How tie lines interconnect the grid

EnergyLines November/December 2018


Hoosier Energy has interconnect points with other utilities on the grid. As power is transmitted – either being purchased or sold from one utility to another – equipment known as tie lines are used to provide an economical path for the energy to be supplied to the load.



Most of us take for granted the miles and miles of transmission lines that interconnect to keep energy flowing 24/7. For Hoosier Energy, one critical component for serving member co-ops is ensuring the strength and resiliency of its transmission tie lines (also called interconnection points). Transmission tie lines connect Hoosier Energy’s part of the grid to other systems, allowing energy to flow both in and out of the Hoosier Energy power network.


Tie lines are like two-way streets. They allow Hoosier Energy to provide energy to maximize output, reducing the need to buy from other energy companies, and import energy onto our part of the grid. Conversely, they serve as a gateway to sell energy outside the network or bring energy generated by Hoosier Energy to our load regardless of the transmission ownership.


The ability to transfer energy allows for faster restoration and reduced outage minutes to member co-ops.


Tie lines also provide voltage and frequency support during emergencies.


“Keeping our tie lines in working order keeps our system strong,” says Chris Ware, Manager of Power Delivery Engineering. If the primary source is not available, he says, we also have emergency tie lines that can be used for restoration.


Hoosier Energy has tie lines with Duke, Indianapolis Power & Light, Vectren, Big Rivers and Ameren to ensure safe and reliable service to members.


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