Directional drilling today is a manual process characterized by monitoring drilling parameters and trends, predicting the future wellbore trajectory and adjusting steering parameters as required. When drilling with a rotary steerable system (RSS) in the bottom-hole assembly (BHA), the trajectory control system is distributed between surface and downhole. The surface control makes use of downhole measurements and capabilities of the rotary steerable BHA, and in turn is used to control the downhole components, forming a ‘directional drilling control loop’ and allowing the efficient drilling of a quality wellbore. Traditionally, the directional driller assumes the surface control, whereas downhole control was executed by the RSS-BHA allowing to drill certain parts of a section automatically. With the advent of automation, the surface control can be executed by a control system.
This paper introduces a new automated trajectory drilling service for a rotary steerable system. The system is capable of predicting the wellbore trajectory, deriving steering proposals to follow the planned trajectory closely or steer back to plan, and submitting those steering downlinks automatically to the downhole RSS with the directional driller observing the system. The paper explains the underlying control methodology and the automation system architecture. Furthermore, operational considerations such as handling of formation disturbances are discussed. The concept of embedding the driller and directional driller in the decision-making workflow is outlined. Finally, the performance of the automated trajectory drilling system is assessed and field test results from two case studies are presented, where up to 98 % of a single wellbore has been drilled automatically. To date, a total of 3,926 m have been drilled automatically with the automated drilling system.
This paper presents a dynamic core loss model for active loss control of permanent magnet synchronous machines. Deadbeat-direct torque and flux control (DB−DTFC) enables direct control of torque and stator flux linkage over each switching period. Total machine loss can be minimized by selecting the optimal flux level in every sampled time instant. Reliable models for dynamic copper and core loss are an essential requirement for this optimizing task. This paper presents an analytical dynamic core loss model in switching period time-domain, using stator flux linkage as the manipulated input variable. Combining numerical and analytical calculation methods is used to create an easy and practical approach to estimate core loss components based on stator flux linkage without running FEA calculations for every time instant. Additional effects like high frequency eddy current loss in electrically conducting permanent magnets as well as spatial harmonic content are taken into account.
This paper presents time optimal torque control in overmodulation and switching level loss minimization control of an induction machine (IM) and an interior permanent magnet synchronous machine (IPMSM) via deadbeat, direct torque and flux control (DB-DTFC). Using DB-DTFC, the stator flux linkage can be manipulated each PWM cycle to minimize losses during normal operation. Due to voltage limits during overmodulation it may take a sequence of incremental torque commands over several PWM periods to achieve a desired air-gap torque that is physically infeasible in one step. In that case, the DB control becomes finite settling step (FSS) control in which the steps may be optimized using time optimal strategies. In this paper, a time optimal FSS control using a DB-DTFC solution during overmodulation and a loss minimizing DB-DTFC solution over the full torque-speed operating space are proposed and evaluated for IM and IPMSM drives.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.