Showing 3 results for Graph Theory
H. Moayedirad, H. Falaghi , M. Farshad ,
Volume 11, Issue 1 (4-2014)
Abstract
One of the ways of reducing active power losses in the distribution networks is using the network reconfiguration for different load levels. Since the number of possible configuration of a distribution network is usually very much and then review of all of them (especially in the network of large-scale) to finding the optimal configuration is not possible simply, therefore in this paper a new algorithm based on the graph theory and the its developed algorithms are presented for the reconfiguration of distribution networks. The proposed algorithm start with a meshed distribution system which obtains by considering all switches closed. The distribution system models as a super graph and proportionate weights to losses are attributed to each branch of this graph. Due to the nature of reconfiguration operations, the most important factor in the distribution networks is to reach the optimal configuration in the shortest possible time. The developed algorithms of graph theory have appropriate speed and considering that the number of load flow calculation in the proposed algorithm is little as compared to other methods. Therefore the proposed algorithm of this paper, as compared to other methods has good speed in reaching the desired optimum. The proposed algorithm has been implemented on the sample distribution networks. The obtained results show superiority and efficiency of proposed algorithm as compared to with other methods.
Mr. Hossein Nosratpoor, Dr. Ali Zanganeh,
Volume 16, Issue 1 (5-2019)
Abstract
In this paper, a self-healing approach for smart distribution network is presented based on Graph theory and cut sets. In the proposed Graph theory based approach, the upstream grid and all the existing microgrids are modeled as a common node after fault occurrence. Thereafter, the maneuvering lines which are in the cut sets are selected as the recovery path for alternatives networks by making cut sets of the faulted line. After forming the candidate networks with the minimum number of switching, an unbalanced three phase power flow is performed to be assured that the new network configuration does not violate technical constraints. In the case of the constraints violation, the other candidate networks with the same number of switching or more are assessed to find a proper scheme with high loadability and low voltage unbalance values. The proposed approach is scrutinized in two different case studies: with and without microgirds connection to the distribution network. The simulation results applied on a typical distribution network in the MATLAB software show the valuable performance of the proposed approach. The using of the Graph theory has reduced the number of switching and excitation time in comparison with evolutionary search approaches.
Hamed Shahmoradi, Dr. Aref Doroudi, Mohammadsaleh Farrokhi,
Volume 21, Issue 4 (12-2024)
Abstract
Power system stability, control, and design studies are time-consuming due to the formation of large size and heavy interconnection networks. Reduced ordered dynamic equivalent methods are thus so desirable for performing these studies. Simple equivalents are obtained by converting large and complex networks into smaller networks. One of the approaches to the problem of model reduction is to find coherency-based generator grouping and aggregation. In this method, first, based on network characteristics, each group of coherent generators is replaced with a dynamic equivalent, and then the dynamic equivalent of the generators is used in the studies of power networks. In this regard, in this article, using graph theory and clustering quality index, a novel method for finding coherent generators in a power network is presented. The proposed method is simple and the network admittance matrix is the only information required by this approach. The IEEE 39-bus network is used to show the effectiveness of the proposed approach. The comparison of the results with other research shows that the proposed method identifies the coherent generators with an acceptable approximation.
