A Voltage PID Controller Synthesis Based on a New Small-Signal Linear Model to Enhance the Performance of the Standard P &O Algorithm Employed in Photovoltaic Panels

Improved P&O-MPPT strategy based on new design of small-signal model used for voltage regulation of solar

“…where 𝑘 𝑑𝑐 is the transfer function gain of the linear small signal model where this last one includes 𝑚 zeros 𝑧 𝑖 and 𝑛 poles 𝑝 𝑖 where 𝑚 ≤ 𝑛. According to several previous works [13,5,11,12], the tuning success of the controller-parameters depends mainly on the model accuracy, given from modeling the actual solar system behavior at STC [14]. Unfortunately, it is quite rare to find a perfect linear model in most real-world applications due several reasons.…”

“…Alternatively, the choice of a large fixed step leads to an acceleration of the convergence speed that is required to track the desired MPP, but it dramatically reduces its accuracy [5]. This generates the ripple phenomenon in the electrical quantities characterizing the energy conversion chain, which results in the loss of a large amount of available energy [5]. As a result, the standard P&O-MPPT control strategy employing the fixed step size seems to fail when it is faced with the challenge of finding a trade-off between MPP tracking in steady state and its convergence speed in transient state when the weather conditions change rapidly [5,8].…”

“…This generates the ripple phenomenon in the electrical quantities characterizing the energy conversion chain, which results in the loss of a large amount of available energy [5]. As a result, the standard P&O-MPPT control strategy employing the fixed step size seems to fail when it is faced with the challenge of finding a trade-off between MPP tracking in steady state and its convergence speed in transient state when the weather conditions change rapidly [5,8]. To overcome this shortcoming, the standard P&O-MPPT control strategy must contain a variable step size instead of a fixed one.…”

“…First, the nonlinear current-voltage characteristic describing the PV cell behavior must be found. It must then be linearized to identify the relationship between the PV voltage and the PV current at standard test conditions (STC) [5,12]. This relationship becomes critical for the remaining part of this procedure.…”

“…Also, because the required linear model necessitates the suppression of continuous terms and second order variations that appear in electrical quantities of the non-linear model. It should be noted that the same small-signal linear model was also be designed graphically in [5] via Matlab ® /Simulink TM software, which avoids all previous analytical computations. However, this modelling procedure does not allow describing some nonlinear and neglected dynamics that existing in practice where the corresponding blocks are not yet available in Matlab ® /Simulink TM package library.…”