Application of Broadcast FM for Utility Energy Management Communications
Technological and economic aspects of various approaches to electric utility Energy Management communications for remote control are discussed. Communication systems employing radio frequency (RF) transmission techniques are treated in some detail with comparisons being made between narrow- band VHF transmitter systems, those systems utilizing a portion of AM broadcast radio channels and systems using a portion of FM broadcast radio channels. Finally, typical utility energy management applications of these-systems are discussed.
A low-cost microcomputer based direct load control scheme for small electric utilities
Abstract A low-cost microprocessor based direct load control scheme is described. The scheme is particularly suitable for small- to medium-sized public utilities which do not possess large financial resources to implement a large-scale SCADA based load management system. The system is designed around the 8-bit 68HC11 microcontroller manufactured by Motorola. The hardware consists of two basic systems: the transmitter and the receiver. The transmitter consists of a PC, and HC11 Evaluation Board and a radio transmitter. The receiver consists of the radio receiver and an HC11 running in single-chip mode. The system uses an addressing scheme to control up to four loads at each of 4095 different receiver sites. It uses redundant data transmission to ensure error-free operation.
Experimental Study for a Double-Glazed Forced-Flow Solar Collector/Regenerator
Experimental study of a double-glazed forced-convection solar collector/regenerator for absorption solar cooling is presented. The south facing experimental solar collector/regenerator with 10 deg slope is located at Kaohsiung, Taiwan at 120{degree}19minutesE longitude and 22{degree}34minutesN latitude. The size of the collector is 1 m wide and 7 m long with an effective regeneration area of 0.9 m by 6 m. Previous study for single-glazed forced-convection solar collector/regenerator operated at the same location has shown to have a best day-average efficiency of 17%. In order to raise the system performance, a double-glazed collector/regenerator is constructed such that air can be preheated in the upper channel flow. The preheated air is then conducted into the lower channel where it contacts with the film flow of solar heated lithium-chloride solution and regenerates the solution by carrying out the evaporated water vapor. The preheated air has lower relative humidity but the same humidity ratio since it is sensibly heated. Therefore, the regeneration driving potential is increased. The present study shows that the best day-average efficiency can reach 20% which increases the feasibility of the open-cycle absorption solar cooling system. Effects of controlling parameters on the collector/regenerator performance are studied, and heat and mass transfer correlationsmore » are also presented for design purposes.« less