Novel evaluation methods of end-turn stress grading materials for converter-fed high voltage rotating machines

Umemoto, Takuya; Tsurimoto, Takao; Kisakibaru, Tomohito; Sakurai, Takayuki; Tsuda, Toshihiro; Karasawa, Kazunari

doi:10.1109/ceidp.2016.7785583

Cited by 9 publications

(5 citation statements)

References 7 publications

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“…Usually, the main insulation is provided with outer corona protection applied by multilayer semiconducting paints or wrapping tapes [ 28 ]. Carbon-based semiconductive tapes and SiC-based nonlinear grading tapes have been widely used to control the field where the stator bar exits from the slot in form-wound large rotating machines [ 41 ]. The conductivity of the stress-grading tape depends on the electric field and is high at the end of the semiconductive armor tape, where the electric field is the highest and gradually decreases along the stress-grading tape.…”

Section: Electric-field Grading In Hv Applicationsmentioning

confidence: 99%

Section: Current Applications Of Nonlinear Polymer Composites In Hv Engineeringmentioning

confidence: 99%

“…Therefore, it makes the electric field at the end of the CAT more uniform. Umemoto et al [41] also reported the use of a nonlinear grading tape to control the field in a stator bar from large rotating machines. Donzel and Schuderer [33] reported the application of nonlinear resistive electric field control for high-power modules with insulated-gate bipolar transistors.…”

Section: Current Applications Of Nonlinear Polymer Composites In Hv Engineeringmentioning

confidence: 99%

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Nonlinear Electrical Conduction in Polymer Composites for Field Grading in High-Voltage Applications: A Review

et al. 2021

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Applications of polymeric materials in electrical engineering increasingly require improvements in operating voltages, performance, reliability, and size reduction. However, the resulting increase on the electric field in electrical systems can prevent achieving these goals. Polymer composites, functionalized with conductive or semiconductive particles, can allow us to reduce the electric field, thus grading the field within the system. In this paper, a comprehensive review of field-grading materials, their properties, and recent developments and applications is provided to realize high-performance high-voltage engineering applications.

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Section: Electric-field Grading In Hv Applicationsmentioning

confidence: 99%

Section: Current Applications Of Nonlinear Polymer Composites In Hv Engineeringmentioning

confidence: 99%

Section: Current Applications Of Nonlinear Polymer Composites In Hv Engineeringmentioning

confidence: 99%

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Nonlinear Electrical Conduction in Polymer Composites for Field Grading in High-Voltage Applications: A Review

et al. 2021

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“…FEM has become one of the most commonly used techniques for modeling stress-grading systems [37][38][39]. With FEM, the geometry can be considered including most of the details that influence the electric field distribution.…”

Section: Modeling Of Stress-grading Systems From Rotating Machinesmentioning

confidence: 99%

Modeling and Simulation of Rotating Machine Windings Fed by High-Power Frequency Converters for Insulation Design

Cortés¹,

Gómez²,

KhalilHussain³

2018

Simulation and Modelling of Electrical Insulation Weaknesses in Electrical Equipment

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Modern power systems include a considerable amount of power electronic converters related to the introduction of renewable energy sources, high-voltage direct current (HVDC) systems, adjustable speed drives, and so on. These components introduce repetitive pulses generated by the commutation of semiconductor switches, resulting in overvoltages with very steep fronts and high dielectric stresses. This phenomenon is one of the main causes of accelerated insulation aging of motors in power electronic-based systems. This chapter presents state-of-the-art computational tools for the analysis of motor windings excited by fast-front pulses related to the use of frequency converters based on pulsewidth modulation (PWM). These tools can be applied for the accurate prediction of overvoltages and dielectric stresses required to propose insulation design improvements. In the case of the stress-grading system used in medium-voltage (MV) motors, transient finite-element method (FEM) is used to study the effect of fast pulses. It is shown how, by controlling the material properties and the design of the stress-grading systems, solutions to reduce the adverse effects of fast pulses from PWM-type inverters can be proposed.

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“…In [6], [12]- [17], the nonlinear conduction properties of the SGT were investigated for the stress grading of the overhang region; however, the VPI procedure was not addressed. In [18]- [20], the VPI procedure was considered in measuring the properties of the SGT, but the effect of heat shrinkage tape (HST) or the mica insulation layer was not considered. As with the VPI, the shrink tape and mica layers are also factors that must be considered in order to predict the actual electric field distribution.…”

Section: Introductionmentioning

confidence: 99%

Stress Grading Performance Analysis of Stator Coil Considering the Manufacturing Method and the Insulation Design

Kim

2022

IEEE Access

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In rotating machines, the approach of applying nonlinear conductive stress grading tape (SGT) has been applied to reduce the electric field stress in the coil's overhang region. To characterize and verify the electric field grading effect of SGT in electric machines, electric field analysis using the nonlinear conductivity of SGT as a boundary condition must be considered. However, previous studies have shown limitations in the characterization and application of SGT materials in insulation system design for various reasons, such as lack of conductivity measurement standards for nonlinear materials or not considering possible changes in material properties during the manufacturing procedure. In this study, the nonlinear conductivity of SGT was measured by considering the rotating machine's manufacturing procedure. A finite element method (FEM) electric field analysis was performed using the measured nonlinear conductivity. Based on the improved conductivity measurement method of SGT and FEM analysis, the effects of changing several insulation design parameters in the field grading performance were studied on a 13.8 kV stator coil. Moreover, the effect of preheating on the SGT conductivity was also examined. Based on analysis results, we realized the possibility of more precise insulation design of the stator coil. Our findings supplement the insufficient insulation design guide on the SGT part and contribute to establishing a systematic approach for insulation design. Furthermore, the proposed methods enable design optimization and detection of the cause of insulation failure.

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Novel evaluation methods of end-turn stress grading materials for converter-fed high voltage rotating machines

Cited by 9 publications

References 7 publications

Nonlinear Electrical Conduction in Polymer Composites for Field Grading in High-Voltage Applications: A Review

Nonlinear Electrical Conduction in Polymer Composites for Field Grading in High-Voltage Applications: A Review

Modeling and Simulation of Rotating Machine Windings Fed by High-Power Frequency Converters for Insulation Design

Stress Grading Performance Analysis of Stator Coil Considering the Manufacturing Method and the Insulation Design

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