Rail transit switch cabinet frame protection device

Abstract

The utility model relates to the technical field of traction power transformation, and discloses a rail transit switch cabinet frame protection device which comprises a switch cabinet frame, a current protection element, a programmable controller and a circuit breaker, the current protection element is electrically connected with the programmable controller and the circuit breaker respectively, one end of the current protection element is connected with the switch cabinet frame, and the other end of the current protection element is connected with the circuit breaker. The other end of the current protection element is grounded. According to the utility model, the problem that short-circuit accidents are easy to occur in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to traction power transformation technical field, concretely is a kind of rail transit switch cabinet frame protection device. BACKGROUND

[0002] Rail transit high-voltage electric disconnector cabinet (including visual grounding system) in traction substation is installed with insulation.When leakage occurs between 1500V positive electrode in switch cabinet and equipment shell, if not removed in time, it is easy to expand the fault to short-circuit accident between 1500V positive electrode and negative electrode through equipment shell.

[0003] And the short-circuit current of direct current system is very big, the short-circuit current when positive electrode and negative electrode short-circuit can reach tens of thousands of amperes, which will cause serious harm to direct current equipment. CONTENT OF UTILITY MODEL

[0004] In order to overcome the deficiencies of the prior art, the utility model provides a kind of rail transit switch cabinet frame protection device, solve the problems, such as easy to occur short-circuit accident of prior art.

[0005] The technical scheme adopted by the utility model to solve the above problems is:

[0006] A kind of rail transit switch cabinet frame protection device, including switch cabinet frame, current protection element, programmable controller, circuit breaker, current protection element is electrically connected with programmable controller, circuit breaker respectively, one end of current protection element is connected with switch cabinet frame, the other end of current protection element is grounded.

[0007] As a preferred technical scheme, current protection element is electrically connected with overcurrent relay FP and outlet relay KA.

[0008] As a preferred technical scheme, current protection element includes current relay FP, shunt RL, current transmitter FT, outlet relay KA, protection unit that are electrically connected in sequence, current relay is connected with switch cabinet frame, shunt is grounded.

[0009] As a preferred technical scheme, wherein, protection unit includes power module, CPU module, memory, analog input module, digital quantity input port and output port, external interface, CPU is connected with analog input module, memory and external interface respectively.

[0010] As a preferred technical scheme, external interface includes external primary interface and secondary interface, external primary interface includes the protection ground of the current protection element one end, the rail backflow steel rail of the voltage protection element one end, external secondary interface includes the wiring port of the trigger upper circuit breaker trip of protection unit digital quantity output port.

[0011] As a preferred technical scheme, the action nodes of the current relay include a common node, a normally closed node and a normally open node.

[0012] As a preferred technical scheme, the short-circuit current capacity of the current protection element is greater than or equal to 50kA 200ms.

[0013] As a preferred technical scheme, the voltage protection element is included, and the voltage protection element, the programmable controller and the circuit breaker are electrically connected respectively, one end of the voltage protection element is connected with the switch cabinet frame, and the other end of the voltage protection element is connected with the track return rail.

[0014] As a preferred technical scheme, the voltage protection element is electrically connected with a potential relay.

[0015] As a preferred technical scheme, the voltage protection element is electrically connected with a voltage transmitter.

[0016] Compared with the prior art, the utility model has the following beneficial effects:

[0017] (1) the utility model discloses can effectively prevent the leakage or insulation damage flashover of the direct current switch live equipment to the direct current cabinet body, and when the rest direct current protection does not play the due role, the harm to the person and equipment is produced to the person and equipment;

[0018] (2) the frame leakage protection in the utility model discloses is the protection measure when the positive pole and the cabinet body occur the fault to the high-voltage electric disconnecting circuit breaker cabinet, when the positive pole occurs insulation damage to the cabinet body shell, can timely remove the fault, guarantees the safe operation of system. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 It is frame protection device working principle schematic diagram;

[0020] Fig. 2 It is current protection element working principle schematic diagram;

[0021] Fig. 3 It is overcurrent protection time limit characteristic schematic diagram. DETAILED DESCRIPTION

[0022] The utility model will be further explained in detail in combination with examples and drawings, but the implementation mode of the utility model is not limited to this.

[0023] Example 1

[0024] As Figs. 1 to 3 shown, 1. overview

[0025] 1.1 frame protection definition

[0026] The setting of DC frame protection is to prevent the leakage or insulation damage flashover of the DC switch live equipment to the DC cabinet body, and when the rest of the DC protection does not work as expected, it will cause harm to the person and equipment.

[0027] The frame leakage protection in this scheme is a protection measure for high-voltage electric disconnector cabinet (including visual grounding system) when the positive pole fails to the cabinet body. The protection principle is to remove the fault in time when the positive pole fails to the cabinet body shell, ensuring the safe operation of the system.

[0028] 1.2 Frame protection classification

[0029] Frame protection is divided into current type frame protection and voltage type frame protection. Voltage type frame protection is the backup protection of current type frame protection.

[0030] 1.2.1 Current type frame protection

[0031] Current type frame protection detects the current between the frame and the ground through a current element. When the detected current value reaches the setting, the current type frame protection will start.

[0032] 1.2.2 Voltage type frame protection

[0033] Voltage type frame protection detects the voltage between the frame and the negative pole through a voltage protection element. When the detected voltage reaches the set value and reaches the set delay, the voltage type frame protection will start, and the station's DC traction system will trip and lock the station's DC circuit breaker reclosing. Frame voltage protection also cooperates with the rail potential limiting device of the station as the backup protection of the rail potential limiting device.

[0034] 1.3 Possible reasons for frame protection action

[0035] 1. Contact net short circuit with frame leakage;

[0036] 2. Contact net flashover or local continuous discharge with frame leakage;

[0037] 3. Frame leakage caused by rodents or other animals and objects;

[0038] 4. High rail potential causing frame voltage action;

[0039] 5. Short circuit or discharge of switch cabinet positive pole or cable to frame;

[0040] 6. Misoperation or left tools during cleaning causing positive pole short circuit to frame.

[0041] 2. Frame protection device working principle

[0042] The low impedance frame leakage protection device of the high-voltage electric isolation switch cabinet (including visual grounding system) for rail transit is a measurement and control integrated device composed of a high-performance PLC processor, a high-precision data acquisition system, and current and voltage elements, and is suitable for the frame protection of the DC traction power supply system of urban rail transit and can meet the traction power supply system with a power supply voltage level of DC 750V or DC 1500V. The current and voltage elements of the frame protection device are all installed in the switch cabinet and have the functions of withstanding short-circuit current, alarming, operating mode, and electric test grounding interlocking, and are used to protect the frame leakage fault in the cabinet, and the voltage and current double protection can trip the upper circuit breaker when the protection acts. The working principle of the frame protection device is shown in Fig. 1 , and the working principle of the current protection element is shown in Fig. 2 .

[0043] The installation position of the frame protection element: the current type protection element is installed in the switch cabinet and connected between the insulated switch cabinet shell and the substation grounding grid. The voltage type frame protection element is also installed in the switch cabinet and connected to the negative pole of the DC power supply and the device shell.

[0044] The high-voltage electric isolation switch cabinet (including visual grounding system) for rail transit is installed in insulation, and the cabinet body is electrically connected and insulated from the ground. The frame protection device is installed in the cabinet and used to prevent personal injury and equipment damage caused by internal insulation damage flashover of the switch cabinet, and to protect special faults. The frame protection current and voltage elements of the device are respectively provided with protection and outlet relays, and have independent action outlets and alarm information. The current element monitors the leakage current between the switch cabinet frame and the negative pole of the traction system, and the adjustable voltage element (potential relay or voltage transmitter) is used for the potential difference between the cabinet body and the negative pole of the traction system. The current and voltage protection of the frame protection are respectively provided with protection outlets and outlet relays, and the current and voltage elements can independently or together send a trip or inter-trip command to the power supply system of the substation. When a device fault is detected, any of the above relays acts, and the upper circuit breaker is tripped and locked, and an alarm signal is sent.

[0045] After the frame protection trips, the lock of the tripped circuit breaker is closed, and only when the fault disappears and the local frame protection is restored, the circuit breaker can be closed, and local, remote or automatic restoration can be selected.

[0046] The frame protection has a whole put-off function. The voltage element can be locally put in / cut off, has an alarm and trip function, and the trip section can be set to a reverse time curve. When a protected device fails, the larger the fault current (or short-circuit current) is, the smaller the action delay of the protection is, that is, the current and the action time are inversely proportional, as shown in Fig. 3 .

[0047] The setting value of the frame protection can be set by the user on site, and the action setting value and time are continuously adjustable. After the action of the frame protection, the action signal of the frame protection can be displayed locally / remotely, and if it continues to run, it has the function of "frame fault alarm not cleared" and local protection device viewing SOE.

[0048] The setting value of the current type and voltage type frame protection is set according to the human tolerance curve, which is:

[0049] Current trip value (A) 35

[0050] Voltage alarm value (V) 95

[0051] Voltage trip U1> (V) 130, voltage trip delay t1> (s) 1.0

[0052] Voltage trip U2> (V) 150, voltage trip delay t2> (s) 0.9

[0053] Voltage trip U3> (V) 240, voltage trip delay t3> (s) 0.6

[0054] Voltage trip U4> (V) 350, voltage trip delay t4> (s) 0.4

[0055] Voltage trip U5> (V) 450, voltage trip delay 5> (s) 0.2

[0056] Voltage trip U6> (V) 490, voltage trip delay 6> (s) 0.16

[0057] Voltage trip U7> (V) 600, voltage trip delay 7> (s) 0.1

[0058] To avoid the stray current causing the frame leakage protection device malfunction, the frame current has a direction judgment function, the forward protection tripping (frame to ground current leakage), the reverse alarm (ground to frame current leakage), the signals can be uploaded to the background equipment, and at the same time, the frame forward current can be judged twice, the first time only jump the corresponding switch of the station, and then after t delay, the second time is judged, if the frame fault still exists, jump the adjacent station. The t delay range of the second judgment is 0-500 ms adjustable.

[0059] 3. Main functions of the device

[0060] 3.1 Protection function

[0061] Frame overvoltage protection

[0062] Frame overcurrent protection

[0063] 3.2 Auxiliary function

[0064] Action record (store action report)

[0065] Alarm record (store alarm report)

[0066] Operation record (store operation record)

[0067] SOE event record (store remote signal change report)

[0068] Maintenance event record (store the number of times and total times of various protection actions)

[0069] Protection event record (store protection event record)

[0070] Fault recording (store the latest 16 times of fault recording data, including track current, track voltage, and various relay word states, recording time length 2000ms, trigger time can be set), recording file format conforms to the standard of "GB / T 22386-2008 General Format for Transient Data Exchange in Power Systems" (IEC 60255-24:2001, JDT).

[0071] Has independent protection setting value for different operation modes. Stored in EEPROM, no loss in power failure.

[0072] Adopt large screen LCD display, good man-machine dialogue interface, easy to use and operate.

[0073] 3.3 Measurement and control function

[0074] Current and voltage measurement: frame voltage Utv1, frame voltage Utv1, frame leakage current If1, etc.

[0075] Remote signaling: remote signaling is realized through TCP Modbus communication protocol.

[0076] Remote control: mapping of software virtual to hardware output is realized through programmable logic.

[0077] 3.4 Self-checking function

[0078] The device can automatically detect hardware failure and make corresponding alarm report and light up the alarm light.

[0079] 4. Optimization scheme of current protection element

[0080] The current protection element usually adopts a shunt plus current transducer scheme, in which the shunt converts the frame leakage current from the equipment cabinet to the system ground into a primary millivolt level voltage signal input into the current transducer, and the current transducer converts the primary millivolt level voltage signal into a secondary milliamper level analog quantity input into the protection unit. However, the primary millivolt level voltage signal converted by the shunt is susceptible to strong electric interference, and the secondary milliamper level analog quantity is susceptible to external factors such as secondary wiring process, virtual connection after periodic element test recovery, unreliable shielding layer ground, and transducer power supply fluctuation, thereby causing the risk and hidden danger of misoperation.

[0081] The design optimization goal of the frame leakage current protection device current element scheme adopted in the project is to reduce or eliminate the misoperation possibility of frame leakage current protection, enhance the reliability of the DC traction power supply system, and reduce the risk of abnormal operation of the DC traction power supply system. As follows:

[0082] The current element is composed of a shunt, a current transducer, a current relay, and a protection unit, as shown in the above "current protection element working principle diagram". The protection unit includes a power supply module, a CPU module, a memory, an analog quantity input module, a digital quantity input port and an output port, and an external interface (the external interface includes an external primary interface and a secondary interface). The CPU is connected with the analog quantity input module, the memory, and the external interface respectively. The action nodes of the current relay include a common point, a normally closed point, and a normally open point, which are connected with the switch cabinet frame through primary cables or copper bars. The current relay and the shunt are connected in series through a primary copper bar and are connected to the substation system ground. The action signal of the current relay is connected with the digital quantity input port of the protection unit in the form of a hard connection point. The input end of the current transducer is connected with the shunt, and the output end is connected with the analog quantity input module of the protection unit through an analog quantity special cable.

[0083] The system adds a primary element current relay that directly acts according to the frame leakage current. Only when the "current relay" acts and the "shunt plus current transducer" monitors the positive action current, the frame leakage current protection device outputs the protection action tripping signal of "tripping the local traction power supply equipment and tripping the adjacent power supply equipment", thereby reducing the misoperation possibility of frame leakage current protection, enhancing the reliability of the DC traction power supply system, and reducing the risk of abnormal operation of the DC traction power supply system. Since the action node of the current relay is the linkage node of its own mechanical structure, and the action signal is input into the protection unit in the form of a hard connection point, the current relay has the advantages of not being affected by external strong electric interference signals and accurate and reliable action.

[0084] 5. Performance requirements of the frame protection device

[0085] 5.1 The requirement that the current element withstands a short-circuit current of not less than 50 kA for 200 ms

[0086] 5.2 Voltage element - potential relay or voltage transmitter has the advantages of wide control range, small error, high repeatability and linearity, low noise, high reliability and long service life.

[0087] 5.3 Device metal shell

[0088] The switch cabinet frame leakage current protection device is externally provided with a metal shell, the external metal shell effectively protects the analog signal collected by the device from external electromagnetic interference, ensures the accuracy of the measurement circuit, and simultaneously adopts integrated and modular design, the external interface is simple and clear, and installation wiring in the switch cabinet is facilitated. Through the integrated structure design, the field construction and installation difficulty and wiring difficulty are reduced.

[0089] Meanwhile, all the switch cabinet bodies are externally provided with metal blocking bottom plates with cable entrances and exits, the entire DC switch cabinet body has high protection level and good isolation effect. The cable entrance and exit cabinet body is provided with fixing and protection devices, meets the cable installation requirements and prevents mechanical damage.

[0090] 5.4 Switch cabinet bottom insulation installation

[0091] The frame leakage protection device can avoid the damage of the cabinet insulation, the flow of the ground stray current through the current element and the misoperation of the frame leakage protection device, and can distinguish the normal switch cabinet crash fault. The scheme is as follows: the switch cabinet bottom of the insulation installation is provided with a high-performance polycarbonate insulation pad and a polytetrafluoroethylene gasket used during installation and positioning, which ensures good insulation performance and ensures reliable operation of the current element. Polycarbonate and polytetrafluoroethylene have outstanding impact toughness and anti-creep performance, have high heat and cold resistance, low water absorption, small shrinkage, stable size, good wear resistance, certain corrosion resistance, excellent insulation performance, and are not affected by environmental humidity, which can ensure the insulation installation effect of the entire switch cabinet.

[0092] 5.5 Wiring between device element components

[0093] The wiring between the potential relay or voltage transmitter, the current relay, the shunt and the measuring device all adopts shielded twisted pair wire, and has strong anti-interference ability.

[0094] As described above, the utility model can be better realized.

[0095] All the features disclosed by all the examples in the specification, or all the steps of the methods or processes disclosed by the specification, can be combined and / or extended in any manner, except for mutually exclusive features and / or steps, and / or replaced by alternative features and / or steps.

[0096] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form. Any simple modification, equivalent replacement, improvement, etc. made to the above embodiments, in accordance with the technical essence of the present application, and within the spirit and principles of the present application, shall still fall within the protection scope of the technical scheme of the present application.

Claims

1. A rail transit switchgear frame protection device, characterized in that, The switch cabinet frame, the current protection element, the programmable controller, and the circuit breaker are electrically connected respectively, one end of the current protection element is connected with the switch cabinet frame, and the other end of the current protection element is grounded; the current protection element is electrically connected with an overcurrent relay FP and an outlet relay KA; the current protection element comprises a current relay FP, a shunt RL, a current transmitter FT, an outlet relay KA, and a protection unit which are electrically connected in sequence, and the current relay is connected with the switch cabinet frame, and the shunt is grounded.

2. The rail transit switch cabinet frame protection device according to claim 1, characterized in that, The protection unit comprises a power supply module, a CPU module, a memory, an analog input module, a digital input port and an output port, and an external interface, and the CPU is connected with the analog input module, the memory, and the external interface respectively. The external interface comprises a primary interface and a secondary interface, the primary interface comprises a protection ground connected with one end of the current protection element and a rail return track connected with one end of the voltage protection element, and the secondary interface comprises a wiring port connected with the digital output port of the protection unit and triggering the trip of the upper circuit breaker.

3. The rail transit switch cabinet frame protection device according to claim 2, characterized in that, The action nodes of the current relay comprise a common point, a normally closed point, and a normally open point.

4. The rail transit switch cabinet frame protection device according to claim 3, characterized in that, The current protection element can withstand a short-circuit current of greater than or equal to 50 kA for 200 ms.

5. The rail transit switch cabinet frame protection device according to claim 1, characterized in that, The switch cabinet frame, the voltage protection element, the programmable controller, and the circuit breaker are electrically connected respectively, one end of the voltage protection element is connected with the switch cabinet frame, and the other end of the voltage protection element is connected with the rail return track.

6. A rail transit switchgear frame protection device according to any one of claims 1 to 5, characterized in that, The voltage protection element is electrically connected with a potential relay.

7. The rail transit switchgear frame protection device according to claim 6, characterized in that, The voltage protection element is electrically connected with a voltage transmitter.

8. The rail transit switch cabinet frame protection device according to claim 6, characterized in that, ​

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