We employ the Galerkin method to prove the global existence of weak solutions to a phase-field model which is suitable to describe a sort of interface motion driven by configurational forces.The higher-order derivativ...We employ the Galerkin method to prove the global existence of weak solutions to a phase-field model which is suitable to describe a sort of interface motion driven by configurational forces.The higher-order derivative of unknown S exists in the sense of local weak derivatives since it may be not summable over the original open domain.The existence proof is valid in the one-dimensional case.展开更多
Low voltage three-phase four-wire AC distribution grids may experience high neutral current,mainly caused by asymmetrical distribution of single-phase loads in three phases.High neutral current will not only increase ...Low voltage three-phase four-wire AC distribution grids may experience high neutral current,mainly caused by asymmetrical distribution of single-phase loads in three phases.High neutral current will not only increase line losses but also result in neutral potential variations.For the LV AC distribution grid established by a grid-forming inverter(e.g.,uninterruptible power supply and solid-state-transformer),it also suffers from the same neutral current issues.Therefore,this paper comparatively studies several neutral current control approaches and their impacts on grid voltage balance,which is required by grid code.Then,this paper proposes an optimal neutral current control approach,which can obtain maximum neutral current suppression with less impact on grid voltage balance.The correctness of the theoretical analysis is validated through both simulation and experimental results.展开更多
基金supported by the Science and Technology Commission of Shanghai Municipality of China(No.20JC1413600)。
文摘We employ the Galerkin method to prove the global existence of weak solutions to a phase-field model which is suitable to describe a sort of interface motion driven by configurational forces.The higher-order derivative of unknown S exists in the sense of local weak derivatives since it may be not summable over the original open domain.The existence proof is valid in the one-dimensional case.
基金the National Natural Science Foundation of China(NSFC)under Grant 51767017National Science and Technology Major Project of Gansu Province under Grant 19ZD2GA003.
文摘Low voltage three-phase four-wire AC distribution grids may experience high neutral current,mainly caused by asymmetrical distribution of single-phase loads in three phases.High neutral current will not only increase line losses but also result in neutral potential variations.For the LV AC distribution grid established by a grid-forming inverter(e.g.,uninterruptible power supply and solid-state-transformer),it also suffers from the same neutral current issues.Therefore,this paper comparatively studies several neutral current control approaches and their impacts on grid voltage balance,which is required by grid code.Then,this paper proposes an optimal neutral current control approach,which can obtain maximum neutral current suppression with less impact on grid voltage balance.The correctness of the theoretical analysis is validated through both simulation and experimental results.
