[Abstract] A simulation platform for ash and slag removal systems in thermal power plants was built by comprehensively utilizing a series of new simulation software, including PineCAD, EmulateControl, and iFIX. Reliable and effective online simulation modeling was performed on the sequential control circuit of the ash and slag removal system in thermal power plants. Experiments have demonstrated the good performance of the simulation platform, which has already been implemented in the operation training process of Huaneng Fuzhou Power Plant. This paper focuses on introducing the platform construction process and the comprehensive application of related software. 【Keywords】 New simulation software PineCad; Ash and slag removal system; Thermal power plant simulation; Simulation platform 【Abstract】 Using simulation software PineCad, EmulateControl, iFIX and a series of other software, I carried out simulation platform design on the system of eliminating ash and slag in large power plants and achieved good results. This article mainly focuses on the platform building process and the integrated application of the software. 【Keywords】 new simulation software PineCad; system of eliminating ash and slag; simulation of large power plants; simulation platform. 1 Introduction With the widespread application of distributed control systems (DCS) in thermal power plants, their automation level has greatly improved. In order to adapt to the resulting higher requirements for the operational proficiency of unit operators, thermal power plant simulation technology has emerged and developed rapidly. This paper takes the new configuration software PineCAD as the basic programming platform. In view of the power plant's requirements for high fidelity and convenient debugging of the simulation system, taking the ash removal and slag removal system of Huaneng Fuzhou Power Plant as an example, the simulation platform is built by comprehensively using the configuration software PineCAD, the virtual control station software EmulateControl, the data-driven software SIMComm, and the human-machine interface software iFIX[1]. Experiments have shown that the simulation system has basically achieved the expected effect, accurately and conveniently reflecting the on-site operation process, and has been put into operation monitoring and training work of Huaneng Fuzhou Power Plant. 2 Brief introduction of the ash removal and slag removal system of thermal power plant This system is an auxiliary system for the operation of power plant. It mainly completes the recycling and reuse of the flue gas and slag generated during the power generation process. The function of this system is to protect the environment on the one hand and reuse resources on the other hand to achieve sustainable development. The current ash and slag removal control system of thermal power plants mainly includes the following two aspects: 1. Pneumatic ash removal control system includes the control of the unit ash removal, compressed air, air drying and filtration, fly ash conveying and other systems; 2. Hydraulic ash and slag removal control system includes the control of the slag removal machine, flushing and ash pumping station, ash and slag pumping station, economizer ash hopper, air preheater ash hopper, connecting flue ash hopper and electrostatic precipitator ash hopper and other systems. Based on the above process considerations, we choose the sequential control method to carry out step-by-step control: the system establishes corresponding control stations according to the two programs of ash removal and slag removal, and designs control logic that conforms to the power plant process flow [3]. Since this paper focuses on describing the construction of the simulation platform, the specific logic design and writing process will not be further described. 3 Construction of the simulation platform 3.1 Overall construction idea The simulation development platform is completely based on computer design and has no special requirements for system hardware configuration. The basic hardware configuration is: (R)4 CPU 2.40GHz, 512MB computer; the basic system configuration is: Windows 2000 Server operating system. The software structure of the entire DCS simulation development platform is shown in Figure 1. The logic configuration data and model configuration data generated by the control configuration software are downloaded to the logic control station and object model station in the virtual control station, respectively. Data transfer between the model and control logic is achieved through data sharing software between the control stations. Data exchange between the human-machine interface and the virtual control station is implemented by dedicated data communication software. Note: A – Control configuration software; B – Logic control station; C – Model control station; DB – Logic configuration data; DC – Model configuration data; E – Control station data sharing software; F – Virtual control station and human-machine interface data communication software; G – Virtual control station; H – Human-machine interface configuration software. Figure 1. Software structure of the simulation development platform. In this design, as shown in Figure 1, A is the configuration software PineCAD; G is the virtual control station EmulateControl; F is the data-driven software SIMComm; and H is the human-machine interface software iFIX. 3.2 Virtual Control Station EmulateControl The virtual control station software EmulateControl is a control station specifically designed for simulation. It can be considered a virtual DCS hardware such as a PLC. Data transfer and sharing between different virtual control stations can be achieved through parameter settings. Working Principle: Configuration data generated by the configuration software PineCAD through analysis, compilation, and linking is output to the input data memory area of ​​the virtual control station. Simultaneously, the virtual control station calls relevant function algorithms from its own component algorithm library based on the algorithm characteristics of the input data memory area to perform calculations and outputs. Its structural principle diagram is shown in Figure 2: Figure 2 Structural Principle Block Diagram of EmulateControl Working Principle: Configuration data generated by the configuration software PineCAD through analysis, compilation, and linking is output to the input data memory area of ​​the virtual control station. Simultaneously, the virtual control station calls relevant functions or algorithms from its own component algorithm library based on the algorithm characteristics of the input data memory area to perform calculations and outputs. As can be seen from Figure 2-15, its component algorithm library mainly comes from three sources: custom function libraries, custom algorithm libraries, and third-party algorithm libraries. Calling mature third-party algorithm libraries greatly enriches the data processing capabilities of the virtual control station and also gives it greater flexibility. In this design, we established three stations for the control logic and simulation model, as shown in Table 1. All stations used the same execution time to achieve synchronization of data transmission. To correctly allocate data sources and flows, corresponding settings were made within PineCAD to allow data from different subsystems to be transferred between their respective stations. As shown in Figure 3: Table 1 Station Allocation List Figure 3 Station Settings within PineCAD The virtual control station EmulateControl has the following functions: 1. Setting the total number of control stations to run, simultaneously running the configuration logic of each station and realizing data transmission and sharing between control stations; 2. Setting the execution cycle of all control stations; acceleration or deceleration can be performed according to simulation needs; 3. For convenient debugging, inputs, outputs, and intermediate quantities can be monitored, and digital input points can be written; 4. It has a data saving function. For devices with long running times, the simulation data saving function can store transient operating conditions, achieving uninterrupted simulation. When resuming simulation, simply enter the monitoring state to restore the previous running results and continue the simulation. 3.3 Data-Driven Software SIMComm The data-driven software SIMComm can be considered as the I/O driver software provided by the hardware PLC manufacturer in the actual DCS system. This software is mainly responsible for data transmission between the human-machine interface iFIX and the virtual control station EmulateControl. It transmits and displays data from the virtual control station based on the "animation links" on the iFIX screen, while simultaneously transmitting the set values ​​and some switch quantities from the human-machine interface to the virtual control station as input for calculation. Its working principle is shown in Figure 4. Working principle: First, the output data of the virtual control station is read into the memory area by the read/write program. Then, according to a predefined address lookup table, the virtual control station database is converted to the iFIX database of the human-machine interface software. The iFIX database read/write program then writes the data to the iFIX database. Conversely, data set by the user in the human-machine interface is first written to the memory area by the iFIX database read/write program, and then the database conversion is completed according to the predefined address lookup table. Therefore, it can be seen that the key to the entire communication process, besides the two communication programs, is establishing the address lookup table. Figure 4. Working principle of SIMComm software. The virtual control station communication software is not only responsible for data communication, but also has functions such as data monitoring, real-time curve display, and range conversion. In addition, it provides a TCP/IP communication interface. 3.4 Configuration software PineCAD In this simulation system, the system's control logic and model configuration, as well as B and C in Figure 1, are all configured based on the configuration software PineCAD. This configuration software has rich instruction elements, and can also create new elements by directly applying mature third-party software such as the high-level language C language through dynamic link libraries according to actual needs. In addition, intuitive data monitoring methods, support for online parameter modification and stable online transmission functions, etc., can fully meet the requirements of the simulation development platform. 3.4.1 Introduction to basic elements The most important elements of PineCAD are the input and output elements that are directly related to data transmission. Among them, the input elements are divided into analog input AI, digital input DI, and intermediate variables TA and TD according to their nature; the corresponding outputs are AO, DO, TA, and TD. Except for intermediate variables used to store process data, which are implemented by temporarily calling memory space when necessary and do not require hardware allocation, all other input units must be carefully parameterized to ensure accurate and effective transmission. As shown in the right figure, this is the internal setting of a DI element, where the S parameter represents the source station receiving data, and the Ss parameter represents the index number of the element transmitting data. Therefore, the data source for this DI element is the DO element at station number 9. Simultaneously, to facilitate data flow tracking, the design intentionally sets the DI and AI numbers to be consistent with the sending DO and AO, achieving good results. 3.4.2 Introduction to Basic Control and Simulation Circuits The system successfully implements the control output and model input problem and the model output and control input problem using the communication principle between control stations: using the control output as the model input and the model output as the control input, thus forming a closed loop in the system. From an implementation perspective, the system structure becomes very simple, and the interface program between the model and control logic is eliminated, which also eliminates the need for simulation of the actual IO module. The simulation process is briefly described below using the grey water pump start-stop model shown in Figure 5 as an example: Figure 5 Grey Water Pump Start-Stop Model In the grey water pump sequential control model, when the control logic issues a start command DO001, the equipment model receives the start command via DI001. After performing an AND operation with the "NOT" of the equipment fault, a delayed "pump has started" signal DO001 is output. Then, DI002 in the control logic receives this signal, thus setting the start command DO001 in the control logic to 0. At this time, due to the reset priority instruction, the equipment output DO001 is locked to 1, thereby simulating the equipment start-up. If, after the control logic issues the start command DO001, the delayed instruction OND001 in the control logic has arrived, but the control logic still has not received the model's feedback DO001, then it is considered that the equipment start-up has failed, and the start-up fault DO002 is set to 1, thus completing the simulation of the equipment fault. The simulation of equipment shutdown is similar. 3.5 iFIX HMI Software The iFIX HMI software includes an HMI database, HMI configuration tools, and an HMI runtime platform. It provides a series of commonly used simulation functions such as system flowcharts, virtual consoles, operation sub-windows, trend charts, historical data display and query, data grouping display, alarm screens, alarm query and operation records, and reports. When creating the HMI screen, database establishment, screen configuration, and data linking are required, as follows: 1) Database Establishment First, the full address table and address range table must be established. The full address table essentially defines the meaning of each I/O point. This means that before programming, the meaning of each I/O point must be defined in advance. This is usually provided by the lower-level personnel and formatted according to a specific format, using Microsoft Excel to create a database file "*.CSV". Second, the SM2 driver file must be established: The I/O driver is the interface between iFIX and the process hardware. The purpose of I/O Driver Configuration is to link the PLC address with the iFIX database address. Finally, import the "*.CSV" file using the database manager. In the database manager menu bar, select "IMPORT" under the FILE item to import the "*.CSV" file, thus creating the database. 2) Screen Configuration: Screen configuration involves configuring the screen flow using the original screen configuration elements provided by iFIX. It's relatively simple; just follow the process flow. This will not be discussed further here. 3) Data Link: To achieve real-time monitoring of the configured iFIX screen, data linking is necessary so that the screen displays a value of a defined point, such as the current value. Data linking is simple: it links the point to a point in the database. Depending on the display requirements, static display settings are used for elements that require direct display of data from the lower-level machine on the screen; dynamic display settings are used in animation production for elements that require displaying color or other state changes. The following is a diagram of the completed pressurization system and storage discharge system: Figure 6 Diagram of the pressurization system and storage discharge system. In the actual debugging process, a simulation effect close to the actual situation can be obtained according to the corresponding component names, the status of their indicator lights and the data displayed. By using the buttons and controlling the on-site operation, the system mechanism can be mastered and the training effect of the power plant trainees has been achieved. 3.6 Sequential control circuit simulation Thermal power plant equipment is divided into two categories according to its own characteristics: sequential control model and analog quantity model [5]. The sequential control model mainly simulates the start-up and shutdown and switching status of the equipment. It requires that when there is an open signal, the equipment model can feed back an open signal to the control logic after a delay. The logic can then know the operating status of the equipment based on the status of the feedback signal. It is relatively simple and the model is relatively simple. In this design, the sequential control model is mainly involved. The ash water level control is used as an example for explanation. In this control process, it is necessary to collect signals from the model station about whether the ash water level has reached the limit [6]. The control station first sends a simple grey water pump start signal to the model station. Based on this signal, the model simulates the actual grey water pump start-up phenomenon in a virtual state and directly translates it into changes in the grey water tank level. When a water level alarm signal occurs, the model station sends this signal back to the control station, serving as the direct basis for the control station's next control strategy change. The grey water tank level in this design is a simple single-slope change. The main factors causing the water level change are the original water volume in the grey water tank and the grey water pump flow rate. A two-condition slope tracker (TRM) can be used to simulate the water level. The grey water tank level control simulation is mainly used to determine the grey water pump tripping conditions, i.e., the pump will start within 5 seconds after the shaft seal water flow switch is opened, or the grey water tank level is less than the set L2 value, at which point the grey water pump will trip. To determine the interval between the switch and the pump start-up, a timing circuit composed of a pulse counter (CNT) was designed, as shown in Figure 7. The control process is as follows: 1. When the shaft seal water pump is turned on, since "C1A Grey Water Pump" DO039 is not running, and with the action of the inverter (002) and "AND gate" 003, a continuous high-level signal is sent out; subsequently, due to the clever use of "AND gate", the pulse counter port 1 (counting terminal) begins to record the pulse signal generated by the pulse trigger; 2. Since the "C1A Grey Water Pump Running" DO039 signal is set to 0, under the action of the "switcher", the "original water level of the grey water tank" is maintained at the set initial value SG002; Figure 7 3. After the "Grey Water Pump Operation" signal is activated, the "C1A Grey Water Pump Operation" DO039 output is one. Due to the action of the "Inverter" 009, the subsequent "Falling Edge Pulse" element 001 detects the falling edge, thus outputting a high level for one cycle, followed by a low level output. According to the characteristics of the TRM element, the TRM element output value is first set to the "original stored water level in the grey water tank," and then tracks the change in the value of SG10 (internal setting value is 0) with the "grey water pump outlet flow rate" as the rate of change, i.e., it decreases. 4. If the "Grey Water Pump Operation" signal appears too early before the time specified in the control procedure, the pulse counter's measurement value is too small. After passing through the high/low limit judgment unit, an alarm signal is output, thus realizing the entire alarm process. Many sequential control models in this design adopt the above design method. This method is simple and easy to implement, and at the same time, it has the characteristics of being fast and accurate in actual debugging. 4. Simulation Effect Evaluation and Application Prospect Analysis The simulation platform designed in this paper can be extended to the design of related simulation systems and has strong versatility. Meanwhile, the simulation system was used to implement the upper computer simulation operation and the on-site data simulation acquisition, and the experiments have achieved good results. By using the above simulation system, the detailed process of the actual operation of the unit can be well grasped, which is very suitable for training unit operators; at the same time, by timely obtaining real-time data similar to the field, the unit status can be accurately grasped and the danger can be eliminated in time. As a training platform for on-site operators, it will effectively improve their ability to respond to danger in actual work; finally, as a simulation system, its accuracy and reliability have also met the needs of control strategy research and equipment modification. It is believed that this system will be widely used in thermal power plants, training institutions and even research institutions. References [1] PineCAD 4.X software user manual [S]. Beijing Huaneng Information Industry Holding Co., Ltd. [2] FZA-ASH016 Phase I Ash Control System Operation Manual [S]. Fuzhou Fuda Automation Technology Co., Ltd., June 2004 [3] Chen Zonghai. Process Control System Modeling and Simulation [M]. Hefei: University of Science and Technology of China Press, 1997, 81-99 [4] Song Fugen. Simulation Research on Boiler Side of Thermal Power Plant Based on New Simulation System [D]. Master's Thesis of School of Electrical Engineering, Fuzhou University, 2005, 35-40 [5] Tang Shilin. Computer Simulation Technology of Power Plant [M]. Beijing: Science Press, 1997, 67-77 [6] Lü Chongde, Ren Tingjin et al. Simulation and Modeling of Large Thermal Power Unit System [M]. Beijing: Tsinghua University Press, 2002, 48-68 The appendix figure shows the port mode built into PineCAD software, where the port number corresponds to the port arrow. 2. Brief description of PineCAD components referenced in the circuit diagram