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چکیده
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The proliferation of distributed energy resources (DERs), advancement of power electronic converter technologies, and integration of microgrids with an active distribution system have increased the necessity of monitoring the distribution system for various purposes such as energy management, real-time market operation, and allocation of dynamic price for the real-time market. However, monitoring the distribution system is difficult due to its unbalanced nature, limited number of measurements, and many nodes. But, the advancement in information and communication technologies (ICTs), such as advanced metering infrastructures and synchro-phasors, has made the distribution system more observable and therefore relatively convenient for state estimation. Still, distribution system state estimation (DSSE) is mathematically intensive and requires a substantial computational resource. The estimation problem, formulated as a non-linear mathematical program, adds the computational burden for the large-scale optimization problem. To address this challenge, this study proposes a distributed optimization method to solve the DSSE problem. Furthermore, AC-DC system integration with the power electronic converters in the distribution systems is increasing with the inclusion of renewable energy sources at the distribution level. Therefore, a combined state estimation technique with an AC-DC system is necessary. In this paper, simplified power electronics converter models are developed for AC-DC DSSE. The sequential linear state estimation for the AC-DC distribution system is developed to overcome the mathematical complexity caused by the non-linear formulation. Thus, Bender's decomposition-based state estimation technique is proposed. The proposed DSSE algorithm's accuracy, robustness, and scalability is tested for modified IEEE 13-node and IEEE 123-node unbalanced multi-phase AC-DC distribution system for radial and meshed system.
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