Uniform Dynamic Control for Nonlinear PV Power Systems via Small-Signal Modeling

Abstract

This paper proposes a Uniform Dynamic Control (UDC) strategy to ensure consistent dynamic performance in nonlinear photovoltaic (PV) power systems. Conventional Static Gain Control (SGC), which applies fixed controller parameters, often results in bandwidth variation and undesired transient behavior due to the nonlinear voltage-power characteristics of PV arrays and their sensitivity to irradiance and load variations. These limitations become more critical in single-stage systems, where the lack of energy storage directly couples PV voltage to load dynamics. To address this, a small-signal model is developed to characterize the PV system's operating-point-dependent behavior and is extended to capture the coupled dynamics between PV voltage and load-side rotor speed in motor-driven applications. Based on this model, UDC adaptively tunes the controller gains to maintain uniform control bandwidth and consistent transient response across a wide range of conditions. Experimental validation confirms that the proposed UDC improves voltage regulation, enhances speed response uniformity, reduces transient deviations and also verifies that the developed small-signal model accurately captures the system's dynamic behavior.