As the old saying goes, 'Two heads are better than one'. When it comes to electric drives for drilling rigs, the situation is quite different. South Ural State University researchers developed an energy-efficient differential electric drive for drilling rigs. It is able to replace two electric motors, which are typically used for drilling rigs.
"Currently drilling rigs use either two engines or a bulky gearbox, like in a car," explains Nikita Savosteenko, senior lecturer of the Automated Electric Drive Department. “The efficiency of such boxes is very low. When it comes to using two engines, the efficiency is high, as it is with the operation of our development, but we also have an advantage: reduced weight and dimensions. This is important, because the drilling rig itself is extremely heavy, it weighs over 100 tons. By reducing the number of engines to one unit we reduce the weight of the rig and increase the free space on it. This free space can be used for necessary equipment, for example, for special microclimate enclosures. As a rule, drilling rigs are used in the Far North (if we are talking about oil production), and it is difficult to maintain the necessary operating temperature of electrical equipment.”
In addition to increasing the efficiency and reducing the mass and overall dimensions of the motors, the scientists' development makes it possible to reduce the cost of purchasing electrical equipment and improve the reliability of the entire system. Nikita Savosteenko explains why:
"The mechanics themselves say that the more mechanisms there are, the less reliable the system is. The probability of one of two motors breaking down is greater than the probability of a single motor breaking down!"
The biggets volumes of oil production in Russia today are in the Khanty-Mansi Autonomous District. This territory is located in the Far North region. The electric drive developed by the department’s staff is able to operate at low temperatures of about 60 degrees below zero. Employees of the Department of Automated Electric Drive’s Power Engineering Faculty of the Institute of Engineering and Technology have been working on developments in the field of electrical engineering for many years. During his postgraduate studies, senior lecturer Nikita Savosteenko prepared about 30 articles for different scientific journals; now the young scientist is writing his dissertation on the use of electric motors. The SUSU staff member explains how they managed to replace two motors with one.
“What is a differential electric drive? This means that a differential planetary gearbox is used in the mechanical part of the motor. Differential means that its kinematic scheme can be changed. In other words, the gear ratio of the reductor can be changed mechanically,” says Nikita Savosteenko. “With two engines, one of them has high speed, but creates a low load torque, while the other engine, on the contrary, has low speed but high torque. So, by changing the kinematic scheme, we were able to replace two engines with one and achieve with it what had only been previously possible with two engines.”
The scientists have patented their development, but two or three years are needed for its implementation. In the near future, they will prepare a laboratory model, on which it will be possible to evaluate the performance of the differential electric drive. The electric motor must also undergo field testing. After this, the team will be able to present their results to interested companies. And there is already interest in the electric motor.