Dial Setting Research Articles

Adaptive CWT‐based overcurrent protection for smart distribution grids considering CT saturation and high‐impedance fault

In this study, an adaptive continuous wavelet transform (CWT)-based overcurrent protection for smart grids is proposed to enhance the overcurrent protection performance encountering high-impedance fault (HIF) and current transformer (CT) saturation, which are extremely complex phenomena and their impacts often cause mis-coordination or mal-operation. The proposed algorithm samples three phase current waveforms and imports them to CWT to extract high frequency coefficients. Afterwards, the sum of absolute values of the coefficients, S coef , is calculated for each sample during the last cycle. Meanwhile, several simulations related to HIFs with different impedances and CT saturations with different severities are executed and the fault currents and the sum of absolute values of the coefficients are achieved and saved in the relay memory as ( X , Y ) coordinates of points ( I L-fault , S L-coef ), named `learning data'. Thereafter, each S coef is imported to the X - Y plane and, consequently, the occurrence of HIF or CT saturation is detected and the real-fault current is estimated by both non-linear interpolation and extreme learning machine approaches. Subsequently, new time dial setting and I pickup of the relays are computed and reloaded. Security, dependability, and sensitivity of the proposed adaptive protection method are confirmed by numerous simulation studies.

Gravitational Search Based Algorithm for Optimal Coordination of Directional Overcurrent Relays Using User Defined Characteristic

Due to dependency on Plug Setting (PS), Time Dial Setting (TDS), size of the network, more than one back-up relays for one primary relay and other technical constraints, coordination of Directional Overcurrent Relays (DOCRs) is an extremely constrained and nonlinear optimization problem. In this paper, a new Gravitational Search (GS) based algorithm is presented for achieving optimal coordination of directional overcurrent relays. The proposed algorithm utilizes user defined characteristic for inverse time overcurrent relays than the predefined standard curves. The user defined relay characteristic deals with constants that control the shape of the characteristics as variable adjustable values which are optimally chosen along with TDS and Plug Setting Multiplier (PSM). The performance of the proposed algorithm has been evaluated on 8-bus, 15-bus and IEEE 30-bus distribution network at different fault locations (near-end, far-end and middle point). In addition, the time of operation of some of the primary relays at different fault locations on IEEE 30-bus distribution network is also presented. At the end, comparative evaluation of the proposed algorithm with other optimization algorithms having different relay characteristics presented in the literature clearly indicates its effectiveness and superiority in terms of the sum of total primary relays operating time.

Coordination Improvement of Directional Overcurrent Relays in a Microgrid Using Modified Particle Swarm Optimization Algorithm

An accurate and fast relaying scheme is of high importance in a radial distribution network and it becomes complex to realize in a multi-sourced distribution network with Distribution Generators (DGs). The study of the existing relay coordination of the 33 kV Idu Industrial Park Distribution Network, Abuja and its improvement opportunities is presented in this research in other to guarantee safety of operation and protection of the distribution network against the effects of faults. A proposed 6 Bus Idu microgrid based on planned network expansion program was modeled using DIgSILENT PowerFactory software. Load Flow and Fault Analyses were performed on the modeled network to determine appropriate Directional Overcurrent Relay (DOCR) settings and a Modified Particle Swarm Optimization Algorithm (MPSO) in MATLAB environment was used to optimize the Time Dial (TD) and Pickup (PU) settings of the DOCRs. The modification adopted was to keep the solution space within boundaries so as to achieve fast convergence. The sum of the operating time of the radial feeder was found to be 3.68 s while that of the proposed 6 Bus Microgrid with 14 DOCRs and 3 DGs was found to be 3.7903s which was quite fast and satisfactory after validation on the modeled microgrid.

Hybridized Symbiotic Organism Search Algorithm for the Optimal Operation of Directional Overcurrent Relays

This paper presents the solution of directional overcurrent relay (DOCR) problems using Simulated Annealing based Symbiotic Organism Search (SASOS). The objective function of the problem is to minimize the sum of the operating times of all primary relays. The DOCR problem is nonlinear and highly constrained with two types of decision variables, namely, the time dial settings (TDS) and plug setting (PS). In this paper, three models of the problem are considered, the IEEE 3-bus, 4-bus, and 6-bus, respectively. We have applied SASOS to solve the problem and the obtained results are compared with other algorithms available in the literature.

LUT Assisted Adaptive Overcurrent Protection of Reconfigurable Microgrids

Microgrids are the key solution to handle the growing technical, environmental and economical concerns of existing power system networks. The purpose of this paper is to develop an intelligent and adaptive overcurrent protection system for a microgrid. This system is capable of monitoring, protecting and controlling the microgrid. A look up table is created and maintained at the central protection system of the microgrid, which has details of normal and faulted current in all feeders for various topologies of the microgrid system. It has the optimized values for time dial setting and operating time of relays for faults at a specific location in the reconfigured system, which is generated using Dual Simplex algorithm. Hence the Central Protection System aids in providing suitable overcurrent relay coordination to the microgrid, which may incur reduced network disconnection. The hardware prototype of the Central Protection System is realized, tested and validated on a balanced 21-bus microgrid system.

Improved Solutions for the Optimal Coordination of DOCRs Using Firefly Algorithm

Nature‐inspired optimization techniques are useful tools in electrical engineering problems to minimize or maximize an objective function. In this paper, we use the firefly algorithm to improve the optimal solution for the problem of directional overcurrent relays (DOCRs). It is a complex and highly nonlinear constrained optimization problem. In this problem, we have two types of design variables, which are variables for plug settings (PSs) and the time dial settings (TDSs) for each relay in the circuit. The objective function is to minimize the total operating time of all the basic relays to avoid unnecessary delays. We have considered four models in this paper which are IEEE (3‐bus, 4‐bus, 6‐bus, and 8‐bus) models. From the numerical results, it is obvious that the firefly algorithm with certain parameter settings performs better than the other state‐of‐the‐art algorithms.

Coordination of directional over‐current relays in active distribution networks using generalised benders decomposition

Coordination of directional over-current relays (DOCRs) as the primary protection of meshed distribution networks is formulated as a mixed-integer non-linear programming (MINLP) problem. The coordination of DOCRs has been mainly accomplished using heuristic methods. Therefore, this study aims at proposing an efficient analytical tool for this problem. A two-stage analytical approach based on the generalised Benders decomposition is proposed to find the time and current settings of DOCRs with minimum operating time, while satisfying coordination constraints. The standard curves and the discrete current settings of DOCRs are determined in the first stage using a relaxed MINLP master problem. The obtained settings are then passed to the second stage to determine the time dial settings. In this stage, two linear sub-problems are solved to check feasibility and optimality of the solution. In each sub-problem another linear optimisation problem is developed to construct new constraints that are then backed to the first stage to remove the infeasibility and reduce the optimality gap, respectively. The iterative process continues till all the infeasibilities are removed and the optimality gap decreases below a given threshold. The obtained results on test cases are compared with two well-known MINLP solvers and some previous approaches.

Sevoflurane sparing effect of dexmedetomidine in patients undergoing laparoscopic cholecystectomy: A randomized controlled trial.

Background and Aims:Sevoflurane is an excellent but expensive anesthetic agent for laparoscopic cholecystectomy. To decrease sevoflurane consumption during surgery adjuvants like dexmedetomidine may be used. Dexmedetomidine is a recently introduced drug which alleviates the stress response of surgery, produces sedation and analgesia. We aimed to evaluate sevoflurane sparing effect of dexmedetomidine in patients undergoing laparoscopic cholecystectomy under entropy-guided general anesthesia (GA).Material and Methods:In this prospective randomized control study, 100 American Society of Anesthesiologists physical status I–II adult surgical patients scheduled to undergo laparoscopic cholecystectomy were enrolled. Patients were randomly divided into two groups (n = 50). In dexmedetomidine group, patients received intravenous (IV) dexmedetomidine 0.5 μg/kg over 10 min before induction followed by 0.5 μg/kg/h infusion while in control group, patients received the same volume of normal saline.Results:Sevoflurane consumption was 41% lower in dexmedetomidine group as compared to control group (7.1 [1.6] vs. 12.1 [1.9] ml, P <0.001). A 40% reduction was observed in induction dose of propofol (83.0 [19.1] vs. 127.6 [24.8] mg, P <0.001). Mean Riker sedation-agitation score, visual analog score for pain and Aldrete's score were significantly lower in dexmedetomidine group as compared to control group. None of the patients experienced any significant side effects.Conclusion:A 41% reduction in sevoflurane consumption was observed in patients receiving IV dexmedetomidine as an adjuvant in patients undergoing laparoscopic cholecystectomy under GA.

A prospective randomized study comparing recovery following anesthesia with a combination of intravenous dexmedetomidine and desflurane or sevoflurane in spinal surgeries.

Background and Aims:Desflurane and sevoflurane are inhalational anesthetics which provide stable intraoperative hemodynamics and rapid emergence from anesthesia. Dexmedetomidine is an α2-agonist with sedative and hypnotic effects. We compared recovery following anesthesia with a combination of a continuous intravenous infusion of dexmedetomidine and desflurane or sevoflurane in cases of spine surgeries because no such data are available from India.Material and Methods:It was a single-blind, prospective, randomized study. After institutional ethics committee approval, patients were randomly allocated to one of the two groups of fifty patients each. Group D received desflurane and Group S received sevoflurane, along with dexmedetomidine 0.5 μg/kg/h IV infusion for maintenance of anesthesia.Results and Conclusions:Extubation time (ET) in Group D was shorter by 4.2 min than in Group S (10.1 ± 2.2 and 14.2 ± 1.3; P = 0.004). Postoperative recovery, postoperative analgesic, and antiemetic requirement between the groups were comparable The mean dial setting required to maintain the minimum alveolar concentration of 1 intraoperatively was 3.1 for desflurane and 0.7 for sevoflurane.

Effect of Intravenous Magnesium Sulfate on the Minimum Alveolar Concentrations of Desflurane Using Bispectral Index Monitoring: A Prospective Randomized Double-blind Controlled Study.

Background:Magnesium sulfate has been implicated to influence the minimum alveolar concentration (MAC) of various volatile anesthetics, but its effect on desflurane remains unanswered so far.Aim:To study the effect of perioperative intravenous magnesium sulfate on MAC of desflurane using bispectral index (BIS) monitoring.Settings:Operating room of a tertiary care hospital.Design:A prospective, randomized, controlled, double-blind clinical trial.Methods:Sixty American Society of Anesthesiologists Physical Status I/II patients aged 18–65 years and scheduled for breast conservative surgeries were randomized into three groups of 20 each. Control group (Group 1) was administered 100 ml normal saline (NS) as bolus followed by NS infusion. Magnesium (Mg) was administered as bolus of 40 mg/kg in 100 ml NS followed by NS infusion in Group 2 and as bolus of 40 mg/kg followed by infusion of 10 mg/kg/h of Mg in NS in Group 3. Anesthesia was induced with propofol, fentanyl, and atracurium. Dial setting of desflurane was adjusted to target a BIS of 45–55. Time from cessation of desflurane to beginning of spontaneous movement, time taken to respond to verbal commands, time of extubation, and time taken to reach BIS value of 70 were recorded.Statistical Analysis:Statistics was done using SPSS program using ANOVA and the Chi-square test for variables and a P < 0.05 was taken to indicate a significant difference.Results:No significant difference was present in MAC, end-tidal desflurane, and cumulative consumption of morphine. Recovery was similar in Group 2 and Group 3, but time to eye opening (P = 0.011), time to respond to verbal commands (P < 0.001), and time to extubate (P < 0.001) were significantly delayed when compared with patients in Group 1. Hemodynamic changes were comparable among three groups.Conclusions:From this study, we conclude that MACs of desflurane using BIS as a guide remains unaffected by perioperative infusion of magnesium sulfate.

Effects of Two Intranasal Dexmedetomidine Doses as Premedication on Sevoflurane EC50 for Successful Laryngeal Mask Airway Placement in Children.

Objective To observe the effects of two different intranasal dexmedetomidine doses as premedication on the EC50 of sevoflurane for successful laryngeal mask airway placement in children. Methods Children aged 3-6 years, of American Society of Anesthesiologists physical status 1, and scheduled for plastic surgery were enrolled in this study. Children were assigned to receive either spray administration of intranasal dexmedetomidine 1 μg/kg (group D1, n=21) or 2 μg/kg (group D2, n=20) approximately 30 minutes before anesthesia. Anesthesia was induced with sevoflurane up to 8% in 100% O2, with fresh gas flow set to 6 L/min. After the pupil fixed to the middle position, sevoflurane dial setting was reduced to 5% and fresh gas flow reduced to 3 L/min. The endtidal sevofluran (ETsevo) concentration for laryngeal mask airway insertion sustained for 10 minutes after vein intubation, which was determined according to the Dixon's up and down method. The initial endtidal sevoflurane concentration in each group was set at 2%. ETsevo was increased/decreased (1:1.2) in the next patient according to the response to laryngeal mask airway insertion. Bispectral index, mask acceptance, all response to laryngeal mask airway insertion, and ETsevo of laryngeal mask airway insertion of children were recorded. Results The bispectral index value was 77.4±3.6 in group D2, which was significantly lower than that (87.4±1.9) in group D1 when children entered operation room (P<0.05). Mask acceptance was 76.2% in group D1 and 90.0% in group D2. The EC50 of sevoflurane for laryngeal mask airway insertion was 1.09% (95% CI=0.89%-1.28%) in group D2, which was lower than 1.59% (95% CI=1.41%-1.78%) in group D1 (P<0.05). Conclusion Compared with the dose of 1 μg/kg, spray administration of intranasal dexmedetomidine 2 μg/kg as premedication can reduce the sevoflurane EC50 for successful laryngeal mask airway placement in children.

Behavior of induction disc overcurrent relays as a function of the frequency

This article analyzes the behavior of induction disc overcurrent relays as a function of the frequency. A model for the simulation of the electromechanical device is shown, and this model is verified by experimental measurements. Experimental results were obtained for three overcurrent relays from different manufacturers, by varying the magnitude of injected current and the time dial setting (for wide ranges of frequencies, which were selected for the tests). Experimental results are in concordance with the developed model, and the average percentage errors are in the order of 2%. The braking effect due to the magnetic fluxes created by the operative current can easily be included (or not) in the model, and it is shown that the inclusion of this effect: (a) improves the accuracy of the model, for tests in the linear zone of the ferromagnetic core; (b) can be useful to obtain accurate results for the non-linear zone of the ferromagnetic core, although the model was developed by assuming linearity of the ferromagnetic core. On the other hand, some inaccuracy could be expected for the time dial setting because this adjustment is performed by a continuous movement in a calibrated knob; this fact can easily be included in the model, in order to improve the accuracy of results of simulations.

Accuracy, reproducibility, and uncertainty analysis of thyroid‐probe‐based activity measurements for determination of dose calibrator settings

In the nuclear medicine department, the activity of radiopharmaceuticals is measured using dose calibrators (DCs) prior to patient injection. The DC consists of an ionization chamber that measures current generated by ionizing radiation (emitted from the radiotracer). In order to obtain an activity reading, the current is converted into units of activity by applying an appropriate calibration factor (also referred to as DC dial setting). Accurate determination of DC dial settings is crucial to ensure that patients receive the appropriate dose in diagnostic scans or radionuclide therapies. The goals of this study were (1) to describe a practical method to experimentally determine dose calibrator settings using a thyroid-probe (TP) and (2) to investigate the accuracy, reproducibility, and uncertainties of the method. As an illustration, the TP method was applied to determine 188Re dial settings for two dose calibrator models: Atomlab 100plus and Capintec CRC-55tR. Using the TP to determine dose calibrator settings involved three measurements. First, the energy-dependent efficiency of the TP was determined from energy spectra measurements of two calibration sources (152Eu and 22Na). Second, the gamma emissions from the investigated isotope (188Re) were measured using the TP and its activity was determined using γ-ray spectroscopy methods. Ambient background, scatter, and source-geometry corrections were applied during the efficiency and activity determination steps. Third, the TP-based 188Re activity was used to determine the dose calibrator settings following the calibration curve method [B. E. Zimmerman et al., J. Nucl. Med. 40, 1508-1516 (1999)]. The interobserver reproducibility of TP measurements was determined by the coefficient of variation (COV) and uncertainties associated to each step of the measuring process were estimated. The accuracy of activity measurements using the proposed method was evaluated by comparing the TP activity estimates of 99mTc, 188Re, 131I, and 57Co samples to high purity Ge (HPGe) γ-ray spectroscopy measurements. The experimental 188Re dial settings determined with the TP were 76.5 ± 4.8 and 646 ± 43 for Atomlab 100plus and Capintec CRC-55tR, respectively. In the case of Atomlab 100plus, the TP-based dial settings improved the accuracy of 188Re activity measurements (confirmed by HPGe measurements) as compared to manufacturer-recommended settings. For Capintec CRC-55tR, the TP-based settings were in agreement with previous results [B. E. Zimmerman et al., J. Nucl. Med. 40, 1508-1516 (1999)] which demonstrated that manufacturer-recommended settings overestimate 188Re activity by more than 20%. The largest source of uncertainty in the experimentally determined dial settings was due to the application of a geometry correction factor, followed by the uncertainty of the scatter-corrected photopeak counts and the uncertainty of the TP efficiency calibration experiment. When using the most intense photopeak of the sample's emissions, the TP method yielded accurate (within 5% errors) and reproducible (COV = 2%) measurements of sample's activity. The relative uncertainties associated with such measurements ranged from 6% to 8% (expanded uncertainty at 95% confidence interval, k = 2). Accurate determination/verification of dose calibrator dial settings can be performed using a thyroid-probe in the nuclear medicine department.

Dual-setting directional over-current relays: An optimal coordination in multiple source meshed distribution networks

To guarantee a safe operating scheme against the probable faults, an accurate and fast relaying scheme is of high priority. This challenge seems to be more sophisticated in multiple source meshed distribution networks hosting distributed generations (DGs). In this case, the current experiences bidirectional flows. More recently, dual-setting over-current relays are evolved as competent countermeasures for such cases. In this way, establishing an optimal coordination strategy is recognized as the first prerequisite in assuring a safe protection scheme. To this end, the present study aims at minimizing the overall operating time of primary and backup relays. Typically, the coordination problem is carried out by adjusting two parameters namely, pick up current (Ip) and time dial setting (TDS). In contradiction, the proposed approach follows a user-defined settings supported by some operating rules. Thus, besides the aforementioned settings, the coefficients of the inverse-time characteristics are also optimized. In other words, more flexibility is attained in adjusting relay’s characteristic in regard of the network’s loading and topological changes. Furthermore, inclusion of operating rules in main objectives, not only reduces the sum of operating time of all relays, but also increases the efficiency of backup relays regarding the break points in meshed networks. In other words, the covering zone by each backup relay is increased. The proposed approach demonstrates a non-linear programming fashion which is tackled based on genetic algorithm (GA). Several numerical studies are carried out to interrogate the validity of the proposed approach encountering different fault scenarios. The obtained results are encouraging.

Optimal coordination of directional overcurrent relays in power systems using Symbiotic Organism Search Optimisation technique

The modern power system networks are very complex and often consist of multiloop structures with increased penetration of renewable energy sources-based distributed generations. Directional overcurrent relays (DORs) are the key protection devices in such networks and their coordination has a profound impact on the overall protection of networks. Optimisation of DOR settings is an important concern in protection coordination in power systems. In this study, optimisation of DOR settings, namely time dial setting and pickup current (I p) setting is achieved by adopting symbiotic organism search technique which is a recently proposed proficient optimiser imitating biological give and take policy while searching for an optimum. Computational ability of the technique to coordinate DORs is validated in IEEE 6-bus and WSCC 9-bus test systems. Results show that the new technique causes for notable reduction in relays’ operating time, with maintaining reliable coordination margin for each primary/backup relay pair, in comparison with other techniques. Also, computation time to find optimum solution is less using the new method.

A high-performance hybrid algorithm to solve the optimal coordination of overcurrent relays in radial distribution networks considering several curve shapes

The coordination of overcurrent relays (OCRs) is essential for improving reliability and security indicators in electrical networks. This paper proposes a high-performance hybrid algorithm (HPHA) to solve the optimal coordination of OCRs in radial distribution networks (RDNs). The optimal coordination problem is formulated as a mixed-integer nonlinear problem (MINLP). We considering as decision variables: (1) the pickup current (Ip); (2) time dial setting (TDS); (3) relay type; (4) curve type. The HPHA is composed of a specialized genetic algorithm (SGA) and an efficient heuristic algorithm (EHA). Thus, the HPHA finds the optimum combination of Ip, TDS, relay types and curve types that minimize the relays operational times, ensuring the selectivity for several fault levels. The proposed algorithm considers discrete values of Ip and TDS. The simulation results showed that the proposed technique is efficient, fast, reliable and improves the coordination by decreasing the operational times of OCRs.

Optimal Coordination of DOCR for Radial Distribution Systems in Presence of TCSC

&lt;p&gt;Protective relays coordination is the process of determining the exact relay settings such that the relay closes to the fault would operates faster than other relays. The operating time of each relay depends on two independent variables called Pickup current (Ip) and Time Dial Setting (TDS). In this paper, a PSO algorithm has been presented to determine the coordination of Directional Over-Current Relays (DOCRs) in presence of multi-system FACTS devises. From the simulation result and analysis, the impact of TCSC location in the in 33-bus distribution system on Directional Over-Current Relays has been observed on the optimal relays settings as well as the effectiveness of the proposed algorithm in finding optimal coordination of directional over-current relays.&lt;/p&gt;

Hybrid GSA‐SQP algorithm for optimal coordination of directional overcurrent relays

This study presents a hybrid gravitational search algorithm-sequential quadratic programming (GSA-SQP) algorithm based on the GSAand SQP to optimal coordination of directional overcurrent relays (DOCRs). The SQP routine is incorporated in GSA as a local search mechanism to improve the performance of the conventional GSA algorithm. The coordination between DOCRs is formulated as a non-linear and highly constrained optimisation problem in which two settings namely time dial setting and pick up current setting of each relay are considered as decision variables. The main objective is to minimise the sum of operating times of all the primary relays, which are expected to operate in order to clear the faults of their corresponding zones. Performance of this approach is studied and evaluated on three different test systems with 6, 24 and 38 relays. Simulation results show that the proposed approach provides effective and robust high-quality solution of the problem.

Alfaxalone for total intravenous anaesthesia in bitches undergoing elective caesarean section and its effects on puppies: a randomized clinical trial

ObjectiveTo evaluate the effects and reliability of alfaxalone constant rate infusion (CRI) in comparison to isoflurane to maintain anaesthesia in bitches undergoing elective caesarean section. Study designProspective, randomized, ‘blinded’ clinical trial. AnimalsTwenty-two client-owned bitches and 94 puppies. MethodsBitches were randomly assigned to receive an alfaxalone CRI [0.2 mg kg-1 minute-1 intravenously (IV), and once the last puppy was delivered, the dose was halved; n = 11] or 2% (vaporizer dial setting) isoflurane (n = 11) for maintenance of anaesthesia. All dogs were induced with alfaxalone (3 mg kg-1) IV. Additional alfaxalone (0.3 mg kg-1 IV) was administered if the depth of anaesthesia was inadequate and the total dose was calculated. Bitches were mechanically ventilated. Analgesia was administered after the delivery of puppies. Physiological variables were recorded every 5 minutes. The bitches’ recovery times were also recorded. Quality of induction and recovery were evaluated. Puppies’ vigour was evaluated with a modified Apgar score at 5 and 60 minutes after birth. Puppies’ survival rates at 24 and 48 hours and at 15 days were recorded. Data were analysed using an anova, Student’s t-test or Wilcoxon rank-sum test. ResultsThe rescue dose of alfaxalone was higher (p = 0.01); bitches’ recoveries were longer (p < 0.001) and puppies’ Apgar scores were significantly lower at 5 and 60 minutes (p < 0.001 and p = 0.003, respectively) with alfaxalone than with isoflurane. However, no significant differences were found for puppies’ survival between groups. Conclusions and clinical relevanceAlfaxalone CRI seems to be a possible protocol for puppies and bitches undergoing elective caesarean sections. However, bitches recovered more slowly and puppy Apgar scores were lower in comparison to isoflurane.

A comparative study on the computation of directional overcurrent relay coordination in power systems using PSO and TLBO based optimization

Purpose Directional Overcurrent Relay (DOCR) coordination computation allowing for desired and high level accuracy in interconnected power systems is very difficult and is a highly constraint oriented optimization problem. This paper aims to study the effectiveness of a newly reported optimization technique, Teaching Learning Based Optimization (TLBO), in protective relay coordination comparing with a widely used optimization technique, Particle Swarm Optimization (PSO). Design/methodology/approach DOCR coordination in electric power systems is considered as an optimization problem by formulating objective function and specifying problem constraints. Optimum values of the DOCR adjustment parameters (Time Dial Setting and Plug Setting) in terms of reliable coordination margin and operating times of relays are computed by both the algorithms, TLBO and PSO. Optimal coordination is verified in three test bus systems: IEEE 6-bus, WSCC 9-bus and IEEE 14-bus systems. Findings A comparison between the numerical results of using both the algorithms indicates that the TLBO gives better results in terms of the total operating times of relays and Coordination Time Interval (CTI). Originality/value This paper represents the performance of a newly reported optimization technique, TLBO which is till now unpopular to protection engineers to be applied in protective relay coordination applications. The technique provides better performance in comparison to the widely applied technique, PSO. It is expected that TLBO would facilitate protection engineers to decide the optimum and appropriate settings of the relays for leading exact relays coordination.