In this paper, power-sharing management control on an AC islanded microgrid is investigated to achieve accurate reactive power sharing. The droop control method is primarily used to manage the active and reactive power sharing among the DGs in the microgrid. However, the line impedance mismatch causes unbalanced reactive power sharing. As a solution a consensus-based adaptive virtual impedance controller is proposed, where the consensus algorithm is used to set the reactive power mismatch; then a virtual impedance correction term is generated through a proportional-integral controller to eliminate the line impedance mismatch. Thus, reactive power sharing is achieved without knowledge of the line impedances or using a central controller. Moreover, the consensus algorithm is used to restore the AC bus voltage to the nominal value by estimating the DGs average voltage using neighbor communication to compensate for the decreased magnitude of the voltage reference. Matlab/Simulink is used to validate the accuracy of reactive power sharing and voltage restauration achievement of the proposed solution through simulation of different scenarios. In addition, a dSPACE DS1104 is used within a developed experimental testbench based on two parallel DGs to validate the effectiveness of the proposed solution in the real world.
<p>In this paper, an optimization of PV grid connected system is investigated. This is achieved by considering the application of artificial intelligence in the DC side to realize maximal power extraction, and using a sine-band hysteresis control in the AC side of the system, to generate a sine current/voltage suitable for grid connection IEEE929-2000 standards. The overall system has been simulated taking into account environmental effects and standards constraints in order to achieve best performance. The choice of sine band hysteresis control was selected considering its implementation simplicity. The algorithm runs fast on a low-cost microcontroller allowing to avoid any delay that can cause a phase shift in the system. An experimental setup has been realized for tests and validation purposes. Both simulation and experimental results lead to satisfactory results which are conform to the IEEE929-2000 standards.</p>
The water electrolysis process requires a high DC current supply that can sustain the desired hydrogen production rate over a large period of operation at a competitive cost. During the conversion of electricity from AC to DC, power quality may be affected because of the non-linear effect caused by the power electronics. Most of the recent research has focused on exploring different rectifier topologies. None of them have investigated the influence of cell stack degradation on the performance of power electronics. In this work, we built a one-way interaction model to predict the influence of electrolyzer degradation on power electronics output over multiscale operational time (from milliseconds to years) for proton exchange membrane electrolyzer (PEM). In this model, we assume a constant degradation rate on the electrolyzer that results in a linear increase of internal resistance over time. Counterintuitively, rather than the power quality decreasing, results show that the power quality increased with the electrolyzer degradation for both the AC (power factor and THD) and DC side (ripple) for the 6-pulse thyristor. Furthermore, the influence of three variables (degradation rate, load current, and topology) on AC (power factor and THD) and DC (ripple factor) side power output were investigated. Finally, results were partially validated with experimental data from a 20 MW scale PEM electrolyzer.
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