Showing papers on "Stand-alone power system published in 1987"

The UoSAT-2 spacecraft power system

Abstract: Four panels of Si solar cells provide power to charge packs of NiCd battery cells via a battery charge regulator. Regulated + 10 V, − 10 V and + 5 V supplies from a centralized power regulating system, as well as + 14 V unregulated battery voltage, are supplied to a power distribution module which uses bipolar transistors to switch power as required to different loads. As UoSAT is in eclipse for over one-third of its orbit, batteries with good cyclic performance must be provided. UoSAT-2 operates on a negative power budget where the power required to keep all systems fully operational is greater than the solar power available. Consequently, significant groundstation effort is required to monitor and manage the power system. Future satellites may incorporate a microprocessor-driven control element in a further step towards system autonomy.

Gas heating/fuel cell/electrical heat supply "Multi-Mini Combined Heat and Power System"

Abstract: Fuel cells are connected ahead of the gas heating furnaces of residential areas; the electricity from them in conformity with demand simultaneously serves to supply heat in other areas, mostly substituting for oil there. In conjunction with electric heat pumps, system utilisation rates of up to 180% can be achieved. Each additional residence supplied increases the gas demand by only 30% of a residence demand. The obstacle to the utilisation of such energy-saving combined systems constituted by high costs is avoided in this method by multiple use of existing utility systems: use of the fuel-cell waste heat in existing heating plant (see diagram); service connections sufficient for feeding electricity into the grid; balancing the electric load flow avoids expansions of the electricity grid; simultaneous generation and consumption of electricity and the large number of small fuel cells make additional peak-load and standby power stations unnecessary; heat storage in the heating system permits the use of the fuel-cell total output as a momentary power reserve for the national grid by centralised ripple control; additional investments in the gas supply network remain small. The application of fuel cells also enables savings to be made: mass production of small cells; commercial viability due to utilisation of waste heat even at low fuel-cell efficiencies, which also serve to encourage early use of this solution, and ruggedness of the fuel cells.

Optimal use and the value of water resources in electricity generation

Abstract: Econometric and dynamic programming analysis is used to derive optimal operating rules for water resources used in electricity generation. The methodology is applied to an actual mixed power system with interconnected thermal and hydro plants. Results obtained are compared with the electricity utility's operating practices. Short-run marginal costs and water values are also derived. The implications of these to efficient pricing of both electricity and water supply are discussed and net effective costs for new generating plants are derived. These costs are important in determining the optimal plant mix.

Electric load controller for vehicle

Abstract: PURPOSE: To prevent the exhaustion of battery power by installing a voltage detecting means for detecting the reduction of voltage of the battery mounted on a vehicle and installing a switch means which receives the voltage reduction detection signal and cuts off the supply of electricity into an electricity feeding line at least for a part of the electric load. CONSTITUTION: A fundamental electricity feeding line 2, the first and second electricity feeding lines 3 and 4 are wired with a battery 1 mounted on a vehicle, and the fundamental electricity feeding line 2 is connected with the battery 1 through an ignition switch 5, and electricity can be supplied mainly to a starter. The first electricity feeding line 3 is connected with the battery 1 through a switch means 8, and the electric load 9 such as room lamp and a radio set is connected with the electricity feeding line 3. A voltage detecting means 6 and a keyless entry means 7 are arranged in parallel in the second electricity feeding line 4. When the voltage detecting means 6 detects that the battery voltage reduces less than a prescribed limit voltage, the relay coil 14 of the switch means 8 is allowed to conduct to open a switch 15. COPYRIGHT: (C)1988,JPO&Japio

Wind-Generators in Hybrid Systems Powering Remote Telecommunication Sites in the Far North

Abstract: As indicated in the title this paper deals with the experience attained from operation of hybrid power systems (i.e. systems relying on multiple sources of energy to ascertain continuous operation of telecom equipment with one or more inactive power sources), incorporating wind generators in remote telecom stations located in an arctic environment. Although the functional layout of such systems will exhibit similarities disregarding location, this description is based on the specific layout of Norwegian/Scandinavian sites with special emphasis on the test sites operated by the Norwegian Telecommunications Administration (NTA), the sites being listed in Table 1. The hybrid systems under test are without exception relying on wind and/or solar energy as the primary power source, backed up by stationary (lead-acid) batteries and/or one or more fossil fuel-driven (mostly diesel) generators and a control unit that has a bilateral function, one of which being the switching between the different power sources when required, the second being an "intelligent" utilization of surplus or "waste" energy. It is self-evident that the focus in this test program is particularly on the reliability of system components prone to mechanical wear, i.e. the wind-generator and also the control system. The aim of this discussion is to extract the essential information from the experience gained so far and how this will affect further integration of similar systems.

New electric power technologies: cost and performance in the 1990s

Abstract: A number of developing electric power generating technologies are beginning to show considerable promise as future electricity supply options. This paper reviews OTA's perception of the probable cost and performance of such technologies in the 1990s; the technologies considered include atmospheric fluidized bed combustion (AFBC), integrated coal gasification combined cycle plants (IGCC), fuel cells, compressed air energy storage, advanced battery systems, photovoltaics, solar thermal, wind turbines, geothermal power plants, and load management systems. For the most part, at their current rate of development, these technologies are not likely to be in a position to contribute significantly to the US electricity supply until after the year 2000, but a variety of steps could accelerate their commercial deployment in the 1990s. 7 refs.