This paper presents a grid-tied, solar energy conversion-battery energy storage system with an autonomous control method for critical load applications. In order to improve grid current dynamics and ensure that balance power is exchanged as an active power with utility, direct current management of voltage source converter utilises the least mean fourth method. The intermittent nature of solar photovoltaic also affects dynamics and power quality of grid c. This paper presents a grid-tied, solar energy conversion-battery energy storage system with an autonomous control method for critical load applications. In order to improve grid current dynamics and ensure that balance power is exchanged as an active power with utility, direct current management of voltage source converter utilises the least mean fourth method. The intermittent nature of solar photovoltaic also affects dynamics and power quality of grid current. A potential solution to such a situation evolves by using a bidirectional, DC/DC converter, which interfaces the battery energy storage (BES) system with DC link. Dual-loop DC/DC converter control keeps the BES system charging and discharging current within pre-set limits and also simultaneously regulates DC link. State-of-charge control gets incorporated through a dual-loop control to prevent the BES system from overcharging/deep-discharging. Dual-loop voltage control with harmonic compensation is used to manage load voltage amplitude and frequency in islanded mode. Auto-grid synchronisation is realised by using a first-order, frequency-locked loop (FLL) technique. Using FLL also reduces DC offset, harmonics and inter-harmonics even in problematic grid circumstances. The presented investigation also proposes a step-by-step controller parameter design procedure based on frequency domain stability restrictions. Experimental results with switching frequency 10 kHz, using OPAL RT-5600 validates the expected system response.••Battery energy storage system charge controller••Solar energy conversion system••Energy management control scheme for SEC-BES system••Power quality improvements••Seamless transition between grid-connected and islanded modesBattery energy storage (BES)Frequency-locked loop (FLL)HarmonicsPower quality (PQ)Electricity demand is growing worldwide due to the increasing population and continuous depletion of non-renewable energy resources (RESs). Generation from non-renewable resources such as fossil fuel, gas, oil, etc., becomes costly and increases pollution. A probable solution appears in the usage RESs such as solar energy, which is readily available [1,2]. A major advantage of solar photovoltaic (PV) is that it is independent of end-user location in accordance with applications (such as remote domestic applications and urban office complexes). Generated electricity from PV is being widely used in applications such as, battery energy storage (BES) system charging, uninterrupted power supply (UPS) in standalone/grid-connected modes and critical load applications like health support systems, information technology-enabled services, which cannot afford power cut [,,, ]. Therefore, a grid-tied solar energy conversion system (SECS) is a better option for supplying power to critical loads.During night and rainy seasons, solar energy is unavailable and irregularities occurring in utility may reduce the overall system reliability. BES system therefore plays an important role towards system reliability [8,9]. A two-stage SECS with direct coupling of BES at DC link is reported in [9,10]. A two-stage SECS with the indirect coupling of BES via a bidirectional DC/DC converter at. Fig. 1 depicts a block schematic of the specified system. This part delves into the detailed analysis of the presented system control approach, including the systematic designing of controller parameters in the frequency domain based on stability criteria. The presented control strategy is divided into two categories. The details of each category a.
