With the global consciousness of climate change, renewable energy systems are prioritized over the conventional energy systems. The deep injection of renewables into the power systems is creating several challenges to the grid due to wide variations in their output power depending on the time of the day, weather etc. Of these challenges, frequency change plays a vital role in maintaining the power quality. This paper presents a novel sliding mode controller with non-linear disturbance observer to effectively mitigate the wide changes in the frequency. A sliding mode surface based on estimated disturbance along with states is designed. A sliding mode control law is proposed to compensate disturbances including variations in renewables, load and parameters under mismatched uncertainties. The proposed observer based controller is tested for three area multi-machine power system in MATLAB/Simulink. The simulated results proved to alleviate the frequency variations effectively compared to the conventional controllers.

Higher penetration of variable renewable energy sources into the grid brings down the plant load factor of thermal power plants. However, during sudden changes in load, the thermal power plants support the grid, though at higher ramping rates and with inefficient operation. Hence, further renewable additions must be backed by battery energy storage systems to limit the ramping rate of a thermal power plant and to avoid deploying diesel generators. In this paper, battery-integrated renewable energy systems that include floating solar, bifacial rooftop, and wind energy systems are evaluated for a designated smart city in India to reduce ramping support by a thermal power plant. Two variants of adaptive-local-attractor-based quantum-behaved particle swarm optimization (ALA-QPSO) are applied for optimal sizing of battery-integrated and hybrid renewable energy sources to minimize the levelized cost of energy (LCoE), battery life cycle loss (LCL), and loss of power supply probability (LPSP). The obtained results are then compared with four variants of differential evolution. The results show that out of 427 MW of the energy potential, an optimal set of hybrid renewable energy sources containing 274 MW of rooftop PV, 99 MW of floating PV, and 60 MW of wind energy systems supported by 131 MWh of batteries results in an LPSP of 0.005%, an LCoE of 0.077 USD/kW, and an LCL of 0.0087. A sensitivity analysis of the results obtained through ALA-QPSO is performed to assess the impact of damage to batteries and unplanned load appreciation, and it is found that the optimal set results in more energy sustainability.

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Electric vehicles (EVs) have various advantages over traditional internal combustion engines (ICEs), including reduced carbon emissions, greater energy efficiency, and a lessened reliance on petroleum supplies. The use of EV charging infrastructure and power levels are reviewed in this article. Battery performance is affected by the design of the battery as well as the charger parameters and infrastructure. In this paper, the off-board and on-board charging methods with bidirectional and unidirectional power flow are compared. Hardware restrictions and connectivity concerns are eased with a unidirectional charger. The bidirectional charger enables both battery energy injection back into the grid and the vehicle. Power is constrained by the onboard charger due to its size, weight, and price. Both conductive and inductive onboard chargers are viable. For high current rates, which are not supported by EVs, it is feasible to develop an off-board charger. The time required for charging, amount of power, cost, equipment, location, infrastructure configurations, and other parameters are provided, compared, and reviewed for different power level chargers, such as level-1 (slow), level-2 (semi-fast), and level-3 (fast).

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