Three-phase Grid-tied Photovoltaic System Research Articles

Two-Stage Three-Phase Grid-Tied Photovoltaic System with MPPT Method

This paper examines the transfer of the power generated by the photovoltaic (PV) system to the three-phase alternating current (AC) power grid with maximum efficiency by controlling in two stages. With the designed PV system, it is aimed to transfer the energy received from the source with high efficiency to the network by using the maximum power point tracking (MPPT) method in order to ensure power stability. In addition, with a second control mechanism, the current at the output of the inverter is instantly controlled and the voltage value of the generated power is kept constant. Thanks to this control system, solar energy has been kept under control from electrical energy generation to its transfer to the power grid. In order to predict the quality of the generated power, the total harmonic distortion (THD) rate of the current at the output of the PV system was determined as a result of the simulations made in the computer environment. It is seen that the simulated PV system, according to the values of different solar radiation levels, tends to keep the voltage value of the power to be transferred to the grid constant at the desired level and that the THD value has been reduced below three percent at the time of maximum power generation.

Three-phase grid-tied photovoltaic system with an adaptive current control scheme in active power filter

ABSTRACT In this article, an adaptive normalized least mean fourth (NLMF) control scheme is employed to generate the anti-harmonic currents of photovoltaic (PV) integrated with grid system for harmonic elimination and power factor (PF) correction (PFC). In addition, a fuzzy tuned PID-based adaptive dc voltage regulator is integrated in the proposed scheme to regulate the reference voltage of the dc bus. The proposed FPID-based NLMF control scheme attains the features of power quality (PQ) related issues elimination such as PFC and harmonics elimination with an extraction of photovoltaic (PV) generated maximum power through the grid interfacing converter (VSC) at a unity PF. Moreover, the PV system’s feed-forward (FF) component is included in the control strategy to enrich the aggressive behavior of the system. The NLMF current controller is employed to measure the three-phase calculated currents by extracting the fundamental weight constituents of the load currents for harmonic mitigation in the presence of point of common coupling (PCC). The proposed control topology is developed on MATLAB/SIMULINK software platform under different load and grid transient conditions. A dSPACE based real-time laboratory platform is developed to justify the proposed scheme under different conditions such as steady-state, load dynamic, removed and unbalanced, grid voltage distorted, unbalanced, swell and sag conditions. The presented control scenario’s results are obtained satisfactory and the grid current’s THD are in the IEEE-519 regular limits.

Decoupled Control of Three Phase Grid Connected Solar PV System

A reliable grid connected Photovoltaic (PV) system require effective control schemes for efficient use of solar energy. This paper presents a three-phase grid tied PV system with decoupled real and reactive power control to achieve desired power factor with Maximum Power Point Tracking (MPPT) controller to get maximum solar energy. The synchronous reference frame (dq) control along with decoupling concept is used to control the DC-AC inverter output, while the Phase Locked Loop (PLL) synchronization technique is used to monitor and synchronize the voltage and current at the grid side. The DC-DC converter with Incremental Conductance (InC) based MPPT model is also designed in this paper due to better accuracy compared to Perturb & Observe (P&O) algorithm. The simulation is performed in MATLAB/SIMULINK and a 31.5 kW PV system is modelled to get 30 kW power with the help of MPPT at Standard Test Conditions (STC). Any power factor value between 0.85 lagging to 0.9 leading can be obtained by changingreference q current in this inverter control strategy. The simulation results show that the change of reactive powerdoes not affecttheactive power values of the system, which verifies the effectiveness of the decoupled control strategy of the inverter.

A Fast Fault Identification in a Grid-Connected Photovoltaic System Using Wavelet Multi-Resolution Singular Spectrum Entropy and Support Vector Machine

A new protection scheme based on applying a combination of wavelet multi-resolution singular spectrum entropy and support vector machine is proposed to identify different types of grid faults in a three-phase grid-tied photovoltaic system. In this technique, discrete wavelet transform with multi-resolution singular spectrum entropy is utilized to extract the unique features of three-phase voltage signals at the point of common coupling. The three-phase voltage signals are decomposed to provide detail and approximation coefficients of wavelet transform. Then, various features between different types of grid faults can be extracted by a combination of multi resolution analysis and spectrum analysis with entropy as the output. The constructed features vector is utilized as input data of a support vector machine classifier to identify and classify various types of faults. The results illustrate that the proposed intelligent technique not only recognizes different types of grid faults correctly, but also performs quickly in identifying grid faults in a grid-connected photovoltaic system. Apart from this, a graphical investigation is executed to observe the effects of different types of grid faults in photovoltaic (PV) operation which highlight the necessity of intelligent protection methods to protect PV systems.

Análise Comparativa de Algoritmos de Mppt Bioinspirados nos Lobos Cinzentos Empregando um Sistema Fotovoltaico Conectado à Rede Elétrica Trifásica

Este trabalho apresenta um sistema fotovoltaico (FV) trifásico de duplo estágio de conversão de energia conectado à rede elétrica, o qual é capaz de lidar com problemas de sombreamentos parciais em arranjos FV. Condições de sombreamentos parciais podem afetar o desempenho de sistemas FV, uma vez que as técnicas tradicionais de seguimento do ponto de máxima potência (MPPT – Maximum Power Point Tracking) podem operar em pontos de máximos locais de potência ao invés de máximos globais. Sendo assim, são apresentas quatro técnicas de MPPT bioinspiradas no método de otimização dos lobos cinzentos (GWO - Grey Wolf Optimization), as quais são capazes de extrair o ponto de máximo global de potência do sistema. Tais técnicas são denominadas neste trabalho como GWO, GWO-Beta, GWO-IC (Incremental Conductance) e GWO-P&O (Perturb and Observe). As referidas técnicas são avaliadas e comparadas uma com as outras empregando um sistema FV composto por um conversor CC/CC Boost e um inversor trifásico a três braços. Por meio de resultados de simulação e experimentais o desempenho e eficácia das quatro técnicas de MPPT são avaliadas levando em consideração o tempo de convergência, as oscilações de potência em regime permanente, assim como a eficiência na busca do ponto de máxima potência.

The Performance Analysis of a Three-Phase Grid-Tied Photovoltaic System in a Tropical Area

The Performance Analysis of a Three-Phase Grid-Tied Photovoltaic System in a Tropical Area