Power Transmission Loss Research Articles

An LMP forecasting method considering the transmission loss and the correlation among stochastic wind power outputs

The global environmental concern has promoted the installed capacity of renewable energy to explode. The uncertainty of the growing renewable energy poses a risk of incorrect forecasting of clearing prices and misled strategies to participants in the deregulated power markets. However, the transmission loss and the correlation among integrated wind power outputs are ignored in the existing research. To improve the forecasting accuracy, this paper presents a Markov Chain Monte Carlo method for stochastic LMP considering the correlation among wind power outputs and transmission loss. The expectation of an LMP with a given precision can be obtained from the proposed method. The case study verifies the validity of the proposed method, demonstrating that the squared Euclidean distance of the selected Archimedean Copula function is limited to 9.3143. Additionally, given the same convergence criteria, the sampling times are reduced by an order of magnitude compared to the Acceptance-Rejection sampling method.

Design and development of a piezoelectric-hydraulic hybrid actuator with quarter-wavelength tubes

The piezoelectric hydraulic actuator is a hybrid device consisting of a hydraulic pump driven by a piezoelectric stack connected to a hydraulic cylinder. For this type of piezoelectric actuator, the inertial force caused by the flow pulsation of the liquid will inhibit the movement of the piezoelectric vibrator and reduce its output performance. To solve these issues, two tubes were embedded into the piezoelectric-hydraulic hybrid actuation system for the first time to act as mechanical bandstop filters by interfering with the propagation of acoustic waves. The acoustic power transmission loss of the tube is derived from the one-dimensional wave equation. According to the experimental results, when the excitation frequency is close to the optimal operating frequency corresponding to the tubes, the liquid pulsation rate is reduced, the influence of inertial force on the actuator is weakened, and the output performance is relatively significantly improved. This strategy finally leads to a maximum no-load velocity of 153.5 mm s−1 and a maximum blocking force of 261.5 N for the hybrid actuator with 300 mm tubes; the maximum no-load velocity and blocking force of the hybrid actuator with 500 mm tubes are 94.45 mm s−1 and 230 N, respectively. Furthermore, this strategy can be used in other electrohydraulic actuators to enhance their capabilities.

Novel Calculation Method for Windage Power Loss of Double-Helical Gear Transmission

Abstract This paper presents a novel fast calculation method for windage power loss (WPL) of the meshing double-helical gear pair. Firstly, based on the basic equations of fluid mechanics and computational fluid dynamics simulation method, the calculation method for single-tooth windage torque at the zone of meshing/nonmeshing is established; Secondly, the WPL of meshing gear pair with different gear parameters and operating conditions are obtained according to the single-tooth windage torque during a rotation period and the windage torque at the end faces, and the accuracy of the proposed WPL method is verified through the WPL test measurement and simulation; Finally, the effect of gear parameters and operating conditions on the WPL is studied.

Optimal utilization of clean energy and its impact on hybrid power systems incorporating STATCOM and pumped hydro storage

In an attempt to widen the prospects for clean energy utilization and sustainable development, wind and solar power are considered as the prime contributors. But, their volatility is the major constraint in the optimal generation scheduling and power dispatching. Thus, achieving a reliable, techno-economic and voltage secure power system operation with multiple renewable generation facilities becomes a challenging issue. To address these issues, this work presents the combined operation of wind + solar PV + thermal (WPT) system incorporating pumped hydro storage (PHS) facility in a security constrained optimal power flow framework. The impact of PHS in minimizing the dependence on fossil fuel, operating cost and power transmission loss is evaluated in a constrained optimization environment. The complex objective of maintaining a secure voltage during normal and disrupted system operation is addressed by incorporating the static synchronous compensator (STATCOM). Using an intelligent technique, optimal operational paradigm for different hybrid configurations is evaluated. To demonstrate the effectiveness of the proposed hybrid power system, a comparative performance analysis is depicted among three different configurations i.e. WPT, WPT + PHS and WPT + PHS + STATCOM in satisfying several operational objectives. Constraints related to intermittency of renewable power are incorporated to illustrate a real-time analysis. A detailed mathematical modelling of system components and their behaviour is analyzed in MATLAB/SIMULINK platform. The validation of improved results with STATCOM incorporated configuration i.e. (cost savings of 2.59 × 105 US$/y and 10%–16% improvement in system voltage profile) is demonstrated in the IEEE30 bus benchmark power system.

Design and Optimization of High-Gain Bidirectional DC–DC Converter for Electric Vehicles

To better leverage and cope with the characteristics of low-voltage electric vehicle battery pack, this work optimizes the design of on-board bidirectional DC/DC converter. Based on the dual active half-bridge (DAHB) converter, combined with partial switch sharing, a high gain bidirectional DC/DC converter is proposed. This converter has 48-V and 24-V output voltage levels, and the multiple voltage levels, which are often required by new energy vehicles, are able to reduce the number of on-board converters. The theoretical part of this work analyzes the design process of the converter, and in parallel, establishes the mathematical models of transmission power, soft switching, current stress and reactive backflow loss. Under the condition of high gain, the system has good soft switching characteristics and low reactive backflow loss. In the experimental part, a prototype with an input voltage of 400V is built under an operating frequency of 100 kHz. The voltage of the two output ports is stable and a peak efficiency of 94.7% is achieved. The experimental results verify the validity of the theoretical analysis.

Characterization of an airborne organic contaminant sensor based on microfibers with sol–gel film

Introduction: Based on microfibers with sol–gel film, this study focuses on developing an organic contaminant sensing device to monitor airborne organic contamination in high-power laser facilities.Methods: The device heightened the sensitivity to the external environment with the nano-structure of sol–gel on the microfiber surface. The relationship between the additional laser transmission power loss caused by contaminants and the filling rate of the porosity of the film was discussed. In addition, we obtained the relationship between the additional loss and the refractive index of the microstructure.Results: The experimental results indicated that employing microfibers with microstructure coating could significantly improve sensing sensitivity to airborne organic contaminants. The precision of sensing surface contaminants can reach ng/cm2. When the concentration of organic contaminants is lower than 7.5%, the adsorption process of the microstructure coating is dominated by single-molecule adsorption, and the additional loss increases exponentially with increasing concentration, while the sensing limit is 70 ppm. When the concentration of organic contaminants exceeds 7.5%, the adsorption process of the surface microstructure coating is dominated by multimolecular adsorption. Therefore, the additional loss is exponentially related to the concentration of airborne organic contaminants, while the sensing limit is 10 ppm.Discussion: The study explored the adsorption mechanism of the sol–gel film to airborne organic contaminants at different concentrations. The Langmuir monolayer adsorption isotherm model and the Freundlich multi-molecular layer adsorption isotherm model was adopted to analyze and verify the experimental results, which suggested that the experimental results agree well with the simulation results. This work can be considered for in situ monitoring of airborne concentration contaminants and the transmittance of optics with the sol–gel film, and it also provides a new research method for in situ monitoring of airborne organic contaminants in the vacuum environment.

Multi-Objective Optimal Power Flow Incorporating Flexible Alternating Current Transmission Systems: Application of a Wavelet-Oriented Evolutionary Algorithm

This article presents a meta-heuristic hybrid algorithm to solve multi-objective optimal power flow (MOOPF) taking into account multi-fuel constraint. Four different objective functions, which comprise total generation cost, emission, real power transmission losses, and voltage deviation, are simultaneously considered in the proposed MOOPF. Furthermore, two types of flexible alternating current transmission system (FACTS) devices are utilized including thyristor controlled series compensator (TCSC) and unified power flow controller (UPFC). Considering all of the aspects referred to above makes the traditional OPF problem more complicated; hence, it is necessary to approach the problem by a powerful optimization algorithm. Toward this end, this article develops a hybrid algorithm oriented to shuffled frog leaping algorithm (SFLA) and particle swarm optimization (PSO), called hybrid wavelet mutation (WM) based SFLA-wavelet mutation based PSO (HWM2SFLA-PSO). Obtained results validate the effectiveness of the proposed hybrid algorithm in solving different forms of the OPF problem on IEEE test systems compared to those available in the literature. Moreover, the comparison substantiates the superiority of the proposed HWM2SFLA-PSO algorithm in terms of execution time, quality of solution as well as preventing from convergence to local optima, to name but three.

Two-step optimization algorithm for energy management and active-reactive power commands for real-time operation of hybrid microgrids

This paper proposes a two-step optimization algorithm for energy management and optimal control of activereactive power commands in microgrids. The first step ensures an optimal energy management and provides the active power setpoints for power plants and energy storage. The second step calculates the voltage setpoints for power plants and reactive power flows whilst minimizing power transmission losses. This work focuses on the second step of the algorithm and the framework to combine both. A previous study introduces the first step based on a receding-horizon scheme. It is analysed and discussed the performance of the algorithm against two decentralized methods widely used in the literature. The results show that the proposed algorithm reduces power transmission losses by more than 20% compared to other methods.

Superconducting DC power transmission for subway lines that can reduce electric resistance and save energy

Electric railway systems are widely used and DC systems have been employed in a number of metropolitan areas. However, they have some problems, such as cancelled regeneration and energy loss. Introducing superconducting feeder cables into railway feeding systems offers a lot of benefits: fewer substations, equalization of load among substations, reduction of cancelled regeneration, power transmission loss. Feeding systems adopted by railways throughout the world can be classified into feeding systems through overhead trolley wires and ground third rails. These problems are especially serious in third rail system because the voltage is low and the electric current is high. By using a newly developed superconducting feeder system on a third rail system, we conducted a power transmission test. Also, the feeding of the high current and regeneration current was proved to be successful in the course of the train running test on subway line. And, we specifically analyzed the energy generated when a cable was adopted into the third rail line. As a result of adoption of a superconducting feeder cable, the voltage drop specific to railways could be reduced even with a short cable. And, if the cable is adopted in subway line, we also observe large energy-saving effect.

A hybrid estimation of carbon footprints for urban commuting transportation via path reconstruction

The transportation sector is a major source of carbon emissions, and it is of great significance to study the estimation method of carbon emissions from urban commuting traffic for energy conservation and emission reduction. In view of the difficulty of collecting detailed trip trajectory data, this paper first reconstructs the trip paths via an improved modal choice model and a modified path planning model based on the O-D trip matrix, taking seven single traffic modals and two combined modals into account. In order to estimate the carbon footprints with theoretical accuracy, the bottom-up method is adopted considering the trip modal, vehicle type, power source, vehicle occupancy, operation characteristics and traffic conditions. Meanwhile, faced with the converted carbon emissions from electric vehicles, factors like charging efficiency, vehicular load, regional power structure and transmission loss are further considered in the estimation function. A case study of Changzhou City has been performed to verify the feasibility of the proposed models, where the volume distribution of commuting trips is predicted upon a modified network traffic assignment by TransCAD, and the spatial distribution of carbon emission intensity has further expanded to the adjacent areas via ArcMap analysis tools. The total carbon emission and the average link emission intensity of daily commuting in the study area are about 14.7 × 105 kg/day and 870 kg/km respectively. The discussion results indicate that the CO2 emission of fuel-driven vehicles accounts for over 86%, and the equivalent carbon emission of electric vehicles accounts for about 14% under given modal choices. The correlations of carbon emissions to road levels and zone attributes get further revealed and discussed based on the estimation results.

Load Profile and Load Flow Analysis for a Grid System with Electric Vehicles Using a Hybrid Optimization Algorithm

As they become more widespread, electric vehicles (EVs) will require more electricity to charge. It is expected that a range of grid transportation solutions that complement one another and considerable transmission infrastructure changes will be needed to achieve this goal. Strategic planning and control, including economic models and strategies to engage and reward users, can reduce energy loss on the power network. This would eliminate grid upgrades. Bidirectional charging of EVs can help transmission systems cope with EV allocation. Power loss and voltage instability are the transmission network’s biggest issues. Adding EV units to the transmission network usually solves these problems. Therefore, EVs need the right layout and proportions. This study determined where and how many radial transmission network EVs there should be before and after the adjustment. To discover the best EV position and size before and after the dial network modification, a hybrid genetic algorithm for particle swarm optimization (HGAIPSO) was utilized. Electric vehicles coordinated in an active transmission network reduce power losses, raise voltage profiles, and improve system stability. Electric vehicles are responsible for these benefits. The simulation showed that adding EVs to the testing system reduced power waste. The system’s minimum bus voltage likewise increased. The proposed technology reduced transmission system voltage fluctuations and power losses, according to the comparison analysis. The IEEE-30 bus test system reduced real power loss by 40.70%, 36.24%, and 42.94% for the type A, type B, and type C EV allocations, respectively. The IEEE-30 bus voltage reached 1.01 pu.

Theoretical Calculations and Experimental Studies of Power Loss in Dual-Clutch Transmission of Agricultural Tractors

Recent carbon neutrality policies have led to active research in the agricultural tractor sector to replace internal combustion engines, making it imperative to minimize power losses to improve efficiency. Dual-clutch transmissions (DCTs) have been employed in agricultural tractors primarily due to their short shift time and smooth shift feel. However, DCTs have a relatively large number of components and complex structures owing to spatial constraints, making it challenging to predict power losses. Therefore, to predict DCT power losses, this study defined oil churning by considering the structural characteristics and oil circulation and comparing and analyzing the theoretical calculation and test results of power losses at different oil levels. Power loss was calculated based on ISO standards and fluid viscosity theory, and tests were performed to verify. We calculated power losses based on the defined oil churning of a DCT in agricultural tractors and confirmed that their consistency in test results improved when reflecting the lubrication state, considering the structural features and oil circulation. In addition, the factors contributing to power loss under low- and high-speed conditions were analyzed by calculating the power loss for each component.

A new solution approach for non-convex combined heat and power economic dispatch problem considering power loss

The combined heat and power economic dispatch (CHPED) problem is a non-convex multivariate global optimization problem. The objective of the problem is to reduce total production costs while imposing a variety of constraints and meeting the demand for power and heat. Three recently presented metaheuristic approaches, Slime Mould Algorithm (SMA), COOT algorithm and Marine Predators Algorithm (MPA), are applied for solving CHPED problem. Studies dealing with the CHPED problem in the literature often do not consider valve points effect, prohibited operation zones for power-only units, feasible region constraints of combined heat and power units, all at once. Furthermore, power losses are neglected especially in large-scale problems. In this study, the CHPED problem is solved by considering all operational constraints including active power transmission losses. Three separate case studies with dimensions of 11 units, 48 units, and 96 units were used in the tests under various limitations. The experimental results revealed that MPA outperformed not only SMA, and COOT but also the algorithms proposed previously in the literature.

Power losses in natural gas and hydrogen transmission in the Portuguese high-pressure network

Power losses in natural gas and hydrogen transmission in the Portuguese high-pressure network

A Comprehensive Review on Optimal Coordination of Electrical Vehicles to Reduce Power loss

Abstract: This Paper aims to present a report on the study of the various methods of coordinating electrical vehicles in an optimal way so as to reduce the generation cost and the transmission power loss from Grid to load and Also to improve the charging performance of electric vehicles (EV) by various methods like Photo-voltaic(PV) roof mounted panels battery swapping and charging stations (BScSs), Branch Flow model based relaxed optimal power flow (BFM-RoPF), A physical fair Queueing framework, use of switched shunt capacitors(SSCS) etc. By comparing various methods of Coordination of electrical vehicles we can get a better solution to reduce the power loss and to improve the charging performance of electrical vehicles.

분산형 전원이 연결된 배전계통에서의 분리된 상별 인공지능 모델을 이용한 고장종류 및 고장구간 판별 방법

In recent years, the number of distributed generation (DG) in distribution network (DN) has increased. The increasing proportion of DG in DN brings benefits through improved network reliability and reduced transmission power losses. However the connection of DG makes network be more complicated, it changes the unidirectional flow of currents and power to bidirectional flow and thus protection based on over-current relay has limitations of protection coordination. These limitations may occur malfunction or misbehavior of protective devices so it requires new protection methods. This paper proposes a new method using artificial neural network (ANN) can adjust on DN with DG to allocate fault section and to classify fault type as part of solving limitations of protection coordination. This ANN model is separated to each phase and use magnitude and phasor of voltages and currents extracted from each generation sides. The new proposed method is applied to unbalanced distribution network model and verified to be useful in DN through computer simulations.

Lightweight Copper–Carbon Nanotube Core–Shell Composite Fiber for Power Cable Application

The substitution of traditional copper power transmission cables with lightweight copper–carbon nanotube (Cu–CNT) composite fibers is critical for reducing the weight, fuel consumption, and CO2 emissions of automobiles and aircrafts. Such a replacement will also allow for lowering the transmission power loss in copper cables resulting in a decrease in coal and gas consumption, and ultimately diminishing the carbon footprint. In this work, we created a lightweight Cu–CNT composite fiber through a multistep scalable process, including spinning, densification, functionalization, and double-layer copper deposition. The characterization and testing of the fabricated fiber included surface morphology, electrical conductivity, mechanical strength, crystallinity, and ampacity (current density). The electrical conductivity of the resultant composite fiber was measured to be 0.5 × 106 S/m with an ampacity of 0.18 × 105 A/cm2. The copper-coated CNT fibers were 16 times lighter and 2.7 times stronger than copper wire, as they revealed a gravimetric density of 0.4 g/cm3 and a mechanical strength of 0.68 GPa, suggesting a great potential in future applications as lightweight power transmission cables.

Interdependencies in HVDC grid protection: Impact of converter parameters and controls on DC fault‐ride‐through capabilities and protection system design

AbstractFor future multi‐terminal HVDC networks, protection systems based on DC circuit breakers (DCCBs) are envisioned to limit the loss of power transmission towards AC grid(s). Yet, HVDC protection system design is considered a major challenge—especially in a multi‐vendor setup. In particular, protection systems shall enable HVDC converters to ride through DC faults without protective blocking. Several studies have performed sensitivity analyses to determine the DCCB properties and current‐limiting inductor properties that are required to enable converter fault‐ride‐through (FRT), but the HVDC converters themselves have been simplified and kept identical. However, in a multi‐vendor setup, the exact converter design is not known at the time of DC protection planning. Therefore, this paper investigates the impact of different converter properties on the DC‐FRT behaviour, and reveals implications on HVDC protection design. Firstly, analytical approaches are proposed to mathematically derive potential impact factors on the converters’ FRT characteristics, also considering different converter control architectures. Secondly, a comprehensive EMT study demonstrates a significant impact of the converter parameters on the FRT behaviour. Analytical approaches and EMT results are compared with regard to limitations and applicability, such that the paper's findings can support the development of functional requirements for multi‐vendor multi‐terminal HVDC networks.

Improved PSO with Disturbance Term for Solving ORPD Problem in Power Systems

The essential purpose of an energy system is to provide electricity to its loads effectively and economically, as well as safely and reliably. Therefore, the solutions to the problems of Optimal Power Flow (OPF) and Optimal Reactive Power Dispatch (ORPD) to enable the efficient employment of various energy distributions should be found. Our work focuses on the ORPD issue; it can be formulated as a non-linear constraint and with single or multiple objectives optimization problems. Minimizing total losses is one of the main objective functions to solve the ORPD problem. This paper presents the use of an improved particle swarm optimization -with a disturbance term- (called PSO-DT) algorithm, to find the solution of ORPD in the standard IEEE 30-bus power system for reducing electrical power transmission losses. The obtained results demonstrate that the proposed method is more efficient and has a more extraordinary ability to get better solutions compared to the basic PSO method.

Optimization of renewable energy-based transmission system: an application of the genetic, ant colony optimization, Q-learning, and Dijkstra’s algorithms

ABSTRACT Losses in the electrical power transmission and distribution systems are considered two of the most critical challenges in power grids. Reducing the related losses plays a significant role in increasing system efficiency in addition to diminishing costs. Therefore, optimum power transfer as well as finding a convenient route, are essential factors in electrical grids. This paper intends to substantially reduce the transmission/distribution-related losses by finding the shortest and most optimal path between the renewable energy power plant (producer) and the substations/consumers. A genetic algorithm (GA) is proposed for optimal routing to increase the system’s reliability and minimize the losses of the entire network. In this work, by presenting a coding with chromosomes of variable length and considering the construction costs and the power transmission line/path as the fitness function, the appropriate route is obtained. The efficiency of the proposed method is compared with Dijkstra’s algorithm, one of the conventional graph search approaches. The ant colony optimization (ACO) algorithm and a reinforcement learning algorithm, namely the Q-learning model, are employed to further explore the optimization efficiency of the proposed renewable energy-based transmission system. The simulation results demonstrate that the proposed models accurately determine the optimal pathway within an excellent time.