Discharging degaussing circuit after direct current resistance test of distribution transformer

Abstract

The discharging degaussing circuit after the direct current resistance test of the distribution transformer comprises an inverter H bridge, a rechargeable storage battery and a voltage reduction feedback circuit, the inverter H bridge comprises an MOS tube Q1, an MOS tube Q2, an MOS tube Q3 and an MOS tube Q4, the source electrode of the MOS tube Q1 is connected with an alternating current output end, the source electrode of the MOS tube Q3 is connected with the other alternating current output end, the MOS tube Q1, the MOS tube Q2, the MOS tube Q3 and the MOS tube Q4 are respectively and externally connected with a direct current power supply through a control circuit, and the voltage reduction feedback circuit is connected with the voltage reduction feedback circuit. The drain electrode of the MOS tube Q1 and the drain electrode of the MOS tube Q3 are externally connected with a BOOST2 circuit, the source electrode of the MOS tube Q2 and the source electrode of the MOS tube Q4 are grounded, and the BOOST2 circuit is connected with the rechargeable storage battery through a voltage reduction feedback circuit. According to the utility model, a bidirectional energy feedback mode is adopted, direct current can be converted into alternating current for boosting to apply test voltage to the transformer, residual electricity on the transformer can be reduced and fed back to internal stored energy after test, the size is small, the weight is light, energy recovery can be realized, and the discharge speed is high.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic transformer demagnetization, and more specifically to a discharge demagnetization circuit after a direct resistance test of a distribution transformer. Background Art

[0002] As the core equipment of the power system, the transformer undertakes the functions of voltage conversion, energy transmission and power distribution. The DC resistance test of the transformer is one of the must-test items for the distribution transformer before leaving the factory, and generally the DC resistance value needs to be tested more than 5 times according to different tap positions.

[0003] After each DC resistance measurement, there will be electricity on the transformer. If it is not discharged, the test is unsafe and affects the test accuracy. Therefore, the DC resistance test of the transformer is an important test item in the semi-finished product test, finished product factory test, installation, handover test and preventive test of the power department. Through the test, the manufacturing defects of the transformer coil (such as improper material selection, missing strands, broken wires, and oxidation or looseness of welding and connection parts) and safety hazards after operation can be discovered in time.

[0004] When using a transformer DC resistance tester to measure the DC resistance of a transformer, a certain amount of DC power needs to be added to the transformer winding coil for each measurement. Therefore, a certain amount of energy is stored in the transformer winding coil during the measurement process, that is, a large amount of residual magnetism will remain on the transformer core. This may generate a large value and a long time of excitation inrush current when the equipment is put into operation, causing harm to the operation of the power grid.

[0005] At present, the demagnetization equipment in the prior art all performs demagnetization by selecting a demagnetization current. The demagnetization process is displayed in the form of a percentage of the demagnetization progress. The demagnetization time is relatively long. This discharge method will heat up the discharge resistor and the discharge is slow. If you want to discharge quickly, the size of the discharge resistor will be very large. Utility Model Content

[0006] The utility model provides a discharge demagnetization circuit for a distribution transformer after a direct resistance test, so as to solve the problems of heating of the discharge resistor, slow discharge and large volume of the discharge resistor in the existing discharge method.

[0007] According to one aspect of the utility model, a discharge demagnetization circuit after a direct resistance test of a distribution transformer is provided, comprising an inverter H-bridge, a rechargeable battery and a step-down feedback circuit, wherein the inverter H-bridge comprises a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3 and a MOS transistor Q4, wherein the source of the MOS transistor Q1 is connected to an AC output terminal, the source of the MOS transistor Q3 is connected to another AC output terminal, and the MOS transistor Q1, the MOS transistor Q2, the MOS transistor Q3 and the MOS transistor Q4 are respectively connected to an external DC power supply through a control circuit, the drain of the MOS transistor Q1 and the drain of the MOS transistor Q3 are externally connected to a BOOST2 circuit, the source of the MOS transistor Q2 and the source of the MOS transistor Q4 are grounded, the BOOST2 circuit is connected to the rechargeable battery through the step-down feedback circuit, and the AC output terminals are respectively externally connected to distribution transformers.

[0008] Preferably, based on the above scheme, the step-down feedback circuit includes an inductor L1, an inductor L2, a relay and a BOOST1 circuit, one end of the relay is connected to the BOOST2 circuit, and the other end thereof is connected to the inductor L1 through a thermistor, and the other end of the inductor L1 is connected to the BOOST1 circuit; one end of the inductor L2 is connected to the BOOST2 circuit, and the other end of the inductor L2 is connected to the BOOST1 circuit, and the rechargeable battery is connected to the inductor L1.

[0009] Preferably, based on the above solution, the MOS transistor Q1 , MOS transistor Q2 , MOS transistor Q3 and MOS transistor Q4 are all N-channel MOS transistors.

[0010] The utility model discloses a distribution transformer discharge demagnetization circuit after direct resistance test, which adopts a bidirectional energy feedback method, can not only apply the test voltage to the transformer by converting direct current into alternating current and boosting the voltage, but also can reduce the voltage of the residual electricity on the transformer and feed it back to the internal energy storage after the test, has a small size, light weight, can realize energy recovery, and has a fast discharge speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following is a brief introduction to the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0012] Figure 1 It is a circuit diagram of the step-down feedback circuit of the utility model;

[0013] Figure 2 The circuit diagram of the inverter H-bridge of the utility model; DETAILED DESCRIPTION

[0014] The following is a further detailed description of the specific implementation of the present invention in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0015] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections.

[0016] In order to simplify the drawings, only the parts related to the utility model are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0017] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0018] In the embodiments shown in the drawings, the directions (such as up, down, left, right, front and back) used to explain the structure and movement of the various components of the present invention are not absolute but relative. These descriptions are appropriate when the components are in the positions shown in the drawings. If the description of the positions of the components changes, the directions also change accordingly.

[0019] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0020] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the specific implementation methods of the utility model will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0021] See also Figure 1 , and combined with Figure 2As shown, a distribution transformer direct resistance test post-discharge demagnetization circuit of the utility model comprises an inverter H-bridge A1, a rechargeable battery and a step-down feedback circuit, the inverter H-bridge A1 comprises MOS tubes Q1, MOS tubes Q2, MOS tubes Q3 and MOS tubes Q4, the source of the MOS tube Q1 is connected to an AC output terminal TK8, the source of the MOS tube Q3 is connected to another AC output terminal TK9, and the MOS tubes Q1, MOS tubes Q2, MOS tubes Q3 and MOS tubes Q4 are respectively connected to an external DC power supply through a control circuit, the drain of the MOS tube Q1 and the drain of the MOS tube Q3 are externally connected to a BOOST2 circuit, the source of the MOS tube Q2 and the source of the MOS tube Q4 are grounded, the BOOST2 circuit is connected to the rechargeable battery through the step-down feedback circuit, and the AC output terminals (TK8 / TK9) are respectively externally connected to the distribution transformer.

[0022] The step-down feedback circuit includes an inductor L1, an inductor L2, a relay and a BOOST1 circuit. One end of the relay is connected to the BOOST2 circuit, and the other end is connected to the inductor L1 through the thermistor RT1. The other end of the inductor L1 is connected to the BOOST1 circuit. One end of the inductor L2 is connected to the BOOST2 circuit, and the other end of the inductor L2 is connected to the BOOST1 circuit. The rechargeable battery is connected to the inductor L1.

[0023] When demagnetizing, the DC power supply is used to output AC power through the inverter H-bridge A1 and applied to both sides of the distribution transformer to perform preliminary and rapid demagnetization of the transformer.

[0024] After demagnetization is completed, the residual voltage in the distribution transformer is fed back to the inverter H bridge A1, and then to the anti-reverse diode D4, BOOST2 inductor L2 through the BOOST1 circuit inductor L1, and then to the field effect tube Q4 (in parallel with Q3) for boosting, and the BOOST2 circuit voltage is obtained, and then fed back to the rechargeable battery through the relay and the current limiting thermistor RT1, and the current limiting of the BOOST1 inductor L1. Among them, the relay is controlled by the DSP to give a signal T1, and preferably, the MOS tube Q1, MOS tube Q2, MOS tube Q3 and MOS tube Q4 are all N-channel MOS tubes.

[0025] The utility model discloses a distribution transformer discharge demagnetization circuit after direct resistance test, which adopts a bidirectional energy feedback method, can not only apply the test voltage to the transformer by converting direct current into alternating current and boosting the voltage, but also can reduce the voltage of the residual electricity on the transformer and feed it back to the internal energy storage after the test, has a small size, light weight, can realize energy recovery, and has a fast discharge speed.

[0026] Finally, the method of this application is only a preferred implementation scheme and is not intended to limit the protection scope of the utility model. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A discharge degaussing circuit for a distribution transformer after a direct resistance test, characterized in that: The invention comprises an inverter H-bridge, a rechargeable battery and a step-down feedback circuit. The inverter H-bridge comprises a MOS tube Q1, a MOS tube Q2, a MOS tube Q3 and a MOS tube Q4. The source of the MOS tube Q1 is connected to an AC output terminal, the source of the MOS tube Q3 is connected to another AC output terminal, and the MOS tubes Q1, Q2, Q3 and Q4 are respectively connected to an external DC power supply through a control circuit. The drain of the MOS tube Q1 and the drain of the MOS tube Q3 are externally connected to a BOOST2 circuit, the source of the MOS tube Q2 and the source of the MOS tube Q4 are grounded, the BOOST2 circuit is connected to the rechargeable battery through the step-down feedback circuit, and the AC output terminals are respectively externally connected to a distribution transformer.

2. A distribution transformer direct resistance test post-discharge degaussing circuit as claimed in claim 1, characterized in that: The step-down feedback circuit includes an inductor L1, an inductor L2, a relay and a BOOST1 circuit. One end of the relay is connected to the BOOST2 circuit, and the other end is connected to the inductor L1 through a thermistor. The other end of the inductor L1 is connected to the BOOST1 circuit; one end of the inductor L2 is connected to the BOOST2 circuit, and the other end of the inductor L2 is connected to the BOOST1 circuit. The rechargeable battery is connected to the inductor L1.

3. A discharge degaussing circuit after direct resistance test of distribution transformer as claimed in claim 1, characterized in that: The MOS transistor Q1 , MOS transistor Q2 , MOS transistor Q3 and MOS transistor Q4 are all N-channel MOS transistors.

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