An approach for generating grid equivalents for different use cases

Modern technological trends for massive RES integration into the electrical grid, together with the evolution of energy storage systems and the increasing penetration of electric vehicles contribute greatly to decarbonization of the energy systems and energy efficiency improvement. This initiates, however, significant challenges for the future operation of the EU electricity system, characterized by the wide diversity of electrical networks among EU members.

Ideally, all system operators should have full models of all grids to carry out the network analysis in a digital simulation environment. However, at the present time, no network operator has models of the entire physical grid, in particular covering different voltage levels and all neighbouring network operators. The detailed modelling of the whole power system requires a huge input data and complex structure, and this clearly contributes to the problem. Therefore, grid equivalents adequately representing all parts of the European electricity systems are needed.

“Grid equivalenting” will be used, which is defined as the process to generate a grid equivalent model encompassing a large part of a network substituted by a smaller counterpart having the same relevant properties. To this aim, the network models of use cases will be designed in numerical power system simulation environment.

Then, a clustering methodology for transmission and distribution systems up to the end-user level will be applied, and a detailed approach for generating grid equivalents will be used for different use cases. To realise the transition from feeder to the network level, new grid elements have to be considered, for example transformers, generators or synchronous machines. Depending on the available data, variables dealing with these grid elements are to be examined to complete the grid representation.

During the equivalenting process, a large, branched part of the network can be substituted by a relevant simplified counterpart while keeping network characteristics at an appropriate level of accuracy. This will reduce the large amount of calculations and increase the model simulation speed greatly. Generating grid equivalents instead of the detailed model has thereby a great practical significance and the grid equivalents can be convenient for different power system applications.

In deliverable D4.2, a general concept of generating grid equivalents is introduced alongside a classification of the generated grid equivalents. The proposed methodology is needed to generate grid equivalents that will allow an accurate analysis of the complex network, by considering local active elements in the grid. Based on the developed INTERPLAN use cases, showcases and requirements for network models and interfaces, the project will provide and deliver grid equivalents covering all voltage levels to be incorporated in the integrated operation planning tool and semi dynamic simulations environment.

In a further step, the developed grid equivalents will be validated during the project runtime. Hence, a validated set of grid equivalents will be provided publicly and presented to the scientific community during international conferences and through relevant publications. Using appropriate grid equivalents for the distribution grid, the complexity of such investigations can be reduced significantly and can help distribution system operators (DSOs) to identify the optimal standard parametrization of small-scale distributed energy resources (DER).

The consortium intends to provide an integrated operation planning tool to the prospective users (mainly transmission system operators (TSOs) and DSOs)) with the following features and advantages:

  • It will include a library of grid equivalents responding to all known needs of operators and system analysts and covering all voltage levels and their active components
  • It will provide easy-to-use grid clustering techniques that are adaptive and responsive to the dynamic growth of the evolving grid, thus refreshing and valid as new technologies emerge.
An approach for generating grid equivalents for different use cases
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