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Automation of Gas Heated Furnace Using Ethernet Based Analog Input and Controller Modules Attila Kovács M.Sc. Student Gusztáv Szecső Dr. El. Eng. PhD. The Theoretical Structure of Control System of the Gas Heated Furnace • The Block Diagram of the Control System • System Models: K e s s / 1 G p s Process Dynamic – T2 s 1T3 s 1 The Resultant Dynamic Ka G a s of the Actuator and T1 s 1 Flow Systems (Gas and Air) - Controllers • General Controller y ( z ) A Bz 1 Cz 2 Dz Algorithm: x z 1 Pz 1 Qz 2 • Design Methods: - Dead-beat Controller – Dz yz q0 A z 1 G p z Bz d xz 1 q0 B z 1 z d Az z y 0 d d 1 T q0 b1 b2 bm Ts - PID-controller (velocity q0 q1 z 1 q2 z 2 algorithm) – Dz 1 z 1 - Feed-forward Controller Gs z H z 1 h0 h1 z 1 ... hl z l F z 1 1 f 1 z 1 ... f l z l Designing PID- and Feed-forward Controllers • Used Design Method: General Parameter Optimization Method Implemented in PIDCAD-software developed by G. Szecso • Designing Steps: – Finding Starting Points of the Optimization – Building up Database for the Optimization – Choosing Optimization Methods and Achieving Refinement – Algorithm Realization or Parameters Transformation for Real-time Applications (GENI or Intelligent PID- module) – Simulation and Real-time Testing Real-time Implementation of Controllers Algorithms • Implementing Dead-beat and Feed-forward Algorithms in GENI Basic-Script – Function Declaration public Function ztran(ube as single, a() as single, b() as single, be() as single, ki() as single) as single – PID-parameters Transformation to Industrial Standard Velocity Algorithm’s Parameters q0 q1 q2 K p AI Td System Realization I. Using by DAS-board Type Interfaces Without Feedforward Compensation blue: GeniDAQ red: MATLAB 1.4 1.2 1 0.8 0.6 0.4 0.2 0 -0.2 0 50 100 150 200 250 300 350 400 450 500 t s Applying Feedforward Compensation blue: GeniDAQ red: MATLAB 1.2 1 0.8 0.6 0.4 0.2 0 -0.2 0 50 100 150 200 250 300 350 400 450 500 t s System Realization II. Using Double-bus Type Intelligent Modules Results of Double-bus Control Structure Single-bus Control System Structure Results of Single-bus Control System Structure Conclusions Two computer languages were used to program the system, Basic Script for the programming of the GENI and C++ for the function library. A new series of problems emerged at this development stage. The documentations of the modules were inaccurate  or erroneous and the vendor provided function library is not able to make more than one TCP/IP connection at one time, which is a very serious limitation in this circumstances, moreover it was even a bigger problem because the system was not always able to build up the connections with its modules in time. Many of the ASCII commands , which purpose were to provide easier data acquisition and processing, were simply not working. Although to modernize the system with Ethernet based modules looked promising, the final result was much less satisfactory than we presumed. The inaccurate and nondescript documentation and the lack of help from the Advantech Technical Support made the development much harder than it was expected. The design of their function library seems to be flawed but we didn’t test the modules OPC capabilities. The system is properly working now, fulfilling the requirements set forward to it.
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