Optimal directional digital overcurrent relays coordination and arc-flash hazard assessments in meshed networks

Summary This paper presents a novel application of the stochastic fractal search algorithm to solve the optimal relay coordination problem of meshed power networks. The optimization problem has 3 design variables, which are the time dial, the pickup current, and the tripping characteristic of each relay and subjects to set of coordination constraints. The objective function is adapted to minimize the total operating time of the primary and backup relays while maintaining the validity of coordination within acceptable limits. Three interconnected power systems with various topologies and fault scenarios are demonstrated. Among these 3 test cases, it is worthy emphasizing that the third power system is highly penetrated with 6 distributed generators, which tangle the optimization problems with numerous relay pair scenarios. The validity and the effectiveness of the proposed method are confirmed using the simulation results, in addition to necessary subsequent comparisons to other competing approaches. The simulated numerical results and the performance measures indicate that the stochastic fractal search algorithm is viable and able to generate competitive optimal settings for overcurrent relays and lie in an acceptable elapsed time.

Section: Simulation Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimized settings of directional overcurrent relays in meshed power networks using stochastic fractal search algorithm

El‐Fergany

Hasanien

2017

“…The detailed specifications of the system are available in Chabanloo et al 29 Both ends of feeders are equipped with OCRs, and directional relays as the topology can be changed, and consequently, the direction of power flows will change. OCRs 2,5,10,12,14,17,20,23,25,and 27 are blocked by the directional relays, and they are not considered in protection coordination. Table 13 provides the maximum load and fault currents.…”

Section: Test Casementioning

confidence: 99%

“…In Atteya et al, 23 the application of the modified particle swarm optimization (MPSO) algorithm in an adaptive protection scheme, considering the integration of DGs, is proposed. In El-Fergany, 27 a new objective function is introduced to decrease the arc-flash hazards as well as to retain the optimal coordination of directional OCRs. This method is applicable only to single-stage TCCs, and transient overcurrents are not considered.…”

Section: Introductionmentioning

confidence: 99%

Optimal time‐current graded coordination of multistage inverse‐time overcurrent relays in distribution networks

Hamidi

Ahmadian

Patil

et al. 2019

Summary This paper proposes a method for optimal coordination of multistage overcurrent relays (OCRs) in radial distribution networks, including industrial, rural, and urban grids. The proposed method optimally coordinates multistage time‐current curves (TCCs) using the genetic algorithm (GA). The proposed method is able to determine the proper TCC type (eg, moderately inverse, very inverse, and extremely inverse), pickup current, and time‐setting multiplier (TSM) for each stage of TCCs. The proposed method utilizes the dynamic models of OCRs and fuses. This safeguards the relays against the maloperations resulting from the DC decaying part of fault currents and transient overcurrents caused by transformer energization or motor starting. The proposed method is evaluated using DIgSILENT Power Factory for power system analysis and Matlab for implementation of the proposed method. According to the simulation outcomes, the advantages and disadvantages of the proposed method are discussed and compared with the existing methods.

“…Heuristic algorithms are relatively quick and good candidates to determine optimal/near‐optimal solutions. They are implemented for the same mission in other works . It is proven that effective tuning of heuristic algorithms can serve the purpose of offering fast response protection .…”

Section: Introductionmentioning

confidence: 99%

Coordination of mixed distance and directional overcurrent relays: Miscoordination elimination by utilizing dual characteristics for DOCRs

Yazdaninejadi

Nazarpour

Talavat

2018

Summary Keeping selectivity among protective devices in electrical grids is of crucial importance. This task in the combinatorial protection scheme of distance and directional overcurrent relays (DOCRs) stands as a complicated problem, especially in interconnected networks. To overcome this issue, this paper proposes an enhanced protection coordination (PC) scheme by employing dual time‐current characteristics (D‐TCCs) for overcurrent relays which are followed by two inverse‐time curves in series. These characteristics simplify the complexity of the problem and yield higher flexibility and extensibility in PC process which helps to meet selectivity requirements. However, these characteristics can be implemented by numerical DOCRs which poses investment costs. Therefore, a techno‐economic optimal replacement model is devised to attain a least‐cost numerical DOCRs deployment plan while eliminating miscoordination and minimizing total operation time of the relays. Furthermore, inverse‐time curves of DOCRs are selected optimally among available options for conventional relays. By doing so, the attained flexibility is intensified which lessens imparted economic burden through alleviating the replacement level of numerical DOCRs. The proposed approach calls the need for making amendments in coordination points to handle coordination problem in the case where both conventional DOCRs and numerical DOCRs with D‐TCCs are present. Therefore, coupled with the conventional selectivity constraints, the constraint associated with new coordination points are all together accommodated in the optimization process. The proposed model demonstrates a mixed integer nonlinear programming fashion which is solved with sine‐cosine algorithm. Several numerical studies are carried out to interrogate the validity of the proposed approach. The obtained results are encouraging.