Low-voltage grid-connected cabinet with function of automatic reclosing in case of fault removal

Abstract

The utility model relates to the technical field of electrical cabinets, and particularly discloses a low-voltage grid-connected cabinet with an automatic reclosing function when a fault is removed, which comprises a cabinet body frame, a metering chamber, a circuit breaker chamber, an inlet and outlet cable chamber, a circuit breaker, a relay protection device and a current transformer, the lower end of the circuit breaker is connected with a photovoltaic branch switch or an energy storage side, the upper end of the circuit breaker is connected with a power grid side bus, a power grid side copper bar is provided with a metering transformer, a metering chamber is provided with a bidirectional meter, and a current transformer is arranged at the cable end, away from the grid-connected circuit breaker, of the power grid and the energy storage side. And the circuit breaker is driven to trip according to the current difference value. According to the utility model, the relay protection device is arranged to collect and compare the currents at the two ends, differential protection and circuit breaker tripping are realized according to the current difference value, automatic reclosing can be realized, a watch man does not need to go to the field to carry out manual closing operation, and the convenience and the safety are greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of electrical cabinets, in particular to a low-voltage grid-connected cabinet with an automatic reclosing switch capable of cutting off faults. Background Art

[0002] With the development of social economy and the improvement of environmental awareness, people's demand for clean energy is becoming stronger and stronger, and the application of photovoltaic and energy storage systems is increasing. The application of photovoltaic, energy storage and other systems must be connected to the power grid system when in use. The stability of photovoltaic and energy storage systems is extremely important, otherwise it is easy to have a certain impact on the normal power consumption of the power grid. Once the system fails, the fault must be cut off immediately, and the grid-connected cabinet circuit breaker must be opened. After the fault is eliminated, the grid-connected cabinet circuit breaker can be closed. At present, the grid-connected cabinets on the market only provide short-circuit protection for the load side of the circuit breaker. After the fault is eliminated, manual on-site operation is required to close the circuit breaker. Especially when the grid-connected cabinet is far away, it will cause unnecessary trouble to the engineering personnel, and some specific protections required for photovoltaic and energy storage are not comprehensive enough. Based on this current situation in the market, the applicant decided to carry out the research and development of a low-voltage grid-connected cabinet with automatic reclosing after fault removal. Utility Model Content

[0003] The technical problem to be solved by the utility model is that, in view of the above-mentioned defects of the prior art, a low-voltage grid-connected cabinet with an automatic reclosing switch for cutting off faults is provided. A relay protection device is set to collect the currents at both ends and compare them. Differential protection and circuit breaker tripping are realized according to the current difference. Automatic reclosing can be realized without the need for on-duty personnel to go to the site to perform manual operation to close the switch, which greatly improves convenience and safety.

[0004] In order to solve the above technical problems, the technical solution of the utility model is:

[0005] A low-voltage grid-connected cabinet with an automatic reclosing switch for removing faults, comprising a cabinet frame, a metering room, a circuit breaker room, an incoming and outgoing cable room, a circuit breaker, a relay protection device and a current transformer. The circuit breaker is installed in the circuit breaker room, the lower end of the circuit breaker is connected to a photovoltaic switch or an energy storage side, the upper end of the circuit breaker is connected to a grid-side busbar, a metering transformer is installed on a grid-side copper busbar, a bidirectional meter is provided in the metering room, the current transformer is arranged at the cable end of the grid and the energy storage side away from the grid-connected circuit breaker, the relay protection device collects currents at both ends for comparison, and drives the circuit breaker to trip according to the current difference.

[0006] Preferably, a grid-connected isolating switch, a grid-connected main switch and a plurality of electric operation indicator light buttons are provided at the front end of the cabinet frame, and the metering transformer and photovoltaic sub-switch are provided at the rear end of the cabinet frame.

[0007] Preferably, the metering room, circuit breaker room, incoming and outgoing cable room, circuit breaker, relay protection device and current transformer are all arranged on the cabinet frame.

[0008] Preferably, the relay protection device comprises a relay, a current measurement circuit and a voltage measurement circuit, and the circuit breaker, the current measurement circuit and the voltage measurement circuit are all electrically connected to the relay.

[0009] Preferably, the current transformer is electrically connected to the relay via a current signal loop.

[0010] Preferably, the metering transformer is electrically connected to the relay via an output quantity loop.

[0011] By adopting the above technical scheme, the utility model provides a low-voltage grid-connected cabinet with an automatic reclosing switch for cutting off faults, which has the following beneficial effects: the circuit breaker in the low-voltage grid-connected cabinet is installed in the circuit breaker room, the lower end of the circuit breaker is connected to the photovoltaic sub-switch or the energy storage side, the upper end of the circuit breaker is connected to the busbar on the grid side, the copper bar on the grid side is installed with a metering transformer, the metering room is provided with a bidirectional meter, the current transformer is arranged at the cable end of the grid and the energy storage side away from the grid-connected circuit breaker, the relay protection device collects the current at both ends for comparison, and drives the circuit breaker to trip according to the current difference, and the relay protection device is set to collect the current at both ends and compare, and the current difference is set according to the current difference. The current difference realizes differential protection. When the front and rear currents are inconsistent, the differential protection is activated and the circuit breaker trips. After the fault is restored, the circuit breaker can automatically reclose after the relay protection device is successfully reset. The relay protection device also collects the voltages on both sides of the power grid and the energy storage system at the same time, which can realize voltage and frequency protection of the energy storage system. When it is detected that the voltage or frequency on both sides is inconsistent, the protection can be activated to cut off the energy storage system. After the fault is restored, the voltage or frequency on both sides returns to normal, and the circuit breaker can automatically reclose and restore the energy storage system without the need for on-duty personnel to go to the site for manual operation, which greatly improves the convenience and safety of the low-voltage grid-connected cabinet. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is the front view of the utility model;

[0013] Figure 2 It is a rear view of the utility model;

[0014] Figure 3 It is a cross-sectional view of the utility model;

[0015] Figure 4 It is the electrical schematic diagram of the utility model;

[0016] In the figure, 1-cabinet frame, 2-metering room, 3-circuit breaker room, 4-incoming and outgoing cable room, 5-circuit breaker, 6-relay protection device, 7-current transformer, 8-grid-connected side disconnector, 9-grid-connected side main switch, 10-electrical operation indicator button, 11-metering transformer, 12-photovoltaic sub-switch, 13-relay. DETAILED DESCRIPTION

[0017] The specific implementation methods of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these implementation methods is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each implementation method of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0018] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0019] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0020] like Figure 1-4As shown, the low-voltage grid-connected cabinet with automatic reclosing for fault removal includes a cabinet frame 1, a metering room 2, a circuit breaker room 3, an incoming and outgoing cable room 4, a circuit breaker 5, a relay protection device 6 and a current transformer 7. The circuit breaker 5 is installed in the circuit breaker room 3. The lower end of the circuit breaker 5 is connected to the photovoltaic switch or the energy storage side, and the upper end of the circuit breaker 5 is connected to the grid-side busbar. The grid-side copper bar is equipped with a metering transformer 11. The metering room 2 is provided with a bidirectional meter. The current transformer 7 is arranged at the cable end of the grid and the energy storage side away from the grid-connected circuit breaker. The relay protection device 6 collects the currents at both ends for comparison, and drives the circuit breaker 5 to trip according to the current difference. It can be understood that the relay protection device The device collects the current at both ends and compares them, and implements differential protection based on the current difference. When the currents before and after are inconsistent, the differential protection is activated to trip the circuit breaker. After the fault is restored, the circuit breaker can automatically reclose after the relay protection device is successfully reset. The relay protection device also collects the voltage on both sides of the power grid and the energy storage system at the same time, which can realize voltage and frequency protection of the energy storage system. When it is detected that the voltage or frequency on both sides is inconsistent, the energy storage system is cut off. After the fault is restored, the voltage or frequency on both sides returns to normal, and the circuit breaker automatically recloses to restore the energy storage system without the need for on-duty personnel to go to the site for manual operation and closing, which greatly improves the convenience and safety of the low-voltage grid-connected cabinet.

[0021] Specifically, the front end of the cabinet frame 1 is provided with a grid-connected side isolating switch 8, a grid-connected side main switch 9 and a plurality of electric control indicator light buttons 10, and the rear end of the cabinet frame 1 is provided with the metering transformer 11 and the photovoltaic sub-switch 12; the metering room 2, the circuit breaker room 3, the incoming and outgoing cable room 4, the circuit breaker 5, the relay protection device 6 and the current transformer 7 are all arranged on the cabinet frame 1; the relay protection device 6 includes a relay 13, a current measurement circuit and a voltage measurement circuit, and the circuit breaker 5, the current measurement circuit and the voltage measurement circuit are all electrically connected to the relay 13; the current transformer 7 is electrically connected to the relay 13 through a current signal circuit; the metering transformer 11 is electrically connected to the relay 13 through an output quantity circuit.

[0022] It can be understood that the utility model has a reasonable design and unique structure, and has the following advantages: 1. A low-voltage integrated relay protection with a differential protection function is used to protect the current on both sides of the circuit breaker, the mains power and the energy storage, which more effectively ensures the safety of the energy storage system; 2. The integrated relay protection is used to protect the voltage and frequency of the system to ensure the consistency of the power supply on both sides, and the grid connection is safer and more reliable; 3. The circuit breaker has a reclosing function. After the system fault is eliminated, automatic reclosing can be achieved, eliminating the need for on-duty personnel to go to the site to manually operate the closing and restore the power supply system.

[0023] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A low voltage grid-connected cabinet with automatic reclosing function for fault removal, characterized in that: It includes a cabinet frame, a metering room, a circuit breaker room, an inlet and outlet cable room, a circuit breaker, a relay protection device and a current transformer. The circuit breaker is installed in the circuit breaker room. The lower end of the circuit breaker is connected to the photovoltaic switch or the energy storage side, and the upper end of the circuit breaker is connected to the grid side bus. The grid side copper bar is installed with a metering transformer. The metering room is provided with a bidirectional meter. The current transformer is arranged at the cable end of the grid and the energy storage side away from the grid-connected circuit breaker. The relay protection device collects the currents at both ends for comparison, and drives the circuit breaker to trip according to the current difference.

2. The low-voltage grid-connected cabinet according to claim 1, characterized in that: The front end of the cabinet frame is provided with a grid-connected isolating switch, a grid-connected main switch and a plurality of electric operation indicator light buttons, and the rear end of the cabinet frame is provided with the metering transformer and the photovoltaic sub-switch.

3. The low-voltage grid-connected cabinet according to claim 1, characterized in that: The metering room, circuit breaker room, incoming and outgoing cable room, circuit breaker, relay protection device and current transformer are all arranged on the cabinet frame.

4. The low-voltage grid-connected cabinet according to claim 1, characterized in that: The relay protection device comprises a relay, a current measuring circuit and a voltage measuring circuit. The circuit breaker, the current measuring circuit and the voltage measuring circuit are all electrically connected to the relay.

5. The low voltage grid-connected cabinet according to claim 4, characterized in that: The current transformer is electrically connected to the relay via a current signal loop.

6. The low-voltage grid-connected cabinet according to claim 4, characterized in that: The metering transformer is electrically connected to the relay via an output quantity loop.

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