Decrease Power Loss Research Articles

Selection of Sensitive Buses using the Firefly Algorithm for Optimal Multiple Types of Distributed Generations Allocation

Power loss is one aspect of an electric power system performance indicator. Loss of power can have an impact on poor voltage performance at the receiving end. DG integration in the network has become one of the more powerful methods. To get the maximum benefit from synchronizing the system with DG, it is necessary to ascertain the size, location, and type of DG. This study aims to determine the capacity and location of DG connections for DG type I and type II. To address the aim of this paper, a metaheuristic solution based on a firefly algorithm is used. FA can cover up the lack of metaheuristic algorithms that require a long computational time. To ensure that the load bus location solution is selected as the best DG connection location, the input of the load bus candidate has been filtered based on stability sensitivity. The proposed method is tested on IEEE 30 buses. The optimization results show a decrease in power loss and an increase in bus voltage, which affects an increase in system stability by integrating three DG units. FA validation of the evolution-based algorithm shows a significant reduction in computational time.

Включение на параллельную работу объединения северной и южной частей энергосистемы Томской области

The article analyzes possible means for switching the Tomsk electric power system northern and southern parts for parallel operation. This system has the operational separation over the 220 kV power line, which connects the 500 kV Tomsk substation with the Nizhnevartovsk district power plant. With these parts switched for parallel operation, it will be possible to achieve an enhanced level of operational reliability and more efficient power supply, especially in the course of making routine switching operations without the need to disconnect the consumers. This will also make it possible to secure more flexible and stable operation of the power system and to decrease power losses. In view of these considerations, it is important to analyze the possibility of using various means, with applying the synchronism monitoring function, which implies closing of the circuit breaker by synchronization or waiting for synchronism, or using a more advanced system like a back-to-back HVDC link. To this end, the ranges of voltage vector deviation angles between the united substation buses were determined, as well as limiting switching angles at different substations of this 220 kVpower transmission, at which steady-state and transient stability will not be lost. The article presents the results of modeling the operations for switching the power system parts for parallel operation by means of a back-to-back HVDC link. Simulation of the processes triggered in the considered 220 kV power transmission by a short-circuit fault shows the effectiveness of using this device for solving the stated problem. The requirements for determining the back-to-back HVDC link power capacity are specified, and the optimal places for installing it in the considered power transmission line are defined.

OPTIMASI TITIK INTERKONEKSI DISTRIBUTED GENER-ATION (PLTM MUARA) GUNA MEMINIMALKAN RUGI – RUGI DAYA MENGGUNAKAN METODE ARTIFICIAL BEE COLONY (ABC) PADA PENYULANG PANJI

Distributed Generation (DG) is a small power plant that can increase realibility, voltage profil, and reduce power losses in distribution network. DG interconnection locations that are less suitable can in/crease power losses. A possibility that can be done to reduce these power losses is by optimizing DG interconnection points. Optimization of the DG interconnection points on the feeder of Panji aims to minimize power losses, where the initial power losses occur at 48.2 kW. Optimization technique is using the Artificial Bee Colony (ABC) method with losses after simulation at 32.263 kW. When compared with the conditions before and after optimization there is a differ-ence in power losses of 16.035 kW, to a decrease in power losses of 33.2% from the previous loss.

The influence of phase load asymmetry on power losses in power distribution network lines of oil and gas enterprises

The influence of phase load asymmetry on power losses in electric lines is investigated. The influence of phase load redistribution on power losses in three-phase three-conductor line with the insulated neutral is analyzed. It is demonstrated that additional power losses occur in this line which are in quadratic dependency on the relative change of phase loads. The influence of neutral conductor resistance in the four-conductor three-phase electric network on power losses in different asymmetry modes is investigated. It is shown that power losses in this network are much larger than in three-conductor network with identical phase load asymmetry and depend on the neutral conductor resistance. Significant economic effect can be obtained by increasing the cross-section of neutral conductor. At the same time, the simultaneous decrease of power losses and increase of the operational reliability of electric network are observed.

Voltage quality in delta Egypt network and its impact in oil industry

The electrical energy is transmitted from the generating stations to the consumers through a transmission network. The effectiveness of improving voltage profile yields high transmission network efficiency and increase the capacity of transmission lines, also decrease power losses, voltage drop and unplanned shut down in the big industrial and strategic loads like (oil refining industry). This paper objective presents the suggested solutions for improving voltage profile in electrical network of delta Egypt to achieve a voltage quality. The methodology of suggested solutions are applied on delta Egypt network with voltage levels (66, 11, 6.6, 0.4) kV, the simulations were performed using digital simulation and electrical network calculation (DIgSILENT power factory software) to study the voltage profile. The validation of results was performed by comparing the voltage profile of proposed four different scenarios: 1st: power flow in normal operation (without using any voltage improving devices), 2nd: using Automatic Tap Changer (ATC) of transformers, 3rd: installing a Static Volt Ampere Reactive (VAR) System(SVS) with (ATC), 4th: installing a (SVS), (ATC) and shunt reactive power compensation devices (parallel capacitor / inductor). The best voltage profile achieved by using scenario 4, which supported and improved the voltage profile of all system and brings the magnitudes of all buses in permissible voltage level from (0.79-0.99 P.U.) at normal operation (scenario 1) to (0.9-1.04 P.U.) at (scenario 4). So the system can be operated with more efficiently, stability and improving the capacity of the network after applying the solution stated in scenario 4. • This paper studied the voltage profile in delta Egypt network. • A relation between voltage quality and catastrophic events in oil refining industry. • High quality grid must have voltage stability with in accepted levels at each bus. • Network construction was performed by (DIgSILENT power factory software). • The voltage profile was performed by proposed four different scenarios. Scenario 1: power flow (PF) study in normal operation (base case). Scenario 2: (PF) study using automatic tap changer (ATC). Scenario 3: (PF) study using (ATC)& static Var system (SVS). Scenario 4: (PF) study using (ATC), (SVS) and shunt reactive power control devices. • A comparison between all scenarios results have done to get the optimum solution. • The best voltage profile had achieved by using scenario 4.

Optimal location of a single distributed generation unit in power systems

Generally, electrical power distribution networks are considered to be a significant part of the energy supply chain. The main concept behind distributed generation (DG) units is based on the use of small electrical power plants that are directly connected to the electric system near to customers. The reduction of power losses this engenders can decrease the electric power that flows into distribution system feeders, leading to positive impacts on voltage stability, voltage profile, and the capacity of the electrical network. Additionally, from the perspective of utility, DG units allocated near to loads can dramatically decrease power losses in electrical distribution networks. However, DG units must be allocated optimally and correctly to avoid adverse results on electric networks in terms of voltage profiles and power losses throughout the whole network. Thus, this paper presents a simple way to determine optimal location for DG units in both mesh and radial systems by using conventional iterative methods, with the aim of reducing the overall electrical power losses and enhancing the voltage of the network. Both the Newton-Raphson method and a backward and forward method were implemented in a MATLAB environment to solve the optimization problem in an IEEE 14 bus meshed system and an IEEE 33 bus radial system.

Optimal Allocation of DSTATCOM in Distribution Network Using Whale Optimization Algorithm

This paper deals with a new approach implemented to decrease power losses and improve voltage profile in distribution networks using Distribution STATic COMpensator (DSTATCOM). DSTATCOM location can be determined by the voltage stability index (VSI) and sizing can be identified by nature inspired, recently developed whale optimization algorithm (WOA). To check efficacy, the proposed technique is tested on two standard buses: Indian rural electrification 28-bus and IEEE 69-bus distribution systems. Obtained results show that optimal allocation of DSTATCOM effectively reduces power losses and improves voltage profile.

Rotor Damped Natural Frequencies and Stability Under Reduced Oil Supply Flow Rates to Tilting-Pad Journal Bearings

Reduced oil supply flow rates in fluid film bearings can cause cavitation, or lack of a fully developed film layer, over one or more of the pads due to starvation. Reduced oil flow has the well-documented effects of higher bearing operating temperatures and decreased power losses; however, little experimental data are available on its effects on system stability and dynamic performance. The study looks at the effects of oil supply flow rate on dynamic bearing performance by comparing experimentally identified damped natural frequencies and damping ratios to predictive models. A test rig consisting of a flexible rotor and supported by two tilting pad bearings in flooded housings is utilized in this study. Tests are conducted over a range of supercritical operating speeds and bearing loads while systematically reducing the oil supply flow rates provided to the bearings. Shaft response measured as a magnetic actuator is used to perform sine sweep excitations of the rotor. A single-input, multiple-output system identification technique is then used to obtain frequency response functions (FRFs) and modal parameters. All experimental results are compared to predicted results obtained from bearing models based on thermoelastohydrodynamic (TEHD) lubrication theory. Both flooded and starved model flow assumptions are considered and compared to the data. Differences in the predicted trends of the models and the experimental data across varying operating conditions are examined. Predicted pressure profiles and dynamic coefficients from the models are presented to help explain any differences in trends.

Subsynchronous Vibration Patterns Under Reduced Oil Supply Flow Rates

Reduced oil supply flow rates in fluid film bearings can cause cavitation, or lack of a fully developed hydrodynamic film layer, at the leading edge of the bearing pads. Reduced oil flow has the well-documented effects of higher bearing operating temperatures and decreased power losses; however, little experimental data of its effects on system stability and performance can be found in the literature. This study looks at overall system performance through observed subsynchronous vibration (SSV) patterns of a test rig operating under reduced oil supply flow rates. The test rig was designed to be dynamically similar to a high-speed industrial compressor. It consists of a flexible rotor supported by two tilting pad bearings in vintage, flooded bearing housings. Tests were conducted over a number of supercritical operating speeds and bearing loads, while systematically reducing the oil supply flow rates provided to the bearings. A low amplitude, broadband SSV pattern was observed in the frequency domain. During supercritical operation, a distinctive subsynchronous peak emerged from the broadband pattern at approximately half of the running speed and at the first bending mode of the shaft. Under lightly loaded conditions, the amplitude of the subsynchronous peak increased dramatically with decreasing oil supply flow rate and increasing operating speed. Under an increased load condition, the subsynchronous peak was largely attenuated. A discussion on the possible sources of this SSV including self-excited instability and pad flutter forced vibration is provided with supporting evidence from thermoelastohydrodynamic (TEHD) bearing modeling results.

Steady-State Tilting-Pad Bearing Performance Under Reduced Oil Supply Flow Rates

Reduced oil supply flow rates in fluid film bearings can cause cavitation, or lack of a fully developed hydrodynamic film layer, at the leading edge of the bearing pads. Reduced oil flow has the well-documented effects of higher bearing operating temperatures and decreased power losses and is commonly referred to as starvation. This study looks at the effects of oil supply flow rate on steady-state bearing performance and provides increased experimental data for comparison to computational predictions. Tests are conducted on a five-pad tilting-pad bearing positioned in a vintage, flooded housing with oil supply nozzles. Pad temperatures, sump temperature, journal operating position, and motor input power are measured at various operating speeds ranging from 2000 to 12,000 rpm and various oil supply flow rates. Predicted results are obtained from bearing modeling software based on thermoelastohydrodynamic (TEHD) lubrication theory. A starved flow model was previously developed as an improvement over the original flooded flow model to more accurately capture bearing behavior under reduced flow conditions. Experimental results are compared to both flow models. The starved bearing model predicts significantly higher journal operating positions than the flooded model and shows good correlation with the experimental data. Predicted pressure profiles from the starved bearing model show cavitation of the upper unloaded pads that increase in severity with increasing speed and decreasing oil supply flow rate. The progressive unloading of these top pads explains the rise in shaft centerline position and helps further validate the starvation model.

Arcing time analysis of liquid nitrogen with respect to electrode materials

Unlike sulphur hexafluoride (SF6), liquid nitrogen (LN2) is cost effective, environment friendly and cryogenic dielectric. It has astounding insulating properties with the potential to decrease power loss in switchgear applications due to its remarkably low temperatures. The basic research is however a necessity to observe the performance of LN2 subjected to high luminance arcs. So far, there are no findings that refer to the arcing time inside the LN2 environment. The objective of this work was to investigate the arcing times in LN2 and compare the results with open air conditions using different electrode materials.Experiments were conducted on different DC voltages and their arcing times were measured. Three different kinds of electrode materials, namely: pure copper (Cu), stainless used steel (SUS) and aluminium alloy (Al 6061) were tested under 1 atmospheric pressure.The results revealed that LN2 extinguishes arc in almost half the amount of time required by the open air insulation. With Al 6061 has the shortest arcing time, whilst Cu, the second best choice and SUS places last in the evaluation. It was encapsulated from the findings that LN2 is a better choice than air insulation in terms of arc quenching and a better alternative to SF6 when environment is the priority.

Optimization Placement of Static Var Compensator (Svc) on Electrical Transmission System 150 kV Based on Smart Computation

To improve voltage profile, we can use FACTS equipment. One of them is SVC (Static Var Compensator). This study aims to determine the location and optimal capacity of SVC and to determine the effect after SVC installation. This research was conducted in 150 kV transmission system, West Java load regulator area of South Bandung and New Ujungberung subsystem. The research method used for power flow simulation is Newton Raphson and to determine the optimal position and capacity of SVC was using genetic algorithm in MATLAB R2014. After the SVC placement is optimized, then the system performance will increase such as the voltage of all buses is at the standard level and the decrease of power losses.

Effect of distributed generation installation on power loss using genetic algorithm method

Injection of the generator distributed in the distribution network can affect the power system significantly. The effect that occurs depends on the allocation of DG on each part of the distribution network. Implementation of this approach has been made to the IEEE 30 bus standard and shows the optimum location and size of the DG which shows a decrease in power losses in the system. This paper aims to show the impact of distributed generation on the distribution system losses. The main purpose of installing DG on a distribution system is to reduce power losses on the power system.Some problems in power systems that can be solved with the installation of DG, one of which will be explored in the use of DG in this study is to reduce the power loss in the transmission line. Simulation results from case studies on the IEEE 30 bus standard system show that the system power loss decreased from 5.7781 MW to 1,5757 MW or just 27,27%. The simulated DG is injected to the bus with the lowest voltage drop on the bus number 8.

Series-Connected High Frequency Converters in a DC Microgrid System for DC Light Rail Transit

This paper studies and presents a series-connected high frequency DC/DC converter connected to a DC microgrid system to provide auxiliary power for lighting, control and communication in a DC light rail vehicle. Three converters with low voltage and current stresses of power devices are series-connected with single transformers to convert a high voltage input to a low voltage output for a DC light rail vehicle. Thus, Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) with a low voltage rating and a turn-on resistance are adopted in the proposed circuit topology in order to decrease power losses on power switches and copper losses on transformer windings. A duty cycle control with an asymmetric pulse-width modulation is adopted to control the output voltage at the desired voltage level. It is also adopted to reduce switching losses on MOSFETs due to the resonant behavior from a leakage inductor of an isolated transformer and output capacitor of MOSFETs at the turn-on instant. The feasibility and effectiveness of the proposed circuit have been verified by a laboratory prototype with a 760 V input and a 24 V/60 A output.

A Comparative Study of Empirical and Variational Mode Decomposition on High Voltage Discharges

Signal quality is the key issue for maintaining effective power transmission in electrical networks. In most cases, a high voltage (HV) is transmitted in power systems to decrease power loss. Power quality disturbances are monitored by observing the noise degradation of HV signals. Increased oscillations and high-frequency components of power signals exhibit nonstationary signal characteristics. In this study, a comparative analysis of empirical mode decomposition (EMD) and variational mode decomposition (VMD) was conducted on noisy discharge signals. These techniques were used for adaptive signal decomposition in the time domain, facilitating the evaluation of deeper characteristics of the investigated signal. The HV discharges were obtained using 0.4/40 kV and 8 kVA transformers in a laboratory, and all the current and voltage signal waveforms were recorded using high-frequency current and high-voltage probes. The results demonstrate distinct calculations of EMD and VMD techniques in terms of signal decomposition and extracting intrinsic mode functions (IMFs), which define low- and high-frequency components.

Vector Magnetic Evaluation of Core Material under Stress Conditions

It was clarified that not only the tensile and compressive stress but also the shear stress occur on the surface of the motor core. Therefore it is needed to evaluate the magnetic properties of the core material under the various stress condition. In this paper, we will report about influence of the arbitrary stress on the vector magnetic properties of a non-oriented electrical steel sheet under various magnetic flux conditions. From these results, it was clear that the magnetic field strength and magnetic power loss decrease when tensile, compression, and shear stresses are applied.

FRICTIONAL PROBLEMS IN CONTINUOUSLY VARIABLE TRANSMISSION BELT DRIVES

The article describes the results of the research carried out on the evaluation of the influence of friction pairs (rubber belt – belt pulley in belt drive) on the ability to transmit power. In order to determine the characteristics of the belt drive operation, measurements were made on a real belt drive from the drive train of a light two-wheeled vehicle. The measurement was carried out in conditions of changes in the dynamic load. The measurements of the belt slip on the belt pulley within the whole range of the changes of gear ratios and angular speed of the engine were made. During the tests, belts made from various rubber mixtures were compared. The values of the friction coefficients between the surface of belts and the belt pulley were measured. Model analyses of the impact of belt slip on the wheel related to the temperature of Belt drive elements were also made. Generally, one can ascertain that, in belt drive systems, power losses are a combination of speed losses and torque losses. The increase in the efficiency of belt drives is possible by decreasing power losses. It is possible to obtain the high performance of continuously variable transmission belt drives with a V- belt solely with the proper choice of the design parameters, which is possible only after the exact recognition of the operational characteristics unique to this class of belt drive systems.

Synthesis of the system for minimizing losses in asynchronous motor with a function for current symmetrization

The operation modes of the TVC-AM electric drive in which the power losses can be reduced were mathematically described. It was defined more precisely that what was at issue is the continued operation of an asynchronous motor at artificial characteristics in the region of nominal slip with an energetics better than at the working section of the natural mechanical characteristic. The system of automatic minimization of power losses of asynchronous motors was developed. It was shown that under conditions of feeding the electric drive from a source with asymmetrical voltage, it is necessary to use phase-by-phase control which requires the use of three control channels and three feedback channels. The logic of the feedback action is that when the load on the AM shaft decreases, it reduces the output voltage of the TVC and the motor currents. As a consequence, it becomes possible to maintain equality of the load angles of all phases to the optimum value. This makes it possible to solve the problem of minimizing the AM losses in a case of equality of the load angles to the optimal value and symmetrization due to equality of load angles by the phases of the motor. The quantitative indices of power loss decrease as well as the symmetrization indices when the electric drive is powered from a source with an asymmetric voltage were shown. The features of the power loss minimization system and the ways of improvement of its efficiency were illustrated. It was shown that the use of the proposed control system led to an improvement in both the power and dynamic parameters of the asynchronous electric drive. A 5 to 45 % reduction of power losses in the range of operating moments of 0£М£М bo relative to losses during operation at the main mechanical characteristic was recorded. The symmetrization effect was characterized by a 1.5 to 6 times reduction of the current asymmetry coefficients. The use of a thyristor voltage converter makes it possible to realize controlled transient start-up and braking modes. Symmetrization of the acting currents of the asynchronous motor results in an 80–150 % reduction of vibrational components of the electromagnetic moment in a steady-state regime

Loss Characteristics of 6.5 kV RC-IGBT Applied to a Traction Converter

6.5 kV level IGBT (Insulated Gate Bipolar Transistor) modules are widely applied in megawatt locomotive (MCUs) traction converters, to achieve an upper 3.5 kV DC link, which is beneficial for decreasing power losses and increasing the power density. Reverse Conducting IGBT (RC-IGBT) constructs the conventional IGBT function and freewheel diode function in a single chip, which has a greater flow ability in the same package volume. In the same cooling conditions, RC-IGBT allows for a higher operating temperature. In this paper, a mathematic model is developed, referring to the datasheets and measurement data, to study the 6.5 kV/1000 A RC-IGBT switching features. The relationship among the gate desaturated pulse, conducting losses, and recovery losses is discussed. Simulations and tests were carried out to consider the influence of total losses on the different amplitudes and durations of the desaturated pulse. The RC-IGBT traction converter system with gate pulse desaturated control is built, and the simulation and measurements show that the total losses of RC-IGBT with desaturated control decreased comparing to the RC-IGBT without desaturated control or conventional IGBT. Finally, a proportional small power platform is developed, and the test results prove the correction of the theory analysis.

High light extraction efficiency into glass substrate in organic light-emitting diodes by patterning the cathode in graded superlattice with dual periodicity and dual basis

The newly discovered graded, superlattice photonic crystals with dual periodicity and dual basis present great opportunity for electromagnetic wave control in photonic devices. These graded superlattices can be holographically fabricated by eight beam interference lithography. We have computed, through electrodynamic simulation, the light extraction efficiency of planar, white organic light-emitting diodes where the Al cathode is patterned with the graded superlattice with dual basis. Two graded super-lattices with four-fold and two-fold symmetries are used to pattern the Al cathode. The decrease in power losses to surface plasmon and waveguide modes is explained by the varying plasmon path length and grating cycle, respectively, in the graded pattern. To the authors' best knowledge, the highest light extraction efficiency of 73.1% into the glass substrate in organic light-emitting diodes has been predicted through simulations.