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73 results about "Zone System" patented technology

The Zone System is a photographic technique for determining optimal film exposure and development, formulated by Ansel Adams and Fred Archer. Adams described the Zone System as "[...] not an invention of mine; it is a codification of the principles of sensitometry, worked out by Fred Archer and myself at the Art Center School in Los Angeles, around 1939–40."

Pattern analysis-based photovoltaic power station multi-unit system low-frequency oscillation suppressing method

The invention discloses a pattern analysis-based photovoltaic power station multi-unit system low-frequency oscillation suppressing method. The pattern analysis-based photovoltaic power station multi-unit system low-frequency oscillation suppressing method comprises the steps of 1) establishing a grid-connected photovoltaic power station dynamic model comprising a photovoltaic array, an inverter and a control module of the inverter; 2) establishing a photovoltaic power station-contained multi-unit power system state equation and a linearized model of the photovoltaic power station-contained multi-unit power system state equation; 3) taking a four-unit two-area system as an analyzing example to perform pattern analysis on the linearized model; 4) designing a photovoltaic wide-area damping controller. The pattern analysis-based photovoltaic power station multi-unit system low-frequency oscillation suppressing method can effectively achieve damping control of a photovoltaic power generation system, reduce negative effects on system safety and stability levels which are possibly led to by photovoltaic grid connection, and improve receptivity of an interconnected electric power system to the photovoltaic power generation system.
Owner:NANJING UNIV OF SCI & TECH

Direct current electrical controls for heating systems

A method and apparatus for controlling the normal operation of a hydronic heating system, (including AC powered, gas-burning hot water boiler, multi-zone systems) using a DC power source, such as battery power, as the primary continuous source of electricity. Control functions minimize the consumption of electric power during normal operation, and eliminate standby electric consumption in order to extend the life of the batteries and maximize the run-time of the heating system. A DC to DC converter supplies low voltage DC power to the zone thermostats, and also supplies the proper voltage through zone relays to operate DC zone pumps. By allowing the use of DC power for the thermostats and zone pumps, the system eliminates the need for transformers, zone valves, and AC circulators, resulting in a large savings in electrical consumption and the elimination of the standby electric demand ("phantom load") common in conventional hydronic heating systems. A DC to AC inverter is dedicated to supply AC power for a hydronic (hot water) boiler. The inverter is switched on by relays only when needed, thereby eliminating the "phantom electric load" consumed by most boilers when standing by. A time delay relay circuit allows the boiler to go through its proper shutdown sequence before power is removed. This control system does not require any internal modification to the other heating system components.
Owner:STICKNEY BRISTOL L +1
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