Distribution System Protection 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.

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.

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.

Analysis of fault current contributions from small‐scale single‐phase photovoltaic inverters and their impacts on the protection of electric power distribution systems

AbstractThis paper presents an analysis of the fault current contributions of small‐scale single‐phase photovoltaic inverters under grid‐connected operation and their potential impact on the protection of distribution systems. To conduct this analysis, an autotransformer‐based voltage dip generator is proposed as a means to test the photovoltaic inverters' contribution to short‐circuit currents. Laboratory tests are then performed to obtain the short‐circuit current contribution of eight single‐phase photovoltaic inverters. Using the short‐circuit current data obtained, a behaviour model is developed and simulated on Matlab‐Simulink. The model is then applied to a real distribution system and case studies are conducted to simulate the potential impacts on the protection system. Results indicate that while the massive penetration of small‐scale single‐phase photovoltaic inverters can alter the protection system's operating time, the impacts are not significant. Only in very specific scenarios, such as events related to high impedance faults, some impact can be observed. In these situations, the presence of photovoltaic inverters further complicates the already difficult task of identifying high impedance faults through conventional overcurrent protections. This study provides valuable insights into the integration of photovoltaic inverters into distribution systems, and can aid in the development of effective protection measures for future grid designs.

Data Imputation Using Self Attention Based Model for Enhancing Distribution Grid Monitoring and Protection Systems

Data Imputation Using Self Attention Based Model for Enhancing Distribution Grid Monitoring and Protection Systems

Automated fault location scheme for low voltage smart distribution systems

AbstractIntegrating the self‐healing capability realizes the automated protection of smart distribution systems. This article presents a fault location scheme for low voltage (LV) distribution systems based on the information collected from the smart meters. First, a fault condition is detected and classified by processing the current signal at the secondary side of the distribution transformer by an intelligent electronic device. Then, the faulty feeder and section are determined by calculating the fault‐imposed component of nodal voltages. The reliable performance of the proposed scheme is verified through several case studies using a real semi‐rural distribution system.

Research on the Security Protection of Secondary Distribution System Based on Software defined Perimeters

<p>With the new technologies including big data, cloud computing, the Internet of Things (IoT), mobile Internet, and Artificial Intelligence (AI) coming into widespread in the secondary distribution system, it makes the network boundary more fuzzy, and the network security risk points and exposed surfaces significantly increase. Therefore, the traditional boundary-based security protection model has been unable to meet the protection needs. As one of the most popular security concepts at present, the zero trust mechanism can achieve the dynamic protection of information intranets. Based on the concept of zero trust security and software defined perimeter (SDP) technology, this paper designs and implements a security scheme suitable for the secondary distribution system and proposes a novel identity authentication model which can solve the problems of port exposure that existed in the traditional authentication scheme. In addition, the model applies the SM9 identification algorithm to reduce the computational cost of the encryption and decryption in the proposed scheme. Finally, the performance analysis demonstrates that the proposed scheme is effective and suitable for the secondary distribution system which can effectively resist multiple types of network attacks.</p> <p> </p>

Detection of Bad Data and Estimation of Missing Parameter Values Using System Synergism

Communication infrastructure is paramount for the optimal control and protection of modern-day distribution systems. However, inherent problems associated with the communication systems such as loss of data packets due to excessive latency and erroneous signal induction result in impairment of the network control and relaying signals. In the present article, a method based on Data Mining is proposed for the detection of Bad/Noisy data. Furthermore, the concept of system synergism is utilized to estimate the value of the signal in which Bad Data is detected. In case of Bad measurements during faults/ transients or load switching, the estimates are observed using Machine Learning (ML) based regression model. XGboost has been found to have the best performance among the ML models. Modbus is considered the communication protocol for the power distribution system under the consideration. Test results are demonstrated using a standard IEEE 33 bus test system. The feasibility of the proposed algorithm in real-time is confirmed using the raspberry pi 3B+ controller using Serial Peripheral Interface (SPI) protocol.

Examination of Gas Active Arc Extinguishing and Lightning Protection for Transmission Lines

The study investigated the gas active arc extinguishing and lightning protection for transmission lines. Lightning is one of the most significant sources of over voltages in overhead transmission lines. The lightning over voltages could lead to failure of the devices connected to the transmission line. Fundamental constraint on the reliability of an electrical power transmission system is the effectiveness of its protective system. The role of the protective system is to safeguard transmission system components from the effects of electrical overstress. Shield wire and surge arresters are an important means of lightning protection in transmission and distribution systems. Therefore, it is necessary to analyze the influence of over voltages caused due to lighting. The requirements of system security for lightning protection technology reach the high standard that lightning strike tripping and wire breakage are not allowed. Both the power supply side and the demand side have very high requirements for lightning protection of transmission lines, but the lightning accident rate remains high. This situation poses a great threat to the reliability and safety of power network, it is urgent to solve this problem. The gas active interrupter principle is put forward. From two latitudes of lightning overvoltage and power frequency over current, the effective control of lightning accident rate caused by large probability and multiple lightning strike is realized. This paper is aimed at evaluation of protection level of transmission line by using gas active arc extinguishing, shield wire and line surge arresters against lightning overvoltage. When lightning strikes, the internal short gap of the main body and the air gap break down, and the lightning arc enters the arc-extinguishing body through the breakdown channel. Arc is compressed by force to form internal and external gradients temperature in order to produce jet airflow. Jet airflow acts on the subsequent power frequency follow current arc, a model coupling an arc and a compressed jet airflow in a multi-fracture compression airflow arc-extinguishing structure is established and simulated. The increase in voltage due to lightning are investigated by using the MATLAB software. Direct and induced, types of lightning strokes are considered. The model of a 33kV three-phase overhead power transmission line is developed considering the RL circuit. The simulations are performed based on time domain analysis. Also, numerical analysis is made for 133kV tower structure transmitting power over 220km from 132 KV Sub-transmission Lines in port Harcourt region. Based on the simulation study this research study gas active arc extinguishing and lightning protection for transmission lines, are very important in computer application like Electromagnetic Transient Propagation (EMTP) and Power System Computer Aided Design (PSCAD) which are used in future study. These soft wares provide an alternative way to bring the precise result in study of lightning protection level of high voltage transmission line.

An Integrated Testbed for Power System Cyber-Physical Operations Training

The increased adoption of information and communication technology for smart grid applications will require innovative cyber–physical system (CPS) testbeds to support research and education in the field. Groundbreaking CPS testbeds with realistic and scalable platforms have progressively gained interest in recent years, with electric power flowing in the physical layer and information flowing in the network layer. However, CPSs are critical infrastructures and not designed for testing or direct training, as any misbehaving in an actual system operation could cause a catastrophic impact on its operation. Based on that, it is not easy to efficiently train professionals in CPSs. Aiming to support the advancement and encourage the training of industry professionals, this paper proposes and develops a complete testbed using a real-time simulator, protection and automation devices, and a supervisory control and data acquisition (SCADA) system. The testbed replicated the performance of smart grids, and the main potential cyber threats that electric grids may face. Different case scenarios include a distribution system protection study, a denial of service (DoS) attack, a jamming attack, a network packet manipulation attack, a sensor data manipulation attack, a false trip command attack, etc. The system’s performance before and after the cyberattacks are studied using packet-sniffing tools and a network packet analyzer. The impact on the grid is analyzed using metrics such as voltage oscillation, frequency deviation, and loss of active power generation. Moreover, the complex interdependencies between the cyber and physical domains are discussed in detail, providing insightful guidelines for key features and design decisions for future smart grid testbeds.

An Improved Arc Fault Location Method of DC Distribution System Based on EMD-SVD Decomposition

The influence of the control strategy of the power electronic converter obscures the fault characteristics of DC distribution networks. The existence of arc faults over an extended period of time poses a grave threat to the security of power grids and may result in electric shock, fire, and other catastrophes. In recent years, the method of fault localization based on the traveling wave method has been a popular topic of research in the field of DC distribution system protection. In this paper, the fault localization principle of the traveling wave method is described in depth, and the propagation characteristics of the traveling wave of fault current in the online mode network are deduced. We present a method for wave head calibration that combines empirical mode decomposition (EMD) and singular value decomposition (VMD). After the fault-traveling current signal has been subjected to EMD, the first eigenmode function is extracted and subjected to singular value decomposition (SVD). After SVD, the detail component can reflect the singularity of the signal. The point of the maximum value of the detail component signal corresponds to the moment when the faulty traveling wave head reaches the monitoring point. Finally, the DC distribution system is modeled based on the PSCAD/EMTDC simulation environment, and the fault location method is verified. The simulation results show that the method can effectively realize fault localization.

A Survey on the Application of Phasor Measurement Units to the Protection of Transmission and Smart Distribution Systems

Renewable energy resources have increasingly been integrated into electric power grids. Moreover, new challenges constantly arise, showing the need for modernization in monitoring, control, and protection. Transmission and distribution systems have explored the use of phasor measurement units (PMUs) in an attempt to meet these requirements. The decreasing cost of hardware components of PMUs, similar to what occurred with digital relays, is an important factor in terms of their worldwide use in different applications. Low-cost variations of PMUs focused on distribution systems, such as micro- and D-PMUs, are growing in number. Thus, this survey article presents significant and recent research conducted in the field of power systems using PMUs. Firstly, it briefly describes the characteristics of PMUs concerning hardware and phasor estimation algorithms. Afterward, recent studies related to transmission and distribution system protection based on PMUs are presented, such as fault detection and location, stability, and wide-area protection. Finally, the article also provided important guidelines, which certainly can be useful for future research in the years to come.

Roadmap to modernization of line protection in active distribution systems

The nature of distribution systems is changing from passive to active networks due to the integration of Distributed Energy Resources, especially Inverter-Based Distributed Generation (IBDG). This change presents challenges for existing fuse-based unidirectional protection schemes, as active networks experience bidirectional flow of power and small fault current contribution from IBDGs. Such fault behavior can impact the protection scheme’s sensitivity and selectivity, compromising the reliability of active distribution networks and leading to customer outages due to improper fault isolation. The problem is exacerbated in networks that allow the islanded mode of operation. Upgrading the entire protection system to microprocessor-based relays is expensive. Instead, this work proposes a planning strategy to optimally upgrade protective devices. The proposed framework is able to incorporate IBDG integration plans, distribution system reliability targets, protection requirements, and economic viability throughout the planning horizon. The obtained strategy determines the optimal number, location, and deployment time of protective devices in consideration of network characteristics. The developed optimization model is formulated as a Mixed-Integer Linear Programming problem. The results verify the proposed framework’s ability to economically upgrade the protection scheme while enhancing the reliability of the active distribution network with IBDGs.

Integrating IoT Technology for Improved Distribution Transformer Monitoring and Protection

Abstract This research study focuses on developing and implementing an IoT-based distribution transformer monitoring and protection system. The traditional methods of transformer protection and monitoring have proven to be inefficient and time-consuming, leading to the need for a more modern and effective solution. In this study, a low-cost prototype system is proposed to handle and control the main functions and problems of the distribution transformer through the internet. The proposed system allows for easy monitoring and protection of the transformer, enabling electric companies to improve efficiency and reduce labour and tool costs. The system is validated using Proteus software to simulate and obtain results from the hardware. The system results are displayed in multiple ways, including LCD, system bar, and internet, making it easier for electric companies and consumers in developing countries like Pakistan to monitor and control distribution transformers efficiently. This research study aims to provide valuable insights into the effectiveness of IoT-based distribution transformer monitoring and protection systems and their potential benefits in enhancing transformer performance and efficiency.

Optimal location of micro‐phasor measurement units in distribution system control, monitoring, and protection using hybrid technique

AbstractThis manuscript proposes a hybrid technique for the optimum location of micro‐phasor measurement units (μ‐PMUs) in the distribution system (DS).The proposed hybrid approach is the wrapper of dwarf mongoose optimizer (DMO) and pelican optimization algorithm (POA). The updating behavior of DMO is improved by the POA; therefore, it is called DMO‐POA approach. The main aim of the proposed approach is to avoid discontinuity of supply and minimizes the count of PMDs to reduce cost and attain the maximal count of measurement‐redundancy that is limited to full‐system observability for IEEE bus‐system in zero injection nodes (ZINs) and tie‐switches. The proposed approach considered the optimum count of μ‐PMUs is needed for the thorough distribution system economy, observability, and the reliability measure. The proposed approach considers the distribution of PMUs in the reconfiguration of smart‐distribution‐grids, ZINs and communication system requirements. Here, the objective‐function is aiming at minimizing the costs of reliability and capital. The proposed method uses the infrastructure of communication cost to simultaneously co‐optimize the system switching strategy and find the optimal sites for PMUs. The performance of the proposed technique is tested in different test‐systems, like IEEE‐14 bus, 13, 34, 37, and 123 buses and the performance is executed by comparing it with the existing approaches. Furthermore, the proposed system is effectual to find an optimal solution with less computation and decreases the complexity of the algorithm.

A Research on Modeling of High Impedance Fault Detection for Protection of Dc Distribution System

Abstract: High ohmic resistance faults area unit troublesome to find by standard overcurrent relays principally thanks to their low current magnitudes. This paper describes a model for representing high ohmic resistance faults in electrical distribution systems. The model is predicated in a very non-linear resistance representing the high ohmic resistance path throughout this sort of faults. Supported this model, the performance of many electrical variables associated to high ohmic resistance faults is analyzed and an algorithmic rule for top ohmic resistance fault detection in electrical distribution systems is given. Field activity and pc simulations validate the high ohmic resistance fault model and therefore the projected fault detection algorithmic rule. A high ohmic resistance fault (HIF) is generated once an energized conductor (of a primary feeder) makes contact with the bottom or with neighboring objects like branch trees, overgrown vegetation, building walls, asphalt, any object to ground. Such faults area unit undetectable by standard overcurrent devices like overcurrent relays and fuses as a result of their low current magnitude. What is more, arcing accompanies high ohmic resistance faults (hifs) and represents a risk of security to folks and injury to physical infrastructure. Thus, so as to get a trustworthy detection algorithmic rule, it's necessary to possess a reliable high ohmic resistance fault model. This paper presents an analysis of the HIF trial run results and a technique for modeling hifs by considering one nonlinear resistance to represent the fault.

Modified discrete Fourier transform algorithm for protection of shunt compensated distribution line

Introduction. The response time of the relay plays vital role when fault occurs on the line. Various algorithms are adopted to increase the sampling rate of the relay which, in turn, improves the response time. Methods. Discrete Fourier transform and modified discrete Fourier transform are the two algorithms used to calculate the fundamental frequency phasor of the signal required by the relay to initiate trip command. It is known that discrete Fourier transform takes four to five cycles to produce the fundamental frequency phasor but it fails to deal with the decaying DC component. On the other hand, modified discrete Fourier transform improves the response time by removing the decaying DC component along with the other harmonics in just one cycle and a few samples. The aim of this paper is to cover discrete Fourier transform and modified discrete Fourier transform algorithms to analyze the performance of the three overcurrent and one earth fault relaying scheme for different types of faults occurring in the distribution system. Methodology. The concept of three overcurrent and one earth fault scheme is also explained in this paper for protection of shunt-compensated distribution system. The scheme is designed for variable power factor. MATLAB/Simulink is used as the software tool to validate the results obtained for various types of faults occurring in the system. The results are represented graphically to illustrate the time of response of the protection scheme when shunt compensators are connected at the receiving end of distribution network.

Lightning Protection of Distribution Power Systems: Arrester Development and Application Over the Years

As the demand for higher quality power increases, the development of more lightning resistant distribution systems is required. This article is an overview of the challenges and opportunities we now face in the lightning protection of electric power distribution systems. Specific topics are lightning protection of underground circuits, overhead circuits, system equipment, and lines of all configurations.

Impacts of a Flux-coupling SFCL on the overcurrent protection for distribution system with infeed

With the rapid development of distribution system and the integration of distributed generations, the increasing fault current is threatening electrical equipment of the power grid. The superconducting fault current limiter (SFCL) is an effective solution to dealing with the large fault current in the distribution network. In this work, the characteristics of the current limiting impedance of the flux-coupling SFCL is presented. The impacts of the flux-coupling SFCL on the overcurrent protection for distribution system with and without infeed is analyzed. Furthermore, a simulation model of a real 10 kV distribution system with a flux-coupling SFCL is built to verify the analysis. This work is of significance to the coordination between a flux-coupling SFCL and the overcurrent protection for distribution system.

Ensemble models for circuit topology estimation, fault detection and classification in distribution systems

This paper presents a methodology for simultaneous fault detection, classification, and topology estimation for adaptive protection of distribution systems. The methodology estimates the probability of the occurrence of each one of these events by using a hybrid structure that combines three sub-systems, a convolutional neural network for topology estimation, a fault detection based on predictive residual analysis, and a standard support vector machine with probabilistic output for fault classification. The input to all these sub-systems is the local voltage and current measurements. A convolutional neural network uses these local measurements in the form of sequential data to extract features and estimate the topology conditions. The fault detector is constructed with a Bayesian stage (a multitask Gaussian process) that computes a predictive distribution (assumed to be Gaussian) of the residuals using the input. Since the distribution is known, these residuals can be transformed into a Standard distribution, whose values are then introduced into a one-class support vector machine. The structure allows using a one-class support vector machine without parameter cross-validation, so the fault detector is fully unsupervised. Finally, a support vector machine uses the input to perform the classification of the fault types. All three sub-systems can work in a parallel setup for both performance and computation efficiency. We test all three sub-systems included in the structure on a modified IEEE123 bus system, and we compare and evaluate the results with standard approaches.