Research Highlights
A Smart and Flexible Microgrid with a Low-cost Scalable Open-source Controller
By Dr . Fred Wang , Dr . Yilu Liu , Dr . Leon Tolbert , Dr . Lin Zhu and Yiwei Ma ( PhD student )
Microgrids ( MGs ), with their distributed energy resources ( DER ) and ability to operate both in grid-connected and islanded modes , can significantly improve reliability and resilience of the power grid . For example , when a natural disaster , such as Hurricane Sandy , caused millions of customers to be without electricity for weeks and billions of dollars of economic losses , MGs could have made an appreciable difference . A MG controller is essential to achieving smooth transition between the grid-connected and islanded operation modes , and also for optimal operation during both modes .
While there have been dozens of MG systems developed around the nation since the concept was proposed a decade ago , almost all of them were deployed for serving special sites such as military bases , or university / business campuses . MGs have not yet been commercially utilized for communities in the U . S due partly to the high cost of added energy resources such as battery energy storage systems , and also due to the high deployment cost of sensors , communication infrastructure , and proprietary controllers .
ARPA-E is funding CURENT UTK team to develop and demonstrate a community-based smart and flexible MG with an open source scalable MG controller for enhanced functionality and low cost . One end project objective is to have the controller developed , tested and ready for commercialization . Based on the smart distribution system of the CURENT member Electric Power Board of Chattanooga ( EPB ), the MG and its controller will make use of the existing intelligent switches and fiber optics links for control and communications . Minimum number of new switches , sensors or communication links will be needed . In addition , flexible grid interface points will be featured in this project for better asset use , reliability , and economics , as shown in Figure 1 . In addition to EPB , other industry partners on the project include CURENT industry members National Instruments ( NI ), Electric Power Research Institute ( EPRI ), and TVA . The Green Energy Corp ( GEC ) will work as the commercialization partner .
Figure 1 : Conceptual MG diagram with multiple utility feeds ( PCC : Point of Common Coupling )
As shown in Figure 2 , three main technical tasks are being performed : MG design , MG controller development , and system testing . The MG control algorithms will be implemented on NI general-purpose controllers to further reduce the deployment cost , and the system will be developed and tested in multi-platform environment including CURENT ’ s unique grid emulation platform Hardware Testbed ( HTB ).
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CURENT Newsletter Spring 2017