Adjacent Towers Research Articles

Research on the spatial state and electrical distance variation of overhead transmission lines with changes in foundation

This article conducts a thorough investigation into the spatial state variations of overhead lines in response to foundational changes, as well as alterations in the electrical distance between the conductor and both the ground and tower structures. These changes are crucial for maintaining the stability and safety of the power system. By establishing an appropriate coordinate system and analyzing how tower sinking affects the position of overhead lines, this study examines the combined effects of multiple factors on the position of overhead lines. These factors include the degree of tower sinking, the elasticity and tension of the overhead lines, the positions and heights of adjacent towers, wind force, temperature, and other environmental elements. A mathematical model was developed to describe the positional changes of overhead lines following tower sinkage, and formulas were used to calculate the new suspension point positions and electrical distance variations of the wires. In addition, the effects of wire oscillations due to wind forces on the electrical clearance at tower heads and the impact of insulator string deviation on wire stability and safety were analyzed. Finally, a series of measures were proposed to ensure the safe operation of the power system.

Publisher’s Note: “Solution of electromagnetic scattering field of adjacent transmission towers based on reciprocity theorem” [J. Appl. Phys. 135, 075106 (2024)

Publisher’s Note: “Solution of electromagnetic scattering field of adjacent transmission towers based on reciprocity theorem” [J. Appl. Phys. 135, 075106 (2024)

Dynamic response of conductors during transmission tower failure under downburst loads

The frequency of thunderstorm-related failures of transmission lines has increased globally as a result of climate change. Downbursts are one of the High Intensity Wind (HIW) events associated with thunderstorms that have a detrimental impact on transmission towers due to their localized and non-stationary nature. When one tower fails, the conductors are subjected to dynamic excitation induced by the movement of the attached points to the towers which increases the tension forces in the conductors. If the adjacent towers are unable to sustain the increased tension forces, a cascade failure of multiple towers along the line is formed. The study aims to identify the conductor response to a tower failure under downburst loads using nonlinear dynamic analysis. The reactions transferred to the adjacent towers due to the tower failure are reported as well. The effect of varying the downburst jet velocity and the failure location within the tower height are investigated. The results show that the conductor response to the dynamic excitation of the tower failure depends on the velocity of the tower movement, the magnitude of the transverse load on the conductors, and the failure location along the tower height. The tension forces in the conductors and the reactions at the adjacent towers increase considerably due to the tower failure that can cause the failure of the adjacent towers.

Solution of electromagnetic scattering field of adjacent transmission towers based on reciprocity theorem

Due to the large number of transmission towers being built, the dense distribution of transmission towers is inevitable in some areas. Densely distributed transmission towers will generate severe electromagnetic coupling, which will affect the setting of the passive interference protection distance between transmission towers and adjacent radio stations. Therefore, based on the traditional algorithm for solving the electromagnetic scattering field of a single electrically large target in wide area space, the electromagnetic coupling effect between multiple adjacent transmission towers within a range of 10 times the signal wavelength was considered. Based on the reciprocity relationship between the scattering electric field and the source and the introduced auxiliary field source as the intermediate variable, the electric field integral equation of the secondary scattering field generated by the electromagnetic coupling effect of adjacent transmission towers was derived, and the secondary scattering field is superimposed with the primary scattering field of the transmission generated by the electromagnetic wave excitation of the radio station, obtaining the electromagnetic scattering field at any point. In order to verify the accuracy of the algorithm proposed in this article, the scaled model experiments for the electromagnetic coupling effect between two transmission towers in an anechoic chamber were conducted. The average error of the algorithm proposed in this article is 6.73%, while the error of traditional algorithms is 20.18%. Compared with the traditional algorithm, the accuracy of the proposed algorithm is improved by 13.45%.

Influence and the Control of Shield Tunneling on Ancient Tower Vibration

In recent years, to effectively mitigate the issue of urban traffic congestion, tunnels have become widely used new type of road. However, when the soil layer is excavated and disturbed, the resulting vibration affects the safety of the buildings above it, especially for ancient buildings that are very sensitive to vibrations. Taking the White Tower in Hangzhou as an example, in this paper, the vibration response propagation of large-diameter shield tunnel excavation to adjacent ancient towers is studied through field measurements. The vibration response of the unexcavated south line tunnel is predicted by using 3D numerical analysis software, and the optimal construction parameters are obtained. The study found that the frequency domain component of the White Tower bedrock vibration caused by shield tunneling is mainly 5–20 Hz, and the vibration response attenuates significantly beyond 40 m. Further, reducing the propulsive force can reduce the vibration response of the White Tower; therefore, controlling the propulsion and reducing the tunneling velocity can reduce the vibration response.

Numerical study identifies the interaction between two adjacent dry cooling towers on fluid flow and heat transfer performances of the radiators at different points of each tower

A reliable thermal power plant in arid area usually has twin power-generating units equipped with two dry cooling towers. For a twin-tower configuration, a three-dimensional numerical model was built to capture thermo-hydraulic characteristics of both towers and distribution patterns of heat transfer performances of their radiators. Results showed that the interaction between two adjacent towers is a combination of negative blocking effect and positive wind-breaking effect of one tower to another, and its influences on radiators of different orientations are distinct and dependent on wind direction and speed. As wind attack angle increases, the overall cooling performance of the upstream tower improves and its sensibility to wind speed declines, while performance variation of the downstream tower shows a decrease followed by an increase. The downstream tower performs worse than the upstream tower in most crosswind cases, except for the wind situation where the downstream tower is almost entirely blocked by the upstream one. For a given wind speed of 12 m/s, cooling efficiency of the upstream (downstream) tower rises from 69.4% to 73.7% (91.7%) as wind attack angle varies from 0° to 90°, causing condenser pressure of the associated power unit to reduce from 23.5 kPa to 20.5 kPa (14.4 kPa). As the tower spacing increases, the tower interaction mitigates and cooling performance difference between the two towers narrows. The decrease of ambient temperature barely impacts cooling efficiency of the tower, but does cause a drop in condenser pressure of the unit without changing the sensitivity of condenser pressure to crosswind. The increase in condenser heat load helps to improve cooling tower performance and reduces its sensitivity to crosswind. Whereas, the growth in condenser heat load dominates the increases in condenser pressure and its sensitivity to crosswind.

A closed-form solution for the wind-induced responses of transmission lines considering the failure of adjacent towers

Some towers in transmission lines may collapse first under the gust wind and have pulling effects on conductors, which may trigger the cascade failure when the unbalanced force on the adjacent tower is large. Thus, a closed-form solution is proposed to predict conductor responses induced by both the failed tower and wind loads. The total wind-induced response is divided into the mean component affected by support displacement and fluctuating component around the static equilibrium, which can be determined by nonlinear static analysis and influence line, respectively. The equilibrium iteration method and trapezoidal equivalent wind pressure are proposed to correct the response distortion caused by the large deformation and non-uniform wind pressure. Then, the power spectral density and root mean square of responses considering three-dimensional correlation are provided. Finally, parameter analysis investigates the influence of support displacement, initial horizontal tension, and horizontal span on reaction force and gust response factor (GRF). The results show that the proposed closed-form solution has high accuracy and efficiency, and the influence of large deformation and wind pressure forms on the wind-induced responses cannot be ignored. Moreover, both the lateral reaction force and GRF are significantly sensitive to the lateral support displacement.

Numerical model of cascade failure of transmission lines under downbursts

Transmission line’s cascades have played a major role in several serious accidents around the world, as they are particularly prone to occurring in the presence of strong winds. The failure of a line component overloads the system, inducing a progressive failure that can involve many transmission line (TL) supports. Due to their localized nature, downbursts, in particular, cause unequal wind forces on various towers of a transmission line; the collapse of one tower can affect the adjacent towers through the unbalanced forces that develop in the conductors, which can lead to a cascaded-type of failure along the entire line. In this study, a numerical model is developed in-house to predict this type of line failure. A major challenge in this numerical model is the prediction of the geometric configuration of the tower and of the conductor forces after the tower collapses. Details of this unique numerical model are presented in this paper along with a case study for illustration.

Performance-Based Compositive Passive Control Analysis of Multi-Tower Building with Chassis: Optimization of Kelvin-Voigt Dampers

The compositive passive control (CPC) method of “interlayer seismic isolation “plus “shock absorption between adjacent towers” was applied to a multi-tower building (MTB) with a large podium. The interaction between adjacent towers was used to reduce the structural response under seismic action. Based on the Clough–Penzien spectral seismic model, the extended state equation of random response of MTB was derived with the minimum total energy of structural vibration as the optimization control objective. By comparing the seismic scheme and interlayer seismic isolation scheme, the relationship between the control parameters of the connecting control device and the random response of the structure was discussed and analyzed, and the control effect of the composite passive control system under different control schemes was also studied from the perspective of seismic response time history and vibration cumulative energy time history. Through numerical analysis, it was proved that the damping coefficient of the Kelvin-Voigt model has a great influence on the mean square error of total vibration energy while the stiffness coefficient has a poor sensitivity to it. Under the optimization control objective, the connection control device was better arranged at the top of the structure. The control effect can reach 84.64% under the condition of random ground motion as input. The CPC method maintains the advantages of the interlayer seismic isolation scheme and reduces the defect of the response amplification caused by the interlayer isolation, which provides a reference for the follow-up study of the CPC method of MTB.

Hybrid Isolation Strategy for Seismically Isolated Multi-Tower Building with a Large Podium

The Compositive Passive Control method (CPC method) of “interlayer seismic isolation” + “shock absorption between adjacent towers” is applied to Multi-Tower Building (MTB) with a large podium. Taking the total vibration energy of the structure as the optimal control objective, the response expressions of a multi-DOF layer shear model and an equivalent single-DOF layer shear model are derived. The rationality of the equivalent model is demonstrated from the perspective of mode characteristics and time history response. Based on the Kanai–Tajimi spectral seismic motion model, the control effect and the optimal control parameters of the CPC method are studied. Compared with the conventional seismic scheme and the interlayer seismic isolation scheme, the influence of the CPC method on the structure natural vibration characteristics and dynamic response under different parameters of the connecting control device is discussed and analyzed. The numerical analysis proves that the CPC method provides a significant damping effect compared with the interlayer seismic isolation scheme. It maintains the advantages of the interlayer seismic isolation scheme and reduces the defect of the response amplification caused by the interlayer isolation. This analysis constitutes a good reference for the follow-up study of the CPC method of MTB.

Optimal placement of surge arresters for transmission lines lightning performance improvement

Installation of transmission line surge arresters (TLSA) is one of the solutions found to improve the lightning performance of overhead transmission lines (OHTL). This work proposes a new multi-criteria methodology for the optimal placement of surge arresters on OHTL based on a multi-objective optimization algorithm coupled with ATP (Alternative Transient Program) software. Lightning performance calculation is performed considering the transfer effect of the lightning surge due to arresters operation. This transfer mechanism that can lead the adjacent towers to flashover is rarely mentioned in the literature. A case study considering a 230 kV transmission line with 231 towers and 105 km long operating in Brazil is presented. Compared to the real performance data, the solution found with the best cost-benefit ratio allows a reduction of 68% in the line outages with the use of 90 surge arresters (i.e., 0.86 TLSAs/km of line). This is practically 50% of the number of arresters calculated using the classical placement method based on the tower-footing impedance value. Regarding the transfer effect of the lightning surge, the results show that the performance levels and, consequently, the number of TLSAs to protect the line may be underestimated if this effect is not considered in the modelling.

Howland Forest, ME, USA: Multi-Gas Flux (CO2, CH4, N2O) Social Cost Product Underscores Limited Carbon Proxies

Forest carbon sequestration is a widely accepted natural climate solution. However, methods to determine net carbon offsets are based on commercial carbon proxies or CO2 eddy covariance research with limited methodological comparisons. Non-CO2 greenhouse gases (GHG) (e.g., CH4, N2O) receive less attention in the context of forests, in part, due to carbon denominated proxies and to the cost for three-gas eddy covariance platforms. Here we describe and analyze results for direct measurement of CO2, CH4, and N2O by eddy covariance and forest carbon estimation protocols at the Howland Forest, ME, the only site where these methods overlap. Limitations of proxy-based protocols, including the exclusion of sink terms for non-CO2 GHGs, applied to the Howland project preclude multi-gas forest products. In contrast, commercial products based on direct measurement are established by applying molecule-specific social cost factors to emission reductions creating a new forest offset (GHG-SCF), integrating multiple gases into a single value of merit for forest management of global warming. Estimated annual revenue for GHG-SCF products, applicable to the realization of a Green New Deal, range from ~$120,000 USD covering the site area of ~557 acres in 2021 to ~$12,000,000 USD for extrapolation to 40,000 acres in 2040, assuming a 3% discount rate. In contrast, California Air Resources Board compliance carbon offsets determined by the Climate Action Reserve protocol show annual errors of up to 2256% relative to eddy covariance data from two adjacent towers across the project area. Incomplete carbon accounting, offset over-crediting and inadequate independent offset verification are consistent with error results. The GHG-SCF product contributes innovative science-to-commerce applications incentivizing restoration and conservation of forests worldwide to assist in the management of global warming.

Viscous inertial mass damper (VIMD) for seismic responses control of the coupled adjacent buildings

Many research studies have focused on a novel kind of damper involved with an inertial/gyro mass component, called the inertial mass damper (IMD). Different realizations of the IMD share common standard features: a sizeable apparent mass and the pseudo-negative dynamic stiffness. The connected control method (CCM) has been proven effective for mitigating vibration between adjacent flexible structures. This paper explores the efficacy of using an IMD in parallel with a viscous damper (termed VIMD) configured in the sky bridge to control the vibration of two adjacent towers under random earthquake excitation. First, numerical models of two buildings are developed using a Timoshenko beam model, which can accommodate both bending and shear deformation. Key damper parameters are explored through a parametric study. Then, stochastic optimization is performed to determine optimum damper parameters and the most effective configuration. The optimization results are analyzed in detail, and guidelines for the damper configuration are recommended. By comparing the optimal control performance between the VIMD and traditional viscous damper (VD), the following conclusions can be drawn: due to its pseudo-negative stiffness characteristics and large damper force, the VIMD can achieve better control performances for a wide range of the axial stiffness of the sky bridge; the VIMD requires a smaller damping coefficient and axial stiffness, which can result in smaller damper sizes and member sections of the sky bridge. Therefore, the VIMD is demonstrated to be a useful alternative for engineering practice in CCM vibration mitigation strategies.

Dynamic Analysis of Power Transmission Lines With Ice-Shedding Using an Efficient Absolute Nodal Coordinate Beam Formulation

Abstract Dynamic analysis of power transmission lines with ice-shedding is conducted in this work. The power transmission line is first simplified as a uniform slender round beam. While the beam can have large displacements, rotations, and deformations, its strains are assumed to be small. The bending stiffness of the transmission line is considered here, but its shear and torsion effects are neglected. An efficient absolute nodal coordinate beam formulation is developed based on the above assumptions, and the number of generalized coordinates of each element of the beam is reduced to the least. The mass matrix is constant and the generalized elastic force is evaluated by constant stiffness tensors and generalized coordinates; hence, the current formulation is very efficient. Dynamic responses of power transmission lines with ice-shedding are then calculated. A benchmark planar two-span line is first considered, and the results are validated by the commercial finite element software abaqus. By examining strain states of the transmission line, it is found that its bending stiffness cannot be neglected in this dynamic analysis. Dynamic analysis of a three-dimensional three-span line is then conducted, where towers are not in a straight line and elevation differences between adjacent towers are considered. Several cases with common ice detachment mechanisms are considered, and dynamic responses of the cable and reaction forces of insulators due to ice-shedding are analyzed.

Green Base Station using WSN

Since the number of mobile users has been increased, there comes a number of new mobile operators. This accounts for the increased installation of towers. A critical mobile network consume 40-50MW (approx.) and a diesel generator consume 1MG (approx.) of diesel per day. Also a base station requires greater amount of power employed for its working in which some of its internal applications like light, coolant systems say air conditioning, fans etc., uses the major part of the power utilized. This intensifies the burning of coal which emits carbon dioxide into the atmosphere. At times the number of users for a base station may be very less especially during night time, consuming the power unnecessarily. Our approach is to reduce the intake of power by the base stations during unwanted time. This can be done by establishing communication between the adjacent towers to intimate the unused tower to remain idle or active based on the requirement. Also this approach conveys the measures taken to reduce the power consumed by the internal applications of the base station. The entire setup is under the surveillance of personal computer thereby creating an energy efficient mobile infrastructure with power saving, reduction of CO2 emission which in turn reduces global warming and successful operation of large scale mobile communication services.

Constraints on the use of surge arresters for improving the backflashover rate of transmission lines

The effectiveness of using transmission line surge arresters (TLSA) under different conditions for improving the lightning performance of lines is assessed by means of computational simulation. These conditions comprise using TLSA only in critical towers and/or using devices only in certain phases, leaving one or two-phases unprotected. In addition to assess the effect on stricken towers, the transfer of overvoltage to unprotected adjacent towers is also addressed, considering different values of tower-footing impedance. In the analyses, lightning overvoltages across insulator of typical single-circuit 138-kV and double-circuit 230-kV transmission lines were calculated by using the Hybrid Electromagnetic Model (HEM) and flashover occurrence was assessed by using the Disruptive Effect method (DE), in each simulated condition. The results indicate that the operation of TLSA protects the own insulator and diminishes the backflashover risk at unprotected insulators. However, this risk remains high, depending on tower-footing impedance. Also, the risk of flashover at the unprotected adjacent towers due to the operation of surge arresters at the stricken tower was found to be significant in the case of all phases of the stricken tower protected, notably when the tower-footing impedance of the protected tower is high and that of the adjacent tower is low.

АРХІТЕКТУРНІ ЗМІНИ ЖОВКІВСЬКОГО ЗАМКУ – ОБОРОННОЇ СПОРУДИ ЧАСІВ ЯНА СОБЄСЬКОГО

In this article the history of architectural transformations that took place in Zhovkva castle during the management of Yan Sobieski is traced. In particular, the state of the investigated object in the given of historical period is characterized on the basis of already known primary sources – plans, inventory descriptions, financial books and other written materials, as well as the whole spectrum of scientific developments on this issue of domestic and foreign science. An attempt was made to reconstruct the appearance of the castle in the complex with the data of archaeological and architectural research, as a result of which the chronology and the list of works, as well as the names of the masters involved in the process of the reconstruction of the Zhovkva castle in the times of Jan Sobieski, were specified in detail. This study made it possible to distinguish several main periods of castle modification in the given chronological framework: the pre-royal period, which was characterized by minor changes; early royal – perestroika, which were occasional; the late royal period is the cardinal transformation of a well-fortified castle into a lush Baroque residence.The key place in these processes of modification of the object under study was the artistic tastes of Jan III Sobski, the level of education, as well as the change in the socio-legal status of the host. Just after his accession to the throne of the Rzeczpospolita, the castle of Zhovkva has become key, being one of the king's main residences, which in turn prompted him to change his appearance with bringing to the best European models.In particular, the article identifies the major transformations in the palace building with adjacent towers, defines the list of interior finishing works, establishes the probable time for the construction of large parade stairs, outlines a complex of works for the construction of the castle arsenal, laying and arrangement of the park.

Rain Rate Retrieval Test From 25-GHz, 28-GHz, and 38-GHz Millimeter-Wave Link Measurement in Beijing

Accurate rainfall monitoring is important, and previously it has been shown that microwave backhaul link between adjacent base station towers can be used for rainfall estimation. However, with the deployment of 5G using millimeter technology, there is opportunity for dense rainfall monitoring network using both backhaul and data transmission links. This paper presents our millimeter-wave measurement results during rainy days in Beijing, China. Our measurement design is an exemplary line-of-sight transmission link. We show that it is possible to retrieve the path-averaged rain rate from the measurement and to use both millimeter-wave transmission link and backhaul link to assist rainfall monitoring. Compared to the local rain measurement from rain gauge and disdrometer, we show that the correlation value of millimeter-wave link retrieved average rain rate varies between 0.6 and 0.9 for different rainfall events. There is room for improvement, and we find that if we can monitor the received signal for a sufficiently long period of time, we can quantify the bias due to fading and work out a better estimate of the rain retrieval model's reference level.

Seismic performance of buildings retrofitted with nonlinear viscous dampers and adjacent reaction towers

SummaryAn effective strategy of seismic retrofitting consists of installing nonlinear viscous dampers between the existing building, with insufficient lateral resistance, and some auxiliary towers, specially designed and erected as reaction structures. This allows improving the seismic performance of the existing building without any major alteration to its structural and nonstructural elements, which makes this approach particularly appealing for buildings with heritage value. In this paper, the nonlinear governing equations of the coupled lateral‐torsional seismic motion are derived from first principles for the general case of a multistory building connected at various locations in plan and in elevation to an arbitrary number of multistory towers. This formulation is then used to assess the performance of the proposed retrofitting strategy for a real case study, namely, a 5‐story student hall of residence in the city of Messina, Italy. The results of extensive time‐history analyses highlight the key design considerations associated with the stiffness of the reaction towers and the mechanical parameters of the nonlinear viscous dampers, confirming the validity of this approach.

Tower-Footing Resistance and Lightning Trip-outs of 150 kV Transmission Lines in West Sumatra in Indonesia

The trip-out rates calculated by taking account of the reduction in the tower-footing resistance due to the ionizing effect agree well with the observed ones. This indicates the importance of the impulse resistance in the analysis of the lightning performance of the line. The trip-out rate at the lower arm is high for the cases of the average grounding resistance of 33.3 ohms, and the rates at the upper arm are high for the cases of the average grounding resistance of 5.6 ohms. Such à trend can be simulated by the IEEE method using the impulse resistance. The trend for the trip-out ratio to become high with the increase in the span length is significant after improvement of the tower-footing resistance. However, the trend is weak before improvement of the tower-footing resistance. This is because in the case of the high tower-footing resistance the flashover occurs before the arrival of the wave reflected from the adjacent towers due to the high potential rise of the tower. Therefore, the degree of the influence of the span length on the trip-out ratio is dependent on the tower-footing resistance. The local lightning activity significantly affects the trip-out rate.