Digital Image Tampering – A Threat to Security Management

Abstract: This paper presents analysis and improvement of power quality (voltage sag, swell and harmonics) performance of smart grid connected inverter used in distributed generation .The structure of the designed controller consists of outer power with harmonic control loop ,middle voltage control loop and inner current control power loop for real and reactive power control in dq reference frame .The developed controller controls the real and reactive power supplied by the DG(Distributed Generation) at the PCC(Power Controlled Converter). The controller is designed to deliver current at unity power factor at PCC. An increase in reactive power demand and harmonics at PCC due to change of load and grid impedance variation, would affect the system voltage at PCC. Renewable energy resources (RES) are being increasingly connected in distribution systems utilizing power electronic converters. This report presents a novel control strategy for achieving maximum benefits from these grid-interfacing inverters when installed in 3-phase 4-wire distribution systems. The inverter is controlled to perform as a multi-function device by incorporating active power filter functionality. The inverter can thus be utilized as: 1) Power converter to inject power generated from RES to the grid, and 2) Shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current.
All of these functions may be accomplished either individually or simultaneously. With such a control, the combination of grid-interfacing inverter and the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appears as balanced linear load to the grid. This new control concept is demonstrated with extensive MATLAB/Simulink simulation studies and validated through digital signal processor-based. The comparisons have been made with the conventional SYPWM based PI controller employed for the same hybrid scheme with the proposed controller .The results clearly bring out suppleness of the proposed scheme.

Keywords: Power Quality, Renewable energy resources (RES), Proportional Integral Control, MATLAB/Simulink .