Real-time PLC implementations of fractional order operator

Abstract

The paper is intended to show a real time implementation of an elementary fractional order, integro-differential operator at PLC platform. The considered element is approximated with the use of known discrete PSE and CFE approximations. The operator we deal with is a crucial part of fractional order PID controller and another FO control algorithms. As an example the implementation at SIEMENS SIMATIC S7 1500 platform is presented. The both proposed approximations PSE and CFE were compared in the sense of accuracy, convergence and PLC execution time. Results of experiments show, that the PLC implementation of the fractional order element using the both approximations can be done with the use of object-oriented approach, the accuracy of approximation is determined by its order. The CFE approximation is much more faster than PSE and its accuracy is comparable to accuracy of PSE.