Adaptive Overcurrent Protection 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.

Protection schemes for a battery energy storage system based microgrid

This paper evaluates directional and adaptive overcurrent protection schemes in microgrids. A microgrid supported by a centralised Battery Energy Storage System (BESS) is chosen for the study. The stringent PQ controller of BESS will not allow it to dissipate into a fault, during its charging mode, causing the conventional directional schemes to mal-operate. A direction estimation scheme using magnitude and angle of superimposed positive sequence impedance is proposed to address this issue in BESS. Further, two fault detection techniques are proposed for BESS integrated feeders. The Main Protection Unit (MPU) detects an internal fault when there is a mismatch in the direction of relays at either end of a feeder. The second scheme uses adaptive overcurrent relay settings. Since the fault current is limited with PQ control, the pickup current is calculated dynamically with this control. Whereas a fixed pickup current is chosen, when the BESS inverter is voltage controlled. Simulations have been carried out using MATLAB/SIMULINK software. The proposed schemes work well for bidirectional power flows and in grid connected and standalone modes of microgrid operation.

Adaptive Overcurrent Protection Applied to Power Systems with Distributed Generation and Active Network Management

Adaptive Overcurrent Protection Applied to Power Systems with Distributed Generation and Active Network Management

Adaptive Protection for Microgrid with Distributed Energy Resources

The microgrid includes a distribution system with low voltage, controllable load, and distributed energy resources (DER). The DERs have been increased in the recent power network to address global environmental concerns, which creates challenges in faults, synchronization, inertia control, etc. As the technologies are getting advanced day by day, the past technology becomes obsolete. The internet of things (IoT) and artificial intelligence (AI) are the most discussed topics to obtain solutions for the challenges. One of the proposed solutions is adaptive overcurrent protection, as it can be used for any grid. In this paper, an algorithm is developed for the adaptive overcurrent relay protection to overcome the challenges of the microgrid with distributed energy resources. Then, the solutions obtained from the adaptive overcurrent protection algorithm network simulation are compared to the traditional overcurrent protection algorithm using the four key points such as selectivity, reliability, sensitivity, and speed to have a good performance in the power network. All the simulation studies are done in the electrical transient analyzer program (ETAP) software environment. Simulation results validate the performance of the proposed algorithm for adaptive protection using the IEEE-9 bus system with a microgrid.

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.

An Adaptive Protection for Radial AC Microgrid Using IEC 61850 Communication Standard: Algorithm Proposal Using Offline Simulations

The IEC 61850 communication standard is getting popular for application in electric power substation automation. This paper focuses on the potential application of the IEC 61850 generic object-oriented substation event (GOOSE) protocol in the AC microgrid for adaptive protection. The focus of the paper is to utilize the existing low-voltage ride through characteristic of distributed generators (DGs) with a reactive power supply during faults and communication between intelligent electronic devices (IEDs) at different locations for adaptive overcurrent protection. The adaptive overcurrent IEDs detect the faults with two different preplanned settings groups: lower settings for the islanded mode and higher settings for the grid-connected mode considering limited fault contributions from the converter-based DGs. Setting groups are changed to lower values quickly using the circuit breaker status signal (XCBR) after loss-of-mains, loss-of-DG or islanding is detected. The methods of fault detection and isolation for two different kinds of communication-based IEDs (adaptive/nonadaptive) are explained for three-phase faults at two different locations. The communication-based IEDs take decisions in a decentralized manner, using information about the circuit breaker status, fault detection and current magnitude comparison signals obtained from other IEDs. However, the developed algorithm can also be implemented with the centralized system. An adaptive overcurrent protection algorithm was evaluated with PSCAD (Power Systems Computer Aided Design) simulations, and results were found to be effective for the considered fault cases.

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.

Optimized Adaptive Overcurrent Protection Using Hybridized Nature-Inspired Algorithm and Clustering in Microgrids

Microgrids have been popularized in the past decade because of their ability to add distributed generation into the classic distribution systems. Protection problems are among several other problems that need solutions in order to extract the full capability of these novel networks. This research follows the branches of two major solutions, namely adaptive protection and protection optimization. Adaptive protection implementation with a novel concept of clustering is considered, and protection setting optimization is done using a novel hybrid nature-inspired algorithm. Adaptive protection is utilized to cope with the topology variations, while optimization techniques are used to calculate the protection settings that provide faster fault clearances in coordination with backup protection. A modified IEEE 14 bus system is used as the test system. Validation was done for the fault clearing performance. The selected algorithm was effective than most other algorithms, and the clustering approach for adaptive overcurrent protection was able to reduce the number of relays’ setting groups.

An adaptive overcurrent protection system applied to distribution systems

In this paper, an innovative adaptive directional overcurrent protection system for electric power distribution systems with respect to distributed generation is proposed. The proposed system supervises network topology based on the monitoring functionality of numerical relays. The system detects any changes in the configuration and recalculates the directional overcurrent protection settings by using a microgenetic algorithm. The proposed system was evaluated for several operating scenarios and insertion levels of distributed generation, and then compared with both conventional and adaptive protection systems by means of a traditional genetic algorithm. The results showed that the performance of the proposed system is superior to the other two methods in terms of both speed and selectivity. This shows that this is a promising proposal for the protection of modern electric power distribution systems.

An Intelligent Adaptive Overcurrent Protection System for an Automated Microgrid in Islanded and Grid-Connected Operation Modes

As the penetration of distributed generation sources increases at the distribution level, the necessity of designing microgrids is highlighted. Microgrids can operate in either islanded (separated from the utility grid) or grid-connected mode. Apart from the technical and economic benefits of microgrids, they may cause some protection issues in distribution systems. The most important of these issues is the difference between the short circuit levels in islanded and grid-connected operation modes. In this paper, an intelligent overcurrent relay that can adapt to the microgrid operation mode is proposed; that is, the relay detects the microgrid operation mode by means of an adaptive algorithm. The proposed adaptive method optimizes the accuracy and speed of the algorithm for detecting the microgrid operation mode. Then, the optimal settings that have been already stored in the relay are activated according to the microgrid operation mode. All internal processes of the relay use the voltage and current sampled at the relay location. As a result, the relay can be used in all networks without communication infrastructures. Finally, the proposed method is implemented in a sample microgrid. The superiority of the intelligent relay performance over conventional overcurrent relays is shown by numerical results.

Method for identification of grid operating conditions for adaptive overcurrent protection during intentional islanding operation

Currently, it is considered that distributed synchronous generators may operate in intentional-islanding operation mode, in which a portion of the power grid, which consists of load and distributed generation, is isolated from the remainder of the utility system. However, the fault current level of the feeders drastically decreases when the utility grid is disconnected and the protection will not properly operate if the overcurrent settings are not changed. In this paper it is proposed a method for identification of the grid operating conditions, utility connected or islanded. The method is based on the use of a local scheme installed close to the protection device. The scheme uses a thyristor which is fired during a short waveform interval of voltage. The thyristor voltage and current are monitored and used to calculate the grid equivalent impedance. According to the grid equivalent impedance it is possible to determine whether the utility is connected or not. Simulations considering a distribution system and a distributed synchronous generator are used to validate the proposed method. The results show that the method can be used to update the protection settings when the operating condition of the system is changed from utility-connected to islanded operation mode or vice-versa. As a result, the method allows implementing an adaptive protection without the use of communication system or can be used as a backup to increase the resilience in case the communication is lost.

Morphological Fault Detector for Adaptive Overcurrent Protection in Distribution Networks With Increasing Photovoltaic Penetration

In this paper, a versatile and robust algorithm for overcurrent protection that is adaptive to the feeder PV penetration level as well as changing load condition in the distribution feeder is proposed. The algorithm has built-in dc-offset suppression capability as well as recursive least square error filter for current phasor estimation to provide input to the overcurrent fault detector. The proposed multistage morphological fault detector analyzes sudden change in fault current magnitude and its structure makes it convenient to update the fault threshold dynamically by measuring the current magnitude at regular interval, thus making the algorithm versatile and adaptive. The performance of the proposed algorithm is investigated by simulating different fault distances and fault types for increasing penetration levels of PVs on a simple radial distribution feeder .