Towards Digital Twins for Safety Demonstrations : Interfacing Strategies for Fpga-Targeted Applications

Increased digitalization and electrification efforts are ongoing in the subsea oil and gas industry. One proposal for electrification, utilized as a case study in the project of digital twins for safety demonstrations, is an all-electric actuation system. In the event of an emergency or production shutdown the system actuates the closing of a safety valve, shutting the flow of hydrocarbons and transitioning the system to a safe state.The all-electric actuation system reliant on opportune and correct execution of the control logic. Digital twins for safety demonstrations of the safety-critical all-electric actuation system will require interfacing the control logic with the digital twin. A target device for certain functionality of control logic is an field programmable gate array (FPGA). An FPGA can realize control algorithms by implementing the functionality in digital logical circuits, enabling fast and hardware-accelerated execution of the all-electric actuation system. The device is programmable in the field, updates of the control logic once the physical asset is operational are possible. The standard IEC 61508 recommends a development flow for applications targeted for FPGA and to use a hardware description language (HDL) writing descriptions of the circuits to configure the FPGA. Due to the inherent parallelism of the target device, the strategies for interfacing a digital twin of the all-electric actuation system with the controllers targeted for FPGA require certain considerations. This article describes characteristics of the device, such as the inherent parallelism, the properties of HDL and the available tools. Based on a theoretical review of FPGA devices, this article presents three potential interfacing strategies for covering the recommended development flow. Evaluation criteria from identified values of digital twins are described, and by incorporating the recommendations of IEC 61508 this article evaluates and recommends strategies for interfacing a digital twin with FPGA-targeted functionalities. It is recommended to perform complete safety demonstrations of the control logic at the behavioral design of the control logic and once the control logic is implemented on the FPGA device. Furthermore, an FPGA-based digital twin is considered the best strategy for safety demonstrations of the FPGA-implemented control logic. Verifying the recommendations using a case study, is the next step toward digital twins for safety demonstrations