Overcurrent relays coordination optimisation methods in distribution systems for microgrids: a review

Electric power networks connected with multiple distributed generations (microgrids) require adequate protection coordination. In this paper, the overcurrent relay coordination concept in distribution system has been presented with details. In this available literature, the previous works on optimisation methods utilised for the coordination of over current relays; classification has been made based on the optimisation techniques, non-standard characteristics, new constraints that have been proposed for optimal coordination and dual setting protection schemes. Then a comprehensive review has been done on optimisation techniques including the conventional methods, heuristic and hybrid methods and the relevant issues have been addressed

A review of networked microgrid protection: Architectures, challenges, solutions, and future trends

The design and selection of advanced protection schemes have become essential for the reliable and secure operation of networked microgrids. Various protection schemes that allow the correct operation of microgrids have been proposed for individual systems in different topologies and connections. Nevertheless, the protection schemes for networked microgrids are still in development, and further research is required to design and operate advanced protection in interconnected systems. The interconnection of these microgrids in different nodes with various interconnection technologies increases the fault occurrence and complicates the protection operation. This paper aims to point out the challenges in developing protection for networked microgrids, potential solutions, and research areas that need to be addressed for their development. First, this article presents a systematic analysis of the different microgrid clusters proposed since 2016, including several architectures of networked microgrids, operation modes, components, and utilization of renewable sources, which have not been widely explored in previous review papers. Second, the paper presents a discussion on the protection systems currently available for microgrid clusters, current challenges, and solutions that have been proposed for these systems. Finally, it discusses the trend of protection schemes in networked microgrids and presents some conclusions related to implementation

AC Microgrids Protection : A Digital Coordinated Adaptive Scheme

A significant challenge for designing a coordinated and effective protection architecture of a microgrid (MG) is the aim of an efficient, reliable, and fast protection scheme for both the grid-connected and islanded modes of operation. To this end, bidirectional power flow, varying short-circuit power, low voltage ride-through (LVRT) capability, and the plug-and-play characteristics of distributed generation units (DGUs), which are key issues in a MG system must be considered; otherwise, a mal-operation of protection devices (PDs) may occur. In this sense, a conventional protection system with a single threshold/setting may not be able to fully protect an MG system. To tackle this challenge, this work presents a comprehensive coordinated adaptive protection scheme for AC MGs that can tune their protection setting according to the system states and the operation mode, and is able to switch the PDs’ setting. In the first step of the proposed adaptive algorithm, an offline setting will be adopted for selective and sensitive fault detection, isolation, and coordination among proposed protective modules. As any change in the system is detected by the proposed algorithm in the online step, a new set of setting for proposed modules will be performed to adapt the settings accordingly. In this way, a new set of settings are adapted to maintain a fast and reliable operation, which covers selective, sensitive, and adaptive requirements. The pickup current (Ip) and time multiple settings (TMS) of directional over-current relays (DOCR), as well as coordinated time delays for the proposed protection scheme for both of the grid-connected and islanded modes of operation, are calculated offline. Then, an online adaptive protection scheme is proposed to detect different fault types in different locations. The simulation results show that the proposed method provides a coordinated reliable solution, which can detect and isolate fault conditions in a fast, selective and coordinated adaptive pattern.© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).This research was funded by the Department of Energy Technology, Aalborg University, under the Villum Investigator Grant 25920 as a part of the Villum Investigator Program CROM funded by the Villum Foundation.fi=vertaisarvioitu|en=peerReviewed

Impact of distributed generation on protection and voltage regulation of distribution systems : a review

During recent decades with the power system restructuring process, centralized energy sources are being replaced with decentralized ones. This phenomenon has resulted in a novel concept in electric power systems, particularly in distribution systems, known as Distributed Generation (DG). On one hand, utilizing DG is important for secure power generation and reducing power losses. On the other hand, widespread use of such technologies introduces new challenges to power systems such as their optimal location, protection devices' settings, voltage regulation, and Power Quality (PQ) issues. Another key point which needs to be considered relates to specific DG technologies based on Renewable Energy Sources (RESs), such as wind and solar, due to their uncertain power generation. In this regard, this paper provides a comprehensive review of different types of DG and investigates the newly emerging challenges arising in the presence of DG in electrical grids.fi=vertaisarvioitu|en=peerReviewed

Protection of multi-inverter based microgrid using phase angle trajectory

This thesis presents a simple, yet a clever way of using the current phase angle to develop low bandwidth communication-assisted line protection strategies for medium and low voltage AC microgrids, particularly those with multi-inverter interfaced distributed generators. It is now a trend in both AC transmission and distribution segments of power network that inverters interface renewable energy to the system. Unlike synchronous generators the fault feeding, and control characteristic of these generators are different and mostly influenced by the topology, switching, control deployed in the power electronics interface. The limited and controlled fault current challenges the existing conventional protection schemes. Offering higher power supply reliability and system resilience than conventional radial distribution systems, multi-inverter based microgrids, particularly those with loop and mesh typologies, are characterised by bidirectional power flow. This further constrains traditional protections such that communication-less protection schemes become ineffective for such systems. So unit protection types, such as differential protection, become more technically suitable for such microgrids despite the necessity for a communication system. In this thesis, two current direction based protection schemes for medium voltage islanded microgrids have been developed. The change in current flow direction in a line is detected using the cosine of the positive sequence current phase angle. Expressing the change and no-change of the flow directions as binary states, a low bandwidth communication based protection scheme is proposed comparing the binary states from local and remote ends of the line. To further enhance the scope and reliability of this scheme, a second protection scheme is proposed in Chapter 7 whereby the cosine function is combined with the rate of change of the slope of the phase angle (ROCOSP). This combination allows the detection and isolation of a fault even with the failure of the communication channel between relays protecting a faulted line. Furthermore, these scheme can work together and share the communication infrastructure as primary and backup protections. The performance of these schemes was assessed through simulations of microgrid models developed in Matlab/Simulink.Open Acces

The Coordination Of Dual Setting Directional Overcurrent Relay In PT. Pupuk Sriwidjaja Ring System Using Adaptive Modified Firefly Algorithm

Directional Overcurrent Relays (DOCRs) play an essential role in the power system protection to guarantee the reliability, speed of relay operation and avoiding mal-trip in the primary and backup relays when unintentional fault conditions occur in the system. Moreover, the dual setting protection scheme is more efficient protection schemes for offering fast response protection and providing flexibility in the coordination of relay. The Adaptive Modified Firefly Algorithm (AMFA) is used to determine the optimal coordination of dual setting DOCRs in the ring distribution system. The AMFA is completed by choosing the minimum value of the pickup current (Ip) and time dial setting (TDS). On the other hand, dual setting DOCRs protection scheme also proposed for operating in both forward and reverse directions that consisted of individual time current characteristics (TCC) curve for each direction. The AMFA method is applied to the ring distribution system network of PT. Pupuk Sriwidjaja by considering the fault on each bus. Then, the result is illustrated that the AMFA within dual setting protection scheme is significantly reaching the optimized coordination and the relay coordination is certain for all simulation scenarios with the minimum value of the total operating time (TOP). The CTI of each pairs relay is no less than 0.2s. Also, the comparison of converges iteration shown that the AMFA method is faster than the original FA method. The AMFA has been successfully implemented in MATLAB 2018b software and the relay coordination can be verified by using ETAP 12.6.0. ================================================================================================================================ Directional Overcurrent Relays (DOCRs) memainkan peran penting dalam perlindungan sistem tenaga untuk menjamin keandalan, kecepatan operasi rele dan menghindari mal-trip pada rele primer dan cadangan saat kondisi gangguan yang tidak disengaja terjadi dalam system. Selain itu, skema perlindungan pengaturan ganda adalah skema perlindungan yang lebih efisien untuk menawarkan perlindungan respons cepat dan memberikan fleksibilitas dalam koordinasi rele. Algoritma Adaptive Modified Firefly (AMFA) digunakan untuk menentukan koordinasi optimal DOCRs dalam sistem distribusi cincin. AMFA diselesaikan dengan memilih nilai minimum Pickup Current (Ip) dan Time Dial Setting (TDS). Di sisi lain, skema perlindungan DOCR juga diusulkan untuk beroperasi di arah maju dan mundur yang terdiri dari kurva individu Time Current Characteristics (TCC) untuk setiap arah. Metode AMFA diterapkan pada jaringan sistem distribusi cincin PT. Pupuk Sriwidjaja dengan mempertimbangkan kesalahan pada setiap bus. Kemudian, hasilnya diilustrasikan bahwa AMFA dalam skema perlindungan pengaturan ganda secara signifikan mencapai koordinasi optimal dan koordinasi rele pasti untuk semua skenario simulasi dengan nilai minimum Total Operating Time (TOP). CTI dari masing-masing pasangan relay tidak kurang dari 0,2s. Juga, perbandingan iterasi konvergen menunjukkan bahwa metode AMFA lebih cepat daripada metode FA asli. AMFA telah berhasil diimplementasikan dalam perangkat lunak MATLAB 2018b dan koordinasi rele dapat diverifikasi dengan menggunakan ETAP 12.6.0

Implementation of Interlocking Scheme for Bus bar and Arc Protection Using IEC 61850

The main scope of the thesis is to focus on bus bar protection in the medium voltage level. It is important for designing the protection setup according to the intended protection scheme, planning for circumvent the arc fault and set up the protecting device in a required manner. In this thesis there are different protection schemes for the bus bar have studied. The arc incident has discussed and put emphasis on the process of arc development. For mitigating the arc faults and other unwanted fault incident, it is important to have a co-ordination between the protecting devices. IEC 61850 is an important protocol of communication that has discussed from the basic idea. In the thesis it has given effort on the implementation of bus bar protection scheme with the protection devices in the substation. Those devices are communicating with each other for exchanging the GOOSE message using IEC 61850. The protection devices are connected with arc sensor and getting the input signal from it. A proposed design scenario has implemented with different fault situation in different location. The thesis has given the idea about the protection scheme of bus bar implementation in a medium voltage substation perspective. It is also helps to understand how the protection devices are working and communicating with each other via GOOSE message. The thesis is also able to demonstrate the role of protection scheme on the bus bar and the co-ordination of protective devices for implementation of the scheme. It has also ability to accommodate the arc flash sensor which increases the protection sensitivity

Impact of Combined Heat and Power Generation on an Industrial Site Distribution Network

Presence of Distributed Generation (DG) in Industrial Site Distribution Network (ISDN) can represent a significant impact on the operational characteristics of the network. Present planning and operation criteria use for ISDN are in general not suitable to cope with the presence of a significant DG capacity. The presence of DG provides considerable benefits from both engineering and economic viewpoints. However, it changes radial configurations of the distribution feeders. Consequently it may cause coordination failure to existing protection system which is originally set based on radial configuration. In addition, high penetration of DG into ISDN may increase feeder loss, and cause system voltage profile out of a required range. Distributed Generation may have a significant impact on the system and equipment operation in terms of steady state operation, dynamic operation, reliability, power quality, stability and safety for both ISDN user and electricity suppliers. The idea behind the connection of DG is to increase the reliability of power supplied to the customers, make use of a locally available resource and, if possible, reduce losses in transmission and distribution systems. The specific benefits depends on the local conditions and installation owner’s interest. The reasons for installing DG at ISDN include: i) Combined Heat and Power Plant (CHP) – High Efficiency ii) Standby/emergency generation-enhanced reliability The effect of the DG units on these quantities strongly depends on the type of DG units and the type of ISDN. DG units can be either directly connected to the ISDN, such as synchronous or asynchronous generators, or via a power electronics converter. In all these cases, the power flow in the ISDN as well as the network losses and the voltage control are affected. The introduction of DG alters the characteristics of the network. The number of technical constraints and factors are impacted by the amount of DG that is connected