[Abstract] This paper details the performance and characteristics of TPS (Transformer Power System) and discusses the application of Honeywell's TPS system in a circulating fluidized bed (CFB) boiler, based on practical experience in an enterprise. The control of electrical equipment and the optimization of main steam are analyzed and discussed. A design and implementation plan for the TPS system is proposed. This is a typical application example of a DCS system in a main-pipe CFB boiler, with high promotion and reference value. [Keywords] TPS system, circulating fluidized bed boiler control, MODBUS Communication 1: Overview The efficient and low-pollution application of energy has become a common goal pursued by countries worldwide. With the gradual improvement of national environmental protection policies and the increasing environmental awareness of the public, clean coal combustion technology, especially circulating fluidized bed (CFB) boiler technology, has developed rapidly. CFB boilers, with their wide fuel adaptability, in-furnace desulfurization, low NO emissions, high combustion efficiency, large load regulation ratio, and comprehensive utilization of ash and slag, have become the main development direction of clean coal combustion technology, and are therefore increasingly widely used in industries such as power, heating, and chemical production. With the continuous development of the number and capacity of CFB boilers, the automatic control of large-capacity CFB boilers has also become a hot topic in the industry. From the perspective of the process characteristics of CFB boilers, like conventional pulverized coal boilers, they exhibit characteristics of multi-parameter, nonlinear, time-varying, and tightly coupled multivariables. Furthermore, CFB boilers have more input/output variables and more complex coupling relationships than ordinary boilers. II: Specific Application of TPS System in Thermal Power Automation Devices 1. System Selection, Introduction, and Configuration To meet control requirements, the designed regulating systems are all complex control systems. Conventional automation schemes and devices rarely achieve ideal control results. Therefore, the control of circulating fluidized bed boilers in China generally adopts DCS control. We use Honeywell's TPS distributed control system. The TPS system is a plant-wide integrated management and control system launched by Honeywell based on the TDC-3000 system. It introduces the latest computer system hardware and software technology platform while maintaining the original reliability, real-time performance, and flexibility. In terms of network structure, the TPS system adopts a three-layer network (PIN, LCN, UCN) framework, each layer performing its respective function, and the network transmission medium uses redundancy technology. In terms of functional components, the system operator station can be configured in multiple ways, providing redundant backups for each other; the controllers and I/O modules of the field control station can also be redundantly configured, ensuring smooth switching of the control system in case of failure; the fully redundant configuration of the system communication interface module improves the system's fault tolerance. Regarding system hardware, special board manufacturing and coating protection technologies are used, allowing the system to operate in harsh environments; the system software's self-diagnostic functions and automatic fault handling functions greatly facilitate system maintenance. The GUS operator station uses the Win2000 operating system, and application software can exchange data with the operator station via network DDE, OPC, etc., improving the system's openness. In the entire TPS system, a common HM (History Module) is configured to store the system files, attribute files, user configuration files, and historical data of process parameters for the entire system; two pairs of redundant network interface modules NIM (Network Interface Modules), network numbers 03 and 04, are used to connect the HPMMs of boilers #11 and #12, unit #4, and boilers #13 and #14, unit #5, respectively. Six GUS operator stations are configured in the control room for operators to monitor and control the entire production process, one engineering station is used for configuration and debugging, and one APP contact is used for connection to the production management network and data acquisition and transmission. A pair of redundant HPMM (High Performance Control Module) controllers are used for data acquisition and control. The overall system configuration structure diagram is shown in the figure. 2. Main Functions of the System in the Unit Control System The thermal power TPS system mainly includes DAS, SCS, MCS, FSSS, etc. Its successful application has realized real-time data acquisition, process control, sequential control, alarm control, monitoring, operation, and remote data transmission functions in industrial production processes, improving the overall automation level, optimizing operating conditions, and stabilizing production. 3: Continuous Loop (MCS) Control Function The main steam pressure regulation system has three control methods: cascade (CAS) mode, automatic (AUTO) mode, and manual (MAN) mode. The cascade control mode adopts the direct energy balance regulation method; the automatic control mode adopts the direct energy balance regulation method. Its working principle is introduced below. 1) Indirect Energy Balance Regulation Principle and Implementation: For boilers operating under a main control system, since there is no simple direct correspondence between energy supply and demand between the boiler and turbine, boiler load regulation typically employs an indirect energy balance control method. This involves using the main steam pressure signal, which reflects the energy balance between the boiler and turbine, as an indirect energy signal reflecting the boiler's output. The required combustion rate (coal quantity and combustion air quantity, etc.) on the boiler side is calculated and controlled through regulation calculations to meet the turbine's output requirements. The automatic control (AUTO) mode of the main steam pressure regulation system is designed for this regulation method. It consists of a main regulator, a secondary regulator, and four automatic/manual operation stations (A/M). The main regulator receives the main steam pressure signal from the boiler outlet as a measured value and calculates the required coal quantity for the boiler based on the main steam pressure setpoint provided by the operator. The secondary regulator, acting as a coal feed rate regulator, ensures that the coal feed rate entering the furnace meets the value calculated by the main regulator and promptly eliminates the impact of coal quantity disturbances on the main steam pressure. It uses the actual coal feed signal from the boiler as the measured value and the output of the main regulator as the coal feed setpoint to calculate and send speed adjustment commands to the four coal feeder frequency converters. The A/M operation station for the speed of the four coal feeder frequency converters is used by operators to directly adjust the speed of the coal feeder frequency converters in case of abnormalities in the main steam pressure regulation system, thereby adjusting the coal feed rate. The four coal feeder frequency converter speed A/M operation station has an offset setpoint input function, allowing for fine-tuning of the speed of each coal feeder frequency converter after multiple coal feeder frequency converters are simultaneously put into automatic control mode. To promptly reflect and effectively adjust the boiler fuel calorific value in advance, the main regulator introduces the differential signal of the steam drum pressure as one of the feedforward signals; simultaneously, considering the influence of the coal feed rate entering the furnace on the bed temperature, a bed temperature deviation correction function signal is also introduced into the feedforward channel of the main regulator. When the positive deviation of the bed temperature is large, the coal feed rate entering the furnace is appropriately reduced; conversely, the same applies. The indirect energy type main steam pressure regulation system is shown in Figure 1. 2) The direct energy balance regulation principle and the cascade control (CAS) method for the main steam pressure regulation system adopt this regulation principle. Structurally, this control method adds a boiler load distribution calculation loop to the indirect energy balance regulation method, but its regulation mechanism differs somewhat from the former. See Figure 2. The function of the boiler load distribution calculation loop is to calculate the total demand for main steam on the turbine side based on the turbine load (including power generation load, first-stage extraction steam volume, and first-stage desuperheating and pressure reducing steam volume). Then, based on the load distribution quota undertaken by each boiler in the main control system (set by the operators), it calculates the fuel quantity corresponding to the required steam volume of each boiler. Finally, the main steam pressure regulation system in each boiler adjusts the required fuel and air volume for this load quota. The boiler load distribution calculation loop mainly consists of three levels of regulators. The first-stage regulator calculates the steam required for the turbine power generation load and the first-stage extraction steam volume. The second-stage regulator calculates the total turbine steam demand, including the first-stage desuperheating and pressure-reducing steam volume. There are two third-stage regulators, which calculate the fuel quantity corresponding to the steam required for boilers #11 and #12, respectively, and then send them to their respective main steam pressure regulation systems for regulation. The main steam pressure regulation system uses external logic control in CAS mode. With the change of control mode, the original main regulator of the main steam pressure regulation system is replaced by another one. The function of this regulator is changed to correct the boiler main steam pressure. The fuel quantity signal calculated by the boiler load distribution calculation loop is used as the main regulation signal of the main steam pressure regulation system at this time, and enters the feedforward channel of the main regulator along with the drum pressure differential feedforward signal and the bed temperature deviation correction function signal. The subsequent regulation mechanism is the same as that described in the indirect energy regulation principle. 4: Sequential Control (SCS) Function The sequential control (SCS) function is for the operation control, interlock protection, status monitoring and abnormal alarm of pumps, electric gates and remote control equipment related to the boiler and turbine. The boiler-side SCS function of the DCS system at Hengtong Chemical Thermal Power Plant also includes the Boiler Safety Monitoring System (FSSS system), boiler master interlock, and ignition programmable control. Here, we will use the control and protection of boiler fans in the Sequential Control System (SCS) as an example to illustrate the powerful control functions of the TPS system. The principle block diagram of the fan logic control is as follows: In the logic design process, to ensure safe and reliable fan control and reflect the actual fan control process, coordinated control signals for the fan are introduced. These include operation status permission, interlock engagement permission, fan switch status feedback signals, local/remote control status, and other interlocking device status signals. During actual fan operation, the operator can visually observe the fan status through a small panel on the CRT (as shown in the figure). When starting the fan normally, the "Disable Operation" button should be turned on first, and then the control mode should be switched to remote control. At this time, the "Fan Local/Remote Control" status light on the small panel should turn red. Finally, pressing the "close" button will, if all logic configuration conditions are met, send the control signal to the field fan via the intermediate relay, and simultaneously return the fan's operating status signal. If the fan is not running, a "closing failure" message will appear on the CRT; otherwise, the "closing" button will turn red. During "interlocking activation" control, if a fan trips due to an accident while normally operating, and both primary air fans are running, the other standby fan will automatically start to maintain normal boiler airflow, ensuring safe and stable boiler operation. 5: Communication between the TPS system and the DEH system. Based on the company's development needs, in 2002, Shanghai Xinhua's DEH (Digital Electric-Hydraulic Control System) was introduced into the turbine control island of the 60MW unit. The DEH system is a digital electro-hydraulic control system independently developed by Xinhua, featuring high sensitivity, high steady-state accuracy, fast dynamic response, and easy system expansion. It successfully enabled the stable operation of our company's two 60MW units offline. However, due to the different network structures of TPS and DEH, direct data sharing is difficult. After multiple analyses and studies, we developed a method to send data to DCS via Gateway (GTW) software on the DEH gateway machine. GTW software is a standard interface specification provided by Xinhua Company to users based on its XDPS system, using the XDPS real-time database VC++ 6.0. Various interface software programs are developed according to this specification. When the DEH system software is running, the GTW executable file modbus2.exe is executed on the MMI contact, sending data to TPS via the Modbus communication protocol in a virtual PLC manner. The data is then sent out through the computer's serial port. However, because the serial signal interface card in the DCS uses the RS-485 protocol, the data must be converted from RS-232 to RS-485 to be received. At the DCS end, only one SI-serial signal interface card is needed to receive the data. The data is read from the HPM in the form of array points and sent to the operator station, and then transmitted level by level to different control and management systems. Its schematic diagram is as follows: III. Conclusion: The powerful functional modules and superior performance of the TPS control system ensured that the project was put into operation within the predetermined time according to the design plan and operated without faults. Its control accuracy fully met the production requirements. HONEYWELL's TPS system has broad application prospects in circulating fluidized bed boiler control and power plant production of different scales. It also lays a solid foundation for our company's independent grid operation mechanism. We must continue to research and develop the potential of the TPS system to better prepare for integrated management and control.