Energy storage oscillation online demagnetization device and system

Abstract

The invention provides an energy storage oscillation online demagnetization device and system, and relates to the technical field of transformer demagnetization. The on-line demagnetizing device comprises a power supply module and an energy storage capacitor, one end of the energy-storage capacitor is connected with the transformer maintenance grounding knife-switch, and the other end is connected with the ground; the one-way transformer is connected with the ground and the transformer maintenance grounding knife-switch. When the transformer maintenance grounding switch is not switched on, the power supply module charges the energy storage capacitor; when a transformer maintenance grounding knife switch is switched on, the energy storage capacitor, the excitation resistor of the one-way transformer and the iron core inductor form an RLC energy storage oscillation circuit. The RLC energy storage oscillation circuit generates damped oscillation current; and the unidirectional transformer is demagnetized by the damped oscillation current. The method is used for eliminating residual magnetism before transformer testing or switching on, and the time cost of transformer iron core demagnetization can be reduced.

Description

Technical Field

[0001] The present disclosure relates to the technical field of transformer demagnetization, and more specifically, to an energy storage oscillation online demagnetization device and system. Background Art

[0002] As one of the key components of the power transmission and distribution system, the stable working state of the transformer is crucial to the stability and reliability of the power grid. After the transformer is shut down or various test operations, residual magnetism will remain inside the core due to the hysteresis characteristics of ferromagnetic materials. When residual magnetism exists, the transformer may cause core saturation and generate excitation surge current when it is connected to the power grid without load. Its amplitude is usually 6 to 8 times the rated current. If it is not handled, it may have many adverse effects on the relay protection device and primary equipment of the power transformer, seriously affecting the safety, stability and efficient operation of the power system. Therefore, before testing or closing the transformer, it is necessary to eliminate the residual magnetism of the transformer to ensure that the transformer core is in a state without residual magnetism.

[0003] There have been some studies on strategies for eliminating residual magnetism in large transformers. The IEEE standard recommends two methods of demagnetization: the power frequency demagnetization method with gradually reduced voltage amplitude and the bipolar pulse demagnetization method with gradually reduced pulse width.

[0004] The current demagnetization technology mainly includes two methods: constant frequency variable amplitude and variable frequency constant amplitude. The amplitude and frequency of the excitation are controlled by power electronic switches to build a continuous excitation with gradually attenuated amplitude-second product. However, this demagnetization method has the problem that the control frequency of the electronic switch cannot be adjusted and the excitation amplitude cannot be changed, which makes the time cost of demagnetization always high. Summary of the invention

[0005] In view of this, the present disclosure provides an energy storage oscillation online demagnetization device and system.

[0006] One aspect of the present disclosure provides an energy storage oscillation online demagnetization device, comprising: a power module and an energy storage capacitor; one end of the energy storage capacitor is connected to a transformer maintenance ground knife, and the other end is connected to the earth; a unidirectional transformer is respectively connected to the earth and the transformer maintenance ground knife;

[0007] When the transformer maintenance ground switch is not closed, the power module charges the energy storage capacitor;

[0008] When the transformer maintenance ground switch is closed, the energy storage capacitor, the exciting resistor and the core inductance of the unidirectional transformer form an RLC energy storage oscillation circuit; the RLC energy storage oscillation circuit generates a damped oscillating current; the damped oscillating current demagnetizes the unidirectional transformer.

[0009] According to an embodiment of the present disclosure, the power module includes a charging unit and a switch control unit; the charging unit and the energy storage capacitor form a charging circuit; and the switch control unit is arranged on the charging circuit.

[0010] According to an embodiment of the present disclosure, the switch control unit includes a control module and a relay connected to the control module; the control module generates a switch signal according to a preset rule; and the switch signal controls the opening and closing of the relay.

[0011] According to an embodiment of the present disclosure, the charging unit is a voltage doubler rectifier circuit.

[0012] According to an embodiment of the present disclosure, the voltage doubler rectifier circuit includes an AC power supply module, a first rectifier unit and at least one second rectifier unit;

[0013] The first rectifying unit comprises a diode and a rectifying capacitor connected in series with the positive electrode of the diode; the negative electrode of the diode is grounded; one end of the AC power supply module is grounded, and the other end is connected to the rectifying capacitor;

[0014] The second rectifying unit includes a first rectifying capacitor, a second rectifying capacitor, a first diode and a second diode; one end of the first rectifying capacitor is connected to the positive electrode of the first diode and the negative electrode of the second diode; the negative electrode of the first diode is connected to one end of the second rectifying capacitor; the other end of the second rectifying capacitor is connected to the positive electrode of the second diode; the other end of the first rectifying capacitor serves as the first output end of the second rectifying unit, and the negative electrode of the first diode serves as the second output end of the second rectifying unit;

[0015] When the number of the second rectifying unit is 1, the first output end is connected to the cathode of the diode; the second output end is connected to the anode of the diode;

[0016] When the number of the second rectifier units is greater than one, the first output end of the first second rectifier unit is connected to the cathode of the diode, and the second output end is connected to the anode of the diode; the first output end of the i+1th second rectifier unit is connected to the cathode of the second diode of the i-th second rectifier unit, and the second output end is connected to the anode of the second diode of the i-th second rectifier unit; i is a positive integer greater than or equal to 1; i is less than N, and N is the number of second rectifier units.

[0017] According to an embodiment of the present disclosure, when the voltage doubler rectifier circuit is an even-numbered voltage doubler rectifier circuit, the cathode of the diode is used as the first voltage output terminal of the voltage doubler rectifier circuit, and the cathode of the second diode of the Nth second rectifier unit is used as the second voltage output terminal of the voltage doubler rectifier circuit;

[0018] The first voltage output terminal is connected to one end of the energy storage capacitor; the second voltage output terminal is connected to the other end of the energy storage capacitor.

[0019] According to an embodiment of the present disclosure, when the voltage doubler rectifier circuit is an odd-numbered voltage doubler rectifier circuit, the connection point between the rectifier capacitor and the AC power supply module is used as the first voltage output end of the voltage doubler rectifier circuit, and the positive electrode of the second diode of the Nth second rectifier unit is used as the second voltage output end of the voltage doubler rectifier circuit;

[0020] The first voltage output terminal is connected to one end of the energy storage capacitor; the second voltage output terminal is connected to the other end of the energy storage capacitor.

[0021] According to an embodiment of the present disclosure, in the RLC energy storage oscillation circuit, the capacitance value of the energy storage capacitor should satisfy the following range:

[0022] ;

[0023] Among them, L leak is the leakage inductance of the transformer when it is saturated; L m It is the core magnetizing inductance of the transformer in the no-load state; is the core magnetizing resistance of the transformer in the no-load state; C is the capacitance value of the energy storage capacitor.

[0024] Another aspect of the present disclosure provides a system based on an energy storage oscillation online demagnetization device, comprising: a unidirectional transformer, a transformer maintenance ground knife, a transmission line, a power grid, and the energy storage oscillation online demagnetization device according to an embodiment of the present disclosure; the energy storage oscillation online demagnetization device comprises a power module and an energy storage capacitor;

[0025] The transformer maintenance ground knife is connected to the earth through the energy storage capacitor; the unidirectional transformer is connected to the power grid and the transformer maintenance ground knife respectively through the transmission line;

[0026] When the transformer maintenance ground switch is not closed, the power module charges the energy storage capacitor;

[0027] When the transformer maintenance ground switch is closed, the energy storage capacitor, the exciting resistor and the core inductance of the unidirectional transformer form an RLC energy storage oscillation circuit; the RLC energy storage oscillation circuit generates a damped oscillating current; the damped oscillating current demagnetizes the unidirectional transformer.

[0028] According to an embodiment of the present disclosure, the system based on the energy storage oscillation online demagnetization device further includes a circuit breaker and a line detection grounding knife;

[0029] The circuit breaker is arranged on the transmission line; one end of the circuit breaker is respectively connected to the transformer maintenance grounding knife and the unidirectional transformer, and the other end is respectively connected to one end of the line detection grounding knife and the power grid; the other end of the line detection grounding knife is connected to the earth.

[0030] According to the embodiments of the present disclosure, since the energy storage oscillation online demagnetization device is connected in series between the transformer maintenance ground knife and the earth, before the transformer detection ground knife is closed, the power module of the energy storage oscillation online demagnetization device charges the energy storage capacitor. When the transformer maintenance ground knife is closed, the energy storage capacitor of the energy storage oscillation online demagnetization device, the excitation resistor and the core inductance of the unidirectional transformer form an RLC energy storage oscillation circuit; the RLC energy storage oscillation circuit generates a decaying oscillating current; the decaying oscillating current demagnetizes the unidirectional transformer, and the energy storage capacitor C provides the decaying oscillation current to the transformer, so that the transformer achieves the purpose of demagnetization, simplifies the operations required to demagnetize the transformer, and reduces the time required for demagnetization, so as to at least partially overcome the technical problem that the time cost of demagnetization is always high, thereby achieving the technical effect of improving the demagnetization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0032] Figure 1 The schematic diagram of the circuit of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is shown;

[0033] Figure 2 The working flow chart of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is schematically shown;

[0034] Figure 3 The schematic diagram shows an odd-number voltage multiplication rectifier power supply module of the energy storage oscillation online demagnetization device according to an embodiment of the present disclosure;

[0035] Figure 4 The even-voltage-multiplying rectifier power supply module of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is schematically shown;

[0036] Figure 5 A circuit diagram of an energy storage oscillation online demagnetization device according to an embodiment of the present disclosure is schematically shown;

[0037] Figure 6 A power system connection diagram of an energy storage oscillation online demagnetization device according to an embodiment of the present disclosure is schematically shown;

[0038] Figure 7 A schematic diagram of the control of the energy storage oscillation online demagnetization device according to an embodiment of the present disclosure is shown;

[0039] Figure 8 The output voltage waveform diagram of the five-times-voltage rectifier power supply module of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is schematically shown;

[0040] Fig. 9 The current waveform diagram generated by the energy storage oscillation online demagnetization device in the core inductance L according to the embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0041] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0042] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0043] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0044] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0045] In the embodiments of the present disclosure, the collection, updating, analysis, processing, use, transmission, provision, disclosure, storage, etc. of the data involved (for example, including but not limited to user personal information) are in compliance with the provisions of relevant laws and regulations, are used for legitimate purposes, and do not violate public order and good morals. In particular, necessary measures are taken for user personal information to prevent illegal access to user personal information data and maintain the security of user personal information, network security, and national security.

[0046] In the embodiments of the present disclosure, the user's authorization or consent is obtained before obtaining or collecting the user's personal information.

[0047] An embodiment of the present disclosure provides an energy storage oscillation online demagnetization device, which includes a power module and an energy storage capacitor; one end of the energy storage capacitor is connected to a transformer maintenance ground knife, and the other end is connected to the earth; a unidirectional transformer is respectively connected to the earth and the transformer maintenance ground knife.

[0048] When the transformer maintenance grounding knife is not closed, the power module charges the energy storage capacitor; when the transformer maintenance grounding knife is closed, the energy storage capacitor, the excitation resistance of the unidirectional transformer and the core inductance form an RLC energy storage oscillation circuit; the RLC energy storage oscillation circuit generates a damped oscillating current; the damped oscillating current demagnetizes the unidirectional transformer. Among them, the energy storage capacitor C is used to demagnetize the transformer core by providing an oscillating voltage to the transformer; among them, the energy storage capacitor C is determined according to the core inductance L, and its value should make the equivalent circuit composed of R, L, and C in an underdamped state.

[0049] According to an embodiment of the present disclosure, the power module includes a charging unit and a switch control unit; the charging unit and the energy storage capacitor form a charging circuit; the switch control unit is arranged on the charging circuit. The switch control unit includes a control module and a relay connected to the control module; the control module generates a switch signal according to a preset rule; the switch signal controls the opening and closing of the relay.

[0050] According to an embodiment of the present disclosure, the charging unit is a voltage doubling rectifier circuit. The voltage doubling rectifier circuit includes an AC power module, a first rectifier unit and at least one second rectifier unit; wherein the first rectifier unit includes a diode and a rectifier capacitor connected in series with the positive electrode of the diode; the negative electrode of the diode is grounded; one end of the AC power module is grounded, and the other end is connected to the rectifier capacitor; the second rectifier unit includes a first rectifier capacitor, a second rectifier capacitor, a first diode and a second diode; one end of the first rectifier capacitor is connected to the positive electrode of the first diode and the negative electrode of the second diode; the negative electrode of the first diode is connected to one end of the second rectifier capacitor; the other end of the second rectifier capacitor is connected to the positive electrode of the second diode; the other end of the first rectifier capacitor serves as the first output end of the second rectifier unit, and the negative electrode of the first diode serves as the second output end of the second rectifier unit.

[0051] When the number of second rectifier units is 1, the first output end is connected to the cathode of the diode; the second output end is connected to the anode of the diode; when the number of second rectifier units is greater than 1, the first output end of the first second rectifier unit is connected to the cathode of the diode, and the second output end is connected to the anode of the diode; the first output end of the i+1th second rectifier unit is connected to the cathode of the second diode of the ith second rectifier unit, and the second output end is connected to the anode of the second diode of the ith second rectifier unit; i is a positive integer greater than or equal to 1; i is less than N, and N is the number of second rectifier units.

[0052] According to an embodiment of the present disclosure, the voltage doubler rectifier circuit is divided into an odd-number voltage doubler rectifier circuit and an even-number voltage doubler rectifier circuit.

[0053] When the voltage doubler rectifier circuit is an even-numbered voltage doubler rectifier circuit, the cathode of the diode is used as the first voltage output terminal of the voltage doubler rectifier circuit, and the cathode of the second diode of the Nth second rectifier unit is used as the second voltage output terminal of the voltage doubler rectifier circuit; the first voltage output terminal is connected to one end of the energy storage capacitor; and the second voltage output terminal is connected to the other end of the energy storage capacitor.

[0054] When the voltage doubler rectifier circuit is an odd-numbered voltage doubler rectifier circuit, the connection point between the rectifier capacitor and the AC power supply module is used as the first voltage output end of the voltage doubler rectifier circuit, and the positive electrode of the second diode of the Nth second rectifier unit is used as the second voltage output end of the voltage doubler rectifier circuit; the first voltage output end is connected to one end of the energy storage capacitor; and the second voltage output end is connected to the other end of the energy storage capacitor.

[0055] According to an embodiment of the present disclosure, in the RLC energy storage oscillation circuit, the capacitance value of the energy storage capacitor should satisfy the following range:

[0056] .

[0057] Among them, L leak is the leakage inductance of the transformer when it is saturated; L m It is the core magnetizing inductance of the transformer in the no-load state; is the core magnetizing resistance of the transformer in the no-load state; C is the capacitance value of the energy storage capacitor.

[0058] According to an embodiment of the present disclosure, the working process of the energy storage oscillation online demagnetization device is as follows:

[0059] First, when the winding voltage and loop current change gradually, the core magnetic flux increases rapidly, causing the core magnetic field to gradually increase until it reaches saturation. Second, when the winding voltage and loop current change rapidly, the core magnetic flux changes slowly. At this time, the electric field of the capacitor reverses its polarity, and the excess energy is fed back and stored in the capacitor. Then, similar to the first stage, the core magnetic field changes significantly, accompanied by a reversal of the polarity of the core magnetic field. Finally, similar to the second stage, the electric field of the capacitor reverses its polarity again.

[0060] The embodiment of the present disclosure also includes a system based on an energy storage oscillation online demagnetization device, the system includes a unidirectional transformer, a transformer maintenance ground knife, a transmission line, a power grid, and an energy storage oscillation online demagnetization device of the embodiment of the present disclosure. The energy storage oscillation online demagnetization device includes a power module and an energy storage capacitor. The transformer maintenance ground knife is connected to the earth through the energy storage capacitor; the unidirectional transformer is connected to the power grid and the transformer maintenance ground knife respectively through the transmission line.

[0061] When the transformer maintenance ground switch is not closed, the power module charges the energy storage capacitor; when the transformer maintenance ground switch is closed, the energy storage capacitor, the excitation resistor and the core inductance of the unidirectional transformer form an RLC energy storage oscillation circuit; the RLC energy storage oscillation circuit generates a decaying oscillating current; the decaying oscillating current demagnetizes the unidirectional transformer.

[0062] According to an embodiment of the present disclosure, the system also includes a circuit breaker and a line detection grounding knife; the circuit breaker is arranged on the transmission line; one end of the circuit breaker is respectively connected to the transformer maintenance grounding knife and the unidirectional transformer, and the other end is respectively connected to one end of the line detection grounding knife and the power grid; the other end of the line detection grounding knife is connected to the earth.

[0063] Figure 1 The schematic diagram of the circuit of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is shown. Figure 1 As shown, the embodiment of the present disclosure includes: an energy storage capacitor C, an exciting resistor R, and an iron core inductor L. The power module charges the energy storage capacitor C, the energy storage capacitor C stores energy, and then supplies power to the transformer iron core inductor L, wherein R, L, and C must meet the underdamping condition, and the present invention realizes the demagnetization operation through LC oscillation.

[0064] Figure 2 The working flow chart of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is schematically shown; Figure 2 As shown, the process of realizing demagnetization of the energy storage oscillation online demagnetization device of the embodiment of the present disclosure includes:

[0065] S1, input the program to the control board to control the on and off of the relay to complete the charging process of the energy storage capacitor.

[0066] S2, the transformer maintenance ground switch is closed to form an RLC oscillation circuit, realize the discharge process of the capacitor, and generate a damped oscillating current.

[0067] S3, according to Faraday's law of electromagnetic induction, makes the magnetic flux of the iron core gradually decrease, thereby achieving the effect of demagnetization.

[0068] Figure 3 The odd-number voltage-multiplier rectifier power supply module of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is schematically shown; Figure 3 As shown, the working principle of the odd-voltage multiplier rectifier power supply module of the embodiment of the present invention is: in the positive half cycle of the AC power supply, VD1 is turned on, and C1 starts to charge to a value close to the peak value Um of the input voltage; when the AC power supply is in the negative half cycle, VD2 is turned on, and VD1 is turned off. At this time, the voltage on C1 is superimposed on the power supply voltage, and C2 starts to charge to a value close to 2Um; in the next positive half cycle, VD3 is turned on, and VD2 is turned off, and the power supply voltage, the capacitor C1 voltage, and the capacitor C2 voltage are superimposed on each other. Because the voltage direction of the capacitor C1 is reversed, one Um will be offset in the end, so that the capacitor C3 is fully charged, and the voltage across it is 2Um. Similarly, the voltage across capacitors C3, C4, and C5 is also 2Um. Therefore, the voltage across C1, C3, and C5 is 5Um. Similarly, the voltage across Cn-1 and Cn is also 2Um. The output voltage U0 at the output end is the sum of the voltages across C1, C3, C5, ..., Cn-1 and Cn. The output voltage U0 is n times Um. Therefore, the output voltage U0 is n times DC, where n is an odd number.

[0069] Figure 4 The even-voltage-multiplying rectifier power supply module of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is schematically shown; Figure 4 As shown, the working principle of the even-number voltage-multiplying rectifier power supply module of the embodiment of the present disclosure is similar to Figure 3 The working principle of the odd-numbered voltage rectifier power module is the same, which will not be repeated here. The output voltage U0 is n-1 times Um, so the output voltage U0 is n-1 times the voltage DC, and n is an odd number. The voltage output terminal of the even-numbered voltage rectifier power module is different from the voltage output terminal of the odd-numbered voltage rectifier power module.

[0070] Figure 5 The circuit diagram of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is schematically shown; Figure 5 As shown, according to an embodiment of the present disclosure, the energy storage oscillation online demagnetization device includes: a multi-voltage rectifier circuit of a power module, a relay, a transformer maintenance ground knife, an energy storage capacitor, an exciting resistor, and an iron core inductor. The power module first charges the energy storage capacitor C, and after the voltage across the energy storage capacitor C reaches a threshold, the energy storage capacitor C discharges the iron core inductor L.

[0071] Figure 6 The power system connection diagram of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is schematically shown; Figure 6 As shown, the power system connection diagram of the embodiment of the present disclosure includes: a circuit breaker, a transformer maintenance ground knife, an energy storage oscillation online demagnetization device, a single-phase transformer, a line maintenance ground knife, and a grid-side switch. The energy storage oscillation online demagnetization device is connected in series between the transformer maintenance ground knife and the earth. Before the transformer maintenance ground knife is closed, when the voltage-doubling rectifier circuit is a five-times-voltage rectifier circuit and 220V AC is input, the power module charges the energy storage capacitor C to 1550V. The simulation sets the circuit breaker opening time to 0.5s, the grid-side switch opening time to 1.5s, the line maintenance ground knife closing time to 2.0s, and the transformer maintenance ground knife closing time to 2.5s, and obtains the current simulation result of the RLC loop.

[0072] Figure 7 The control schematic diagram of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is schematically shown; Figure 7 As shown, the control board first sends a control signal to control relay KV1 to turn on and charge the energy storage capacitor C. When the energy storage capacitor C reaches the required capacitor voltage, the control board sends a control signal to control KV1 to turn off, the transformer maintenance ground knife is turned on, and the energy storage capacitor C forms an oscillation circuit with the excitation resistance and excitation inductance in the tested transformer for demagnetization. Hardware design is carried out based on the simulation circuit and simulation results.

[0073] The energy storage oscillation online demagnetization device includes a solid-state relay, a multi-voltage rectifier capacitor, a diode, an energy storage capacitor C, and an exciting resistor R. The multi-voltage rectifier capacitor and the diode constitute a multi-stage voltage multiplier rectifier module, which amplifies and rectifies the peak value of the input AC voltage into multiple DC. The control board sends a control signal, and the relay is controlled to be turned on and off through the control module to realize the charging and discharging of the energy storage capacitor C; first, the energy storage capacitor C is charged, and then the energy storage capacitor C in the RLC second-order oscillation circuit is used to discharge the transformer core inductance L, and the RLC second-order oscillation circuit is adjusted to be in an underdamped state, and a voltage and current of attenuated oscillation are generated in the demagnetization coil, so that the core of the transformer is demagnetized. Specifically, the energy storage capacitor is electrically connected to the transformer, so that when the energy storage capacitor supplies power to the transformer, the electric field energy of the energy storage capacitor is converted into the magnetic field energy of the core of the transformer, and after the magnetic field energy of the core is fully stored, the energy storage capacitor receives the electric field energy formed by the magnetic field energy of the core, thereby forming the oscillation voltage.

[0074] Among them, the oscillation frequency of the oscillating current is determined by the energy storage capacitor C and the core inductance L. According to the oscillation angular frequency In the underdamped state, even if the R value increases, the frequency of the oscillating current will not change. The oscillation frequency only depends on the ratio of L and C, and has nothing to do with the size of the resistance R.

[0075] Taking the five-fold voltage rectifier power module generating 1550V voltage as an example, the five-fold voltage rectifier power module inputs 220V AC power and outputs about 1550V DC power. The energy storage module is an energy storage capacitor. The energy storage capacitor C is selected to be 2mF, and four 0.5mF ​​capacitors are connected in parallel. Input the program into the control board, and the control module outputs a control signal to control the on and off of the relay. First, the control signal turns on the relay KV1 to charge the energy storage capacitor C. When the energy storage capacitor C is charged to a certain value, the relay is controlled to be turned off. When the transformer maintenance ground knife is closed, an RLC energy storage oscillation equivalent circuit is formed, and the energy storage oscillation discharges the energy storage capacitor C in the online demagnetization device to the transformer core inductance L.

[0076] Figure 8 The output voltage waveform of the five-fold voltage rectifier power module of the energy storage oscillation online demagnetization device according to the embodiment of the present disclosure is schematically shown; Figure 8 As shown in the figure, after the 220V AC passes through the multi-voltage rectifier circuit, it outputs a voltage five times the peak value (about 1550V).

[0077] Fig. 9 The current waveform diagram generated by the energy storage oscillation online demagnetization device in the core inductance L according to the embodiment of the present disclosure is schematically shown. Fig. 9 As shown, the energy storage capacitor C, the core inductor L, and the exciting resistor R form an RLC oscillation circuit. When the RLC meets the underdamped state condition, a damped oscillating current will be generated in the loop, thereby achieving a demagnetization effect.

[0078] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. An energy storage oscillation online demagnetization device, characterized in that: The online demagnetization device comprises a power module and an energy storage capacitor; one end of the energy storage capacitor is connected to the transformer maintenance ground knife, and the other end is connected to the earth; the unidirectional transformer is respectively connected to the earth and the transformer maintenance ground knife; When the transformer maintenance ground switch is not closed, the power module charges the energy storage capacitor; When the transformer maintenance ground switch is closed, the energy storage capacitor, the exciting resistor and the core inductance of the unidirectional transformer form an RLC energy storage oscillation circuit; the RLC energy storage oscillation circuit generates a damped oscillating current; the damped oscillating current demagnetizes the unidirectional transformer.

2. The energy storage oscillation online demagnetization device according to claim 1, characterized in that: The power supply module comprises a charging unit and a switch control unit; the charging unit and the energy storage capacitor form a charging circuit; the switch control unit is arranged on the charging circuit.

3. The energy storage oscillation online demagnetization device according to claim 2, characterized in that: The switch control unit includes a control module and a relay connected to the control module; the control module generates a switch signal according to a preset rule; and the switch signal controls the opening and closing of the relay.

4. The energy storage oscillation online demagnetization device according to claim 2, characterized in that: The charging unit is a voltage doubler rectifier circuit.

5. The energy storage oscillation online demagnetization device according to claim 4, characterized in that: The voltage doubler rectifier circuit comprises an AC power supply module, a first rectifier unit and at least one second rectifier unit; The first rectifying unit comprises a diode and a rectifying capacitor connected in series with the positive electrode of the diode; the negative electrode of the diode is grounded; one end of the AC power supply module is grounded, and the other end is connected to the rectifying capacitor; The second rectifying unit includes a first rectifying capacitor, a second rectifying capacitor, a first diode and a second diode; one end of the first rectifying capacitor is connected to the positive electrode of the first diode and the negative electrode of the second diode; the negative electrode of the first diode is connected to one end of the second rectifying capacitor; the other end of the second rectifying capacitor is connected to the positive electrode of the second diode; the other end of the first rectifying capacitor serves as the first output end of the second rectifying unit, and the negative electrode of the first diode serves as the second output end of the second rectifying unit; When the number of the second rectifying unit is 1, the first output end is connected to the cathode of the diode; the second output end is connected to the anode of the diode; When the number of the second rectifier units is greater than one, the first output end of the first second rectifier unit is connected to the cathode of the diode, and the second output end is connected to the anode of the diode; the first output end of the i+1th second rectifier unit is connected to the cathode of the second diode of the i-th second rectifier unit, and the second output end is connected to the anode of the second diode of the i-th second rectifier unit; i is a positive integer greater than or equal to 1; i is less than N, and N is the number of second rectifier units.

6. The energy storage oscillation online demagnetization device according to claim 5, characterized in that: When the voltage doubler rectifier circuit is an even-numbered voltage doubler rectifier circuit, the cathode of the diode is used as the first voltage output terminal of the voltage doubler rectifier circuit, and the cathode of the second diode of the Nth second rectifier unit is used as the second voltage output terminal of the voltage doubler rectifier circuit; The first voltage output terminal is connected to one end of the energy storage capacitor; the second voltage output terminal is connected to the other end of the energy storage capacitor.

7. The energy storage oscillation online demagnetization device according to claim 5, characterized in that: When the voltage doubler rectifier circuit is an odd-numbered voltage doubler rectifier circuit, the connection point between the rectifier capacitor and the AC power supply module is used as the first voltage output end of the voltage doubler rectifier circuit, and the positive electrode of the second diode of the Nth second rectifier unit is used as the second voltage output end of the voltage doubler rectifier circuit; The first voltage output terminal is connected to one end of the energy storage capacitor; the second voltage output terminal is connected to the other end of the energy storage capacitor.

8. The energy storage oscillation online demagnetization device according to claim 1, characterized in that: In the RLC energy storage oscillation circuit, the capacitance value of the energy storage capacitor should satisfy the following range: ； Among them, L leak is the leakage inductance of the transformer when it is saturated; L m It is the core magnetizing inductance of the transformer in the no-load state; is the core magnetizing resistance of the transformer in the no-load state; C is the capacitance value of the energy storage capacitor.

9. A system based on an energy storage oscillation online demagnetization device, characterized in that: The system comprises a unidirectional transformer, a transformer maintenance ground knife, a transmission line, a power grid and an energy storage oscillation online demagnetization device according to any one of claims 1 to 8; The energy storage oscillation online demagnetization device comprises a power supply module and an energy storage capacitor; The transformer maintenance ground knife is connected to the earth through the energy storage capacitor; the unidirectional transformer is connected to the power grid and the transformer maintenance ground knife respectively through the transmission line; When the transformer maintenance ground switch is not closed, the power module charges the energy storage capacitor; When the transformer maintenance ground switch is closed, the energy storage capacitor, the exciting resistor and the core inductance of the unidirectional transformer form an RLC energy storage oscillation circuit; the RLC energy storage oscillation circuit generates a damped oscillating current; the damped oscillating current demagnetizes the unidirectional transformer.

10. The system based on the energy storage oscillation online demagnetization device according to claim 9, characterized in that: The system also includes a circuit breaker and a line detection ground switch; The circuit breaker is arranged on the transmission line; one end of the circuit breaker is respectively connected to the transformer maintenance grounding knife and the unidirectional transformer, and the other end is respectively connected to one end of the line detection grounding knife and the power grid; the other end of the line detection grounding knife is connected to the earth.

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