Abstract: A power transmission system and method for transmitting power over a three-phase power system on a multi-conductor power cable between a surface and a sub-surface location are provided. A surface system includes a power supply providing a direct current (DC) power signal to the power cable. A sub-surface system includes a downhole system coupled to a Y-point of a downhole motor. The downhole system is configured to be powered by (i) the DC power signal provided by the surface system, (ii) alternating current (AC) power drawn from the Y-point, and (iii) a combination of the DC power and the AC power. The downhole system is powered by the DC power when the power cable does not have an insulation fault, and the downhole system is powered by the AC power or the combination of the DC power and the AC power when the power cable has an insulation fault.

Abstract: An example linear pumping system suitable for small size and low flow rate operation. The system includes a pump casing that encloses a linear motor and one or two (an upper and lower) pumps. The pump casing may include an upper fluid inlet port, a lower fluid inlet port, and a fluid-outlet port. The linear motor includes a stator and a mover, where the mover includes an upper plunger portion and a lower plunger portion and is configured to move alternately up and down relative to the stator. The upper and lower pumps positioned on both sides of the mover may each include a pump chamber, a fluid inlet valve, and a fluid outlet valve. In operation, hydraulic pressure from the upper and lower pump outlet valves causes fluid within an interior cavity of the pump casing to be expelled through the fluid outlet port. The motion of the mover can be controlled using pressure and/or plunger position measurements.

Abstract: A power transmission system and method for transmitting power over a three-phase power system on a multi-conductor power cable between a surface and a sub-surface location are provided. A surface system includes a power supply providing a direct current (DC) power signal to the power cable. A sub-surface system includes a downhole system coupled to a Y-point of a downhole motor. The downhole system is configured to be powered by (i) the DC power signal provided by the surface system, (ii) alternating current (AC) power drawn from the Y-point, and (iii) a combination of the DC power and the AC power. The downhole system is powered by the DC power when the power cable does not have an insulation fault, and the downhole system is powered by the AC power or the combination of the DC power and the AC power when the power cable has an insulation fault.