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

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.

Section: Test Casementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Hamidi

Ahmadian

Patil

et al. 2019

“…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%

“…They are implemented for the same mission in other works. [7][8][9][10][11] It is proven that effective tuning of heuristic algorithms can serve the purpose of offering fast response protection. 12 In Alipour et al, 2 group search optimization algorithm is improved to meet the coordination problem.…”

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.

“…The relay coordination problem is reformulated as an equivalent quadratically constrained quadratic programming problem in Papaspiliotopoulos et al Using this formulation, the complexity of the problem is significantly reduced. In El‐Fergany and Hasanien, a stochastic fractal search algorithm is used to solve the optimal relay coordination problem of meshed power networks. In this paper, the tripping characteristic of each relay is considered as a decision variables in the optimization problem.…”

Section: Introductionmentioning

confidence: 99%

Parameter uncertainty in the optimal coordination of overcurrent relays

Noghabi

Sadeh

Mashhadi

2018

Summary Generally, the relay coordination problem is solved without considering parameter uncertainties, while uncertainties in the line parameters and current transformer ratios make the fault current passing through the overcurrent relay inaccurate and could cause the miscoordination. To overcome this drawback, in this paper, a novel method based on interval analysis is introduced to model parameter uncertainties in the coordination problem. Considering parameter uncertainties, the coordination constraints are formulated as a set of inequalities with interval coefficients. Monte Carlo simulation technique is used to determine the boundary values of these interval coefficients. In this case, the optimal coordination problem is formulated as an interval linear programming problem. Using mathematical theorems, the optimal value of interval linear programming problem can be obtained by solving a standard linear programming problem. The proposed method is applied to the 8‐bus and Institute of Electrical and Electronics Engineers 30‐bus test systems, and the results show the ability of interval method to model the parametric uncertainties.