A review on protection issues in micro-grids embedded with distribution generations (original) (raw)
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Review of microgrid protection strategies: current status and future prospects
TELKOMNIKA Telecommunication Computing Electronics and Control, 2022
A microgrid is a developed form of a distribution system, which is integrated with a set of different types of distributed generation (DG) to supply local demand. In spite of that microgrids have many advantages as they increase reliability, raise efficiency, decrease feeder losses and voltage sag correction. However, there are many technical challenges faced, one of them is the protection of microgrid. Conventional protections have been made for radial distribution systems configuration. Where supplying source has one direction and the power flow is defined. The DG penetration converts the distribution network to a multi sources system causes a bidirectional power flow. Also, the most of DG uses a DC to AC converter which limit the fault current level. Therefore, a suitable protection scheme for microgrid ought to be designed to protect a microgrid from any disturbances may occur for both modes of operation grid-connected and islanded. The purpose of this paper is to summarize the challenges and problems facing microgrid protection. As well as the most strategies to date are presented with a discussion of their basic principles of operation to solve these problems. Finally, some conclusions and suggestions for microgrid protection in the future are presented.
Review on Microgrid and its Protection Strategies
International Journal of Renewable Energy Research, 2016
Microgrids are indispensable at the distribution level network and is capable of operating in both grid connected and islanded modes. Integration of renewable sources in a microgrid is a viable solution to provide continuity of supply to customers. Due to bidirectional power flow, conventional protection strategies are not applicable to microgrids. Also the change in topology of the network poses a key challenge to protection engineers. This paper reviews the advent of microgrid and also the protection strategies that are incorporated in the system integrated with renewable energy systems (RES).
The Power System and Microgrid Protection—A Review
Applied Sciences, 2020
In recent years, power grid infrastructures have been changing from a centralized power generation model to a paradigm where the generation capability is spread over an increasing number of small power stations relying on renewable energy sources. A microgrid is a local network including renewable and non-renewable energy sources as well as distributed loads. Microgrids can be operated in both grid-connected and islanded modes to fill the gap between the significant increase in demand and storage of electricity and transmission issues. Power electronics play an important role in microgrids due to the penetration of renewable energy sources. While microgrids have many benefits for power systems, they cause many challenges, especially in protection systems. This paper presents a comprehensive review of protection systems with the penetration of microgrids in the distribution network. The expansion of a microgrid affects the coordination and protection by a change in the current direct...
International Journal of Energy Research (IJER), WILEY, 2021
In the recent power system scenario, the concept of microgrid is evolving rapidly. The architecture should be robust enough to cater the complexity of integration of distributed generation sources, demand-side management, and storage. The fast growth of embedded generation with other advanced power electronic interfaces and components along with energy storage devices change the operating pattern of the integrated power system scenario. In this context, protection is the vital aspect for qualitative uninterrupted power and making the system resilient to adverse, and faulty conditions. Many associated issues, particularly related to AC microgrid systems like the large difference in the short-circuit level between integrated and isolated mode of operation, bidi-rectional power flow, unsynchronized reclosing, the blindness of protection, lack of natural zero-crossing current, and false tripping are needed to be focused. In light of the above factors, it motivates us to survey the previous research works on the existing protection strategies to redesign and present the critical analysis of the predicted protection issues of microgrid protection with upcoming advanced technology and methodology. This article presents a critical review of the issues and protection schemes for the DG integrated AC microgrid extensively. Here, the merits, and demerits of each protection scheme, and visible possibilities for any advancement in protection strategies to enhance the reliability, selectivity, and security of AC microgrid is emphasized keeping in mind the different connections and configurations. In addition , this work also focuses on integrating the intelligent approaches/devices that help to elevate the current protection schemes to be smarter and efficient.
Differential Protection of Microgrids with Central Protection Unit Support
Deployments of Distributed Generators (DGs) have large impacts on the structure of electrical networks. In order to tackle these issues, the `Microgrid` concept has been proposed However, due to their unprecedented structure, these smaller grids experience very significant protection issues. Conventional fault current protection schemes cannot be used and should be modified due to the existence of generators at all levels of the distribution system. Furthermore, two distinct operating modes (grid connected and islanded modes) exist in microgrids causing the fault currents in a system to vary substantially. It is also a challenge to operate Inverter Interfaced DGs (IIDGs) and estimate their fault currents. Consequently, differential current protection gains more attention for the microgrid protection. Differential protection is very versatile since it does not require prior knowledge of fault currents. The dynamic structure of the microgrids, ever-expanding networks and new deployments would require such a versatile protection. This paper presents a conceptual design of a protection system which employs a microgrid central protection unit (MCPU) to coordinate differential current protection. This system is also used to accommodate multi-terminal differential protection and propose a roll-back strategy, in case of communication failure. The proposed system is also compared with the differential protection from reliability perspective.
A Comprehensive Review of Protection Schemes for Distributed Generation
Due to the increasing demand of energy and the need for nonconventional energy sources, distributed generation (DG) has come into play. The trend of unidirectional power flow has been gradually shifting. With new technology comes new challenges, the introduction of DG into the conventional power system brings various challenges; one of the major challenges is system protection under DG sources. These sources pose a significant challenge due to bidirectional flows from DGs as well as lower fault current contribution from inverter interfaced DGs. This paper reviews existing protection schemes that have been suggested for active distribution networks. Most of these protection strategies apply only to smaller distribution systems implying that they may need to be extended to larger systems with a much higher penetration of distributed generation. In the end, a potential protection scheme has also been recommended as a future work.
Protection Coordination of Distribution System Equipped with Distributed Generations
Coordination among protective devices in distribution systems will be affected by adding distributed generators (DGs) to the existing network. That is attributed to the changes in power flow directions and fault currents magnitudes and directions due to the insertion of DG units in the distribution system, which may cause mis-coordination between protection devices. This paper presents an approach to overcome the impacts of DG units insertion on the protection system and to avoid the mis-coordination problem. The proposed approach depends on activating the directional protection feature which is available in most types of modern microprocessor-based reclosers. This will be accompanied by an updating of relays and reclosers settings to achieve the correct coordination. It's clear that this approach do not need any extra costs or any extra equipment to be installed in the distribution system. An existing 11 kV feeder, simulated on ETAP package, is used to prove the suitability and effectiveness of the proposed approach. The results ensure the possibility of achieving the proper coordination between protective devices after inserting DG units if the proper and suitable settings of these devices are realized.
Protection Coordination of Distribution Systems Equipped with Distributed Generations
Coordination among protective devices in distribution systems will be affected by adding distributed generators (DGs) to the existing network. That is attributed to the changes in power flow directions and fault currents magnitudes and directions due to the insertion of DG units in the distribution system, which may cause mis-coordination between protection devices. This paper presents an approach to overcome the impacts of DG units insertion on the protection system and to avoid the mis-coordination problem. The proposed approach depends on activating the directional protection feature which is available in most types of modern microprocessor-based reclosers. This will be accompanied by an updating of relays and reclosers settings to achieve the correct coordination. It's clear that this approach do not need any extra costs or any extra equipment to be installed in the distribution system. An existing 11 kV feeder, simulated on ETAP package, is used to prove the suitability and effectiveness of the proposed approach. The results ensure the possibility of achieving the proper coordination between protective devices after inserting DG units if the proper and suitable settings of these devices are realized.