Time Dial Setting Research Articles

Modified Particle Swarm Optimizer as Optimization of Time Dial Settings for Coordination of Directional Overcurrent Relay

The coordination of directional overcurrent relays (DOCR) plays a very important role for maintaining security and enhancing reliability in the electrical power system. This paper presents the coordination of directional overcurrent relay using the modified particle swarm optimization (MPSO) technique. In order to improve the quality of a solution a local search algorithm is embedded to the original particle swarm optimization (PSO). Time dial settings had been optimized for directional overcurrent relays. In PSO technique on implementing the DOCR, being a highly constrained optimization problem that takes into consideration the linear programming. To handle such constraints a modification to PSO algorithm has been introduced. MPSO has achieved a lot of relaxation to its easy implementation, modesty and robustness. The proposed algorithm had been tested on IEEE 6-bus, IEEE 15-bus system and IEEE 30-bus system using MATLAB computer programming.

Oppositional Jaya Algorithm With Distance-Adaptive Coefficient in Solving Directional Over Current Relays Coordination Problem

The model of directional over current relays (DOCRs) coordination is considered as an optimization problem. It is generally formulated as linear programming (LP), non-linear programming (NLP) and mixed integer non-linear programming (MINLP), according to the nature of the design variables. For each kind of formulation, the main goal is to minimize the summation of operating times of primary relays, by setting optimal values for decision variables as time dial setting (TDS) and pickup current setting (IP) or plug setting (PS). In this paper, we proposed an oppositional Jaya (OJaya) algorithm with distance-adaptive coefficient (DAC), to effectively solve the DOCRs coordination problem. Firstly, by oppositional learning (OL), the searching space of Jaya is expanded and the diversity of its population is strengthened; secondly, by DAC, the population's trends of running towards the best position and escaping from the worst position is accelerated. The performance of OJaya is evaluated by 3-bus, 8-bus, 9-bus and 15-bus testing systems, in aspects of convergence rate, objective function value, robustness and computation efficiency. The results indicate the effectiveness and superiority of OJaya in solving DOCRs coordination problems compared with standard Jaya.

Improved Firefly Algorithm for the Optimal Coordination of Directional Overcurrent Relays

In an electrical power network linear and non-linear models are used for directional overcurrent relay (DOCR) coordination issue by applying different heuristic techniques. Nature inspired algorithms (NIA) have found great interest in power system optimization issues. This paper proposes the recently developed meta-heuristic technique known as Firefly Algorithm (FA) that mimics the flashing behavior of fireflies. The implementation of the proposed algorithm has been utilized to solve the coordination of DOCR problems. The main aim of this paper is to find out the optimum values of the Time Dial Setting (TDS) to minimize the relay operating time. The modifications to original FA has been implemented in this paper to solve the DOCR coordination issues. Self-adaptive weight and experience-based learning strategy are added in the original FA, named as improved firefly algorithm (IFA). In IFA, a self-adaptive weight is presented to change the propensity of moving the best solution and ignoring the worst solution. In addition, an experience-based learning system is created and utilized arbitrarily to keep up the populace-assorted variety and improve the exploration capacity. The IFA has been tested on IEEE 6 and 30-bus systems and tested on IEEE 9-bus system for numerical DOCRs and the results had been compared with results of Whale optimization algorithm to validate the performance of IFA in case of numerical DOCR. The obtained results show that the IFA provides efficient and promising results compared to other meta-heuristic techniques mentioned in the literature. The IFA has been successfully implemented on MATLAB software programming.

Modified water cycle algorithm for optimal direction overcurrent relays coordination

The optimization model of Directional Over Current Relays (DOCRs) coordination is considered non-linear optimization problem with a large number of operating constraints. This paper proposes a modified version for Water Cycle Algorithm (WCA), referred to as MWCA to effectively solve the optimal coordination problem of DOCRs. The main goal is to minimize the summation of operating times of all relays when they act as primary protective devices. The operating time of a relay depends on time dial setting and pickup current setting or plug setting, which they are considered as decision variables. In the proposed technique, the search space has been reduced by increasing the C-value of traditional WCA, which effects on the balance between explorative and exploitative phases, gradually during the iterative process in order to find the global minimum. The performance of proposed algorithm is assessed using standard test systems; 8-bus, 9-bus, 15-bus, and 30-bus. The obtained results by the proposed algorithm are compared with those obtained by other well-known optimization techniques. In addition, the proposed algorithm has been validated using benchmark DIgSILENT PowerFactory. The results show the effectiveness and superiority of the proposed algorithm to solve DOCRs coordination problem, compared with traditional WCA and other optimization techniques.

Use of Clustering to Reduce the Number of Different Setting Groups for Adaptive Coordination of Overcurrent Relays

The facility to save multiple setting groups (SGs) within digital overcurrent relays (OCRs) is to adapt the active setting of the relays to the current topology of the power network. However, the number of available SGs is much lower than the possible topologies of the network, so this facility is usually applied to a few local changes in the network. This paper aims to extend the application to a complete set of topologies. A proper index is introduced and applied with a k -means clustering technique to classify the topologies into some clusters, whose number is equal to the number of SGs. Then, for every topology cluster, the optimal settings are calculated and saved in the OCRs as a distinct SG to be activated by changing the topology to any member of the cluster. Applying this technique to OCRs of the IEEE 14-bus test network and a 63/20kV substation verifies its effectiveness on reserving coordination for all topologies and reducing the relays’ time dial setting. Using available communication links, this technique can be implemented by making a computer network between substations of the power network without needing to interact with the control center.

Prototyping and hardware‐in‐loop verification of OCR

This study presents the design and development of a soft-core prototype of an overcurrent relay (OCR). The prototype is implemented on the field programmable gate array and its functionality has been verified using hardware-in-loop testing on the real-time digital simulator. Computational efficiency and memory requirement of the OCR is improved by using integer arithmetic Verilog design platform. Extreme inverse and very inverse characteristics of the OCR based on standard inverse-time characteristics as per IEEE standard C37.112-1996 is used and tested in the proposed design. Digital design of the proposed algorithm, emulation results, complete hardware setup and experimental test results are presented in this study. The performance of the OCR is evaluated for a large range of characteristic parameters (pick-up current and time-dial setting) and various operating conditions which validate the operation of the relay in real time with the power network. The designed relay has the ability to differentiate between fault and inrush current to avoid any mal-operation during energisation of transformers.

Linear programming technique based optimal relay coordination in a radial distribution system

Now-a-days to ensure power continuity and system’s reliability the protection system is to be designed properly for distribution systems to handle the faults to avoiding the damage to the equipments and to the service engineers. Different types of relays with different working principles are used to detect different types of faults in the system. In order to avoid mal operation of relays, proper coordination is to be carried out. The objective of this paper is to maintain the relay coordination as well as to decrease the working time of relays by optimizing the values of time dial setting (TDS) using linear programming problem technique (LPP). The inequality constraints guarantee the coordination margin for each primary or backup relay pairs having a fault very close to the primary relay. Simulation is carried out on a IEEE 15 bus balanced radial distribution system with 3 different types of relays namely standard inverse, extremely inverse and very inverse relay and the results are presented and analyzed.

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.

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.

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 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.

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.

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.

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.

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

<p>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.</p>

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.