Dual-power-supply switching system of air-cooled control cabinet of transformer

Abstract

According to the dual-power switching system of the air-cooled control cabinet of the transformer, if abnormal tripping of a contactor occurs during operation, a small bus of a power supply in the cabinet loses voltage, and a voltage monitoring relay cannot find the problem. The output of an I-path incoming line power supply contactor is connected to an I-section power supply miniature bus (10); the output of the II-path incoming line power supply contactor is connected to a II-section power supply small bus (11), and the I-section power supply small bus is connected with the II-section power supply small bus through a power supply small bus interconnection switch (5). The dual-power-supply switching device is used for dual-power-supply switching of the air-cooled control

Description

Technical Field

[0001] The utility model relates to a dual - power switching system for the air - cooled control cabinet of a transformer. Background Art

[0002] At present, in order to ensure the heat dissipation capacity of large main transformers and high - voltage auxiliary transformers in power plants, cooling fans are installed for ventilation and heat dissipation. At the same time, to ensure the reliable operation of the heat dissipation system, the power supply small busbars in the air - cooled control cabinets for on - site cooling fans are all set as dual - power switching circuits for power supply, as Figure 1 shown. However, as the operation time of on - site equipment increases, it is found that there are many problems with the traditional dual - power switching circuit. Problems such as mechanical jamming and electrical short - circuit of the dual - power switching device occur during on - site operation, causing faults in the transformer cooling system, and ultimately leading to transformer tripping. In severe cases, the fault range even expands to the auxiliary PC (MCC) busbar, causing the loss of power of the auxiliary PC (MCC) busbar. In addition, for the dual - power switching circuit of the transformer air - cooled control cabinet in a certain power plant, the two - way power supplies are respectively taken from the turbine PC A and B sections. The two - way power supplies control the main - circuit contactor in parallel through the overload - trip contacts of the circuit breaker and the voltage - monitoring relay contacts in the air - cooled control cabinet to achieve the dual - power switching function. The voltage of the voltage - monitoring relay is taken from the power - supply side of the main - circuit contactor. During operation, if the contactor trips abnormally, the power - supply small busbar in the cabinet will lose voltage, and the voltage - monitoring relay cannot detect this problem. The above situations all seriously threaten the safety of equipment and the reliability of unit operation. Summary of the Utility Model

[0003] The utility model provides a dual - power switching system for the air - cooled control cabinet of a transformer to solve the problems of inability to monitor the voltage of the power - supply small busbar in the air - cooled control cabinet of the transformer, the direct parallel connection of the N - lines of the two circuits, and the difficulty in maintenance and the easy expansion of the fault range when all loads are connected by one section of the power - supply small busbar in case of a fault.

[0004] To achieve the above object, the utility model is realized through the following technical solutions:

[0005] A dual - power switching system for the air - cooled control cabinet of a transformer, which comprises a circuit - I incoming - line power breaker, a circuit - II incoming - line power breaker, a circuit - I incoming - line power contactor, and a circuit - II incoming - line power contactor. The incoming - line end of the I - power is connected to the circuit - I incoming - line power breaker. The output of the circuit - I incoming - line power breaker is connected to the circuit - I incoming - line power contactor. The output of the circuit - I incoming - line power contactor is connected to the I - section power - supply small busbar;

[0006] The incoming line terminal of the II power supply is connected to the II incoming line power circuit breaker. The output of the II incoming line power circuit breaker is connected to the II incoming line power contactor. The output of the II incoming line power contactor is connected to the II-section power sub-busbar.

[0007] The I-section power sub-busbar and the II-section power sub-busbar are connected through a power sub-busbar tie switch.

[0008] For the dual-power switching system of the transformer air-cooling control cabinet, the I-section power sub-busbar is connected to a power sub-busbar voltage monitoring relay.

[0009] For the dual-power switching system of the transformer air-cooling control cabinet, the power sub-busbar voltage monitoring relay is electrically connected to a voltage display panel. Beneficial effects

[0010] 1. The utility model is equipped with a power sub-busbar voltage monitoring relay and is connected to a voltage display panel at the same time, which can real-time monitor the voltage of the power sub-busbar in the transformer air-cooling control cabinet, making it convenient for inspection personnel to understand the operation status of the equipment, promptly discover abnormalities and make corresponding treatments, and avoid the expansion of the fault range caused by the loss of voltage of the air-cooling control cabinet.

[0011] 2. The utility model transforms the original busbar of the transformer air-cooling control cabinet from one power sub-busbar into two power sub-busbars. After the transformation, it can prevent the situation where all incoming line power supplies and loads have to be cut off when a fault occurs in one power sub-busbar, improving the reliability of power supply.

[0012] 3. For the transformer cooling fan and oil submerged pump of the utility model, they are switched between the two busbars through a load switching switch. The load switch not only facilitates the isolation of load faults but also the switching to the normal busbar when a single busbar fails, improving the operation reliability of the air-cooling control system.

[0013] 4. The incoming line power circuit breaker of the utility model is replaced from a 3P circuit breaker to a 3P+N circuit breaker, and the original connection method of directly connecting the N lines of the two power supplies is changed to the method of connecting the N lines after passing through the circuit breaker, which can effectively prevent the influence on both power supplies when a fault occurs in the N line and ensure the reliability of the control circuit. Description of the drawings

[0014] Figure 1 is the circuit diagram of the original dual-power switching system;

[0015] Figure 2 is the circuit diagram of the dual-power switching system of the utility model;

[0016] In the figure: 1. Circuit I incoming power breaker; 2. Circuit II incoming power breaker; 3. Circuit I incoming power contactor; 4. Circuit II incoming power contactor; 5. Power small bus tie switch; 6. Power small bus voltage monitoring relay; 7. Voltage display panel; 8. Contactor mechanical interlock device; 9. Monitoring background; 10. Section I power small bus; 11. Section II power small bus. Specific implementation mode

[0017] Refer to Figure 2 , a dual-power switching system for a transformer air-cooled control cabinet, which comprises a Circuit I incoming power breaker 1, a Circuit II incoming power breaker 2, a Circuit I incoming power contactor 3 and a Circuit II incoming power contactor 4. The incoming end of Circuit I power is connected to the Circuit I incoming power breaker, the output of the Circuit I incoming power breaker is connected to the Circuit I incoming power contactor, and the output of the Circuit I incoming power contactor is connected to Section I power small bus 10;

[0018] The incoming end of Circuit II power is connected to the Circuit II incoming power breaker, the output of the Circuit II incoming power breaker is connected to the Circuit II incoming power contactor, and the output of the Circuit II incoming power contactor is connected to Section II power small bus 11;

[0019] The Section I power small bus and the Section II power small bus are connected through a power small bus tie switch 5.

[0020] For the dual-power switching system of the transformer air-cooled control cabinet, the Section I power small bus is connected to a power small bus voltage monitoring relay 6, the power small bus voltage monitoring relay is electrically connected to a voltage display panel 7, and at the same time, the power small bus voltage monitoring relay is also wirelessly connected to a monitoring background 9, and can transmit signals to the background monitoring system to realize remote monitoring;

[0021] The power small bus voltage monitoring device used in the present invention, after collecting the voltage, on the one hand, connects to a voltage display screen through a communication cable to display the power small bus voltage value in real time, and on the other hand, converts the collected voltage signal into a 4-20 mA signal and transmits it to the background monitoring system to realize remote monitoring;

[0022] The power small bus of the present invention uses a sectional power small bus, and the loads are evenly distributed and connected to different sectional small buses, which is convenient for isolation in case of on-site load faults, and can ensure that there are always cooling fans and oil pumps running in the cooling system during maintenance work, improving the operation reliability of the transformer.

[0023] To effectively prevent the occurrence of unsafe events such as the expansion of the fault range caused by the adhesion of the main power contactor contacts and other faults, a double interlock method of a mechanical interlock device plus an electrical interlock is used between the two main power contactors. The interlock form, structure, and working principle of the mechanical interlock device adopt the forms of existing technologies. This device only applies the mechanical interlock device here to achieve the effect of mechanical interlock;

[0024] The incoming line power circuit breaker used is a 3P+N circuit breaker, and the circuit breaker has a built-in N-line protection function. When a fault occurs on the N-line, the circuit breaker can trip to cut off the fault, preventing the N-line fault from affecting the upper-level power distribution device of the two incoming line power supplies.

Claims

1. A dual power switching system for a transformer air-cooled control cabinet, characterized by: The circuit breaker comprises an I-way incoming power circuit breaker, an II-way incoming power circuit breaker, an I-way incoming power contactor and an II-way incoming power contactor. The incoming end of the I power supply is connected to the I-way incoming power circuit breaker, the output of the I-way incoming power circuit breaker is connected to the I-way incoming power contactor, and the output of the I-way incoming power contactor is connected to the I-section power busbar. The incoming line end of the II power supply is connected to the II incoming line power circuit breaker, the output of the II incoming line power circuit breaker is connected to the II incoming line power contactor, and the output of the II incoming line power contactor is connected to the II section power busbar; The section I power busbar and the section II power busbar are connected via a power busbar contact switch.

2. The dual power switching system for transformer air-cooled control cabinet according to claim 1 is characterized in that: The I-section power bus is connected to the power bus voltage monitoring relay.

3. The dual power switching system for transformer air-cooled control cabinet according to claim 2 is characterized in that: The power supply small bus voltage monitoring relay is electrically connected to the voltage display panel.

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