Two-stage Photovoltaic Power Research Articles

WITHDRAWN: Constant power generation in single and two stage PVPPS with CPG and MPPT modes of operation

Abstract Photovoltaic Power Plants (PVPPs) functions through the tracking of maximum power point with a view for maximizing the conversion efficiency of the power plants. Grid voltage disturbances, over voltages overloading etc., are some newer challenges faced by the power system operators while operating this photovoltaic power plants. Maximum Power Point Tracking (MPPT) algorithm and Constant Power Generation (CPG) algorithm are used for obtaining maximum output voltage from these power plants. Often the output voltage of the PVPPs varies according with the grid disturbances, overloading and overvoltage conditions. The MPPT and CPG algorithms are introduced in these power plants to stabilize the output voltage levels. This paper of study encapsulates a single algorithm for gaining a maximum stable output voltage with less oscillation and which gives a fast dynamic response. This algorithm is formed by the combination of both MPPT-Perturb and Observe and CPG algorithms (MPPTPO-CPG). This algorithm would be suitable enough to get a constant power output from the Photovoltaic Power Plants (PVPPs) and is suitable for both single-stage and two-stage Photovoltaic Power Plants. The MPPT algorithm is utilized for fetching the maximum power output from the PVPPs. Maximum output voltage; fast dynamic response and higher oscillation are gains of using the MPPT algorithm. Output voltage is destabilized during higher oscillation and hence constant power generation algorithm is introduced, which gives low oscillation and maximum power output, but the dynamic response is slow. Hence these two algorithms are combined to a new algorithm that provides maximum output voltage, efficiency and a fast dynamic response. The boost converter is the eminent component used in the proposed system for achieving CPG and MPPT control.

Grid connection technique based onμtheory for a two‐stage PV structure

There is greater flexibility in selecting the direct-current (DC) bus voltage in a two-stage photovoltaic (PV) grid-connected structure than in a single-stage one. The independent DC/DC and DC/alternating current (AC) control in traditional control methods changes the duty cycle of the first-stage DC/DC, which affects the control of the secondary DC/AC and even stabilises the DC bus voltage between the two stages. Therefore, two-stage converters should be considered and controlled in a unified manner. Here, the authors introduce a robust μ value control method based on the hybrid sensitivity theory to control a two-stage PV power generation system. Considering the effect of parameter perturbation on the modelling of the DC/DC average state model, the proposed method improves the DC bus voltage stability of a PV system and the power quality of the grid-connected current while achieving the maximum power point tracking performance of the PV. MATLAB simulations using three PV operating conditions demonstrate that the proposed control method can effectively reduce the fluctuation of the DC bus voltage between the two stages, the harmonic distortion rate of the grid-connected current, and the power oscillation time when the working conditions change.

Adaptive noise cancellation based harmonic elimination in grid integrated photovoltaic system

In this study, an adaptive noise cancellation technique is applied to eliminate harmonics in a grid integrated solar photovoltaic (PV) system under non-linear load. A neuron is used to extract a fundamental component from polluted load currents. The proposed system serves multiple functions, as improvement of power quality at point of common coupling including other connected non-linear loads, extraction of maximum power from a given PV array and feeding extracted solar power into the distribution system. The multiple functionality at a time helps in fast recovery of cost of power converters. The proposed control algorithm is based on adaptive detection of fundamental component. The proposed control algorithm presents an improved sensitivity for fast load changes. This proposed two-stage PV power generating system is designed, modelled and tested to provide the solutions of several power quality problems in three-phase four-wire distribution system.