Model-based design process for product development of substation IEDs

The conventional process of developing protection algorithms for substation Intelligent Electronic Devices (IEDs) follows a V-development model of specification, design, coding, unit testing, integration, verification and validation. The code is implemented manually and is specific to a particular platform. This process is labour and time intensive, the source codes may also need to be rewritten or modified when a new platform is developed. Moreover, with the increased complexity of the protection algorithms, integrity requirements, short development time scales and rapid changes to the IED platform, the traditional approach is no longer efficient, reliable or cost-effective. A new approach has been developed and proven to improve the process efficiency by adapting a Model-Based Design (MBD) technique, which introduces a modelling concept at the design stage with a particular emphasis on reusability and platform independence. The model can be executed, verified and refined until it becomes the blueprint for the final implementation through automatic code generation. Software in-the-loop (SIL) and hardware in-the-loop (HIL) testing can be performed to ensure that the performance of the generated code is comparable to that of the model itself. The code can then be re-generated with specific platform dependent interfaces for integration and validation. Finally, the development of an over/under-power protection function is chosen as case study. The work consists of specification, modelling, testing and code generation. The generated code is integrated into an existing product platform to compare with the traditional coding methodology. The performance in terms of accuracy, execution speed and memory requirements are compared to the software produced by manual coding.