Closed loop tracking system using signal beam

摘要

The invention is a system and method for heliostat mirror control. Here, each heliostat mirror generates a low intensity “signal beam”, directed at an angle off from the heliostat mirror's high intensity and sensor blinding “main beam” of reflected solar energy. The low intensity signal beams may be created by reflecting a small portion of the incident solar light at an angle from the main beam, by reflected artificial light, or from lasers shinning onto mirrors from known locations. The signal beams are detected by optical sensors mounted way from the main heliostat receiver focus, and can be used in a closed loop control system to efficiently ensure that individual heliostat mirrors in a heliostat array accurately track sunlight and direct the sunlight to a central receiver. Because heliostat mirrors need not be taken “off sun” for positioning, the system allows heliostat arrays to be run at high efficiency.

主权项

1. A method of positioning a heliostat mirror, within an array of one or more heliostat mirrors, to reflect incident sunlight so that a main beam is directed onto a desired region of a receiver, said method comprising:
causing a heliostat mirror to emit a low intensity signal beam to one or more digital cameras placed in a location other than a receiver; said low intensity signal beam being emitted at an angle other than that of a main beam; determining a relationship between said low intensity signal beam and said main beam; and using said low intensity signal beam received on said digital cameras to determine if said heliostat mirror is positioned so that said main beam of incident sunlight reflected from said heliostat mirror converges onto a desired region of a receiver; wherein an optical element is coupled to said heliostat mirror, said optical element producing said low intensity signal beam by transforming a fraction of said incident sunlight to said low intensity signal beam emitted at an angle offset from said main beam.