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To make an electrical system reliable and cost-effective, its protection coordination is crucial. Protection coordination is a study to determine the trip settings of protective devices. This research proposes protection coordination for Mehran University of Engineering and Technology, Jamshoro, Sindh. This study includes the coordination of relays connected at each department to the main relay connected with the main vacuum circuit breakers (VCB) by using the time characteristic curves (TCC) and time delay setting of relays using ETAP software. This method is used for the trip of a particular circuit breaker at a proper time. Hence, if a fault occurs in any department only that department will be disconnected, and the rest of the departments will remain in a working condition. This study helps to maintain the system’s high reliability.

This project deals with the realization of Mathematical Modeling and simulation in MATLAB of Differential Protection in Two-Winding Power Transformers, the same one that will be part of the Salesian Polytechnic University, Guayaquil headquarters; will have the objective of simulating the operating conditions of the protection equipment (SEL 587) found in a Substation, obtaining the equation that governs the differential protection operations of said relay, by theoretically analyzing the system conditions, both under normal conditions and for any fault event (external fault, internal fault) on the primary and / or secondary side of the transformer, facilitating students who are in the last cycles of the Electrical Engineering career, learning the concepts and principles of operation of System protections Electric Power. Este proyecto trata sobre la realización del Modelado Matemático y simulación en MATLAB de Protección Diferencial en Transformadores de Potencia de Dos Devanados, el mismo que formará parte de la Universidad Politécnica Salesiana, sede Guayaquil; tendrá como objetivo simular las condiciones de operación de los equipos de protección (SEL 587) que se encuentran en una Subestación, obteniendo la ecuación que rige las operaciones de protección diferencial de dicho relé, mediante el análisis teórico de las condiciones del sistema, tanto en condiciones normales como ante cualquier falla. evento (falla externa, falla interna) en el lado primario y/o secundario del transformador, facilitando a los estudiantes que se encuentran en los últimos ciclos de la carrera de Ingeniería Eléctrica, el aprendizaje de los conceptos y principios de funcionamiento de las protecciones del Sistema de Energía Eléctrica.

This thesis was submitted for the award of Master of Philosophy and was awarded by Brunel University London A well-designed protection system in a power distribution system ensures the continuity of power delivery. Even though this can't prevent a fault, which can lead to a catastrophic situation when the protection will not operate correctly, therefore, protection devices must be correctly selected and installed to avoid these consequences. The power system in a data centre is constructed of prominent features like generators, power supply cables, high and low-voltage transformers, and UPSs with a battery backup system and protection system. Researchers have looked at the problems in terms of faults inside a UPS system which is about protecting the UPS unit itself rather than the power distribution system within the Data Centre. If the fault occurs inside the UPS unit, then internal protection will shut down the faulty unit, and a redundant UPS N+1 will turn on. Operation of the UPS system with “in use” redundancy of the UPS is a critical moment for power delivery security. If the redundant UPS is lost, power backup is lost, so engineers must do repairs quickly. I concentrated on the protection system within the power distribution network in a data centre, not internally to a UPS. The thesis presents the coordination of a protection system with the help of using the ETAP 21 software. The designed power system level is 11kV/400V AC with 50Hz frequency and a capacity of up to 8MW connected to two different DNO grid power networks. The power distribution system includes a backup system to ensure continuity of supply when both DNOs supplies have outages. The simulated protection coordination into randomly selected equipment, line or busbar under the fault condition will show the sequence of the operation. The primary protection has been designed to operate first as it is closer to the fault. However, when it fails to operate, then backup devices in the sequence must operate to isolate the faulty equipment. Protection elements like fuses and circuit breakers are not designed to prevent the fault. The protection, however, senses and operates fast to limit the fault current severity that causes damage to the equipment and increases the system's safety. An integrated part of achieving those is selecting appropriately rated protection devices and switchgear and performing a protection study. Regular maintenance is essential to correctly working the power system and the protection.

The rapid increase of the electrical power demand gave rise to many challenging situations for power system control engineers as the transmission lines are operating at their maximum capacity in most developing economies. To solve this, Distributed Generation (DG), i.e. the generation of electrical power in a distribution network that provides clean energy, is gaining popularity. There are several challenges the protection of distribution networks faces after DG installation, such as variations in short circuit levels, protection blinding, reverse power flow, protection coordination, change in fault impedance, recloser-fuse coordination, selectivity, unsynchronized reclosing, false tripping, etc. In this paper, an IEEE 13-Bus System Radial Distribution System is simulated using Electrical Transient Analyzer Program (ETAP), various scenarios of DG placement are considered, their impact on the protection system is analyzed, and different techniques are proposed to minimize the effect on protection coordination. The use of directional relays, current limiting reactors, and small magnitude DGs is tested and analyzed. The way this effect varies by changing the location of DG is also analyzed.

Due to the expansion of the use of distributed generation sources and especially renewable energy resources, the use of microgrids is increasing rapidly. The protection of DC microgrids is one of the most important challenges in the design and operation of this type of electrical network. In this paper, a new protection method based on Fourier transform with fault detection capability in different operating conditions is presented. The advantages of the proposed method in comparison with the methods of current change rate, etc., are the speed of its protective operation and the ability to detect faults with high impedance and resistance. The directional protection capability of the proposed method and the coordination of protection equipment are other advantages of the proposed method. The results of the implementation of the proposed method on a sample DC microgrid indicate the efficiency of the proposed method in different operating conditions, fault resistance, etc.

With the increasing penetration of distributed generations, preserving the protection system coordination is of great importance for the distribution network operation. This paper presents a supplementary protection strategy for the multi-agent system (MAS)-based hierarchical protection scheme (HPS). The primary level of MAS-based HPS clears the fault and preserves the protection coordination while the higher levels update the relay settings. The key advantage of the proposed supplementary scheme is that the primary level can autonomously and quickly preserve the protection coordination when the main relay is during the time-consuming process of updating settings in the case of network operating condition change. By adopting converter-based DGs as the only MAS agents, the proposed supplementary scheme divides the distribution network into several zones that communicate together using point-to-point communication. Without communicating with higher protection levels, the supplementary protection limits the influence of DGs on the fault current by controlling the produced power of each zone. The effectiveness of the proposed strategy is validated through several simulation case studies on the Isfahan distribution network.

The high-voltage direct current (HVDC) grid has been recognized as an effective solution for renewable energy integration. Currently, two main development trends for HVDC grids are being studied: a DC breaker based HVDC grid and fault-blocking converter based HVDC grid. Although the former has a perfect performance for fault clearance, its development is still highly constrained by the cost and maturity of DC breakers. The latter can extinguish DC faults by the fault-blocking converters. Without using DC breakers, there is no bottleneck in its technical feasibility. Nevertheless, in fault scenarios, such types of HVDC grids will be blocked at length for air-deionization, which is its main drawback. The aim of this paper is to minimize its power interruption time, by optimizing protection coordination strategies. To cover the most complex cases, the overhead line applications, in which the reclosure actions are required to be implemented, are considered. In this paper, the protection requirements of HVDC grids are first discussed, then the benefits of fault-blocking modular multilevel converters (MMCs) and their fault features are analyzed. Based on this, a control function is designed to reduce the air-deionization time. To minimize the influence of the DC faults, a separation methodology for restarting the system is proposed. The effectiveness of the proposed protection coordination schemes is validated by PSCAD/EMTDC simulations.

Research on network reconfiguration (NR) considering distributed generations (DG) is typically concerns on the issues of power loss, voltage deviation, DG sizing as well as its placement, which are important and required in the planning stage. On the other hand, another important aspect which often neglected in this stage is coordination of protection devices which is essential to prevent the network from damages following system breakdown. Without sufficient attention given to the protection coordination during NR, there is a possibility for the protective devices to miscoordinate and consequently lead to system blackout, due to changes in current flow and fault level. Therefore, this paper proposed an NR method for distribution networks with DG, incorporating protection devices. The proposed method aims to find the optimal configuration and DG size with minimum power loss, and at the same time ensuring protective devices operate correctly during normal and fault condition. Constraints on protection coordination and DG size are explicitly formulated in the proposed method. The validity of the proposed method is analyzed on three commonly used IEEE 33-bus, 69-bus and 118-bus distribution systems, employing the firefly algorithm (FA) and evolutionary programming (EP) algorithm. Comparative studies are done to prove the validity and robustness of the proposed method.

The present study is focussed on a comparative analysis of different meta-heuristic optimization approaches for directional overcurrent relay (DOCRs) coordination which has been discussed and presented in the literature. Further, to have a comparative analysis of the performance of the optimization methods discussed they have been tested on power system network of different sizes. To overcome such issues, this work proposed a simplex linear programming technique-based overcurrent relay method using general algebraic modelling system (GAMS). The execution of this work is done on the MATLAB 2018 a platform. Based on the obtained result the best meta-heuristic optimization method for mitigating the problem of relay coordination has been identified. Nevertheless, the operating time of the relay is high, so the fault is not corrected at a time. The developed model has been tested on test system of different sizes namely IEEE 9 bus and IEEE 14 bus system. The obtained values through series of simulation are compared with different methods for proving the proposed protection coordination scheme is more effective and efficient than others in terms of operating time and coordination time.

Many sophisticated software are available to analyse the design of electrical power systems. Therefore, it becomes relevant to know rules of the thumb to be able to diagnose in an elementary and intuitive way the computerized results.For the short circuit analysis, in most practical cases, it is sufficient to adopt simplified and standard based calculation methods. For these cases, the paper introduces the parameter of the countercurrents and illustrates the approach of the short-circuit models of power system components based on the "characteristic" currents method CCM. The paper, at first, presents a short overview of the IEC Std 60909, assumed as reference for the proposed approach.

With the widespread of using distributed generation, the connection of DGs in the distribution system causes miscoordination between protective devices. This paper introduces the problems associated with recloser fuse miscoordination (RFM) in the presence of single and multiple DG in a radial distribution system. Two Multi objective optimization problems are presented. The first is based on technical impacts to determine the optimal size and location of DG considering system power loss reduction and enhancement the voltage profile with a certain constraints and the second is used for minimizing the operating time of all fuses and recloser with obtaining the optimum settings of fuse recloser coordination characteristics. Whale Optimizer algorithm (WOA) emulated RFM as an optimization problem. The performance of the proposed methodology is applied to the standard IEEE 33 node test system. The results show the robustness of the proposed algorithm for solving the RFM problem with achieving system power loss reduction and voltage profile enhancement.&nbsp

Power distribution networks are vulnerable to different faults, which compromise the grid performance and need to be managed effectively. Automatic and accurate fault detection and location are key components of effective fault management. This paper proposes a new framework for fault detection and location for smart distribution networks that are equipped with data loggers. The framework supports networks with mixed overhead lines and underground cables. The proposed framework consists of area detection, faulty section identification, and high impedance fault location. Firstly, the faulty zone and section are detected based on the operation of over-current relays and digital fault recorders. Then, by comparing the recorded traveling times at both ends of lines, which are related to the protection zone, the faulty line is identified. In the last step, the location of the fault is estimated based on discrete wavelet transform. The proposed method is tested on a 20 kV 13 node network, which is composed of overhead lines and underground cables. The method is tested in both balanced and unbalanced configurations. The obtained results confirm the advantages of the proposed method compared with the current state-of-the art.

Due to advances in smart grid, different communication links as delay, inter-trip and activation are used between relays to enhance the protection system performance. In this paper, the effect of inter-trip links on optimal coordination of directional overcurrent relays (DOCRs) is analytically investigated and modelled. Moreover, an index is proposed to find the optimum locations for inter-trip link installation to reach the minimal fault clearance times under the selectivity constraint. Then a method is proposed to determine the candidate locations of inter-trip links and the associated reduced operating times. An Exhaustive search approach is also used to validate the efficiency of the proposed method. The method is simulated and tested on distribution network of IEEE 33 bus using the Power Factory software and MATLAB optimization toolbox. Genetic algorithm is used as an optimization tool to find optimal settings of relays. The results indicate the capability of proposed method in optimal protection coordination with optimum inter-trips.

Protection of electrical network of an industrial complex is a challenging task in particular in connection to the power grid. This paper is focused on this challenging task and reports on the experience of protection coordination assessment and improvement of electrical network of South Pars Gas Complex (SPGC) and in particular the third south Pars refinery. Today South Pars is the economic hub and heart of the gas and petrochemical industry in Iran. The continuous and stable production of gas from the South Pars Gas Field is very important. In order to supply power to the third south Pars refinery four gas turbine generators (GTG) each with a capacity of 41.1MW and two emergency diesel generators (EDG) each with a capacity of 4.5 MW have been installed. In addition to this, one external line to connect the plant to the power grid is considered. Now the third refinery as an island electrical network operates independently from the power grid and provides energy needs of the refinery process and utility units. By connecting the refinery's electrical network to the power grid short-circuit current value increases. If an error occurs on the internal network when the refinery is connected to the power grid, the fault current will be higher compared to when the Refinery works in island mode. This is because current is also injected from the power grid to the faulty point. In this paper, the third south Pars refinery protection coordination in connection to the power grid will be assessed. The ETAP software will be used for the simulation. While the paper reports the practical experience in relation to this particular case study, the approach and experience helps to face the practical challenges in similar projects.

The design of reliable protection systems is essential in order to guarantee the secure operation of power systems. The coordination of the response of protective equipment under fault conditions is a fundamental problem which is usually formulated as a non-linear optimization problem with the objective of minimizing the total operating time of the protection system. In general, optimal protection coordination can be regarded as a well-studied problem, with the existing literature featuring the application of a wide range of solution techniques. However, recent advances in the area of artificial intelligence and the increasing availability of near real-time measurements from distribution systems offer the possibility to envision adaptive protection systems capable of operating optimally under different power system operating conditions and, potentially, of being more resilient, by assigning local decision-making autonomy to relays, instead of relying on a centralized system to coordinate protective devices. To this end, in this study optimal protection coordination is cast as a reinforcement learning problem and relays are viewed as autonomous agents that can manipulate their time dial settings in order to optimally respond to signals from their environment, i.e., the power system. The reinforcement learning problem is solved by applying the Q-learning algorithm. The results of the case study indicate that this framework is capable of providing settings that achieve both a fast and coordinated protection system.

Unlike conventional grids, microgrids may utilize different connections and the overall topology can be variable. Considering this, it is required to develop a new protection concept/scheme for safe operation. Maintaining proper selective operation of the relays in these dynamic microgrid structures is a challenge itself. This requires monitoring the connections and updating time delays of the relays which will ensure the desired hierarchy in the system. In this paper, a novel approach has been taken where electrical networks are modeled according to graph theory. Smart algorithms, such as network graph discovery, local manager selection, and protection coordination strategy, are run to automatically detect topology changes and ensure proper protection operation. Furthermore, distributed nature of this method mitigates the risks associated with central controller-based schemes. The developed method is applicable to all power system operations, and it poses a unique implementation in postdisaster recovery. After a disaster or terror attack, this self-diagnosis, self-healing system can identify healthy sections and run them as a standalone system until the relief arrives. The ability of the protection system to be run as a distributed control makes sure that any healthy part of the system can be restructured and utilized, without the dependency, on any central controller or connection.

Microgrid implementation draws new challenges especially in the coordination of protective devices that are not likely to appear in a traditional distribution network. Variation of fault current levels, bi-directional fault current and changing of microgrid operation modes make protection of the microgrids more difficult. In this work, a systematic procedure for coordination of different protection schemes is presented to secure the operation of a microgrid system. The procedure initially starts with coordination of overcurrent (OC) relays and followed by directional overcurrent (DOC) relays in the system. If the coordination of these two types of relays is unsatisfactory, then differential (DIF) relays are used to replace the OC relay in the faulty section. The proposed method takes into account device selectivity, sensitivity and proper protection function simultaneously. Simulation results show that the proposed coordination method safely protect a microgrid system during both grid-connected and islanded operation modes.

In a conventional distribution system, protection algorithms are designed to operate on a unidirectional high fault-current level. In a microgrid, a fault current from distributed generation (DG) may bring about a relay malfunction because of the bidirectional and relatively small fault current. Therefore, the conventional protection scheme is not applicable to microgrids and a new protection method must be developed. In this paper, two protection coordination algorithms which can be applied for facility and secondary microgrids are proposed, respectively. The proposed protection algorithms eliminate faults not by the EMS signal but by directional relays. Moreover, this makes the algorithms flexible regardless of the types and numbers of DG. The proposed protection algorithms were simulated at the KEPCO RI Microgrid Demonstration Site.

In the recent years the electrical power networks are undergoing rapid restructuring and developing process worldwide. Advancement in technologies and concern about the environmental impacts have led to increase interconnection of renewable energy based distributed generations (DGs) in distribution networks. The DGs have significant impacts on the distribution systems; these impacts may be either positively or negatively depending on the modified interconnected DG distribution network structure. It will be necessary to consider many issues concerning these impacts. In this paper, an investigation of DGs impacts on voltage profile, power losses, and protection system in radial distribution networks is introduced and explained. The performance of the interconnected DG distribution network in terms of power losses, voltage profile and fault currents is analyzed; the penetration level of interconnected DG is used as a parameter in order to verify the effects on these issues. A comparison between many cases with different numbers, sizes and locations of interconnected DGs are considered and discussed. Detailed simulations using MATLAB are conducted in order to explain and verify the results.

For short-circuit analysis in industrial and commercial power systems, a new approach of the ohmic method in such a form as to facilitate, as far as possible, its use and the realization of its evaluation is suggested. The 'characteristic' current method, by replacing the impedance of each equipment with the corresponding value of the 'characteristic' current, permits the application of the impedance properties to the inverse of the current values, either in meshed or nonmeshed networks. In order to achieve the correct design, rating and protection coordination of the whole power system, it is necessary to know and calculate step by step the values of short circuit current for each system component, from the utility or local generating connection point until the branch-circuits and the utilization equipments. The proposed approach assumes the above mentioned short-circuit current directly as calculation and comparison parameters. With the 'characteristic' currents as parameters the short-circuit analysis of substantial radial systems is made easier and a better matching of power system design requirements is permitted. >

DC shipboard power systems have been considered as a promising solution for stricter environmental regulations on ships due to their main benefits in fuel savings with variable speed engines and easy integration of energy storage systems. In order to employ the dc solution in the shipboard power systems, the dc power systems have to be protected from a system fault with protection selectivity to minimize impacts of the fault or to avoid other undesirable situations in the system. For low-voltage dc shipboard power systems, a three-level protection has been proposed: 1) fast action (first)—bus separation by solid-state dc bus-tie switch; 2) medium action (second)—feeder protection by high-speed fuse; and 3) slow action (third)—generator–rectifier fault controls. This paper proposes a new method by means of additional bus capacitance added in main dc buses to help reliable operation of the three-level protection. The principle of the proposed method is introduced and the sizing of the additional bus capacitance is addressed in this paper. With the modeling of the dc shipboard power systems, the analyses of voltage drops for the bus separation failure and fault clearing time for the feeder protection are carried out to verify the proposed method. The results show that the proposed method not only mitigates the voltage drop for the bus separation failure, but also achieves the selectivity and the sensitivity for the feeder protection.

WOS: 000418818000015, Protection coordination is the heart of all power systems. To ensure a quality and reliable operation of the power systems, an electrical fault must be cleared within a short time. This can be achieved by proper coordination between the protection relays. In Siddik Kardesler Substation the MV voltage feeders' protection is provided by overcurrent relays. This paper is principally concerned with practical protection coordination of the electrical substation by using Siddik Kardesler Substation substation as a case study. In the Part-2, distance and differential protection will be discussed. Finally, after test and commissioning, the substation is successfully energized without a problem.

WOS: 000418818000014, Power systems must be protected against faults to ensure quality and reliable generation, transmission and distribution of power systems. Power system protection is provided by the protection relays. This paper is the second part of the Protection Coordination study for the Siddik Kardesler Substation. The protection for transmission lines, transformer, bus bars and customer feeders is provided by overcurrent protection, differential and distance protection schemes. In this paper, issues related to the Differential Protection and Distance Protection for the substation will be discussed. Finally, the test and commissioning have been conducted and the substation is successfully energized without a problem