Entire Power Supply Research Articles

Diagnostic approach in assessment of a ferroresonant circuit

This paper presents possibilities offered by a diagnostic system called FeD. The system is completely original; it has been developed by the authors on the basis of Arduino platform. The system has been designed to perform and record measurements and to carry out different numerical operations. The real-time function for several operations is incorporated in this system. The necessary input data for the system consist of the electrical voltage waveforms only. Rescaled voltage quantities can be displayed, measured, recorded or computed in any chosen way. The system has been developed particularly for measurements and computations in the ferroresonant circuits. The strongest part of the system is its versatility. It works with a standard PC and supports a universal connection (USB standard). This is undeniably a cost-wise solution. Driving and control of the system functions are carried out using the authors’ original software implemented in SciLab environment. This is free software, similar to and compatible with other existing CAD programs such as Octave and MATLAB. The obtained data, scripts and results can be freely transferred between them. The program is equipped with a transparent GUI. The need of constructing a special system to diagnose the ferroresonant circuit has emerged during earlier ferroresonance analyses and computations. Every ferroresonant circuit requires specific kind of diagnostics to estimate and display its base features in order to determine the best scientific approach to the problem. The ferroresonance phenomenon belongs to the domain of nonlinear problems. Its analysis requires excellent skills in mathematics and physics as well as computer science. Moreover, this subject also requires specialized engineering knowledge, particularly in the field of power engineering and power system equipment. Modern mathematical models and analyses used in ferroresonant computations are quite accurate; however, in case of a common user, they are often difficult to understand or implement. This paper provides full description of construction, features and test results of the developed hardware/software system designed for diagnostics of ferroresonant circuits. The test circuit case study has been performed in the entire power supply range. Results of measurements and computations as well as screenshots captured from authors’ original software are shown in different figures. The developed software and recorded data have been finally used in modeling and further simulations. During this, the application of the fractional derivative iron core coil model to ferroresonance analysis has been shown. The waveforms obtained from computer simulations have been compared with those obtained from measurements performed in the test circuit.

Impacts of Earthquakes on Energy Security in the Eurasian Economic Union: Resilience of the Electricity Transmission Networks in Russia, Kazakhstan, and Kyrgyzstan

In our research, we focus on the reliability of the interconnected electricity supply system of three countries of the Eurasian Economic Union (EAEU)—Russia, Kazakhstan, and Kyrgyzstan. We apply a mathematical model to evaluate the reliability of the electricity supply system under the threat of earthquakes. Earthquakes can damage elements of electricity grids and, considering the interconnectivity of electricity supply systems in the EAEU, effects in the aftermath of earthquakes can be far-reaching and even transboundary. This necessitates the development of coordinated policies and risk management strategies to deal with electricity outage risks in the EAEU. In our study, the earthquake probability is derived from seismic zone maps, while damage events are computed using maps of energy power systems. In addition, we determine which elements of the system are susceptible to failure due to an earthquake of a given magnitude. We conduct a scenario analysis of earthquakes and their impacts on the reliability of the power supply system, considering potential energy losses and threats to energy security. An analysis of the resilience of electricity transmission grids allows us to determine the critical interconnection lines in terms of exposure to earthquake risk, as well as exposure to total systemic loss. We also identify the most critical interconnection lines where power outages can lead to the destabilization of the entire power supply system. Some examples of such lines are at the border of Kazakhstan and Kyrgyzstan, where power outages can lead to serious economic costs and electricity outages.

Regulatory reform of energy and economic growth in Japan

Deregulation of the electric power business began in the middle of the 1990s in Japan, and after several law revisions, the electric power market was fully liberalized in April 2016. On the other hand, the Japanese government has also adopted the FIT system, which gives incentives for introducing renewable energy power, as a means for reducing greenhouse gas emissions in 2012. In this paper, we take up regulatory changes involving deregulation and global warming countermeasures, analyze the facts and impact, identify the problems that appear as side effects, and consider the impact on economic growth. The conclusion obtained is as follows. Deregulation has certainly stimulated the power market and has provided new entrants, new price menus and value-added services. Especially in the latter half of the 1990s and early 2000s, electricity prices declined, and productivity measured by TFP improved. The price cut was due to the reduction of capital costs by the existing dominant electric power companies, although after the Lehman shock in 2008, neither price reduction nor productivity improvement can be confirmed. Meanwhile, the FIT has played a role in expanding renewable energy power. However, it not only raised the cost of electricity but also became a factor impairing the stability of the entire power supply. Japan’s electricity supply system is shifting to a stage where additional measures for stable supply are required.

Definition of the dependability index of power supply systems

The article shows that one of the important indicators of energy efficiency is the index (index) of dependability of electricity supply, which is characterized by a decrease in the share of damage from interruptions of power supply in the gross domestic product. The questions of obtaining an expression for the optimal value of the degree of dependability are considered taking into account the values of the reduced costs and their economic and energy components.The significance of an assessment of damage caused by a shortage of electricity is shown in the absence of an emergency reserve. The damage caused by asymmetry and nonsinusoidal tension, on average, is several times less than the voltage associated with the deviations and is most pronounced in the metallurgical and engineering industries. An expert assessment of the annual losses associated with the low quality of electricity in Ukraine and in the world is given.The importance of the problem of improving the quality of electric energy was stressed; attention was drawn to the increased role of the sinusoidal distortion of the voltage curve in determining the dependability of electricity supply, as well as its relation to the economic indicators of the country's development. Virtually all indicators of the quality of electrical energy affect the dependability and economic performance of electrical equipment and ultimately affect the efficiency of the entire power supply system. It is shown the importance in specific cases of exceeding the cost of measures to correct the levels of nonsinusoidality over the value of economic damage. The values of the power supply dependability index in the complex of the energy efficiency index are formulated; the values of the specific capital investments in the reserve generating capacity are given. Estimated calculations of dependability indices of electric power industry subjects of Ukraine are given.In the conclusions, it is justified to apply the minimum of the given costs as a criterion for estimating the dependability of the power supply system with the equality of the optimization values of the dependability index.

Mathematical Approach to Identification of Load Structure at the Nodes of the Distribution Grids 6–10 kV and 0.4 kV

A significant increasing energy efficiency of the full cycle of production, transmission and distribution of electricity in grids should be based on the management of separate consumers of electricity. The existing energy supply systems based on the concept of «smart things» do not allow to identify the technical structure of the electricity consumption in the load nodes from the grid side. It makes solving the tasks of energy efficiency more difficult. To solve this problem, the use of Wavelet transform to create a mathematical tool for monitoring the load composition in the nodes of the distribution grids of 6–10 kV, 0.4 kV is proposed in this paper. The authors have created a unique wavelet based functions for some consumers, based on their current consumption graphs of these power consumers. Possibility of determination of the characteristics of individual consumers of electricity in total nodal charts of load is shown in the test case. In future, creation of a unified technical and informational model of load control will allow to solve the problem of increasing the economic efficiency of not only certain consumers, but also the entire power supply system as a whole.

Research on automatic current sharing control methods for control power supply

High-power switching devices in control power supply have different saturated forward voltage drops and the inconsistency of turning on/off times and they lead to the inconsistency in the external characteristics of the inverter modules in parallel operation. Modules with good performance in external characteristics undertake more currents and lead to overloading status and modules with bad performance in external characteristics stay in light-loading status, which increases the thermal stress of module undertaking more currents and influences the service life of high-power switching devices. Based on the simulation analysis of the small-signal module using control power supply automatic current sharing method, it is able to find out the characteristics of current-sharing loop control, namely, slow response speed of the current-sharing loop, which is beneficial for improving the stability of the entire control power supply system.

An On-Die All-Digital Power Supply Noise Analyzer With Enhanced Spectrum Measurements

A scalable all-digital power supply noise analyzer with 20 GHz sampling bandwidth and 1 mV resolution is demonstrated in 32 nm CMOS technology for enabling low-cost low-power in-situ power supply noise measurements without dedicated clean supplies and clock sources. This subsampled averaging-based analyzer measures power supply noise in both the equivalent-time and frequency domains with low-resolution VCO-based ADCs. For equivalent-time measurements, the accurate impedance characterization of power delivery networks is simply done by measuring a clock-synchronized current-step response. For frequency-domain measurements, the digital random phase-noise accumulation technique is analyzed and verified to overcome the clock-and-noise correlation issue in autocorrelation measurements. In general large scale integrated circuits and systems, the entire power supply noise analyzer consumes negligible active and leakage powers because of the MHz-range sampling clock frequency and fully digital implementation with only hundreds of logic gates.

Improving energy performance and mains voltage quality by means of power electronics

The possibilities of improving energy performance of valve inverters in phase regulation and high-and low-frequency pulse modulation are considered. In some cases, the use of circuit design and special methods of control and artificial switching considerably reduced reactive power consumption, but did not make it possible to a sufficient degree to solve the higher harmonics problem and ensure the consumption of sine current from the mains. Particular attention is paid to the use of the active voltage rectifier. Devices that ensure power supply to any customers together with improving the energy performance of the entire power supply system and the quality of its voltage are called “active rectifying compensators of passive power.” The way these devices are controlled ensures that the total mains current consumed by all customers approaches the optimal level, i.e., it is sine current with voltage-relative shift angle φ (for example, φ = 0). Mains voltage fluctuations can be reduced by making the control over a group of ac converters with low-frequency pulse modulation and active load depend on mains current changes. The advantages of the combined ac/dc power supply system are presented.

IC power delivery

Modern IC power delivery systems encompass large on-chip passive power grids and active on-chip or off-chip voltage converters and regulators. While there exists little work targeting on holistic design of such complex IC subsystems, the optimal system-level design of power delivery is critical for achieving power integrity and power efficiency. In this article, we conduct a systematic design analysis on power delivery networks that incorporate Buck Converters (BCs) and on-chip Low-Dropout voltage regulators (LDOs) for the entire chip power supply. The electrical interactions between active voltage converters, regulators as well as passive power grids and their influence on key system design specifications are analyzed comprehensively. With the derived design insights, the system-level codesign of a complete power delivery network is facilitated by a proposed automatic optimization flow in which key design parameters of buck converters and on-chip LDOs as well as on-chip decoupling capacitance are jointly optimized. The experimental results demonstrate significant performance improvements resulted from the proposed system cooptimization in terms of achievable area overhead, supply noise and power efficiency. Impacts of different decoupling capacitance technologies are also investigated.

Basic Electronics: AC Transformers

Basic Electronics: AC Transformers

AVALIAÇÃO DO IMPACTO DAS DESCARGAS ATMOSFÉRICAS NA QUALIDADE DE ENERGIA FORNECIDA PELAS CONCESSIONÁRIAS: ESTUDO DE CASO EM UMA EMPRESA DE DISTRIBUIÇÃO DE ENERGIA DO SUL DO PAÍS

This article has the objective of evaluate the impact of atmospheric discharges in power quality supplied by electricity companies. To start the analysis, it has been chosen a case study, collecting data in a participant observation, providing a portrait of the analyzed phenomenon. Nowadays, the traditional evaluation indexes are already defined and they are included in all procedures of the entire power supply system. These indexes already consider the economic aspects of loss of power quality, for the residential and industrial costumers, because atmospheric discharges can cause power supply interruption, and, often, damages in the costumers’ electric equipments. This situation can cause a lack of thrust in the organizational image. Costumers, nowadays, are often looking for their rights through resolutions, laws and the Costumer Defense Code. These laws refer to the resolutions edited by the National Agency for the electric sector, and they try to minimize the damage caused.

To enhance the efficiency of a power supply circuit by the use of Fe–P–B–Nb-type ultralow loss glassy metal core

The inductor in a power supply is required to be capable of dealing satisfactorily with the high-current supply and to improve the power loss characteristic. A novel glassy metal powder with a chemical composition Fe77P7B13Nb3 features both a high saturated magnetic flux density of 1.3 T and a low coercive force of 2.0 A/m, which has a stable amorphous structure suitable for glassy metal composite cores. Hence there is no magnetic saturation even under a high-current supply, and it is confirmed to have significantly low magnetic loss resulting from the low coercive force. As a result of using the glassy metal alloy Fe77P7B13Nb3 powder in an inductor core, we have achieved improvement in power supply efficiency by up to roughly 2.0%. Moreover, the reduction in the standby power requirement by the improvement in the power supply efficiency in the low load current case, where the core loss occupies a high ratio in the entire loss, can be expected. Additionally, heat generation in a core is suppressed by using the low loss powder, and it becomes easy to design a temperature rise in the entire power supply circuit.

Development of ion source with a washer gun for pulsed neutral beam injection

A new type of economical neutral beam source has been developed by using a single washer gun, pulsed operation, and a simple electrode system. We replaced the conventional hot filaments for arc-discharge-type plasma formation with a single stainless-steel washer gun, eliminating the entire dc power supply for the filaments and the cooling system for the electrodes. Our initial experiments revealed successful beam extraction up to 10 kV and 8.6 A, based on spatial profile measurements of density and temperature in the plasma source. The system also shows the potential to control the beam profile by controlling the plasma parameters in the ion accumulation chamber.

Optimal endogenous carbon taxes for electric power supply chains with power plants

In this paper, we develop a modeling and computational framework that allows for the determination of optimal carbon taxes applied to electric power plants in the context of electric power supply chain (generation/distribution/consumption) networks. The adoption of carbon/pollution taxes both internationally and regionally has been fueled by global climate change and fuel security risks, with a significant portion of such policy interventions directed at the electric power industry. The general framework that we develop allows for three distinct types of carbon taxation environmental policies, beginning with a completely decentralized scheme in which taxes can be applied to each individual power generator/power plant in order to guarantee that each assigned emission bound is not exceeded, to two versions of a centralized scheme, one which assumes a fixed bound over the entire electric power supply chain in terms of total carbon emissions and the other which allows the bound to be a function of the tax. The behavior of the various decision-makers in the electric power supply chain network is described, along with the three taxation schemes, and the governing equilibrium conditions, which are formulated as finite-dimensional variational inequality problems. Twelve numerical examples are presented in which the optimal carbon taxes, as well as the equilibrium electric power flows and demands, are computed. The numerical results demonstrate, as the theory predicts, that the carbon taxes achieve the desired goal, in that the imposed bounds on the carbon emissions are not exceeded. Moreover, they illustrate the spectrum of scenarios that can be explored in terms of changes in the bounds on the carbon emissions; changes in emission factors; changes in the demand price functions, etc.

Optimum design of a high-power, high-frequency transformer

A procedure for optimum design of a high-power, high-frequency transformer is presented. The procedure is based on both electrical and thermal processes in the power transformer and identifies: (a) the VA-rating of ferrite cores in relation to the operating frequency; (b) the optimum flux density in the core; and (c) the optimum current densities of the windings providing maximum transformer efficiency. Since the transformer is the major contributor to the volume and weight of the power supply, the results of transformer analysis can be used for entire power supply optimization as well. Two high-power, high-frequency transformers are optimally designed, built, and tested. Practical results show good agreement with the theory.

SF System: Power Conversion

This article describes the constant current, high voltage power facilities which power the SF Submarine Cable repeaters. The overall power system description includes discussions of the power connections to the cable, and a review of overall design requirements and objectives. The circuit description is covered in a general manner to demonstrate the basic concept. Particular emphasis is given to the description of several significant circuit innovations which include automatic load sharing by two constant current sources, 20 kHz inverter operation with output wave symmetry correction, solid-state alarm detectors, automatic turn-up and turn-down features, electrical noise suppression, redundant shutdown circuits and selective alarm cutoffs. The physical design includes the extensive use of plug-in modules for ease of maintenance, convection cooling of the entire power supply including the test load, and a key interlock system which prevents access to high voltage components when the power supply is energized. A special high-voltage switch can transfer the cable from one power plant to another without interruption of service.

Power Supply Study and New Rectifier Installation for the United Electric Railways of Providence

A study of the power supply to the United Electric Railways was initiated when new construction necessitated the re-location of rotary converters. Replacement with modern equipment was considered in conjunction with a comprehensive study of the entire power supply. It was evident that the losses on the United Electric Railways feeder and trolley system would be the controlling economic factor. A method of calculating the losses in this d-c supply system was developed, correlated with a measured value of losses, and extended to determine the relative merits of proposed feeder changes and rectifier installations. It is believed that this is the first published study that has made use of available probability methods for calculating losses, voltage drop, flicker, and capacity requirements in a study of the power supply for an electric transportation system. The rotary converters were replaced with 60-cycle rectifiers at two new locations. The design of these substations incorporated certain novel features for the protection of equipment and personnel.