This paper presents a dynamic electrochemical model for representation, simulation, and evaluation of performance of small size generation systems emphasizing particularly proton exchange membrane fuel-cell (PEMFC) stacks. The results of the model are used to predict the output voltage, efficiency, and power of FCs as a function of the actual load current and of the constructive and operational parameters of the cells. Partial and total load insertion and rejection tests were accomplished to evaluate the dynamic response of the studied models. The results guarantee a better analytical performance of these models with respect to former ones with a consequent reduction in time and costs of projects using FCs as the primary source of energy. Additionally, this electrochemical model was tested for the SR-12 Modular PEM Generator, a stack rated at 500 W, manufactured by Avista Laboratories, for the Ballard Mark V FC and for the BCS 500-W stack.

The Primary Goal of this article is to discuss the development of intelligent controls for a power electronic inverter capable of interfacing a photovoltaic (PV)-based unit to the utility grid. The inverter is designed as a single-phase, full-bridge converter operating at 120 V, 60 Hz ac. The control functionalities of the inverter are defined under the perspective of the Smart Grid Initiative (SGI) of the U.S. Department of Energy and substantiated via case studies in this article as the ability to supply real and reactive power to local loads, supply real and reactive power to other utility loads up to the rated capacity of the inverter, provide voltage support at the point of common coupling (PCC), store energy in a lead-acid battery bank, and enable the provision of control options to the consumer based on near real-time electricity information obtained from the utility through advanced metering devices.

In this paper, a dynamic mathematical model to describe the transient behavior of a system of self-excited induction generators (SEIGs) operating in parallel and supplying a common load is proposed. Wind turbines with SEIGs are increasingly being used to generate clean renewable energy in rural areas owing to many economical advantages. Parallel operation of SEIGs is required where the size of the machine is a constraint. SEIGs connected in parallel experience various transient conditions such as generator/load/capacitor switching that are not easy to simulate using conventional models. An automatic numerical solution to predict the steady-state and transient behavior of any number of SEIGs connected in parallel is proposed in this paper. The generators can be of different ratings and can have different prime mover speeds. The performance of the proposed model when subjected to various dynamic scenarios is compared with experimental results. The simulation results are in good agreement with the experimental results, confirming the validity of the proposed model. An aggregated model of a small wind power system is also proposed. This model was applied to a two-wind turbine case, which can be extended to simulate a complete wind generating system.

This paper presents a high frequency AC-based microgrid as an interesting step towards integration of renewable energy sources in a distributed generation system. The successful implementation of an HFAC microgrid depends on the best utilization of the sources and the common bus, which can be accomplished using a unified power quality conditioner (UQPC). The UPQC can compensate for current and voltage harmonics and also for reactive power. Its controller is based on the instantaneous p-q theory and the results obtained so far show that this conditioner can be effectively used to improve the system operation.