Losses In Electrical Systems Research Articles

Optimization of losses by switching to higher voltage in distribution networks

The article considers the basis of scientific research in the field of electric power industry the issues of transition to 20 kV voltage in the distribution power grids of Uzbekistan. The main advantages of this method are analysed, as well as the factors affecting power and energy losses in electrical systems and networks. The paper presents a schematic diagram of an electric network section, on which a comparative calculation and analysis of voltage, energy and power losses in 6/10/20 kV networks is carried out. Special attention is paid to the peculiarities of calculation of these parameters, as well as the basic expressions for their calculation and the resulting graphical relationships. From the analysis it can be concluded that it is reasonable to use 20 kV voltage in distribution networks. It allows to reduce power and energy losses, which is an important factor in the efficient operation of electric power systems, to increase line capacity and service range. However, when selecting the optimal voltage for certain conditions, it is necessary to take into account a number of factors, such as the length of transmission lines, the type of wires and transformers used, and the load level of the network.

Impact study of flexible alternating current transmission system on power flow and power loss in power systems using MATLAB and PSAT

The work presented in this paper is to study the impact of FACTS (flexible alternating current transmission system) on the power flow and power losses of a multi-machine electrical system. In this work, we have calculated the power flow and the active and reactive power losses for a 6-bus 3-machine network system, in the first case where there are no FACTS, and in the second case where there are FACTS (SVC). So, and in the second case we used an SVC ((Static Var Compensator) because it is one of the elements of FACTS, to see their influence on power flow and power losses in electrical systems using MATLAB software (we used the Newton-Raphson method) and using PSAT software (Power System Analysis Toolbox), we calculated the power flow and the active and reactive power losses in the lines, respectively. Finally, we compare the results obtained by the simulation programs MATLAB and PSAT, and see what effect FACTS (SVC) has on the power flow and power loss in our electrical system that we are studying.

Impact of Electrical Topology, Capacity Factor and Line Length on Economic Performance of Offshore Wind Investments

In this study, an economic performance assessment of offshore wind investments is investigated through electrical topology, capacity factor and line length. First, annual energy yield production and electrical system losses for AC and DC offshore wind configurations are estimated by using Weibull probability distributions of wind speed. A cost model for calculating core energy economic metrics for offshore wind environment is developed by using a discount cash flow analysis. A case study is then conducted for a projected offshore wind farm (OWF) rated 100 MW and 300 MW sizes situated in the Aegean sea. Finally, a sensitivity analysis is performed for AC and DC OWFs with three different capacity factors (e.g., 45%, 55% and 60%) and various transmission line lengths ranging from 20 km to 120 km. The OWF is found to be economically viable for both AC and DC configurations with the estimated levelized cost of electricity (LCOE) ranging from 88.34 $/MWh to 113.76 $/MWh and from 97.61 $/MWh to 126.60 $/MWh, respectively. LCOEs for both options slightly change even though the wind farm size was increased three-fold. The sensitivity analysis reveals that, for further offshore locations with higher capacity factors, the superiority of AC configuration over the DC option in terms of LCOE reduces while the advantage of DC configuration over the AC option in terms of electrical losses is significant. Losses in the AC and DC configurations range from 3.75% to 5.86% and 3.75% to 5.34%, respectively, while LCOEs vary between 59.90 $/MWh and 113.76 $/MWh for the AC configuration and 66.21 $/MWh and 124.15 $/MWh for the DC configuration. Capacity factor was found to be more sensitive in LCOE estimation compared to transmission line length while line length is more sensitive in losses estimation compared to capacity factor.

6.5 kV Si/SiC Hybrid Power Module Technology

Substituting Si diodes with SiC Schottky diodes in Si insulated gate bipolar transistor (IGBT) modules is beneficial, as it can reduce power losses in electrical systems significantly. The fast switching nature of the SiC diode will allow Si IGBTs to operate at their full high-switching-speed potential, which at present is not possible because of the Si diodes. In this work, the electrical test results for Si-IGBT/4HSiC-Schottky hybrid substrates (hybrid SiC substrates) are presented. Comparisons of the 6.5 kV Si and hybrid SiC at room temperature and high temperature have shown that the switching losses in hybrid SiC substrates are low as compared to those in Si substrates but necessary steps are required to mitigate the ringing observed in the output waveforms.

Estimating power factor of induction motors at any loading conditions using support vector regression (SVR)

Three-phase induction motors are industrial work horses known as inductive loads. Inductive loads always create low power factor due to consuming more reactive power. Low power factor not only makes a penalty charge for costumers, but also produces energy losses in electrical systems. To prevent these problems, the power factor which is the ratio of active and reactive power must be maintained toward unity. The power factor can be controlled by manipulating either of active or reactive power. In induction motors, active power is proportional to the motor load that variation of motor load results in increase or decrease in power factor. However, adding reactive power by capacitors would be a substantial solution to improve and control the power factor in unity. Many researches expressed that injecting improper reactive power to improve the power factor creates under- and over-correction. To prevent such problems, equation of power factor correction can be employed in order to obtain the optimal value of reactive power. In this equation, the presence of power factor at every single loading point is required. Estimation techniques can be a significant key to determine the power factor at every loading point. In this paper, several statistical methods including, kriging, regression, artificial neural network and support vector regression, are tested in three induction motors. A comparison is presented to verify the great performance of support vector regression method.

A Case Study Survey of Harmonic Currents Generated from a Computer Centre in an Office Building

Due to the growing use of non-linear load equipment and new technologies in buildings, harmonic currents generated in distribution systems pose a new problem for electrical engineers. This is a serious problem when power quality is a prime concern. The problem is due to some non-linear loads showing different current waveforms when supplied by a distorted voltage. This paper summarises the results of a case study survey in an office building with a large number of connected computers, a major source of harmonics. The scope of work included site measurement and analyses. The characteristics and effects of harmonic distortion of load current and voltages on distribution systems are discussed. It was found that on most occasions, careful planning and design can minimise the risk of harmonic-related losses in electrical systems. However, this does not always guarantee satisfaction. A bank of capacitors may be used to improve power factors in electrical systems, though in some cases such a bank may make the situation worse. An alternative is filters, but the position of filters is also crucial. Based on the case study, the paper discusses alternatives and provides some practical solutions to the problem of harmonics in office buildings.

Theory of wind-electric water pumping

A proper understanding of the electrical and mechanical behavior of the system and its components is essential for the successful operation of a wind-electric pumping system. In the present article we present a formal theory of such a system, developing a framework for the determination of the steady-state operating point, as well as the study of its transient behavior, particularly at start-up. It is shown that the sufficient accumulation of kinetic energy in the wind turbine before connecting it to its load is critical for a successful start-up, even when the system has been designed to function at optimal steady-state conditions. A detailed discussion of the start-up process in terms of stored kinetic energy in the braking power provided by both the pump and the electrical system losses is given. The results of this analysis are believed to be useful both for the steady-state design of wind-electric pumping systems, as well as the optimization of control schemes and energy capture.