High Surge Impedance Loading Research Articles

The sensitivity analysis using adjoint method in numerical modeling of electric potential distribution of the transmission lines

AbstractThis paper proposes a new methodology for sensitivity analysis evaluation, fast and with high precision of the electric potential distribution near the transmission lines (TL's). The TL is modeled by the finite element method and the sensitivity of the cable positions is obtained using the adjoint method. The sensitivity of the objective function during the optimization process by using methods based on gradient information is obtained by using the adjoint method. The exact sensitivity obtained by the adjoint method concerning the numeric model of the TL's results in new geometries of the bundles conductors with high surge impedance loading. These geometries are not possible to get using analytic models. The sensitivities of a large number of conductors by phase are obtained with high precision and very low computational cost using adjoint sensitivities, which are independent of the number of design variables. The central finite difference method is used to calculate the sensitivities and to validate the adjoint method. With this methodology, the FEM model of the TL can be used during the optimization process without compromising the required computational processing time.

Fast Sensitivity Analysis of Electric Potential Distribution of Transmission Lines by Using Adjoint Method

In this article, a new methodology for sensitivity analysis evaluation of electric potential distribution near transmission lines (TLs) is proposed. The potential is modeled by the finite element method, and the sensitivity related to cable positions is obtained using the adjoint method, and thus the objective function’s sensitivity is adopted during the optimization process using a multiple cuts’ ellipsoid method to get new geometries with high surge impedance loading (SIL). The sensitivities of a large number of conductors by phase are obtained with high precision and very low computational cost, using adjoint sensitivities, which are not dependent on the number of design variables. The approximation using central finite differences (CFDs) to calculate the sensitivity is used for comparisons and validation. Therefore, with this methodology, the finite element method (FEM) model of TLs can be used during the optimization process without compromising the required computational processing time.

Methodology for Minimizing Electric Field at Ground Level from Transmission Lines Using Sensitivity Analysis

In this paper, a new methodology is applied to optimize the geometry of conductors of overhead transmission lines (TL) with high precision and low computational cost. This methodology is based on the sensitivity analysis of the electrical charge of the transmission lines using the adjoint method. This information is used with the gradient method and the golden section algorithm to minimize the electric field at the ground level of three-phase TL with two cables per phase. The approximation using central finite differences to obtain sensitivity is adopted for validation and comparisons. The TL's with high surge impedance loading is obtained after the optimization process.

Calculation of Transmission Lines and Electrical Equipment of 150kV Main Guluk- Guluk Madura Island East Java, Indonesia

Guluk-Guluk is supplied by a 20 kV system from the Pamekasan GI and Sumenep GI, resulting in a voltage drop of 5 kV. The fall in the voltage on the load side cannot be overcome through the regulation of transformer tapping or the use of bank capacitors, so the possible way is to build a new GI. The construction of GI Guluk-Guluk requires a new transmission line. A good electric power transmission has a low voltage drop, high efficiency and high surge impedance loading (SIL) values. Efforts to improve the voltage by changing the tapping in the power transformer located at the nearest substation only produce a voltage of 166.07 kV. The provision of bank capacitors in Guluk-Guluk produces a voltage of 17,542 kV. The construction of GI Guluk-Guluk requires a new transmission line that connects Pamekasan to Guluk-Guluk, Sampang to Guluk-Guluk and Guluk-Guluk to Sumenep. The construction of a 150 kV network line requires calculations to determine network configurations, conductors, isolators, tower types, and electrical equipment supporting 150 kV transmission systems such as current transformers, voltage transformers, power breakers, and arresters. In this final project, simulation is done with the help of ETAP 12.6 software. The results of calculations and simulations of the transmission line toward Guluk-Guluk give a voltage drop of 4.89 kV, with an efficiency level of 96.74% and a SIL value of 41.225 MW. so these results are sufficient to be used as a reference for GI development in Guluk-Guluk.

Statistical Switching Overvoltage Studies of Optimized Unconventional High Surge Impedance Loading Lines via Numerical Laplace Transform

The development of a revolutionary design for transmission lines was recently introduced by shifting phase configurations and sub-conductors into “unconventional” arrangements that were geometrically optimized to maximize natural power. The objective of this paper is to study the electromagnetic transients that result from the simultaneous and sequential line energization and re-energization of the previously developed unconventional high surge impedance loading (HSIL) lines. Statistical switching overvoltage (SSOV) studies are performed using a frequency domain method based on the inverse numerical Laplace transform. Compared to a conventional line, all unconventional HSIL line designs studied in this paper lead to very similar surges for long line lengths (400 km) and similar values for short line lengths (100 km), indicating additional advantages of these lines. The use of a frequency domain method for SSOV studies offers enhanced accuracy, simulation flexibility, and substantially lower computational burden compared with traditional time-domain methods.

A New Strategy for Optimizing HSIL Transmission Lines

This paper presents an efficient procedure for optimizing the electric field at ground level of high surge impedance loading transmission lines. Such lines have the capacity to achieve higher power transmission rates than the conventional ones. The ellipsoidal method is applied in order to maximize the transmitted power and minimize the electric field at ground level through the variation of the conductor’s positions in the tower, given its physical and electrical constraints. By means of an efficient new approach to handle the conductors, the optimization gives birth to compact line designs combined with conventional bundles of conductors. Furthermore, it is shown that the proposed strategy can increase the transmitted power, reduce the electric field at ground level, and shorten the running time of the optimization algorithm.

Bulk FDTD Simulation of Distributed Corona Effects and Overvoltage Profiles for HSIL Transmission Line Design

Power system load growth and transmission corridor constraints are driving industry activity in the area of high surge impedance loading (HSIL). Examples include compact structure design and uprating existing transmission lines. Recent research relating electric field uniformity to transmission line capacity and critical flashover voltage underscored the need for better overvoltage data to quantify insulation margins for HSIL design. To that end, this work extends the finite difference time domain (FDTD) method with distributed corona losses to transmission lines with bundled conductors. The model was adapted for practical use in high-volume statistical transient simulation and applied to an example 500 kV line. Transients included line energization and trapped charge reclosing. Overvoltage profiles and statistical distributions were generated from 9500 simulations obtained by random breaker close timing and variation in line length and altitude. Distributed corona losses reduced 98th percentile line-to-ground switching overvoltages by 4%–14% of nominal. The estimated line-to-ground switching surge flashover probability was 54%–80% lower with corona loss. Corona had less impact on line-to-line overvoltages, but the effects were still notable. Results highlight the importance of considering detailed overvoltage profiles and accounting for corona loss attenuation when seeking to carefully quantify insulation design margins.

High Surge Impedance Loading (HSIL) Lines: A Review Identifying Opportunities, Challenges, and Future Research Needs

Making old new again: next generation of self-reactive power compensation high surge impedance loading (HSIL) lines engaging transmission expansion planning (TEP) can be a game-changing technological innovation to overtake traditional overhead line designs. The paper summarizes, reviews, and presents motivations, opportunities, and challenges for developing HSIL designs. This study will provide a useful framework and point of reference for the future development of HSIL lines. It also proposes, for the first time, integration of TEP and line design to optimize the power transfer capability of a power system.

The surge impedance loading optimization by an adaptive Deep Cut Ellipsoidal algorithm

This paper presents a computational tool intended to achieves optimal configurations of conductors with capacity of transmission of energy improved. This arrangement is obtained by calculate and minimize of electric fields at ground level of High Surge Impedance Loading transmission lines. This type of transmission line has higher power transmission rates by utilizing optimized configuration for the conductors. In the present work, an enhanced Deep Cut Ellipsoidal Method is applied to find a new optimized configuration for the phase conductors. The Surge Impedance Loading of the suggested configuration is analyzed. The new proposed configuration results in reduced profiles of electric fields and higher power transmission capacity.

An Adaptive Deep-Cut Ellipsoidal Algorithm Applied to the Optimization of Transmission Lines

This paper presents a computational tool intended to calculate and minimize the electric fields at ground level of high surge impedance loading transmission lines (TLs). This type of TL achieves higher power transmission rates utilizing optimized configuration for the phase conductors. This method is advantageous over other actions taken by the utility company, such as increasing the maximum operation temperature of the line, increasing the size of the conductors, or the utilization of multiple conductors per phase. In this paper, an enhanced deep-cut ellipsoidal method is applied to find a new optimized configuration for the phase conductors. The new proposed configuration results in reduced profiles of electric fields. Two different TLs are analyzed and optimized.

Fluxo de carga em sistemas que apresentam linhas de potência natural elevada (LPNE)

Este trabalho apresenta um procedimento preciso para o cálculo de fluxo de carga em sistemas elétricos de potência nos quais estão presentes linhas de potência natural elevada (LPNE). A metodologia consiste no uso do fluxo de potência trifásico em coordenadas de fase para solução de um subsistema onde os efeitos dos desequilíbrios causados pelas linhas LPNEs são mais acentuados. Para o restante do sistema adota-se o tradicional fluxo de carga de seqüência positiva. O modelo proposto foi validado usando-se o sistema de 57 barras do IEEE.

Circuit-breaker requirements for alternative configurations of a 500 kV transmission system

This paper describes a study made to assess the electrical stresses imposed on line circuit breakers of a new 500 kV AC expansion of the FURNAS transmission system, to be possibly installed in the Brazilian central region. The study has considered three configurations of the transmission lines, two of which assume the use of compact towers. In one of these two cases, the lines would have high surge-impedance loading. Digital simulations have been made with the aid of the Alternative Transients Program (ATP) to calculate the switching transients appearing as a result of line energization and reclosing, clearing of terminal and short-line faults, no-load line opening in normal and faulted conditions and out-of phase switching. Four alternatives have been considered for the limitation of overvoltages on closing, assuming either the sole use of surge arresters on each line end or the use, in addition to the arresters, of pre-insertion resistors, synchronizers or time relays to provide a staggered closing of the breaker poles. The stresses obtained were compared with those applied by the standard IEC tests or with the maximum admissible levels usually considered by the utility for its transmission branches at the planning stage.

A proposed design for the new Furnas 500 kV transmission lines-the High Surge Impedance Loading Line

This paper describes the studies related with the concept of a new compact tower called High Surge Impedance Loading Line (HSILL) as an alternative for the new 500 kV, AC expansion of the Furnas transmission system. Those studies considered specific digital programs for evaluation of the best optimized bundle conductors configuration, phase-to-phase insulation electrical strength laboratory tests and overvoltage studies, radio-interference and corona losses measurements.