Page 368 - Renewable Energy Devices and System with Simulations in MATLAB and ANSYS

14 Microgrid for High-Surety

Power: Architectures, Controls,

Protection, and Demonstration

Mark Dehong Xu, Haijin Li, and Keyan Shi

CONTENTS
Abstract ..........................................................................................................................................355
14.1 Highly Reliable Microgrid ....................................................................................................356
14.2 Architectures .........................................................................................................................356
14.2.1 Star Architectures ......................................................................................................356
14.2.2 Multiple-Star Architecture ........................................................................................358
14.2.3 Ring Architecture ......................................................................................................359
14.2.4 Hybrid Architecture ..................................................................................................359
14.2.5 Evaluation of Architectures ......................................................................................360
14.3 Control ..................................................................................................................................365
14.3.1 Operation Modes of Super UPS ...............................................................................365
14.3.1.1 Grid Normal Mode .....................................................................................365
14.3.1.2 Gas Engine Power Mode............................................................................367
14.3.1.3 Battery Power Mode ..................................................................................367
14.3.1.4 Fuel Cell Power Mode ...............................................................................367
14.3.1.5 Bypass Mode ..............................................................................................369
14.3.2 Power Management of Multiple Sources in Super UPS ...........................................369
14.3.2.1 Fuel Cell Unit Power Management ............................................................372
14.3.2.2 Gas Engine Unit Power Management ........................................................374
14.4 Protection ..............................................................................................................................376
14.4.1 Short-Circuit Fault Current Analysis ........................................................................376
14.4.2 Solid-State DC Circuit Breaker ................................................................................380
14.5 Demonstration .......................................................................................................................382
14.5.1 Super UPS Platform ..................................................................................................382
14.5.2 Experimental Results ................................................................................................385
14.6 Summary ...............................................................................................................................390
Acknowledgment ...........................................................................................................................390
References ......................................................................................................................................390

ABSTRACT
Microgrid is an emerging and promising field because of the ever-increasing installation of renew-
able energy and concerns to the environment [1–4]. Microgrid usually comprises energy sources,
storage components, and local loads. It can be connected to the outer grid or operates independently.
The energy sources include renewable energy sources, such as wind power, photovoltaic power,
and fuel cells, as well as traditional power sources such as diesel generation and gas turbine. Since

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