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Islanding classification and low-voltage ride through for grid connected transformerless inverter
Published in Rajesh Singh, Anita Gehlot, Intelligent Circuits and Systems, 2021
Mohammed Ali Khan, V.S. Bharath Kurukuru, Ahteshamul Haque
Islanding is generally classified into intentional islanding and unintentional islanding. Intentional islanding is the islanding event initiated on purpose during, e.g., a system disturbance (Khamis et al. 2013). Intentional islanding can ensure a reliable power supply for critical loads if well designed (Balaguer et al. 2011). During a sudden power outage case, if several DG units are out of step from each other, it’s better to form intentional islanding in the place where the mismatch of power between load and generation is minimum (Noor, Arumugam, and Vaziri, n.d.). In contrast, unintentional islanding is an islanding event which is not expected. Since it is not supposed to happen, the formation of unintentional islanding can cause unexpected personnel electric shock, because people are likely to touch the line which is supposed not to have electricity but can be powered due to islanding. Also, the severe consequences include electrical device damage and for the uncontrolled voltage and frequency operation many islanding detection techniques have been established, and they can be categorized into local and remote detection methods, out of which local methods can be further classified as active, passive and hybrid methods.
Design of Microgrids
Published in Sasi K. Kottayil, Smart Microgrids, 2020
Islanding is a condition in an electrical network in which one or more of generating sources and loads get isolated from the main grid or utility. Islanding happens when the grid disconnects at the PCC of a microgrid and the local generators of the latter continue to supply power to the local loads and form an electrical island. The grid disconnection may happen due to one or a combination of the reasons described below: A grid fault identified by the utility protection devices that initiated a disconnection,An equipment failure initiated opening of grid supply,An intentional shut down of the utility for network maintenance, orNatural calamities disrupted the network.
Protection of Renewable Distributed Generation System
Published in Ramesh Bansal, Power System Protection in Smart Grid Environment, 2019
Rishabh Dev Shukla, Ramesh K. Tripathi, Padmanabh Thakur, Ramesh Bansal
Anti-islanding is defined as a feature of a grid tie converter/inverter that identifies the occurrence of a power outage and shuts itself down to stop electricity production. It is an essential requirement of the UL1741/IEEE1547 when the grid enters an islanded situation. The RDGs/DGs must identify islanding and instantly stop power feeding to the utility lines. Islanding is a condition in which a distribution system becomes electrically isolated from the rest of the power system and continues to be energized by the DG associated with it. At present, islanding is taken as a most important problem and all DGs need to shut down while a distribution system is islanded. According to the IEEE 1547-2003 standard, the DG is to be disconnected within 2 seconds of the detection of islanding [30]. Per the IEC 61727 standard, detection of the islanding and disconnection of DGs must be within 2 seconds [31]. The main reasons for avoiding islanding operation are: change in fault power level [32], reclosing when out of phase [33], voltage and frequency control [32], safety of line workers, need of proper grounding [19], etc. Numerous detection techniques for islanding have been developed [34,35].
Islanding Detection System for Grid Connected Photovoltaic System under Different Fault Condition Using Intelligent Detection Method (IDM)
Published in Electric Power Components and Systems, 2023
R. Jai Ganesh, S. Muralidharan
Approaches for passive islanding detection method use modifications in the electrical characteristics to determine if an islanding operation has taken place or not. The harmonic contained detection approach, voltage amplitude detection techniques, system frequency detection technique are a few examples of islanding detection techniques on passive system. The harmonics, frequency, voltage and phase angle are among the system characteristics that are monitored at the distribution generation terminal or PCC. Whenever the output power of the grid linked inverter is about equivalent to the power needed by the loads in local, a power balance is produced. As a result, the localized load voltage does not significantly vary throughout the islanding operation in terms of amplitude or frequency. During the “non-detection zone” be the situation in which various passive detection technologies are unable to pick up the islanding activity. Consequently, the passive islanding detection techniques fall short of islanding management standards. Figure 3 shows the flow chart for passive island detection.
Review of islanding detection schemes for utility interactive solar photovoltaic systems
Published in International Journal of Green Energy, 2022
Nikita Gupta, Rahul Dogra, Rachana Garg, Parmod Kumar
Islanding is a situation in which a portion of the utility system, comprising both load and distributed resources, remains energized even if disconnected from the rest of the utility system (IEEE 2005)-(DIN VDE 0126, 1999)(already DIN VDE 0126:1999 referred here). The islanding can be intentional or unintentional. IEEE defines both intentional and unintentional islanding. Intentional islanding may be desirable in some cases, such as in a microgrid designed to run independently during a weather event or unforeseen outage. Unintentional islanding is not intended and is considered unwanted as the grid loses control over the electrical parameters of the islanded region under this condition. This may result in excursion of voltage or frequency causing problems in terms of power efficiency, harm to customer equipment and even risks staff personnel to hazardous environment. Therefore, islanding must be observed at the earliest, and the DG device in the islanded region must be disconnected from the rest of the system by shutting down the interface inverter as soon as possible. Xu, Mauch, and Martel (2004)-(Generation 2012) (Please refer (Budhraja, V. 2000) here)(Please refer Hoke, A. 2016 here)present the reports that describe the various methods and circuits developed to detect an islanding condition for real-world photovoltaic applications. They also present the schemes that have been developed to test those methods and circuits.
Back-Up Protection Scheme for Series-Compensated Transmission Line Connected to Wind Farm
Published in IETE Journal of Research, 2022
Islanding occurs when a load of a large distribution system loses grid power and is exclusively fed by the DG system i.e. the load is electrically secluded from the grid. When this happens, the system voltage and frequency are no longer within control, which implies that they may be over their normal limits, inflicting substantial and catastrophic damage to the equipment, devices, and gadgets linked to the system. The proposed scheme has been implemented for faults at various positions of the TL under varying FR, FIA, and compensation levels in the islanding mode of operation. The results of SLGA faults have been presented in Table 8, demonstrating the satisfactory performance of the proposed scheme under the islanding mode of operation.