Implementation of a Processor-in-the-Loop System for Comparison of Synchronization Algorithms

To guarantee the adequate interaction between controllers and systems to be controlled, it is imperative that the design, implementation and testing of control algorithms are performed. It is not always posible to have the actual plant for initial testing, algorithm debugging and controller adjustments, because of safety and economical and operational considerations. Using scaled plants is costly and time-consuming and it does not completely eliminate the inherent danger of disruptions and failures caused by the testing of algorithms. A major drawback of testing is the imperative need for interaction between the controller and the plant to be controlled, in order to achieve reliable and safe controller settings. To overcome this drawback, there are different alternatives; among them, the processor-in-theloop (PIL) approach, which allows the observation of more realistic performance of the algorithms at an affordable cost. This paper presents an implementation guide for the PIL approach between Matlab / Simulink and Texas Instruments' C2000 family control hardware. This approach is applied to the evaluation of synchronization algorithms for distributed generation units. In particular, two algorithms for phase-locked loops (PLL) are considered: DSOGI-PLL and DSOGI-PLL with FLL; the Matlab / Simulink PLL is used to validate the implementations. The PLLs are processed in a digital signal controller (DSC) and electrical power system are implemented in Simulink.