Tower Surge Response Research Articles

Stability analysis of floating wind turbine structure with turned mass damper-nonlinear energy sink

The conventional tuned mass damper (TMD) has the defect of a narrow tuning band in the stability control of a floating wind turbine (FWT). In this paper, a hybrid vibration reduction method of tuned mass damper-nonlinear energy sink (TMD-NES) is proposed, which makes full use of the broadband advantage of NES and can effectively avoid its initial energy sensitivity disadvantage. A FWT dynamics model with TMD-NES was established, the complex variable average method was used to solve the dynamic response of the system, and the Runge–Kutta method is used to prove the reliability of the analytical method. The bifurcation characteristics of NES and the vibration suppression effect of TMD-NES are analyzed and discussed. The results show that the proposed method reduces the peak energy of the tower surge response by 95.3%, broadens the frequency band of vibration reduction, reduces the sensitivity to the initial energy, and improves the robustness of the system.

Lightning surge response of a double-circuit transmission tower with incoming lines to a substation through FDTD simulation

A transmission tower model that can reproduce the lightning surge response is important for analyzing the lightning surge. In developing such tower model, however, studies have been conducted using a stand-alone tower or a condition where the tower and transmission lines are orthogonally crossed. This could be attributable to the difficulty in handling a complex layout in conventional experiments and theoretical studies. The present paper verifies the accuracy of the FDTD analysis, based on a comparison with the experimental results. Subsequently, it studies the influence of the layout and the inclined angle of the incoming lines to the substation on the surge response of the tower under near-real facility conditions via electromagnetic field analysis using the FDTD method. As a result, the voltage of the insulator strings peaked with a zero-degree incoming angle and it declined with increasing angle, namely by about 20% when the inclined angle was 37.5 degrees. Finally, the current waveform was analyzed in addition to the voltage characteristics and the generation mechanism of the line voltage was explained.

Lightning surge response of a double-circuit transmission tower with incoming lines to a substation through FDTD simulation

A transmission tower model that can reproduce the lightning surge response is important for analyzing the lightning surge. In developing such tower model, however, studies have been conducted using a stand-alone tower or a condition where the tower and transmission lines are orthogonally crossed. This could be attributable to the difficulty in handling a complex layout in conventional experiments and theoretical studies. The present paper verifies the accuracy of the FDTD analysis, based on a comparison with the experimental results. Subsequently, it studies the influence of the layout and the inclined angle of the incoming lines to the substation on the surge response of the tower under near-real facility conditions via electromagnetic field analysis using the FDTD method. As a result, the voltage of the insulator strings peaked with a zero-degree incoming angle and it declined with increasing angle, namely by about 20% when the inclined angle was 37.5 degrees. Finally, the current waveform was analyzed in addition to the voltage characteristics and the generation mechanism of the line voltage was explained.

Application of a Frequency-Domain Partial Element Equivalent Circuit Method to Tower Surge Response Calculations

This paper presents tower surge response calculations on an actual transmission tower including ground wires and phase wires. A frequency-domain partial element equivalent circuit (PEEC) method is applied as a simulation tool. Insulator voltages calculated by the voltage difference of crossarms and phase wires are compared with experimental results collected from the literature. In addition, a transmission line (TL) model is adopted with the PEEC method to increase efficiency for transient surge calculation. The results calculated by the PEEC method with and without the TL model agree well with the experimental results not only for amplitudes but also for waveshapes.

Application of the partial element equivalent circuit method to tower surge response calculations

AbstractThis article presents calculations of tower surge responses and insulator voltages of an actual transmission tower including ground wires and phase wires. The partial element equivalent circuit (PEEC) method is applied as a simulation tool. Surge responses of the tower and insulator voltages calculated by the PEEC method are compared with electro magnetic transients program (EMTP) simulated results and experimental results collected from the literatures. The results calculated by the PEEC method agree well with the experimetal results, not only amplitudes but also waveshapes. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Experimental and Analytical Studies on Lightning Surge Response of 500-kV Transmission Tower

This paper presents experimental and analytical studies on the lightning surge response of a 500-kV transmission tower without overhead lines. A number of experimental studies on the lightning surge response of transmission towers have been carried out. However, in these studies, the influence of the current injection angle was ignored. In this paper, an experimental investigation is conducted to assess the influences of the angle and direction of current injection. It is clearly shown that the lightning surge response of the tower depends on the angle and direction of current injection. These experimental results are compared with results calculated using numerical electromagnetic (EM)-field analysis. These calculated results agree with the experimental results. This suggests that numerical EM-field analysis can be employed for evaluating the surge response of a tower. Based on this, the surge response of a tower under a vertical lightning stroke is estimated. It is shown that the surge response under vertical current injection is approximately 30% higher than that under horizontal current injection. It is also shown that the angle and direction of the return stroke are important factors in determining the lightning surge response of a transmission tower.

Investigations on Voltages and Currents in Lightning Protection Schemes Involving Single Tower

A reliable protection against natural lightning has become very essential for modern critical systems. For very vulnerable systems, the protection system is physically isolated from them. In such cases, towers taller than system being protected are generally employed. The maximum allowable bypass current and the so-called rise in potential during the strike decide the height and location of such towers. For tall towers, TM modes dominate at least during the rising portion of the current making the analysis very complicated. In view of this, for a better assessment of the potential at the top and the base currents, experimental investigation in the frequency domain is carried out on the electromagnetically scaled model of the actual tower. The possible reduction in the tower base currents with the connection of ground wires and the influence of neighboring structures on the tower surge response are also studied. Investigations are also carried out on an alternative design involving mast insulated from the supporting tower and a separate set of ground wires acting as down conductors. Some analysis on the electric withstand capabilities of the insulating support is also made. The findings of the present work are believed to be quite useful to lightning protection engineering.

Lightning surge analysis using nonuniform, single-phase line model

In the analysis of lightning surges, transmission towers are usually simulated by nonuniform lines, but overhead lines are assumed uniform. If the effect of line sags is considered, the variation of the overhead line parameters with respect to space should also be treated as nonuniform. Tower surge response is computed using nonuniform, single-phase line models for both transmission tower and ground wire. Using boundary conditions for these lines, total response of the system in s-domain is obtained. A fast inverse Laplace transform is used for the frequency-to-time domain conversion. The effect of line losses is included.

Numerical electromagnetic field analysis on lightning surge response of tower with shield wire

Lightning surge characteristics of a transmission line comprising a tower, a shield wire and phase conductors are studied with the help of NEC-2. A tower struck by a lightning stroke behaves as an antenna until a traveling wave makes several roundtrips in the tower. During this interval, the tower footing impedance appears to be higher than the footing resistance, and the coupling coefficient between a shield wire and a phase conductor is much lower than that in the TEM mode. These affect the estimation of insulator voltages of transmission towers subject to lightning currents having short rise times. On the basis of these findings, the parameters in the multistory tower model, which has been used widely in EMTP multi-conductor analyzes, are newly proposed.

Analytical and experimental study on surge response of transmission tower

This paper describes analytical and experimental studies on tower surge response, including effects of return stroke current. Such effects have been ignored in previous lightning surge analyzes of transmission towers. A new method for calculating transmission tower surge response including the effects of return stroke current is proposed. The proposed method is based on the electromagnetic field theory, and it clearly shows that the tower surge response depends on the direction and velocity of the return stroke current. The tower surge response calculated by the proposed method agrees well with the measured tower surge response obtained from scale model tests and field tests.

Numerical electromagnetic field analysis of tower surge response

Tower surge responses are computed by the numerical electromagnetic code. The code used in this paper is not the one based on the circuit theory such as the Electromagnetic Transients Program (EMTP), but the one that solves the electric field equations directly by the moment method. The accuracy of this method is shown to be satisfactory by comparison with experimental results that were carried out on an actual UHV tower as well as reduced-scale models. And then by using this method, the influences of tower elements such as slant elements, horizontal elements and crossarms on the tower surge characteristics are investigated. In addition, the surge impedance of a full-sized tower hit directly by a lightning stroke is discussed.

Numerical Electromagnetic Field Analysis of Tower Surge Response

Numerical Electromagnetic Field Analysis of Tower Surge Response

A simple approach to improve lightning performance of an uprated substation

This paper presents a simple method to minimize lightning surges entering an uprated or compact substation. A severe lightning stress is caused by a backflashover in close proximity to the substation. Feasibility of uprating is based on the surge arrester technology available at present. However, some aspects of line design offer opportunities in reducing frequency and severity of lightning surges imposed on the substation. The tower surge response adds an inductive 'overshoot' only during the front of the stroke which reduces considerably during the tail. If backflashover does not occur before reflections from adjacent towers arrive, it is unlikely to occur at all. Use of guys and underbuilt ground wires in the limiting distance will produce reflections with larger magnitude and reduce the effective surge impedance of the tower. This would not only reduce backflashover frequency but will also minimize crest and duration of surges entering the substation.

数値電磁界解析手法による鉄塔インピーダンスの検討

数値電磁界解析手法による鉄塔インピーダンスの検討

鉄塔サージ解析におけるループ電圧法の考察

鉄塔サージ解析におけるループ電圧法の考察

Digital computer studies of the surge response of a transmission line tower

In this paper, the transmission line tower response and behaviour are described when a lightning stroke terminates on the tower apex. The accompanied overvoltages on different points on the tower and under different conditions are covered. The effect of tower representation and modelling on the overvoltages produced and the tower travel time is also included.

Transmission line tower representation and its effect on the tower surge response calculation

In this paper, the transmission line tower response and behaviour are described when a lightning stroke terminates on the tower apex. The accompanying overvoltages on different points on the tower and under different conditions are covered. The effect of different tower representation and modelling on the overvoltages produced and the tower travel time is also included. The effect of back flashover on a phase conductor terminated by a GIS for a simplified tower is also investigated.

Travel Time of Transmission Towers

In prediction of HV and EHV lightning outage rates, the tower surge response consists of two parameters, the tower impedance and the tower travel time. Of the two, tower travel time has a larger effect on the predictions. A new model for tower travel time is developed based on the relationship between tower capacitance and tower surface area. Effects of tower crossarms and other features are modelled correctly by the new theory. When the new model is used, improved lightning outage rate prediction accuracy is obtained for 500kV single circuit lines.

Field Studies of the Surge Response of a 345-Kv Transmission Tower and Ground Wire

Field Studies of the Surge Response of a 345-Kv Transmission Tower and Ground Wire