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The optical
quality of the heliostat field and the homogeneity of the flux density
distribution on the receiver are key factors for the energy efficiency
and economics of solar tower power plants. To achieve reliable, cost-effective
improvements in heliostat field manufacture, erection and operation in
solar tower power plants, new and improved measurement methods are
needed.
In this project, DLR is developing a new optical measurement method that
simplifies and optimizes erection and canting of heliostats and assures
their optical quality before commissioning of the solar field. This
method is based on the reflection of regular patterns in the mirror
surface and their distortions due to mirror surface errors. This highly
accurate, high spatial-resolution measurement is also very fast, making
automatic measurement of entire heliostat fields possible in a
reasonable time. Figure 5.6 shows an example of heliostat slope errors
measured at the PSA.
Additional optical measurement methods are being developed to
automatically check the tracking accuracy of the heliostat field during
operation and further increase the efficiency of solar receivers.
Existing measurement systems for temperature and flux density
distribution on the surface of small-scale prototype receivers have been
extended to monitoring and control of these parameters on large-scale
receivers during operation of commercial power plants.
Based on the knowledge acquired in this project, relevant parameters for
the assessment of heliostat fields during design, manufacturing and
operation have been defined and appro-priate methods for their
measurement proposed. |
