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• A new distributed MPPT for three-phase grid-connected cascaded MLIs is presented. • The proposed distributed MPPT method is depending on the phase-shift PWM. • A compensation method is proposed to solve the unbalance problems due shading. The modularity and decreased filter size properties have made cascaded multilevel inverters (MLIs) more applicable than conventional two-level inverters, especially in high and medium power photovoltaic (PV) applications. However, partial shading of PV modules will affect negatively the output power of the unshaded modules. There are several existing solutions in the literature to address this challenge, however almost all of them suffer from complex implementations, low efficiency, and high cost. This paper presents a new simplified feedforward distributed maximum power point tracking (MPPT) method for three-phase grid-connected cascaded MLIs. The cascaded MLI provides a modular, and highly efficient single stage power conversion for PV systems. The proposed distributed MPPT method is depending on the phase-shift pulse width modulation (PS-PWM) method with a simplified implementation. The proposed method is developing a feedforward signal that is proportional to the maximum power of the individual module. Then, the current controller, and the modulating signal are multiplied with the proportionality factor of the module maximum power. Furthermore, a modified modulation compensation method without using proportional-integral (PI) controllers is introduced to solve the problem of the unbalanced three-phase PV output currents that results from PV power mismatches and shading. A case study is implemented for 15 kW PV system to investigate the performance of the proposed method. In addition, comprehensive comparisons with the previous attempts in the literature are provided to verify the superior performance of the new proposed control method. [ABSTRACT FROM AUTHOR]

• The proposed method is general and can be applied to any MLI topology with n number of levels. • The proposed algorithm can be adapted to enhance a single or multiobjectives based operating points. • The proposed algorithm does not need for complex calculations and/or extra hardware. This paper presents a design and an implementation of a generalized adaptive multi-objectives Space Vector Pulse Width Modulation (SVPWM) algorithm for multilevel inverters (MLIs). SVPWM is considered as an influential and resilient tool for optimizing the performance of MLIs. Innumerable objectives can be attained by the proper selection of switching times and states. The performance of MLIs can be improved, as well. Hitherto, achieving multiple objectives could be a challenging mission in the SVPWM algorithms scheming. In this paper, an objective function has been demarcated based on the weighted sum of the desired performance parameters. Then, considering this chosen objective function, the proposed algorithm nominates the optimum switching sequence from valid switching sequences. With this algorithm, the objective function can be weighted for the sake of reaching different performance parameter combinations; to outfit different applications and operating points. Furthermore, different SVPWM design cases for enhancing the operation of MLIs can be accomplished. Voltage balance over the DC-link capacitors in MLIs has been implemented, as a study case, using the proposed SVPWM. Both simulation and experimental platforms have been utilized. The results visibly illustrate the generality of the proposed algorithm, and it can improve different performance limitations of MLI such as; achieving a fast balance of the capacitors voltages with reduced power losses. The selected case study has achieved 21.62% faster voltage balance with 17.61% reduction in the power losses compared to conventional SVPWM method. Notwithstanding its straightforwardness to be implemented without complex calculations, the proposed algorithm can maintain the high operating efficiency of the MLI system for a wide range of operation. [ABSTRACT FROM AUTHOR]

In this paper, an improved design approach for fuzzy logic control (FLC) systems is proposed for MPPT control of PEMFCs. The proposed design is based on the recent Equilibrium Optimizer method for determining the optimum parameters to fully benefit the inherent flexibility and freedom of FLC systems in addition to achieve fast and accurate tracking. During the optimization process, gains of membership functions of FLC is used as a decision variable, whereas the integral of error is used as a cost function. The obtained results are compared with particle swarm optimization (PSO), genetic algorithm (GA), electric charged particles optimization (ECPO) and spotted hyena optimizer (SHO). The proposed EO methodology outperformed all other methods, achieving the best mean, median, variance, and standard deviation. Moreover, statistical tests including Wilcoxon, Holm-Bonferroni correction, Kruskal Wallis, and Friedman tests are performed to prove efficiency of the proposed strategy. In last, different scenarios of changing operating temperature and water content are used to prove the reliability of the optimized FLC. The obtained results are compared with conventional FLC and hill-climbing method. The main findings confirm that the proposed design using combined features of EO and FLC presents a promising solution for MPPT in PEMFCs. • An improved design approach for FLC system is proposed for MPPT control of PEMFCs. • The proposed design is based on the recent Equilibrium Optimizer. • The proposed FLC method represents a variable step size MPPT control method. • The combination of FLC with the EO method results in optimizing the design of FLC MPPT. [ABSTRACT FROM AUTHOR]

Model Predictive Control algorithms have been recently developed for controlling grid-tied converters. However, the inclusion of the converter switching constraints in the optimization problem and the high computational burden are some of the main challenges of these algorithms. In this way, this paper proposes a Fast Finite Control Set Model Predictive Control algorithm with a low computational burden for a three-phase Neutral Point Clamped inverter considering its switching constraints. Initially, the vector with the unconstrained solution in the line-to-line voltage coordinates is obtained to minimize the current tracking error. Then, it is limited to ellipses as an intermediate step to ensure that the selected voltage vector is feasible and to restrict the switching transitions. The constrained vector is rounded to the nearest inverter line-to-line voltage vector to be implemented in the next sampling period. The NPC redundant phase-voltage vectors are generated online to avoid the potentially destructive switching transitions. The neutral point is balanced by minimizing a cost function, considering the obtained redundant phase voltage vectors, and is evaluated at most twice in each sampling period. As both control objectives are treated in a cascaded sequence, the proposed Fast FCS-MPC avoids the design of weighting factors and has the advantages of low computational burden, fast transient response, and good steady-state performance. Finally, Hardware-in-the-Loop results are presented to compare the proposed Fast FCS-MPC to other strategies presented in the literature, and the effectiveness of the proposed algorithm is also demonstrated by means of an experimental prototype. • System model in the converter output line-to-line voltage space with integer vectors. • Inverter constraints included in the formulation of the optimization problem. • Fast way to obtain the switching voltage vector by rounding the constrained solution. • Comparison results indicating equivalent performance with optimal algorithms. • Lowest computational burden when compared to similar algorithms. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reliability and security of test network are improved using inverter-based PVs. • DSTATCOM functionality associated with the interfacing inverters of PVs are proposed. • PVs allocation as well as weight factors are optimized. • Seasonal stochastic uncertainty of load demand and PV output power are considered. • MCS as well as SBR methods are used for modelling the stochastic uncertainty. Photovoltaic (PV) generation systems have become popular renewable energy alternatives for facing climate changes and for promoting energy transition. During the low/absence of PV output power, the addition of distribution static synchronous compensator (DSTATCOM) functionality to PV inverters represents an important target for maximizing the benefits from inverter capacity. The novelty of this present work is improving the reliability and security indices of the distribution network using an optimal integration of inverter-based PVs without and with their inherent DSTATCOM functionality under uncertain load demand and PV output power. A wide evaluation of reliability performance indices including the load-oriented and customer-oriented reliability indices in addition to the network security-index (NSI) is investigated. Monte Carlo Simulation (MCS) and the scenario-based reduction (SBR) methods are implemented for predicting the stochastic behavior of different uncertainty sources. The IEEE 33-bus test network is used for verifying the superiority of the proposed method by considering various seasonal loading. In addition, the impacts of protective devices installation as well as the linear failure rate of feeders on the reliability indices are addressed. The results and comparisons show superior enhancement of reliability and security indices of distribution test network using inverter-based PVs with their enabled DSTATCOM functionality. [ABSTRACT FROM AUTHOR]