Summary The demand of electric energy is increasing globally, and the fact remains that the major share of this energy is still being produced from the traditional generation technologies. However, the recent trends, for obvious reasons of environmental concerns, are indicating a paradigm shift towards distributed generation (DG) incorporating renewable energy resources (RERs). But there are associated challenges with high penetration of RERs as these resources are unpredictable and stochastic in nature, and as a result, it becomes difficult to provide immediate response to demand variations. This is where energy storage systems (ESSs) come to the rescue, and they not only can compensate the stochastic nature and sudden deficiencies of RERs but can also enhance the grid stability, reliability, and efficiency by providing services in power quality, bridging power, and energy management. This paper provides an extensive review of different ESSs, which have been in use and also the ones that are currently in developing stage, describing their working principles and giving a comparative analysis of important features and technical as well as economic characteristics. The wide range of storage technologies, with each ESS being different in terms of the scale of power, response time, energy/power density, discharge duration, and cost coupled with the complex characteristics matrices, makes it difficult to select a particular ESS for a specific application. The comparative analysis presented in this paper helps in this regard and provides a clear picture of the suitability of ESSs for different power system applications, categorized appropriately. The paper also brings out the associated challenges and suggests the future research directions.

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Summary In this paper, a novel control strategy is proposed for a hybrid energy storage system (HESS), as a part of the grid‐independent hybrid renewable energy system (HRES), to maintain active power balance among different constituents of HRES. The considered HRES includes a wind energy conversion system (WECS), a photovoltaic (PV) system, the HESS comprising the battery energy storage system (BESS) and supercapacitor energy storage system (SCESS), dump load, and a set of critical and noncritical loads. The proposed control strategy is executed into two parts: In the first part, the HESS controller maintains the active power balance among different constituents of HRES under variable operating conditions (viz, wind speed, solar irradiance, and load). The low‐frequency components of imbalance power are diverted to BESS for its smooth charging/discharging while the high‐frequency components are diverted to the SCESS, thereby reducing the stress on BESS. Further, the state of charge of the HESS is maintained within the limits and hence increasing its operating life. In the second part, the three‐phase inverter controller, based on vector control technique, regulates the three‐phase AC voltage magnitude and frequency within limits against any perturbation. The novelty of the proposed control strategy lies also in the fact that some portion of the power, which remains uncompensated by BESS when using conventional low pass filter (LPF) scheme, is compensated by SCESS by generating reference current corresponding to this uncompensated power. Further, the synergetic use of the typical HRES—PV system and WECS—and the typical HESS—BESS and SCESS—is also a new proposition. Simulations are carried out in MATLAB/Simulink and the results demonstrate the effectiveness of the control strategy in terms of active power balance of HRES, regulation of DC link voltage (VDC), three‐phase AC voltage and frequency, and maintaining SoC constraints of HESS in transient as well as steady state conditions.