UGA Health Science Campus Microgrid StudyCapstone Team #14: Jack McElhannon, Alex Ponts, Kenneth Thomas, Blake Salter, Mayah Booker

Faculty Advisor: Dr. Jin Ye

Background Simulink Model Protection and Control

Sponsor/Client:

Microgrid systems allow for an independence from the standard grid electricity. Instead of relying on utility scale generation from a large power producing plant, electricity is generated by on-site, distributed generation. This increases the resiliency of the both the Health Science Campus and Georgia Power’s existing grid. This system allows multiple potential power sources for the campus. This independence also will relieve the grid of the campus load burden and allow for the optimization of energy production. The goal of this project was to design and evaluate the implementation of a microgrid system on the UGA Health Science Campus.

Design Requirements

The overall goal of this design is to give Georgia Power and the University of Georgia the information necessary to pursue similar projects in the future. The proposed microgrid system must service a 500 kW base load with 10 additional EV charging stations. The system must also include solar generation, battery storage, and a natural gas microturbine. It is required to operate at a 95% independence of the main grid at maintain electrical inertie at 12kV. The system design consists of a Matlab Simulink Model for power characteristics, a single-line diagram for protection and controls, and a cost analysis of the system. This analysis will provide Georgia Power insight into grid resilience, renewable energy technology, and integration of smart energy management systems.

With the help of the Intelligent Power Electronics and Electric Machine Laboratory, we developed a model of our proposed system in Matlab Simulink. The Simulink design incorporates generation, distribution, and load components, allowing us to study the power characteristics of the proposed system. While the design is not representative of the actual system components which would be implemented in physical construction, it is invaluable in testing power stability, various switching states, and measuring voltage, current, and power outputs throughout the system.

The Simulink design incorporated an array of subsystems representing our various generation, distribution, and load components. The three main subsystems included within the design were the PV Array subsystem (displayed above), the Battery subsystem, and the Load subsystems. Each subsystem incorporates datasheet specifications from the chosen respective components for each subsystem:

● PV: Sunpower SPR-X21-470-COM● Battery: LG Chem R1000 M48218P5B● Load: Load data and transformer specs from pre-

existing components● Natural Gas Turbine: Capstone C600s CNG

Model Subsystems

The team developed a protection and control scheme in order to protect our system from potential faults. This scheme is based off the power flow results of our Simulink model. We anticipated our expected values of powerflow and monitored them using CT’s placed in strategic locations. These CT’s send current flow data to microprocessors, which then communicate with the breakers and switches to control switching states. Using this scheme, The team has established seven different zones of protection that look at:

● Overcurrent protection of battery inputs● Overcurrent protection of the 480 V and 12 kV busses● Reclosing options for fault clearing● Differential current protection of the step-up transformer

System ThreatsThe team researched the weather patterns of Athens, Ga

to determine physical threats to our system. The biggest threat to our system will be storm damage. High winds, heavy rain, hail, and high temperatures are all threats that could damage our assets or cause a fault in the system.Using this data, the team acknowledged times when risks to the system are highest .