Conventional and modified MPPT techniques with direct control and dual scaled adaptive step-size

Conventionally, for adaptive MPPT change in power over change of voltage (dP(PV)/dV(PV)), change in power over change of current (dP(PV)/dI(PV)) or change in power over change of duty (dP(PV)/dD) had been utilized for variable stepping. However, this paper presents dual scaled adaptive step sizing, depending on change of power (dP(PV)). This technique reduces complexity, improves transient and dynamic response to sudden irradiance changes. As, PV characteristic curve has two different slopes, one at the left and the other at the right of MPP. Nevertheless, a constant fine-tuned scaling factor for operation at left of MPP may cause overshoot or undershoot at right side of MPP. Similarly, constant scaling factor offering good performance at right slope of the MPP may give slow voltage response when the system operates at left of MPP. Therefore, dual scale adaptive technique dependent on change of power (dP(PV)) has been proposed to attain credible performance at both sides of the slope. This technique has been employed on conventional and modified MPPT schemes with direct control, explicitly on modified Incremental Conductance (IncCond) method. Further, the aim is to establish the fact that even with direct implementation, IncCond remains a specific implementation of P & O, by comparatively analyzing the performance of each method. Simulation and experimental results authenticate the validity of the proposed scheme.