Pickup Current Setting Research Articles

A new and effective directional overcurrent relay coordination approach for IIDG-based distribution networks using different setting groups for peak and off-peak demand periods

Directional overcurrent relays (DOCRs) must be properly coordinated to avoid vulnerabilities in the protection of distribution systems. Although most researchers have focused on changes in fault currents caused by distributed generation units (DGs), changes in load currents are also important. Due to the stochastic nature of load demand and output power of renewable-based DGs, load current magnitudes can change significantly and reach high values throughout the day. Therefore, to avoid maloperation, high pickup current settings for DOCRs must be selected. However, at this time, protection coordination may become ineffective. This paper proposes a novel DOCR coordination strategy for inverter-interfaced DG (IIDG)-based distribution systems by assigning different setting groups to each DOCR for the peak and off-peak loading periods of the day and using a realistic approach to determine maximum load currents. The aim is to achieve high effectiveness in DOCR coordination by lowering selectable pickup settings. To obtain the optimal setting groups, a new variant of the white shark optimizer is developed and used. The proposed approach reduces the total operating time of relay pairs by up to 24.5 % and 21.5 % for the IEEE 14-bus and IEEE 30-bus distribution systems, respectively, compared to the traditional coordination approach.

Coordination of Directional Overcurrent Relays using Growth Optimizer

The protection system plays a crucial role in the generation, transmission, and distribution systems of a power network. Among various protection relay types, Directional Overcurrent Relays (DOCRs) are the most used. When abnormal conditions are detected, these relays trigger the tripping of protection devices by detecting the direction and magnitude of current flow and isolating faulty parts of the system. The present article proposes a novel approach for the coordination and settings of DOCRs using the Growth Optimizer (GO) algorithm; the main objective is to minimize the sum of operation time of the relays while ensuring the minimal time gap between primary and backup relays. This optimization problem is subject to different constraints including maximum allowable operating times, relay coordination margins, and discrete values for pickup current settings. The technique is applied to the IEEE 4-bus, 8-bus, and 15-bus test systems, and its performance is compared with that of other optimization algorithms. Results show that the proposed approach provides the proper coordination of protection systems with a high, robust, and computationally acceptable speed of convergence.

Optimum Overcurrent Relay Coordination Using Genetic Algorithm with Time Multiplier Setting and Pick-Up Current Setting as Variables

Optimum Overcurrent Relay Coordination Using Genetic Algorithm with Time Multiplier Setting and Pick-Up Current Setting as Variables

Adaptive Directional Overcurrent Relay Coordination in Microgrid Considering Optimal Full Setting Parameters

This article proposes a novel approach for the optimal coordination of adaptive directional overcurrent relay (ADOCR) for modernized active distribution system (ADS) with microgrid (MG) functions. The goal is to keep the coordinating circumstances while reducing the protective relay operation time, as much as possible. With the proposed round-off mixed-integer particle swarm optimization (ROMI-PSO), the setting parameters are not limited to only relay time multiplier setting (TMS) and pickup current setting (PS) but can include the discrete parameter as relay characteristic curve setting (CS). In the proposed framework, The CS can be both IEC and IEEE standard curves in the proposed framework. Four buses radial system and IEC-benchmark MG system were used in a number of simulation experiments. Comparing the suggested methodology to other current methods revealed that it is more effective at determining the minimum relay operating times and ensuring the proper operation of protections under various fault allocations and operating circumstances.

AC Microgrids Protection: A Digital Coordinated Adaptive Scheme

A significant challenge for designing a coordinated and effective protection architecture of a microgrid (MG) is the aim of an efficient, reliable, and fast protection scheme for both the grid-connected and islanded modes of operation. To this end, bidirectional power flow, varying short-circuit power, low voltage ride-through (LVRT) capability, and the plug-and-play characteristics of distributed generation units (DGUs), which are key issues in a MG system must be considered; otherwise, a mal-operation of protection devices (PDs) may occur. In this sense, a conventional protection system with a single threshold/setting may not be able to fully protect an MG system. To tackle this challenge, this work presents a comprehensive coordinated adaptive protection scheme for AC MGs that can tune their protection setting according to the system states and the operation mode, and is able to switch the PDs’ setting. In the first step of the proposed adaptive algorithm, an offline setting will be adopted for selective and sensitive fault detection, isolation, and coordination among proposed protective modules. As any change in the system is detected by the proposed algorithm in the online step, a new set of setting for proposed modules will be performed to adapt the settings accordingly. In this way, a new set of settings are adapted to maintain a fast and reliable operation, which covers selective, sensitive, and adaptive requirements. The pickup current (Ip) and time multiple settings (TMS) of directional over-current relays (DOCR), as well as coordinated time delays for the proposed protection scheme for both of the grid-connected and islanded modes of operation, are calculated offline. Then, an online adaptive protection scheme is proposed to detect different fault types in different locations. The simulation results show that the proposed method provides a coordinated reliable solution, which can detect and isolate fault conditions in a fast, selective and coordinated adaptive pattern.

Application of PSO for optimal coordination of directional over-current relays in distribution system with distributed renewable energy sources

<p>The use of Distributed Renewable Energy Sources in the electrical network has expanded greatly. But, integration of these resources into distribution systems caused more problems in protection related issues such as mis-coordination, and changes the direction and value of fault currents. When connecting new D-RES to electrical power distribution networks, it is required to re-coordinate Directional Over-CurrentRelays (DOC-Relays) to ensure the continuity of the power transmission when the short circuits take place. This work presented a Particle Swarm Optimization (PSO) algorithm to determine two independent variables called Pickup current (Ip) and Time Dial Setting (TDS) for optimal setting of relays. From analysis result, the impacts of RES location in the distribution system on DOCRs had been observed on the optimal relays settings</p>

A New Communication-Free Dual Setting Protection Coordination of Microgrid

Protection coordination for the microgrid system in both islanded and grid connected modes is considered a challenge for microgrid operation. The variation in short circuit currents in each mode of operation, limitation of protection curves in the relays, and the need for fast and reliable communication are the main challenges tackled in research. Direction overcurrent relays are considered the main protection instrument for the microgrid. However, one protection setting for both (main and backup) operation does not provide a fast-operating time. On the contrary, the dependence on communication to maintain the proper backup protection operation is not a reliable solution for protection system. Therefore, this paper introduces a fast, reliable, and simple protection scheme for secure microgrid operation in both islanded and grid connected modes. In this context, one set of protection settings is optimized and used in both modes of operation. A protection setting consists of two time-dial settings and one pickup current setting for each relay. The proposed design technique minimizes the total operating time for both main and backup relays. As all protection functions are executed in the forward direction, no communication is needed among relays. The proposed scheme is tested and verified on a modified portion of IEEE 30 bus test system equipped with distributed generation units. A comparative analysis is carried out and the results demonstrate superior performance by the proposed scheme in comparison with the dual setting scheme with communication.

Hybrid VNS–LP algorithm for online optimal coordination of directional overcurrent relays

Optimal coordination of directional overcurrent relays (DOCRs) in interconnected power systems is a highly constrained, non-convex and non-linear optimisation problem. In this study, use of a series of linear programming (LP) problems in a variable neighbourhood search (VNS) framework is proposed, in which pickup current settings can be considered either as continuous or discrete variables. Therefore, the proposed hybrid algorithm (VNS–LP) is suitable for coordination problem-solving in a network with different types of DOCRs. Furthermore, two versions of the VNS algorithm are proposed, the first of which is very easy to implement, while, the other is somewhat more sophisticated, and at the same time much faster and possibly suitable for online coordination in smart grids applications. One advantage of the second algorithm is that it relies only on elementary arithmetic and requires low RAM, which makes it implementable in any low-level programming environment. This, in turn, can increase the interoperability, which is of crucial importance when automating tasks. The efficiency of the proposed algorithm was investigated in several test systems. Numerical results indicate that the two proposed approaches outperform the previous methods. Moreover, the coordination problem is solved in a reasonably short time using a faster approach.

Implementation of Hybrid ABC-PSO Algorithm for Directional Overcurrent Relays Coordination Problem

In modern power system, protective relays are playing a vital role for protection of the whole system. The efficiency and reliability of whole protection system depends upon the combined and coordinated operation of protective devices such as relays, circuit breakers etc. Moreover, both types of relays viz., primary and backup relays have been used for smooth and reliable operation of the power system from years. A primary directional over current relay (DOCR) is setup for the fast response of any faulty condition. If it fails, then backup relay perform the same task after some time gap. Three different setting such as plug-setting multiplier (PSM), pickup current settings and time multiplier setting (TMS) are required of performing the operation. In this paper, three very popular swarm based meta-heuristic such as particle swarm optimization (PSO), artificial bee colony (ABC) and a recent hybridization of both, i.e., hybrid ABC-PSO have been implemented for the calculation of optimal coordination problem. This coordination problem is treated for continuous settings optimization for TMS and pickup current. An IEEE 8 bus system without grid has been opted for validation of the results. It is evident from the study that the hybrid ABC-PSO based proves to generate optimal solution providing better convergence rate as compared to individual PSO and ABC algorithm.

Optimal Allocation of Distributed Generation Considering Protection

The integration of distributed generation (DG) into the power grid has increased in recent years due to its techno-economic benefits for utilities and consumers. However, due to the fact that distribution systems were not originally designed to accommodate such DG units, many challenges are being faced by utilities to seamlessly integrate them into their systems. One of the critical challenges is their effect on protection system settings and coordination. The DG units will affect the pickup current settings of the protection relays, coordination between the primary and secondary relays, and even the direction of the fault current. Failing to consider DG’s effect on the protection system may lead to serious equipment damage or system failure, causing huge financial setbacks for utilities. To that end, this work proposes a new dynamic approach to optimally allocate different types of DG units over the planning horizon. The objective is to minimize the overall costs of the system while taking into consideration the intermittent nature of renewable DG and the impacts on the protection system. Simulation results have been developed on a typical distribution system to prove the effectiveness of the proposed approach.

Mixed-integer linear programming method for coordination of overcurrent and distance relays incorporating overcurrent relays characteristic selection

Coordination of overcurrent-overcurrent (OC) and overcurrent-distance (Dis) relays is one of the important issues in sub-transmission and distribution networks. In this paper, three approaches based on mixed-integer linear programming (MILP) is proposed for OC-OC and OC-Dis relays’ coordination. Two of these proposed approaches are based on previously presented MILP-based approaches that were introduced for determining time and pickup-current settings in OC-OC relays’ coordination problem. These predefined approaches are developed for obtaining optimal types of OC relays in addition to time and pickup-current settings in OC-OC and OC-Dis relays’ coordination problem. A new MILP-based approach with less variables than the developed approaches is also proposed. This new approach has the ability to reach the best result in the short simulation time. In the new proposed approach, a cubic term which has two binary variables and one continuous variable must be replaced with a linear term. Therefore, a new linearization method is presented for this purpose. Three proposed approaches are implemented on the IEEE 8-buses and the IEEE 30-buses network. It is illustrated that new proposed approach from the point of view of objective function and simulation time is better than other methods especially for large networks. Therefore, new proposed approach is suitable for employing in the computing software as an efficient algorithm for relays’ coordination.

Method to resolve false trip of non‐directional overcurrent relays in radial networks equipped with distributed generators

The connection of distributed generation sources to the distribution network has negative effects on the network protection such as; a false trip of non-directional overcurrent relays. In this study, an offline method is proposed to overcome the false trip issue. In this method, the false trip is modelled as a new set of coordination constraints in the optimal coordination problem. For establishing false trip constraints, pickup current setting and characteristic type of relays are selected in addition to the time multiplier setting. Considering false trip constraints in the coordination problem increases the operating time of relays. Therefore, the optimisation is applied to obtain the settings of non-directional overcurrent relays in order to reduce their operating times in addition to resolving the false trip. Also, three new approaches are defined for pickup current selection based on pickup current range. A combination of genetic algorithm and linear programming technique is used to access optimised responses. Finally, the proposed method is implemented on a sample radial distribution network and the results demonstrated that the occurrence of the false trip was prevented and also the operating time of the relays was reduced to an acceptable level.

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.

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.

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.

Comprehensive coordination of radial distribution network protection in the presence of synchronous distributed generation using fault current limiter

Synchronous Machine-based Distributed Generations (SMDGs) are integrated into distribution networks due to their benefits. However, they may cause problems for protection systems, especially in radial distribution networks. In this paper, a coordination algorithm is proposed to modify Time Multiplier Setting (TMS) and pickup current settings of the protective devices, e.g. overcurrent relays, reclosers and fuses, in order to overcome conventional problems of installing SMDGs, e.g. nuisance tripping and fuses blowing, caused by the reverse fault currents of the SMDGs. The proposed algorithm employs the Fault Current Limiter (FCL), as well as re-coordination algorithm, to restore coordination of protection systems in radial distribution networks with high penetration of SMDGs. For this purpose, a multi-objective optimization algorithm is used to determine the minimum size of FCL and optimal setting of protection system. The algorithm is formulated based on hybrid genetic algorithm (GA) and linear programing (LP) method to reduce computation time. Simulations are carried out on a realistic distribution network, and the results demonstrate that the proposed method provides feasible and effective solutions for optimal coordination restoration, while minimizing the FCL size.

MILP approach for optimal coordination of directional overcurrent relays in interconnected power systems

The coordination problem of directional overcurrent relays (DOCRs) is a non-linear and non-convex optimization one. Until now, several methods based on the heuristics and non-linear programming (NLP) approaches have been proposed for solving the problem. Drawback of these methods is that they are likely to be trapped in local minima. In order to overcome the drawback, in this paper, the problem is formulated as a mixed integer linear programming (MILP) while pickup current setting (Iset) and time multiplier setting (TMS) of relays are considered as optimization variables. This formulation is easier to be solved by branch and bound (B&B) approach, because at each branch there is a linear and convex sub-problem. Furthermore, for the first time, the proposed method is guaranteed to converge to global optimal settings. The proposed method is evaluated using a 3-bus, an 8-bus, the IEEE 14-bus and the modified IEEE 30-bus test systems. The results are compared with some previous heuristics and NLP approaches. Based on the obtained results, it can be seen that, better optimal settings for DOCRs are obtained by using the proposed method in comparison with previous methods.

A hybrid improved harmony search algorithm-nonlinear programming approach for optimal coordination of directional overcurrent relays including characteristic selection

The objective of optimal coordination of directional overcurrent relays (DOCRs) is to search optimal relay settings. This leads to the minimum operating time of relays for faults in their primary protection zone under the coordination and boundary constraints. In this paper, relay settings are considered as pairs of - pickup current setting (Ip) and time multiplier setting (TMS), plug setting (PS) and TMS - for solving the coordination problem on 8-bus and 15-bus networks. Moreover, a new hybrid improved harmony search algorithm-nonlinear programming (IHSA-NLP) approach is proposed to solve the relay coordination problem. To demonstrate the superiority of IHSA-NLP method, obtained results are compared with the IHSA and existing methods presented in the literature. Also, the effectiveness of the proposed method is evaluated with the coordination problem considering multiple characteristics on IEEE 30-bus network.

A hybrid improved harmony search algorithm-nonlinear programming approach for optimal coordination of directional overcurrent relays including characteristic selection

The objective of optimal coordination of directional overcurrent relays (DOCRs) is to search optimal relay settings. This leads to the minimum operating time of relays for faults in their primary protection zone under the coordination and boundary constraints. In this paper, relay settings are considered as pairs of - pickup current setting (Ip) and time multiplier setting (TMS), plug setting (PS) and TMS - for solving the coordination problem on 8-bus and 15-bus networks. Moreover, a new hybrid improved harmony search algorithm-nonlinear programming (IHSA-NLP) approach is proposed to solve the relay coordination problem. To demonstrate the superiority of IHSA-NLP method, obtained results are compared with the IHSA and existing methods presented in the literature. Also, the effectiveness of the proposed method is evaluated with the coordination problem considering multiple characteristics on IEEE 30-bus network.

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.