Dual Setting Directional Overcurrent Relays Research Articles

Reconfiguration of the real distribution network and providing a new resilience index, considering the uncertainty of renewable energy sources and digital protection devices in order to improve the resilience

Electric energy, as the most widely used form of energy, has always captured human attention to itself; however, with the climate change and the increase of natural phenomena, it is now necessary to provide solutions to improve the resilience of the network. Resilience is defined as the capability of the system to maintain an acceptable level of performance against a severe disturbance and return to its original condition in an appropriate period of time, which demonstrates the degree of endurance, vulnerability, and reversibility of an infrastructure system. The occurrence of adverse weather conditions and natural disasters causes extensive losses and power outages in distribution networks; and the number and severity of such incidents have seen an increase in recent years. Therefore, it is of great significance to evaluate the resilience of the network and its reversibility capability in dealing with adverse weather conditions. In this paper, after defining the concept of resilience in distribution networks, its characteristics are determined; and then, modeling common natural events such as floods and storms, and introducing a new index to evaluate resilience in distribution networks with digital directional overcurrent relays (DOCR) and Digital dual-setting directional overcurrent relays (DS-DOCR) in the presence of renewable energy sources (RES), the proposed scheme is presented.

Enhanced Combined Protection Scheme Using Dual Setting Directional Overcurrent and Distance Relays Considering Severe Line Contingencies

An electrical power system must have an optimal protection system for enhanced reliability. Numerous studies have attempted to address issues with protection schemes, such as coordination constraint violations due to change in network configuration. Furthermore, in a few articles, the N-1 line contingency is considered without considering the line contingency selection criterion, resulting in a large number of constraints to deal with in the optimization problem. This paper proposes a new relay coordination scheme for dual setting directional overcurrent relay (DOCR) and distance relay based on the severity index of line outages, which is calculated by using an active and reactive performance index. The proposed protection strategy is improved with the help of an intelligent selection of the relay characteristics coefficient for dual setting DOCR along with the other relay settings. Another significant contribution is to provide a comparative analysis of standard and user-defined relay characteristics using genetic algorithm and grey wolf optimization algorithms. The modified IEEE-14 bus test system and IEEE-39 bus test system is used to validate the efficacy of the proposed protection scheme.

Protection Coordination of Microgrids Using Dual Setting Directional Overcurrent Relays Based on Optimal Operating Characteristics and Curve Breakpoints

Protection Coordination of Microgrids Using Dual Setting Directional Overcurrent Relays Based on Optimal Operating Characteristics and Curve Breakpoints

Optimized adaptive protection coordination of microgrids by dual-setting directional overcurrent relays considering different topologies based on limited independent relays’ setting groups

• Optimal adaptive protection, considering the limits on the number of setting groups. • Using the DS-DOCRs incorporating independent changes in the setting groups. • Optimal relay curve types and breakpoints for the DS-DOCRs. • Fast protection without selectivity constraint violations in various configurations. • Around 41.66% improvement compared to available studies. Several studies, such as adaptive protection schemes, have been done in the area of smart grids’ protection. However, there is a research gap in developing an adaptive scheme with dual-setting (DS) directional overcurrent relays (DOCRs), considering the limitations of the number of setting groups of protective relays. This research aims to fill such a research gap. Optimizing the relay curve types of the first and second parts of the DS relay models and breakpoints (BPs) improves the speed of the protection scheme based on independent changes in the setting groups of DOCRs. Also, there is no coordination constraint violation in various configurations by applying the proposed method, while it requires only a limited number of setting groups. Therefore, the proposed method can be practical in actual systems because the suggested solutions and protective settings can be easily implemented using commercial relays. The proposed adaptive protection scheme is applied to two test systems (the distribution networks of the IEEE 14-bus and IEEE 30-bus test systems). The comparative test results infer that significant improvement in the speed of the protection system of smart grids can be achieved compared to available studies by the proposed method.

Multi-objective Function Optimization for Locating and Sizing of Renewable Energy Sources and Energy Storages in Radial Distribution Networks with Digital Directional Overcurrent Relays and Digital Dual-setting Directional Overcurrent Relays

Multi-objective Function Optimization for Locating and Sizing of Renewable Energy Sources and Energy Storages in Radial Distribution Networks with Digital Directional Overcurrent Relays and Digital Dual-setting Directional Overcurrent Relays

Coordination of Dual-Setting Overcurrent and Distance Relays for Meshed Distribution Networks with Distributed Generations and Dynamic Voltage Restorer

ABSTRACT Simultaneous coordination of dual-setting directional overcurrent relays (DOCRs) and distance relays (DRs) is capable of providing reliable protection in a meshed distribution network (MDN). However, survey of literature on coordination of DRs and dual-setting DOCRs, reveals changes in system topology, especially in the presence of distributed generations (DGs), affects the coordination. As penetrations of DGs are increasing with time and in few years in a row, MDN with 100% penetration is also possible, an improved coordination of dual-setting DOCRs & DRs is targeted in this work. With nonstandard characteristic of DOCR, an innovative objective function is proposed and explored for optimum settings with particle swarm optimization (PSO) and gray wolf optimization (GWO). With various simulation studies, the performance of the proposed approach is investigated with and without compensation using a dynamic voltage restorer (DVR). The proposed method is validated on modified 14-bus and 39-bus test systems. The simulation results depict that the proposed approach can solve the miscoordination problem and the number of relays, operating time, and coordination time interval (CTI) of relays are also minimized. Comparison with convention approach demonstrates the benefits of proposed approach.

Coordination of dual setting overcurrent relays in microgrid with optimally determined relay characteristics for dual operating modes

Fault current magnitude in a microgrid depends upon its mode of operation, namely, grid-connected mode or islanded mode. Depending on the type of fault in a given mode, separate protection schemes are generally employed. With the change in microgrid operating mode, the protection scheme needs to be modified which is uneconomical and time inefficient. In this paper, a novel optimal protection coordination scheme is proposed, one which enables a common optimal relay setting which is valid in both operating modes of the microgrid. In this context, a common optimal protection scheme is introduced for dual setting directional overcurrent relays (DOCRs) using a combination of various standard relay characteristics. Along with the two variables, i.e., time multiplier setting (TMS) and plug setting (PS) for conventional directional overcurrent relay, dual setting DOCRs are augmented with a third variable of relay characteristics identifier (RCI), which is responsible for selecting optimal relay characteristics from the standard relay characteristics according to the IEC-60255 standard. The relay coordination problem is formulated as a mixed-integer nonlinear programming (MINLP) problem, and the settings of relays are optimally determined using the genetic algorithm (GA) and the grey wolf optimization (GWO) algorithm. To validate the superiority of the proposed protection scheme, the distribution parts of the IEEE-14 and IEEE-30 bus benchmark systems are considered.

Augmenting protection coordination index in interconnected distribution electrical grids: Optimal dual characteristic using numerical relays

One of the most significant tasks of protection coordination of power networks is the satisfaction of coordination between protective equipment. With growing penetration level of distributed generations)DGs), selectivity issue of overcurrent relays is very imperative in active distribution systems .Therefore, sustainable electricity needs to enhance the protection coordination index (PCI). These enhancement will cause the development of DG penetration in power networks. In this paper, time-current-voltage characteristics and dual-setting directional overcurrent relays (DOCRs) are jointly deployed to improve PCI in interconnected distribution networks where the coordination process seems a complex problem. Dual-setting relays can trip in forward and reverse directions with individual settings in both directions which provide proper flexibility to improve PCI. Also, time–current-voltage characteristics employ the voltage parameter in operation time of relays which can decrease the optimization process to cause higher flexibility in the coordination process. besides, the mentioned protection model is developed by user-defined time–current-voltage characteristics to improve PCI. The suggested scheme is modeled and presented as a nonlinear programming approach that is tackled by the genetic algorithm (GA) and comparing performance with Grey Wolf Optimization (GWO). In this paper, to evaluate the performance and scalability of the proposed method, IEEE 14-bus and 30-bus system is applied. The advantage of the proposed scheme is the ability to implement in numerical relays, in which paper is expressed in the form of protection logic and description of respective logic blocks. Results depict the significant improvement in PCI.

User-Defined Dual Setting Directional Overcurrent Relays with Hybrid Time Current-Voltage Characteristics-Based Protection Coordination for Active Distribution Network

With the penetration of renewable energy sources based distributed generation (RES-DG) in the distribution network (DN), the operating time of protection relays becomes a major concern to avoid the mis-coordination and nuisance tripping of RES-DG. It is due to the bidirectional flow of current, variance in the fault current level, i.e. high fault current in case of Squirrel cage induction generator (SCIG) based RES-DG, and low fault current for an inverter-based RES-DGs. This paper proposes a novel User-defined dual setting direction overcurrent relay with hybrid time current-voltage (UDDOR-TCV) characteristics to intensify the proposed scheme’s flexibility without any communication assistance for radial DN. The proposed model is formulated in a constrained non-linear optimization fashion and solved with the MINLP solver of general algebraic modelling system(GAMS) software to determine the optimal relay settings. The propounded protection scheme is simulated on IEEE-33 bus radial distribution system and a local 40-bus system hosting the multiple SCIG and PV based RES-DGs at optimal locations. Detailed numerical studies are carried out to show the performance of the proposed scheme. 66.848% and 68.26% reduction in relay operation time with zero mis-coordination is achieved with SCIG-WTG case and PV-units case for the IEEE-33 bus system and a similar reduction in operation time is 68.937% and 66.563% for Local-40 bus system. Moreover, the relays numbers are reduced by 32.692% and 39.7% for IEEE-33 and Local-40 bus systems, respectively, due to the forward/reverse characteristics capability of the proposed UDDOR-TCV. The performance of the proposed scheme is also evaluated on IEEE-8 bus meshed DN. The results are compared with the existing protection schemes in recent literature.

Optimal dual characteristics for enhancing coordination index in protecting forward and reverse fault currents

Satisfying coordination constraints among protective devices is a challenging task in the protection system of electrical grids. On the other hand, increasing interest on the distributed generations (DGs) jeopardizes the selectivity among overcurrent relays in active distribution networks. Therefore, sustainable electrification requires enhancing the protection coordination index (PCI) in order to increase DG penetration in these networks. In this paper, time–current–voltage​ characteristics and dual-setting directional overcurrent relays (DOCRs) are jointly employed to improve PCI in interconnected distribution networks. Dual-setting relays can operate in forward and reverse directions with individual settings in both directions which help to provide more flexibility in improving PCI. Moreover, the time–current–voltage​ characteristics have the voltage parameter in operation time of relays which can simplify the optimization process to yield higher flexibility in the coordination process. Furthermore, the proposed protection scheme is extended by user-defined time–current–voltage​ characteristics to improve PCI as much as possible. The proposed scheme is formulated as a nonlinear programming model that is solved by the genetic algorithm (GA). The proposed scheme is tested on IEEE 14-bus and 30-bus testbed. Results show a remarkable improvement.

Non-Communication Based Time-Current-Voltage Dual Setting Directional Overcurrent Protection for Radial Distribution Systems With DG

This paper proposes a novel protection scheme equipped with time current voltage dual setting directional overcurrent relays for radial distribution systems with (distributed generation) DG without the need of communication assistance. The proposed protection scheme is formulated as a nonlinear programming problem where the main objective is to determine the optimal relay forward and reverse settings to minimize the relay overall operating times. The proposed scheme, based on the time current voltage dual settings directional overcurrent relay, is applied to the IEEE 33-bus radial distribution system with synchronous-based DG and its performance is compared against the conventional protection schemes that rely on both standard overcurrent relays and time current voltage directional overcurrent relays (proposed in the literature). The results show that, for radial distribution systems, the proposed scheme is capable of mitigating protection coordination failure due to DG reverse fault currents (a limitation in overcurrent relays), does not require communication (a limitation for meshed distribution systems) and does not require additional relays (a limitation in directional overcurrent relays) and thus making such relays more suitable for protecting radial distribution systems with DG.

A dynamic objective function for communication-based relaying: Increasing the controllability of relays settings considering N-1 contingencies

Considering different configurations of a protected network in relays coordination offers higher reliability, security, and sustainability. However, overcurrent relaying in N-1 contingency states stands as a complicated problem especially in interconnected sub-transmissions systems with distance relays. To overcome this challenge, the current paper proposes a coordination scheme in which dual setting directional overcurrent relays (D-DOCRs) and low bandwidth communication links are jointly deployed instead of conventional DOCRs. By doing so, more flexibility and extensibility is provided in the coordination process. Moreover, in order to direct the relays settings toward optimal solutions, a new dynamic objective function is devised. This approach strengthens the controllability of relay settings in different conditions by pulling the variables towards the feasible region. The proposed formulation considers both standard and non-standard relay characteristics and demonstrates a nonlinear programming fashion which is solved by chaotic particle swarm optimization algorithm. Results approve that D-DOCRs in conjunction with distance relays can successfully maintain a proper coordination in N-1 contingency states, supported by the proposed dynamic approach.

Dual-Setting Directional Overcurrent Relays for Protecting Automated Distribution Networks

This paper elaborates a new protection scheme based on dual-setting DOCRs for automated distribution networks. In this course, the reduction in relays operation time saturates as the number of these relays increases. Thus, optimal deployment of dual-setting DOCRs should be specified in an efficient manner. To do so, a multiobjective optimization approach is established, which compromises the reduction of total operation time and the number of dual-setting DOCRs. Coordination constraints are accommodated and nonstandard inverse-time characteristics are established to intensify flexibility of the proposed strategy. The proposed model lies within a nonlinear programming fashion, which is tackled by particle swarm optimization. Moreover, the augmented ε-constraint approach is utilized to reach the Pareto-optimal solutions following which the fuzzy decision making process determines the best compromised solution. Detailed simulation studies are carried out to interrogate performance of the proposed approach.

Optimal coordination of dual‐setting directional over‐current relays in multi‐source meshed active distribution networks considering transient stability

Sustainable electrification calls the need for more efficient protection schemes. Synchronous-based distributed generations (SBDGs) are more susceptible to power grid faults owing to their low inertia time constants. Accordingly, fault elimination faster than the associated critical clearing time (CCT) is required to prevent unintentional disconnection of SBDGs, which inevitably makes the coordination of directional over-current relays (DOCRs) complicated than before, especially in meshed structure distribution networks (DNs). This study proposes communication assisted dual-setting DOCRs as effective solutions for providing fast-response protection in order to meet transient stability constraints of SBDGs in meshed active DNs. Dual-setting DOCRs are capable of operating in both forward and reverse directions with individual settings for each direction and thus providing flexibility in the coordination process. In this regard, time domain simulation as a reliable method is conducted to calculate CCTs. Afterwards, coupled with selectivity constraints associated with dual-setting DOCRs, transient stability constraints are all together accommodated in the optimisation process. Moreover, dual-setting DOCRs are allowed to follow user-defined time-inverse characteristics which help to alleviate clearing time of faults. The approach reveals a non-linear programming model which is tackled by seeker algorithm. Detailed numerical studies are carried out to validate the performance of the proposed approach.

Protection Coordination for Microgrids With Grid-Connected and Islanded Capabilities Using Communication Assisted Dual Setting Directional Overcurrent Relays

This paper proposes a communication assisted dual setting relay protection scheme for micro-grids with grid connected and islanded capability. Previous work on dual setting relays has been applied to grid connected distributed generation systems only, but one major shortcoming is the failure of the backup scheme to operate in a coordinated manner. The proposed scheme relies on the use of dual setting directional overcurrent relays that are capable of operating in both forward and reverse directions, with different settings, and with a low bandwidth communication to maintain proper protection coordination. The problem is formulated as a non-linear constrained programming problem where the relay settings are optimally determined to minimize the overall relay operating time for primary and backup operation. The scheme is tested on a modified version of the IEEE 30 bus test system equipped with distributed generation and with capability of operating in an islanded mode. The proposed scheme is compared against the conventional scheme and the results show that it is capable of overcoming the problem of infeasibility, experienced by the conventional method, without the need of installing fault current limiters. Furthermore, it achieves remarkable reduction in both the primary and backup relay operating times, which was reflected in a reduction in the total relay operating time.

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.

Closure to “Optimal Protection Coordination for Meshed Distribution Systems With DG Using Dual Setting Directional Over-Current Relays”

Closure to “Optimal Protection Coordination for Meshed Distribution Systems With DG Using Dual Setting Directional Over-Current Relays”

Optimal Protection Coordination for Meshed Distribution Systems With DG Using Dual Setting Directional Over-Current Relays

In the presence of distributed generation (DG), it is important to assure a fast and reliable protection system for the distribution network to avoid unintentional DG disconnection during fault conditions. In this paper, dual setting directional over-current relays are proposed for protecting meshed distribution systems with DG. Dual setting relays are equipped with two inverse time-current characteristics whose settings will depend on the fault direction. The protection coordination problem for the dual setting directional relay is formulated as a nonlinear programming problem where the objective is to minimize the overall time of operation of relays during primary and backup operation. The proposed protection coordination scheme using dual setting relays is compared against the conventional approach, which relies on the conventional one setting directional relay. The proposed scheme is applied to the power distribution network of the IEEE 30-bus system equipped with synchronous and inverter-based DG. The results show that the proposed protection coordination scheme with dual setting relay can significantly reduce the overall relay operating time, making it an attractive option for distribution systems with DG.