With the continuous improvement of coal mine modernization, the requirements for the stability, safety and uninterruptedness of underground power supply and distribution system in coal mine are becoming higher and higher. Most of the high and low voltage integrated protectors used in underground power supply have RS-485 communication interface, but the specifications are various, the product time span is long, and the communication protocols are various, which brings difficulties to the construction of underground power supply monitoring system. In this paper, a high-speed intelligent programmable serial port controller is used to build a power supply monitoring system for underground coal mines. The system has been tested for a long time in Qunan coal mine of the mining and mining group company and has reliable operation. Coal mine production in the underground operation, power supply load site environment, geological conditions are complex. With the continuous improvement of coal mine modernization in recent years, the increase of underground power supply distance and the increasing demand for power supply and distribution, the stability, safety and uninterrupted requirements of underground power supply and distribution system in coal mine are also higher and higher. Nowadays, in the industrial field control network, serial communication network is the most widely used and the lowest cost communication mode, among which RS458 is the most commonly used.
With the increasing amount of communication data, serial communication also brings the problem of high delay and low speed. At the same time, in the process of constructing the power supply monitoring system of coal mine, many manufacturers are faced with the problem of integrating different types of integrated protectors into the system. Because different manufacturers and even the same manufacturer have different communication protocols for different models and different periods, the system will bring great difficulties to the system construction.
In this paper, the Programmable Serial Controller (PSC) technology is used to construct the power supply monitoring system for underground coal mines, which solves the above problems and ensures the safety of power supply in underground coal mines. The polling system is used in the underground serial communication of coal mine, that is, when the communication rate of bus is constant, the refresh time of system data is equal to the communication time of a single extension * the number of extension bus usage rate. Improve bus usage. Add an appropriate device between the computer and the extension.
When the computer does not communicate with the following extension, the device continues to communicate with the extension, and stores the data in its own cache.
As long as the computer needs the data, it immediately distributes the data to the computer wholesale through ethernet. PSC is based on the above principles, using multi CPU parallel communication processing and ultra large capacity caching technology, and parallel communication of a number of intelligent controllers or meters. The data obtained are stored in ultra large capacity cache, and then sent to the upper monitoring equipment in batches. The former serial communication mode is changed to multi-channel parallel processing method.
All controlled devices are grouped and batched according to their addresses, and batch communication is carried out with built-in super-large capacity cache.
The disadvantages of low communication rate, delayed communication time and incompatibility of various communication protocols in the large-scale serial control network are overcome. The architecture of PSC is based on ARM processor. The ARM processor uses 32-bit embedded ARM Cortex SCM STM32F103x as the CPU of PSC. Each processor has two serial ports that can be processed in parallel.
There are four processors, which can process eight serial ports in parallel. The device can be grouped and batched according to address, and communicated in batches with large capacity cache. The processing speed is fast and compatible with the field.
The same kind of communication protocol. PSC has the characteristics of program storage and independent operation. The communication protocol of comprehensive insurance is converted and stored on PSC. Even if the comprehensive insurance is replaced, there is no need to rewrite the program, so that it can be used immediately. PSC can operate independently, even if the upper computer is missing, it can also ensure the normal monitoring of equipment. In the power supply monitoring system of coal mine, it is difficult to confirm whether the on-site comprehensive insurance output signal is intrinsically safe through the correlation test. According to the GB3836 regulation, the non intrinsic RS-485 signal is connected with the intrinsically safe equipment to do signal isolation processing, that is to add a RS-485 signal isolator between the non intrinsic safety signal and the intrinsically safe device. In this paper, ADM2483 is selected as the isolation chip matched with PSC.
The magnetic coupling isolation channel and RS-485 transceiver are integrated in the chip. The design circuit is simple and convenient. RS-485 signal isolation can be realized by a single chip. The product is small in size, power consumption is only 1/10 of the traditional optocoupler isolation, transmission delay is ns level, and reliability is high, which enhances the security and anti-interference of signal transmission. PSC has programmable function using PC programming language, and has strong expansibility and integration.
Using programming tools, different communication protocols can be converted into standard protocols, so as to achieve the function of supporting communication between different integrated protection devices without changing the comprehensive insurance. The software of programming development platform matched with PSC is Rstep. The software is programmed by ladder diagram. The ladder diagram is very similar to the circuit diagram of the electrical control system. It has the advantages of intuition and understandability, and is easy to be mastered by factory electrical personnel. This paper uses the PSC technology to build the underground power supply monitoring system of coal mine with three layers of network structure, such as management layer, information layer and equipment layer, as shown in Figure 2. Management: The main ground control station and the dispatch management center constitute the management layer. Industrial Ethernet communication is adopted, which is based on the EtherNet/IP network structure of IEEE802.3 standard. The equipment group is connected to the industrial network switch point to point, and the switch provides RJ-45 or SC ports. The transmission rate is 1000/100Mbps, and the transmission medium is single mode optical fiber or five kinds of twisted pair shielded wire.
Information layer: underground ring network and ground network constitute information layer. The information layer is an EtherNet/IP network structure based on IEEE802.
3 standard. The communication between monitoring substation and underground ring network switch is based on ethernet. The monitoring substation and monitoring substation are connected by underground ring network, and the underground ring network is connected by optical fiber and ground network. Equipment Layer: The device layer consists of integrated protector, transmission bus and monitoring substation. The integrated protector is connected to the Monitoring Sub-station through bus, thermostatic element and the PSC in the Monitoring Sub-station transforms different protocols and stores them. The monitoring substation is connected with the underground switch through ethernet. Rapidity: Monitoring sub-station and comprehensive insurance process data through PSC.
Each PSC has two serial ports that can be processed in parallel.
It can process eight serial ports in parallel. It can group and batch comprehensive insurance according to address, which improves the real-time performance of the system. The system runs reliably and fast, and the response time is less than 1 s. The underground power supply monitoring system in this paper carries out batches of controlled equipment in batches and implements batch communication. It solves the problem of low speed and long delay in fieldbus communication in medium and large scale applications, and solves the problem of equipment access with different communication protocols. The system has been proved to be reliable.