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DIAMOND Résumé de rapport

Project ID: 621208
Financé au titre de: FP7-JTI
Pays: Netherlands

Periodic Report Summary 1 - DIAMOND (Diagnosis-aided control for SOFC power systems)

Project Context and Objectives:
The DIAMOND project aims at improving the performance of solid oxide fuel cells (SOFCs) for CHP applications by implementing innovative strategies for on-board diagnosis and control. Advanced monitoring models will be developed to integrate diagnosis and control functions with the objective of having meaningful information on the actual state-of-the-health of the entire system. The new concepts will be validated using two different SOFC systems.

Project Results:
The ultimate objective of the project is to contribute to SOFC systems reliability and durability through design and implementation of a hierarchical control system supported by fault diagnostic system on two different SOFC CHP systems, one conventional and the other advanced. To achieve this the work has been conducted along several tracks.
Firstly an inventory of the functional system requirements, current has been performed. Related to that a review of the of currently practiced control and diagnostic has been undertaken.
A thorough inventory of faults and failures which might occur in SOFC CHP systems has been made. The most important ones like, for example, high fuel and air utilisation, leakages, too high temperatures and out of specification steam to carbon ratios, will attract particular address of the project team. By using fault-tree analysis for the DIAMOND C system, a fault signature matrix is constructed. This is essential the detection and isolation of faults at system level. System diagnosis relies on mathematical models associated to the system components. The models were validated by using existing data from the DIAMOND C system. Furthermore, signal based algorithms were developed, a statistical method for the detection of changes in residuals, which are the difference between measured and modelled data.
To determine high fuel and air utilisation the applicability of Total Harmonic Distortion Analysis is investigated. Results show that at high fuel utilisation the response to a sinusoidal perturbation on the stack voltage or current results is distorted at the low frequencies. The response is a function of the utilisation, amplitude of the perturbation and frequency. Preparations have started for implementing this method in a controller.
In the forthcoming commercial systems the number of physical sensors will be kept at the minimum to reduce costs. Consequently, there is a need to deduce critical parameters from known parameters. The so-called soft sensors have been developed and validated for the DIAMOND C system, in particular to reconstruct the minimum and maximum stack temperature as well as the oxygen to carbon ratio.
Low-level controllers for the SOFC power systems were designed by combining feed-forward and feed-back approach. The controllers were tested on a nonlinear SOFC stack model developed by UNISA. The low-level controllers were upgraded with a supervisory optimizer. The goal of the optimizer is to calculate set-points for the low-level controllers in a way to maximize the electrical efficiency of the system while satisfying a number of constraints. The supervisory optimizer was designed for the SOFC stack model.

Two systems are used within the project; the conventional DIAMOND C system based on an existing system and an advanced system using a highly integrated HoTbox. The practical implementation of both systems was delayed for different reasons. However, for the DIAMOND C system experimental data were timely provided to the partners. The DIAMOND A system has been tested using a HoTbox with dummy stacks for safety reasons. Conventional controllers has been implemented to test the system.

For the sake of dissemination a newsletter has been set up and three issues so far have been disseminated to ta number of parties in industry and academia. In that sense a workshop is organised for the dissemination of the project accomplishments.

Potential Impact:
The lack of sufficiently developed system control and diagnosis tools for SOFC CHP systems and technology is one of the main hindrances on the path to a wide-spread market deployment of such systems. DIAMOND addresses this issue. The project will develop diagnostic and monitoring tools which enable to evaluate the state of health of a system, and an advanced control taking into account the state of health. These results will promote both the European SOFC CHP technology development and the business around it. This is also the primary objective of the whole AA3 (Stationary power generation & combined heat and power (CHP)) application area as described in the FCH JU annual implementation plan.
The activities within DIAMOND will push forward the level of scientific knowhow related to fuel cell system control by developing and disseminating novel means for automatic monitoring, control and diagnosis for SOFC systems.
The development and validation of methods and techniques for detecting BoP component failures and faults, as well as for monitoring the system state of health are at the core of DIAMOND.

The DIAMOND project includes clear means to evaluate the developed algorithms’ effect on the systems’ operation and expected lifetime. Furthermore, the starting point of all algorithm development work in DIAMOND is that the algorithms are implementable in standard industrial controllers, thereby guaranteeing their applicability to mass-produced products. Similarly, the integration of diagnostic and control algorithms to the systems, is a key characteristic of the DIAMOND project work. The algorithm evaluation tests carried out in DIAMOND enable estimating the effect of the developed algorithms on the systems’ lifetime and thus how the project outcomes are positioned against the market expectations for SOFC CHP systems. Also the costs of algorithm implementation can be accurately evaluated once the system integration and the algorithm evaluation tests are carried out.
A successful DIAMOND project will have a strong impact on the European SOFC CHP business, technology and science.

List of Websites:

Reported by

HyGear B.V.