The changchangjiang nuclear power freshwater plant is a self-contained water plant of the nuclear power plant. It adopts two sets of redundant 400H control system and a remote extended rack. This paper describes the process requirements, control scheme, grounding, power supply, network, etc. The possible problems in the process of implementation are summarized. It adopts local manual control, remote manual control and PLC automatic control mode, and the level is from high to low. A total of four units have been planned for the Changjiang nuclear power plant. Phase I 1 and unit 2 have entered the detailed design stage. The changchangjiang nuclear power freshwater plant is a self provided water plant of the nuclear power plant. According to the demand of the total water consumption of the four units, the treatment scale of the freshwater plant is 16 000 m3/d and the water intake is 16 800 m3/d. Its buildings are divided into 10 sub-items: OF01: mixed reaction sedimentation tank, OF02: filter plant, OF03: clear water tank, OF04: water supply pump room and distribution room, OF05: drainage sludge tank, OF06: chlorination and medication room, thermostatic element OF07: sludge concentration tank and dewatering room, OF08: complex building, OF09: gate, OF00: outdoor [1]. The raw water from the water intake project is connected to the freshwater plant through two DN450 pipelines, and the pipelines entering the plant area are merged into one DN450 pipeline after the electromagnetic flowmeter is chlorinated into the water distribution well. The water is evenly distributed to two mixed reaction sedimentation tanks through the water distribution weir gate set in the water distribution well. Before entering the mixed reaction sedimentation tank, Micro-vortex tube mixing equipment is used for flocculation treatment. The flocculant is put into the dosing port of the Micro-vortex tube mixing equipment, and the coagulant is added after the mixing equipment. The dosing amount is adjusted according to the change of the original water flow and water quality after the mixed reaction sedimentation tank. The effluent is filtered into four-grid quartz sand filter separately, and the filtered water passes through clear jellyfish and enters into four-grid activated carbon filter for deep filtration and purification; the effluent of activated carbon filter is chlorinated and stored in two clean water tanks for domestic production, which are elevated by domestic water pump and production water pump and then sent to construction site for domestic water, main plant area for domestic water supply network, main plant area for production water supply network and freshwater plant.
Water use area such as self-use pipe network. In addition, the quantity of fire fighting water stored in the domestic and production water clarifier for freshwater plant area and the amount of water used for backwashing of the filter in the filter plant area are also included. In the system, a CPU cabinet with S7-400 main controller CPU414-4H is installed in the filter plant. There are five ET200M long-distance extended racks, including three filter plants, one mixed reaction sedimentation tank and one chlorination and medication room. A CPU cabinet with S7-400 main controller CPU414-4H is installed in the control room of the water supply pump house, with three ET200M remote expansion racks, including two water supply pump houses and one sludge dewatering room [2,3]. To realize the processing function of on-site switching signal and analog signal for the freshwater plant control system project of Changjiang Nuclear Power Plant.
In the control design of the filter plant, a double-circuit power supply cabinet and a CPU cabinet are arranged. At the same time, a S7-400 main controller CPU414-4H, an ET200M remote expanding rack and touch screen are installed in the CPU cabinet. They are mainly responsible for the detection and control of the technological parameters of the mixed flocculation sedimentation tank and the automatic control of the technological equipment, manual control, on-site control, equipment failure interlocking switching, start-stop, and so on. Barrier alarm and other functions. The analog signals of on-site switch and instrument are uploaded to the main control room of freshwater plant through touch screen local display and Ethernet Remote display. An expanding cabinet is arranged in the control room of the mixed reaction sedimentation tank, and a local expanding rack and touch screen are installed in the cabinet. Mainly responsible for the detection and control of process parameters and automatic control of process equipment, manual control, on-site control, equipment interlocking switch, start-stop, equipment failure alarm and other functions.
The analog signals of on-site switch and instrument are uploaded to the main control room of freshwater plant through touch screen local display and Ethernet Remote display. An expanding cabinet is arranged in the chlorination dosing control room, and a local expanding rack and touch screen are installed in the cabinet. Mainly responsible for the detection and control of process parameters and automatic control of process equipment, manual control, on-site control, equipment interlocking switch, start-stop, equipment failure alarm and other functions.
The analog signals of on-site switch and instrument are uploaded to the main control room of freshwater plant through touch screen local display and Ethernet Remote display. A double power supply cabinet and a CPU cabinet are arranged in the control room of the water supply pump house. At the same time, a S7-400 main controller CPU414-4H, two ET200M remote extended racks and touch screen are installed in the CPU cabinet. Mainly responsible for the detection and control of process parameters and automatic control of process equipment, manual control, on-site control, equipment interlocking switch, start-stop, equipment failure alarm and other functions. The analog signals of on-site switch and instrument are uploaded to the main control room of freshwater plant through touch screen local display and Ethernet Remote display. An expansion cabinet is arranged in the control room of the sludge dewatering room, and a local expansion rack is installed in the cabinet. Mainly responsible for sludge concentration tank and dewatering room on-site control room 2 part of the process parameters detection and control and automatic control of process equipment, manual control, on-site control, equipment interlocking switch, start-stop, equipment failure alarm and other functions. The analog signals of on-site switch and instrument are uploaded to the main control room of freshwater plant through touch screen local display and Ethernet Remote display. As shown in Figure 2. Working grounding and protective grounding are provided. The protective grounding (also known as safe grounding) is the grounding for personal safety and electrical equipment safety. The working grounding includes: logical ground, signal ground, systematic ground and shielding ground. UPS power supply is set up in each control room. Each control cabinet is equipped with open power supply to PLC and scanning voltage to field contacts, and the instrument power supply is distributed. Upper computer equipment also uses UPS to provide power.
Each type of power supply is equipped with independent power indicator lights, and each local cabinet is equipped with power indicator lights in the main control room of the freshwater plant. The power cabinet is designed to open the front and rear doors and go down the line. The three-layer control mode of on-site manual control, operator and engineer station remote control and PLC automatic control will be adopted for the control of main equipment; the other equipment will adopt two-layer control mode of operator and engineer station remote control and PLC automatic control.
Control level from high to low: local manual control, operator and engineer station remote control, PLC automatic. A PC equipped with STEP 7 software is called an engineer station.
It mainly completes the tasks of system hardware and configuration, symbol editing and program programming. Hardware configuration: Used for parameter setting of automation system and module. Network communication: data transmission for configuring MPI, PROFIBUS or industrial ethernet.
Symbol editing: Used to define symbolic names, data types and annotations, and to name physical addresses. Programming: Statement List (STL), Ladder Diagram (LAD), Functional Block Diagram (FBD) [5]. A PC equipped with WINCC software is called operator station. It mainly completes the functions of operator station picture configuration, variable connection, system alarm, variable curve generation and so on. This system needs to exchange data with the relevant equipment between chlorination and medication. It can use communication mode or hard wiring mode to complete the signal access. The PLC system is equipped with DP communication module, which is used to implement the DP protocol communication interface for other systems.
The PLC system is equipped with CP443-1 Ethernet module, which is used to realize the Ethernet protocol communication interface for other systems. Between the operator station and the engineer station is a ring network, and data sharing is realized through Ethernet between 212 switch and 204 switch and CP. As shown in Figure 3. Four touch screens communicate with each other through DP cable. The controller in the filter control room is far away from the mixing reaction sedimentation tank and chlorination dosing tank.
The controller communicates with the touch screen through RS485 repeater and active terminal. As shown in Figure 3. An engineer station and an operator station are set up in the main control room of the freshwater plant for data display, engineering configuration and maintenance control. Switches are set up in the main control room, and two industrial control computers are connected to the switches.
Each CPU is connected to the switches through the Ethernet module CP443-1, which constitutes the upper data display ethernet. Consider the distance between the main control room of freshwater plant and the cabinet equipment where the two CPUs are located.
If the distance exceeds 1000m, the use of optical fibers should be considered. This paper realizes the digital control of the water supply plant of the changchangjiang nuclear power plant by means of the redundant 400H controller, and realizes the automatic control on the spot and hand to meet the technological requirements. The possible shortcomings are that the control cabinet of the mixed reaction sedimentation tank and sludge dewatering room is front-door, and the on-site entry line may face the problem of cabinet space.
In addition, the filter controller also needs to communicate with the equipment of the chlorination and medication room.