Estimation of Grid Frequency for a Photovoltaic System

Abstract

The dissertation presents a synchronization technique meant to provide an estimation of grid frequency0and positive sequence component of three phase distorted grid voltages. Although the Phase Locked Loop (PLL) has been broadly used as an execution technique, it requires an effort when the grid voltages are severely distorted by harmonics and unbalances. Thus the performance of the PLL can be further improved by using an observer with the existent PLL. The positive sequence voltage from the distorted grid voltage is estimated with the help of observer and PLL. Thus in this thesis an observer based PLL method is used for frequency estimation. Since the observer based PLL technique is immune to noise and distortions which are present in power system signals, it is used for distributed generation units, ex: solar power generation systems that use power electronics converters as their integral part. Under the polluted grid conditions, the performance of observer based PLL method have been performed by in MATLAB/SIMULINK. And also a hardware prototype MATLAB interfaced XILINX SYSTEM GENERATOR have been performed to prove the effectiveness of the proposed technique. The results so obtained from Software (MATLAB) Simulation and hardware (XILINX) simulation have been compared and the performance of the proposed method have been discussed.