With the development of science and technology and the growth of energy demand, there are more and more various monitoring and monitoring systems in coal mines, and the amount of data increases sharply. In order to adapt to this situation, the mine monitoring and communication system has developed from the original analog transmission to digital transmission, and put forward the actual requirements for “three networks in one” (data, video and voice signals are transmitted through one channel), and the comprehensive automation of mines The transmission network came into being.
Mine GEPON (Gigabit Passive Optical Fiber Ethernet) is specially developed for underground coal mines with harsh application environment, low cost, broadband and bandwidth can be dynamically allocated, stable system, easy installation and maintenance, low failure rate, flexible networking, easy expansion, It is suitable for comprehensive transmission of video, data, voice and other information, and can be used as a high-speed backbone transmission platform for the whole mine comprehensive automation system. This paper mainly introduces the application design of mining Gigabit passive optical fiber Ethernet in Pingmei 12 Mine.
System technology selection
At present, there are three main types of comprehensive automatic information transmission technology for mining: industrial Ethernet, GEPON and transmission based on SDH technology. GEPON is the latest practical one in PON technology. It not only integrates the low-cost advantage of passive optical network, but also seamlessly integrates with Ethernet technology, which occupies an absolutely dominant position in data network. It has the following advantages: flexible networking, ring, tree, star can be. Seamless integration with Ethernet technology; using optical passive technology for networking; using intrinsically safe access equipment; with a variety of redundant functions; high bandwidth utilization; low cost, easy maintenance and expansion.
Therefore, Pingmei 12 Mine chose GEPON as the platform for mine information transmission among the above three technologies.
System Architecture Selection
Mine GEPON network architecture mainly has two redundant modes: tree and ring. Tree redundancy is characterized by flexible branches, long transmission distance, and a large number of optical network terminals connected to the optical port. However, its optical cable wiring construction is complicated, and it is difficult to monitor the backup optical fiber fault. Ring redundancy is characterized by simple optical cable wiring construction, easy fault monitoring of backup optical fibers, and short switching time for fault redundancy, but the number of optical network terminals connected to each optical port is generally less than 10. However, when the number of setting points is large, multiple rings can be set. The problem of branching and transmission distance can be solved by rationally setting optical network terminals and designing optical power distribution. Therefore, the comprehensive monitoring network transmission of Pingmei 12 Mine adopts the ring-redundant mine GEPON system.
The GEPON system structure of Pingmei 12 Mine is shown in Figure 1, which is mainly composed of ground optical line terminal (OLT), optical splitter (KL5001A) and optical network terminal (ONT).
According to the actual situation of Pingmei No. 12 Mine, the designed GEPON system adopts a double-ring network structure, with one working and one testing standby. The ground computer room is equipped with an optical line terminal, a redundant controller, a computer, a switch, etc. to complete functions such as line status detection, data exchange, data transmission control, and bandwidth allocation. Lay flame-retardant single-mode optical cables from the main wellhead and the auxiliary wellhead respectively to form an optical fiber ring downhole. A total of 8 access points are set up underground, and each access point is set with a passive optical splitter (KL5001A) to form the backbone transmission fiber channel of the system. Each optical splitter is connected to the corresponding ONT, and various underground monitoring and monitoring data, video images, IP voice, etc. are imported, and sent to the ground monitoring host in a centralized and high-speed manner through the passive backbone network. On No. 2 and No. 8 ONTs, access to mine safety monitoring system, video monitoring system, personnel monitoring system, power monitoring system, etc.
System features and main parameters
●Multi-channel industrial TV signals, safety monitoring system signals, production monitoring system signals, IP modulation communication signals, etc. are simultaneously transmitted in one optical fiber.
●With rich software interfaces (OPC, DDE, OD-BEC, FI’P), it seamlessly integrates various subsystems and realizes the integration of management and control of the whole mine.
●With complete network management function, it can realize the management of real-time communication status of OLT and ONT and the function of fault alarm.
●It can set various parameters and report the status of each ONT and OLT, and realize the automatic and manual protection functions of dual-bus and ring-hair structure redundancy of the network system.
●It has the function of port bandwidth allocation.
●The control of uphole and downhole equipment can be realized on any workstation.
●With powerful graphics configuration function, it can Display the real-time dynamic graphics of each subsystem by group screen and split screen.
●With data query statistics, historical curve display, report printing, level-by-level alarm, data system hierarchical management, alarm failure: record, complete event record and other functions.
●Each OLT provides 4 Gigabit Ethernet optical ports, supports 4 ring networks, each ring network uses 2 core optical fibers, and the number of optical network terminals connected is not less than 10.
The backbone optical network adopts downlink broadcasting and uplink TDM adaptation mode, each ONT dynamically allocates a certain time slot (maximum 100MB/s bandwidth), and can comprehensively transmit multi-channel industrial TV monitoring images, safety monitoring system signals, and production monitoring systems. Signals, IP-modulated communication signals, etc., and ensure the real-time performance and transmission quality (QoS) of information exchange.
●The utilization rate of system bandwidth is high, up to 70%, so it can transmit large-capacity video signals smoothly.
●The system has the function of host and line redundancy, which can monitor the status of the OLT port, the on-off status of the spare optical fiber, and realize automatic or manual redundancy switching, so it is reliable and stable.
●The underground optical network terminal adopts intrinsically safe equipment, which is pluggable, small in size, and easy to install.
●The system has RJ45/RS-485 interface, which can easily access the signals of each subsystem.
●The system has two redundant modes of dual bus and ring, which not only ensures the reliability of the system, but also increases the flexibility of the system networking.
●The system adopts gigabit passive optical fiber branch technology. A single ONT failure does not affect the operation of the entire system. The system has good explosion-proof performance, strong anti-interference ability and stable operation.
Main parameters of the system
● backbone network communication rate: 1Gbps.
●Trunk network transmission distance: not less than 10km.
●Number of network nodes: no less than 40.
●Network node communication rate: 10 ~ 100Mbit/s adjustable.
●System redundancy switching time: less than 100ms.
Introduction of main equipment
Optical Line Terminal (OLT)
Optical Line Terminal (OLT) is the central equipment of GEPON system, it provides 4 Gigabit Ethernet ports to core Ethernet and 4 Gigabit Ethernet fiber ports to ONT equipment, with Layer 2/Layer 3 switching and fiber ports Redundancy function.
Equipment interface: ①LAN port: 1, RJ4510/lOOBase-T; ②Uplink interface: 4 GE interfaces; ③PON interface: 4 Gigabit interfaces.
Mine Optical Network Terminal (ONT)
The Mine Optical Network Terminal (ONT) is the field device side device of the GEPON system, which terminates the Ethernet data transmitted from the optical line terminal through the Gigabit passive optical fiber network. In cooperation with the OLT, the ONT can provide comprehensive broadband communication to the connected digital industrial TV system for mining, broadband monitoring for mining, and IP dispatching communication system for mining. The main parameters are as follows:
●Intrinsically safe power supply: DC voltage 15~19V, current not more than 700mA.
●Electrical port: 10/100Base-T adaptive port, intrinsically safe RS-485 port
●Fiber port: The connection port type is sc, single fiber, the upstream working wavelength is 1310nm, the downstream is 1490nlTl, the transmission rate is 1Gbps, and the upstream and downstream allowable optical line attenuation is 28dB.
The redundant controller can realize the port equipment redundancy and line redundancy of the OLT, and can monitor the status of the main equipment OLT working port and the standby equipment OLT port in real time, monitor the on-off status of the standby optical fiber, and realize automatic or manual redundancy switching, etc. .
● Monitor the status of OLT optical ports and ring network fibers in real time.
●When the OLT equipment port fails or the optical fiber is interrupted, it can be switched automatically or manually.
●Double-tree structure can be automatically formed when both the double-ring fibers are interrupted.
●The controller can keep the original state when the power is cut off, and the network communication is not interrupted.
●The switching time of the controller is less than 10ms (the network self-healing time is related to the system).
●Detector detection sensitivity is less than -30dBm.
● Alarm when the OLT optical port is abnormal and the hardware is faulty.
●The controller has automatic and manual control modes.
The construction of the GRPON system in Pingmei 12 Mine provides a high-speed, safe and stable platform for the construction and access of other subsystems in the mine, and has accumulated rich experience for other mines of Pingmei Group. The implementation of this system effectively combines the original separate subsystems of Pingmei 12 Mine, achieves the effects of centralized management, data sharing, and system linkage, and improves the production efficiency of the mine. The video images and monitoring data are uploaded in a centralized manner, which is convenient for maintenance and management, disperses the fault points of the original systems, and makes the system more reliable. The unique redundancy mode of GEPON system makes any fault point on the optical fiber loop not affect the system. Intrinsically safe access equipment enables the optical network terminal to be placed in high gas areas or in coal mining face, tunnel face, etc.
The GEPON system used in Pingmei No. 12 Mine runs stably, with smooth data and image transmission, safe and reliable loops, and power failure or failure of local equipment does not affect the data transmission of the system backbone network.