2 is selected, the voltage of the high-voltage side coil is 35kV, when the switch X3 is selected, the voltage of the high-voltage side coil is 30kV, when the switch X4 is selected, the voltage of the high-voltage side coil is 25kV, when the switch X5 is selected, the voltage of the high-voltage side coil is 20kV, when the switch X6 is selected, the voltage of the high-voltage side coil is 15kV, and when the switch X7 is selected, the voltage of the high-voltage side coil is 10kV;

[0028] The low-voltage side coil of the test transformer is provided with 4 terminals and 2 gears, namely a1, a2, x1, and x2: when gear 1 is selected, that is, terminal a1 is connected to terminal a2 and terminal x1 is connected to terminal x2, the voltage of the low-voltage side coil is 0.7kV; when gear 2 is selected, that is, when terminals a1, x1, a2, and x2 are connected in sequence, the voltage of the low-voltage side coil is 0.35kV.

[0029] Its operating frequency is 100Hz.

[0030] Its test capacity can reach 50kVA, and the test frequency is in the range of 40 to 300Hz.

[0031] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An embedded non-excitation voltage-regulating broadband test transformer, characterized in that: It includes: The high-voltage side coil can be used for on-load voltage regulation and the low-voltage side coil can be used for gear adjustment; The high-voltage side coil of the test transformer is provided with 7 switches, namely X1, X2, X3, X4, X5, X6 and X7: when the switch X1 is selected, the voltage of the high-voltage side coil is 40kV, when the switch X2 is selected, the voltage of the high-voltage side coil is 35kV, when the switch X3 is selected, the voltage of the high-voltage side coil is 30kV, when the switch X4 is selected, the voltage of the high-voltage side coil is 25kV, when the switch X5 is selected, the voltage of the high-voltage side coil is 20kV, when the switch X6 is selected, the voltage of the high-voltage side coil is 15kV, and when the switch X7 is selected, the voltage of the high-voltage side coil is 10kV; The low-voltage side coil of the test transformer is provided with 4 terminals and 2 gears, namely a1, a2, x1, and x2: when gear 1 is selected, that is, terminal a1 is connected to terminal a2 and terminal x1 is connected to terminal x2, the voltage of the low-voltage side coil is 0.7kV; when gear 2 is selected, that is, when terminals a1, x1, a2, and x2 are connected in sequence, the voltage of the low-voltage side coil is 0.35kV.

2. According to claim 1, the embedded non-excitation voltage-regulating broadband test transformer is characterized in that: Its operating frequency is 100Hz.

3. The embedded no-excitation voltage-regulating broadband test transformer according to claim 1 is characterized in that: Its test capacity can reach 50kVA, and the test frequency is in the range of 40 to 300Hz.

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