A Model based Toolchain for the Cosimulation of Cyber-physical Systems with FMI

Abstract

Smart Grids are cyber-physical systems that interface power grids with information and communication technologies in order to monitor them, automate decision making and balance production and consumption. Cosimulation with the Functional Mock-up Interface standard allows the exploration of the behavior of such complex systems by coordinating simulation units that correspond to the grid part, the communication network and the information system. However, FMI has limitations when it comes to cyber-physical system simulation, particularly because discrete-event signals exchanged by cyber components are not well supported. In addition, industrial projects involve several teams with different skills and methods that work in parallel to produce all the models required by the simulation, which increases the risk of inconsistency between models. This article presents a way to exchange discrete-event signals between FMI artifacts, which complies with the current 2.0 version of the standard. We developed a DSL and a model-based toolchain to generate the artifacts that are necessary to run the cosimulation of the whole system, and to detect potential inconsistencies between models. The approach is illustrated by the use case of an islanded grid implementing diesel and renewable sources, battery storage and intelligent control of the production.

The Smart Grid Simulation Framework: Model-Driven Engineering Applied to Cyber-Physical Systems

“…It also generates an execution script, which automates the build of all the FMU not yet generated, and the launch of the DAC-COSIM simulation. CosiML allows the distinction between discrete and continuous data exchanges, so that the provided generators can automatically implement our discrete-continuous encoding and decoding components [12] in the generated wrappers, and adapt the FMU inputs and outputs accordingly (each CosiML Port with a discrete variability causes the creation of two FMI ports). Our CosiML toolchain is meant to be extended with other generators to support more domain specific tools and to be used for cyber-physical systems other than smart grids.…”

“…One of the current limitations of FMI is its incompatibility with the manipulation of discrete signals, resulting in the absence of compatible Telecom simulators. To overcome this limitation, we have previously proposed in [12] a method to allow the exchange of discrete signals between several FMUs. It consists in an encoding component to transform a discrete signal into two time-continuous signals that can be exchanged over FMI, and a decoding component to perform the reverse operation and obtain the discrete-event signal from the FMI discretization of the time-continuous signals.…”