Transformer opening overvoltage eliminator

Abstract

An overvoltage eliminator comprises a control module, a rectification module, an inversion module and an alternating current filter, the alternating current side of the rectification module is used for being connected with an excitation power source, the direct current side of the rectification module is connected with the direct current side of the inversion module, and the alternating current side of the inversion module is connected with the input end of the alternating current filter. The output end of the AC filter is used for outputting AC voltage to the load side of the main transformer; the control end of the rectification module and the control end of the inversion module are connected with the control signal output end of the control module, the voltage signal input end of the control module is connected with the output end of the alternating current filter, and the modulation wave signal input end of the control module is used for receiving a main transformer power side voltage signal. According to the design, the overvoltage generated when the no-load transformer is switched off can be eliminated, so that the transformer and the switch equipment are not impacted by the overvoltage, and the damage of the overvoltage to the transformer and the switch equipment is avoided.

Description

Technical Field

[0001] The utility model relates to the field of power equipment, in particular to a transformer switching overvoltage eliminator, which is specifically applicable to eliminating the overvoltage generated by the no-load disconnection of a transformer. Background Art

[0002] A transformer is an important device for energy conversion in a power system. During conventional operations such as using a switch to disconnect a no-load transformer, overvoltages with relatively high amplitudes may be generated. Especially for electric furnace transformers and electric locomotive transformers in steel mills, these transformers are characterized by frequent no-load operations. To reduce the operation and maintenance burden on switchgear, vacuum circuit breakers are usually used. Vacuum circuit breakers have a particularly strong current interruption ability, but this will also cause switching overvoltages with a relatively high probability and extremely high amplitudes. The frequent action of high-amplitude chopped-wave overvoltages on the transformer windings is the main cause of transformer breakdown and flashover accidents. In addition, this overvoltage on the high-voltage side of the transformer is reversely superimposed on the power supply voltage, which will generate a quite high recovery voltage across the vacuum circuit breaker, leading to the phenomenon of arc reignition between the breaker contacts, posing a great threat to the safe operation of the power grid and equipment, and may cause huge economic losses. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a transformer switching overvoltage eliminator in view of the deficiencies of the above-mentioned prior art, which can completely eliminate the overvoltage generated during the switching off of a no-load transformer, protect the transformer and switchgear from the impact of overvoltage, and avoid the harm of overvoltage to the power grid system and switchgear.

[0004] To achieve the above object, the technical solution of the present utility model is as follows:

[0005] A transformer switching overvoltage eliminator, the overvoltage eliminator includes a control module, a rectification module, an inversion module, and an AC filter. The AC side of the rectification module is used to connect to an excitation power supply, the DC side of the rectification module is connected to the DC side of the inversion module, the AC side of the inversion module is connected to the input end of the AC filter, and the output end of the AC filter is used to output an AC voltage to the load side of the main transformer;

[0006] The control end of the rectification module and the control end of the inversion module are both connected to the control signal output end of the control module. The voltage signal input end of the control module is connected to the output end of the AC filter, and the modulation wave signal input end of the control module is used to receive the voltage signal of the power supply side of the main transformer.

[0007] A bypass DC relay, a charging resistor, and a DC capacitor are provided between the rectification module and the inversion module. One end of the DC capacitor is connected to the negative pole of the DC side of the inversion module and the negative pole of the DC side of the rectification module, and the other end of the DC capacitor is connected to the positive pole of the DC side of the inversion module, one end of the charging resistor, and one end of the bypass DC relay. The other end of the charging resistor and the other end of the bypass DC relay are connected to the positive pole of the DC side of the rectification module, and the control coil of the bypass DC relay is connected to the control signal output end of the control module.

[0008] A DC fuse is provided at the positive pole of the DC side of the rectification module;

[0009] An AC fuse is provided at the output end of the AC filter.

[0010] Both the rectification module and the inversion module include multiple groups of high-power power electronic devices and a PWM drive circuit;

[0011] The control signal output end of the control module is connected to the PWM drive circuit of the rectification module and the PWM drive circuit of the inversion module.

[0012] The modulation wave signal input end of the control module is connected to the power grid system through a voltage transformer.

[0013] The overvoltage eliminator further includes an output switch and an output terminal circuit breaker. The output end of the AC filter is connected to one end of the output switch, the other end of the output switch is connected to one end of the output terminal circuit breaker, and the other end of the output terminal circuit breaker is used to connect to the load side of the main transformer;

[0014] The control coil of the output switch and the control coil of the output terminal circuit breaker are both connected to the control signal output end of the control module.

[0015] The load side of the main transformer is simultaneously connected to one end of the output switch far from the output terminal circuit breaker and one end of the load side circuit breaker. The other end of the load side circuit breaker is connected to the load system, the power supply side of the main transformer is connected to one end of the system side circuit breaker, and the other end of the system side circuit breaker is connected to the power grid system;

[0016] The control coil of the system side circuit breaker is connected to the control signal output end of the control module.

[0017] The output terminal circuit breaker is a low-voltage plastic case circuit breaker.

[0018] In some other embodiments, the overvoltage eliminator further includes an excitation transformer provided between the output switch and the output terminal circuit breaker. The low-voltage side of the excitation transformer is connected to one end of the output switch far from the AC filter, and the high-voltage side of the excitation transformer is connected to one end of the output terminal circuit breaker far from the main transformer.

[0019] The load side of the main transformer is simultaneously connected to one end of the output terminal breaker and one end of the far-excitation transformer, and the other end of the load side breaker is connected to the load system. The power supply side of the main transformer is connected to one end of the system side breaker, and the other end of the system side breaker is connected to the power grid system;

[0020] The control coil of the system side breaker is connected to the control signal output end of the control module.

[0021] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0022] 1. A transformer closing overvoltage eliminator of the present utility model includes a rectification module, an inversion module, and an AC filter connected in sequence. The rectification module is connected to an AC excitation power supply. The alternating current provided by the AC excitation power supply passes through the rectification module, the inversion module, and the AC filter in sequence and then outputs a standard AC power supply. The output of the overvoltage eliminator can be adjusted by controlling the rectification module and the inversion module. When the main transformer without load is removed from the system, the output end of the AC filter is connected to the load side of the main transformer, and the inversion module is controlled to operate so that the voltage output by the overvoltage eliminator is the same as the amplitude and phase of the no-load voltage on the load side of the main transformer. At this time, the two power supplies are connected in parallel through the transformer coil; then the system side breaker on the power supply side of the main transformer is disconnected. At this time, the overvoltage eliminator operates with the main transformer under load, and the excitation current of the main transformer is provided by the overvoltage eliminator; subsequently, the inversion module is controlled to gradually reduce the amplitude of the voltage output by the overvoltage eliminator to 0, completing the shutdown process of the main transformer, and the main transformer is removed from the system. Since the load side current of the transformer is continuously provided by the transformer overvoltage eliminator when the system side breaker is opened, no cut-off overvoltage will be generated when the system side breaker is opened, effectively protecting equipment such as transformers and switches in the system. Therefore, this design can eliminate the cut-off overvoltage during the removal of the no-load transformer and effectively protect equipment such as transformers and switches in the system.

[0023] 2. The control module of a kind of transformer switching overvoltage eliminator of the utility model has two voltage signal input ends. Among them, the modulation wave signal input end of the control module receives the voltage signal on the power supply side of the main transformer. The controller module outputs a PWM control signal according to the voltage signal on the power supply side of the main transformer to drive the rectification module and the inversion module to operate, provides a modulation wave for the inversion module, and the control module then controls the operation of the inversion module according to the amplitude and phase control data input by the operator. The overvoltage eliminator can output a voltage with the same amplitude and phase as the no-load voltage on the load side of the main transformer. At the same time, the voltage signal input end of the control module is connected to the output end of the AC filter 4. The control module can judge whether the main transformer is in the operating state according to the signal received by the voltage signal input end, avoiding misoperation. Therefore, in this design, the control module controls the inversion module to operate with the voltage signal on the power supply side of the main transformer as the modulation wave, and the overvoltage eliminator can output a voltage with the same amplitude and phase as the no-load voltage on the load side of the main transformer, with a high degree of automation. At the same time, the control module judges whether the main transformer is in the operating state according to the signal received by the voltage signal input end, avoiding misoperation.

[0024] 3. The rectification module and the inversion module in a kind of transformer switching overvoltage eliminator of the utility model are composed of high-power power electronic devices and a PWM drive circuit. At the same time, the control signal output ends of the control module are respectively connected to the control ends of the rectification module and the inversion module. When the no-load transformer is removed from the system, by outputting a control signal through the control module, the operation of the rectification module and the inversion module can be accurately controlled, and voltages with corresponding phases and amplitudes are output, and the control method is mature and simple. Therefore, the rectification module and the inversion module in this design are composed of high-power power electronic devices and a PWM drive circuit, and are controlled by the control module, with high operating power, high control accuracy and good stability of the equipment.

[0025] 4. A kind of transformer switching overvoltage eliminator of the utility model further includes an excitation transformer, which is connected to the output end of the AC filter. For a system where the voltage on the low-voltage side of the main transformer is greater than 660V, the alternating current output by the AC filter is stepped up through the excitation transformer to adapt to the no-load removal operation of the main transformer in a system where the voltage on the low-voltage side is greater than 660V. Therefore, in this design, by setting an excitation transformer at the output end of the AC filter, the voltage eliminator can be applicable to a system where the voltage on the low-voltage side of the main transformer is greater than 660V. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a structural schematic diagram of a kind of transformer switching overvoltage eliminator of the utility model.

[0027] Figure 2 is another structural schematic diagram of a kind of transformer switching overvoltage eliminator of the utility model.

[0028] In the figure: control module 1, rectification module 2, inversion module 3, AC filter 4, output switch K1, output terminal circuit breaker K2, load side circuit breaker K3, system side circuit breaker K4, main transformer T1, excitation transformer T2, bypass DC relay K, charging resistor R, DC capacitor C, AC fuse FU1, DC fuse FU2, voltage transformer PT. Specific implementation mode

[0029] The present utility model will be further described in detail below in conjunction with the accompanying drawing description and specific implementation mode.

[0030] See Figure 1 , a transformer closing overvoltage eliminator, the overvoltage eliminator includes a control module 1, a rectification module 2, an inversion module 3, and an AC filter 4. The AC side of the rectification module 2 is used to connect to an excitation power supply, the DC side of the rectification module 2 is connected to the DC side of the inversion module 3, the AC side of the inversion module 3 is connected to the input end of the AC filter 4, and the output end of the AC filter 4 is used to output an AC voltage to the load side of the main transformer T1.

[0031] The control end of the rectification module 2 and the control end of the inversion module 3 are both connected to the control signal output end of the control module 1. The voltage signal input end of the control module 1 is connected to the output end of the AC filter 4, and the modulation wave signal input end of the control module 1 is used to receive the grid system voltage signal on the power supply side of the main transformer T1.

[0032] The voltage signal input end of the control module 1 is connected to the other end of the system side circuit breaker K4 through a voltage transformer PT.

[0033] In this embodiment, both the rectification module 2 and the inversion module 3 include multiple groups of high-power power electronic devices and a PWM drive circuit;

[0034] The control signal output end of the control module 1 is connected to the PWM drive circuit of the rectification module 2 and the PWM drive circuit of the inversion module 3.

[0035] The control module 1 is used to control the operation of the inversion module 3 according to the grid system voltage signal received by the modulation wave signal input end as the modulation wave and the phase difference between the voltage on the power supply side and the voltage on the load side of the main transformer, so that the overvoltage eliminator can output a voltage with the same phase as the no-load operating voltage on the load side.

[0036] Specifically, the core CPU of the control module 1 is connected to the PWM drive circuits of the rectification module 2 and the inversion module 3 through a bus and a parallel interface circuit. The control module 1 sends control commands to the gates of the high-power power electronic devices in the rectification module 2 and the inversion module 3 through the PWM drive circuits, controls the conduction and cut-off of the high-power power electronic devices, and thus can control the operation of the rectification module 2 and the inversion module 3 and adjust the outputs of the rectification module 2 and the inversion module 3.

[0037] Among them, the rectification module 2 is a three-phase uncontrolled rectification module or a three-phase controlled rectification module, and the inversion module 3 is a three-phase fully controlled inversion module. The inversion module 3 adopts a two-level control method or a three-level control method in the three-phase full control inversion process. Among them, the two-level control method means that the inversion module 3 can only generate two level states, namely high level and low level, when outputting, and the three-level control method means that the inversion module 3 generates three level states, namely high level, zero level and low level, when outputting.

[0038] Since the voltage signal input terminal of the control module 1 is connected to the output terminal of the AC filter 4, the modulation wave signal input terminal of the control module 1 is used to receive the voltage signal on the power supply side of the main transformer T1. When controlling the output, the voltage output by the AC filter 4 and the voltage on the power supply side of the main transformer T1 are sequentially connected to the core CPU of the control module 1 through a voltage converter, a voltage formation and operational amplifier circuit, and an AD converter. The core CPU uses the voltage on the power supply side of the main transformer T1 (i.e., the grid system voltage) as the modulation wave and controls the operation of the rectification module 2 and the inversion module 3 through the parallel interface circuit, so that the overvoltage eliminator outputs a voltage whose phase and amplitude meet the operation requirements.

[0039] In this embodiment, an excitation power supply is connected to the AC side of the rectification module 2. The DC side of the rectification module 2 is connected to the DC side of the inverter, and a bypass DC relay K, a charging resistor R, and a DC capacitor C are arranged between the rectification module 2 and the inversion module 3. One end of the DC capacitor C is connected to the negative pole of the DC side of the inversion module 3 and the negative pole of the DC side of the rectification module 2, and the other end of the DC capacitor C is connected to the positive pole of the DC side of the inversion module 3, one end of the charging resistor R, and one end of the bypass DC relay K. The other end of the charging resistor R and the other end of the bypass DC relay K are connected to the positive pole of the DC side of the rectification module 2. The control coil of the bypass DC relay K is connected to the control signal output terminal of the control module 1.

[0040] Specifically, according to needs, the excitation power supply can adopt a 400V / 660V three-phase AC power supply, which is converted into direct current through the rectification module 2, filtered by the DC capacitor C, converted into alternating current through the PWM inversion module 3, and then filtered by the AC filter electrical appliance 4 to output a standard controllable AC excitation voltage.

[0041] The overvoltage eliminator further includes an output switch K1 and an output terminal circuit breaker K2. The output terminal of the AC filter 4 is connected to one end of the output switch K1. The other end of the output switch K1 is connected to one end of the output terminal circuit breaker K2. The other end of the output terminal circuit breaker K2 is used to connect to the load side of the main transformer T1.

[0042] The control coils of the output switch K1 and the output terminal circuit breaker K2 are both connected to the control signal output terminal of the control module 1.

[0043] The control module 1 can control the opening and closing of the output switch K1 and each circuit breaker through control signals, as well as the feedback of the status. Specifically, the core CPU of the control module 1 is respectively connected to the opening and closing coils of the output switch K1, the output terminal circuit breaker K2, the system side circuit breaker K4, and the bypass DC relay K through a parallel interface circuit and an optoelectronic isolator, so as to control the opening and closing of the above switches and circuit breakers. At the same time, the switch states of the output switch K1, the output terminal circuit breaker K2, the load side circuit breaker K3, the system side circuit breaker K4, and the bypass DC relay K are connected to the core CPU through an optoelectronic isolator and a parallel interface circuit, enabling the core CPU to judge the opening and closing states of the above switches and circuit breakers.

[0044] A DC fuse FU2 is provided at the positive pole of the DC side of the rectification module 2; an AC fuse FU1 is provided at the output terminal of the AC filter 4. The AC fuse FU1 and the DC fuse FU2 are used for short - circuit and over - current protection.

[0045] In some embodiments, when the no - load operating voltage of the load side of the main transformer T1 is relatively low, for example, when the no - load operating voltage of the load side of the main transformer T1 is lower than 660V, the voltage is directly output to the load side of the main transformer T1 through the AC filter 4. As Figure 1 shown, the output switch K1 is directly connected to the output terminal circuit breaker K2 through a connection line. The load side of the main transformer T1 is simultaneously connected to one end of the output terminal circuit breaker K2 far from the output switch K1 and one end of the load side circuit breaker K3. The other end of the load side circuit breaker K3 is connected to the load system. The power supply side of the main transformer T1 is connected to one end of the system side circuit breaker K4. The other end of the system side circuit breaker K4 is connected to the power grid system and the modulation wave signal input terminal of the control module 1. The control coil of the system side circuit breaker K4 is connected to the control signal output terminal of the control module 1.

[0046] In some embodiments, when the no - load operating voltage of the load side of the main transformer T1 is relatively low, the output terminal circuit breaker K2 can use a low - voltage molded case circuit breaker.

[0047] When the no-load operating voltage on the load side of the main transformer T1 is relatively low, when the main transformer T1 is removed from the system, the main transformer T1 is in a no-load operating state. Since the output end of the AC filter 4 is connected to the load side of the main transformer T1 sequentially through the AC fuse FU1, the output switch K1, and the output terminal circuit breaker K2, under the control of the control module 1, the control module 1 uses the system voltage on the power supply side of the main transformer T1 as the modulation wave, and according to the calculated phase control data, as well as the amplitude and phase data input by the operator, controls the operation of the inverter module 3, so that the voltage output by the inverter module after passing through the AC filter 4 is the same as the exciting voltage of the main transformer. At this time, the two power supplies are connected in parallel through the transformer coil. When the system-side circuit breaker trips, the no-load transformer overvoltage eliminator with load transformer operation is completed, and the exciting current of the transformer is provided by the no-load transformer overvoltage eliminator. Then, under the control of the main control system, the output voltage amplitude of the no-load transformer overvoltage eliminator is gradually reduced until it is reduced to 0, and the no-load transformer overvoltage eliminator stops working, completing the transformer shutdown process.

[0048] In some other embodiments, when the no-load operating voltage on the load side of the main transformer T1 is relatively high, for example, when the no-load operating voltage on the load side of the main transformer T1 is higher than 660V, an exciting transformer T2 is added to the output end of the AC filter 4. The exciting transformer T2 is used to boost the output of the AC filter 4 so that the voltage output by the overvoltage eliminator can reach the rated exciting voltage of the main transformer T1. As Figure 2 shown, the overvoltage eliminator further includes an exciting transformer T2 arranged between the output switch K1 and the output terminal circuit breaker K2. The overvoltage eliminator delivers electrical energy to the load side of the main transformer T1 through the exciting transformer T2. The low-voltage side of the exciting transformer T2 is connected to one end of the output switch K1 far from the AC filter 4, and the high-voltage side of the exciting transformer T2 is connected to one end of the output terminal circuit breaker K2 far from the main transformer T1. The load side of the main transformer T1 is simultaneously connected to one end of the output terminal circuit breaker K2 far from the exciting transformer T2 and one end of the load side circuit breaker K3. The other end of the load side circuit breaker K3 is connected to the load system. The power supply side of the main transformer T1 is connected to one end of the system-side circuit breaker K4, and the other end of the system-side circuit breaker K4 is connected to the power grid system and the modulation wave signal input end of the control module 1. The control coil of the system-side circuit breaker K4 is connected to the control signal output end of the control module 1.

[0049] When the rated excitation voltage of the main transformer T1 is relatively high, when the main transformer T1 is disconnected from the system, the main transformer T1 is in an unloaded operation state. Since the output terminal of the AC filter 4 is connected to the load side of the main transformer T1 through the AC fuse FU1, the output switch K1, the excitation transformer T2, and the output terminal circuit breaker K2 in sequence, under the control of the control module 1, the control module 1 controls the inverter module 3 to use the system voltage on the power supply side of the main transformer T1 as the modulation wave, and according to the phase difference between the power supply side and the load side of the main transformer T1, as well as the phase difference between the high-voltage side and the low-voltage side of the excitation transformer T2, controls the operation of the inverter module 3 to make the voltage output by the excitation transformer T2 have the same phase and amplitude as the no-load voltage on the load side of the main transformer T1. At this time, the two power supplies are connected to the grid through the main transformer coil. When the system-side circuit breaker trips, the no-load transformer overvoltage eliminator with a load transformer is completed to operate, and the excitation current of the transformer is continuously provided by the no-load transformer overvoltage eliminator; subsequently, under the control of the main control system, the amplitude of the output voltage of the overvoltage eliminator is gradually reduced until the amplitude of the output voltage of the overvoltage eliminator is reduced to 0, and the no-load transformer overvoltage eliminator stops working, completing the process of transformer shutdown.

[0050] The principle of the present utility model is described as follows:

[0051] When the main transformer T1 is in an unloaded operation state and the system-side circuit breaker K4 located on the power supply side of the main transformer T1 is tripped, first, the rectification module rectifies the excitation power supply. After the voltage across the DC capacitor C reaches the rated voltage, the bypass DC relay K, the output switch K1, and the output terminal circuit breaker K2 are closed in sequence; subsequently, the control module 1 controls the inverter module 3 to use the grid system voltage on the power supply side of the main transformer T1 as the modulation wave, and according to the phase difference between the power supply side and the load side of the main transformer T1, controls the operation of the inverter module 3 to make the voltage output by the overvoltage eliminator the same as the no-load voltage on the load side of the unloaded main transformer T1. At this time, the inverter module 3 operates with open pulses, and the two power supplies (the grid system and the excitation power supply) are connected to the grid through the main transformer T1. The overvoltage eliminator operates with the load of the main transformer T1, and the excitation current of the main transformer T1 is jointly provided by the overvoltage eliminator and the grid system; subsequently, the system-side circuit breaker K4 is tripped. After the system-side circuit breaker K4 is tripped, under the control of the control module 1, the amplitude of the output voltage of the overvoltage eliminator is gradually reduced until the amplitude of the output voltage of the overvoltage eliminator is reduced to 0, and then the control module 1 controls the overvoltage eliminator to stop working, and the shutdown of the main transformer T1 is completed. Then, the output switch K1 and the output terminal circuit breaker K2 are tripped.

[0052] In the above process, since the voltage on the load side of the main transformer T1 is continuously provided by the overvoltage eliminator when the system-side circuit breaker K4 is disconnected, no cut-off overvoltage will be generated when the system-side circuit breaker K4 is tripped.

[0053] For transformers that need to operate under frequent switching and high voltage due to the operating environment, the overvoltage eliminator provided by the present invention can eliminate the chopped-wave overvoltage generated when an unloaded transformer is switched off, which can greatly improve the safety factor of the transformer. The overvoltage eliminator for unloaded transformers of the present invention is also suitable for application environments such as single-phase transformers.

[0054] Example 1:

[0055] The overvoltage eliminator includes a control module 1, a rectification module 2, an inversion module 3, and an AC filter 4. The AC side of the rectification module 2 is used to connect to the excitation power supply. The DC side of the rectification module 2 is connected to the DC side of the inversion module 3. The AC side of the inversion module 3 is connected to the input end of the AC filter 4. The output end of the AC filter 4 is used to output an AC voltage to the load side of the main transformer T1. The control ends of the rectification module 2 and the inversion module 3 are both connected to the control signal output end of the control module 1. The voltage signal input end of the control module 1 is connected to the output end of the AC filter 4. The modulation wave signal input end of the control module 1 is used to receive the voltage signal on the power supply side of the main transformer T1. A bypass DC relay K, a charging resistor R, and a DC capacitor C are arranged between the rectification module 2 and the inversion module 3. One end of the DC capacitor C is connected to the negative pole of the DC side of the inversion module 3 and the negative pole of the DC side of the rectification module 2. The other end of the DC capacitor C is connected to the positive pole of the DC side of the inversion module 3, one end of the charging resistor R, and one end of the bypass DC relay K. The other end of the charging resistor R and the other end of the bypass DC relay K are connected to the positive pole of the DC side of the rectification module 2. The control coil of the bypass DC relay K is connected to the control signal output end of the control module 1. A DC fuse FU2 is arranged at the positive pole of the DC side of the rectification module 2. An AC fuse FU1 is arranged at the output end of the AC filter 4. Both the rectification module 2 and the inversion module 3 include multiple groups of high-power power electronic devices and a PWM drive circuit. The control signal output end of the control module 1 is connected to the PWM drive circuits of the rectification module 2 and the inversion module 3. The modulation wave signal input end of the control module 1 is connected to the power grid system through a voltage transformer PT. The overvoltage eliminator also includes an output switch K1 and an output circuit breaker K2. The output end of the AC filter 4 is connected to one end of the output switch K1. The other end of the output switch K1 is connected to one end of the output circuit breaker K2. The other end of the output circuit breaker K2 is used to connect to the load side of the transformer T1. The control coils of the output switch K1 and the output circuit breaker K2 are both connected to the control signal output end of the control module 1.

[0056] Example 2:

[0057] Example 2 is basically the same as Example 1, and the difference is as follows:

[0058] The load side of the main transformer T1 is simultaneously connected to one end of the output breaker K2, the remote output switch K1, and one end of the load side breaker K3. The other end of the load side breaker K3 is connected to the load system. The power supply side of the main transformer T1 is connected to one end of the system side breaker K4, and the other end of the system side breaker K4 is connected to the power grid system. The control coil of the system side breaker K4 is connected to the control signal output end of the control module 1. The output breaker K2 is a low-voltage molded case breaker.

[0059] Embodiment 3:

[0060] Embodiment 3 is basically the same as Embodiment 1, except that:

[0061] The overvoltage eliminator further includes an excitation transformer T2 disposed between the output switch K1 and the output breaker K2. The low-voltage side of the excitation transformer T2 is connected to one end of the remote AC filter 4 of the output switch K1, and the high-voltage side of the excitation transformer T2 is connected to one end of the remote main transformer T1 of the output breaker K2.

[0062] The load side of the main transformer T1 is simultaneously connected to one end of the remote excitation transformer T2 of the output breaker K2 and one end of the load side breaker K3. The other end of the load side breaker K3 is connected to the load system. The power supply side of the main transformer T1 is connected to one end of the system side breaker K4, and the other end of the system side breaker K4 is connected to the power grid system. The control coil of the system side breaker K4 is connected to the control signal output end of the control module 1.

[0063] The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. Any equivalent modification or change made by those of ordinary skill in the art according to the disclosure of the present invention shall be included in the protection scope recorded in the claims.

Claims

1. A transformer opening overvoltage eliminator, characterized in that: The overvoltage eliminator includes a control module (1), a rectification module (2), an inversion module (3), and an AC filter (4). The AC side of the rectification module (2) is used to connect to the excitation power supply. The DC side of the rectification module (2) is connected to the DC side of the inversion module (3). The AC side of the inversion module (3) is connected to the input end of the AC filter (4). The output end of the AC filter (4) is used to output an AC voltage to the load side of the main transformer (T1); The control ends of the rectification module (2) and the inversion module (3) are both connected to the control signal output end of the control module (1). The voltage signal input end of the control module (1) is connected to the output end of the AC filter (4). The modulation wave signal input end of the control module (1) is used to receive the voltage signal of the power supply side of the main transformer (T1).

2. The transformer opening overvoltage eliminator according to claim 1, characterized in that: A bypass DC relay (K), a charging resistor (R), and a DC capacitor (C) are arranged between the rectification module (2) and the inversion module (3). One end of the DC capacitor (C) is connected to the negative pole of the DC side of the inversion module (3) and the negative pole of the DC side of the rectification module (2). The other end of the DC capacitor (C) is connected to the positive pole of the DC side of the inversion module (3), one end of the charging resistor (R), and one end of the bypass DC relay (K). The other end of the charging resistor (R) and the other end of the bypass DC relay (K) are connected to the positive pole of the DC side of the rectification module (2). The control coil of the bypass DC relay (K) is connected to the control signal output end of the control module (1).

3. The transformer opening overvoltage eliminator according to claim 2, characterized in that: A DC fuse (FU2) is arranged at the positive pole of the DC side of the rectification module (2); An AC fuse (FU1) is arranged at the output end of the AC filter (4).

4. The transformer opening overvoltage eliminator according to claim 1, characterized in that: Both the rectification module (2) and the inversion module (3) include multiple groups of high-power power electronic devices and a PWM drive circuit; The control signal output end of the control module (1) is connected to the PWM drive circuit of the rectification module (2) and the PWM drive circuit of the inversion module (3).

5. The transformer opening overvoltage eliminator according to claim 1, characterized in that: The modulation wave signal input end of the control module (1) is connected to the power grid system through a voltage transformer (PT).

6. The transformer opening overvoltage eliminator according to any one of claims 1-5, characterized in that: The overvoltage eliminator further includes an output switch (K1) and an output circuit breaker (K2). The output end of the AC filter (4) is connected to one end of the output switch (K1). The other end of the output switch (K1) is connected to one end of the output circuit breaker (K2). The other end of the output circuit breaker (K2) is used to connect to the load side of the main transformer (T1); The control coil of the output switch (K1) and the control coil of the output terminal circuit breaker (K2) are both connected to the control signal output terminal of the control module (1).

7. The overvoltage eliminator for transformer opening according to claim 6, characterized in that: The load side of the main transformer (T1) is simultaneously connected to one end of the output terminal circuit breaker (K2), the far output switch (K1), and one end of the load side circuit breaker (K3). The other end of the load side circuit breaker (K3) is connected to the load system. The power supply side of the main transformer (T1) is connected to one end of the system side circuit breaker (K4), and the other end of the system side circuit breaker (K4) is connected to the power grid system; The control coil of the system side circuit breaker (K4) is connected to the control signal output terminal of the control module (1).

8. The overvoltage eliminator for transformer opening according to claim 7, characterized in that: The output terminal circuit breaker (K2) is a low-voltage molded case circuit breaker.

9. The overvoltage eliminator for transformer opening according to claim 6, characterized in that: The overvoltage eliminator further includes an excitation transformer (T2) disposed between the output switch (K1) and the output terminal circuit breaker (K2). The low-voltage side of the excitation transformer (T2) is connected to one end of the far AC filter (4) of the output switch (K1), and the high-voltage side of the excitation transformer (T2) is connected to one end of the far main transformer (T1) of the output terminal circuit breaker (K2).

10. The overvoltage eliminator for transformer opening according to claim 9, characterized in that: The load side of the main transformer (T1) is simultaneously connected to one end of the output terminal circuit breaker (K2), the far excitation transformer (T2), and one end of the load side circuit breaker (K3). The other end of the load side circuit breaker (K3) is connected to the load system. The power supply side of the main transformer (T1) is connected to one end of the system side circuit breaker (K4), and the other end of the system side circuit breaker (K4) is connected to the power grid system; The control coil of the system side circuit breaker (K4) is connected to the control signal output terminal of the control module (1).

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