# US 2020/0400007 A1 · Top drive system dynamics health check tool > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0400007 A1 - Document ID: US20200400007A1 - Status: Published application - Kind: A1 - Application number: 16/975,219 - Filed: 2019-02-25 - Published: 2020-12-24 - Earliest claimed: 2018-02-23 - Assignees: Schlumberger Technology Corporation - Applicants: Schlumberger Technology Corporation - Inventors: Jian WU; Nathaniel WICKS - Web page: https://patentgrep.com/patent/US20200400007A1 ## CPC - E21B 44/04: in response to the torque of the drive {; Measuring drilling torque (E21B44/06 takes precedence; measuring stresses in a well bore pipe E21B47/007)} - H02P 21/0017: {Model reference adaptation, e.g. MRAS or MRAC, useful for control or parameter estimation} - E21B 3/022: {Top drives} - E21B 19/16: Connecting or disconnecting pipe couplings or joints (E21B19/20 takes precedence) - E21B 41/00: Equipment or details not covered by groups E21B15/00 - E21B40/00 - E21B 44/00: Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions - E21B 49/003: {by analysing drilling variables or conditions (E21B49/005 takes precedence; systems specially adapted for monitoring a plurality of drilling variables or conditions E21B44/00)} - G05B 17/02: electric - H02P 6/34: Modelling or simulation for control purposes - H02P 29/024: Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) ## Abstract A model of a control loop for a variable-frequency drive (VFD) and a top drive (TD) is generated. The VFD and the TD are part of a VFD-TD system of a well drilling system. Expected magnitude and phase frequency responses are determined utilizing the model. The VFD and TD are tested by injecting a sequence of sine wave signals with different, predetermined frequencies from an external controller to the VFD as TD speed setpoint inputs on top of a constant base speed, and logging the test data. Magnitude and phase delay for the different frequency sine inputs to the VFD-TD loop are determined based on the logged data. Health of the VFD-TD system is assessed by comparing the determined magnitude and phase responses with the expected magnitude and phase responses. ## Claims ### Claim 1 A method comprising: determining expected magnitude and phase frequency responses of a top drive (TD) driven by a variable-frequency drive (VFD), wherein the VFD and the TD are part of a VFD-TD system of a well drilling system, and wherein determining the expected magnitude and phase frequency responses utilizes a model of a control loop for the VFD and the TD; generating test data by injecting a sequence of sine wave signals with different, predetermined frequencies to the VFD as TD speed setpoint inputs on top of a constant base speed; determining magnitude and phase delay for the different frequency sine inputs to the VFD-TD control loop based on the test data; and assessing health of the VFD-TD system by comparing the determined magnitude and phase responses with the expected magnitude and phase responses. ### Claim 2 (depends on 1) The method of claim 1 wherein the model utilizes parameters involving control gains of an automatic speed regulator (ASR) associated with the VFD-TD combination, a delay time constant derived from a time constant of a low-pass filter delay time constant, and a measured inertia of the TD. ### Claim 3 (depends on 1) The method of claim 1 wherein the control loop is modeled as comprising a proportional-integral (PI) controller and filter of the VFD, the TD inertia, an integrator, and a comparator that compares a speed setpoint with the output of the integrator, and wherein the integrator output is the actual speed of the VFD or TD. ### Claim 4 (depends on 1) The method of claim 1 wherein generating the model comprises utilizing transfer functions corresponding to the PI controller, the filter, the TD inertia, and the integrator. ### Claim 5 (depends on 1) The method of claim 1 wherein: a time period of the signals at each frequency is the same; and amplitude of the signals constantly ranges from about five revolutions per minute (rpm) to about twenty rpm at the TD. ### Claim 6 (depends on 1) The method of claim 1 wherein the testing includes high speed logging at a sampling rate of at least 200 Hz. ### Claim 7 (depends on 1) The method of claim 1 wherein determining the magnitude comprises: finding maximum and minimum values over the time period of the input signals; and determining averages of the maximum and minimum values. ### Claim 8 (depends on 1) The method of claim 1 wherein determining the phase delay comprises using discrete-time data sequences with delay estimate algorithms. ### Claim 9 (depends on 1) The method of claim 1 wherein assessing the VFD-TD system health comprises assessing whether the determined magnitude and phase responses are within a predetermined range of the expected magnitude and phase responses to determine if the determined magnitude and phase responses satisfy predetermined health-checking criteria. ### Claim 10 (depends on 1) The method of claim 1 further comprising assessing delay times between the external controller inputs and outputs using the test data. ### Claim 11 (depends on 10) The method of claim 10 further comprising assessing delay times between the VFD inputs and outputs using the test data. ### Claim 12 (depends on 1) The method of claim 1 further comprising generating a diagnosis report comprising: the assessed health; and general rig and/or TD information, including one or more of rig number, operator name, and the type, model, rated power, rated speed, and/or rated torque of the TD. ### Claim 13 (depends on 1) The method of claim 1 further comprising generating a diagnosis report comprising: the assessed health; and VFD and/or other device control parameters, including one or more of proportional and integral control gains of an automatic speed regulator (ASR) associated with the VFD-TD combination, TD inertia, and one or more filter time constants. ### Claim 14 (depends on 1) The method of claim 1 further comprising generating a diagnosis report comprising: the assessed health; and one or more predetermined and/or user-input health-checking criteria. ### Claim 15 (depends on 1) The method of claim 1 further comprising generating a diagnosis report comprising: the assessed health; and overall and/or test-specific pass/fail indications. ### Claim 16 A processing system comprising: a processor comprising a local memory; a main memory in communication with the processor; an input device in communication with the processor via an interface circuit; and an output device in communication with the processor via the interface circuit; wherein the processor is operable to execute coded instructions stored in the memory device and/or the local memory to: communicate with a variable-frequency drive (VFD) via the interface circuit, wherein the VFD is operable to drive a top drive (TD), and wherein the VFD and the TD are part of a VFD-TD system of a well drilling system; and in response to human-initiation via the input device, automatically: determine expected magnitude and phase frequency responses utilizing a model of a control loop for the VFD and the TD; generate test data by injecting a sequence of sine wave signals with different, predetermined frequencies to the VFD as TD speed setpoint inputs on top of a constant base speed; determine magnitude and phase delay for the different frequency sine inputs to the VFD-TD control loop based on the test data; and output to the output device an indication of health of the VFD-TD system, wherein the health indication is based on a comparison of the determined magnitude and phase responses with the expected magnitude and phase responses. ### Claim 17 (depends on 16) The processing system of claim 16 wherein the human-initiation via the input device comprises neither information utilized to generate the model nor information utilized by the model. ### Claim 18 (depends on 16) The processing system of claim 16 wherein the human-initiation via the input device comprises a single interaction by the human with the input device. ### Claim 19 A method comprising: entering a single input to an input device of a processing system, thereby commencing operation of a processor of the processing system to execute coded instructions stored in memory of the processing system to: determine expected magnitude and phase frequency responses of a top drive (TD) driven by a variable-frequency drive (VFD), wherein the VFD and the TD are part of a VFD-TD system of a well drilling system, and wherein determining the expected magnitude and phase frequency responses utilizes a model of a control loop for the VFD and the TD; generate test data by injecting a sequence of sine wave signals with different, predetermined frequencies to the VFD as TD speed setpoint inputs on top of a constant base speed; determine magnitude and phase delay for the different frequency sine inputs to the VFD-TD control loop based on the test data; determine an indication of health of the VFD-TD system by comparing the determined and expected magnitude and phase responses; and output the health indication via an output device of the processing system. ### Claim 20 (depends on 19) The method of claim 19 wherein the health indication output comprises a diagnosis report comprising: general rig and/or TD information, including one or more of rig number, operator name, and the type, model, rated power, rated speed, and/or rated torque of the TD; VFD and/or other device control parameters, including one or more of proportional and integral control gains of an automatic speed regulator (ASR) associated with the VFD-TD combination, TD inertia, and one or more filter time constants; one or more predetermined and/or user-input health-checking criteria; overall and/or test-specific pass/fail indications; and reasons for the pass/fail indications.