Renewable Energy, Vol.97, 689-696, 2016
Cascade closed-loop control of solar trackers applied to HCPV systems
High concentration photovoltaic (HCPV) modules require a high precision tracking system for reaching their highest conversion efficiency. One way to accomplish this goal is by using a closed-loop mechanism and a sun sensor to track the sunlight. This paper proposes a cascade control algorithm capable of achieving a sun tracking error of 1' for its application in high concentration photovoltaic systems. The algorithm follows an inner loop-outer loop topology. The inner loop employs a Nonlinear Proportional Proportional Integral (NP-PI) controller and the outer loop resorts on a Proportional Integral (PI) controller. A tuning procedure for setting up the cascade controller is also described. Experiments on a laboratory prototype compare the performance of the proposed cascade controller with a PI controller not resorting on an inner loop. These outcomes show that the proposed control law provides improved tracking accuracy with less actuator wear. (C) 2016 Elsevier Ltd. All rights reserved.
Keywords:Solar energy;Solar tracking;High concentration photovoltaics;Cascade control;PID control;Real-time motion control