CN221709432U - Device for preventing transformer from returning power and power transmission system - Google Patents

Abstract

The utility model discloses a device and a power transmission system for preventing transformers from back-feeding, which relates to the field of electrical automation. A controller, a first relay, a second relay, a third relay and a fourth relay are provided. When the first transformer or the second transformer needs to be shut down, that is, when the first grounding knife or the second grounding knife corresponding to the first transformer or the second transformer is closed, the controller controls the coil of the first relay or the second relay to be energized, and then controls the first low-voltage circuit breaker or the second low-voltage circuit breaker to be disconnected, so as to prevent the back-feeding problem caused by the low-voltage side of the other transformer being energized due to one of the low-voltage circuit breakers not being disconnected. In addition, when the first transformer or the second transformer needs to be operated, the controller controls the coil of the third relay or the fourth relay to be energized, and then controls the first low-voltage circuit breaker or the second low-voltage circuit breaker corresponding to the first transformer or the second transformer to be closed, so as to prevent the back-feeding problem from occurring.

Description

A device for preventing transformer from back-transmitting power and a power transmission system

Technical Field

The utility model relates to the field of electrical automation, in particular to a device for preventing transformer from back-transmitting power and a power transmission system.

Background Art

With the development of science and technology, in order to maintain the symmetry of the operating load of factory equipment during operation, two transformers are often operated in parallel. The connection relationship of the transformer during operation is roughly that the power supply, high-voltage cabinet, transformer, circuit breaker, and load are connected in sequence. In addition, the circuit breakers at the output ends of the two parallel-operating transformers are connected through a busbar circuit breaker, and each high-voltage cabinet is composed of a vacuum circuit breaker and a high-voltage grounding knife.

For step-down transformers, when two step-down transformers are operated in parallel, the power supply system including two step-down transformers is shown in Figure 1. If one of the step-down transformers fails and needs to be cut out for maintenance or other reasons require one of them to be withdrawn, it is necessary to perform electrical isolation on the high-voltage cabinet of the withdrawn step-down transformer, even if the circuit breaker in the high-voltage cabinet is in the separated position, and close the grounding knife in the high-voltage cabinet. Since the two step-down transformers are in parallel operation mode, the low-voltage side circuit breakers and the low-voltage side bus tie circuit breakers of the two step-down transformers are all in the closed state. When one of the step-down transformers is transmitting power, the low-voltage end of the other step-down transformer that is not in operation will be energized. At this time, the high-voltage end of the step-down transformer that is not in operation will also be energized due to its own windings, and then become a step-up transformer, causing the step-down transformer in operation to be grounded short-circuited and tripped. In severe cases, it may cause internal faults in the step-down transformer in operation. However, in the prior art, it is impossible to solve the problem of power return caused by the sudden withdrawal of one of the step-down transformers when two step-down transformers are in parallel operation.

Utility Model Content

The utility model aims to provide a device for preventing transformer backfeed and a power transmission system, which is provided with a controller, a first relay, a second relay, a third relay and a fourth relay, and solves the backfeed problem caused by the sudden shutdown of one of the transformers when two transformers are running in parallel, and the backfeed problem caused by the sudden switching from shutdown to operation of the other transformer when only one of the two transformers is running.

In order to solve the above technical problems, the utility model provides a device for preventing transformer reverse power transmission, comprising:

a first relay, wherein the coil of the first relay is connected to the controller to be energized according to the control of the controller, and the contacts of the first relay are respectively connected to the AC power supply and the opening coil of the first low-voltage circuit breaker, and is used to close when the coil of the first relay is energized to control the opening coil of the first low-voltage circuit breaker to be energized; wherein the high-voltage side of the first transformer is connected to the first high-voltage cabinet, and the low-voltage side is connected to the bus tie circuit breaker through the contacts of the first low-voltage circuit breaker, and is used to disconnect from the second transformer when the opening coil of the first low-voltage circuit breaker is energized;

a second relay, wherein the coil of the second relay is connected to the controller to be energized according to the control of the controller, and the contacts of the second relay are respectively connected to the AC power supply and the opening coil of the second low-voltage circuit breaker, and is used to close when the coil of the second relay is energized to control the opening coil of the second low-voltage circuit breaker to be energized; the high-voltage side of the second transformer is connected to the second high-voltage cabinet, and the low-voltage side is connected to the bus tie circuit breaker through the contacts of the second low-voltage circuit breaker, and is used to disconnect from the first transformer when the opening coil of the second low-voltage circuit breaker is energized;

a third relay, wherein the coil of the third relay is connected to the controller to be energized according to the control of the controller, and the contacts of the third relay are respectively connected to the AC power supply and the closing coil of the first low-voltage circuit breaker, and is used to close when the coil of the third relay is energized to control the closing coil of the first low-voltage circuit breaker to be energized; wherein the high-voltage side of the first transformer is connected to the first high-voltage cabinet, and the low-voltage side is connected to the bus tie circuit breaker through the contacts of the first low-voltage circuit breaker, and is used to be connected to the second transformer when the closing coil of the first low-voltage circuit breaker is energized;

a fourth relay, wherein the coil of the fourth relay is connected to the controller to be energized according to the control of the controller, and the contacts of the fourth relay are respectively connected to the AC power supply and the closing coil of the second low-voltage circuit breaker, and is used to close when the coil of the fourth relay is energized to control the closing coil of the second low-voltage circuit breaker to be energized; the high-voltage side of the second transformer is connected to the second high-voltage cabinet, and the low-voltage side is connected to the bus tie circuit breaker through the contacts of the second low-voltage circuit breaker, and is used to be connected to the first transformer when the closing coil of the second low-voltage circuit breaker is energized;

The controller is used to control the coil of the first relay to be energized or the coil of the second relay to be energized when a signal indicating that the auxiliary normally open contact of the first grounding switch is closed or a signal indicating that the auxiliary normally open contact of the second grounding switch is closed is detected, and to control the coil of the third relay to be energized or the coil of the fourth relay to be energized when a signal indicating that the auxiliary normally open contact of the first vacuum circuit breaker is closed or a signal indicating that the auxiliary normally open contact of the second vacuum circuit breaker is closed is detected.

Optionally, also include:

A first resistor and a first inductive device connected in series with the first resistor, wherein the input end of the first resistor is connected to a DC power supply through the first inductive device and the first grounding switch auxiliary normally open contact, and the output end is connected to the controller.

Optionally, also include:

A second resistor and a second inductive device connected in series with the second resistor, the input end of the second resistor is connected to a DC power supply through the second inductive device and the second grounding switch auxiliary normally open contact, and the output end is connected to the controller.

Optionally, also include:

A third resistor and a third inductive device connected in series with the third resistor, wherein the third resistor and the third inductive device are connected in series with a DC power supply through an auxiliary normally open contact of the first vacuum circuit breaker and an output normally open contact of a first current relay.

Optionally, also include:

A fourth resistor and a fourth inductive device connected in series with the fourth resistor, wherein the fourth resistor and the fourth inductive device are connected in series with a DC power supply through an auxiliary normally open contact of the second vacuum circuit breaker and an output normally open contact of a second current relay.

Optionally, also include:

A first current control relay, wherein the coil of the first current control relay is connected to the secondary current side of the current transformer in the first high-voltage cabinet, and is used to be energized when a no-load current is detected after the first transformer is energized, and the output auxiliary normally open contacts of the first current control relay are respectively connected to the auxiliary normally open contacts of the AC power supply and the first vacuum circuit breaker, and are used to be closed when the coil of the first current control relay is energized.

Optionally, also include:

A second current control relay, the coil of the second current control relay is connected to the secondary side current of the current transformer in the second high-voltage cabinet, and is used to be energized when the no-load current is detected after the second transformer is energized, and the output auxiliary normally open contacts of the second current control relay are respectively connected to the auxiliary normally open contacts of the AC power supply and the second vacuum circuit breaker, and are used to be closed when the coil of the second current control relay is energized.

In order to solve the above technical problems, the utility model also provides a power transmission system, including the device for preventing transformer reverse power transmission as described above, a first transformer and a second transformer, wherein the device for preventing transformer reverse power transmission is connected to the first transformer and the second transformer respectively.

Optionally, also include:

A shell, wherein the transformer reverse power transmission prevention device, the first transformer and the second transformer are arranged inside the shell.

The purpose of the utility model is to provide a device and a power transmission system for preventing transformer backfeeding, which are provided with a controller, a first relay and a second relay. When the first transformer needs to be shut down, that is, when the first grounding knife corresponding to the first transformer is closed or the first vacuum circuit breaker is disconnected or the first transformer stops running, when the first current control relay cannot detect the current, the controller will control the coil of the first relay to be energized, and then control the opening coil of the first low-voltage circuit breaker corresponding to the first transformer to be energized, that is, the first low-voltage circuit breaker is disconnected, so as to prevent the first transformer from backfeeding due to the first low-voltage circuit breaker not being disconnected, which makes the low-voltage side of the second transformer energized. Conversely, when the second transformer needs to be shut down, the controller will control the coil of the second relay to be energized, so as to control the opening coil of the second low-voltage circuit breaker to be energized, so as to disconnect the second low-voltage circuit breaker, so as to prevent the second transformer from backfeeding due to the second low-voltage circuit breaker not being disconnected, which makes the low-voltage side of the first transformer energized.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

FIG1 is a schematic structural diagram of a parallel operation transformer provided by the utility model;

FIG2 is a schematic structural diagram of a device for preventing reverse power transmission from a transformer provided by the utility model;

FIG3 is a schematic diagram of a controller for controlling input and output provided by the present invention;

FIG. 4 is a schematic diagram of another controller for controlling input and output provided by the present invention.

DETAILED DESCRIPTION

The core of the utility model is to provide a device and a power transmission system for preventing transformer backfeed, which are provided with a controller, a first relay, a second relay, a third relay and a fourth relay, so as to solve the backfeed problem caused by the sudden shutdown of one of the two transformers when the two transformers are running in parallel, and the backfeed problem caused by the sudden switching from shutdown to operation of the other transformer when only one of the two transformers is running.

In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

Please refer to FIG. 2 , which is a schematic diagram of the structure of a device for preventing reverse power transmission from a transformer provided by the utility model. The device comprises:

A first relay 1, wherein the coil of the first relay 1 is connected to the controller 5 to be energized according to the control of the controller 5, and the contacts of the first relay 1 are respectively connected to the AC power supply and the opening coil of the first low-voltage circuit breaker, and are used to close when the coil of the first relay 1 is energized to control the opening coil of the first low-voltage circuit breaker to be energized; wherein the high-voltage side of the first transformer is connected to the first high-voltage cabinet, and the low-voltage side is connected to the bus tie circuit breaker through the contacts of the first low-voltage circuit breaker, and is used to disconnect the connection with the second transformer when the opening coil of the first low-voltage circuit breaker is energized;

A second relay 2, the coil of the second relay 2 is connected to the controller 5 to be energized according to the control of the controller 5, and the contacts of the second relay 2 are respectively connected to the AC power supply and the opening coil of the second low-voltage circuit breaker, and are used to close when the coil of the second relay 2 is energized to control the opening coil of the second low-voltage circuit breaker to be energized; the high-voltage side of the second transformer is connected to the second high-voltage cabinet, and the low-voltage side is connected to the bus tie circuit breaker through the contacts of the second low-voltage circuit breaker, and is used to disconnect from the first transformer when the opening coil of the second low-voltage circuit breaker is energized;

a third relay 3, the coil of the third relay 3 is connected to the controller 5 to be energized according to the control of the controller 5, the contacts of the third relay 3 are respectively connected to the AC power supply and the closing coil of the first low-voltage circuit breaker, and is used to close when the coil of the third relay 3 is energized to control the closing coil of the first low-voltage circuit breaker to be energized; wherein the high-voltage side of the first transformer is connected to the first high-voltage cabinet, and the low-voltage side is connected to the bus tie circuit breaker through the contacts of the first low-voltage circuit breaker, and is used to be connected to the second transformer when the closing coil of the first low-voltage circuit breaker is energized;

A fourth relay 4, the coil of the fourth relay 4 is connected to the controller 5 to be energized according to the control of the controller 5, and the contacts of the fourth relay 4 are respectively connected to the AC power supply and the closing coil of the second low-voltage circuit breaker, and are used to close when the coil of the fourth relay 4 is energized to control the closing coil of the second low-voltage circuit breaker to be energized; the high-voltage side of the second transformer is connected to the second high-voltage cabinet, and the low-voltage side is connected to the bus tie circuit breaker through the contacts of the second low-voltage circuit breaker, and is used to be connected to the first transformer when the closing coil of the second low-voltage circuit breaker is energized;

The controller 5 is used for controlling the coil of the first relay 1 to be energized or the coil of the second relay 2 to be energized when a signal indicating the closure of the auxiliary normally open contact of the first grounding switch or a signal indicating the closure of the auxiliary normally open contact of the second grounding switch is detected, and for controlling the coil of the third relay 3 to be energized or the coil of the fourth relay 4 to be energized when a signal indicating the closure of the auxiliary normally open contact of the first vacuum circuit breaker or a signal indicating the closure of the auxiliary normally open contact of the second vacuum circuit breaker is detected.

In the present invention, because the corresponding first low-voltage circuit breaker, the second low-voltage circuit breaker and the intermediate connected bus tie circuit breaker are not disconnected during the parallel operation of two transformers (the first transformer and the second transformer), when the normally open contact of the grounding knife corresponding to one transformer is closed (the grounding knife is grounded), there will be a problem that the transformer in operation returns power to the transformer that is not in operation. Therefore, in this solution, a controller 5, a first relay 1 and a second relay 2 are provided. When the auxiliary normally open contact of the first grounding knife corresponding to the first transformer is closed, the controller 5 controls the coil of the first relay 1 to be energized, thereby closing the contact of the first relay 1 and the first low-voltage circuit breaker is disconnected. The opening coil of the high-voltage circuit breaker is energized, thereby disconnecting the first low-voltage circuit breaker corresponding to the first transformer, to prevent the low-voltage side of the second transformer from being energized due to the first low-voltage circuit breaker not being disconnected, thereby causing the first transformer to back-supply power. In addition, when the auxiliary normally open contact of the second grounding knife corresponding to the second transformer is closed, the controller 5 controls the coil of the second relay 2 to be energized, thereby closing the contacts of the second relay 2, and energizing the opening coil of the second low-voltage circuit breaker, thereby disconnecting the second low-voltage circuit breaker corresponding to the second transformer, to prevent the low-voltage side of the second transformer from being energized due to the second low-voltage circuit breaker not being disconnected, thereby causing the second transformer to back-supply power. In addition, when only one of the two transformers (the first transformer and the second transformer) is in operation, because the corresponding first low-voltage circuit breaker, the second low-voltage circuit breaker and the intermediate connected bus tie circuit breaker are not disconnected, when the auxiliary normally open contact of the first vacuum circuit breaker corresponding to the other transformer is suddenly closed, there will be a problem of the operating transformer returning power to the non-operating transformer. At this time, the controller 5, the third relay 3 and the fourth relay 4 provided in the present application can control the coil of the third relay 3 to be energized or the coil of the fourth relay 4 to be energized when the controller 5 detects a signal representing the closure of the auxiliary normally open contact of the first vacuum circuit breaker or a signal representing the closure of the auxiliary normally open contact of the second vacuum circuit breaker, thereby associating the closing of the first low-voltage circuit breaker and the second low-voltage circuit breaker with the closing of the corresponding vacuum circuit breaker, thereby solving the problem of returning power.

It should be noted that when factory equipment is running, due to the asymmetric operating load, the transformer load will be unbalanced, some transformers are heavily loaded, and some transformers are lightly loaded, which is not conducive to the economic operation of the transformer. At this time, it is necessary to run two transformers with the same parameter type in parallel to balance the load of the two transformers and make the transformers run more economically.

It should also be noted that the problem of the operating transformer returning power to the transformer that has just switched to the operating state through the main coupling circuit breaker and the second low-voltage circuit breaker has been solved, because a large excitation surge current will be generated in this process, the excitation surge current has a long decay time, and generates a large electric force, and also has a great impact on the mechanical strength of the transformer. When the vacuum circuit breaker in the high-voltage cabinet corresponding to the transformer is closed, the high-voltage cabinet microcomputer protection or the high-voltage incoming line cabinet microcomputer protection will malfunction due to the inrush current, causing the system to trip and power outage.

It should also be noted that the problem to be solved by this application is actually that when two transformers are running in parallel, if one of the transformers fails and needs to be cut out for maintenance or other reasons require one of them to be withdrawn, or when power is restored after a sudden power outage. Since the two transformers are in parallel operation mode, the low-voltage side circuit breakers and the low-voltage side busbar circuit breakers of the two transformers are all in a closed state. When one of the transformers is powered on, the low-voltage end of the other transformer that is not running will be energized. At this time, the transformer that is not running will become a step-up transformer, making the high-voltage end energized, and the power will be transmitted to the lower end of the circuit breaker in the high-voltage cabinet through the cable. In the first case, if it is necessary to perform electrical isolation and close the grounding switch on the high-voltage cabinet of the non-operating transformer, the three-phase voltage of the reverse-powered transformer will be grounded, causing the other operating transformer to trip. In severe cases, it may cause internal faults in the reverse-powered transformer. In the second case, if two transformers need to operate in parallel, and the other non-operating transformer switches from exit to operation, the high-voltage cabinet circuit breaker of the non-operating transformer is closed. At this time, the system voltage will form a short circuit with the reverse voltage on the low-voltage side, and the short-circuit current will cause the system high-voltage incoming line cabinet to trip.

This embodiment provides a device for preventing transformer backflow, which includes a controller 5, a first relay 1, a second relay 2, a third relay 3 and a fourth relay 4. When the first transformer or the second transformer needs to be shut down, that is, when the first grounding knife or the second grounding knife corresponding to the first transformer or the second transformer is closed, the controller 5 controls the coil of the first relay 1 or the second relay 2 to be energized, and then controls the first low-voltage circuit breaker or the second low-voltage circuit breaker to be disconnected, so as to prevent the backflow problem caused by the low-voltage side of the other transformer being energized due to one of the low-voltage circuit breakers not being disconnected. In addition, when the first transformer or the second transformer needs to be operated, the controller 5 controls the coil of the third relay 3 or the fourth relay 4 to be energized, and then controls the first low-voltage circuit breaker or the second low-voltage circuit breaker corresponding to the first transformer or the second transformer to be closed, so as to prevent the backflow problem from occurring.

As an optional embodiment, it also includes:

The first resistor and the first inductive device connected in series with the first resistor, the input end of the first resistor is connected to the DC power supply through the first inductive device and the first grounding switch auxiliary normally open contact, and the output end is connected to the controller 5.

In the utility model, the device for preventing the transformer from back-feeding power also includes a first resistor and a first inductive device connected in series with the first resistor. The first resistor is connected to the DC power supply through the first inductive device and the first grounding knife auxiliary normally open contact, and is energized after the first grounding knife auxiliary normally open contact is closed, and plays a role in current limiting. The controller 5 detects the energization of the first inductive device, thereby controlling the energization of the coil of the first relay 1, and then controlling the energization of the opening coil of the first low-voltage circuit breaker corresponding to the first transformer, thereby improving the accuracy of the solution.

It should be noted that, in practical applications, the first inductive device is a component for detecting voltage, which can be expressed as a “potential”.

As an optional embodiment, it also includes:

The second resistor and the second inductive device connected in series with the second resistor, the input end of the second resistor is connected to the DC power supply through the second inductive device and the second grounding switch auxiliary normally open contact, and the output end is connected to the controller 5.

In the utility model, the device for preventing the transformer from back-feeding power also includes a second resistor and a second inductive device connected in series with the second resistor. The second resistor is connected to the DC power supply through the second inductive device and the second grounding knife auxiliary normally open contact, and is energized after the second grounding knife auxiliary normally open contact is closed, and plays a role in current limiting. The controller 5 detects the energization of the second inductive device, thereby controlling the energization of the coil of the second relay 1, and then controlling the energization of the opening coil of the second low-voltage circuit breaker corresponding to the second transformer, thereby improving the accuracy of the solution.

As an optional embodiment, it also includes:

The third resistor and the third inductive device connected in series with the third resistor are connected in series with the DC power supply through the auxiliary normally open contact of the first vacuum circuit breaker and the output normally open contact of the first current relay.

In the utility model, the device for preventing the transformer from back-transmitting power also includes a third resistor and a third inductive device. The third resistor is connected to the DC power supply through the third inductive device and the auxiliary normally open contact of the first vacuum circuit breaker. When the auxiliary normally open contact of the first vacuum circuit breaker is closed, the third resistor is energized and plays a role in current limiting. At this time, the controller 5 can detect the signal indicating the closing of the auxiliary normally open contact of the first vacuum circuit breaker by detecting the change of the voltage on the third inductive device and control the coil of the third relay 3 to be energized, thereby controlling the closing coil of the first low-voltage circuit breaker corresponding to the first transformer to be energized, thereby improving the accuracy of the scheme.

As an optional embodiment, it also includes:

A fourth resistor and a fourth inductive device connected in series with the fourth resistor, the fourth resistor and the fourth inductive device are connected in series with the DC power supply through the auxiliary normally open contact of the second vacuum circuit breaker and the output normally open contact of the second current relay.

In the utility model, the device for preventing the transformer from back-transmitting power also includes a fourth resistor and a fourth inductive device. The fourth resistor is connected to the DC power supply through the fourth inductive device and the auxiliary normally open contact of the second vacuum circuit breaker. When the auxiliary normally open contact of the second vacuum circuit breaker is closed, the fourth resistor is energized and plays a role in current limiting. At this time, the controller 5 can detect the signal indicating the closing of the auxiliary normally open contact of the second vacuum circuit breaker by detecting the change in the voltage on the fourth inductive device and control the coil of the fourth relay 3 to be energized, thereby controlling the closing coil of the second low-voltage circuit breaker corresponding to the second transformer to be energized, thereby improving the accuracy of the solution.

As an optional embodiment, it also includes:

The first current control relay, the coil of the first current control relay is connected to the secondary current side of the current transformer in the first high-voltage cabinet, and is used to be energized when the no-load current is detected after the first transformer is energized. The output auxiliary normally open contacts of the first current control relay are respectively connected to the auxiliary normally open contacts of the AC power supply and the first vacuum circuit breaker, and are used to be closed when the coil of the first current control relay is energized.

In the utility model, the device for preventing transformer back-transmission of power also includes a first current control relay. When the first current control relay detects the no-load current after the first transformer is energized, the coil of the first current relay will be energized and its own contacts will be closed, so that the operation of closing the first low-voltage circuit breaker is performed after the corresponding first vacuum circuit breaker is closed, thereby improving the reliability of the solution.

It should be noted that in actual applications, a current relay is installed in each transformer high-voltage cabinet. The setting action current of the current relay is set to the transformer no-load current, and the current relay has a passive contact. The purpose of setting the current relay is to prevent the low-voltage circuit breaker from closing when the vacuum circuit breaker of the high-voltage cabinet is in the test position, which will also cause the low-voltage side of the transformer to be energized and the transformer to reverse power.

As an optional embodiment, it also includes:

The second current control relay, the coil of the second current control relay is connected to the secondary side current of the current transformer in the second high-voltage cabinet, and is used to be energized when the no-load current is detected after the second transformer is energized. The output auxiliary normally open contacts of the second current control relay are respectively connected to the auxiliary normally open contacts of the AC power supply and the second vacuum circuit breaker, and are used to close when the coil of the second current control relay is energized.

In the utility model, the device for preventing transformer back-transmission of power also includes a second current control relay. When the second current control relay detects the no-load current after the second transformer is energized, the coil of the second current relay will be energized and its own contacts will be closed, so that the operation of closing the second low-voltage circuit breaker is performed after the corresponding second vacuum circuit breaker is closed, thereby improving the reliability of the solution.

It should be noted that the normally open point of the auxiliary micro switch of the high-voltage grounding switch in each transformer high-voltage cabinet is connected to the opening point 1 (i.e., the first resistor and potential) or the opening point 2 (i.e., the second resistor and potential) of the respective microcomputer protection device, and the auxiliary normally open contact of the vacuum circuit breaker in each transformer high-voltage cabinet is connected in series with the normally open contact of the current control relay and then connected to the opening point 3 (i.e., the third resistor and potential) or the opening point 4 (i.e., the fourth resistor and potential) of the respective microcomputer protection device, which is realized by processor module 1 and processor module 2 (controller 5), that is, after opening 1 or opening 2 (powered), the first relay 1 is linked to be opened or the second relay 2 is opened, and after opening 3 or opening 4 (powered), the first relay 1 is linked to be opened or the second relay 2 is closed. After opening 1 or opening 2, the opening 1 or opening 2 is linked to be closed, which will solve the short circuit caused by closing the grounding knife in the first case. That is, when the high-voltage earthing knife is closed, the normally open point of the high-voltage earthing knife microswitch changes from normally open to closed. At this time, when the microcomputer protection device receives the input 1 closing signal, output 1 will change from normally open to normally closed, and the low-voltage circuit breaker tripping coil will be energized and trip; after input 3 or input 4 is closed, the linkage opening 3 or output 4 will solve the second situation. When two transformers need to operate in parallel, the other non-operating transformer changes from exit to operation, and the high-voltage cabinet circuit breaker of the non-operating transformer is closed. At this time, the reverse voltage on the low-voltage side will generate a large magnetizing surge current. The microcomputer protection of the transformer cabinet or the microcomputer protection of the high-voltage incoming line cabinet will malfunction due to unavoidable surge current, which will cause the system to trip and power outage. That is, when the high-voltage cabinet vacuum circuit breaker is opened and the current control relay is set to no current, the vacuum circuit breaker auxiliary normally open point and the current control relay action normally open point change from normally open to closed. At this time, the microcomputer protection device receives the input 3 or input 4 closing signal from open to closed, the output 3 or output 4 relay coil is energized, the contacts will change from normally open to normally closed, and the low-voltage circuit breaker tripping coil is energized and trips.

It should also be noted that when two transformers need to be operated in parallel, the low-voltage side circuit breaker of the second transformer can be linked to close when the second transformer is put into use. Specifically, the third and fourth output points 3 and 4 are set in the microcomputer protection, and output points 3 and 4 are connected to the low-voltage circuit breaker closing coil. The input linkage program is set, that is, after input 3 or input 4 is closed, output 3 or output 4 is linked to close. That is, after the vacuum circuit breaker in the high-voltage cabinet is closed, the auxiliary normally open point of the vacuum circuit breaker changes from open to closed, and the passive output normally open point of the current control relay changes from open to closed. After input 3 or input 4 is energized, it is closed. When input 3 or input 4 is energized and closed, it will be linked to output 3 or output 4 to close, and the low-voltage circuit breaker closing coil The circuit breaker is energized and closed, wherein the control of the first relay 1 and the third relay 3 is shown in FIG3 , and the control of the second relay 2 and the fourth relay 4 is shown in FIG4 , and the input 1 and the input 3 are located in the power module 1, and the first relay 1 and the third relay 3 are located in the first high-voltage cabinet microcomputer protection device controller, and are controlled by the processor module 1; the input 2 and the input 4 are located in the power module 2, and the second relay 2 and the fourth relay 4 are located in the second high-voltage cabinet microcomputer protection device controller, and are controlled by the processor module 2.

The utility model also provides a corresponding embodiment of a power transmission system, comprising the above-mentioned device for preventing transformer reverse power transmission, a first transformer and a second transformer, wherein the device for preventing transformer reverse power transmission is connected to the first transformer and the second transformer respectively.

As an optional embodiment, it also includes:

The outer shell includes a device for preventing the transformer from transmitting power in reverse, a first transformer and a second transformer.

The power transmission system provided in this embodiment corresponds to the above-mentioned device, and thus has the same beneficial effects as the above-mentioned device. Therefore, for the embodiments of the power transmission system part, please refer to the description of the embodiments of the device part, which will not be repeated here.

It should be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. A device for preventing reverse power transmission of a transformer, comprising:

the first relay is connected with the controller to obtain electricity according to the control of the controller, and contacts of the first relay are respectively connected with an alternating current power supply and a switching-off coil of a first low-voltage circuit breaker and are used for being closed when the coil of the first relay is obtained to control the switching-off coil of the first low-voltage circuit breaker to obtain electricity; the high-voltage side of the first transformer is connected with the first high-voltage cabinet, and the low-voltage side of the first transformer is connected with the bus-bar circuit breaker through a contact of the first low-voltage circuit breaker and is used for disconnecting the first low-voltage circuit breaker from the second transformer when the breaking coil of the first low-voltage circuit breaker is powered on;

The coil of the second relay is connected with the controller to obtain electricity according to the control of the controller, and the contacts of the second relay are respectively connected with the alternating current power supply and the opening coil of the second low-voltage circuit breaker and are used for being closed when the coil of the second relay is obtained to control the opening coil of the second low-voltage circuit breaker to obtain electricity; the high-voltage side of the second transformer is connected with a second high-voltage cabinet, and the low-voltage side of the second transformer is connected with the female-connection circuit breaker through a contact of the second low-voltage circuit breaker and is used for disconnecting the connection with the first transformer when a breaking coil of the second low-voltage circuit breaker is powered on;

The coil of the third relay is connected with the controller to obtain electricity according to the control of the controller, and the contact of the third relay is respectively connected with the alternating current power supply and the closing coil of the first low-voltage circuit breaker and is used for closing when the coil of the third relay is obtained to obtain electricity so as to control the closing coil of the first low-voltage circuit breaker to obtain electricity; the high-voltage side of the first transformer is connected with the first high-voltage cabinet, and the low-voltage side of the first transformer is connected with the female-connection circuit breaker through a contact of the first low-voltage circuit breaker and is used for being connected with the second transformer when a closing coil of the first low-voltage circuit breaker is powered on;

the coil of the fourth relay is connected with the controller to obtain electricity according to the control of the controller, and the contact of the fourth relay is respectively connected with the alternating current power supply and the closing coil of the second low-voltage circuit breaker and is used for closing when the coil of the fourth relay is obtained to obtain electricity so as to control the closing coil of the second low-voltage circuit breaker to obtain electricity; the high-voltage side of the second transformer is connected with the second high-voltage cabinet, and the low-voltage side of the second transformer is connected with the female-connection circuit breaker through a contact of the second low-voltage circuit breaker and is used for being connected with the first transformer when a closing coil of the second low-voltage circuit breaker is powered on;

The controller is used for controlling the coil of the first relay to be electrified or controlling the coil of the second relay to be electrified when a signal representing that the auxiliary normally open contact of the first grounding knife is closed or a signal representing that the auxiliary normally open contact of the second grounding knife is closed is detected, and controlling the coil of the third relay to be electrified or controlling the coil of the fourth relay to be electrified when a signal representing that the auxiliary normally open contact of the first vacuum circuit breaker is closed or a signal representing that the auxiliary normally open contact of the second vacuum circuit breaker is closed is detected.

2. The device for preventing reverse power transmission of a transformer as claimed in claim 1, further comprising:

The input end of the first resistor is connected with a direct current power supply through the first electric sensing device and the first grounding knife auxiliary normally open contact, and the output end of the first resistor is connected with the controller.

3. The device for preventing reverse power transmission of a transformer as claimed in claim 1, further comprising:

The input end of the second resistor is connected with a direct-current power supply through the second inductance device and the second grounding knife auxiliary normally-open contact, and the output end of the second resistor is connected with the controller.

4. The device for preventing reverse power transmission of a transformer as claimed in claim 1, further comprising:

The third resistor and the third electric sensing device are connected in series with the third resistor, and the third resistor and the third electric sensing device are connected in series with a direct-current power supply through an auxiliary normally-open contact of the first vacuum circuit breaker and a normally-open contact of the first current relay output.

5. The device for preventing reverse power transmission of a transformer as claimed in claim 1, further comprising:

The fourth resistor and the fourth electric sensing device are connected in series with the fourth resistor, and the fourth resistor and the fourth electric sensing device are connected in series with a direct-current power supply through an auxiliary normally-open contact of the second vacuum circuit breaker and an output normally-open contact of the second current relay.

6. The device for preventing reverse power transmission of a transformer as claimed in claim 1, further comprising:

The coil of the first current control relay is connected with the secondary current side of the current transformer in the first high-voltage cabinet and is used for obtaining electricity when no-load current obtained after the first transformer is electrified is detected, and the output auxiliary normally open contact of the first current control relay is respectively connected with the alternating current power supply and the auxiliary normally open contact of the first vacuum circuit breaker and is used for being closed when the coil of the first current control relay is electrified.

7. The transformer reverse power transmission preventing device according to any one of claims 1 to 6, further comprising:

the coil of the second current control relay is in current connection with the secondary side of the current transformer in the second high-voltage cabinet and is used for obtaining electricity when no-load current obtained after the second transformer is detected, and the output auxiliary normally open contact of the second current control relay is respectively connected with the alternating current power supply and the auxiliary normally open contact of the second vacuum circuit breaker and is used for being closed when the coil of the second current control relay is obtained.

8. A power transmission system comprising the device for preventing reverse power transmission of a transformer, a first transformer, and a second transformer according to any one of claims 1 to 7, wherein the device for preventing reverse power transmission of a transformer is connected to the first transformer and the second transformer, respectively.

9. The power transmission system of claim 8, further comprising:

And the shell is internally provided with the device for preventing reverse power transmission of the transformer, the first transformer and the second transformer.