Control enhancement of power conditioning units for high quality PV systems

This paper presents an adaptive fuzzy-proportional integral derivative (PID) controller for DC–DC boost converters used as voltage regulators in PV systems. This proposed controller maximizes the stable operating range by tuning the PID parameters ultimately at various loading conditions. Then, a fuzzy logic approach is used to add a factor of intelligence to the controller such that it can move among different values of proportional gain (Kp), integral gain (Ki) and derivative gain (Kd) based on the system conditions. This controller allows optimal control of boost converters at any loading condition with no need to retune parameters or possibility of failure. Moreover, the paper presents a novel technique to move between the PI and PID configurations of the controller such that the minimum overshoot and ripple are obtained, which increases the controller applicability for utilization in PV systems supplying sensitive loads. A PV system with a capacity of 1 kW has been simulated and implemented in hardware to examine the proposed controller. Furthermore, this paper discusses the loading limitations in PV systems resulting from switching the power electronic interfaces and transients associated with large loads. These conditions derate the power generation capability of the PV system. We propose some methods to enhance the loadability of these systems under both steady state and dynamic operations. A PV system for home application purposes, with a rated power of 280 W was designed and built to investigate the loadability issue. The proposed enhancements were applied to the experimental setup and the obtained results verified the effectiveness of the proposed methods. © 2012 Elsevier B.V. All rights reserved.