Steel lattice towers are also used in electronic and communication industries for communication of microwave signals through different types of antennas. Several antennae are fixed on the tower in different directions at different heights as per the requirement and usage. The antenna positions decide the height of the tower. Symmetrical cross sections are preferred for microwave towers due to reversal of wind direction. Generally steel lattice towers with square or triangular plan are used for microwave towers. Angle sections and tubes are commonly used for the fabrication of these towers. Microwave towers are generally self-supporting steel lattice towers. Guyed towers are also used for microwave communication, but are least preferred for supporting heavy disc antennae. Wind load on the tower body and antennae is the major load on the structure besides the self-weight of the tower. Microwave towers are generally supported either at ground or at rooftop of some buildings. The tip deflection of the tower is a governing parameter for the functional requirement. Typical configuration of a 102-m high microwave tower is shown in Figure. The tower is triangular in plan. The two-dimensional and three-dimensional views of the tower are shown.
Primary, Secondary and Tertiary Frequency Control in Power Systems Author: Engr. Aneel Kumar Keywords: frequency control, primary frequency control, automatic generation control (AGC), tertiary control, load-frequency control, grid stability. Frequency control keeps the power grid stable by balancing generation and load. When generation and demand drift apart, system frequency moves away from its nominal value (50 or 60 Hz). Grids rely on three hierarchical control layers — Primary , Secondary (AGC), and Tertiary — to arrest frequency deviation, restore the set-point and optimize generation dispatch. Related: Power System Stability — causes & mitigation Overview of primary, secondary and tertiary frequency control in power systems. ⚡ Primary Frequency Control (Droop Control) Primary control is a fast, local response implemented by generator governors (dro...
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