Engineering Commons^™

Stability Analysis Of Microgrids Using Markov Jump Linear Systems, Gilles Mpembele

Doctoral Dissertations

"This research discusses stochastic models for a microgrid operating between standalone and grid-tied modes. The transitions between different modes are modeled as a continuous-time Markov chain (CTMC). In each operating mode, the system is modeled using conventional differential algebraic equations (DAEs), linearized around some equilibrium point.

In Topic-I, a model is developed using the Stochastic Hybrid Systems (SHSs) formulation. The microgrid is modeled as a Markov jump linear system (MJLS), which is a type of SHS in which the discrete events evolve according to a Continuous Time Markov Chain (CTMC). The model allows for the derivation of Ordinary Differential Equations …

Three-Phase Power Converter Based Real-Time Synchronous Generator Emulation, Liu Yang

Doctoral Dissertations

To bridge the gap between power system research and their real application in power grids, a Hardware Test-Bed (HTB) with modular three-phase power converters has been developed at the CURENT center, the University of Tennessee, Knoxville, to emulate transmission level power systems with actual power flowing.

This dissertation focuses on the development and verification of a real-time synchronous generator (SG) emulator in the HTB. The research involved in this dissertation aims at designing a proper control to achieve emulator performance goal and investigating the sources of error and its influence on interconnected SG-emulator networks.

First, different interface algorithms (IAs) are …

Gain Tuning Of Proportional Integral Controller Based On Multiobjective Optimization And Controller Hardware-In-Loop Microgrid Setup, Kumaraguru Prabakar

Doctoral Dissertations

Proportional integral (PI) control is a commonly used industrial controller framework. This PI controller needs to be tuned to obtain desired response from the process under control. Tuning methods available in literature by and large need sophisticated mathematical modelling, and simplifications in the plant model to perform gain tuning. The process of obtaining approximate plant model conceivably become time consuming and produce less accurate results. This is due to the simplifications desired by the power system applications especially when power electronics based inverters are used in it. Optimal gain selection for PI controllers becomes crucial for microgrid application. Because of …

Small Signal Modeling And Analysis Of Microgrid Systems, Md. Rasheduzzaman

Doctoral Dissertations

This dissertation focuses on small-signal modeling and analysis of inverter based microgrid systems. The proposed microgrid consists of two microsources placed on two different buses. The buses are connected using a distribution feeder with some impedance. The proposed microgrid can operate with the grid support, or without the grid support. When operated without the grid support, the standalone system’s microsources participate in controlling the system voltage and frequency. For a non-inertia source, such as the inverter, the load perturbations play an important role in system dynamics. In paper-I, such complex system was studied.

In the grid-tied mode, the microsources share …

Optimization In Microgrid Design And Energy Management, Tu Anh Nguyen

Doctoral Dissertations

"The dissertation is composed of three papers, which cover microgrid systems performance characterization, optimal sizing for energy storage system and stochastic optimization of microgrid operation. In the first paper, a complete Photovoltaic-Vanadium Redox Battery (VRB) microgrid is characterized holistically. The analysis is based on a prototype system installation deployed at Fort Leonard Wood, Missouri, USA. In the second paper, the optimal sizing of power and energy ratings for a VRB system in isolated and grid-connected microgrids is proposed. An analytical method is developed to solve the problem based on a per-day cost model in which the operating cost is obtained …

Modeling And Optimization Of Energy Storage System For Microgrid, Xin Qiu

Doctoral Dissertations

"The vanadium redox flow battery (VRB) is well suited for the applications of microgrid and renewable energy. This thesis will have a practical analysis of the battery itself and its application in microgrid systems. The first paper analyzes the VRB use in a microgrid system.

The first part of the paper develops a reduced order circuit model of the VRB and analyzes its experimental performance efficiency during deployment. The statistical methods and neural network approximation are used to estimate the system parameters. The second part of the paper addresses the implementation issues of the VRB application in a photovoltaic-based microgrid …