Pre-magnetizing control device and circuit

Abstract

The invention relates to the technical field of transformers, in particular to a pre-magnetizing control device and circuit. The pre-magnetizing control device comprises a microcontroller, a signal acquisition circuit, a relay output circuit and a crystal oscillator circuit, the signal acquisition circuit, the relay output circuit and the crystal oscillator circuit are respectively connected with the microcontroller, and the signal acquisition circuit is used for acquiring a trigger signal and a control signal generated by system operation. The relay output circuit is used for controlling starting and stopping of pre-magnetizing, and the crystal oscillator circuit is used for controlling the time of pre-magnetizing. The pre-magnetizing control device can effectively control the closing magnetizing inrush current of the transformer and abandon some easily-damaged elements, can meet various pre-magnetizing requirements, and is high in universality.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and more specifically, to a pre-magnetization control device and circuit. Background Art

[0002] With the continuous development of industrial electrical technology, the capacity of transformers used in industrial power engineering has also increased. When a large-capacity transformer is connected to the power grid, its excitation surge current can be more than ten times the rated current, which brings a huge impact to the front-end circuit breaker and the power grid. In order to reduce the impact of this excitation surge current, one of the most effective methods is to pre-magnetize the transformer before connecting it to the power grid.

[0003] Specifically, the traditional method is to use a transformer with the same transformation ratio as the large transformer but much smaller capacity, connect its secondary side to the secondary side of the large transformer, and connect the primary side to the power grid (such as Figure 1 As shown in the figure, before the large transformer is closed, power is first supplied to the small transformer to pre-magnetize the large transformer. After the magnetization is completed, the large transformer is closed. At this time, the surge current of the large transformer will drop significantly, thereby reducing the impact on the front-end circuit breaker and the power grid. After the large transformer is connected to the power grid, the pre-magnetized transformer (i.e., the small transformer) will stop working and exit the system. However, in the traditional pre-magnetization circuit, there are some components that are easy to damage or fall off, such as time relays that need to be unplugged during use. When these components are damaged or fall off, it is easy to interrupt the pre-magnetization process or cause other more serious damage, thereby affecting the effect of pre-magnetization. Summary of the invention

[0004] In order to solve the technical problem that the pre-magnetization is affected when the above-mentioned fragile element is damaged, the present invention provides solutions in the following aspects.

[0005] In the first aspect, the present invention provides a pre-magnetization control device, comprising: a microcontroller and a signal acquisition circuit, a relay output circuit, and a crystal oscillator circuit respectively connected to the microcontroller, wherein the signal acquisition circuit is used to collect trigger signals and control signals generated by system operation, the relay output circuit is used to control the start and stop of pre-magnetization, and the crystal oscillator circuit is used to control the time of pre-magnetization.

[0006] Furthermore, the trigger signal includes a closing signal and an opening signal, and the signal acquisition circuit includes a first acquisition circuit and a second acquisition circuit, the first acquisition circuit is connected to the microcontroller for collecting the closing signal and the control signal, and the second acquisition circuit is connected to the microcontroller for collecting the opening signal and the control signal.

[0007] Further, it is characterized in that the first acquisition circuit includes a first optocoupler, a sixth resistor, a seventh resistor, an eleventh capacitor, and a first voltage regulator diode; the eleventh capacitor is connected between the third pin and the fourth pin of the first optocoupler, the fourth pin of the first optocoupler is respectively connected to the seventh resistor and the microcontroller, and the sixth resistor and the first voltage regulator diode are connected between the first pin and the second pin of the first optocoupler.

[0008] The second acquisition circuit includes a second optocoupler, a ninth resistor, a tenth resistor, a twelfth capacitor, and a second voltage regulator diode; the twelfth capacitor is connected between the third pin and the fourth pin of the second optocoupler, the fourth pin of the second optocoupler is respectively connected to the tenth resistor and the microcontroller, and the ninth resistor and the second voltage regulator diode are connected between the first pin and the second pin of the second optocoupler.

[0009] Further, the crystal oscillator circuit includes a crystal, a first resistor, an eighth capacitor, and a ninth capacitor. The first resistor is connected between the first pin and the third pin of the crystal, the eighth capacitor is connected to the third pin of the crystal, and the ninth capacitor is connected between the first pin and the fourth pin of the crystal.

[0010] Further, the relay output circuit includes a first triode, a second triode, a first relay, a second relay, a third relay, and a fourth relay. The third pin of the first relay is connected to the third pin of the fourth relay, and the first pin of the first relay is connected to the first pin of the second relay and then sequentially connected to the first triode and the microcontroller.

[0011] And the third pin of the second relay is connected to the third pin of the third relay. After the first pin of the third relay is connected to the first pin of the fourth relay, it is sequentially connected to the second triode and the microcontroller, and a diode is connected between the first pin of each relay and the common ground terminal.

[0012] Further, it further includes a power supply circuit. The power supply circuit includes a voltage regulator, a sixth capacitor, a seventh capacitor, and a fuse. The third pin of the voltage regulator is connected to the common ground terminal through the seventh capacitor. After the second pin and the fourth pin of the voltage regulator are connected, they are connected to the sixth capacitor and then connected to the common ground terminal. The fourth pin of the voltage regulator is sequentially connected to the fuse and the power supply voltage.

[0013] Further, it further includes a 485 circuit. The 485 circuit includes a 485 chip, a common mode inductor, a first semiconductor discharge tube, a second semiconductor discharge tube, and a third semiconductor discharge tube. The 485 chip is connected to the microcontroller. The first pin and the second pin of the common mode inductor are respectively connected to the seventh pin and the sixth pin of the 485 chip. The fourth pin of the common mode inductor is connected to the common ground terminal through the first semiconductor discharge tube. The third pin of the common mode inductor is connected to the common ground terminal through the third semiconductor discharge tube. The second semiconductor discharge tube is connected between the third pin and the fourth pin of the common mode inductor.

[0014] Further, the microcontroller is one of the STM32 series.

[0015] In a second aspect, the present invention provides a pre-magnetization control circuit, including a closing button and a tripping button. It further includes the pre-magnetization control device according to any one of the first aspect, and a first switching device, a second switching device, and a third switching device respectively connected to the pre-magnetization control device.

[0016] Further, the first switching device, the second switching device, and the third switching device are contactors or circuit breakers.

[0017] The beneficial effects of the present invention are as follows: During the pre-magnetization control process, the pre-magnetization control device of the present invention can effectively control the closing excitation inrush current of the pre-magnetization process of the transformer, ensure that the inrush current when the transformer is closed is less than the protection current of the circuit breaker at the front end of the transformer, and make the transformer more smoothly excited and closed. At the same time, it can reduce the impact of the closing inrush current on the circuit breaker, extend the service life of the circuit breaker, and avoid the problem that components such as time relays that are prone to damage may affect the pre-magnetization effect of the transformer, thereby improving work efficiency, and the wiring is also more concise compared to traditional pre-magnetization cables. In addition, since a controller with a logic program can be used, various different pre-magnetization requirements can be met, and the universality is strong. Description of the Drawings

[0018] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features, and advantages of the exemplary embodiments of the present invention will become easily understandable. In the drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, where:

[0019] Figure 1 is a traditional pre-magnetization control circuit;

[0020] Figure 2 is a schematic block diagram showing the structure of the pre-magnetization control device according to an embodiment of the present invention;

[0021] Figure 3 is a microcontroller that schematically shows a pre - magnetization control device according to an embodiment of the present invention;

[0022] Figure 4 is a topology diagram that schematically shows a signal acquisition circuit of a pre - magnetization control device according to an embodiment of the present invention;

[0023] Figure 5 is a topology diagram that schematically shows a crystal oscillator circuit of a pre - magnetization control device according to an embodiment of the present invention;

[0024] Figure 6 is a topology diagram that schematically shows a relay output circuit of a pre - magnetization control device according to an embodiment of the present invention;

[0025] Figure 7 is a topology diagram that schematically shows a power supply circuit of a pre - magnetization control device according to an embodiment of the present invention;

[0026] Figure 8 is a topology diagram that schematically shows a 485 circuit of a pre - magnetization control device according to an embodiment of the present invention;

[0027] Figure 9 is a pre - magnetization control circuit that schematically shows according to an embodiment of the present invention. Detailed Embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0029] Next, the detailed embodiments of the present invention will be described in detail in conjunction with the accompanying drawings.

[0030] As Figure 1 can be seen, there are a time relay and an indicator light in the traditional pre - magnetization control circuit. Among them, the time relay is used to control the time of pre - magnetization, and the indicator light is used to visually display the signals of the start and end states of pre - magnetization. However, the time relay is prone to damage or detachment. When damage or detachment occurs, the pre - magnetization process of the transformer will be interrupted, thus affecting the efficiency of pre - magnetization. Moreover, the traditional pre - magnetization control circuit cannot flexibly meet various requirements (the delay range of some time relays is fixed and cannot meet the diverse requirements for time accuracy in the pre - magnetization process, and the functions are single).

[0031] To solve the above - mentioned technical problems, in the first aspect, the present invention proposes a pre - magnetization control device, as Figure 2As shown in the figure, the pre-magnetization control device of the present invention includes a microcontroller, and a signal acquisition circuit, a relay output circuit, a crystal oscillator circuit, a power supply circuit, and a 485 circuit that are respectively connected to the microcontroller. Among them, the signal acquisition circuit is used to acquire trigger signals (including closing signals triggered by the closing button and opening signals triggered by the opening button) and control signals generated during system operation; the relay output circuit is used to control the start and stop of pre-magnetization; the crystal oscillator circuit is used to control the time of pre-magnetization; the power supply circuit is used to supply power to the microcontroller and others; the 485 circuit is used for remote communication to achieve instruction issuance.

[0032] Specifically, in combination with Figures 3 to 8 the pre-magnetization control device of the present invention will be described. Among them, Figure 3 is a schematic diagram of the pins of the microcontroller and the external connection relationship. In one embodiment, the microcontroller (U2) is one of the STM32 series, and those skilled in the art can select a suitable model or a suitable microcontroller (single-chip microcomputer) according to actual needs. By inputting a preset logic program into the microcontroller (the input-output logic relationship and related parameters can be edited through the communication interface), various different pre-magnetization requirements can be met, such as timed magnetization requirements, magnetization duration, etc.

[0033] In one embodiment, the signal acquisition circuit in the pre-magnetization control device of the present invention is as Figure 4 shown. In this embodiment, the signal acquisition circuit includes a first acquisition circuit and a second acquisition circuit, and both the first acquisition circuit and the second acquisition circuit are connected to the microcontroller.

[0034] Specifically, the first acquisition circuit is used to acquire the closing signal and the control signal, and includes a first optocoupler (U3), a sixth resistor (R6), a seventh resistor (R7), an eleventh capacitor (C11), a first zener diode (D4), and a second fuse (F2); the eleventh capacitor is connected between the third pin and the fourth pin of the first optocoupler, the fourth pin of the first optocoupler is respectively connected to the seventh resistor and the microcontroller, the sixth resistor and the first zener diode are connected between the first pin and the second pin of the first optocoupler, and the second fuse is connected to the positive electrode of the first zener diode.

[0035] The second acquisition circuit is used to acquire the opening signal and the control signal, and includes a second optocoupler (U4), a ninth resistor (R9), a tenth resistor (R10), a twelfth capacitor (C12), a second zener diode (D5), and a third fuse (F3); the twelfth capacitor is connected between the third pin and the fourth pin of the second optocoupler, the fourth pin of the second optocoupler is respectively connected to the tenth resistor and the microcontroller, the ninth resistor and the second zener diode are connected between the first pin and the second pin of the second optocoupler, and the third fuse is connected to the positive electrode of the second zener diode.

[0036] By acquiring the trigger signal and the control signal, the pre-magnetization timing can be accurately controlled, the magnetization parameters (such as the pre-magnetization time) can be adjusted, and the pre-magnetization safety can be ensured (when an abnormal situation occurs during the pre-magnetization process, an alarm can be issued in time and / or the magnetization operation can be stopped).

[0037] In one embodiment, the crystal oscillator circuit in the pre-magnetization control device of the present invention is as Figure 5 shown. The crystal oscillator circuit includes a crystal (TX), a first resistor (R1), an eighth capacitor (C8), and a ninth capacitor (C9). The first resistor is connected between the first pin and the third pin of the crystal, the eighth capacitor is connected to the third pin of the crystal, and the ninth capacitor is connected between the first pin and the fourth pin of the crystal.

[0038] In addition, the crystal oscillator circuit further includes a first capacitor (C1), a second capacitor (C2), a third capacitor (C3), a fourth capacitor (C4), and a fifth capacitor (C5) connected in parallel, which are used to filter the voltage output by the power supply to ensure that the pre-magnetization control device can work normally in a stable power supply environment.

[0039] The crystal oscillator circuit further includes a second resistor (R2) and a tenth capacitor (C10) connected in series. The connection point between the second resistor and the tenth capacitor is connected to the 7th pin (NRST, reset pin) of the microcontroller to implement the power-on reset function of the microcontroller.

[0040] In one embodiment, the relay output circuit in the pre-magnetization control device of the present invention is as Figure 6As shown. The relay output circuit includes a first triode (Q1), a second triode (Q2), a fourth resistor (R4), an eighth resistor (R8), a first relay (K1), a second relay (K2), a third relay (K3), and a fourth relay (K4). The third pin of the first relay is connected to the third pin of the fourth relay. The first pin of the first relay is connected to the first pin of the second relay and then connected to the first triode and the microcontroller in sequence. The fourth resistor is connected between the base and the emitter of the first triode. And the third pin of the second relay is connected to the third pin of the third relay. The first pin of the third relay is connected to the first pin of the fourth relay and then connected to the second triode and the microcontroller in sequence. The eighth resistor is connected between the base and the emitter of the second triode. And corresponding diodes (D1, D2, D3, D4) are connected between the first pin of each relay and the common ground terminal.

[0041] In addition, the relay output circuit further includes a fifth resistor (R5), an eleventh resistor (R11), a first LED (LED1), and a second LED (LED2). Among them, the serially connected fifth resistor and the first LED are connected to the collector of the first triode to indicate the start state of pre-magnetization. The serially connected eleventh resistor and the second LED are connected to the collector of the second triode to indicate the state of being magnetized.

[0042] In one embodiment, the power supply circuit in the pre-magnetization control device of the present invention is as Figure 7 shown, in which a connector (P1) and its connection relationship are also shown. The power supply circuit includes a voltage regulator (U1), a sixth capacitor (C6), a seventh capacitor (C7), and a first fuse (F1). The third pin of the voltage regulator is connected to the seventh capacitor and then connected to the common ground terminal. The second pin of the voltage regulator is connected to the fourth pin and then connected to the sixth capacitor and connected to the common ground terminal. The fourth pin of the voltage regulator is sequentially connected to the first fuse and the power supply voltage (VCC3.3).

[0043] In one embodiment, the 485 circuit in the pre-magnetization control device of the present invention is as Figure 8As shown in the figure, the 485 circuit includes a 485 chip (U5), a common mode inductor (L1), a twelfth resistor (R12), a fourteenth resistor (R14), a thirteenth capacitor (C13), a first semiconductor discharge tube (TSS1), a second semiconductor discharge tube (TSS2), and a third semiconductor discharge tube (TSS3). The 485 chip is connected to the microcontroller. The first pin and the second pin of the common mode inductor are respectively connected to the seventh pin and the sixth pin of the 485 chip. The fourth pin of the common mode inductor is connected to the first semiconductor discharge tube. The third pin of the common mode inductor is connected to the third semiconductor discharge tube. The second semiconductor discharge tube is connected between the third pin and the fourth pin of the common mode inductor. The twelfth resistor and the fourteenth resistor are respectively connected to the first pin (R, receive output pin) of the 485 chip.

[0044] The 485 circuit further includes a thirteenth resistor (R13), a fifteenth resistor (R15), a sixteenth resistor (R16), and a third triode (Q3). The UART_TX pin is connected to the base of the third triode through the fifteenth resistor. The base of the third triode is also connected to the common ground terminal through the sixteenth resistor. The collector of the third triode is connected with the thirteenth resistor.

[0045] The pre-charge magnetic control device of the present invention is applicable to the closing start of a transformer with a pre-charge magnetic transformer and a control system, can effectively control the closing excitation inrush current of the transformer, ensure that the surge current during transformer closing is less than the protection current of the circuit breaker at the front end of the transformer, and enable the transformer to be more smoothly excited and closed; at the same time, it can reduce the impact of the closing surge current on the circuit breaker, extend the service life of the circuit breaker, and make the power consumption safer.

[0046] By integrating some functions of the pre-charge magnetic control circuit into one body to form a pre-charge magnetic control device, components such as time relays and indicator lights that are prone to damage can be eliminated, greatly improving the work efficiency. At the same time, the wiring of the pre-charge magnetic control circuit is also made more concise. In addition, the pre-charge magnetic control device can perform network control and digital control, with more intelligent, precise control and higher integration.

[0047] In the second aspect, the present invention also provides a pre-charge magnetic control circuit, which includes the pre-charge magnetic control device of the above embodiment, as well as a closing button, a tripping button, a first switching device, a second switching device, and a third switching device respectively connected to the pre-charge magnetic control device. In one embodiment, the first switching device, the second switching device, and the third switching device can be contactors or circuit breakers.

[0048] Specifically, the pre-charge magnetic control circuit of the present invention is as Figure 9As shown, a pre-magnetizing circuit and a main circuit are also shown. Through the pre-magnetizing control circuit of the present invention, the pre-magnetizing process of the transformer can be automatically realized.

[0049] The present invention optimizes and improves the traditional pre-magnetizing control circuit (such as Figure 1 shown). By using an integrated pre-magnetizing control device, the time relays and indicator lights that are prone to damage and detachment in the traditional pre-magnetizing circuit are removed, making the entire pre-magnetizing control circuit (such as Figure 8 shown) more convenient and intelligent, and also more convenient for wiring, operation, and maintenance. Moreover, 24V DC low-voltage electricity is used for control, making the control safer.

[0050] Further, when using the pre-magnetizing control device of the present invention for pre-magnetizing, press the closing button SB1. The pre-magnetizing control device gives a delay signal for powering on the pre-magnetizing transformer (T2). Thereafter, the coil of KM1 (corresponding to the second switching device) is energized, KM1 closes, and the pre-magnetizing transformer is powered on. After KM1 closes, its normally open contact closes, giving an instruction to the pre-magnetizing control device. The pre-magnetizing control device gives a pre-magnetizing delay signal. Then, the coil of KM2 (corresponding to the third switching device) is energized, KM2 closes, and the pre-magnetizing transformer starts pre-magnetizing. After KM2 closes, its normally open contact closes, giving an instruction to the pre-magnetizing control device. The pre-magnetizing control device gives a closing delay signal for the main contactor (i.e., KM in the figure). Thereafter, the coil of KM (corresponding to the first switching device) is energized, KM closes, and the pre-magnetizing of the transformer (i.e., T1 in the figure) is completed. After the pre-magnetizing of the transformer is completed, after KM closes, its normally open contact closes to complete self-locking and operate normally. At the same time, the pre-magnetizing control device gives a signal to disconnect KM1 and KM2. Press the stop and opening button SB2, the main contactor opens, and the main transformer is de-energized. Thus, the pre-magnetizing operation of the transformer is completed.

[0051] In all the examples shown and described here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. In addition, different models of components can also be selected as long as the same function can be achieved.

[0052] Although this specification has shown and described multiple embodiments of the present invention, it is obvious to those skilled in the art that such embodiments are provided only by way of example. Those skilled in the art will think of many changes, alterations, and alternative ways without departing from the spirit and idea of the present invention. It should be understood that various alternative solutions to the embodiments of the present invention described herein can be adopted in the practice of the present invention.

Claims

1. A pre-magnetization control device, characterized in that, Comprising: A microcontroller, and a signal acquisition circuit, a relay output circuit, and a crystal oscillator circuit respectively connected to the microcontroller. Among them, the signal acquisition circuit is used to acquire trigger signals and control signals generated during system operation, the relay output circuit is used to control the start and stop of pre-magnetization, and the crystal oscillator circuit is used to control the time of pre-magnetization.

2. The pre-magnetization control device according to claim 1, wherein The trigger signals include closing signals and opening signals. The signal acquisition circuit includes a first acquisition circuit and a second acquisition circuit. The first acquisition circuit is connected to the microcontroller and is used to acquire the closing signals and the control signals. The second acquisition circuit is connected to the microcontroller and is used to acquire the opening signals and the control signals.

3. The pre-magnetization control device according to claim 2, characterized in that The first acquisition circuit includes a first optocoupler, a sixth resistor, a seventh resistor, an eleventh capacitor, and a first voltage regulator diode. The eleventh capacitor is connected between the third pin and the fourth pin of the first optocoupler. The fourth pin of the first optocoupler is respectively connected to the seventh resistor and the microcontroller. The sixth resistor and the first voltage regulator diode are connected between the first pin and the second pin of the first optocoupler. The second acquisition circuit includes a second optocoupler, a ninth resistor, a tenth resistor, a twelfth capacitor, and a second voltage regulator diode. The twelfth capacitor is connected between the third pin and the fourth pin of the second optocoupler. The fourth pin of the second optocoupler is respectively connected to the tenth resistor and the microcontroller. The ninth resistor and the second voltage regulator diode are connected between the first pin and the second pin of the second optocoupler.

4. The pre-magnetization control device according to claim 1, characterized in that, The crystal oscillator circuit includes a crystal, a first resistor, an eighth capacitor, and a ninth capacitor. The first resistor is connected between the first pin and the third pin of the crystal. The eighth capacitor is connected to the third pin of the crystal. The ninth capacitor is connected between the first pin and the fourth pin of the crystal.

5. The pre-magnetization control device according to claim 1, characterized in that The relay output circuit includes a first triode, a second triode, a first relay, a second relay, a third relay, and a fourth relay. The third pin of the first relay is connected to the third pin of the fourth relay. After the first pin of the first relay is connected to the first pin of the second relay, they are sequentially connected to the first triode and the microcontroller. And the third pin of the second relay is connected to the third pin of the third relay. After the first pin of the third relay is connected to the first pin of the fourth relay, they are sequentially connected to the second triode and the microcontroller. And a diode is connected between the first pin of each relay and the common ground terminal.

6. The pre-magnetization control device according to claim 1, characterized in that, It further includes a power supply circuit. The power supply circuit includes a voltage regulator, a sixth capacitor, a seventh capacitor, and a fuse. The third pin of the voltage regulator is connected to the common ground terminal through the seventh capacitor. After the second pin and the fourth pin of the voltage regulator are connected, they are connected to the sixth capacitor and then connected to the common ground terminal. The fourth pin of the voltage regulator is sequentially connected to the fuse and the power supply voltage.

7. The pre-magnetization control device according to claim 1, characterized in that, It further includes a 485 circuit, and the 485 circuit includes a 485 chip, a common mode inductor, a first semiconductor discharge tube, a second semiconductor discharge tube, and a third semiconductor discharge tube. The 485 chip is connected to the microcontroller. The first pin and the second pin of the common mode inductor are respectively connected to the seventh pin and the sixth pin of the 485 chip. The fourth pin of the common mode inductor is connected to the common ground terminal through the first semiconductor discharge tube. The third pin of the common mode inductor is connected to the common ground terminal through the third semiconductor discharge tube. The second semiconductor discharge tube is connected between the third pin and the fourth pin of the common mode inductor.

8. The pre-magnetization control circuit according to claim 1, wherein The microcontroller is one of the STM32 series.

9. A pre-magnetization control circuit, including a closing button and a tripping button, is characterized in that It further includes the pre-magnetization control device according to any one of claims 1-8, and a first switching device, a second switching device, and a third switching device respectively connected to the pre-magnetization control device.

10. The pre-magnetization control circuit according to claim 9, characterized in that, The first switching device, the second switching device, and the third switching device are contactors or circuit breakers.

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