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.
Heat Transfer Analysis in Cooling System of Hydropower’s Generator
Cooling process of power plant generator is handled via air-cooled radiators in which the cooling water is supplied from lake with its water temperature varies from season to season. In this study, the effect of temperature fluctuations of cooling water entering the cooling system has been examined via analysis of energy (NTU method) and exergy. The exergy analysis has been done by definition of efficiency coefficient for exergy of cooling media (water) and heating media (air). Besides, the effect of changing the cooling water temperature and flow rate entering the radiators on the cooling system performance has been studied. The results revealed the generator cooling system performance level held sufficient till the temperature of inlet water was kept under 293 k (20°C). On one hand, when the temperature of cooling water at the inlet rises to 12°C, the rate of heat exchange at radiators falls up to 34.3%. On the other hand, by water temperature passing the 12°C limit, the efficiency of cooling media exergy falls to 78% leading to efficiency rise in radiators’ heating media exergy level to 61%. According to the results of this study, changing flow rate of cooling media up to 40% gives rise to the efficiency coefficient of radiators’ cooling media exergy level to about 18.7%. While it does not affect the efficiency level of energy at radiators, the flow rate rise of cooling media may not be considered as a way to give rise to efficiency level of radiators.