Tracking power photovoltaic system with sliding mode control strategy

The energy extracted from solar photovoltaic (PV) or solar thermal depends on solar insolation. For the extraction of maximum energy from the sun, the plane of the solar collector should always be normal to the incident radiation. The diurnal and seasonal movement of the earth affects the radiation intensity received on the solar collector. Sun trackers move the solar collector to follow the sun trajectories and keep the orientation of the solar collector at an optimal tilt angle. Energy efficiency of solar PV or solar thermal can be substantially improved using solar tracking system. In this work, an automatic solar tracking system has been designed and developed using LDR sensors and DC motors on a mechanical structure with gear arrangement. Two-axis solar tracking (azimuth angle as well as altitude angle) has been implemented through microcontroller based sophisticated control logic. Performance of the proposed system over the important parameters like solar radiation received on the collector, maximum hourly electrical power, efficiency gain, short circuit current, open circuit voltage and fill factor has been evaluated and compared with those for fixed tilt angle solar collector.

Design, development and performance test of an automatic two-Axis solar tracker system

This article present an application of sliding-mode control strategy to track maximum power of photovoltaic pumping system based on an induction generator with direct torque control. With the maximum power point tracking control system, it is necessary to measure the photovoltaic (PV) panel array output power and to change the duty cycle of the DC/DC converter control signal. To test the robustness of this control, we have compared the results with those obtained using the perturb and observe method. To control the stator flux and electromagnetic torque of of induction machines, the direct torque control is applied. The performance of the proposed system is validated in the MATLAB/Simulink environment (The MathWorks, Natick, Massachusetts, USA) and obtained results confirm the effectiveness of this strategy under the parameter variation environments.

Application of Direct Torque Control to a Photovoltaic Pumping System with Sliding-mode Control Optimization

In this paper, a control of a photovoltaic system connected to the grid is presented. The main components of the studied system are solar arrays connected through a DC bus to a grid side inverter. Due to the instantaneous changes of solar irradiance and temperature, maximum power point tracking (MPPT) is integrated in the inverter control. The energy generated by the grid photovoltaic system is sent to the grid. This is accomplished through an efficient DC/AC conversion where the MPPT is integrated in the inverter to control active and reactive power level injected to the grid. To overcome undesirable drawbacks of hysteresis current control, and to obtain a constant switching frequency, in this paper we applied a modulated hysteresis control. The obtained results using Matlab/Simulink are presented and discussed.

Control of a grid connected photovoltaic system

Dual-axis sun tracker sensor based on tetrahedron geometry

Solar panels are power sources in photovoltaic applications. Solar panels I-V curves depend on environmental conditions such as irradiance, temperature, load and degradation level. In this paper, design and implementation of simultaneous fuzzy-based maximum power point tracker (MPPT) and sun tracker are presented for deployable solar panels. A digital controller was implemented by an AVR microcontroller. Results showed that the proposed system ensure to have photovoltaic system with higher efficiency. Finally, we observed that, using the proposed fuzzy-based MPP tracking and sun tracking simultaneously, solar panel output power can be remarkably increased leading in turn to reduction of the size, weight and cost of solar panels in photovoltaic systems.

S. Karbasian

Papers

Combination of Fuzzy-Based Maximum Power Point Tracker and Sun Tracker for Deployable Solar Panels in Photovoltaic Systems