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Enhancing the PV power requires necessity to track the MPP robustly. Most techniques implemented to obtain MPPT have some drawbacks, one of them is the oscillation around the operating point. This paper suggests sliding mode control technique to minify this problem. The strategy of SMC is designing a sliding surface which set the operating point. Reaching this surface in finite time requires control law applied to the DC/DC converter gate. The PV peak power can be obtained smoothly at different conditions by changing the duty cycle of converter. The PV connected with grid via multilevel inverter. To prove the stability of the SMC comparison between P&O and SMC methods was done. SMC has low transient under sudden variation and reach the steady state point faster than P&O. The simulation results are implemented in SIMULINK. The results confirmed the robustness, good performance of SMC strategy at different environmental conditions. [ABSTRACT FROM AUTHOR]

The partial shading is one of most critical problems facing the Maximum Power Point Tracking (MPPT) techniques for photovoltaic systems. This paper provides a review of challenges and opportunities regarding the problem of partial shading. In addition, it introduces a new technique for tracking the Global Maximum Power Point (GMPP) under different Partial Shading Conditions (PSC). The technique utilizes a two-stage algorithm to accomplish the tracking process efficiently. In the first stage, it applies a Genetic Algorithm (GA) to get the nearest point to the GMPP. In the second stage, it utilizes a new and fast MPPT algorithm to search for the target GMPP starting from the nearest point fetched in step one. In order to evaluate the new technique, a complete microcontroller based prototype is implemented and tested. The experimental results show that the new technique reaches directly to the GMPP in very short time and with limited steady state oscillations. Accordingly, the new technique has a significant improvement in energy extraction efficiency from the photovoltaic array to the load. [ABSTRACT FROM AUTHOR]

Grid connected photovoltaic (PV) system encounters different types of abnormalities during grid faults; the grid side inverter is subjected to three serious problems which are excessive DC link voltage, high AC currents and loss of grid-voltage synchronization. This high DC link voltage may damage the inverter. Also, the voltage sags will force the PV system to be disconnected from the grid according to grid code. This paper presents a novel control strategy of the two-stage three-phase PV system to improve the Low-Voltage Ride-Through ( LVRT ) capability according to the grid connection requirement. The non-linear control technique using Improved Particle Swarm Optimization ( IPSO ) of a PV system connected to the grid through an isolated high frequency DC–DC full bridge converter and a three-phase three level neutral point clamped DC-AC converter ( 3LNPC 2 ) with output power control under severe faults of grid voltage. The paper, also discusses the transient behavior and the performance limit for LVRT by using a DC-Chopper circuit. The model has been implemented in MATLAB/SIMULINK. The proposed control succeeded to track MPP, achieved LVRT requirements and improving the quality of DC link voltage. The paper shows superiority of IPSO than Incremental Conductance (IC) method during MPPT mode of PV system. [ABSTRACT FROM AUTHOR]