Method and system for controlling powered anode drive level

1. A method of controlling a powered anode providing cathodic protection in a vessel, the method comprising:

varying an electrical power input driving a powered anode through a range of values of a first electrical parameter, the range defined by an upper range limit and a lower range limit;

measuring values of a plurality of electrical parameters of the electrical power input during the varying;

plotting a trace of values of a first electrical parameter of the plurality of electrical parameters of the electrical power input with corresponding values of a second electrical parameter of the plurality of electrical parameters of the electrical power input;

determining a slope of the trace at a plurality of points on the trace;

identifying a discontinuity on the trace; and

applying the electrical power input that corresponds to the identified discontinuity to the powered anode to provide cathodic protection to the vessel.

2. The method of claim 1 , wherein identifying a discontinuity on the trace comprises identifying a point on the trace where at least one of a change in a value of the slope exceeds a predetermined slope threshold range and a change of polarity of the value of the slope occurs.

3. The method of claim 2 , further comprising when at least one of a change in the value of the slope is within the predetermined slope threshold range and a change of polarity of the value of the slope does not occur, modifying at least one of the upper range limit and the lower range limit such that a difference between the at least one of the upper range limit and the lower range limit is increased.

4. The method of claim 2 , wherein applying the electrical power input of a first electrical parameter to the electrical power input comprises applying the electrical power input of a first electrical parameter to the electrical power input when at least one of a change in a value of the slope exceeds the predetermined slope threshold range and a change of polarity of the value of the slope occurs.

5. The method of claim 1 , wherein applying the electrical power input that corresponds to the identified discontinuity comprises applying the electrical power input that corresponds to a point on the trace where at least one of a change in a value of the slope exceeds a predetermined slope threshold range and a change of polarity of the value of the slope occurs.

6. The method of claim 1 , wherein varying the electrical power input comprises modifying at least one of the upper range limit and the lower range limit such that a difference between the applied electrical power input and at least one of the upper range limit and the lower range limit is reduced.

7. The method of claim 1 , wherein varying the electrical power input comprises modifying at least one of the upper range limit and the lower range limit such that a difference between the at least one of the upper range limit and the lower range limit is reduced.

8. A powered anode drive control system for providing cathodic protection comprising:

an anode drive power supply;

a powered anode positionable in a fluid-filled vessel and electrically couplable to the anode drive power supply; and

an anode drive controller comprising one or more processors communicatively coupled to one or more memory devices, the one or more processors communicatively couplable to an anode drive current sensor and an anode drive voltage sensor communicatively coupled to the anode drive controller and the anode drive power supply, the one or more processors configured to:

vary an electrical power input driving the powered anode through a range of values of a first electrical parameter, the range defined by an upper range limit and a lower range limit;

measure a current value of a second electrical parameter of the electrical power input while the electrical power input is being varied;

determine a slope between the measured current values of the first and corresponding second electrical parameters and measured previous values of the first and second electrical parameters;

compare the determined slope to a predetermined slope threshold range; and

apply the current value of a first electrical parameter to the electrical power input when at least one of a change in a value of the slope exceeds the predetermined slope threshold range and a change of polarity of the value of the slope occurs to provide cathodic protection to the fluid-filled vessel.

9. The powered anode drive control system of claim 8 , wherein the one or more processors are further configured to vary an electrical power input driving the powered anode between an upper range limit and a lower range limit.

10. The powered anode drive control system of claim 8 , wherein the one or more processors are further configured to modify at least one of the upper range limit and the lower range limit such that a difference between the applied current value and at least one of the upper range limit and the lower range limit is reduced.

11. The powered anode drive control system of claim 8 , wherein the one or more processors are further configured to when at least one of the change in the value of the slope is within the predetermined slope threshold range and a change of polarity of the value of the slope does not occur, modify at least one of the upper range limit and the lower range limit such that a difference between the at least one of the upper range limit and the lower range limit is increased.

12. The powered anode drive control system of claim 8 , wherein a discontinuity in the slope comprises a change in a value of the slope that exceeds a predetermined slope threshold range and a change of polarity of the value of the slope occurs.

13. The powered anode drive control system of claim 12 , wherein the one or more processors are further configured to:

determine an average value of the slope between the measured current values of the first and corresponding second electrical parameters and measured previous values of the first and second electrical parameters while the electrical power input driving the powered anode is varied between the upper range limit and the lower range limit; and

store the average slope value for use in locating a discontinuity in the slope.