Accurate determination of corona power loss on
HVDC power lines usually represents a difficult problem for
utilities. This is due to the numerous uncertainties associated
with the corona phenomena. Such uncertainties may include line
clearances values, conductor surface coefficient and atmospheric
conditions. Interval mathematics provides a tool for the practical
implementation and extension of the “Unknown but Bounded”
concept. The paper presents the application of Interval
Mathematics to, rigorously, address uncertainties associated with
corona losses. While several methods exist to determine corona
power loss, these methods usually require data which may be
uncertain in nature. To account for such uncertainties, the
interval mathematics is developed with the integration of input
parameters’ uncertainties, in interval format, into the governing
expressions earlier by several electric utilities. The effects of
uncertain inputs within the proposed model are examined for
various assumed levels of overall uncertainties. To assess the
relative contribution of each uncertain input, an interval
sensitivity analysis is carried out. Electric field upon the
conductor surface, corona current and corona power loss values
are calculated using the traditional single point numbers as well
as interval numbers. The values from the two methods are
compared to prove the validity of interval analysis to, practically,
model uncertainties associated with HVDC transmission lines
corona loss analysis. Successful implementation of the proposed
method is described for two geometries; monopolar and bipolar
dc lines. |
