A Greener Grid
• Distributed Energy Resources
• Power Quality/Energy Sensing
• Demand Side Management/Direct Load Control
The U.S. electrical generation and distribution follows a model established during the industrial revolution, which continued unchallenged until the 1970’s energy crisis. This model capitalized on the combination of economies of scale and cheap fuel, and resulted in the construction of large capacity generation plants located close to fuel sources and away from populated areas. Generation was connected to load centers via High Voltage (HV) Transmission lines and Medium and Low Voltage (MV and LV) Distribution lines.
In 1996, the Federal Energy Regulatory Commission (FERC) issued Order 888, eliminating discriminatory access to transmission lines by implementing a universally applied transmission tariff ensuring the recovery of stranded costs utilities might accrue in the transition to a competitive market. Before Order 888, long haul energy shipments were reserved for emergencies serving as a backup against sudden loss of power. This limited use of long haul transmission lines aided system reliability.
With deregulation, electricity generated at a lower cost away from a load center can be “shipped” over the long haul HV transmission lines to the load center at a lower cost than using electricity produced locally. This situation results in utilities capitalizing on the cheaper electricity from more distant sources thus using up the capacity of the long haul transmission lines, effectively removes their grid supporting capacity which results in more vulnerable national distribution grid.
In light of the system wide vulnerability highlighted by the 2003 Northeast Blackout, many utilities are looking into Distributed Energy Resources (DER) to increase system reliability and incorporate emerging renewable energy resources.
DER includes the subcategories of distributed generation and micro generation and is the idea of smaller scale generation and energy resources distributed throughout load centers, moving away from the early large scale generation models. DER can include small scale fossil fuel generation such as natural gas turbines or renewables like roof top solar, wind turbines, as well as battery and flywheel power reserves.
Combining DER elements into the distribution grid will require intelligent integration and management of these devices with the larger distribution grid through a real-time two-way communications network between the utility’s network operation center (NOC) and the DER elements to optimize their usage. When part of a combined intelligent system, DER can meet local demand, relieve grid congestion, address most power quality issues and mitigate local wholesale prices.
DER elements can function as capacity deferral, congestion relief or voltage support. Modern grid DER technologies have been utilized to prevent grid shut downs by diverting power from the power surges as these systems can include smart control of the grid’s thyristors (large scale transistors) and giant capacitors to divert power from troubling congestion to underutilized grid lines. Further, the insertion of superconducting fault current limiters to the transmission line coupled with DER and smart communications can prevent unexpected, rapid surges in current to beyond the pre-set safe limits of the line.1.
1. Smart Electric Grid of the Future: A National “Distributed Generation” Test Bed p2