Granular control of photovoltaic arrays by means of a multi‐output Maximum Power Point Tracking algorithm

Abstract

In this paper, a Distributed Maximum Power Point Tracking (D‐MPPT) approach in photovoltaic (PV) applications is discussed. The proposed control method is suitable for the granular control of the PV generator at a module level or even at a sub‐module level. D‐MPPT is usually implemented by means of independent converters, each one of them running its own MPPT algorithm. Instead, the architecture proposed in this paper consists of only one digital controller, implementing a multivariable MPPT algorithm based on the Perturb and Observe approach, acting on a number of dc/dc converters, each one of them dedicated to a single PV module. The proposed control strategy reduces the number of current sensors with respect to the classical D‐MPPT architecture and tracks the maximum power evaluated at the dc/dc converters' output. Planar solid immersion mirror simulations and experimental results confirm the validity of the approach and of the design guidelines proposed in the paper. Copyright © 2012 John Wiley & Sons, Ltd.

Sliding-Mode Controller for Maximum Power Point Tracking in Grid-Connected Photovoltaic Systems

“…Energies 2015, 8,  At the right of the MPP (voltages higher than ) the transversality condition is also fulfilled.  At the MPP ( ) the transversality condition is not fulfilled.…”

“…From such an expression, the proposed switching function Ψ and sliding surface Φ , given in Equation (8), are defined:…”

“…Then, the state-space model of both the PV system and SMC is formed by the simultaneous Equations (1)- (3) and (8). The relations within such a state-space model are illustrated in the block diagram of Figure 5, which put in evidence the signals processing and variables exchanged between the PV system and the SMC: the PV system disturbances are the short-circuit current (defined by the irradiance and temperature) and the load voltage; the control signal u is generated by the SMC on the basis of the PV current and voltage; and the SMC derives both the PV voltage and current to construct the switching function.…”

“…[7]. Two of the most commonly used MPPT techniques are Perturb and Observe (P & O) and Incremental Conductance (IC); the reason for this popularity is its implementation simplicity and its relatively good performance [4,8]. Other MPPT techniques are based on using fractional values of the open circuit voltage and short circuit current, i.e., the Fractional Open Circuit Voltage and the Fractional Short-Circuit Current.…”

“…Such mitigation is traditionally performed by using large electrolytic capacitors for C b , however the electrolytic technology introduces reliability problems due to its high failure rate [14]. Then, the Energies 2015, 8, voltage regulator in Figure 2 enables to mitigate the voltage oscillations in the DC-link produced by small non-electrolytic capacitors, thus improving the system reliability [3,14]. Figure 2.…”