306 research outputs found
Modulation and Control Techniques for Performance Improvement of Micro Grid Tie Inverters
The concept of microgrids is a new building block of smart grid that acts as a single controllable entity which allows reliable interconnection of distributed energy resources and loads and provides alternative way of their integration into power system. Due to its specifics, microgrids require different control strategies and dynamics of regulation as compared to ones used in conventional utility grids. All types of power converters used in microgrid share commonalities which potentially affect high frequency modes of microgrid in same manner. There are numerous unique design requirements imposed on microgrid tie inverters, which are dictated by the nature of the microgrid system and bring major challenges that are reviewed and further analyzed in this work. This work introduces, performs a detailed study on, and implements nonconventional control and modulation techniques leading to performance improvement of microgrid tie inverters in respect to aforementioned challenges
Advanced Control and Stability Enhancement of Grid-Connected Voltage-Source Inverter with LCL-Filter
Resonance Damping of LCL Filters Using Capacitor-Current Proportional-Integral Positive Feedback Method for Grid-Integrated Fuel Cell System
Nowadays, the use of grid-integrated inverter proton exchange membrane fuel cell (PEMFC) systems is becoming more prevalent due to their efficiency and favorable environmental effects. Switching the grid-connected inverters causes high-frequency harmonics, which are eliminated using LCL filters. These filters are susceptible to instability when their resonant frequency is affected by changes in network impedance. Active damping methods are used to weaken the resonance of LCL filters. However, the grid-connected inverter is prone to be unstable under grid impedance variations due to the negative equivalent resistance resulting by digital control delays. As a solution to this problem, the capacitor-current proportional-integral (PI) positive feedback active damping approach is suggested in this study. It can provide a positive equivalent resistance almost within the Nyquist frequency, i.e., the entire controllable frequency range. As a result of the proposed method, the grid-connected inverter achieves strong stability against grid impedance variations. In this study, a PEMFC stack is used to produce and inject power into the weak grid using the proposed controller. MATLAB/Simulink simulation results are presented to verify the validity of the proposed method. The simulation results show that the proposed method is stable against changes in grid impedance and PEMFC parameters, and provides a good performance
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