Social, economic, and ecological influences later led to new arrangements where a utility company might enter into long-term power purchase or sale agreements with neighboring utility companies, or locate new generation facilities outside of their system and enter into long-term agreements for transmission rights to deliver that energy to their own system.
As utility companies began integrating their operations in more complex ways with their neighbors, they evolved into a vertical organizational structure with three tiers: Generation, Transmission, and Scheduling.
As load demands increase or new generation assets come online in their systems, they upgrade existing facilities or construct new transmission corridors to maintain the reliable delivery of energy.
The Energy Policy Act of 1992 (EPAct) laid the initial foundation for the eventual deregulation of the North American electricity market.
This Act called for utility companies to allow external entities fair access to the electric transmission systems in North America.
Recognizing competition was coming, electric utility companies began modifying their scheduling functions by forming affiliated Power Marketing departments.
With open access, anyone with the proper resources and/or creditworthiness could purchase the rights to generation, move it across the transmission network (provided adequate capacity was available), and deliver it to a place of higher demand.
Affiliated power marketers could no longer work alongside the transmission operators who were charged with treating them and external parties equally, and at the same time affiliated power marketers would no longer have any "inside information" on the availability of the transmission system nor the transactions being scheduled on it.
Order 889 went to great lengths to detail exactly how all participants in the electricity market should interact with transmission providers.
Transmission operators perform system studies in various future time frames to determine how much transfer capacity is required to serve their own "native load", and how much capacity must remain as a buffer to prevent unscheduled or accidental overflows that can damage high voltage equipment.
The difference between the capacity needed to serve load and to maintain safe flow margins can be made available for purchase on the OASIS node.
In 2012 the North American Energy Standards Board (NAESB), an industry council, assumed responsibility [4] for TSIN.