Coordination Of Distributed Systems Research Articles

An Adaptive Protection Scheme Based on a Modified Heap-Based Optimizer for Distance and Directional Overcurrent Relays Coordination in Distribution Systems

This paper proposes an adaptive protection scheme (APS) based on the original heap-based optimization (HBO) and a modified HBO (MHBO). APS is used to solve protection relays coordination problems that include directional overcurrent relays (DOCRs) as well as the distance relay’s second zone times. The complexity of the coordination problem increases with the impact of distributed generators (DGs) switching (ON/OFF). Topological changes in grid configuration frequently occur in distributing networks, equipped with DGs, causing changes in the values and direction of short circuit currents. This issue becomes a challenge for protection systems to avoid relays miscoordination and save a network’s reliability. In the proposed MHBO, the Original HBO is modified by three points, population are divided into subgroups, then they are unified into one group gradually, those subgroups are exchanging some search agents between themselves, these search agents are called travelling agents, and the last one is about, upgrading an internal equation in the original algorithm. For validating the proposed relays coordination, the IEEE 8-bus test system, and the IEEE 14-bus distribution network are selected as case studies. The obtained simulated results of the proposed algorithm show better performance compared with those obtained by the previous algorithms.

Protection Devices Coordination in Distribution Systems with Microgrids Powered by Renewable Distributed Generation

Protection Devices Coordination in Distribution Systems with Microgrids Powered by Renewable Distributed Generation

Co-optimization of distribution system operation and transmission system planning: A decentralized stochastic solution

The distribution system is normally equivalent as a dynamic power injected at the interconnected transmission bus. This cannot unlock the potential benefits of transmission–distribution interaction. To tackle this problem, this paper proposes a distributed stochastic optimization approach to simultaneously determine distribution system operation and transmission system planning. Uncertainties in the distribution and transmission systems are modelled using numbers of typical scenarios. The original problem is decomposed into the upper transmission network planning level and the lower distribution network operation one. Both two levels are linearized using a piecewise linearization approach to guarantee the convergence properties of the algorithm. Simulation results investigated on the integrated T24D9 system testify the high performance of the presented distributed framework. With the coordination of distribution systems, the transmission network planning solution decreases the investment and improves the renewable energy recommendation.

Optimal coordination of directional overcurrent relays in distribution systems with DGs and FCLs considering voltage sag energy index

Parallel analysis of power quality and protection coordination has become an important part of modern power system studies. Nowadays, the coordination of directional overcurrent relays (DOCRs) is significantly affected by the emerging of distributed generations (DGs). Using voltage sag energy index, a new approach is proposed for optimization of DOCRs coordination in distribution systems in the presence of DGs, Fault current limiters (FCLs), and voltage-sensitive buses. This approach aims to minimize an objective function which comprises three key elements: operating time of relays, voltage sag energy index, and voltage sag duration. The impedance of FCL and the time setting multiplier, current setting and characteristic of DOCRs are the optimization variables. Voltage tolerance curve and voltage sag energy index are also used to show the improvement of voltage sag characteristics and prioritization of answers. Simulation results show that, the operating time of DOCRs and voltage sag characteristics are significantly improved.

Optimal Planning of Fault Current Limiters for Recloser-Fuse Coordination in Distribution Systems with DGs

Optimal Planning of Fault Current Limiters for Recloser-Fuse Coordination in Distribution Systems with DGs

Reverse Power Flow (RPF) Detection and Impact on Protection Coordination of Distribution Systems

Due to the inclusion of distributed generation (DG) in modern power systems, there are certain changes in the distribution and transmission stage, either by impedance reflected by the lines, the increase of short-circuit currents, or the X/R relation, seen from the different nodes on the grid. Such changes have a direct impact on protection coordination, which is the priority of study in this article, but it is important to note that another characteristic affected by the DG is the power quality in terms of voltage sags, swells, and harmonics. One of the significant impacts due to the DG is the reverse power flow (RPF), which generally occurs when the generation of a distributed electric power plant exceeds the local load demand, causing power to flow in the opposite direction to normal. This phenomenon can be produced by the intermittency in the renewable energies, which depends on climatic factors. The consequences can be evidenced in the power system with voltage peaks; therefore, the sensitivity and various parameters of protection coordination are critically affected, which has further implications in the power quality. This work proposes a tool to identify possible scenarios of RPFs and a feasible solution is introduced. A comparative assessment is done to minimize the possibility of an RPF in the IEEE 13 Nodes radial system with conclusive results.

Impact of Renewable Distributed Generation on Protection Coordination of Distribution System

Impact of Renewable Distributed Generation on Protection Coordination of Distribution System

Analysis on Relay Protection Transition Technology and Outer Pre-path Selection Based on PBT

To improve the performance of fault isolation and restoration in distribution grids, the feasibility of relay protection based on time-delay coordination in distribution systems is investigated. Design considerations of hybrid fault isolation and restoration combined by time-delay based relay protection and distribution automation system (DAS) are given. Firstly, the performance indexes of relay protection services are analyzed in four aspects: interface rate, time delay, bit error and channel. Secondly, based on the time delay formulas, the study is focused on the ending/receiving delay and the forwarding and switching delay about PBT transmitting relay protection services. Some commendations such as technology choice and routing configuration are given. Finally, how to choose linear protection switch is studied from the reliability standpoint.

Implementation of adaptive relay coordination in distribution systems including distributed generation

Distribution system is considered as one of the leading part of an electrical power grid structure and it is gaining more importance especially in smart grid concept. The mature structure of distribution systems is evolving due to the high penetration of distributed generation (DG) sources. Conventional protection schemes in distribution systems are prone to potential threats with increasing number of DG units. The characteristics of DG systems such as wind and solar energy conversion systems are generally uncertain in nature. These units add complexity to conventional protections schemes in terms of directional protection challenges. Besides, the integration of DG units to grid results in availability of new local energy sources in the points where loads are connected. Thus, misoperations and imperfect selectivity of relays can occur within the distribution system. These issues call for the need of a bi-directional relay operation and an operation strategy where adaptive protection and relay coordinations are applied in new distribution systems compatible with smart grid necessities. In this paper an adaptive protection scheme is proposed for distribution systems with DG. Simulation results on a modified Institute of Electrical and Electronics Engineers (IEEE) 4-node distribution system show that the proposed algorithm can perform adaptive relay coordination under various fault conditions. Compared with the conventional protection structure, relay coordination of adaptive protection scheme provides fast fault isolation and greater adaptation to different operating modes considering DG units.

A Classification Technique for Recloser-Fuse Coordination in Distribution Systems With Distributed Generation

In this paper, a novel approach is presented to study the impact of distributed-generation penetration on recloser-fuse coordination. The main core of this approach is based on an assessment process using a classification technique to classify the recloser-fuse coordination status at fault conditions to either coordination holds or coordination lost. Accordingly, the distribution system operator can take the proper decision. Then, two complementary actions are recommended in the proposed approach as a solution to decrease the number of cases where coordination is lost. The first one is to search for the best DG locations, where such locations are characterized by the minimum number of cases classified as coordination lost. The second one is based on changing the recloser setting in such a way to minimize the cases where coordination is lost. This new approach has been implemented on the IEEE 37-node test feeder using MATLAB-based developed software and the obtained results are presented and discussed.

Calculation of maximum DG’s capacity according to their location for remaining the protection coordination in distribution networks

Traditional electric distribution systems are radial in nature. These networks are protected by very simple protection devices such as over-current relays, fuses, and reclosers. Recent trends in distributed generation (DG) and its useful advantages perfectly can be achieved while the relevant concerns are deliberately taken into account. For example, penetration of DG disturbs the radial nature of conventional distribution networks. Therefore, protection coordination will be changed in some cases, and in some other cases it will be lost. In this paper, a new approach is presented for determining the maximum capacity of DG for maintaining the coordination of distribution system's protection devices. In the suggested approach, the contribution of DGs in fault current is limited through considering mathematical equations of characteristics of protection devices. All steps from the beginning to the end were implemented on a simple distribution network using MATLAB and DIgSILENT Power Factory and finally the numerical results are presented in order to confirm the authenticity of suggested approach.

Expert system for protection coordination of distribution system with distributed generators

Distributed or dispersed generation may cause various complexities to the operation of distribution system. Therefore, it is of interest to propose an expert system for protection coordination of distribution system under the presence of distributed generators. The expert system employs knowledge base and inference process to improve coordination settings of protective devices in order to accommodate the penetration of distributed generators. The expert system feeds input data by using graphical user interface and develops coordination settings based on power flow and short-circuit analyses. The expert system has been developed and successfully tested with a 22-kV distribution system with multiple distributed generations.

A Proposed Algorithm for Reactive Power & Voltage Coordination in Distribution Systems Using Fuzzy Technique

A Proposed Algorithm for Reactive Power & Voltage Coordination in Distribution Systems Using Fuzzy Technique

Islanding protection of active distribution networks with renewable distributed generators: A comprehensive survey

Anti-islanding protection schemes currently enforce the renewable distributed generators (RDGs) to disconnect immediately and stop generation for grid faults through loss of grid (LOG) protection system. This greatly reduces the benefits of RDG deployment. For preventing disconnection of RDGs during LOG, several islanding operation, control and protection schemes are being developed. Their main objectives are to detect LOG and disconnect the RDGs from the utility. This allows the RDGs to operate as power islands suitable for maintaining uninterruptible power supply to critical loads. A major challenge for the islanding operation and control schemes is the protection coordination of distribution systems with bi-directional flows of fault current. This is unlike the conventional overcurrent protection for radial systems with unidirectional flow of fault current. This paper presents a comprehensive survey of various islanding protection schemes that are being developed, tested and validated through extensive research activities across the globe. The present trends of research in islanding operation of RDGs are also detailed in this paper.