Adaptive Overcurrent Protection Scheme Research Articles

Adaptive overcurrent protection scheme coordination in presence of distributed generation using radial basis neural network

The operational performance of conventional overcurrent protection relay coordination connected to a distribution network is adversely affected by the penetration of distributed generators (DG) at different buses in the network. To address this problem, this paper proposes a novel adaptive protection coordination scheme using a radial basis function neural network (RBFNN), which automatically adjusts the overcurrent relay settings, i.e., time setting multiplier (TSM) and plug setting multiplier (PSM) based on the penetration of DGs. Short circuit currents and voltages measured at different buses are acquired using the remote terminal units (RTU) connected to different buses within the terminal network. Communication between the various remotes and local end station RTUs is through hybrid communication systems of fiber optic and power line communication system modules. The new adaptive overcurrent protection scheme is applied to the IEEE 33-bus distribution network with and without DGs, for single and multi-DG penetration using both the ETAP and MATLAB software. The simulation results show the proposed scheme significantly improves the protection coordination.

Adaptive overcurrent protection scheme for distribution networks with connection of mobile energy storage devices

The increasing penetration of renewable energy sources in distribution networks has caused great challenges to the reliable operation of the conventional overcurrent protection schemes. In particularly, serious underreach and overreach problems of protection scope may occur under the ever growing application of mobile energy storage (MES) devices. To improve the adaptability to the connection of MES devices under distribution networks, this paper proposes an adaptive overcurrent protection scheme, which can avoid the unfavorable effects caused by infeed currents and out flowing currents. Firstly, the effects of MES device on the protection scope of the overcurrent protection strategy are investigated, considering the charging, discharging, and backup operation modes of MES device. Secondly, to adapt to the different operation modes, the equivalent impedance of MES device is calculated, and then it is introduced to determine the adaptive settings of fast current protection and time-critical fast current protection. Finally, the constructed adaptive overcurrent protection scheme can adapt to varied fault conditions, including different operation modes and output power of MES device, connection locations, fault locations, and fault types. Large amounts of simulation results show that the proposed adaptive overcurrent method can overcome the underreach and overreach problems of protection scope, demonstrating its good application prospects.

Adaptive overcurrent relay (AOCR) based on Fano Factors of current signals

AbstractA Fano Factor‐based adaptive overcurrent protection scheme, that automatically adjusts the protection settings in response to the prevailing conditions of the power system, is presented. Both phase and ground overcurrent relays are based on the same mathematical algorithm to calculate the operating time using Fano Factors (FFs) estimated for phase and ground current signals, respectively. Effectiveness of the proposed adaptive overcurrent method is validated for various fault types under a plethora of loading current levels, besides a wide range of fault inception angles and fault resistance. Simulation results confirm that the proposed algorithm can detect series and shunt faults, differentiate between grounding and phase faults, and adapt the relay operating time settings using the FF for all conditions examined. The relay algorithm speed and sensitivity are controllable using both the FF setting values and moving data window size. Moreover, it is characterized by being simple, reliable, accurate, and can be implemented practically as a base of digital protective relay for use in substation automation systems and phasor measurement units.

A dynamic hybrid protection scheme for on-site emergency power system operated through an integrated microgrid during station blackout in NPP

Post Fukushima nuclear disaster, application of renewable energy operated integrated microgrid (IMG) into nuclear power plants for strengthening the station blackout (SBO) power supply becomes popular. The IMG powered emergency-SBO (EM-SBO) is a bidirectional power system which leads to substantial variation in fault current. On the other hand, as per the guidelines of nuclear regulatory authority, minimum protection scheme is to be provided for EM-SBO power system to avoid unnecessary tripping of the safety power system. This scenario is a challenging task and a serious concern to provide suitable protection mechanism. To address this issue, a dynamic hybrid protection (DHP) scheme (hybrid differential and adaptive overcurrent protection scheme) is proposed. The proposed DHP scheme has been validated in EMTP-rv and DigSILENT Power Factory simulation software followed by harmonics analysis through Simulink. Finally, the superiority of DHP scheme for IMG has been established.

Adaptive Overcurrent Protection Scheme for Power Systems with High Penetration of Renewable Energy Recourses

Due to high penetration of renewable energy recourses in the existing distribution network, the protection system faced a new challenge. This paper presents an adaptive overcurrent protection scheme for active distribution network ADN enhanced by real time measurement gathered from micro phasor measurement unit 𝜇PMU. The 𝜇PMU measurement is used in this paper to estimate the network topology of the ADN. The proposed scheme has been tested and validated using MATLAB programing environment. The simulation results demonstrate the effectiveness of the proposed adaptive protection scheme.

Selectivity Problem in Adaptive Overcurrent Protection for Microgrid With Inverter-Based Distributed Generators (IBDG): Theoretical Investigation and HIL Verification

The advancements in smart grid technologies had brought forth the prospect of self-healing distribution grid through intentional islanding, aided by the steadily rising penetration of inverter-based distributed generations (IBDGs). Adaptive protection is the key enabler for this resilient grid architecture. For cost-effectiveness, overcurrent relays (OCRs) with adaptive features had been proposed, often with the sensitivity problem due to low short-circuit current magnitude from the IBDG taken into consideration and largely addressed. However, apart from this widely discussed sensitivity problem, there is an underlying issue on selectivity of the OCR which is frequently disregarded when designing an adaptive overcurrent protection scheme for IBDG dominated microgrid. This selectivity problem is mainly caused by the current diversion to load during fault, which is often disregarded when performing OCR grading for a conventional grid. In this paper, this selectivity problem of the OCR is discussed in depth through a comparative study of conventional grid and a modern IBDG dominated grid. The coordination time interval margin violations problems are demonstrated through theoretical calculations and real-time hardware-in-the-loop experiments. This research aims to provide better insights into the selectivity problem as a step towards achieving a cost-effective yet reliable overcurrent-based adaptive protection for IBDG dominated microgrid.

An Adaptive Overcurrent Protection Scheme for Dual-Setting Directional Recloser and Fuse Coordination in Unbalanced Distribution Networks With Distributed Generation

The recloser–fuse coordination of the distribution networks (DNs) equipped with distributed generators may be jeopardized by using the conventional overcurrent protection strategies thus degrading the network reliability. This article focuses on the design of a protection coordination strategy based on the dual-setting directional recloser (DSDR) for the effective implementation of a fuse-saving scheme in DNs. The proposed DSDR-based protection strategy will assist the network operators by providing a flexible coordination range along with more accurate protection settings to meet the protection coordination requirements. The performance of the proposed protection scheme has been validated through its implementation on IEEE standardized test systems and a comparative analysis has been drawn to demonstrate its effectiveness. Furthermore, this article concentrates on the economical design of the protection strategy for DNs by utilizing fewer numbers of protective devices. The results show that the proposed strategy will considerably reduce the number of temporary and sustained interruptions experienced by the consumers of large DNs thus improving the network reliability indices.

Development of a Communication-Assisted Adaptive Overcurrent Protection Scheme in Smart Distribution Networks in Presence of Wind and Solar Generation

Development of a Communication-Assisted Adaptive Overcurrent Protection Scheme in Smart Distribution Networks in Presence of Wind and Solar Generation

An Adaptive Overcurrent Coordination Scheme Withstanding Active Network Operations

This paper aims to present a centralized adaptive protection scheme (APS) for the directional overcurrent relays (DOCRs) considering system dynamics such as load demand variations, topology changes and DGs to mitigate the above-mentioned effects. The scheme is suitable for different types of networks whether its radial or meshed. Afterall, it can determine the actual topology with the micro-PMUs and breaker status, automatically generate relay names accordingly with the topology bus locations, establish protection coordination pairs, coordinate DOCRs for parallel lines, identify transformers to offer backup operation for differential protection, perform load flow and fault studies, execute contingency and sensitivity analysis, and lastly, coordinate the DOCRs using differential evolution algorithm so that they always have the proper settings to operate in appropriate time providing selectivity. The performance of the proposed centralized adaptive overcurrent protection scheme is tested on the highly meshed IEEE 14 bus system. The proposed scheme has shown that it can adequately consider impacts of system dynamics and DG.

Adaptive overcurrent protection scheme suitable for station blackout power supply of nuclear power plant operated through an integrated microgrid

Inclusion of distributed energy resources based integrated microgrid (IMG) into emergency station blackout (SBO) (EM-SBO) power system of nuclear power plant (NPP) has complicated its existing protection scheme due to varying system fault level with bidirectional flow of power. During SBO in NPP, it is of topmost priority to safeguard the reactor through EM-SBO supply. However, if any severe fault occurs, it may lead to complete collapse of the safety power supply in the NPP. So, availability of this tiny power system is most important as compared to the tripping of reactor safety of the NPP. In this paper, a 460 MWe NPP station has been considered to implement IMG into its EM-SBO power system and focuses on its overcurrent protection coordination scheme as a case study. The combined fuse and numerical relays inter-linked with digital logic-based adaptive overcurrent protection (AOP) scheme has been proposed after load flow analysis and calculating short circuit fault level through ETAP software. The sensitivity, the selectivity and the speed of the protection scheme have been evaluated in different network configurations like on-grid, semi-islanding and islanding mode of operation of IMG. Finally, it is proposed that the protection schemes vary from case-to-case basis leading to necessity of communication among the relays. So, an advanced AOP scheme with digital logic linked through peer-to-peer Hi-speed communication (IEC 61,850 confirmed GOOSE technology) has been proposed to resolve the protection issue of the modern NPPs operated through IMG.

A review of adaptive overcurrent protection in distribution networks with integration of distributed energy resources

This paper presents a review of an adaptive overcurrent protection scheme in a distribution network with the integration of distributed energy resources. The rapid integration of distributed energy resources brings challenges to the existing overcurrent protection system. The impacts are change in fault current magnitude and direction of current flow from radial to the multi-source dynamic network, which causes changes in network topology, inaccurate fault detection, and loss of coordination among protection systems. In this paper, the solution identified for reliable operation of overcurrent protection in the distribution network are network topology estimation, fault detection, and adaptive coordination.

Design of an adaptive overcurrent protection scheme for microgrids

Microgrid is a new phenomenon regarded to Distributed Generation (DG) penetration in the existing distribution systems. In this paper adaptive over current (OC) protection technique for a distribution system with DG penetration is proposed. This scheme takes into account general protection requirements, impacts of DG on protection system and protection coordination. A part of IEEE 13 nodes radial distribution test feeder is taken as a study case to test the effectiveness of the proposed scheme using ETAP software.Keywords: Distributed Generator, Microgrids, Adaptive overcurrent protection, Protection Coordination

Fuse relay adaptive overcurrent protection scheme for microgrid with distributed generators

Utilities have installed distributed generators to improve reliability of the power distribution system. Distributed generators at various sites provide additional circuit paths in case energy provision to the end user is interrupted by a blackout or equipment failure. When the microgrid is working on island and grid-connected modes, overcurrent protections in power lines must be adjusted to different distributed generator circuit paths and feeder fuses in the microgrid. This study presents an adaptive overcurrent protection that integrates technical and economic advantages of fuses and relays in a microgrid with distributed generators. This fuse relay adaptive overcurrent protection (FRAOP) scheme protects power lines and feeders by grouping identical inverse time overcurrent settings of relays, and logic gates of relay's breakers. Selectivity, reliability, and speed of the FRAOP was verified by a real-time simulator with relays in-the-loop.

Communication-based Adaptive Protection for Distribution Systems Penetrated with Distributed Generators

In this article, a communication-based adaptive over-current protection scheme for distribution systems penetrated with distributed generators is proposed. A communication network between the over-current relays, the distributed generators, and the utility grid is employed to automatically update the settings of the protective relays. Moreover, the communication reliability is increased through the addition of a backup communication system. The proposed scheme has the advantage of operating during grid-connected and islanding modes of operation. The scheme employs two simultaneous algorithms. The first algorithm works when the system configuration is changed due to the connection/disconnection of a distributed generator or the utility grid. The second algorithm efficiently uses the exchanged information between the relays to identify the faulted section and hence speeds up fault clearance. The proposed scheme is tested for difierent fault conditions as well as for different system configurations. The results demonstrated that relay operating times, including the communication delay, are greatly reduced when the faulted section is identified and relay settings are adjusted accordingly. In addition, a negligible time delay was experienced when the backup communication network was put in service.

An Adaptive overcurrent Protection Scheme for Distribution Networks Including DG Using Distribution Automation System and its Implementation on a Real Distribution Network

Recently, a great attention has been paid in applying Distributed Generation (DG) throughout electric distribution systems. Although DG has many advantages and benefits, it has to be applied after performing detailed investigations due to their complexities in operation, control and protection of network. One of the most considerable problems that arise, when DGs are used, is destructing efficiency and qualification of the existing protection system. The injected currents of DGs to a distribution network lead to not having a radial network anymore, and consequently network faces an inefficient protection system that was formerly designed according to the existing philosophy behind the distribution network. In this paper, a new protection scheme has been presented to provide the distribution networks including DGs. The new approach, designed based on capabilities of Distribution Automation System (DAS), has been implemented using a computer-based relay which is installed in the sub-transmission substation. The proposed scheme has been implemented on some part of a real distribution network in Shiraz which is a large city in Iran and performance of the proposed scheme is tested on it. For simulating the distribution network and for implementing the relay algorithm, DIgSILENT Power Factory 13.2 and MATLAB are used respectively.

An adaptive overcurrent protection scheme for distribution networks including DG using distribution automation system and its implementation on a real distribution network

An adaptive overcurrent protection scheme for distribution networks including DG using distribution automation system and its implementation on a real distribution network