Analysis, Modeling, and Control of a Stand-alone Photovoltaic Generation System

This paper presents a control scheme and transient model for a voltage source DC-to-DC converter acting as the DC link interface for photovoltaic array. The control scheme provides for Maximum Power Point Tracking (MPPT) technique on the Photo voltaic array while maintaining a constant DC link voltage that can be tied to an energy storage system and/or a voltage source converter DC-to-AC converter. A non-linear voltage source was implemented in Alternative Transients Program (ATP) to model a Photovoltaic array under varying solar irradiance and temperature conditions. Due to the dependency of PV generation upon weather conditions, the maximum power point tracking (MPPT) technique is important since it makes the PV generation system provide its maximum power. MPPT can be implemented with several algorithms, but this paper deals with the Incremental Conductance (INC-CON) for the following: no oscillations at maximum point, high response, and high stability under rapidly changing in atmospheric conditions. The only disadvantage is its complexity in the control circuit. The paper will show successful implementation of an incremental conductance MPPT algorithm controlling a boost DC-to-DC converter in Alternate Transients Program (ATP). This model can be used to study further refinements to boost converter, or could be coupled with a DCAC converter model to simulate a full grid-tied PV power generation system. Such a model would be useful for fault and power flow studies related to variable PV generation systems.