Diagnostic Symptoms of Corona Audible Noise in Continuous Monitoring Systems

Random nature of corona processes in UHV power lines and the accompanying
noise is the reason that in practice the best determination of acoustic parameters,
necessary for the noise evaluation, is obtained from the continuous monitoring procedure.
However because of considerable fluctuations (both the useful signal part
and the interfering components), careful selection of monitored parameters is necessary
to enable a possibility of automatic determination of the parameters that are
required for long-term evaluation of corona noise.
In the present work a practical realization is shown for estimation of corona
noise parameters, based on the data obtained from continuous monitoring stations,
making use of the statistical spectra measurement and characteristic features of
corona process acoustic signal.
Selected results are presented from continuous monitoring of corona noise generated
at a 400 kV power line, with special attention focused on definitions of the
measured quantities, which enable automatic estimation of the basic factors required
for noise evaluation. Accompanying monitoring of environmental conditions,
including humidity, precipitation intensity and fog density, that are well correlated
with the corona process intensity, which might definitely increase the filtration efficiency
of environmental disturbances and on the other hand, it enables verification
of calculation methods applied to corona noise.
The paper also contains a description of practical approach to selection signal
parameters of corona noise in continuous monitoring stations.