Distributed Power

Tests on Cable Constructions. The Association of Edison Illumination Companies (AEIC) has approved an accelerated cable hfe test in which typical underground distribution power cables can be statistically compared based on their resistance to water treeing (number of days to fail). The comparison can be made by varying the type of insulation and/or other cable layers in an environment that contains hot water (90°C) under 8V/fi (200 V/mil) voltage stresses (four times the typical power cables operating voltages). 

These are comparatively smaller assemblies and distribute power to the utilities of an installation, which can be an industrial, a commercial or a residential complex. The utilities may be one or more of the following essential services ... 

This is the most common scheme in normal use for any power system with more than one feeder, connected to a common bus, such as for distribution and sub-distribution power networks, having a number of load points, controlled through a main incoming feeder. In a switchgear assembly, for instance, common protection may be provided at the incoming for a ground fault or combined 0/C and G/F protections as discussed above. In such cases, a restricted G/F protection may not be appropriate or required, as the protection now needed is sy.stem protection, rather than individual equipment proteelion. The incomer must operate whenever a fault occurs at any point on the system. Moreover, for an LT system, where it may not be desirable or possible to provide individual protection to each feeder, such a scheme is adopted extensively. 

Distributed Power Editorial, Distributed Generation Understanding The Economics , May-June, 2000. 

The organization of the power system within the final product should complement the product philosophy. The goal of the power system is to distribute power effectively to each section of the entire product and to do it in a... 

For those produets that have many diverse modules that ean be reeonfigured over the life of the produet, sueh as PCB eard eage systems and eellular telephone ground stations, ete., then the distributed power system is more appropriate. This type of system typieally has one main bulk power supply that provides power to a bus whieh is distributed throughout the entire produet. The power needs of any one module within the system are provided by smaller, board-level regulators. Flere, voltage drops experieneed aeross eonneetors and wiring within the system do not bother the eireuits. 

The nontransformer isolated topologies are used for board-level converters. These are in distributed power systems where an intermediate bus voltage is distributed throughout the system and each board within the system has its own power supplies. The bus voltage is always a safe level that is not deemed lethal to the operator of the equipment, therefore dielectric isolation is optional. I still heartily recommend transformer isolation in most applications. The added cost... 

The DC filter choke is used for ripple voltage and current reduction on the output of the switching power supply immediately following the existing filters. It is also used as an EMI filter on switching power supplies that have a single power line on the input, such as battery and distributed power systems. 

This switehing power supply is intended as a bulk power supply within a distributed power system. It will provide a safe bus voltage of 28 volts de to the system. It has an ae input in whieh a tap must be ehanged in order to aeeommodate either a 110 VAC or a 240 VAC ae input power system. Please refer to Figure 3-77. 

Rail-transported coal is typically moved in unit trains that operate in dedicated shuttle seivice between a mine and a destination. Unit trains operating in the western United States and Canada consist of 100 to 120 lightweight aluminum railcars cainying upward of 121 tons (110 tonnes) of coal apiece, or more than 14,000 tons (12,700 tonnes) per train. In the 1990s, distributed power (DP) came into widespread use in the western United States. In this system a remotely controlled engine is put into the middle of a train, allowing greater traction and control of train motion. DP trains can consist of 135 cars and are the most efficient method of rail transportation of coal. 

Proton Exchange Membrane 0-85 Can operate at ambient temperature High power density Sensitive to CO-poisoning Need for humidification Transportation Distributed Power... 

Phosphoric Acid 170-220 Mature Relormate-intolerant Bulky Cannot start from ambient Heavy-duty transportation Distributed Power... 

Molten Carbonate -650 Some fuel flexibility High-grade waste heat Fragile electrolyte matrix Electrode sintering Distribute power Utilities... 

Solid Oxide 800-1000 Maximum fuel flexibility Highest co-generertion efficiency Exotic materials Sealing and cracking issues Distribute power Utilities... 

There also are circumstances where income tax provisions reduce the after-tax rate of return on such investments below those available in other sectors. For example, certain types of electricity-generating property (such as those used in distributed power applications) may have useful lives that are substantially shorter than the tax lives permitted for cost recovery. In such instances, the after-tax rate of return will be negatively affected by these specific provisions. 

The monitoring uncertainty and operational transient margin is to ensure that the minimum DNB ratio is calculated at the worst operating condition. The assumed worst operating condition consists of a power surge of 12% in a worst power distribution (power skew at top), accompanied by an inlet coolant temperature elevation of 4°F (2°C) and a pressure swing of 30 psi (0.2 MPa). A set of worst hot channel factors in core life should also be used in evaluation of the worst power distribution. Such an assumed worst operating condition is obviously overly... 

Increasing the utilization of hydrogen as an energy carrier in transportation and distributed power generation applications based on proton exchange membrane (PEM) fuel cells will create a demand for plants that produce high-purity hydrogen as the primary product. 

For smaller scale, multi-MW distributed power systems a market could potentially open in the shorter term opportunities for plants under 1 MW are only seen for SOFCs but are hard to envision for MCFCs due to their inherent complexity. 

LARGE-SCALE DISTRIBUTED POWER, INDUSTRIAL COGENERATION, AND CENTRAL GENERATION... 

Use of H2-based fuel cells for generating electricity on a small scale close to areas where the electricity is needed would enable distributed power generation and ease the burden on the current electric grid. 

A hydrogen economy may be jump started with distributed power. These are stationary fuel cells that generate on-site power in critical ar-... 

In addition to high-profile fuel cell applications such as automotive propulsion and distributed power generation, the use of fuel cells as auxiliary power units (APUs) for vehicles has received considerable attention (see Figure 1-9). APU applications may be an attractive market because it offers a true mass-market opportunity that does not require the challenging performance and low cost required for propulsion systems for vehicles. In this section, a discussion of the technical performance requirements for such fuel cell APUs, as well as the current status of the technology and the implications for fuel cell system configuration and cost is given. 

Active technology development efforts in both PEFC and planar SOFC technology, driven primarily by the interest in distributed generation and automotive propulsion markets, have achieved significant progress in the development of these technologies. For distributed power applications refined and even early commercial prototypes are being constructed. 

It is estimated that the fuel cell market for distributed power and demonstration projects and contracts amounted to about 100 million for 2003. Research and development contracts to develop fuel cells for automotive propulsion and stationary energy storage are an order of magnitude larger. 

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