The necessary parameters for a new, improved cell model are calculated in MATLAB. An appropriate solution method is used to gradually reduce the network of each cell, starting with those cells that have the lowest number of tie lines connected to other cells. According to this scheme a nodal admittance matrix is set up for each cell. The border system includes those nodes that connect the internal system with die external system. In the partitioning process the nodes are assigned to an external, an internal and a border system. The overall network, which needs to be divided into cells before a reduction method can be tested, is then partitioned in a system of nodes in order to enable a systematic approach for network reduction. In order to derive a cell model, presently used network reduction methods were reviewed for their applicability. Both matrices contain information about the topology of the network. The coefficients are formed by the corresponding elements in the two-port matrix. These matrix elements represent the coefficients of the nodal voltages within the nodal equations. If this system of equations is represented in matrix notation, the nodal admittance matrix is obtained. A description of the not yet reduced overall network is achieved by setting up the nodal equations for each node within the network. In order to facilitate an improvement in accuracy, the electrical lines have to be modelled correctly, which means each line needs to be represented by a 2x2 matrix according to four-pole-theory. The purpose is to improve the previous cell model regarding its accuracy of power flows. Since an existing grid of the 5 kV medium voltage level has already been fully modelled in the NEPLAN software program, a small partial network was taken for testing the applicability of different network simplification and reduction methods using an algorithm programmed in MATLAB. Since the greatest challenge for implementation of such changes is represented by the electrical grid in comparison with heat grids or gas networks, there have been various projects at the Chair of Energieverbundtechnik to enable a corresponding modelling of the electrical grids using a cellular approach in order to create future, efficient hybrid networks. The extensive alterations within the structure of energy producers and consumers as well as the binding fulfilment of various energy policy objectives require changes in today’s energy systems and new methods for network planning and operational control.
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