Minimum Transmission Loss Research Articles

Wind Speed Variation Impact on Transmission Loss Reduction in Electricity Market

Abstract In this paper, effect of wind speed variation on its output has been obtained and analysis has been carried out for transmission loss minimization. Mixed integer nonlinear programming (MINLP) approach has been utilized for determining optimal location and number of DFIG as distributed generators considering minimization of transmission loss. The impact of wind speed variation has also been incorporated in the optimization model for obtaining the impact of DFIG output on the transmission loss. The capability curves of DFIG have been modeled in an optimization model and impact of wind speed variation for 24 hrs has been considered to obtain the impact on DFIG output and thereby on the transmission loss. The total real and reactive power loss, optimal DG location, 24 hr optimal schedule of conventional generators and DG output has been obtained. The effect wind variation is determined on the location and output of DG. The proposed MINLP based optimization approach has been applied for IEEE 24 bus reliability test system.

2D MEMS electrostatic cantilever waveguide scanner for potential image display application

This paper presents the current status of our micro-fabricated SU-8 2D electrostatic cantilever waveguide scanner. The current design utilizes a monolithically integrated electrostatic push-pull actuator. A 4.0 μm SU-8 rib waveguide design allows a relatively large core cross section (4μm in height and 20 μm in width) to couple with existing optical fiber and a broad band single mode operation (λ= 0.7μm to 1.3μm) with minimal transmission loss (85% to 87% output transmission efficiency with Gaussian beam profile input). A 2D scanning motion has been successfully demonstrated with two fundamental resonances found at 202 and 536 Hz in vertical and horizontal directions. A 130 μm and 19 μm, corresponding displacement and 0.062 and 0.009 rad field of view were observed at a +150V input. Beam divergence from the waveguide was corrected by a focusing GRIN lens and a 5mm beam diameter is observed at the focal plane. The transmission efficiency is low (~10%) and cantilever is slightly under tensile residual stress due to inherent imperfection in the process and tooling in fabrication. However, 2D light scanning pattern was successfully demonstrated using 1-D push-pull actuation.

Optimal placement of SVC for transmission loss minimisation using self-adaptive firefly algorithm

Transmission loss minimisation is an important research issue, which can be minimised by reactive power compensation. Static var compensator (SVC) is a popular flexible alternating current transmission system (FACTS) device for reactive power support in power system. A new strategy has been proposed for optimal placement of SVC in power systems with a view to minimise the transmission loss. The proposed approach uses a self-adaptive firefly algorithm (SAFA) and identifies the optimal location for SVC placement and their parameters. The SVC placement strategy is applied on IEEE 14, IEEE 30 and IEEE 57-bus systems and their results are presented to demonstrate its effectiveness.

Operación económica de dispositivos almacenadores de energía para disminución de pérdidas

Este artículo presenta un algoritmo para la ope­ración óptima de unidades de almacenamiento de energía (UDAE), desde la perspectiva de las pérdidas de potencia activa. Se propone un mode­lo exacto basado en relajación lagrangeana. Los resultados de simulación sobre el alimentador de distribución IEEE de 37 nodos demuestran que un sistema de almacenamiento de energía puede ser utilizado para minimizar las pérdidas en un sis­tema de distribución, a través de la modificación de la curva de carga. La principal contribución de este enfoque consiste en el tratamiento de la función objetivo y el algoritmo de optimización. Los multiplicadores de Lagrange son usados para determinar la ubicación y el dimensionamiento óptimo de las unidades de almacenamiento. Se presenta además una discusión sobre el impacto de las UDAE en el planeamiento de la red de dis­tribución.

Power Control of Microgrid with Rich Small Hydropower Stations

In China, some remote areas with rich small hydropower stations suffer from a tradeoff between water surplus and off-limit voltage in the grid during wet seasons. The microgrid of new energy sources provides a new way of solving this problem. Under the background of the microgrid proposed in somewhere of Jiangxi Province, this paper firstly carries out simplified model on the actual system. Output models of PV and small hydropower stations are established. Then with Minimizing transmission losses of microgrid system and the amount of all small hydropower abandoned waters as the optimization objective, and considering the output constraints of each micro power source, power balance constraints and voltage constraints. A micro-power output optimization model is established and then solved by improved particle swarm optimization algorithm. By comparing the micro-power output and system line loss before and after the optimization, it verifies that the proposed power control method can prevent the off-limit voltage effectively and reduce transmission losses of the system.

Solution of multi-objective optimal reactive power dispatch using pareto optimality particle swarm optimization method

For Multi-Objective Optimal Reactive Power Dispatch (MORPD), a new approach is proposed as a simultaneous minimization of the active power transmission loss, the bus voltage deviation and the voltage stability index of a power system are obtained. Optimal settings of continuous and discrete control variables (e.g., generator voltages, tap positions of tap changing transformers and the number of shunt reactive compensation devices to be switched) are determined. MORPD is solved using Particle Swarm Optimization (PSO). Also, Pareto Optimality PSO (POPSO) is proposed to improve the performance of the multi-objective optimization task defined with competing and non-commensurable objectives. The decision maker requires to manage a representative Pareto-optimal set provided by imposition of a hierarchical clustering algorithm. The proposed approach was tested using IEEE 30-bus and IEEE 118-bus test systems. When simulation results are compared with several commonly used algorithms, they indicate better performance and good potential for their efficient applications in solving MORPD problems.

UPFC with series and shunt FACTS controllers for the economic operation of a power system

This paper presents the application of Genetic Algorithm (GA) and Differential Evolution (DE) technique for the minimization of transmission loss and simultaneous reduction in the operating cost of the system using Flexible AC Transmission System (FACTS) devices. Three types of FACTS devices, Thyristor Controlled Series Compensator (TCSC), Static VAR Compensator (SVC) and Unified Power Flow Controller (UPFC) are considered for this purpose. Optimal placement of FACTS devices in the heavily loaded power system reduces transmission loss, control reactive power flow, improves voltage profile of all nodes and also reduces operating cost. The system is reactively loaded starting from base to 200% of base reactive load and the system performance is observed without and with FACTS devices. The proposed technique is applied on IEEE 30-bus system for the optimal setting of FACTS devices. Finally, how system performance is improved with the use of UPFC along with other series and shunt FACTS controller is illustrated.

Multi-objective optimal power flow using quasi-oppositional teaching learning based optimization

This paper describes teaching learning based optimization (TLBO) algorithm to solve multi-objective optimal power flow (MOOPF) problems while satisfying various operational constraints. To improve the convergence speed and quality of solution, quasi-oppositional based learning (QOBL) is incorporated in original TLBO algorithm. The proposed quasi-oppositional teaching learning based optimization (QOTLBO) approach is implemented on IEEE 30-bus system, Indian utility 62-bus system and IEEE 118-bus system to solve four different single objectives, namely fuel cost minimization, system power loss minimization and voltage stability index minimization and emission minimization; three bi-objectives optimization namely minimization of fuel cost and transmission loss; minimization of fuel cost and L-index and minimization of fuel cost and emission and one tri-objective optimization namely fuel cost, minimization of transmission losses and improvement of voltage stability simultaneously. In this article, the results obtained using the QOTLBO algorithm, is comparable with those of TLBO and other algorithms reported in the literature. The numerical results demonstrate the capabilities of the proposed approach to generate true and well-distributed Pareto optimal non-dominated solutions of the multi-objective OPF problem. The simulation results also show that the proposed approach produces better quality of the individual as well as compromising solutions than other algorithms.

Optimal Design of a Helmholtz Resonator With a Flexible End Plate

This paper describes a design process that produces a small volume Helmholtz resonator capable of achieving high transmission loss across a desired frequency range. A multiobjective optimization formulation was used to design a Helmholtz resonator with a flexible end plate. The optimization formulation generated a Pareto curve of design solutions that quantify the trade-off between the optimization goals: minimum resonator volume and maximum transmission loss across a specified frequency range. The optimization problem was formulated and solved in the following manner. First, a mathematical formulation for the transmission loss of the Helmholtz resonator with a flexible plate was completed based on the resonator design parameters. Then, the weighted transmission loss across a specified frequency range and a minimum resonator volume were defined as optimization objectives. Finally, the Pareto curve of optimum design solutions was calculated using a gradient-based approach via the ɛ-constraint method. The optimization results allow the designer to select resonator design parameters that meet the requirements for both transmission loss and resonator volume. To validate the optimization results, two optimal Helmholtz resonators were manufactured and experimentally confirmed.

Artificial Neural Network for Short-Term Load Forecasting in Distribution Systems

The new paradigms and latest developments in the Electrical Grid are based on the introduction of distributed intelligence at several stages of its physical layer, giving birth to concepts such as Smart Grids, Virtual Power Plants, microgrids, Smart Buildings and Smart Environments. Distributed Generation (DG) is a philosophy in which energy is no longer produced exclusively in huge centralized plants, but also in smaller premises which take advantage of local conditions in order to minimize transmission losses and optimize production and consumption. This represents a new opportunity for renewable energy, because small elements such as solar panels and wind turbines are expected to be scattered along the grid, feeding local installations or selling energy to the grid depending on their local generation/consumption conditions. The introduction of these highly dynamic elements will lead to a substantial change in the curves of demanded energy. The aim of this paper is to apply Short-Term Load Forecasting (STLF) in microgrid environments with curves and similar behaviours, using two different data sets: the first one packing electricity consumption information during four years and six months in a microgrid along with calendar data, while the second one will be just four months of the previous parameters along with the solar radiation from the site. For the first set of data different STLF models will be discussed, studying the effect of each variable, in order to identify the best one. That model will be employed with the second set of data, in order to make a comparison with a new model that takes into account the solar radiation, since the photovoltaic installations of the microgrid will cause the power demand to fluctuate depending on the solar radiation.

SWING, VOLTAGE STABILITY AND POWER TRANSFER CAPABILITY IN TRANSMISSION SYSTEM WITH UPFC: THE ART OF STATUS

In modern era, the increasing size of the power sys tem, to maximize the use of existing systems and to provide adequate voltage support is an emphasis on finding solutions. This f lexibility is needed electricity. Better placed than the Flexible AC Transmission Systems (FACTS) to control the flow of electricity, and to provide voltage support can be effective in turn resulting in less damage. The impact of these tools on line flow and bus volt age profile at random algorithm to determine the op timal number of ratings have been studied by keeping them better . The FACTS devices are expensive cause of that FACTS type, number and location of the FACTS devices is very important, for decide the optimal location and parameters of FACTS device s. FACTS are used in the following purposes: Transm ission pricing issues by maximizing social welfare with or without considera tion of FACTS’ costs; Better utilization of FACT by maximizing FACTS devices total transferred power; Reactive power or voltage control by minimizing transmission losses, or volta ge fluctuation. Increase system’s security under emergency by minimizing tra nsmission lines loadability. Power flow control, a current long transmission lin e, plays an important role within the energy system . The letter swings, longdistance transmission line voltage and power flow c ontrol in unified power flow controller (UPFC) base d compensation associated series or shunt FACTS devices are employed. Device s such as the proposed transmission line, between tof the sending and receiving end to the transmission line is used in p laces as different. Here also deals with determini ng the optimum placement of Flexible AC Transmission Systems (FACTS) damping ou t swings, voltage and improves power transfer devic es for a long transmission line. Here the concept of compensation mid-point o f facts is presented for optimal placement.

ENHANCED MULTI-OBJECTIVE PARTICLE SWARM OPTIMIZATION FOR OPTIMAL REACTIVE POWER DISPATCH CONSIDERING VOLTAGE STABILITY

This paper proposed a novel enhanced multi-objective particle swarm optimization (EMOPSO) for solving the optimal reactive power dispatch (ORPD) problem, which minimizes transmission loss while enhancing voltage stability.

LOSS ALLOCATION OF TRANSMISSION LINE AND MINIMIZATION OF LOSS FOR 5 BUS,14 BUS &30 BUS SYSTEMS

The paper focuses on the issue of transmission loss allocation and transmission loss minimization by incorporating UPFC injection model using load flow analysis. To investigate the effect of the UPFC on the steady state condition of the system and load flow, different models can be used. These models are usually based on modification of traditional load flow methods. In this project, a mathematical model for UPFC referred as UPFC injection model is used. Since accurate power tracing is very difficult, allocation of losses for a particular transaction (in power business it is buying and selling system) may not be effectively realized. However loss allocation is an important aspect in determining the cost of transmission. Thus a methodology to find the losses accurately is vital. It is imperative to make sure that all users of the transmission network are charged proportionate to their usage and this aspect is all the more important because of the common infrastructure they use. The Z-bus loss allocation method is used to achieve the required objective. This method will promote more efficient network operations when implemented in deregulated electric industries. The Unified Power Flow Controller (UPFC) injection model is incorporated in Load Flow Model by the method of Newton Raphson Algorithm to study its effects for power flow control and losses minimization in the power system. In this project optimal placement of UPFC is conducted based on active power loss Sensitivity factors. Based on these sensitivity factors the UPFC is optimally placed in the required transmission line to investigate the impact of UPFC in the system. The changes in the system are studied to see the impact of the UPFC. The impact of UPFC are analyzed by using 5-Bus, IEEE.

New Optical Designs for Large Parabolic Troughs

The potential for cost reduction in parabolic troughs (PT) large collector fields is real and will be achieved in a variety of different ways. One problem certainly contributing to the costs of Solar Thermal Electricity (STE) PT fields is certainly the fact that large fields have a significant quantity of receiver lines and pipes bringing the heat transfer fluid to and off from them. The very large pipe length in large collector fields (for instance the 50MW fields in Spain) is a source of heat losses and parasitic losses due to significant pumping power, but also a source of other costs related to the number of pumps, to the amount of (costly) circulating fluid etc. In any given large field, receiver length and pipe length are determined by the aperture size of the PTs and one way to reduce these impacts on cost would be to increase aperture size. This has been the idea behind developments like the Ultimate Trough. In this paper new optical solutions are presented to obtain much larger troughs, using the same “standard” evacuated 70mm inner radius tube, which in fact amounts to a substantial increase of concentration, but without sacrificing the acceptance angle of the optic. The Simultaneous Multiple Surface (SMS) method is used and practical solutions are obtained for apertures nearly close to twice the present standard of ≈ 6m width. The case of troughs for fixed receiver tubes is also discussed in this context. The solutions developed minimize transmission losses due to the glass cover and in that sense are an improvement on previous work. They also achieve a higher optical performance than other second stage solutions, because they are designed to eliminate optical losses through large gaps, something that is associated with the fact that the outer glass envelope has a much larger diameter than the inner receiver tube. The paper presents new examples of larger troughs with second stage concentrators, characterizing and comparing them with a “conventional” PT. The comparison is done for optical properties and for the energy collected on a sunny location (Faro, Portugal). The paper ends with a similar exercise done for fixed receiver troughs, an exercise that also leads to larger troughs (since it is done for the same 70mm inner (evacuated) receiver tube) and concentration is increased. Again optical properties and energy performance are presented and compared with the conventional PT. The new solutions represent a potential reduction in field costs or even in O&M, as suggested, and this exercise will enable manufacturers the pondering of the manufacture of larger troughs (perhaps cheaper on a sqm basis) but with the extra cost of a secondary concentrator, knowing how much energy to expect from the adoption of solutions that benefit non-imaging optics design methods.

Properties and Printability of Inkjet and Screen-Printed Silver Patterns for RFID Antennas

We report the modeling, and geometrical and electrical characterization, of inkjet and screen-printed patterns on different polymeric substrates for use as antennas in radio-frequency identification (RFID) applications. We compared the physical and electrical characteristics of two silver nanoparticle-based commercial inkjet-printable inks and one screen-printable silver paste, when deposited on polyimide (PI), polyethylene terephthalate (PET), and polyetherimide (PEI) substrates. First, the thickness of the inkjet-printed patterns was predicted by use of an analytical model based on printing conditions and ink composition. The predicted thickness was confirmed experimentally, and geometrical characterization of the lines was completed by measuring the root-mean-square roughness of the patterns. Second, direct-current electrical characterization was performed to identify the printing conditions yielding the lowest resistivity and sheet resistance. The minimum resistivity for the inkjet-printing method was 8.6 ± 0.8 μΩ cm, obtained by printing four stacked layers of one of the commercial inks on PEI, whereas minimum resistivity of 44 ± 7 μΩ cm and 39 ± 4 μΩ cm were obtained for a single layer of screen-printed ink on polyimide (PI) with 140 threads/cm mesh and 90 threads/cm mesh, respectively. In every case, these minimum values of resistivity were obtained for the largest tested thickness. Coplanar waveguide transmission lines were then designed and characterized to analyze the radio-frequency (RF) performance of the printed patterns; minimum transmission losses of 0.0022 ± 0.0012 dB/mm and 0.0016 ± 0.0012 dB/mm measured at 13.56 MHz, in the high-frequency (HF) band, were achieved by inkjet printing on PEI and screen printing on PI, respectively. At 868 MHz, in the ultra-high-frequency band, the minimum values of transmission loss were 0.0130 ± 0.0014 dB/mm for inkjet printing on PEI and 0.0100 ± 0.0014 dB/mm for screen printing on PI. Although the resistivity achieved is lower for inkjet printing than for screen printing, RF losses for inkjetted patterns were larger than for screen-printed patterns, because thicker layers were obtained by screen printing. Finally, several coil inductors for the HF band were also fabricated by use of both printing techniques, and were used as antennas for semi-passive smart RFID tags on plastic foil capable of measuring temperature and humidity.

Electromagnetic transmission characteristics of composite frequency selective surfaces coated with conductive polymer–silver paste

Abstract In this work, a kind of conductive polymer–silver paste was used to fabricate composite frequency selective surfaces (FSSs) with four-legged slot elements. Screen printing and 3D engraving process were carried out to coat the conductive polymer–silver paste onto the fabric preform and sculpt composite panels into composite FSSs, respectively. The substrates of the composite FSS were carbon and quartz glass fabrics, respectively. The equivalent electrical conductivity of the composite material FSS was measured and the results showed that it increased significantly after the fabrics printed by the conductive silver paste. Free space method was adopted to test the electromagnetic transmission characteristics of the composite FSS. Experimental results showed that the conductive silver paste was effective to decrease the minimum transmission loss of the composite FSS and the minimum transmission loss of the quartz glass fabric composite FSS was lower than that of the carbon ones. A finite element model was put forward to calculate the electromagnetic transmission characteristics of the composite FSS. The calculated results were in agreement with the experimental data. Effects of the equivalent electrical conductivity and the thickness of the composite substrate on the minimum transmission loss of the carbon fabric composite FSS were investigated.

Solution of reactive power dispatch of power systems by an opposition-based gravitational search algorithm

Gravitational search algorithm (GSA) is based on law of gravity and the interaction between masses. In GSA, searcher agents are collection of masses and their interactions are based on Newtonian laws of gravity and motion. In this paper, to further improve the optimization performance of GSA, opposition-based learning is employed in opposition-based gravitational search algorithm (OGSA) for population initialization and also for generation jumping. In the present work, OGSA is applied for the solution of optimal reactive power dispatch (ORPD) of power systems. Traditionally, ORPD is defined as the minimization of active power transmission losses by controlling a number of control variables. ORPD is formulated as a non-linear constrained optimization problem with continuous and discrete variables. In this work, OGSA is used to find the settings of control variables such as generator voltages, tap positions of tap changing transformers and amount of reactive compensation to optimize certain objectives. The study is implemented on IEEE 30-, 57- and 118-bus test power systems with different objectives that reflect minimization of either active power loss or that of total voltage deviation or improvement of voltage stability index. The obtained results are compared to those yielded by the other evolutionary optimization techniques surfaced in the recent state-of-the-art literature including basic GSA. The results presented in this paper demonstrate the potential of the proposed approach and show its effectiveness and robustness for solving ORPD problems of power systems.

Finite element simulations of low-mass readout cables for the CBM Silicon Tracking System using RAPHAEL

The first three-dimensional simulation study of thin multi-line readout cables using finite element simulation tool RAPHAEL is being reported. The application is the Silicon Tracking System (STS) of the fixed-target heavy-ion experiment Compressed Baryonic Matter (CBM), under design at the forthcoming accelerator center FAIR in Germany. RAPHAEL has been used to design low-mass analog readout cables with minimum possible Equivalent Noise Charge (ENC). Various trace geometries and trace materials have been explored in detail for this optimization study. These cables will bridge the distance between the microstrip detectors and the signal processing electronics placed at the periphery of the silicon tracking stations. SPICE modeling has been implemented in Sentaurus Device to study the transmission loss (dB loss) in cables and simulation has been validated with measurements. An optimized design having minimum possible ENC, material budget and transmission loss for the readout cables has been proposed.

The use of cutting carbon fiber fabric/epoxy composites as band-pass frequency selective surfaces

Sandwich structures with frequency selective surfaces have been widely used to fabricate low-observable radomes. Traditional frequency selective surfaces were made of metals, such as copper and aluminum. There were problems when used the frequency selective surfaces with the sandwich structures, such as a bonding layer and thermal mismatch. Because of the thermal mismatch between the sandwich structures and the metals, mechanical properties of the sandwich structures usually decreased. To avoid these disadvantages, a new type of composite frequency selective surface was put forward in this study. A four-legged slot-array frequency selective surface and a square-aperture array frequency selective surface were fabricated by cutting carbon fiber/epoxy composites. Free-space method and finite-element method were carried out to evaluate the electromagnetic transmission characteristics of the frequency selective surface specimens, respectively. Results show that the composite frequency selective surface with four-legged slot array can realize the function of frequency selection, and its minimum transmission loss can be decreased by increasing the electrical conductivities of the composite material, adjusting the thickness, and increasing the aperture-to-cell ratio of it. For the composite frequency selective surface with square-aperture array, grating lobes come closely after its resonant frequency, although its minimum transmission loss is very close to zero.

Minimization of Transmission Loss in Meshed AC/DC Grids With VSC-MTDC Networks

The paper considers the optimal power flow (OPF) of a meshed AC/DC power transmission network with voltage source converter based multi-terminal DC (VSC-MTDC) networks. The OPF problem is formulated to minimize the transmission loss of the whole AC/DC network with two different VSC control strategies considered, constant DC voltage control (master-slave control) and DC voltage droop control. In addition, Grid Code compliance of wind farms is also embedded in the OPF formulation. The presented OPF is evaluated and demonstrated in the paper by two example meshed AC/DC power systems.