Fig 1 - uploaded by Dimitrios Tzelepis
Content may be subject to copyright.
Source publication
![Fig. 2 Protection using travelling waves [75]](profile/Dimitrios-Tzelepis/publication/318673682/figure/fig2/AS:631667605651506@1527612701920/Protection-using-travelling-waves-75_Q320.jpg)
Hybrid microgrids which consist of AC and DC subgrids interconnected by power electronic
interfaces have attracted much attention in recent years. They not only can integrate the main benefits of both
AC and DC configurations, but also can reduce the number of converters in connection of Distributed
Generation (DG) sources, Energy Storage Systems (...
Context in source publication
Context 1
... structure is designed to combine the merits of both AC and DC microgrids. The structure includes two independent AC and DC subgrids, each consists of their own DG sources, ESSs and loads; also, in order to avoid the power losses during conversion process, the power transfer between the two subgrids is minimised [18,19]. The task of interfacing converter is to import/export active power to/from DC subgrid, and to provide reactive power to AC subgrid. The architecture of a typical hybrid AC/DC microgrid is shown in Fig. ...
Similar publications
Nowadays, the infrastructure and technologies in conventional distribution networks (CDNs) limit its further development to smart distribution networks. One way to overcome this is to develop CDNs using interconnected virtual microgrids (VMs); however, there is no consensus for an explicit definition of VMs. Therefore, in this paper, a comprehensiv...
With the changing scenario of technical impacts and increasing awareness of renewable generation, there is a trend to utilize the resources at hand to optimize the cost and improve the technological innovations. In this paper, we have demonstrated the integration of solar photovoltaic and Fuel cell to the Main grid. A diesel generator is used to ma...
![Comparative operation and control strategies between IEC 62898-2 [57]...](publication/337357459/figure/tbl1/AS:826944870432771@1574170429117/Comparative-operation-and-control-strategies-between-IEC-62898-2-57-and-IEEE-20307-7_Q320.jpg)
Within a distributed generation (DG) system, microgrids (MGs) are an alternative approach that may provide both resiliency and efficiency benefits. In this review, an analysis of both research and industrial documents was done. In order to establish a solid foundation of the MGs concept, a comparison of various definitions written by distinguished...
Citations
... Protection issues: some issues are common in DCMGs and DCMGs, such as the restricted fault current contribution of inverter-based DG in islanded mode or the incapacity of single-setting overcurrent relays to protect dual-mode microgrids [70]. However, two additional problems regarding DCMG protection should be taken into account. ...
... Research in [11] details the design and optimization of standalone DC microgrids tailored for both rural and urban applications in India, providing an extensive analysis of the costs, emissions, energy management, and electrical output associated with these systems. The concept of a DC microgrid, discussed in research [12], leverages renewable energy sources to potentially accelerate the provision of electricity to remote and rural areas unconnected to the main utility grid. Additionally, the paper [13] offers an update on the latest developments in DC distribution systems and introduces a comprehensive energy management system (EMS) framework for managing both AC and DC microgrids, including their control and protection mechanisms. ...
The rising demand for various direct current (DC) sources and loads, such as solar photovoltaic (PV) systems, fuel cells, and batteries, is driving the increasing popularity of DC microgrids. These systems are crucial due to their ability to integrate swiftly with the existing electrical infrastructure. In Bangladesh, a significant number of rural households lack access to electricity, underscoring the need for innovative energy solutions like DC microgrids. This paper provides an in-depth examination of DC microgrids, offering a comparative analysis of multiple microgrid systems specifically tailored to meet the needs of rural energy sectors. The study also summarizes the reasons for developing DC microgrids in the rural energy context, exploring how they could advance rural electrification. The paper outlines the schematic design and basic architecture of DC microgrids, emphasizing key components that ensure their efficiency and reliability. It highlights the numerous advantages of adopting DC microgrids, including reduced operational costs, enhanced energy efficiency, and improved compatibility with renewable energy sources and storage systems. In the broader scope of the rural energy internet, this study analyzes DC microgrids to address the critical need for reliable, affordable, and sustainable energy solutions in rural areas. The motivations for implementing DC microgrids within the rural electrical infrastructure of Bangladesh are discussed in detail. Additionally, the paper examines the challenges associated with deploying DC microgrids, potential research directions, and the anticipated impact of these systems on the country's developing rural energy network. This comprehensive analysis aims to contribute to the ongoing efforts to enhance rural electrification in Bangladesh through the strategic deployment of DC microgrids.
... Optimal control of MGs is required to achieve optimal resource usage and energy management. Failure prediction is crucial for avoiding system downtime, and renewables integration is critical for improving the sustainability of MGs [10]. The rise of digital twin technology is a game changer in this industry since the challenges are enormous when compared to previous distributed control systems [11]. ...
This study examines the utilization of digital twin technology as an effective tool for enhancing management and control strategies aimed at optimizing microgrid operations. Thereafter, this paper presents the design of a digital twin microgrid (DTMG) for its optimum operation with self-healing strategies. The design is carried out based on a component-specific twin model using a polynomial regression algorithm to guarantee predictive maintenance and minimize uncertainty. The designed DT replicates the in-house microgrid and establishes real-time bidirectional communication for data handling, examining the system capabilities and input-output properties. Experimental results are presented to verify the effectiveness of the proposed model in terms of accuracy, resource utilization, and error variations over varied input profiles to the MG. Nomenclature () Unoptimized MG input parameters 0 , 1 , 3 , ..., for distributed energy resource. () Unoptimized outputs. () Random system supporting states, Ψ() DERs input matrix containing for a used MG components. Θ() Specific output matrix with. () Supporting state matrix with. Λ Optimized input matrix driven inputs for ℎ DER. Γ Optimized outputs a model is interested in for ℎ DER. Υ Calculated state parameters from raw state matrix for ℎ DER. Physical grid states notation. DT grid acquired states: updated in real-time via grid sensors network. ∕ () Generated power of the renewables. ∕ () Model predicted power. ∕ ++ () Power at = + 1 which is updated in real-time as ∕ ++ () ← ∕. Real-time model error. (,) Load voltage and current. asifat331@gmail.com (Md.M.H. Sifat) ORCID(s): 0009-0000-9579-9596 (Md.M.H. Sifat)
... It critically analyzed various solutions in order to explore various protection issues. Therefore, the authors in [20] reviewed the different protection methods for AC microgrids in the literature. The authors in [20] focused on analyzing the recent state-of-the-art protection strategies including the application of artificial intelligence. ...
... Therefore, the authors in [20] reviewed the different protection methods for AC microgrids in the literature. The authors in [20] focused on analyzing the recent state-of-the-art protection strategies including the application of artificial intelligence. Table 1 gives a brief about all the review studies associated with the protection of microgrids in the last decade. ...
... To address prior challenges [70], the authors proposed combining time-overcurrent relay curves with undervoltage protection concepts to maximize their advantages. This strategy led to the development of relay operation curves as outlined by Equation (20) for K and Equation (21). The variables D, V f , A, p, m, and TMS play specific roles in these equations. ...
Integration of distributed generation systems and diversity of microgrid operations led to a change in the structure of the power system. Due to this conversion, new challenges have arisen when employing traditional overcurrent protection schemes. As a consequence, non‐classical protection schemes have attracted significant attention in the last few years. Engineers and scholars have proposed different non‐standard methods to increase the power protection system and ensure the highly selectivity performance. Although the non‐standard characteristics and their requirements, in general, have been outlined and analyzed in the available literature, protection coordination based on voltage current–time inverse, as a branch of non‐standard optimization methods, has not yet been thoroughly discussed, compared, or debated in detail. To close this gap, this review introduces a broad overview of recent research and developments of the voltage current–time inverse based protection coordination. Focuses on assessing the potential advantages and disadvantages of related studies and provide a classification and analysis of these studies. The future trends and some recommendations have been included in this review for improving fault detection sensitivity and coordination reliability.
... The distribution network has changed due to the integration of (DGs), going from a passive distribution system with power flowing only in one direction to an active network with power flowing in both directions. Numerous technological studies have been carried out to establish protective strategies for DC MG and even more so for AC MG [2]. There have been few studies, nevertheless, on the operation of the hybrid AC/DC system, particularly on developing a reliable protective system. ...
... Several protection challenges face the hybrid network. These challenges may be caused by different reasons as follows [2], [7], [8]: ...
... One issue is the variation in the short-circuit currents (SCC), which depends on the current configuration of the grid. For example, when the operation is in island mode, the magnitude of the SCC is too low [71], [72]. Another issue is related to the bidirectional power flows in the grid, where the operation of conventional protection schemes is not suitable, and the protections must be adjusted to the operating modes of the MGs [73]. ...
... The issues in the grounding and the fault current amplitude reduction have a direct effect on the voltage sag and the value of the fault current [12], [68], [76]. The interruption of current in a DC system produces contact erosion of the circuit breaker (CB) and decreases the useful life of the equipment [71]. The lack of natural zero-crossing does not allow the AC-CB to extinguish the electric arc produced in the opening of an AC breaker [68], [79]. ...
... Variable load demand. [71] Unreliable operation. Load-shedding. ...
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.
... The concept of microgrids has recently gained popularity due to its ability to integrate distributed renewable energy resources, such as photovoltaic and wind energy systems, in an efficient and reliable manner. The growing utilization of renewable energy sources worldwide has further accelerated the development of microgrids [1,2]. A microgrid is a low or medium voltage electrical network that covers a small area and comprises distributed resources, energy storage, and loads [3]. ...
... In power engineering, WT has been used to identify fault events by capturing the transient components holding fault data from the system disturbance signals. Consequently, the extracted transients are then broken into a sequence of wavelets, each of which refers to a time-domain signal covering a particular frequency band with certain information [109]. Reference [110] employs discrete WT and decision trees to detect high-impedance faults in MGs. ...
With the rapid development of electrical power systems in recent years, microgrids (MGs) have become increasingly prevalent. MGs improve network efficiency and reduce operating costs and emissions because of the integration of distributed renewable energy sources (RESs), energy storage, and source-load management systems. Despite these advances, the decentralized architecture of MGs impacts the functioning patterns of the entire system, including control strategy, energy management philosophy, and protection scheme. In this context, developing a convenient protection strategy for MGs is challenging because of various obstacles, such as the significant variance in short-circuit values under different operating modes, two-way power flow, asynchronous reclosing, protection blinding, sympathetic tripping, and loss of coordination. In light of these challenges, this paper reviews prior research on proposed protection schemes for AC-MGs to thoroughly evaluate network protection's potential issues. The paper also provides a comprehensive overview of the MG structure and the associated protection challenges, solutions, real applications, and future trends.
... Different possibilities of faults in the DC distribution network are Pole-Pole (P-P), Positive Pole-Ground (P-P-G), Negative Pole-Ground (N-P-G), Series arc and Shunt arc faults [1]. Generally, DC cables offer low impedance in the fault scenario and as a result the rate of rise of the fault current is very high [3][4][5]. To protect the DC microgrid from these currents, different protection schemes have been introduced. ...
... Applying the derivative to (5) to obtain the double derivative equation for the differential current, which is used to detect the fault, yields: ...
This paper presents fault detection, classification, and location for a PV-Wind-based DC ring microgrid in the MATLAB/SIMULINK platform. Initially, DC fault signals are collected from local measurements to examine the outcomes of the proposed system. Accurate detection is carried out for all faults, (i.e., cable and arc faults) under two cases of fault resistance and distance variation, with the assistance of primary and secondary detection techniques, i.e. second-order differential current derivative $$\left( {\frac{{d^{2} I_{3} }}{{dt^{2} }}} \right)$$ d 2 I 3 d t 2 and sliding mode window-based Pearson’s correlation coefficient. For fault classification a novel approach using modified multifractal detrended fluctuation analysis (M-MFDFA) is presented. The advantage of this method is its ability to estimate the local trends of any order polynomial function with the help of polynomial and trigonometric functions. It also doesn’t require any signal processing algorithm for decomposition resulting and this results in a reduction of computational burden. The detected fault signals are directly passed through the M-MFDFA classifier for fault type classification. To enhance the performance of the proposed classifier, statistical data is obtained from the M-MFDFA feature vectors, and the obtained data is plotted in 2-D and 3-D scatter plots for better visualization. Accurate fault distance estimation is carried out for all types of faults in the DC ring bus microgrid with the assistance of recursive least squares with a forgetting factor (FF-RLS). To verify the performance and superiority of the proposed classifier, it is compared with existing classifiers in terms of features, classification accuracy (CA), and relative computational time (RCT).
... The fault currents may become bi-directional when inverter based DGs are embedded into the grid. The conventional overcurrent relay will be invalid in this case [6,7]. The protection methods for inverter-dominated microgrids can be classified into directional overcurrent relay-based method, distance relay-based method, current differential based method, voltage-based method, traveling wave-based method and fault current source based method. ...
The modern microgrids are becoming very
complex due to the growing penetration levels of renewable
distributed generations (RDGs). The integration of RDGs in
power system can lead to change in the fault current level and
network topologies, which in turn cause the overcurrent and
relay coordination issues. Design and selection of a proper
protection scheme is very important for reliable and safe
operation of microgrid. In this paper, the effect of different
penetration levels of renewable DGs and loads has been
considered for an adaptive protection coordination scheme of
regionalized microgrid. The main focus of this paper is on use of
optimization algorithm to obtain maximum current along each
line. Based on these values, proper pick-up current setting can
be determined for each over-current protection. Case studies
have been performed with the different ranges of penetration
level of RDGs and load demands. Results have shown the
strength of proposed algorithm. This analysis can be very
helpful to maintain the reliability and security of the grids with
high penetration level of renewable generation.
