Development of a voltage regulator for solar photovoltaic cathodic protection system

The voltage regulator is one of the main elements from which depends the reliability and
the efficiency of the photovoltaic system. Among the large number photovoltaic applications, we are
interested by the cathodic protection, it’s recognized as one of the most efficacious means of the
active prevention against the corrosion.
Photovoltaic cathodic protection is one of the possible solutions for the structures subjected to
corrosion, mainly in oil and gas industries [Tanasescu et al., 1988]. In this paper, the study about the
design of a voltage regulator with variable output for solar photovoltaic cathodic protection has
been carried out. Our system is based on two microcontroller controlled DC/DC converters : the first
one is a buck used to match the maximum power point voltage of the solar panel to the battery
charging voltage ; and the second one is a buck-boost used between the batteries and the load in
order to adapt the regulator at any cases of the cathodic protection stations.
Usually, cathodic protection systems are working with constant current output which is the necessary
condition to procure immunity voltage of the structures that strictly required preventing corrosion
from occurring. The major difficulty to achieve this goal is the variations of the surrounding medium
resistivity to overcome this difficulty, we propose an automatically adjustment of the output voltage
of the buck-boost converter to feed the load (sacrificial anode-protected structure) thanks to the
microcontroller by generating the required duty cycle by way of its PWM output.
The developed system allows the solar panel to operate at its maximum power point output (MPP),
when the MPP changes, the microcontroller changes the conversion ratio (duty cycle) of the buck
circuit to keep the solar panel at its MPP. The buck steps higher voltage panel down to the battery
charging voltage. In this paper, the study about the design of this voltage regulator with variable
output for solar photovoltaic cathodic protection has been described.

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