Relay Placement Research Articles

Towards Enhancing Power System Protection in Distribution Systems with Distributed Generation: A Graph Theory-Based Systematic Relay Placement Approach

This manuscript presents an innovative approach to optimize power system protection through strategic relay placement in distribution systems with distributed generation (DG). Traditionally, distribution systems relied on radial configurations, assuming power flow from the grid feeder to downstream networks. However, with the integration of DG technologies, the complexity of relay placement and maintenance increases. The study aims to address protection system issues associated with connecting DGs, such as tripping of production units, blinding of protection, and undesirable islanding. The proposed methodology combines graph theory, energy not supplied (ENS) values, and relay coordination strategies to achieve reliable power system operation. The algorithm is implemented in MATLAB, utilizing data from DigSilent PowerFactory. The key constraints for relay placement, including islanding operation, relay coordination, and load priorities, are considered to minimize the number of power outages and increase overall system reliability. The effectiveness of the algorithm is demonstrated using IEEE 33-bus and 69-bus test systems under different conditions. Results show consistent and reliable relay placement locations, considering DG locations and load priorities. The algorithm's speed, effectiveness, and adaptability to different network topologies make it a promising approach for power system protection planning in distribution systems with distributed generation.

Optimization of Impedance Relay Placement in Medium-Voltage Electrical Distribution Systems through Clustering Algorithms and Metaheuristics

This study explores the feasibility of using impedance relays in electrical distribution systems, a context where their application is not as common as in transmission systems. Given the dynamic nature and complex topology of medium-voltage distribution systems, this work proposes an innovative methodology integrating clustering algorithms and metaheuristic techniques to optimize the placement of impedance relays and enhance system reliability and resilience. Using CYME simulation and the Ant Colony Optimization (ACO) method, case studies were designed to validate the effectiveness of the proposed methodology. The results demonstrated that strategic placement of impedance relays reduces failure frequency and significantly improves the system’s response to such failures. This approach allows for a more efficient configuration and quicker response, which is crucial for maintaining continuity and quality of power supply. A detailed analysis of system behavior under various fault scenarios illustrates the robustness and adaptability of the proposed solution, marking a significant advancement in the protection and optimization of electrical distribution systems.

Joint Optimization of Full-Duplex Relay Placement and Transmit Power for Multihop Ultraviolet Communications

Joint Optimization of Full-Duplex Relay Placement and Transmit Power for Multihop Ultraviolet Communications

FER-Restricted AUV-Relaying Data Collection in Underwater Acoustic Sensor Networks

Relaying is an effective method to achieve reliable and timely data collection, which is one of the most important parts of underwater acoustic sensor networks (UASNs). Considering that the relay position determines the reliability of relay communication, we study the problem of relay placement and place an autonomous underwater vehicle (AUV) to mobile relay data transmission and realize the reliable, low-latency, and low-energy data collection in UASNs. First, we formulate the relay positions that can meet a certain frame error rate (FER) requirement as the FER-restricted area (FRA), and approximate FRA with a three-dimensional geometry formula. The problem of reliable and timely data collection becomes planning a short AUV relaying trajectory under the FRA constraint. To this end, we propose a nearest-community (N-C) trajectory planning algorithm to design the AUV relay trajectory. A member grouping method and the necessity of position (NoP) concept are proposed to further reduce the relay positions and trajectory length of the AUV. Simulation results verify that the approximate FRA is more than 90% consistent with the real FRA and show that the N-C using NoP-based member grouping can successfully receive more packets per minute and consume fewer sensors’ energy than other algorithms.

A novel relay placement method for smart energy IoT systems in offices with genetic algorithm

<p>Smart energy in large offices and organizations is an important research area of the Internet of Things (IoT). The energy efficiency of buildings is vital for the environment and global sustainability. To achieve satisfactory performance for this goal, WiFi access point (AP) indoor coverage is of high importance. As it costs a lot to add more WiFi to have good coverage in all parts of the office’s buildings, we consider relay node (RN) instead of adding more APs. So in this paper, we propose a novel RN placement in order to improve the indoor coverage of offices considering the signal attenuation using a path-loss model as the main measure for determining positions. The main problem is the placement of these RNs and the required number of them by considering existing APs. At first, we obtain the radio propagation model parameters by considering the data that are collected from the AP. Then based on these parameters, the proposed solution uses a genetic algorithm (GA) for RN placement optimization problem. The experimental results display the effectiveness of the proposed solution for the RN placement problem.</p>

Protection coordination of DOCRs for different modes of microgrid operation

The present study is focussed on solving the relay coordination problem. Protection of microgrids is performed through the placement of directional overcurrent relays (DOCR). The efficacy of microgrid protection depends on coordination of all the DOCRs placed in the system. For this purpose, a number of optimization techniques have been employed by the power system researcher. In this paper, Grey Wolf Optimizer (GWO) is proposed for the protection coordination of DOCRs for different modes of microgrid operation. The proposed method is tested and validated on a 7-bus mesh system and a 9-bus radial test system. The proposed method has been compared with other meta-heuristic optimization approaches, namely Genetic Algorithm (GA), Artificial Bee Colony (ABC), Gravitational Search Algorithm (GSA), and Hybrid Particle Swarm Optimization Gravitational Search Algorithm (PSOGSA). Based on the obtained results, the GWO-based approach is very efficient in mitigating the problem of relay coordination as compared to other optimization techniques.

Online search for UAV relay placement for free-space optical communication under shadowing

Online search for UAV relay placement for free-space optical communication under shadowing

An assessment of different relay network topologies to improve Earth–Mars communications

The future of deep space communications encompasses a challenging situation where the current facilities used to communicate with different spacecraft may become saturated as a result of an increasing number of missions and their complexity. From this forecast, the present study intends to provide a solution to saturation problems through strategically-located upgradable relays for Earth–Mars communications. The foremost goal of this paper is to quantitatively uncover the potential enhancements coming from relay placement in strategic orbits between Earth and Mars. Herein, two relay configurations – a.k.a. network topologies – are analyzed: the Lagrange-relays network topology and a circular, homogeneously-distributed satellite constellation, acknowledged here as pearl constellation. The first uses the Earth–Sun system Lagrange points L3, L4 and L5 as potential locations for the relays, whilst the second defines an optimized orbit between Earth and Mars with 3 or 4 relay satellites.To aid in the analysis, the authors developed an open-sourced piece of software that obtains the link availability as well as the data rate at which two nodes may communicate, taking as a reference the Deep Space Network (DSN) for Earth, and the Mars Reconnaissance Orbiter for Mars. For complex topologies with more than two communicating nodes, the software outputs the end-to-end bit rate and optimal communication route at each time step. Moreover, this product is extensible to analyze and optimize any network topology and could be adapted to be used for contact management and mission planning in the future.The results show that the network-topology proposals are an advantageous option to significantly increase the link availability of Earth–Mars communications. Nevertheless, the Direct-To-Earth (DTE) link always outperforms the multi-hop path due to the limited telecommunication system’s capabilities of both the spacecraft and the relays. As a result of this, the study includes an analysis on the requirements of the relay’s design in order to make the constellation a beneficial and comparable alternative to the DTE link. This way, the proposed network topologies become a suitable option whom to share with the DSN communications workload, providing enhanced bit rates and data volumes as well as higher availability of the communication.

A Communication-less adaptive protection scheme for Self-Healing distribution systems

Network reconfiguration has allowed supply restoration to disrupted areas after fault events. However, changes in network topology can alter the direction and magnitude of fault currents and jeopardize the coordination of overcurrent relays. Adaptive protection schemes using system-wide communications have been developed to solve this issue by performing dynamic relay recalibration. Unfortunately, system-wide communications are also associated with huge economic costs, data integrity issues, and limitations of infrastructures. Moreover, in less developed communities, such schemes are less applicable. Although various communication-less schemes have been proposed, they mainly focused on adapting overcurrent relay protection for different distributed generation penetrations and microgrid islanding statuses. Currently, no communications-less adaptive protection method has been proposed to address the miscoordination of protection relays caused by network reconfiguration for supply restoration. Thus, this paper presents a communication-less adaptive protection scheme to maintain relay coordination in a reconfigurable distribution network that performs supply restoration. The scheme deploys microcontroller units to predict the correct relay settings by monitoring load flows through the relays. The scheme is demonstrated on the IEEE 33-bus and 69-bus test distribution systems using two different relay placement strategies, non-directional and directional relays. The proposed scheme achieved up to 10.8 times lower disruptions than the existing system in N-1–1 contingency scenarios. Overall, the scheme provides a simple and low-cost alternative to improve the effectiveness of power system protection in a reconfigurable network.© 2017 Elsevier Inc. All rights reserved.

Relay Placement for Maximum Flow Rate via Learning and Optimization Over Riemannian Manifolds

Relay Placement for Maximum Flow Rate via Learning and Optimization Over Riemannian Manifolds

On the Placement and Sustainability of Drone FSO Backhaul Relays

We consider free-space optical (FSO) communication links for the backhaul connectivity of small cells (SCs) where a UAV with an FSO apparatus can serve as a backhaul relay node. We demonstrate how such drone relay stations (DRSs) can be deployed in a high-rise urban area in order to provide FSO line-of-sight (LOS) links that are unobstructed by buildings. Also, in our solution we consider the case where solar panels are mounted on DRSs such that placing the DRS in a sunny location is prioritized, and we show the gain in terms of number of required trips to recharge the UAV.

Visible Light and Reconfigurable Intelligent Surfaces for Beyond 5G V2X Communication Networks at Road Intersections

Traffic safety at road intersections can be enhanced by improving opportunistic exchange of safety messages between vehicles. In urban intersection scenario, obstacles such as buildings and road side installations/signboards block the line-of-sight communication between vehicles. In order to enhance the reliability of communication link, the existing vehicular solution utilizes relay placement at road intersection. However, as the vehicular density increases, the existing vehicular-radio frequency (V-RF) communication with relaying tends to suffer from higher interference, lower packet reception rate, and longer communication delays due to channel congestion. In contrast to the existing solutions, we propose to use practical deployment strategies namely hybrid vehicular-visible light communication (V-VLC)/V-RF with relaying and reconfigurable intelligent surface (RIS) aided V-RF solutions to improve the communication range for urban vehicle-to-vehicle (V2V) communication. We present stochastic geometry based analytical framework to analyze the performance of proposed solutions in terms of outage probability, throughput and delay outage rate (DOR). Numerical results illustrate that the proposed solutions can achieve considerable performance improvement in outage, throughput while ensuring low latency as compared to conventional V-RF with relaying. These deployment strategies may also serve as a preferred alternative for Intelligent Transportation System (ITS) to meet ultra-high reliable and ultra-low latency communication for beyond 5 G (B5G) vehicular networks.

3D-multilayer magneto-inductive transceiver coil structure and optimal placement of relays for non-conventional media

3D-multilayer magneto-inductive transceiver coil structure and optimal placement of relays for non-conventional media

Fuzzy Logic-Based Energy-Optimal Collinear DF Relay Placement in Two-Hop $$\eta -\mu$$ Fading Channel

Fuzzy Logic-Based Energy-Optimal Collinear DF Relay Placement in Two-Hop $$\eta -\mu$$ Fading Channel

Empirical Comparison of Propagation Models for Relay-Based Networks in Urban Environments

We investigate propagation characteristics for wireless channels, applicable to Integrated Access and Backhaul (IAB) and relay-based networks with lamppost-height nodes at 5.5 GHz. We compare our empirical results with a variety of models that have been proposed for system simulation. Our work is based on an extensive measurement campaign in an urban environment, where we simultaneously measured base-relay, relay-mobile and base-mobile links. This simultaneity allows us to conclude that low-height relay nodes offer a minor path-loss advantage over the base-user link. Moreover, within the range of relay heights that we measured of 2.8 and 4.7 m, we observed no signi?cant gain associated with choosing the higher relay placement. Our results however also show that the base-relay link is quite stable over time and thus will lend itself to multi-antenna techniques requiring a small overhead in channel state information feedback. Our results add to the empirical data that the standards models are based on, providing path-loss results obtained simultaneously for all links of an urban relay-based system.

Relay Placement Algorithms for IoT Connectivity and Coverage in an Outdoor Heterogeneous Propagation Environment

A vast majority of the Internet of Things (IoT) devices will be connected in a topology where the edge-devices push data to a local gateway, which forwards the data to a cloud for further processing. In sizeable outdoor deployment regions, the edge-devices may experience poor connectivity due to their distant locations and limited transmission power. Repeaters or relays must be placed at a few locations to ensure reliable connectivity to either a gateway or another node in the network. A big challenge in achieving reliable connectivity and coverage is the outdoor propagation environment being heterogeneous. Engineers often deploy networks based on resource-intensive field visits, detailed surveys, measurements, initial test deployments, followed by fine-tuning. For scalability to large scale IoT deployments, automated network planning tools are essential. Such tools should predict connectivity based on the edge-device locations using available Geographical Information System (GIS) data, identify the need for relays/repeaters, and, if needed, suggest the number of relays needed with their locations. Furthermore, such tools should also be extended to suggest the minimum number and locations of base stations that maximise coverage. In this paper, we propose an automated network deployment framework using a black box received signal strength estimation oracle that provides signal strength estimates between candidate pairs of transceiver locations in a heterogeneous deployment region. Our proposed methodology uses either Ant Colony Optimisation (ACO) or Differential Evolution (DE) to identify the number and locations of relays for meeting specified quality of service constraints. We discuss adaptations of our techniques to handle scenarios with multiple gateways. Further, we show the effectiveness of these algorithms to find suitable candidate base station locations to provide coverage in a heterogeneous propagation environment that meets the specified quality of service constraints. We then demonstrate the effectiveness of our algorithms in two deployment regions.

An Efficent Coverage and Maximization of Network Lifetime in WSN Through Metaheuristics

<span>In wireless sensor networks (WSNs), energy, connectivity, and coverage are the three most important constraints for guaranteed data forwarding from every sensor node to the base station. Due to continuous sensing and transmission tasks, the sensor nodes deplete more quickly and hence they seek the help of data forwarding nodes, called relay nodes. However, for a given set of sensor nodes, finding optimal locations to place relay nodes is a very challenging problem. Moreover, from the earlier studies, the relay node placement is defined as a non-deterministic polynomial tree hard (NP-Hard) problem. To solve this problem, we propose a multi-objective firefly algorithm-based relay node placement (MOFF-RNP) to deploy an optimal number of relay nodes while considering connectivity, coverage, and energy constraints. To achieve network lifetime, this work adopted energy harvesting capabilities to the sensor nodes and backup relay strategy such that every sensor node is always connected to at least one relay to forward the data. The optimal relay placement is formulated as an objective function and MOFF is applied to achieve a better solution. Extensive Simulations are carried out over the proposed model to validate the performance and the obtained results are compared with state-of-art methods)</span>

Permanent Closed-Loop Operation as a Measure for Improving Power Supply Reliability in a Rural Medium Voltage Distribution Network

Power supply reliability is one of the critical elements of power quality. Its improvement in medium voltage distribution systems in urban areas is typically achieved by cabling. Unfortunately, this approach is often too expensive to be applied in rural areas. One of the possible alternative solutions that can be used in rural medium voltage distribution networks is permanent closed-loop operation. It requires the introduction of additional reclosers with properly parametrized protection relays enabling directional protection. This paper focuses on the case study performed in the 20 kV rural distribution network of Elektro Celje d.d.. Two feeders, where the reliability of the power supply was low, were analyzed. Results of techno-economical evaluation eliminated cabling as a viable solution. The permanent closed-loop operation was selected and implemented after proper placement and parameterization of relays with directional protection functions. The results of two years operation in permanent closedloop arrangement of feeders show substantial improvement in the reliability of power supply.

3D Urban UAV Relay Placement: Linear Complexity Algorithm and Analysis

Optimal unmanned aerial vehicle (UAV) placement in a 3-dimensional (3D) space to build a connection between a base station (BS) and a ground user is studied herein. A key challenge is to avoid signal propagation blockage due to obstacles. Much prior work uses probabilistic terrain models with model parameters learned from the statistics over a large area, and therefore, the optimization for a specific user in a small local area is poor. In contrast, this paper seeks the optimal UAV position over actual and fine-grained terrain, and develops efficient UAV positioning strategy adaptive to the degree of location-dependent line-of-sight (LOS) condition measured on the fly. It is proven that the globally optimal UAV position in 3D can be determined from the proposed search trajectory which has merely linear length in the diameter of the target area. Therefore, the proposed strategy can be practically implemented. Numerical experiments are performed over a real-world urban topology and demonstrate superior performance gain over existing strategies based on probabilistic models.

A new algorithm inspired by Impala Mexican Wave with variable stride for relay node placement as a nested reverse p-median problem in disjoint wireless sensor networks

In the wireless sensor network (WSN) environment, large-scale failure due to the explosion, energy depletion, harsh or hostile environments, can cause disjoint partitions and disconnect the network. In this case, relay nodes (RNs) can deploy to restore connectivity. This paper has proposed a new algorithm inspired by Impala Mexican Wave with variable stride (IMWVS) for relay placement. This method solves the nested reverse p-median problem. The purpose of this method is to reduce the number of deployed RNs and increase the robustness of the network. Also, the coverage and reliability of the method can be satisfied. In terms of the number of deployed RNs, IMWVS has 50.49 and 68.18% improvement averagely in comparison with CRP and RRLC-GBP methods for large-scale multiple partitions resulted from multiple failures, respectively.