Energy and Climate
Energy and ClimateAbout Energy and Climate (EC)EC Publications

EC Publications

CREATING DYNAMIC EQUIVALENT PV CIRCUIT MODELS WITH IMPEDANCE SPECTROSCOPY FOR ARC FAULT MODELING « Manual « Downloads

AttributeValue
Date postedApril 9, 2012
Downloaded54 times
CategoriesManual, Renewable Energy, Systems Modeling, Photovoltaic

Description

Article 690.11 in the 2011 National Electrical Code
®
(NEC
®
) requires new photovoltaic (PV) systems on or
penetrating a building to include a listed arc fault
protection device. Currently there is little experimental or
empirical research into the behavior of the arcing
frequencies through PV components despite the potential
for modules and other PV components to filter or attenuate
arcing signatures that could render the arc detector
ineffective. To model AC arcing signal propagation along
PV strings, the well-studied DC diode models were found
to inadequately capture the behavior of high frequency
arcing signals. Instead dynamic equivalent circuit models
of PV modules were required to describe the impedance
for alternating currents in modules. The nonlinearities
present in PV cells resulting from irradiance, temperature,
frequency, and bias voltage variations make modeling
these systems challenging. Linearized dynamic
equivalent circuits were created for multiple PV module
manufacturers and module technologies. The equivalent
resistances and capacitances for the modules were
determined using impedance spectroscopy with no bias
voltage and no irradiance. The equivalent circuit model
was employed to evaluate modules having irradiance
conditions that could not be measured directly with the
instrumentation. Although there was a wide range of
circuit component values, the complex impedance model
does not predict filtering of arc fault frequencies in PV
strings for any irradiance level. Experimental results with
no irradiance agree with the model and show nearly no
attenuation for 1 Hz to 100 kHz input frequencies.

Comments are closed.