A Generic Approach for HVDC Cable Accessories Modelling

Frobin, Saskia Josefine; Niedik, Christoph Felix; Freye, Claudius; Jenau, Frank; Haring, Dominik; Schroder, G.H.

doi:10.1109/icd.2018.8514703

Cited by 8 publications

(13 citation statements)

References 10 publications

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“…3. Simulation of cable joints with geometric and nonlinear field grading techniques Within the thermal simulations, the conductor temperature is set to T i = 70°C and the dissipated heat is modeled with a convective heat current density jq th j = a th (T À T 1 ), defined with a heat transfer coefficient a th = 5 W/(Km 2 ) and an environment temperature of T 1 = 20°C (Frobin et al, 2018). The constant thermal conductivity values of the materials are l XLPE = 0.38 W/(Km), l EPDM = 0.3 W/(km), l FGM = 0.5 W/(km) and l Stress-cone = 0.3 W/ (km).…”

Section: Hvdc Cable Jointsmentioning

confidence: 99%

Electric field simulations of field grading techniques in HVDC cable joints

Jörgens

Clemens

2022

COMPEL

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Purpose In high voltage direct current cable systems, cable joints are known as the least reliable components due to the use of multiple dielectrics. Resulting from the electric field and temperature depending conductivity of the different dielectrics, field enhancement at critical areas, e.g. triple points, may result in accelerated aging and the failure of the component. To reduce the stress, different field grading techniques are applied. The purpose of this study is to investigate different grading techniques for cable joints. Different shapes of the electrode and a varying nonlinear conductivity of field grading materials (FGM) are used for the simulation of the electric field. Design/methodology/approach Coupled electro-thermal field simulations are applied for different joint geometries, to obtain the stationary electric field. Electric field simulations in cable joint using geometric and nonlinear field grading techniques are shown. Findings Using the geometric field grading, the shape of the stress cone determines the field values in critical areas (triple points). High stress reduction is obtained for a certain curvature of the stress cone. For the nonlinear stress control, materials with a higher conductivity in comparison to the cable and the joint material are used. A field reduction is obtained by increasing the total conductivity. On the other hand, this is also increasing the insulation losses within the total FGM. More applicable is the decrease of the switching field or the increase of nonlinearity, which is only locally increase the conductivity and the insulation losses. Furthermore, simulations results show that an approximately constant field reduction is obtained, if the nonlinearity is above a certain threshold. Research limitations/implications This study is restricted to a field dependency of FGM only. For impulse voltages, high temperature and electric conductivity values my result in a thermal runaway. Furthermore, only direct current field grading techniques are studied. Originality/value The field grading of cable joints, using geometric and nonlinear techniques, is analyzed. A comparison between the electric field, by varying the curvature of the ground stress cone or the FGM conductivity constants in a complex joint geometry is novel. With its effect on the electric fields, general requirements for the geometry (geometric field grading) or the values of the FGM constants (nonlinear field grading) are defined to obtain a sufficient field grading.

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Section: Hvdc Cable Jointsmentioning

confidence: 99%

Electric field simulations of field grading techniques in HVDC cable joints

Jörgens

Clemens

2022

COMPEL

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“…where α out is the heat transmission coefficient [65][66][67][68]. Using Figure 6, the maximum space charge density (Figure 6c) and thus, the maximum field inversion (Figure 6b) are obtained for a stationary temperature distribution, showing the maximum temperature gradient (Figure 6a).…”

Section: Transient and Stationary Electric Field Under Various Therma...mentioning

confidence: 99%

“…Thus, in several studies only the stationary temperature distribution is considered [11,14,25,26]. [11,30,65,66].…”

Section: Transient and Stationary Electric Field Under Various Therma...mentioning

confidence: 99%

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A Review about the Modeling and Simulation of Electro-Quasistatic Fields in HVDC Cable Systems

Jörgens

Clemens

2020

Energies

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In comparison to high-voltage alternating current (HVAC) cable systems, high-voltage direct current (HVDC) systems have several advantages, e.g., the transmitted power or long-distance transmission. The insulating materials feature a non-linear dependency on the electric field and the temperature. Applying a constant voltage, space charges accumulate in the insulation and yield a slowly time-varying electric field. As a complement to measurements, numerical simulations are used to obtain the electric field distribution inside the insulation. The simulation results can be used to design HVDC cable components such that possible failure can be avoided. This work is a review about the simulation of the time-varying electric field in HVDC cable components, using conductivity-based cable models. The effective mechanisms and descriptions of charge movement result in different conductivity models. The corresponding simulation results of the models are compared against measurements and analytic approximations. Different numerical techniques show variations of the accuracy and the computation time that are compared. Coupled electro-thermal field simulations are applied to consider the environment and its effect on the resulting electric field distribution. A special case of an electro-quasistatic field describes the drying process of soil, resulting from the temperature and electric field. The effect of electro-osmosis at HVDC ground electrodes is considered within this model.

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“…Different studies were dedicated to HVDC cables and their nonlinear behavior [15][16][17][18][19][20]. Several authors outlined the modeling and simulation of HV cable joints [21,22]. Only a few systematic investigations have been carried out so far on the nonlinear field-controlling behavior of HVDC cable joints [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Towards Electrothermal Optimization of a HVDC Cable Joint Based on Field Simulation

et al. 2021

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Extruded high-voltage direct current cable systems transmit electric power over long distances. Numerical field simulation can provide access to the internal electrothermal behavior of cable joints, which interconnect cable sections. However, coupled nonlinear electrothermal field simulations are still a challenge. In this work, a robust numerical solution approach is implemented and validated. This approach allows for efficient parameter studies of resistively graded high-voltage direct current cable joint designs. It is assessed how the dielectric stress distribution between the conductor connection and the grounded cable sheath is influenced by nonlinear field and temperature dependent electric conductivity of the field grading material. Optimal field grading material parameters, which fulfill the field grading and power loss requirements, are suggested based on the simulation studies.

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A Generic Approach for HVDC Cable Accessories Modelling

Cited by 8 publications

References 10 publications

Electric field simulations of field grading techniques in HVDC cable joints

Electric field simulations of field grading techniques in HVDC cable joints

A Review about the Modeling and Simulation of Electro-Quasistatic Fields in HVDC Cable Systems

Towards Electrothermal Optimization of a HVDC Cable Joint Based on Field Simulation

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