A new SOGI-PLL method based on fuzzy logic for grid connected PV inverter

Phase angle detection of the grid voltage is an imperative part of control in most applications, especially for the synchronization of the current injected by the grid-connected photovoltaic inverters. Consequently, fast and accurate detection of the phase angle, frequency and amplitude of the grid voltage are indispensable data to ensure a correct generation of reference signals and operation of the grid connected inverters. We present in this work a new phase-locked loop (PLL) method for single-phase systems. The novelty is to generate an orthogonal voltage system using a second-order generalized integrator (SOGI), followed by a Park transformation, whose quadrature component is forced to zero by the fuzzy logic, in order to obtain rapid detection and a more accurate picture of the phase angle. Furthermore, simulation results with PSIM software will be submitted to verify the performance and effectiveness of the proposed method strategy. Finally, the experimental test will be used to extract the result and discuss the validity of the proposed algorithm.

DSOGI-PLL based power control method to mitigate control errors under disturbances of grid connected hybrid renewable power systems

The control of power converter devices is one of the main research lines in interfaced renewable energy sources, such as solar cells and wind turbines. Therefore, suitable control algorithms should be designed in order to regulate power or current properly and attain a good power quality for some disturbances, such as voltage sag/swell, voltage unbalances and fluctuations, long interruptions, and harmonics. Various synchronisation techniques based control strategies are implemented for the hybrid power system applications under unbalanced conditions in literature studies. In this paper, synchronisation algorithms based Proportional-Resonant (PR) power/current controller is applied to the hybrid power system (solar cell + wind turbine + grid), and Dual Second Order Generalized Integrator-Phase Locked Loop (DSOGI-PLL) based PR controller in stationary reference frame provides a solution to overcome these problems. The influence of various cases, such as unbalance, and harmonic conditions, is examined, analysed and compared to the PR controllers based on DSOGI-PLL and SRF-PLL. The results verify the effectiveness and correctness of the proposed DSOGI-PLL based power control method

STEROWANIE ORAZ SYNCHRONIZACJA DWUPOZIOMOWEGO FALOWNIKA NAPIĘCIA W WARUNKACH PRZEJŚCIOWEJ ASYMETRII NAPIĘĆ SIECI

This paper presents the operation of grid tied, two level voltage source inverter (VSI) during network voltage unbalance. The control system was implemented in synchronous rotating reference frame dq0 (SRF). Two types of control structures were investigated herein. First utilizes the Double Decoupled SRF Phase-locked loop (DDSRF-PLL) synchronisation with positive and negative sequence currents control. Second one is simplified system that does not provide symmetrical components decomposition and decoupling for synchronisation. Simulation results exhibited a superior performance of the DDSRF-PLL control system under grid voltage unbalance.Niniejszy artykuł przedstawia pracę dwupoziomowego falownika napięcia współpracującego z siecią, podczas przejściowej asymetrii napięć. System sterowania został zaimplementowany w wirującym układzie synchronicznym dq0. Przeanalizowano dwa typy sterowania. W pierwszym zastosowano metodę synchronizacji z odprzęganiem DDSRF-PLL wraz z możliwością kontroli prądów składowej zgodnej i przeciwnej. Drugi natomiast w swoje uproszczeni formie nie pozwalała na sterowanie obu składowych symetrycznych, zabrakło również odprzęgania podczas synchronizacji z siecią. Wyniki symulacji pokazały o wiele lepsze działanie pierwszej metody sterowania