A paper on the remote control technology of high-speed railway contact network isolation switch
1 Current status of remote control of contact network isolation switch
At present The remote control of high-speed railway contact network isolation switch is mainly in the form of optical fiber control. The optical fiber control form is mainly developed based on the concept of digital substation. Its main features are: (1) Reduces the number of indoor and outdoor control cables passing through, thereby reducing External causes such as lightning and electromagnetic hazards to the equipment inside; (2) Control signals are transmitted using optical cables, which reduces interference. This control form also brings new problems, mainly reflected in:
① Electronic components such as RTU are placed in the outdoor control box, the operating environment is poor, and the component damage rate increases.
②Control loops and logical judgments have become complex, and links have increased, leading to an increase in uncertain factors such as signal misdisplay.
③The working power supply of RTU, operating mechanism control board and other operating power supplies are in the same path. When the power supply voltage is unstable, instability factors in each link will increase.
According to incomplete statistics, since the opening of the high-speed rail, the train has malfunctioned more than 10 times, refused to operate more than 30 times, and the switch position has been incorrectly displayed more than 100 times. Although it has undergone many special rectifications, the symptoms have not been cured. If the root cause is not addressed, problems and hidden dangers will still exist, without fundamentally solving the problem.
2 Cause Analysis
2. 1 Reasons for the malfunction of the catenary isolation switch. The reasons for the malfunction of the catenary isolation switch are as follows.
(1) The signal connection between the RTU and the operating mechanism is interfered, which mistakenly triggers the self-holding circuit of the operating mechanism, causing the switch to malfunction. The operation found that the interference signal does exist, especially when the catenary fails, the interference signal is the strongest. For example: After the catenary isolation switch malfunctioned on the Hainan East Ring Line, the catenary work area and relevant personnel conducted measurements on site. After the external 220 V power supply was turned off, a voltage of 40 to 90 V was still measured at the connecting line.
It is worth noting that there is another hidden danger in the connection between the isolating switch operating mechanism and the RTU. If the 220 V power supply fire and ground wires are connected reversely, the RTU outlet relay may break the neutral line, which is a greater risk. . In bad weather, if the insulation of the connection is reduced or is instantaneously grounded, it will directly lead to erroneous operation commands.
During operation, the heating circuit in the operating mechanism box of the contact line isolating switch often reports abnormal operation; in Dezhou, Xuzhou, Zhengzhou and other places of the Beijing-Shanghai high-speed railway, when the contact line fails, the isolating switch operating mechanism box The internal air switch has tripped. This confirms from another side that there is indeed an induced voltage (current), but it just interferes with different circuits.
(2) The outlet control relay of the operating mechanism is faulty. When the dispatch console issues a command, the operation cannot be performed, but the operating command is retained inside the operating mechanism. In subsequent operations, the outlet relay may recover and the operating command will then act causing the switch to operate.
(3) The IP address of the RTU conflicts, causing another switch to malfunction when operating the switch. This phenomenon often occurs after a new RTU is replaced due to careless replacement personnel.
(4) The operation button and PLC of the contact network isolation switch control panel mistakenly issued commands. This type of failure occurred in the Wuhan-Guangzhou section of the Beijing-Guangzhou high-speed railway. It has occurred three times and has been resolved after delayed processing.
2. 2 Reasons why the contact network isolation switch refuses to operate (1) The air switch in the isolation switch operating mechanism box tripped.
The tripping of any of the four switches A1, A2, B1, and B2 will cause the contact network isolation switch to refuse to operate. The B1 switch has the most trips during operation, and this phenomenon mostly occurs during catenary failure periods.
(2) Electronic components are damaged.
(3) The transmission channel is interrupted.
2. 3 Reasons for the incorrect display of the position signal of the contact network isolating switch
(1) During operation, it was found that the integrated switchboard of the traction substation is prone to mistakenly transmitting remote signals when switching between the main and backup channels. signal, causing the dispatch console to display incorrectly.
(2) The RTU or operating mechanism circuit board is interfered with and displays incorrectly.
(3) The control circuit components are damaged.
Incorrect display will cause the dispatcher to be at a loss. For example: During the operation of the Zhengxi High-speed Railway, the isolation switch of the contact network separation phase showed that it is closed. The dispatcher immediately started the opening operation, but it showed that the operation timed out and could not open the gate. 6 minutes later, the switch automatically opened again. I still don’t know whether the switch actually acted or displayed by mistake.
3 Solutions
The basic guiding ideology to solve the problem of misoperation, refusal to operate and misdisplay of the contact line isolating switch is to eliminate interference and strengthen control even if interference exists. Will not move accidentally. There is currently no good way to eliminate interference except standard construction and careful grounding. Therefore, the main focus should be on strengthening control.
3. 1 Preventing the misoperation of the contact line isolating switch
Under the existing control method of the high-speed railway contact line isolating switch, there are three main measures to prevent misoperation: First, learn from The advantages of the direct cable control method are that the operating power supply is disconnected when not operating to achieve dual control of the motor control loop; the second is the dual-port output of control commands; the third is the delayed release of the self-holding function of the operating motor loop.
The operating mechanism box controls the motor circuit air switch B1 to add a remote operating mechanism and realize dispatched remote operation. This switch is turned off when not in operation. Cancel the A2 and B2 switches.
The switch is connected in series with the control command outlet contactor, which plays a dual control role in the motor circuit, greatly reducing the probability of malfunction caused by interference signals.
Change the RTU outlet relay to a dual node, and disconnect the fire and ground wires of the 220 V control command at the same time. The dual-port output reduces the probability of malfunction caused by interference compared with the single-port output.
Release the self-holding function of the self-holding relay in the operating mechanism box regularly to avoid being immobile during operation and malfunctioning when not operating.
3. 2 Measures to prevent the contact network isolating switch from refusing to operate
Adding remote operation of the operating mechanism to the B1 switch not only eliminates misoperation, but also achieves the effect of killing two birds with one stone by canceling A2 and B2 Switch, B1 switch is in the open state normally and will no longer cause tripping. All low-pressure air switches should be equipped with auxiliary contacts and position signal transmission consoles.
3. 3 Measures to prevent false display of switch position
(1) The contact network isolation switch monitoring screen is directly connected to the SCADA and no longer passes through the integrated switch.
(2) RTU and operating mechanism control module self-check and alarm. When the module cannot work normally, it will alarm the dispatch station. At this time, all switch action remote signaling information will be ignored.
(3) When the B1 switch is in the open state, the operating power supply is not turned on. The action signal of the contact network isolation switch that appears during this process can generally be judged as a false message and ignored. At the same time, the method for dispatchers to determine whether the contact line isolating switch is mis-operated or mis-displayed is enhanced.
4 Conclusions
(1) Analyze the causes of malfunction, refusal to operate and no display of the contact network isolation switch under optical fiber control mode, and propose improvement measures for designers to learn from .
(2) The problems existing in the remote control of the contact network isolating switch also show that the two forms of optical fiber control and cable direct control have their own advantages and disadvantages, and they should learn from each other, learn from each other's strengths and complement each other's weaknesses, and gradually improve them. The remote control of the contact network isolation switch requires system design and cannot completely rely on simple overlap of products from different manufacturers. ;