In deep drilling applications,such as those for geothermal energy,there are many challenges,such as those related to efficient operation of the drilling fluid(mud)pumping system.Legacy drilling rigs often use paired,p...In deep drilling applications,such as those for geothermal energy,there are many challenges,such as those related to efficient operation of the drilling fluid(mud)pumping system.Legacy drilling rigs often use paired,parallel-connected independent-excitation direct-current(DC)motors for mud pumps,that are supplied by a single power converter.This configuration results in electrical power imbalance,thus reducing its efficiency.This paper investigates this power imbalance issue in such legacy DC mud pump drive systems and offers an innovative solution in the form of a closed-loop control system for electrical load balancing.The paper first analyzes the drilling fluid circulation and electrical drive layout to develop an analytical model that can be used for electrical load balancing and related energy efficiency improvements.Based on this analysis,a feedback control system(so-called“current mirror”control system)is designed to balance the electrical load(i.e.,armature currents)of parallel-connected DC machines by adjusting the excitation current of one of the DC machines,thus mitigating the power imbalance of the electrical drive.Theproposed control systemeffectiveness has been validated,first through simulations,followed by experimental testing on a deep drilling rig during commissioning and field tests.The results demonstrate the practical viability of the proposed“current mirror”control system that can effectively and rather quickly equalize the armature currents of both DC machines in a parallel-connected electrical drive,and thus balance both the electrical and mechanical load of individual DC machines under realistic operating conditions of the mud pump electrical drive.展开更多
All-solid-state lithium-based batteries represent a critical evolution in energy storage,offering enhanced safety,higher energy density,and superior fast-charging capabilities.However,the integration of solid-state el...All-solid-state lithium-based batteries represent a critical evolution in energy storage,offering enhanced safety,higher energy density,and superior fast-charging capabilities.However,the integration of solid-state electrolytes introduces complex mechanical interactions at the electrode-electrolyte interface that significantly impact performance and longevity.This study introduces a cyclic plastic hardening model for ceramic electrolytes,moving beyond traditional brittle or linear-elastic assumptions.It presents a Finite Element Method(FEM)analysis of a positive electrode representative volume element(RVE),consisting of spherical Nickel-Manganese-Cobalt(NMC811)active material particles embedded in an Li_(7)La_(3)Zr_(2)O_(12)(LLZO)solid-state electrolyte matrix,with Gaussian-distribution of particle sizes aimed to capture the stochastic heterogeneity of electrode microstructures.The simulation results illustrate the volumetric expansion and contraction of active material during lithiation and de-lithiation(electrochemical loading)cycles using a thermal expansion analogy.Due to the scarcity of cyclic plasticity data for ceramic electrolytes,the plastic hardening behavior of LLZO is approximated using a proxy material model(SiMo5 steel at 700°C)to qualitatively capture strain hardening effects.The study analyzes stress distribution,volumetric deformation,and contact evolution over five charge-discharge cycles under a uniform assembly external pressure of 10 MPa.Results indicate progressive strain hardening in the solid electrolyte,characterized by increasing tensile stresses and stabilizing volumetric deformation.Furthermore,the analysis reveals cyclic contact loss during de-lithiation,which poses risks for increased interfacial resistance.These findings provide theoretical insights into the mechanical degradation mechanisms of ASSBs,emphasizing the key role of stack pressure and material hardening in their long-term stability.展开更多
文摘In deep drilling applications,such as those for geothermal energy,there are many challenges,such as those related to efficient operation of the drilling fluid(mud)pumping system.Legacy drilling rigs often use paired,parallel-connected independent-excitation direct-current(DC)motors for mud pumps,that are supplied by a single power converter.This configuration results in electrical power imbalance,thus reducing its efficiency.This paper investigates this power imbalance issue in such legacy DC mud pump drive systems and offers an innovative solution in the form of a closed-loop control system for electrical load balancing.The paper first analyzes the drilling fluid circulation and electrical drive layout to develop an analytical model that can be used for electrical load balancing and related energy efficiency improvements.Based on this analysis,a feedback control system(so-called“current mirror”control system)is designed to balance the electrical load(i.e.,armature currents)of parallel-connected DC machines by adjusting the excitation current of one of the DC machines,thus mitigating the power imbalance of the electrical drive.Theproposed control systemeffectiveness has been validated,first through simulations,followed by experimental testing on a deep drilling rig during commissioning and field tests.The results demonstrate the practical viability of the proposed“current mirror”control system that can effectively and rather quickly equalize the armature currents of both DC machines in a parallel-connected electrical drive,and thus balance both the electrical and mechanical load of individual DC machines under realistic operating conditions of the mud pump electrical drive.
基金supported by the European Regional Development Fund under grant agreement PK.1.1.10.0007(DATACROSS).
文摘All-solid-state lithium-based batteries represent a critical evolution in energy storage,offering enhanced safety,higher energy density,and superior fast-charging capabilities.However,the integration of solid-state electrolytes introduces complex mechanical interactions at the electrode-electrolyte interface that significantly impact performance and longevity.This study introduces a cyclic plastic hardening model for ceramic electrolytes,moving beyond traditional brittle or linear-elastic assumptions.It presents a Finite Element Method(FEM)analysis of a positive electrode representative volume element(RVE),consisting of spherical Nickel-Manganese-Cobalt(NMC811)active material particles embedded in an Li_(7)La_(3)Zr_(2)O_(12)(LLZO)solid-state electrolyte matrix,with Gaussian-distribution of particle sizes aimed to capture the stochastic heterogeneity of electrode microstructures.The simulation results illustrate the volumetric expansion and contraction of active material during lithiation and de-lithiation(electrochemical loading)cycles using a thermal expansion analogy.Due to the scarcity of cyclic plasticity data for ceramic electrolytes,the plastic hardening behavior of LLZO is approximated using a proxy material model(SiMo5 steel at 700°C)to qualitatively capture strain hardening effects.The study analyzes stress distribution,volumetric deformation,and contact evolution over five charge-discharge cycles under a uniform assembly external pressure of 10 MPa.Results indicate progressive strain hardening in the solid electrolyte,characterized by increasing tensile stresses and stabilizing volumetric deformation.Furthermore,the analysis reveals cyclic contact loss during de-lithiation,which poses risks for increased interfacial resistance.These findings provide theoretical insights into the mechanical degradation mechanisms of ASSBs,emphasizing the key role of stack pressure and material hardening in their long-term stability.
