M. Faghihi Rezaei; M. Gandomkar; J. Nikoukar
Abstract
Installing the renewable energy sources (RESs) in distribution networks changes the fault current direction, increases the fault current level and, consequently, eliminates the protection coordination between the protective devices. Overcurrent relays are among the most important protective devices in ...
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Installing the renewable energy sources (RESs) in distribution networks changes the fault current direction, increases the fault current level and, consequently, eliminates the protection coordination between the protective devices. Overcurrent relays are among the most important protective devices in distribution networks. Proper performance of the protective system requires protection coordination between the overcurrent relays. The present paper proposes a new protection coordination scheme using digital directional overcurrent relays (DOCRs) and dual-setting digital overcurrent relays (DS-DOCRs) in the distribution network in the presence of the RESs and energy storage systems (ESSs). For this purpose, a multi-stage objective function was used. In the first stage, a weighted objective function was employed to optimize the size and location of the RESs as well as the location and impedance of the FCLs in order to reduce the loss, improve the voltage profile and decrease the variation of the feeders' currents at the connection time of the RESs. In the second stage, DOCR and DS-DOCR settings optimization, which included parameters A and B in addition to parameters I${}_{p}$ and TDS, was used to restore the lost protection coordination for the fault current in the shortest possible time. The simulation results on the IEEE 33-bus network in the presence of RESs using genetic algorithm and PSO algorithm method as well as DPL programming language in DIgSILENT software showed that the total operating time of digital relays and network loss were reduced and voltage profile was significantly improved.
H. Shad; M. Gandomkar; J. Nikoukar
Abstract
To assure the security and optimal protection coordination in meshed distribution networks, clearing faults swiftly and selectively is an essential priority. This priority, when hosting distributed generations (DGs), becomes the main challenge in order to avoid the unintentional DGs tripping. To overcome ...
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To assure the security and optimal protection coordination in meshed distribution networks, clearing faults swiftly and selectively is an essential priority. This priority, when hosting distributed generations (DGs), becomes the main challenge in order to avoid the unintentional DGs tripping. To overcome the mentioned challenge, this paper establishes a truth table to select new settings of directional overcurrent relays (DOCRs) characteristics which can be defined by users. It concentrates on minimizing the overall relays operating time. Typically, the conventional coordination between pair relays is achieved by two settings: time dial setting (TDS) and pickup current (Ip). Besides these adjustments, the suggested approach, considered the two coefficient constant of the inverse-time characteristics, namely the relay characteristics (A) and the inverse-time type (B), as continuous to optimize. Thus, more flexibility is attained in adjusting relays features. In addition, the inclusion of user-defined settings on numerical DOCRs, not only decreases the overall operating time of relays, but also improves the performance of the backup relays against the fault points. This approach illustrates a constrained non-linear programming model tackled by the combined particle swarm optimization (PSO) and whale optimization algorithm (WOA). The efficiency of the suggested approach is assessed though the IEEE 8-bus and the distribution portion of IEEE 30-bus system with synchronous-based DG units. The obtained results demonstrate the performance of approach and will be discussed in depth.
S. Ghobadpour; M. Gandomkar; J. Nikoukar
Abstract
Power quality, reliability, loss reduction, and fault clearing times are essential factors in distribution networks. Radial distribution networks often face two problems, line losses and voltage drop at the end of the grid. Connecting distributed generation (DG) can resolve these problems, but it can ...
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Power quality, reliability, loss reduction, and fault clearing times are essential factors in distribution networks. Radial distribution networks often face two problems, line losses and voltage drop at the end of the grid. Connecting distributed generation (DG) can resolve these problems, but it can also cause miscoordination. Protection coordination in the presence of DGs is a major challenge of radial networks. Herein, the optimal location and size of DGs in a radial distribution network protected by fuse and recloser were determined to modify bus voltage profile and reduce active-reactive lines' losses. Since the protection coordinate was eliminated by connecting DGs to the network, by using the SFCL in the output of DGs and minimizing its size, it attempted to restore the protection coordination between the fuse and the recloser. In this method, a nonlinear multi-objective function was introduced to be optimized by genetic and PSO algorithms. The simulation was performed in DIgSILENT software. The effectiveness of the proposed method was verified via IEEE 33-bus test systems.
