This paper presents the design process and application of a dual hardware hardware-in-the-loop (DHIL) testing platform targeting components and subsystems of wave energy conversion devices. The DHIL testing methodology combines two HIL-equipped test rigs allowing to simultaneously test components mounted on each rig and connected to the same simulation loop. The platform was therefore developed combining a HIL test rig for drivetrains with a HIL test rig for structural components.
The DHIL testing platform has the capability to address multiple types of tests on critical subsystems and components within a WEC: characterization tests, for defining key performances of the equipment under test; accelerated tests, to assess qualitative and quantitative reliability features; and ultimate load testing, for survivability purposes. The overall aim of these tests is to identify weaknesses in an early design phase of device design or as a qualification activity prior the deployment of an ocean prototype. Additionally, HIL and DHIL tests can be used to assess the influence of a design update on the overall WEC model and to track failure interdependencies at a relevant scale. Finally, all of the above-mentioned activities can inform the development of a more accurate global numerical model, potentially at sub-system / critical component level, to be validated based on the test results.
The definition of the test rig mechanical and electrical input specifications is dependent on the understanding of the load envelope each subsystem / component will be subject to during its lifetime. To define such envelope, a research activity modelling three different device types, three deployment sites and multiple design situations (e.g. power production, parked, shut-down etc.) led to the creation of a load database that was combined with information from WEC developers.
After defining the input specifications, the rigs were designed by identifying the optimal layout, the key components and the setup of the overall test area. Analyses on mechanical, electrical and hydraulic parameters were completed to ensure the required performance of each rig could be achieved, while guaranteeing the safety during their operation.
The signal processing of each rig was also analysed, with the aim of defining the minimum rig latency to allow HIL and DHIL tests to be performed. This analysis took into account the possible interface characteristics of the simulator, the sensors and the main features of the models used for real-time tests.
An overview of the testing activities to be conducted within the IMPACT project will be presented in this paper. Such activities aim to de-risking the technologies at early stages and increasing their maturity through a structured process. The proposed approach has the final goal of demonstrating that the DHIL testing platform is capable to reduce capital-intensive activities, often associated with the development of large-scale prototypes, which is a critical factor for the successful development and time-to-market of a WEC.