A system simulating the output voltage-current characteristics of a photovoltaic array is described. The simulator may be used to test the performance of PV arrays and associated power conditioning equipment necessary for the autonomous or interconnected operation of photovoltaic energy sources. The simulator's main features include simplicity of construction, wide parametric variability and low cost. It is capable of reproducing the output characteristics of commercially available arrays at varying solar irradiation levels with sufficient accuracy. The design ensures the lowest possible power dissipation and minimal thermal drift. It is estimated that the cost of the simulator is an insignificant fraction of the actual array cost in the kilowatt power range.

A Photovoltaic Array Simulator

This paper is concerned with the conceptual design and realization of matching networks for the continuous transfer of maximum power from a non-linear source with randomly varying characteristics to a load. Such sources are commonly encountered in the use of photovoltaic arrays or wind energy conversion systems for the production of electric power. Experimental studies as well as computer simulation results verify the validity of the design and point to methods for its practical implementation.

Maximum power transfer in non‐linear source‐load systems

This paper describes the development, design, and operation of an electronic device which performs dynamic matching between electric energy sources and their respective loads. This matching is achieved by monitoring the output power of the energy source and modulating a control signal which, in turn, regulates appropriately the operation of a source-load interface device. This device is characterized by a simple structure and an ability to continuously match the characteristics of the source to those of the load, for maximum power transfer, even when these characteristics are randomly time-varying. The device may be used with existing energy systems, without significant changes, and operates effectively even when the utility grid substitutes for the load. Its operation is described in terms of a configuration involving renewable energy sources, such as wind electric conversion systems and photovoltaic arrays, as the primary energy generators. The latter are attracting the growing interest of many investigators recently.

Design of a Power Conditioning Unit for Nonlinear Source-Load Systems

The design and implementation of appropriate power conditioning apparatus for the interconnected operation of PV arrays with the utility grid are presented. Problems of maximum power transfer from the PV array to the utility grid, reliability of the interconnected system operation and component protection are addressed. Because of the intermittent nature of the available solar energy, the need for conversion of dc electrical power to ac and the fluctuating loads of the utility system, optimization methodologies and associated equipment are developed for converting the maximum available solar power to electrical form and transfering it to the grid. A dual methodology is adopted containing a theoretical — system simulation — study of the performance of the interconnected system and a parallel experimental facility for the implementation of the system design. Results indicate higher energy transfer efficiencies in combination with an increased quality and reliability of performance of the PV array — utility grid system.

E. J. Grimbas

Papers

Power Conditioning in Solar Photovoltaic Array Applications