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• Aim: Improved reliability and performance of the HRES with Hybrid battery architecture - VRB flow battery and Li-ion battery. • A VRB battery for peak shaving and long time storage and a Li-ion battery to match transients and ramp rate limiting. • Sizing and performance results prove to be sufficient, consistent and better than earlier literature. • Optimal sizing and effective operation lead to justified and profitable investment costs for the hybrid storage. • Complete study with forecasting, scheduling, energy management and techno-economic analysis of HRES provided. Energy storage systems are becoming more and more important for integrating higher levels of varying and intermittent renewable power into the grid. As we have energy storages with different characteristics and applications, hybrid storage solutions combining various technologies to meet different applications are fast developing. In this paper, an efficient energy management strategy is proposed for a VRB and Li-ion hybrid battery system to be integrated with a grid-connected wind-PV Hybrid Renewable Energy System (HRES). The operation of the generating system and the storage batteries are evaluated using Matlab/Simulink and techno-economic analysis is carried out. The results demonstrated successful implementation of the hybrid system with improved deliver ability and storage lifetime. [ABSTRACT FROM AUTHOR]

Recently multilevel inverters (MLI) have attracted more attention in research and industry, as they are changing into a viable technology for several applications. The concept of MLI was introduced for high power and high/medium voltage applications as they can provide an effective interface with renewable energy sources. Developing of reduced switch MLI topology has been a rapid research topic since the past decade, which has not been reviewed so far. Therefore, this review article focuses on the different reduced switch MLI topologies under three categories such as symmetric, asymmetric and hybrid configurations. The important knowledge on these topologies is carefully tabulated based on the three categories in the comparison tables to understand the essential parameters of the MLI topologies. These configurations are not only generating higher voltage levels to improve the power quality but also to reduce the passive filter requirements. Also, this review includes a detailed perspective of various modulation techniques and control strategies for MLI topologies. In addition to that, the different performance parameters of MLI and its calculation methods are discussed with appropriate mathematical expression. This review will help in the selection of appropriate MLI topology for FACTS, motor drives and renewable applications. [ABSTRACT FROM AUTHOR]

The contribution of power generation from converter-dominated renewable energy sources (RES) has increased enormously. Consequently, the system inertia is decreasing, and it impacts the frequency of the system. With large-scale integration of power electronic inverter-based power generation from RES, inertia from energy storage devices would be unavoidable in future power grids. In this paper, the inertia emulator is formed with a supercapacitor (IE–SC) to improve inertia in a low inertia grid. To emulate the inertia in a low inertia grid, this paper proposes a fuzzy logic controller-based emulated inertia controller (FL-EIC) for an inverter attached to IE–SC. The proposed fuzzy logic controller estimates the inertial power required based on the frequency deviation and rate of change of frequency (ROCOF). The output of the fuzzy controller adds to the conventional emulated inertia control (EIC) technique to alter the load angle for the power electronic inverter of IE–SC. Specifically, the proposed FL-EIC achieves inertia emulation by proportionally linking the time derivative of the grid frequency and frequency deviation to active power references of IE–SC. A comparison of the conventional EIC and FL-EIC is carried out to prove the effectiveness of the proposed FL-EIC. Furthermore, real-time simulations with the help of the OPAL-RT real-time simulator (OP 5700) are presented to validate the advantage of the FL-EIC. [ABSTRACT FROM AUTHOR]

This paper proposes an intelligent battery management system (BMS) implementing two large Vanadium Redox Battery (VRB) flow batteries in a master-slave mode to provide grid-level energy storage for a wind-solar hybrid power system. The proposed BMS is formulated to effectively meet a predetermined power dispatch formulated based on forecasted wind and solar data while incorporating features like peak shaving and ramp rate limiting. It is compared to a single battery module operated system to showcase the advantages of the proposed intelligent dual battery module in terms of appreciable reduction in battery size and costs while exhibiting improved lifecycle performance. The battery size is optimized based on heuristic optimization algorithms and modelled in Matlab/Simulink environment. An intelligent fuzzy-based BMS is used to control the dual VRB model to ensure optimized power sharing between batteries. The simulations were carried out and an in-depth economic analysis conducted to analyze the costs and other financial metrics of the hybrid project. Results proved the advantages of the dual battery with the proposed BMS and fortify that the introduction of time-based tariffs and other incentives will further make investments in VRB highly attractive for renewable applications. [ABSTRACT FROM AUTHOR]

This paper proposes a new multilevel inverter (MLI) topology that utilizes trinary sequence for the dc sources. It gives maximum output voltage level with minimum dc source and switch count when compared to other sequences, such as symmetric, natural, binary, and quasi-linear. This is due to the fact that the trinary sequence generates of all additive and subtractive combinations of input dc levels in the output voltage waveform. The concept is implemented on a 9-level asymmetric MLI using only four active devices. Multicarrier unipolar pulsewidth modulation technique is adopted to create the switching pulses. Theoretical calculation of total harmonic distortion in both voltage and current waveforms has been performed using asymptotic time domain formula. These values are compared with simulation and experimental values for different modulation indices. Power loss calculation for proposed topology is discussed with appropriate mathematical equations. [ABSTRACT FROM AUTHOR]