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The fuzzy graph theory uses a substantial and important role in modelling and structuring many optimization problems. DIfferent type of uncertainties exist in most of the optimization problems in real lIfe scenarios due to indeterminate and incomplete information and it is a challenging task for the expert to design those optimization problems applying fuzzy graph. To design the incomplete, uncertainty and vagueness in graphical optimization problems, several extensions of graph theoretical ideas are proposed. The idea of neutrosophic graph plays an important role to manage the uncertainty, linked with the indeterminate and incomplete data/information of any optimization problem. In this manuscript, we present the idea of regular neutrosophic graph, strong neutrosophic graph, bipartite neutrosophic graph, regular neutrosophic graph, and regular strong neutrosophic graph. We also introduce six different operations on neutrosophic graph, viz., cartesian product, composition, join, direct product, lexicographic and strong product. [ABSTRACT FROM AUTHOR]

Microgrids are often accomplished with power‐dense and energy‐dense hybrid storage systems for the assured improvement in the stability and the awake time. The conventional droop based steady‐state power bifurcation strategies for the energy‐dense storage elements can efficiently improve the awake time. However, the improvement in the stability and the robustness demands accurate transient demand allocation. The constant cut‐off frequency‐based physical power decomposition filter cannot ensure an accurate transient demand allocation, particularly, while the demand is fluctuating and uncertain. Therefore, the study proposes the concept of pseudo‐power decomposition filter. The concept of the pseudo‐decomposition filter has been executed for the microgrid through the novel selected power component droop. The real‐time performance of the proposed concept has been evaluated in the BTS‐7960 packaged‐Metal Oxide Semiconductor Field Effect Transistor (MOSFET) ‐based hardware platform, regularised through the ARM Cortex A‐72 based digital signal processor. In respect to the conventional linear droop, the improvement through the concept in the power decomposition and the allocation of transient demands is significant. [ABSTRACT FROM AUTHOR]

Trends of incorporating distributed renewable energy sources into the power distribution network through power electronic mediums have substantially increased. It results in a decaying inertial response and, consequently, the natural damping. Eventually, the distribution network is increasingly becoming sensitive towards the uncertainties. The increasing sensitivity issue in the power system drives the present research trends towards a solution termed virtual synchronous generator (VSG). A VSG has the potentiality to mimic the characteristics of a physical synchronous generator (SG). In this study, to expose the suppressed potentiality of a VSG, an innovative concept of virtual gyratory mass is proposed. To achieve a satisfactory performance, the model parameters of the VSG have to be well chosen. Conventionally, optimal parameters are selected by comparing it with a physical SG and thus, it remains constant in its operational period. However, the constant inertial VSG cannot suppress the system sensitivity under the random degree of uncertainty. Therefore, to ride through this issue, the concept of dynamic damping co-efficient is introduced in this study. The damping coefficient is tuned in real-time through the proposed fuzzy tuned dynamic synthetic inertia mechanism. The improvement in the performance is validated in the real-time experimental prototype setup. [ABSTRACT FROM AUTHOR]

This study proposes a dual‐stage cascaded operational control to attain a seamless transition of a standalone microgrid to a grid‐connected microgrid system. In order to safeguard the microgrid's stability, the strategy incorporates a bi‐directional converter. A dynamic reference frequency loop‐based resynchronisation controller is proposed to control the operation of the bi‐directional converter. The stage‐I operates to maintain the converter end system parameters equal to the utility. This creates a pseudo‐equalisation between the converter connected microgrid parameters and the utility. As a result, the simultaneously operating synchroniser controller switches the resynchronisation switch. The stage‐II of the proposed strategy addresses the transition controller, which switches the microgrid's mode of operation from standalone mode to grid‐connected mode. The grid connected bi‐directional converter‐based microgrid builds up its parameter equal to the utility. When microgrid builds up to a level that it satisfies the set values of the bypassing controller, it signals the bypassing switch (BS) to operate. In this study, the BS plays an essential role in bypassing the bi‐directional converter. The test system designed to study the proposed strategy is simulated on the podium of Matlab 2015b/Simulink. [ABSTRACT FROM AUTHOR]

Control over the voltage and the frequency instabilities in a grid‐forming microgrid due to the power mismatch conditions become the point of concern. Therefore, the study implements a self‐tuned proportional–integral integrated active power–voltage drooping and reactive power–frequency boosting control strategy for the precise power sharing among the distributed generators. Furthermore, to handle the power deficit scenarios and protect the system from the blackout, a system independent and priority‐based adaptive three‐stage load shedding strategy is proposed. The sensitivity of the strategy depends on the system inertia and is computed according to the varying absolute rate‐of‐change‐of‐frequency. The strategy incorporates the operation of a hybrid storage system comprised of battery and supercapacitor present in the microgrid, to provide a reliable power supply to the customers for a considerable time rather than a sudden load shedding. The effectiveness of the proposed strategies is investigated on a modified IEEE 13‐bus system. The study is simulated in the time domain, on the podium of MATLAB 2015b. [ABSTRACT FROM AUTHOR]

This paper develops state variables for storage units and evaluates their performance in hybrid storage systems. To ensure an equalised storage utilisation factor, a self-tuned dynamic exponent controller is designed. The decentralised controller manages the state of charge within the high specific energy based hybrid storage units. Furthermore, to address the instability of the dc bus voltage, this paper proposes a fuzzy logic integrated dynamic PI based controller. The designed controller manages the state of power by regulating the compensation level of the high specific power based hybrid storage units during the transients. The improvement of the system stability through the proposed controllers is evaluated using the Nyquist stability criterion. [ABSTRACT FROM AUTHOR]

Summary: The study converges the system stability for the steady‐state and transient state simultaneously. The battery and compressed air storage systems are considered to address the steady power demand, on the other hand, flywheel and supercapacitor‐based storage unit functions to minimize the transient system fluctuation. The study derives the integrated state variables of the hybrid unit to implement the proposed control strategies. The paper proposes a self − tuned dynamic exponent control strategy to regulate the charge equalization among the battery and compressed air, as they possess a large energy per unit volume. Similarly to regulate the high power content of the flywheel and supercapacitor, a fuzzy tuned dynamic PI is proposed. The proposed strategies ensure an efficient decentralized control among the hybrid units. The designed system under study integrated with the control strategies is tested under the critical operational constraints of load and generation. Further the improvement of the system stability is analyzed using the Nyquist's stability criterion. [ABSTRACT FROM AUTHOR]

In this research endeavor, a novel approach has been presented to enhance the power quality through a Photovoltaic (PV)-based Dynamic Voltage Restorer (PV-DVR). The proposed work is designed to address voltage fluctuations, flicker, and harmonics within medium or low voltage micro-grid systems. Unlike existing DVR systems that often neglect injected harmonics and converter losses, in the proposed work there is an integration of a PV-fed multilevel inverter system employing Selected Harmonic Elimination and Moderation-based Pulse Width Modulation (SHEAM-PWM). This innovative configuration, coupled with a DC – DC boost converter and a series injection transformer, not only aims to alleviate voltage stress on devices but also optimizes the number of switches to minimize switching losses. The proposed setup successfully reduces the overall voltage Total Harmonic Distortion (THD) to a significant extent, delivering superior dynamic performance. To determine optimal switching angles for the SHEAM-PWM technique, ensuring the elimination or mitigation of the maximum number of harmonics from the output voltage waveform, we employ the Biogeography-Based Optimization (BBO) approach. The computation of these angles is performed offline to eliminate lower-order harmonics, and the results are stored in the microcontroller’s memory using mixed model equations for online applications. The efficacy of our proposed method is demonstrated through both simulation and experimental validation in a real-time laboratory system. The simulation and experimental results obtained underscore the potential utility of our technique for Dynamic Voltage Restorer (DVR) applications, particularly those requiring low harmonic injection. The proposed method introduces a comprehensive and innovative solution for power quality enhancement, combining PV technology, multilevel inverter systems, and advanced optimization techniques. The proposed PV-DVR system exhibits promising results, showcasing its potential for practical implementation in residential micro-grid systems with a focus on minimizing harmonics and ensuring efficient grid compensation. [ABSTRACT FROM AUTHOR]