Variable Frequency Drive Archives - Production Technology

Compared to conventional ESP installations with constant motor speeds, installations running at variable frequencies have several advantages. The most important benefit of a Variable Speed Submersible Pumping System is the wide flexibility of the variable frequency ESP system that permits perfect matching of the lift capacity of the ESP system and the well’s productivity. Therefore, it operates over a much broader range of capacity, head, and efficiency.

NB: Variable Frequency Drive basics (also, named: Variable Speed Drive) are presented and discussed in the article “Variable Frequency Drive Basics”.

Since a submersible pump motor is an induction motor, its speed is proportional to the frequency of the electrical power supply. This relationship between variables involved in pump performance (such as head, flow rate, shaft speed) and power is known as “Affinity Laws” (also called “Pump Laws”).

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Step 8 – Downhole and Surface Accessory Equipment

By Islam Fetoui | 16 June 2017 - 19 h 32 min |7 September 2017 9 Step Design Procedure

Downhole Accessory Equipment:

Motor Lead Extension (MLE):

API RP 11S4 defines the Motor Lead Extension as a “special power cable extending from the pothead on the motor to above the end of the pump where it connects with the power cable. A low-profile cable (flat configuration) is usually needed in this area due to limited clearance between the pump housing and the well casing”. It is recommended to select a length at least 6 ft. (1.8 m) longer than the upper end of the pump. The length of MLE has to be select in a way to avoid a splice over a tubing collar. Doing so could allow the cable to catch on the wellbore casing and damage the equipment.

Banding Cable Protectors:

Cable protectors are used to protect the Motor Lead Cables from damage during installation, operation and pulling. The figures below show an example of cable protectors.

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Variable Frequency Drive Basics

By Islam Fetoui | 3 April 2017 - 23 h 42 min |8 September 2017 Artificial Lift, Equipment & Technology, ESP

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In this article, Variable Frequency Drive (also, named: Variable Speed Drive) basics are presented in a simple and easy way with explanation graphs. To understand how the Frequency Speed Controller operates, it is necessary to understand how the VSD supplies variable voltage and frequency for speed control.

The below block diagram illustration depicts a typical three-phase AC variable speed drive system. It has three main components: an Operator Control, a Drive Controller, and an AC Motor.

An Operator Control device provides a means to start and stop the motor and adjust the operating speed. The Drive Controller consists of a variety of components that work together to convert an AC input into a frequency and voltage output necessary to change the speed of an AC motor.

Main sections of a Variable Frequency Drive:

The converter section:

This section converts the incoming 3-phase AC voltage to DC voltage. The converter is essentially a 3-phase, full wave rectifier with Silicon Control Rectifiers, a specialized type of control diode, in the bridge.

The following video explains what SCR is and how it works:

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ESP Pump:

Pump Intake:

Seal Section:

ESP Motor:

ESP Cable:

Motor Controller:

Transformer:

Wellhead Equipment:

Accessory Equipment:

Downhole Accessory Equipment:

Motor Lead Extension (MLE):

Banding Cable Protectors:

Main sections of a Variable Frequency Drive:

The converter section:

This section converts the incoming 3-phase AC voltage to DC voltage. The converter is essentially a 3-phase, full wave rectifier with Silicon Control Rectifiers, a specialized type of control diode, in the bridge.

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