Improving Dynamic Stability of Microgrids with More Inverted Scattered Sources in the Presence of Active Loads

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Improving Dynamic Stability of Microgrids with More Inverted Scattered Sources in the Presence of Active Loads

ارائه دهنده: Provider: Farhad Abdolmaleki

اساتید راهنما: Supervisors: Dr. Mohammad Amin Ghasemi , Dr. Hamid Reza Karami

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr. Mohammad Mehdi Shahbazi-Dr. Majid Ghani Zarch

زمان و تاریخ ارائه: Time and date of presentation: 2022-01-31 at 16:00

مکان ارائه: Place of presentation: Engineering College

چکیده: Abstract: Microgrids are gaining increasing attention as a platform for maximum use of distributed generation resources, active and controllable loads, and energy storage. One of the major concerns about the reliable operation of a microgrid is the stability and, most importantly, the small-signal stability. The main issue in the stability analysis of a Microgrid is its modeling. In fact, extracting a comprehensive and accurate model, considering all the components and their interactions is necessary for the stability analysis and designing a coordinated and efficient controller for the system. For this purpose, small-signal modeling of all effective elements is required. Loads are one of the most effective elements in microgrid stability, and accurate modeling of loads can lead to accurate results. Although different loads can be present in the microgrid, the available research documents consider the microgrid with passive loads (impedance); While a significant part of microgrid, loads can be active loads such as drives, rectifiers, etc. Another important factor that plays a key role in microgrid stability is the controllers used by microgrid inverter sources and active loads, and the design of appropriate controls can have a significant impact on microgrid stability. In this thesis, various elements of an AC microgrid are analyzed and their state-space models are extracted in the d-q frame. By combining the extracted models and coordinating all models in the same d-q frame, the state-space model of an islanded studied microgrid is extracted. Then, using the root locus method, the stability of the system in the presence and absence of active load is investigated; results show that the presence of active loads in the microgrid can reduce its stability margin. Accordingly, in order to improve the stability of the studied system, the current loop controller of the active load is modified and an internal model-based controller (IMC) is designed for it. By applying the internal mode controller, the state-space model of the system is updated and the system stability is re-analyzed and compared with the system stability when the conventional controller is used. The results show the internal mode control improves the eigenvalue pattern and the stability of the system. To validate the results of the stability analysis using the root locus method, several dynamic simulations in MATLAB / SIMULINK have also been performed

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