Differential power processing architecture for increased energy production and reliability of photovoltaic systems

Abstract

Conventional energy conversion architectures in photovoltaic (PV) systems are often forced to trade off conversion efficiency and power production. This paper introduces a power processing architecture that enables each PV element to operate at its maximum power point (MPP) while only processing a small fraction of the total power produced. This is accomplished by providing only the mismatch in the MPP current of a set of series-connected PV elements. The differential power processing architecture increases overall conversion efficiency and overcomes the challenges of unmatched MPPs (due to partial shading, damage, manufacturing tolerances, etc.). Local control of the differential converters enables distributed protection and monitoring. The reliability analysis included in this paper shows significantly increased overall system reliability. Simulation and experimental results are included to demonstrate the benefits of this approach.

Analysis and Design of 4-to-1 Capacitor-Stacking Balancer for Stacked Voltage Domain

“…The analysis and design of the CSB including time-domain Matrix switch set OUT [1:4] IN [1:4] OUT [1:4] IN [1:4] OUT [1:4] operation, voltage equation, and the dead-time effect are explored. Note that although the observations on the current imbalance as discussed in the previous works [8], [23], are only partly addressed, this study provides analytical models that predict the results for a generic case. In Table I, this study is compared with recent previous studies [6], [8], [19], [23], [34], [37].…”

“…Although the stacked system has the above list of advantages [18], [22], a converter in SVD is required to balance the voltages and currents between cores to operate the stacked system properly. In the case of the differential power processing (DPP) [6], [23], [24], a converter is proposed and analyzed to satisfy the maximum power point tracking (MPPT) of the system in a stacked structure. The structure this study used the most is one in which a stepdown converter is chained by using voltage generated from upper and lower adjacent cores.…”

A novel switched-capacitor topology for submodule level maximum power point tracking under partial shading and mismatch conditions

“…But the switches used in PV-to-bus converters must be rated to bus voltage and this brings some disadvantage from the application point of view. In [11]- [12] a local control strategy requiring the current and voltage measurement data is developed for the bidirectional buck-boost converter employed as a DPP in the PV-to-PV architecture proposed by [10]. A basic perturb and observe algorithm run on the local controller tries to maximize the power of each PV element finding the corresponding duty cycles.…”

Design and evaluation of a modular resonant switched capacitors equalizer for PV panels

“…Hence, the parallel circuitry only needs to equalize the panels' voltages, while the global MPPT can be carried out by a central inverter, which is fed by the string of the PV panels [6]. Voltage equalization can be carried out by converters that are fed from the output of the PV array [5,6] or by equalizing adjacent panels [9,10]. The latter has a number of advantages such as being self contained and hence shorter interconnections and a lower voltage on the switches.…”

“…The downside of the localized equalizer approach is the fact that the equalizing current needs to propagate from one module to another to replenish the missing current in the shaded panel and this may increase the losses due to the longer conduction path. The adjacent panels equalization approach has been previously studied using a buck-boost converter [9,10]. The present study explores an alternative method for adjacent panels equalization using a switched capacitor converter (SCC).…”