One of the most important developments of the energy age may be the solid-state transformer for power distribution.
This device will act as a ‘power supply’ for a building. It will deliver the voltages and frequency needed by different systems in the building in the same way that a computer power supply provides several different configurations of power to a computer motherboard.
A typical transformer is an induction device whereby electricity is transferred from one winding to another and increased or decreased based on the relationship of the windings. An Intelligent Universal Transformer (IUT) is a solid-state device, a power supply, that can intelligently provide optimal power to loads.
Transformers are essential elements of the power grid; they convert the high-voltage electricity delivered by power lines to the 120-volt supply needed for consumers. Typically, one transformer supplies power to several homes. They come in three varieties: pole-mounted canisters; ground-level metal boxes; and, rarely, underground transformers. See also: Transformers.
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pole-mounted canisters
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ground-level metal boxes
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underground transformers
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Problems with these transformers include:
Power Quality. Equipment in one building may inject a signal into the powerlines, which pass through a transformer and could affect equipment in another building.
Efficiency: Transformers consume some of their power, and their collective impact on the grid is significant.
Limitations: Transformers cannot change the frequency of the electricity passing through them and cannot use direct current.
Static: Once a transformer is set, changes need to be manually made by switching on changing the wiring.
Ecology: Power Transformers contain mineral oils, a source of pollution.
The solid-state power transformer mitigates all power quality problems, converts all loads to sinusoidal and unity power factor, thereby increasing the efficiency of the entire distribution grid, completely mitigates secondary faults, readily supplies dc offset loads, and features shallow no-load losses. In addition, the design does not utilize mineral oil. It is thus environmentally friendly and, simultaneously, based upon a technology (power electronics) in which component costs are falling sharply.
Benefits of the solid-state universal intelligent transformer:
Energy Efficiency: The existing transmission systems can be better optimized. More power can be delivered through the same wires.
Flexibility: The Intelligent Universal Transformer will reliably deliver diverse power, such as 400 Hz service, D.C. service (for hybrid electrical systems), and three-phase control from a single-phase line.
Power Quality: Sag correction and harmonic filtering can be built into the intelligent universal transformer.
Configurable: Because one device can be used in many configurations, inventory and spare parts can be reduced. Maintenance costs are reduced.
Environmental Concerns: The Intelligent Universal Transformers will contain no hazardous liquid dielectrics like conventional transformers. The hazards and costs of spills and cleanups will be avoided.
The Energy Systems Analysis Consortium (ESAC) comprises Purdue University, the University of Missouri-Rolla, the University of Wisconsin-Milwaukee, the U.S. Naval Academy, the U.S. Navy Postgraduate School, and the University of Illinois Urbana-Champaign has been developing this and already holds one patent. EPRI, holding another patent, has published several papers on the project.
Patents:
Deep diode solid state transformer 4024565: General Electric, 1977
An array of columnar structures are provided in a body of semiconductor material. The material of each columnar structure is recrystallized material of the body having solid solubility of dopant metal therein. Means are provided for connecting the columnar structures into two series electrical circuit arrangements to function respectively as the primary and secondary windings of a deep diode solid state transformer.
Multilevel converter-based intelligent universal transformer, EPRI, 7,050,311, 2006
A multilevel converter-based, intelligent, universal transformer includes back-to-back, interconnected, multilevel converters coupled to a switched inverter circuit via a high-frequency transformer. The input of the universal transformer can be connected to a high-voltage distribution system, and the output of the universal transformer can be coupled to low-voltage applications. The universal transformer is more minor than conventional copper-and-iron-based transformers yet provides enhanced power quality performance and increased functionality.
See also: EPRI
Design Challenges:
A solid-state transformer would be semiconductor-based, and no current semiconductor material configurations can handle the 10kV distribution grid voltages.
Please get in touch with Mark C. Robinson with comments and updates.
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