Appropriate Accuracy of Models for Decision-Support Systems: Case Example for the Elbe River Basin

Given the growing complexity of water-resources management there will be an increasing need\ud for integrated tools to support policy analysis, communication, and research. A key aspect of the design is the\ud combination of process models from different scientific disciplines in an integrated system. In general these\ud models differ in sensitivity and accuracy, while non-linear and qualitative models can be present. The current\ud practice is that the preferences of the designers of a decision-support system, and practical considerations\ud such as data availability guide the selection of models and data. Due to a lack of clear scientific guidelines the\ud design becomes an ad-hoc process, depending on the case study at hand, while selected models can be overly\ud complex or too coarse for their purpose. Ideally, the design should allow for the ranking of selected\ud management measures according to the objectives set by end users, without being more complex than\ud necessary. De Kok and Wind [2003] refer to this approach as appropriate modeling. A good case example is\ud the ongoing pilot project aiming at the design of a decision-support system for the Elbe river basin. Four\ud functions are accounted for: navigability, floodplain ecology, flooding safety, and water quality. This paper\ud concerns the response of floodplain biotope types to river engineering works and changes in the flooding\ud frequency of the floodplains. The HBV-D conceptual rainfall-runoff model is used to simulate the impact of\ud climate and land use change on the discharge statistics. The question was raised how well this rainfall-runoff\ud model should be calibrated as compared to the observed discharge data. Sensitivity analyses indicate that a\ud value of R2 = 0.87 should be sufficient

A Structured Approach for Design of an SST Control Architecture Based on CAFCR Framework

Solid-State Transformers (SSTs) are a promising alternative to conventional oil-cooled copper-and-iron based power transformers in the electricity grid. They offer opportunities to make secondary (MV/LV) substations flexible, intelligent and modular. This work proposes to use a generic design tool from Systems Engineering - the CAFCR framework - for the SST control system to unlock its full potential. The framework provides a structured and thorough approach for collaboration and design, connecting what is desired with what is possible. The advantages are as follows: 1) Many research on SSTs has already been done and the framework can help to collect and aggregate the performed research; 2) It also helps to ensure important aspects are not overlooked and designs meet the necessary requirements; 3) Furthermore, it can identify new areas of research and facilitate new ideas. In the paper, we apply the CAFCR framework to SST by starting with the perspective of the Distribution System Operator (DSO) as the customer and an exploration of the application surroundings (substation housing, grid embedding). We then continue to examine the functionalities that are required and desired for an SST from a black-box perspective. These functionalities are presented in a table where the functionalities are divided into a) ‘additional features’ vs ‘mimicking a regular transformer’, and b) ‘normal operation’ vs. ‘fault conditions’. Based on this, four areas of research have been indicated to obtain a flexible, future-proof control architecture. To see how these areas could work together, a task division is proposed as well as applying distributed control to the MV side

A Structured Approach for Design of an SST Control Architecture Based on CAFCR Framework

Solid-State Transformers (SSTs) are a promising alternative to conventional oil-cooled copper-and-iron based power transformers in the electricity grid. They offer opportunities to make secondary (MV/LV) substations flexible, intelligent and modular. This work proposes to use a generic design tool from Systems Engineering - the CAFCR framework - for the SST control system to unlock its full potential. The framework provides a structured and thorough approach for collaboration and design, connecting what is desired with what is possible. The advantages are as follows: 1) Many research on SSTs has already been done and the framework can help to collect and aggregate the performed research; 2) It also helps to ensure important aspects are not overlooked and designs meet the necessary requirements; 3) Furthermore, it can identify new areas of research and facilitate new ideas. In the paper, we apply the CAFCR framework to SST by starting with the perspective of the Distribution System Operator (DSO) as the customer and an exploration of the application surroundings (substation housing, grid embedding). We then continue to examine the functionalities that are required and desired for an SST from a black-box perspective. These functionalities are presented in a table where the functionalities are divided into a) ‘additional features’ vs ‘mimicking a regular transformer’, and b) ‘normal operation’ vs. ‘fault conditions’. Based on this, four areas of research have been indicated to obtain a flexible, future-proof control architecture. To see how these areas could work together, a task division is proposed as well as applying distributed control to the MV side