Electric power

About: Electric power is a research topic. Over the lifetime, 73036 publications have been published within this topic receiving 636991 citations.

Hybrid energy off highway vehicle electric power storage system and method

Abstract: An electrical energy capture system for use in connection with a hybrid energy off highway vehicle system of a off highway vehicle. The hybrid energy off highway vehicle system includes an off highway vehicle, a primary power source, and an off highway vehicle traction motor propelling the off highway vehicle in response to the primary electric power. The off highway vehicle traction motor has a dynamic braking mode of operation generating electrical energy. The electrical energy capture system includes an energy management processor carried on the off highway vehicle. The capture system also includes an off highway vehicle electric generator connected to and driven by the primary power source for selectively supplying primary electric power, wherein the generator is responsive to said processor. An electrical energy storage device is carried on a off highway vehicle and is in electrical communication with the off highway vehicle traction motor. The storage device is responsive to the processor, selectively stores electrical energy generated in the dynamic braking mode, and selectively provides secondary electric power from said stored electricity electrical energy to the off highway vehicle traction motor. The off highway vehicle traction motor is responsive to the secondary electric power. The processor provides a first control signal to the electrical energy storage device to control the selective storing of the electrical energy generated in the dynamic braking mode, and to control the selective providing of secondary electric power to the off highway vehicle traction motor. The processor also provides a second control signal to the generator for controlling the selective supplying of primary electric power to the off highway vehicle traction motor.

Shape of the microgrid

Abstract: Shape of the Microgrid Chris Marnay, F Javier Rubio, and Afzal S Siddiqui Ernest Orlando Lawrence Berkeley National Laboratory C_Marnay@lbl.gov * tel: +1.510.486.7028 preliminary summary of presentation to be given in the panel Role of Distributed Generation in Reinforcing the Critical Electric Power Infrastructure at the IEEE Winter Meeting, Columbus, OH, 31 January 2001 Restrictions on expansion of traditional centralized generating and delivery systems may be becoming so tight in the industrialized countries that they cannot reasonably be expected meet future electricity demand growth at acceptable cost. Meanwhile, technological advances, notably improved power electronics that permit grid interconnection of asynchronous generation sources, is tilting the economics of power generation back towards smaller scales, thereby reversing a century long trend towards the central control paradigm. Special power quality requirements or opportunities for combined heat and power applications make on-site generation an even more attractive option for customers. The existence of a significant amount of electricity sources dispersed throughout the low voltage distribution system could create a power system quite different to the one we are familiar with and creating it offers significant research and engineering challenges. Moreover, the electrical and economic relationships between customers and the distribution utility and among customers may take forms quite distinct from those we know today. For example, rather than devices being individually interconnected in parallel with the grid, they may be grouped with loads in a semi-autonomous neighborhood that could be termed a microgrid. A microgrid is a cluster of small (by the standards of current power systems, e.g. < 500 kW) sources, storage systems, and loads which presents itself to the grid as a legitimate single entity. The heart of the microgrid concept is the notion of a flexible, yet controllable electronic interface between the microgrid and the familiar wider power system, or macrogrid. This interface essentially isolates the two sides electrically; and yet connects them economically by allowing delivery and receipt of electrical energy and ancillary services (EE&AS) at the interface. From the customer side of the interface, the microgrid should appear as an autonomous power system meeting the power quality and reliability requirements of the customer. Such issues as local voltage, reliability, losses and quality of power should be those that support the customers' objectives. From the macrogrid side, however, the microgrid should appear as a legitimate entity akin to current interconnected generators or loads. A key distinction between microgrids and our familiar arrangements is the expanded role of electricity endusers in determining the pattern of development of the overall power system, which must not only accommodate purchases and sales of EE&AS to and from established markets but also contractual agreements between microgrids. Fundamentally, the characteristics and capabilities of the microgrid will be determined by its internal requirements together with the technical, economic, and regulatory opportunities and constraints it faces, and not by established objectives for capacity expansion and reliability of the macrogrid. The goal of Consortium for Electric Reliability Technology Solutions (CERTS) work underway at the Berkeley Lab is to anticipate possible patterns of microgrid development that can help focus research efforts on the key technical problems that must be solved to enable microgrid deployment. C:\WINNT\Profiles\jose\Desktop\LBNL-47451.doc

Peak power shaving apparatus and method

Abstract: Utility charges associated with peak electrical power demands constitute an increasing portion of utility bills associated with large commercial consumers of electricity. The instant invention provides an apparatus for reducing the peak electrical demand of a predetermined user operational unit from an electrical power distribution network by controllably operating at least one secondary electrical generator associated with the operational unit in parallel with the utility power distribution network. The secondary electrical generator includes a switch for connecting the generator in parallel with the utility network in response to receiving a transfer command signal. A transducer senses the actual peak power demand of the operational unit from the utility network and produces a demand signal having a value responsive to the sensed actual peak power demand. A memory element controllably stores a plurality of control parameters including a demand setpoint value. A logic device controllably produces the transfer command signal and connects the secondary electrical generator in parallel with the utility distribution network in response to the value of the demand signal exceeding the value of the demand setpoint. The logic device controls the secondary electrical generator to produce only the amount of power necessary to maintain the demand signal at or below the demand setpoint value.

Hybrid fuel battery system and the operation method thereof

Abstract: A hybrid fuel cell system including a fuel cell for generating electric power by reacting fuel gas and oxidant gas, current restricting structure for restricting an output current of the fuel cell, a storage cell connected parallel to a series circuit comprising the fuel cell and the current restricting structure for helping the fuel cell to supply electric power to an external load, external load fluctuation detecting structure for detecting a fluctuation in the current demanded by the external load and current limitation adjusting structure for following the fluctuation in the current demanded by the external load by changing the restriction of the output current of the fuel cell which is made by the current restricting structure, with the passage of time.

An excellent operating point tracker of the solar-cell power supply system

Abstract: When the solar array is used as an input power source, the excellent operating point tracker is often employed to exploit more effectively the solar array as an electric power source and to obtain the maximum electric power at all times even when the light intensity and environmental temperature of the solar array are varied. Usually, the excellent operating point is determined by computing the electric power from the solar-array power supply with a microcomputer, digital signal processor, etc. However, such a method has the following problems: 1) complex control-circuit configuration; 2) high cost; and 3) low control speed. From this viewpoint, this paper proposes a new excellent operating point tracker of the solar-cell power supply system, in which inexpensive p-n junction diodes are used to generate the reference voltage of the operating point of the solar array. Using the proposed method, the high degree of the solar-array excellent point tracking performance can be obtained even when the light intensity and environmental temperature of the solar array are varied. Furthermore, this paper provides the operation principle, design-oriented analysis, etc., of the proposed solar-cell power supply system.