Analysis of lightning surge characteristics for transmission towers (original) (raw)
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Experimental study on lightning surge response of 500kV transmission tower with overhead lines
2009
This paper presents the measurement of the lightning surge response of a 500-kV transmission tower with overhead lines including ground wires and phase wires. A number of experimental studies on the lightning surge response of transmission towers have been carried out using freestanding structures such as scale models or actual transmission towers. However, these experiments have ignored the effects of transient electromagnetic coupling among the injection current, the overhead lines, and the tower. This paper reports a new method of measurement considering the arrangement of an actual tower and overhead lines. It is clearly shown that the measured voltage waveform across insulator strings at each crossarm depends on the direction of the injection current. Moreover, the measured current value flowing into the ground wires varies with the direction of the injection current. These results predict that the surge response of a transmission tower depends on the direction of the return stroke current. This is important for the modeling of towers with overhead lines and the estimation of the lightning performance of transmission systems under a lightning stroke.
This paper presents three alternatives for modeling sections of overhead transmission lines for surge propagation studies. The analysis takes into account the simulation of cables, towers and grounding systems by the computer program FDETP, combining both circuit and three-dimensional electromagnetic field models. From the gotten results, it is clear that reasonably accurate modeling can be obtained by simulating the line by a very simple circuital approach.
Accuracy of Lightning Surge Analysis of Tower Surge Response
This paper presents a comparison between the measured and calculated results of tower surge response for verifying the accuracy of lightning surge analysis. These calculated results are obtained using the Finite Difference Time Domain (FDTD) method and the Electromagnetic Transients Program (EMTP). Injection current waveforms and voltage waveforms across insulator strings of the transmission tower were measured when a rectangular impulse current or a current with the rise time of 1µs were injected into the top of the tower. The measured waveforms of voltage across insulator strings are compared with the calculated voltage waveforms using the FDTD method. The calculated waveforms can reproduce the measured waveforms, and as a result, it is verified that the FDTD method is effective in a lightning surge analysis. The influences of the geometrical arrangement of phase wires, the ground resistivity and the slope of ground on the accuracy of a surge simulation are also investigated using...
Computation of Lightning Voltage Surges on Tall and Conventional Transmission Towers
2020
Transmission tower modelling is very important to assess the electromagnetic transient caused by lightning strikes in power systems. In this context, conventional tower models are very well studied in the literature. However, there are few studies on tall transmission towers which have been receiving great attention recently due to their own characteristics. Tall transmission towers are built on river crossings and/or over dense forest canopy to reduce environmental impact in these areas. In this paper, the voltage surge caused by an incident lightning at the top of the conventional and tall towers are determined. For both structures, a lumped electric circuit approximated by Vector Fitting technique is proposed which takes into account the tower-footing grounding system buried in different homogeneous soils. The results show a clear difference in the time domain voltage response for the conventional and tall transmission towers which is more pronounced as the soil resistivity incre...
Simulation of lightning surges on tower transmission using PSCAD/EMTDC: A comparative study
Student Conference on Research and Development, 2002
This paper describes the analytical and the experimental responses of the surges strike on the transmission line towers. A new method of calculating transmission tower surge response has been proposed. It has been found that the tower surge response calculated by the proposed method has a close agreement with the measured tower surge response obtained from scale model and field tests. Without the use of simulation program, this topic might be difficult to understand. PSCAD/EMTDC has been selected as the software used to generate the appropriate data needed to graphically demonstrate this phenomenon.
2021
When lightning strikes a transmission line tower or shield wires, electromagnetic waves propagate through the tower back and forth, increasing the voltage across insulator strings. This can eventually lead to a back-flashover (BF), which may cause damage to equipment or costly power outages. To calculate the over-voltages and predict the probability of a BF, an accurate model of the tower and its grounding system is needed in electromagnetic transient (EMT) type simulators. There are a number of theoretical models for the equivalent circuit of a transmission tower. However, they either are not accurate enough or they are derived for a certain type of transmission tower, which limits their applicability. Numerical electromagnetic analyses have less simplifications compared to the theoretical solutions and are by far less expensive than field measurements. They also have the flexibility to analyse any type of tower. In this paper, the direct method for the measurement of tower impedan...
2017
An approach using fitting techniques is proposed for modeling of tall steel towers for analysis of the lightning performance of transmission lines. The frequency-dependent surge impedance of a steel tower is modeled in the time domain using fitting techniques and an equivalent electric circuit composed of lumped elements. The proposed tower model is validated based on results obtained using the well-established Numerical Electromagnetic Code-NEC and inverse transforms. The contribution of the proposed model is the development direct in the time domain, enabling further interactions of the tower modeling with other time-variable power elements in the transmission system. Emphasizing that most of the transient events in power transmission systems are well-established in the time domain as time-variable elements during modeling and simulation processes. This same statement is not true in the frequency domain.
s-Domain analysis of lightning surge response of a transmission tower with phase conductors
Lightning surges on a transmission tower with a shield wire and phase conductors are analyzed using an sdomain method. The voltages induced on the phase conductors and surges at the position of the tower crossarms are computed to obtain the insulator voltages. Response of the system determined in the s-domain is transformed into the time domain using Fast Inverse Laplace Transform (FILT). It has been shown that lightning surge response of a transmission tower can be determined easily using Coupling Coefficient Matrix (CCM) defined in this paper. The solution procedure is programmed with MATLAB. The results obtained using the proposed method are compared with those obtained using Electromagnetic Transients Program (EMTP).
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.