1, nuclear power plant instrument control system
Nuclear power plants full digital control system is mainly composed of a conventional meter control TXP (Opera-tional I & C System) and safety instrumentation TXS (Safety I & System C) in two parts, the main purpose is for monitoring and controlling nuclear release thermal power plants and production of electrical energy The main and auxiliary processes, in all operating modes including emergency, maintain the safety, operability and reliability of the power plant, and ensure the economy of the power plant under normal operating conditions.
PROFIBUS is a simple, rugged and reliable fieldbus system, and the only fieldbus that can be applied to all fields in a standard manner and throughout the process chain. As shown in Figure 1, data communication in the instrument control system is completed by the power plant bus and fieldbus, the SLNEC H1 FO bus, and the PROFIBUS bus system completed. The terminal bus is used for communication between PU / SU and OT and ET and DT and interconnects through the gateway / bridge and external public network. The power plant bus is used between the AS62O, OM690, ES680 and DS670, and connected to the terminal bus through the gateway, connected to the industrial Ethernet bus of the security instrument control system. Data communication includes transmission of all data and commands in nuclear power plants, specifically involving instrument control systems for security systems, security systems for security related systems, and instrument-control systems for normal operation systems, completing between different systems or in the same system. Information transfer between different components, and communication tasks with other external systems. The data transmission medium uses a fiber optic cable that is not sensitive to electromagnetic interference.
2, SINEC H1 bus
Slnec H1 structure with linear industrial Ethernet, which is based on IEEE802.3 (Ethernet) standard, is a bus type system, involving physical layer, data chain in ISO / OSI open system interconnected network model. Road and transport layers. It uses the CSMA / CD bus access technology, and the transmission interface complies with the LSO 80733 transport protocol. Therefore, the SLNEC H1 LAN is in line with the model structure of the local area network, which is the industrial application of these standards. Figure 2 The median coupler is connected to the gateway to connect TxP systems with the power plant bus of the TXP system, and the star coupler is connected to the MSL (surveillance service interface) and SU (service unit), MSL (monitor service interface) And the connection between the drive computer, the SU is an important communication device of T × S, which is mainly: cyclic acquisition data, mirror management of data for data for the MSL and automatic control, provides user interface for the application, will apply the application The instruction is transmitted to a real-time operating environment or transmits feedback signals of the instruction to the application.
3, SINEC L2 bus
The SLNEC L2 fieldbus uses the PROFIBUS bus system for connecting digital field devices and field equipment to the power plant bus, with data transfer speeds of 1.5Mbps. SINEC L2 network can be divided into shielded twisted pair (Slnec L2TW), fiber (SLNEC L2FO), a combination (SLNECL2TVV / FO), and Slnec L2TVV generally adopt a bus structure, and the node is passed through a bus terminal or The bus connector is connected to the bus, and each network segment can have up to 32 nodes. The various network segments are connected through the repeater, and can connect up to 127 nodes through the repeater, and must not exceed the seven relays between any two stations. . L2 network of a single structure, if the baseband transmission, the RS485 bus standard, the farthest distance is 1200m. Such as driven computers and field drive mechanisms, signal acquisitions and functional processing computers and redundant signal acquisitions and functional processing between computers. The SLNEC L2 bus technology features and network protocols are four Slnec network series, which have been introduced early in Siemens include four of SLNEC S1, SLNEC L2, SLNEC H1, SINEC H3. SINEC L2 is an industrial bureaux for medium and small, which is based on German fieldbus standard PROFIBUS defined by the German Standardization Association DIN1925, which is in line with an OSL (open system reference model) of international standardized organization. Widely used in discrete control.
4, application of PROFIBUS fieldbus system
4.1 Hardware structure design of T × S system data communication
T × s data communication is mainly completed by the two communication modules of SL21, SCP1 (as shown in FIG. 2), and when the security instruction is transmitted in a redundant channel or transmitting between the redundant channels, the SL21 is responsible for the redundant channels between the redundant channels. Processing Module (SVE1) communication, SCP1 is used to transmit data transmission with industrial Ethernet, and can also be used for MSI (monitoring service interface) or Gateway communications with other information systems. Since the main process equipment of nuclear power plants includes reactors, one loop, steam generator, secondary loop, regulator, pump, etc. The main measuring device comprises a detecting neutron flux, pressure transmitter, pressure transmitter, liquid level, flow meters, temperature and the like; a large number of additional electric control valve, solenoid valves, motors and the like. Such systems can use the PROFIBUS bus to complete the monitoring task. We know that the field data acquisition system has a digital signal, an analog signal (4-20mA), from the standard signal acquired by the field, and sent to the signal processing unit after the signal processing unit is logically processed, and then the logic processing unit passes the SINECUS of PROFIBUS. The L2 BUS is transmitted to the four-to-two logical voting unit because the system uses a redundant structure, and the logical voting unit transmits the vot signal to the priority module AV42, drive actuator by the priority module.
4.2 T × S system data communication software design
4.2.1 PROFIBUS
PROFIBUS is a standardized independent user bus system for underlying communication. The techniques used are applicable to most communication devices. According to different requirements, PROFIBUS has different protocol content. T × S is used prciFibusfdl, mainly because T × S four-channel redundancy requires independence and diversification of all signals, and can simplify the agreement.
4.2.2 Gateway's software design
The main communication software in the TXS system runs on the Gateway (as shown in Figure 3), executed in the output program of TXS in GATEWAY, and stores some functions from the MSI signal in the buffer, which can be used by some functions of the database. Read it. The runtime is controlled by real-time environmental control, and the real-time environment is used to communicate with the DLPI database. The TXS output program does not occupy the calculation time of all Gateway, some of the calculation time is the operation of the converter, converts the signal of TXS to the data format of TXP, so that the related device calls.
The synchronization task of the converter requires the conversion program and TXS's real-time running environment (ie, running in the same cycle) and utilizes the DLPI database to obtain process data or transfer the operation information to the appropriate system. Process Data is stored in a buffer (PI bufer), which is also used to store manifer commands or process signals from TXP, and also manage information columns. Control Table is used to define the storage area in the PI buffer, read the control table by some instruction translators. The non-synchronous task of the conversion program is to refer to it and the TXS system is not synchronized. Mainly completes the data in the PI buffer to the transmission of the process data block, or the transmission of data in the process data block to the PI buffer. The transmission and reception of this process data block is performed in accordance with the non-synchronous task request.
5. Application status and development prospects of PROFIBUS fieldbus system
The power industry is a very high level of automation, such as host DCS systems, nuclear security control systems, and major auxiliary program control systems. These systems have high reliability requirements, monitoring equipment, and more complicated, real-time requirements. . In particular, the host DCS system involves hundreds of pressure and differential pressure transmitters, hundreds of electric or start execution agencies, hundreds of temperature measuring points, and the system should perform complex closed loop control, cascade control, trichring control, Ratio control, to perform device chain control, to perform complex reactive piles, APC, neutron flux control. All of this requires high reliability control systems to ensure the safety, stability and reliability of the entire production process.
Currently, the control system based on fieldbus is currently applied to the application of power plant. The following aspects include the following aspects: 1 Supporting the intelligent equipment of the fieldbus causes initial investment; 2 Some equipment and instruments do not bring bus interfaces; 8 which equipment, instrument information can be transmitted 4 How to change the system structure, how to construct a control system based on fieldbus; 5 communication is reliable; 6 Detection of device selection.
For new nuclear power plants, the conditions of the instrument, actuators, inverters, intelligent motor controllers, valve locator, etc. with bus interfaces are already mature, as many well-known instruments, equipment manufacturers such as: Siemens, ABB, EMERSON, etc. A variety of systems and devices that can be selected, and the price is also increasingly close to the conventional smart device. Moreover, the structure based on the HART protocol connection transmitter has been applied in many power plants, and the user's praise is obtained in centralized verification, increasing collection accuracy. The fieldbus is a more comprehensive bus than the HART protocol, so it has better application prospects. Fieldbus systems can be used in the new power plant, FGD DCS, and auxiliary program control systems, and there are many very successful applications.
For old nuclear power plants, the PROFIBUS can also provide a good solution for such systems for a large number of non-intelligent instrumentation and executing agencies. The remote I / O method can be used, and the non-smart meter is acquired by a regular I / O module, and then connected to the central controller via the PROFIBUS-DP bus. The instrumentation and actuators can be replaced by the equipment life cycle.
6, conclude
The PROFIBUS bus has many applications in the domestic power system. The T × S system adopts the PROFIBUS-DP bus structure with the PROFIBUS bus, the DCS system of Shandong Liutai Power Plant and the main plant of Huaneng Yuhuan Power Plant.
Editor in charge: GT, read full text
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