Design of a Gain Scheduling Photovoltaic Energy Conversion System

摘要

In this paper, a gain scheduling perturbation and observation (P&O) algorithm is proposed to realize the dynamic and rapid maximum power point tracking (MPPT) for a grid-connected photovoltaic energy conversion system (PECS). The hardware implementation of the PECS consists of a 1.5kW (at 500V) monocrystalline silicon photovoltaic (PV) array and a voltage-sourced inverter (VSI) whereby an IGBT-based intelligent power module is applied. In order to reach MPPT, the reference dc-link voltage of the VSI is generated by a command generator based on conventional P&O algorithm. To further improve the performance of the PECS under various daylight irradiations, the control gains for command generator are scheduled according to the gradient of electrical characteristic of the PV array exposed to a daylight irradiation. In contrast to the use of the MPPT algorithm in electrical power conversion, the reactive power compensation is also feasible to improve the power factor for the grid utility under low irradiation and thus increases the facility utilization significantly. The experimental results show that the proposed PECS with gain scheduling P&O algorithm is capable of tracking maximum power point and compensating the reactive power for the grid utility.