Power Transmission Structure Research Articles

Nonlinear Finite Element Analysis and Fatigue Damage Assessment of Wind-Induced Vibration for the Tension Cable-Supported Power Transmission Structure

Nonlinear Finite Element Analysis and Fatigue Damage Assessment of Wind-Induced Vibration for the Tension Cable-Supported Power Transmission Structure

Impacts of Trans-Provincial Thermal Power Transmission on Air-Quality Recovery and Related Health Outcomes in China.

Trans-provincial thermal power transmission has become an important measure for optimizing power allocation and alleviating the mismatch between regional power production and consumption in China, however, leading to inter-regional redistribution of air pollution. Here, we investigated the impacts of thermal power transmission on air-quality recovery and related health outcomes in China. The results showed that the redistribution of air pollutant emissions contributed to air-quality improvements and health benefits in the eastern regions but to the opposite side in the western regions. On a national scale, trans-provincial thermal power transmission contributed to a change in air quality from slightly polluted to good conditions for a period of 9 days under the standard of 75 μg m-3, accounting for 1.8% of the total number of polluted days in 4 months of 2017 and promoting air-quality recovery in China. Furthermore, the recovery totally reduced the number of premature deaths (exposed to fine particulate matter, PM2.5) by 2392 persons (95% confidence interval: 1495-3124) in 2017. Owing to thermal power retrofits and stable power transmission structure, transmission network expansion during the last decade has not brought significant changes in its impacts on air pollution. However, the environmental inequity caused by thermal power transmission stimulates further attention on coordinating regional interests in air pollution control through various production-side and consumption-side measures.

Review on power flow and efficiency of a closed differential planetary gear train

The closed differential planetary gear train transmits power in multiple paths, which has large power transmission and compact structure. It is widely used in high-power occasions such as ships. However, the closed differential planetary gear train has many power flow paths and complex structure. If the structural design is unreasonable, there will be power cycle (closed power) in the system, which will seriously reduce the efficiency of the system. There are many components of closed differential planetary gear train, and the uniform distribution of load is of great significance to improve the transmission quality and service life of the system.This paper mainly summarizes the research status of ordinary planetary gears, the power flow analysis status of closed differential planetary gear transmission and the efficiency analysis status of planetary gear transmission.

Who shapes the embodied carbon dioxide emissions of interconnected power grids in China? A seasonal perspective

With the rapid development of interregional power transmission, the redistribution of fossil and renewable energy resources has changed sharply, and its complexity poses a challenge to the evaluation of power carbon emission responsibility. This study constructs an interprovincial power transmission framework to measure the seasonal carbon emissions embodied in regional electricity consumption over the period of 2008–2015 based on quarterly data. Then, a structural decomposition approach was developed to identify the influential factors of carbon emissions embodied in provincial electricity consumption from a seasonal perspective. The results show that the assessment for embodied emissions of power consumption based on different levels of data may vary by as much as 20%, and the carbon emissions and carbon intensity of power consumption exhibit significant seasonal characteristics. Furthermore, it is revealed that the economic scale in the fourth quarter makes the most significant contribution to the emissions increment, especially in underdeveloped provinces, while the change in energy efficiency of power generation reduces more carbon emissions in the first and second quarters. In addition, the impact of the power transmission scale is more significant in the third and fourth quarters, and it has been close to or even more than the impact of traditional factors in some quarters. Finally, the impact of economic scale, power generation energy intensity, power generation mix and electricity utilization efficiency on the emissions of regional power grids shows a relatively stable increasing trend, but this trend of directional stability is not reflected in the effect of the power transmission structure and transmission scale. This study contributes to the identification of the impact of the power transmission structure and transmission scale. Moreover, this study highlights the importance of considering seasonal characteristics when estimating the carbon emissions of power consumption and formulating specific emission reduction policies. Additionally, it provides a more accurate evaluation of carbon emissions and proposes several prominent recommendations for policy makers.

Real Power Loss Reduction by Accipitridae Optimization Algorithm

In this paper, Accipitridae Optimization Algorithm (AOA) is used to solve the power loss lessening problem. Authorizing a satisfactory magnitude of reactive power is effervescent for the steadfast operation of power transmission structures, as the power meagreness may tip to staid power catastrophe and leading power upheavals. Loss reduction problem is intended as one of the prominent conditions for compassionate and financial action of edifice. It is exceptional by appropriate union of the network apparatus castoff to deal with up the power flow with the dispassionate of decreasing the losses and evolution the power outline of the assemblage. Plentiful previous studies unravelled the power problem as the optimization objective tasks premeditated noticeably. Real power loss reduction, Voltage stability expansion and voltage deviation minimization are the key objectives of the work. Hunting methods of Accipitridae are imitated to design the Accipitridae Optimization Algorithm (AOA). Accipitridae does hunting in a single-mode on the prey. High ascend with a perpendicular bend down towards the prey will be done by the Accipitridae. High ascend with a perpendicular bend down towards the prey will be done by the Accipitridae is formulated. As soon as the prey spot is precise then Accipitridae is geared up for landing and assault, the Accipitridae move down perpendicularly with a preface assault to determine the prey response. AOA initiates the upgrading measures by engendering an arbitrary solution. In the course of the curve of reiteration, the explore stratagem of the AOA is the rational location of the most excellent optimal solution. The authenticity of the Accipitridae Optimization Algorithm (AOA) is corroborated in IEEE 30 bus system (with and devoid of L-index). Genuine power loss lessening is attained. Voltage stability escalated with minimization of power deviance. Then the proportion of actual power loss lessening is amplified.

Current Tracking Control of Triple Active Bridge DC/DC Converter Under Varying DC-Bus Voltage Conditions

A triple active bridge (TAB) converter consisting of three full-bridge inverters and a three-winding transformer has been researched to improve its power conversion performance as a bi-directional isolated multiport converter. Previous research established a current control method using a decoupling system to solve the complex power transmission structure of the TAB converter. However, it is challenging to integrate voltage factors into the decoupling system because DC-bus voltages of the TAB converter are assumed to be constant. Active bridge control against voltage variations has become essential to achieving high-performance DC/DC power conversion systems using high-frequency transformers such as a TAB converter. This paper proposes a TAB converter control method, which is an expansion of the conventional method, to integrate the DC-bus voltage variation into the control model. Model predictive control is used to achieve tracking control by incorporating voltage variation factors into the control method using an established model structure as a basis for predictive calculations. Simulations were conducted to verify that the proposed method improves the output responses compared to the conventional methods when the DC-bus voltages change. Also, experiments using a prototype converter show that the proposed control method can achieve current tracking control during the voltage variation.

Finite Element Analysis on Behavior of Reinforced Hollow High Strength Concrete Filled Square Steel Tube Short Columns under Axial Compression

Hollow concrete-filled steel tubular (CFST) member is mainly adopted in power transmission and transformation structures, but when it is used in the superstructure with complex stress, the hollow CFST member has a low bearing capacity and is prone to brittle failure. To improve the mechanical performance of hollow CFST members, a new type of reinforced hollow high strength concrete-filled square steel tube (RHCFSST) was proposed, and its axial compression performance was researched. 18 finite element analysis (FEA) models of axially loaded RHCFSST stub columns were established through FEA software ABAQUS. The whole stress process of composite columns was studied, and parametric studies were carried out to analyze the mechanical performance of the member. Parameters of the steel strength, steel ratio, deformed bar and sandwich concrete strength were varied. Based on the simulation results, the stress process of members can be divided into four stages: elastic stage, elastoplastic stage, descending stage and gentle stage. With the increase of steel strength, steel ratio, the strength of sandwich concrete and the addition of deformed bars, the ultimate bearing capacity of members also increases. Additionally, the increment of those parameters will improve the ductility of the member, except for the sandwich concrete strength.

Hierarchical control of mid-long term voltage stability in a hybrid multi-infeed HVDC system

With the emerging use of VSC-HVDC links, the hybrid multi-infeed HVDC (HMIDC) system that includes LCC-HVDC and VSC-HVDC links appears and is becoming a promising power transmission structure in modern power systems. In order to make full use of the fast power adjustment capability of VSC, mitigate commutation failures and keep the voltage stability of the AC power grid, this paper proposes a hierarchical control strategy of long-term voltage stability in a HMIDC system. The converter control coordinates control variables including VSC-HVDC reactive power, shunts, and inverter extinction angle to ensure safe operation of LCC-HVDC. The system level is a model predictive control based on trajectory sensitivity with the objective of minimizing the deviation of voltage trajectories and the control cost, which coordinates the AC and DC control variables to ensure the safe operation of the AC system. The simulation results of a HMIDC system show that the control method proposed in this paper can fully coordinate all kinds of control methods of AC/DC system, improve the long-term voltage stability of the system.

Computer software for analysis and design optimization of power transmission structures by simulated annealing and sensitivity analysis

This paper presents a computer software for the optimization of power transmission structures. The software employs a modified version of the Simulated Annealing algorithm that has been proven effective in large engineering problems. The target structures are three-dimensional steel trusses to be used as supporting towers of electrical lines. A mixed formulation merging continuous and discrete design variables is proposed for optimizing the size and shape of the trusses, including a first-order sensitivity analysis that reduces the computational cost. The implementation can be adapted to any kind of transmission tower and allows to quickly create a model to be analyzed and optimized in a few sequential steps. Despite its simplicity of use, the tools provided by the proposed framework allow to perform a full analysis of the design and provide an entire comprehension of its structural behavior. The software also includes a post-process and visualization tool set in a user-friendly graphical interface.

Multi-scope electricity-related carbon emissions accounting: A case study of Shanghai

Abstract Electricity-related carbon emissions in a specific region can vary significantly as the scope for emissions accounting changes. Existing studies have mainly focused on carbon emissions caused by local power generation (Scope 1) and carbon emissions embodied in the electricity consumed by a region after cross-regional electricity transmission (Scope 2). Previous studies have ignored the electricity-related carbon emissions induced by regional consumption (Scope 3), leading to carbon emissions leakage. Comprehensively employing the IPCC emissions accounting method, a network approach that simulates cross-regional electricity flow and an environmentally extended input-output model, this study provides systematic electricity-related carbon emissions accounting for regional electricity-related carbon emissions under Scopes 1, 2 and 3 using the case of Shanghai in the period of 2007–2012. The results show that Shanghai has large net inflows of electricity-related carbon emissions through power grids and regional trade, causing Scope 2 and Scope 3 emissions to be significantly larger than Scope 1 emissions in Shanghai. A Logarithmic Mean Divisia Index (LMDI) model is used to analyze the driving factors of carbon emissions under Scope 1, and the driving factors of carbon emissions under Scopes 2 and 3 are evaluated using structural decomposition analysis (SDA). Fuel structure improvement can help to reduce Shanghai’s Scope 1 emission, while the power generation volume increase has opposite effect. Power transmission structure and power transmission scale decrease Shanghai’s Scope 2 emissions, while the power consumption scale is positive with emission growth. The declining carbon emissions intensity and improving electricity efficiency offset the growth of Shanghai’s Scope 3 emissions, while the increase in population and per capita electricity consumption contribute to the increase in Scope 3 emissions. This study could help to enhance the understanding of regional electricity-related carbon emissions and to support comprehensive and systemic carbon mitigation strategies.

Research and design of new type photovoltaic vacuum insulation cup

Aiming at the problem of limited insulation time of vacuum insulating cup, the modification and design of new photovoltaic vacuum insulating cup are completed, including selection of heating material, selection of power supply of photovoltaic insulating cup, power transmission and overall structure design. Compared with similar research, this paper focuses on the selection of heating materials and the use of wireless transmission devices to solve the problem of thermal insulation. In this paper, the structure of photovoltaic insulating cup is studied, and the optimum heating material is discussed. Combined with photovoltaic power supply and wireless power transmission technology, the design of insulation Cup is completed, and the insulation performance of this design is verified for more than ten hours.

Drivers of CO2 emissions from power generation in China based on modified structural decomposition analysis

Currently, over 20% of global electricity and 30% of global CO2 emissions from fuel combustion are generated in China. Understanding the driving forces of CO2 emissions from power generation is critical for both decarbonizing the power sector and achieving national carbon reduction targets. The objectives of this study were to identify critical driving forces behind changes in CO2 emissions from the power sector and to propose appropriate decarbonization pathways. First, the generation and demand structures of the power sector were introduced into a CO2 emission accounting model and decomposition analysis. Instead of traditional input–output analysis, structural decomposition analysis modified using a power transmission table was used to investigate the impacts of five driving factors of CO2 emissions from China’s power generation. The five driving factors comprised the proportion of thermal power, power generation technology, power generation structure, power demand structure and power demand, whereby the latter was divided further into nine detailed parts. Considering five regional power grids in China, the contributions of these factors were analyzed at both national and regional level. The results showed that the majority of the increase in CO2 emissions during 2007–2012 could be attributed to electricity generation (96.2%) driven by changes in power demand, which should be the key to power sector decarbonization. By contrast, 30.7% of emissions were offset by changes in the proportion of thermal power and technology, demonstrating the obvious effects of China’s policy on clean energy transition. Additionally, all power grids exhibited an increase in CO2 emissions from electricity generation, with the east and central grids accounting for 64% of the national increase. Power transmission structure had only a small impact on CO2 emissions from power generation. By using the electricity transmission table, we modified SDA to overcome the time lag issues and eliminate the reliance on IO data, and continuous annual data rather than aggregated five-yearly data can be used to capture the structural effects, thus providing more precise results for the driving forces of emission changes. Our case study shows that there is huge potential in extending the IO-based SDA method to other trade-related studies.

Digital Management of Power Transmission and Transformation Works Based on Building Information Model

The application of digital management of power transmission project based on BIM technology is introduced in this paper. In recent years, the vigorous development of China’s power grid, especially the comprehensive construction of UHV power transmission and transformation projects, has provided strong support for China’s power grid construction. With engineering and technical personnel’s gradual dependence on digital information, a 3-D digital management system based on BIM technology has been progressively implemented. It has become an inevitable trend to establish a 3-D digital and integrated platform based on BIM technology to assist owners and operators to jointly manage power transmission and transformation projects. With the wide application of power transmission and transformation entity structure BIM models in the design, construction, procurement, management and operation phases, the advantages of BIM technology in visualization, coordination, simulation and integration continue to emerge in its effective circumventing the risks and hidden dangers of power projects. Thus, BIM technology has gradually become a new channel for enterprises to earn profits and win greater economic benefits and market competitiveness.

Power delivery to a piezoelectric transducer embedded in an elastic body by acoustic waves

ABSTRACTWe studied the transmission of power to a piezoelectric transducer embedded in an elastic body by acoustic waves. A four-layer mechanics model was constructed. A theoretical analysis was performed using the equations of linear piezoelectricity and elasticity. The input admittance, the output voltage and the efficiency of the power transmission structure were calculated. It was shown that significant energy transmission can be produced at a few resonant frequencies. The effects of various physical and geometric parameters were examined. The performance of the structure is sensitive to these parameters and design optimization is necessary for effective power transmission. It was found that the location of the piezoelectric transducer inside the elastic body does not matter much. As long as the strain in the transducer is large and does not change its sign along the transducer thickness, a significant output can be received.

Design and test of 1/5th scale horizontal axis tidal current turbine

Tidal current energy is prominent and renewable. Great progress has been made in the exploitation technology of tidal current energy all over the world in recent years, and the large scale device has become the trend of tidal current turbine (TCT) for its economies. Instead of the similarity to the wind turbine, the tidal turbine has the characteristics of high hydrodynamic efficiency, big thrust, reliable sealing system, tight power transmission structure, etc. In this paper, a 1/5th scale horizontal axis tidal current turbine has been designed, manufactured and tested before the full scale device design. Firstly, the three-blade horizontal axis rotor was designed based on traditional blade element momentum theory and its hydrodynamic performance was predicted in numerical model. Then the power train system and stand-alone electrical control unit of tidal current turbine, whose performances were accessed through the bench test carried out in workshop, were designed and presented. Finally, offshore tests were carried out and the power performance of the rotor was obtained and compared with the published literatures, and the results showed that the power coefficient was satisfactory, which agrees with the theoretical predictions.

트랙터 자동변속기 되먹임 변속 제어기 설계

Nowadays automatic transmission equipped vehicles prevail in construction and agricultural equipment due to their convenience in driving and operation. Though domestic vehicle manufacturers install imported electronic controlled transmissions at present, overseas products will be replaced by domestic ones in the near future owing to development efforts over the past 10 years. For passenger cars, there are many kinds of shift control algorithms that enhance the shift quality such as feedback and learning control. However, since shift control technologies for heavy duty vehicles are not highly developed, it is possible to improve the shift quality with an organized control method. A feedback control algorithm for neutral-into-gear shift, which is enabled during the inertia phase for the master clutch slip speed to track the slip speed reference, is proposed based on the power transmission structure of TH100. The performance of the feedback shift control is verified by a vehicle test which is implemented with firmware embedded TCU. As the master clutch engages along the predetermined speed trajectory, it can be concluded that the shift quality can be managed by a shift time control parameter. By extending the proposed feedback algorithm for neutral-into-gear shift to gear change and shuttle shift, it is expected that the quality of the shift can be improved.

친환경 하이브리드 동력 시스템 개발 및 농기계 응용

A hybrid power system was developed for agricultural machines with a 20kW output capacity, and it was attached to a multi-purpose cultivator to improve the performance of the cultivator. The hybrid system combined heterogeneous sources: an internal-combustion engine and an electric power motor. In addition, a power splitter was developed to simplify the power transmission structure. The cultivator using a hybrid system was designed to have increased fuel efficiency and output power and reduced exhaust gas emissions, while maintaining the functions of existing cultivators. The fuel consumption for driving the cultivator in the hybrid engine vehicle (HEV) mode was 341g/kWh, which was 36% less than the consumption in the engine (ENG) mode for the same load. The maximum power take off output of the hybrid power system was 12.7kW, which was 38% more than the output of the internal-combustion engine. In the HEV mode, harmful exhaust gas emissions were reduced; i.e., CO emissions were reduced by 36~41% and NOx emissions were reduced by 27~51% compared to the corresponding emissions in the ENG mode. The hybrid power system improved the fuel efficiency and reduced exhaust gas emissions in agricultural machinery. The hybrid system’s lower exhaust gas emissions have considerable advantages in closed work environments such as crop production facilities. Therefore, agricultural machinery with less exhaust gas emissions should be commercialized.

Application of Neural Network in Analyzing Torque Coefficient of Hot-Dip Galvanized Fasteners

Hot-dip galvanized fasteners are key connecting components on power transmission towers and structures. In order to improve the installation code of galvanized fasteners, this paper establishes a three-layer (BP) neural network by using the friction coefficients between threads, nut bearing surface friction coefficients and the associated torque coefficients. In addition, the neural network is trained to predict the torque coefficients of fasteners. It can be seen from the research results that the torque coefficients fall within [0.355, 0.709]. Subsequently, the prediction capability of neural network is verified through tests and statistics upon real galvanized fasteners, proving that BP neural network is an effective model.

Environmentally Friendly Hybrid Power System for Cultivators

Purpose: In this study, a hybrid power system was developed for agricultural machines with a 20-KW output capacity, and it was attached to a multi-purpose cultivator to improve the performance of the cultivator, which was evaluated using output tests. Methods: The hybrid system combined heterogeneous sources: an internal-combustion engine and an electric power motor. In addition, a power splitter was developed to simplify the power transmission structure. The cultivator using the hybrid system was designed to have increased fuel efficiency and output power and reduced exhaust gas emissions, while maintaining the functions of existing cultivators. Results: The fuel consumption for driving the cultivator in the hybrid engine vehicle (HEV) mode was 341 g/KWh, which was 36% less than the consumption in the engine (ENG) mode for the same load. The maximum power take off output of the hybrid power system was 12.7 KW, which was 38% more than the output of the internal-combustion engine. In the HEV mode, harmful exhaust gas emissions were reduced; i.e., CO emissions were reduced by 36~41% and NOx emissions were reduced by 27~51% compared to the corresponding emissions in the ENG mode. Conclusions: The hybrid power system improved the fuel efficiency and reduced exhaust gas emissions in agricultural machinery. Lower exhaust gas emissions of the hybr id system have considerable advantages in closed work environments such as crop production facilities; therefore, agricultural machinery with less exhaust gas emissions should be commercialized. However, the high manufacturing cost and complexity of the proposed system are challenges which need to be solved in the future.

Optimización mixta de estructuras de transporte de energía: aplicación del algoritmo de recocido simulado

A general methodology to optimize the weight of power transmission structures is presented in this article. This methodology is based on the simulated annealing algorithm defined by Kirkpatrick in the early ‘80s. This algorithm consists of a stochastic approach that allows to explore and analyze solutions that do not improve the objective function in order to develop a better exploration of the design region and to obtain the global optimum. The proposed algorithm allows to consider the discrete behavior of the sectional variables for each element and the continuous behavior of the general geometry variables. Thus, an optimization methodology that can deal with a mixed optimization problem and includes both continuum and discrete design variables is developed. In addition, it does not require to study all the possible design combinations defined by discrete design variables. The algorithm proposed usually requires to develop a large number of simulations (structural analysis in this case) in practical applications. Thus, the authors have developed first order Taylor expansions and the first order sensitivity analysis involved in order to reduce the CPU time required. Exterior penalty functions have been also included to deal with the design constraints. Thus, the general methodology proposed allows to optimize real power transmission structures in acceptable CPU time.