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This paper presents a reliable microgrid for residential society with control methods to design grid forming inverter (GFI) to emulate the seamless-synchronization features to deal with the dynamic concerns of the grid. In this microgrid a photovoltaic (PV)-based GFI with a control scheme in parallel with a PV-battery supported inverter with an enhanced current control is considered to operate under non-ideal grid voltage conditions. The PV-GFI is adaptable to operate either in islanded mode (IAM) or grid integrated mode (GIM) depending under the grid conditions. An adapted power control technique is implemented such that power demand of local loads and harmonic currents are compensated by respective distributed generation. Moreover, the active power demand of all local loads is shared between the main grid and respective local DG. The adapted power controller achieves transient free operation even under the load disturbances. The proposed control methods of microgrid are validated in simulation under various operating conditions.

With increased penetration of renewable power and the nonlinear loads in the distributed generation (DG) systems, increased power quality concerns are exhibited in the active distribution networks, especially the challenges associated with the current and voltage harmonics in the system. Various conventional harmonic compensation techniques are developed for voltage-controlled DG inverters in past, majority involve either multiple proportional-integral (PI) or proportional-resonant (PR) controllers in eliminating grid current harmonics. The current-controlled inverters, on the other hand, are not preferred in industrial applications, accounting to their wide variations in the switching frequency. A novel and adaptive harmonic voltage control is developed here, for voltage-controlled DG inverters, which neither uses any PI regulators nor imposes stability issues associated with nonideal implementation of infinite gains of PR controllers. Interestingly, the developed control logic can be used for DG inverters, both in grid-connected and off-grid operational modes. Furthermore, this strategy allows a network operator to use this as an additional supplement that can be enabled/disabled as per the network requirement. The control logic exploits the property of an optimal-switching-vector controller, i.e., accurate output voltage tracking. Simulations results demonstrate the effectiveness of the controller, to suppress grid current harmonics and load voltage harmonics in grid-interfaced (GI) and off-grid modes, respectively, ultimately satisfying the mandatory IEEE standard-1547. Experimental results verify the viability of the controller for practical applications.

Differential current protection has been a reliable approach for line protection in DC systems. However, due to its dependence on communication for terminal current information, resiliency of such a protection approach is poor against external cyber intrusions (ECI) of different types, i.e., false data injection (FDI) and time synchronization attacks (TSA). As a result of which, the system is prone to collapse due to line tripping in the presence of coordinated ECIs. The scope of paper is to propose a resilient protection approach for medium voltage DC (MVDC) microgrids differentiating between the real faults and the ECIs in a system. The approach also detects ECIs on an adjacent line occurring simultaneous to a real fault where the system deploys current limiting reactors (CLR). Phase-modal transformation is carried out to obtain the mode voltages (line and zero) across these CLRs. The mode voltages across the faulty mode networks are utilised along with differential current protection to propose a resilient protection approach against ECIs, which is sensitive to high impedance faults (HIFs). Further, a sensitivity function is formulated which gives the variation of decisive variables i.e., mode voltages with respect to change in decisive parameters i.e., fault resistance and fault location.

This work aims to develop a solar- battery energy storage (BES) based system, which ensures an uninterruptable supply to loads irrespective of the availability of the grid. This system comprises of a solar photovoltaic (PV) array, a BES, the grid and local residential loads. A new control is implemented such that the active power demand of residential loads, is fed from the PV array, a BES unit and the utility grid. In this system, the power control operates in different power modes, which delivers the benefits to the end-users with the integration of BES and an excess of PV array power, which is sold back to the grid. For this, effective control logic is developed for the grid-tied voltage source converter (VSC). Moreover, this system deals with the issue of an integrating power quality enhancement along with the power generation from the solar PV source. The cascaded delayed signal cancellation (CDSC) based phase-locked loop (PLL) is implemented for grid synchronization during the grid voltage distortion. The developed control is easily implemented in a real-time controller (dSPACE-1202).

An air conditioner load has a major role in power consumption from utility grid in tropical countries. Most of the air conditioning systems are migrated to variable speed drive technology that optimizes the power utilization. Renewable energy sources like photovoltaics (PV) and energy storage system (ESS) like batteries produce DC power. In this paper, considering the advantages of variable speed drive technology, the power is directly injected to the DC side of the variable speed drive from PV array and the battery. The compressor at the outdoor unit consumes major portion of power from the grid and therefore the additional power is integrated to this unit to support the grid. The voltage level of the battery is boosted to match with the DC bus voltage level of the grid using a bidirectional isolated DC-DC converter. A low power DC-AC conversion stage is present to run the indoor unit and to supply the auxiliary power. In this methodology, air conditioner is operated uninterruptedly and high power DC to AC (50 Hz) conversion stages are eliminated, thus it reduces the blukiness of the system, cost and conversion losses. A seamless bidirectional power is exchanged between the battery and utility grid without interrupting the main operation of the air conditioner.

A time domain dynamic model of impedance has been developed in this work for online estimation of Thevenin’s equivalent impedance of a network seen from a bus. Although the time domain impedance (ratio of instantaneous AC voltage and current) is undefined in a period, a zone of definition and workability has been defined. Using the zone of definition, an observable dynamic model has been constructed. An algorithm is developed which uses the model along with a Kalman filter to estimate the Thevenin’s impedance. The algorithm takes the time domain instantaneous voltage and current of the bus as its input. Simulation bus data has been generated by EMTP/PSCAD and the algorithm has been developed in MATLAB. The model helps to successfully estimate the network Thevenin’s equivalent with better steady state and transient tracking ability than the frequency domain based DFT algorithm. The algorithm has been implemented in hardware using Opal-RT systems.

The dual active bridge (DAB) converter contains both AC and DC states. Hence, state space average modeling of DAB is intricate. In the literature, several models of DAB have been developed to reconstruct the AC state. However, full order models provide better accuracy than reduced order models. Frequency domain based modeling captures the total behaviour of the converter such as generalized average modeling (GAM) or series based solutions. However, with the consideration of more harmonics in the model, derivation of state equations and thus state matrices become tedious. This paper proposes a harmonic state space (HSS) modeling framework for DAB that overcomes above obstacles and accurately models both the AC and DC states depending on the inclusion of the number of harmonics in it. The modeling framework described here is applicable to single, dual and triple phase shift modulation schemes. This modeling framework presents a straight forward approach and has a definite structure, which presents flexibility and ease in deriving the input-output relationship. Both large signal and small signal models are derived and analyzed. This model is validated by time domain simulation, performed on MATLAB/Simulink. Experimental investigations on a prototype of DAB also validate this model.

A reduced-order model of a converter-dominated microgrid system may not resemble its full-order system associated with uncertainties. This paper aims to provide a singular perturbation-based contraction framework for model order reduction in converter-dominated uncertain microgrid systems. For this purpose, the concerned microgrid system is modeled as a generalized multi-timescale system, and certain sufficient conditions are derived such that convergence between the trajectories of the uncertain full-order and the corresponding reduced-order model can be guaranteed. The contraction theory-based strategy also provides explicit parameter-dependent expressions for quantifying discrepancies. The derived results are utilized to analyze the inverter-based microgrid system?s convergence behavior and obtain uncertainty bounds on its parameters. Further, the effects of modeling uncertainties and different loading conditions on the reduced-order model?s validity are also discussed. It is observed that for any uncertainty associated with the microgrid parameters that are within the bounds of checkable conditions, the states of the reduced-order microgrid model converge to that of the uncertain full-order system. Further, it is also shown that the obtained discrepancy expressions are more precise than state of the art.

This paper presents a delay and a package drop compensator to address the variable latencies which arise in a wide area power system stabilizer (WAPSS). The vulnerability of data-driven control (DDC) based WAPSS to these latencies is specifically highlighted. The uniqueness of the proposed delay compensator (DC) is that it is designed to address not only the large deviations in delay mean value but also the variations around the mean value by careful reformulation of the delay in terms of its statistical features. Moreover, a new approach is proposed for package drop compensation, which considers nonlinearity in its formulation. The proposed package drop compensation uses the technique of dynamic linearization (DL) and pseudo partial derivative (PPD). Rigorous analysis is carried out to observe the effect of variable delay and package drop on the damping performance of DDC-WAPSS. It is shown that the damping performance of DDC-WAPSS improves when the proposed compensation techniques are used. The proposed DC and the nonlinear system based package drop compensator achieve improved compensation compared with the customary ones.

The environmental concerns linked to traditional power generation methods have driven solar photovoltaic (SPV) systems to be established as a clean and viable alternative power solution [1]. However, SPV systems are associated with low energy conversion efficiency attributes. This highlights the need for an efficient power conversion system [2]. SPV sources showcase a nonlinear currentvoltage (I-V) characteristic that is subject to variation with concurring insolation and temperature conditions. Consequently, this alters the maximum power point (MPP) as well as the maximum power generation. As a result, the literature of this field reiterates the need for efficient maximum power point tracking (MPPT) techniques. Prior works have established a variety of solutions to track the MPP; each of them possesses its pros and cons [2]. Notably, a number of conventional MPPT techniques will fail to track the MPP under partial shading conditions [2]. Although some intelligent techniques can still achieve MPP, these methods oscillate around the MPP due and as a result, some of the available power is not utilized. The oscillating character of these MPPT techniques occurs under uniform conditions as well [3]. Hence there is a definite need to address this issue by determining

This article proposes a computationally simple strategy by using a three-sample-based technique for a grid-connected inverter in a single-phase active distribution system. The proposed control is to improve the performance during varying grid conditions such as voltage sag, swell, and frequency swing. A comparative analysis between the proposed controller and the conventional second-order generalized integrator phase-locked loop (PLL) based controller for dynamic grid conditions in weak-grid scenario has been presented. Additionally, a frequency domain analysis via describing function method is used to model the dynamics of nonlinear hysteresis current controller to analyze the closed-loop stability of the system. Further validation of the proposed control algorithm is simulated in MATLAB/SIMULINK environment for various scenarios. To establish the effectiveness of the proposed approach in real time, the proposed control strategy is tested in a 1 kVA based experimental setup.

Nanotherapy has emerged as an improved anticancer therapeutic strategy to circumvent the harmful side effects of chemotherapy. It has been proven to be beneficial to offer multiple advantages, including their capacity to carry different therapeutic agents, longer circulation time and increased therapeutic index with reduced toxicity. Over time, nanotherapy evolved in terms of their designing strategies like geometry, size, composition or chemistry to circumvent the biological barriers. Multifunctional nanoscale materials are widely used as molecular transporter for delivering therapeutics and imaging agents. Nanomedicine involving multi-component chemotherapeutic drug-based combination therapy has been found to be an improved promising approach to increase the efficacy of cancer treatment. Next-generation nanomedicine has also utilized and combined immunotherapy to increase its therapeutic efficacy. It helps in targeting tumor immune response sparing the healthy systemic immune function. In this review, we have summarized the progress of nanotechnology in terms of nanoparticle designing and targeting cancer. We have also discussed its further applications in combination therapy and cancer immunotherapy. Integrating patient-specific proteomics and biomarker based information and harnessing clinically safe nanotechnology, the development of precision nanomedicine could revolutionize the effective cancer therapy.

The dual active bridge (DAB) is one of the useful interfaces for the bidirectional power exchange between two buses with galvanic isolation. In this article, a design framework is given in the analog domain that completely fulfills the operational features of a DAB under phase angle modulation. This is a cost-effective solution with configurable control parameters and easy to implement using well-established semiconductor integrated circuit (IC). Moreover, it provides an efficient way to study the behavior of power converters. A closed-loop control for bidirectional power exchange is established. For that, a control-to-output current transfer function is derived analytically considering the dc and first-order harmonic terms and verified experimentally. A small scale laboratory prototype of DAB is set up for the validation of the concept. It is shown that the design architecture has the facility for supervisory control that is useful for battery charging/discharging, microgrid application, etc.

This article deals with the parallel operation of photovoltaic (PV), battery energy storage (BES), and diesel generator (DG) for standalone ac/dc system. It is known that the maximum penetration of PV systems in DG-based power system is limited in the range of 40%–60%. When the PV capacity becomes comparable to DG capacity, the system suffers from stability and synchronization issues. Hence, this article proposes a dc droop-based hierarchical control of the PV-BES-DG system based on dc integration at a common dc bus. The dc integration alleviates the scalability limit on PV and facilitates better control of the hybrid system than ac counterpart. Moreover, an optimal regulator-based secondary control is proposed to ensure optimal load sharing among DG and BES. Further, a power management scheme (PMS) is designed to ensure reliable operation of the standalone system during source and load power imbalances and operation under critical state of charge limit condition of BES. Also, the PMS constraints the operation of DG below a defined low-level loading. Further, small signal stability analysis is presented to analyze the effects of droop and optimal regulator gain on the system's stability. The laboratory-scale prototype is developed to evaluate the performance of proposed PMS and dc droop-based hierarchical control of the PV-BES-DG system.

This article presents a decentralized adaptive droop-based control for active power sharing between the parallel inverters in autonomous microgrids. This article is focused on improving the transient performance of the system proposing a robust controller. The analysis does not require load current measurement where the Lyapunov analysis-based control takes load current as a disturbance to the system. The mathematical analysis takes a more practical form of LC filter configuration where the dynamics due to resistances across the LC is also considered. Controller gain conditions are considered by employing a detailed Lyapunov analysis. A comparative study of the conventional droop control with the proposed adaptive droop control is included in this article. MATLAB has been employed as the Simulink platform for the comparative study. In addition, for experimental verification, an FPGA-based hardware setup has been developed and the related results are presented to verify the real-time operation of the proposed adaptive control.

In low-voltage dc distribution networks (DDNs), the load terminals typically employ voltage-source inverters to provide ac supply to the consumers. These load terminals can potentially experience poor voltage regulation especially in the presence of intermittent photovoltaic sources and uncoordinated charging patterns of plugged-in electric vehicles. Variations in power absorption and generation at different points can potentially create significant voltage drop/rise at the load terminals and may reduce the power quality at the ac side of the loads. In order to mitigate this issue, this article suggests a real-time coordinated supervisory control strategy that estimates the present state of the network and generates a set of references for the controllable sources such that the load voltage deviations are minimized. This article also proposes a power-electronic-converter-based soft open point (SOP) that provides a seamless connection of the remote end and gives an additional degree of freedom to control the circulating current among the feeders. Detailed description and control strategy of the SOP is presented. Steady-state analysis carried out on a three-feeder DDN is presented with and without the proposed SOP. Real-time simulation with an Ethernet-based transmission control protocol/Internet protocol communication system along with experimental results is presented to validate the implementation and effectiveness of the control strategy.

The increase in the numbers of electric vehicles (EVs) is seen as an upgrading of the existing vehicles for various reasons. This calls for an in‐depth analysis of the heart of these vehicles—the motor. A motor in an electric vehicle propulsion system is a crucial component that has the ability to affect the efficiency, weight, cost, reliability, power output and performance. Hence a detailed comparative study, that compares the existing types and topologies of various motors, is the need of the hour. The various motors that can be used in electric traction, namely DC, induction, switched reluctance, permanent magnet brushless AC motors and permanent magnet brushless DC motors, are reviewed in view of their capabilities with respect to EV propulsion. A detailed review is presented of existing motors and the application of power electronic techniques to EVs, and recommendations for some new designs of brushless DC motors. These include permanent magnet hybrid motors, permanent magnet spoke motors and permanent magnet inset motors.

This article presents a grid-connected single-stage photovoltaic (PV) system using an adaptive normalized notch filter (ANNF). An unknown time-varying fundamental frequency is precisely estimated from a normalized notch filter and consequently, the fundamental load component is extracted using this algorithm. The convergence of the algorithm is independent of both amplitude and the frequency of the fundamental component, and therefore, this algorithm is robust to these changes in the load current. The adaptive estimation of fundamental load current with perturbations on load/grid side system is well analyzed. The ANNF based control strategy is not only efficient in fundamental extraction, however, it also achieves the objectives of supplying real power to the grid, grid currents balancing, and power factor correction. Moreover, this algorithm is robust to harmonic/ distorted/ unbalanced grid voltages caused at far radial ends in the weak distribution network. Elaborated simulation results are presented to show the effectiveness of the strategy. A prototype is developed to validate this control strategy at various perturbations. Under all operating conditions, test results are found satisfactory.

The article presents a corrective control philosophy of a grid tied inverter for adapting the instability incurred at the Point of Common Coupling (PCC) due to uncertainty in the utility grid. It has been observed that the converter impedance which is dependant on the control system loop have a considerable impact on the stability. Therefore, the proposed philosophy explores the participation of the control parameters in shaping the return ratio trajectory which consequently modifies the stability margins of the system. A sensitivity function has been formulated which gives the gradient of each point in the return ratio trajectory to changes in the control parameters. The formulated function has an additional advantage of being grid parameter independent, thus increasing robustness and reducing complexity. An adaptive multi-variable, multi-degree of freedom feedback philosophy using the sensitivity gradients has been proposed to dynamically reach the optimum value of the control parameters in case of grid impedance change. The result shows that the proposed philosophy successfully brings stability to the system in the presence of a weak grid. As well as it preserves the dynamic performance requirements of the converter control.