Voltage Electrical Networks Research Articles

Overvoltage on the High and Low Side Electrical Network Voltage 35 kV When Appearing and Disconnecting Short Circuits of Various Forms at Its High Voltage Part

Overvoltage on the High and Low Side Electrical Network Voltage 35 kV When Appearing and Disconnecting Short Circuits of Various Forms at Its High Voltage Part

Re-design and Analysis of 220 KV Multi – Circuit Transmission Tower

A transmission tower or power tower is a tall structure, typically a steel lattice tower, which is employed to support an overhead power line. Economic losses will be the consequence of any transmission line system failure that disrupts the energy supply. This article describes the MD (300-600 Dev./D.E.-00) NT +9M body extension redesign and structural analysis for a 220 kV multi-circuit transmission tower. This paper pertains to the failure transmission tower structure and implementation of the failure structure through the use of CAD, ANSYS, and analytical and experimental testing. Experimental testing in 2018 resulted in the failure of this MD type transmission tower. The research conducted in this paper is the first to analyse and track the progression of failure of a segment of a transmission structure, in contrast to previous studies that have examined the behaviour and failure of a single tower. To accomplish this, a distinctive CAD/numerical model is developed in this paper. This article will provide a comprehensive discussion of the formulation and validation of the various components of this CAD/numerical model, which are reported in various sections of paper. This study helps build transmission towers to handle rising voltage and power demands in electrical networks.

SIMULATION AND RESEARCH OF SINGLE-PHASE SHORT CIRCUITS IN THE ELECTRICAL NETWORK

The purpose of this work is to model single-phase short circuits in a three-phase electrical network and identify their type by analyzing the angular frequency of the spatial vector. Recently, the saturation of electric networks with powerful non-linear loads, the introduction of conversion equipment and renewable energy sources lead to the need for systematic analysis and research of the quality of electric energy (QEE). One of the factors that significantly affect the operation of electrical equipment is short circuits. In the article, based on the developed model of the formation of QEE distortions, a single-phase short circuit in a three-phase electrical network is investigated by switching it to a single-phase system with two α-β projections and a zero-sequence voltage vector.
 Studies of the influence of the location of the short-circuit point on the voltage in the electrical network have shown that the difference in the distance from the point of damage to the load, type of short-circuit leads to varying degrees of voltage change. Conducted studies have shown that different types of malfunctions and parameters of the electrical network at the point of short circuit cause different disturbances in the electrical voltage in the power supply system. The presence of a short circuit of the same type at different locations leads to different voltage drops and overvoltages. Short-term changes in voltage are the most common distortions of the quality of electrical voltage in electrical networks. The simulation results based on the developed model are consistent with the theory and reliably simulate the change in voltage in the electrical network.
 In the future, the presented model can help in creating a basis for the identification and subsequent control measures of voltage change violations.

Energy efficiency of circulating pumps when using non-freezing heat transfer fluids

Introduction. The article considers the issues of operation of circulating pumps of autonomous heat supply systems when the heating circuit is filled with antifreezing coolants. It is possible to remotely start up a heating system cooled down to –15 °С. Ethylene glycol and propylene glycol antifreeze have been studied as antifreeze carriers. Flow-rate characteristics, power efficiency coefficients are studied for “wet rotor” circulation pumps in versions of electric motors of asynchronous type with constant rotor speed and energy-saving pumps on permanent magnets.
 Materials and methods. The research was carried out on test stands. Wall-mounted gas boilers and electric boilers witha rated capacity up to 24 kW were used as heat generators. Circulation motors, control hydraulic valves, part of the pipes with a length of 6 meters were located in a separate freezer. The pumps and parts of the heating circuit were kept at subzero temperatures for 2 hours before the system was started up
 Results. Pressure and flow characteristics of two types of pumps, energy efficiency coefficients were obtained, comparisons with water coolant are provided, the influence of electric network voltage on the investigated parameters was determined.
 Conclusions. The research has shown the possibility of starting circulating pumps in a refrigerated condition with a temperature of –15 °С. Remote start of the cooled heating system with circulation circuit filling with antifreeze when using hydrocarbon fuel boilers is not possible. Operation of heating systems with non-freezing coolants in the operation temperature ranges of 20–80 °C requires changing in settings of the combustion process and a significant increase inthe circulation pump head in comparison with the coolant water.

ВИКОРИСТАННЯ ШТУЧНИХ НЕЙРОННИХ МЕРЕЖ ДЛЯ ПРОГНОЗУВАННЯ ВИРОБЛЕННЯ СОНЯЧНОЇ ЕНЕРГІЇ НА ФОТОЕЛЕКТРИЧНИХ ЕЛЕМЕНТАХ

Purpose. Development of an artificial neural network for modeling time series of forecasting electricity generation taking into account the use of a renewable energy source using MATLAB&Simulink software. Methodology. Theoretical and experimental research with the help of software implementation of fundamental knowledge in the field of electricity generation using renewable energy sources; simulation of artificial neural network prediction; methodology of mathematical statistics and forecast analysis. Results. Based on the conducted research and implemented solutions, this article developed a time series modeling system for forecasting solar energy production using Simulink. Defined control parameters and corresponding time series; the analysis of the input data showed the influence on the generated electrical energy of such meteorological parameters as solar radiation on the surface of the earth and on the surface of the panel, temperature of the panel and the environment, cloud cover and time of day. In order to ensure the appropriate accuracy of forecasting the generated power, there was a task to ensure the accuracy limit of forecasting meteorological parameters. Scientific novelty. The novelty of the given research lies in the formation of the balance of electricity in the power system with the help of an artificial neural network, influencing the choice of mode parameters and calculated loads. The balance between production and consumption of electricity is a fundamental aspect of the technological sustainability of the energy system. Violation of this balance can lead to deterioration of power quality, including changes in frequency and voltage in electrical networks, which can affect the efficiency of equipment. Practical significance. Neural network forecasting allows effectively distribute the load between different objects of the power system. This makes it possible to manage electricity consumption by adjusting the load of equipment. For example, the main electricity generation can be shifted to hours and zones of the wholesale electricity market with lower prices to reduce the cost of electricity generated from renewable energy sources.

Methodological approach to assessing additional active power losses in overhead power lines at non-sinusoidal modes

Non-sinusoidal voltage in electrical networks is one of the most pressing problems in the field of power quality. In non-sinusoidal modes in electrical networks, in addition to losses of active power at the fundamental frequency, i.e. at the 1-st harmonic, active power losses occur at frequencies that are multiples of the fundamental frequency, corresponding to harmonics from 2 to 40. Additional harmonic active power losses increase losses in electrical networks, creating economic damage for both energy companies and consumers. The paper provides a review of the literature on the topic under consideration. A methodological approach is proposed to assess additional active power losses in overhead power lines. Based on the methodological approach, an analysis of the power quality indicators characterizing the non-sinusoidal mode, measured at the point of connection of 110 kV transmission line to the electrical network, was carried out, additional active power losses were determined.

Voltage stability assessment prediction using a guide strategy-based adaptive particle swarm optimisation-neural network algorithm

<span lang="EN-US">In this work, the indicators of electrical power network stability and voltage stability (VS) are discussed and developed with the aim of using a power transfer stability index (PTSI) indicator as a predictor for voltage stability (VS) in electrical power networks. The power transfer stability index (PTSI) was thus used to detect abnormally weak voltages in buses within such power system networks (weak). The target data are obtained using the Newton Raphson method (NR) and include magnitude, phase angle, and active and reactive power. A new adaptive particle swarm optimization-neural network algorithm based on a guiding strategy (GSAPSO-NN) was also used to achieve the goal of the paper by improving the mixed particle updates and the weightings of the neural network to decrease the search time. All results were then compared with actual values as calculated using the PTSI NR method. The final results show only simple differences or approximately the same values using both the proposed and the classical methods. The MATLAB-PSAT package was employed to obtain most of these results and the testing of the new method was done on the IEEE14 bus system as well as the Iraqi 24-bus power system. The effectiveness validation of the new hybrid method for assessing voltage stability was thus achieved.</span>

Разработка алгоритмов и программного обеспечения для силовых активных фильтров судовых электроэнергетических систем

The use of electrical receivers with a non-linear load on ships significantly affects the electric power characteristics. The main devices that reduce the distortion of the sinusoid of current and voltage in electrical networks are active, passive and combined filters. There are considered the main types and principles of active filters operation, shown the current methods for detecting a distortion and forming a compensating effect by active filters. Using the active filters for electric drives of reciprocating mechanisms with an uneven, but periodic predictable load on the shaft is demonstrated. The operation of such devices in the ship electrical power system worsens the electric power characteristics (e.g. high iTHD, harmonic components). The effectiveness of using an active filter operating on a perturbation from a reference signal for electric drives of reciprocating compressors has been theoretically grounded. There has been presented an algorithm for operation on a perturbation determining the spectrum of the selected interharmonic distortion and presenting it in the form of a Fourier series to create a compensating effect. Application of the algorithm helps increase the speed of the control system, eliminates temporary errors and simplifies the operation of the system. The range of active filters operation according to this algorithm is found limited due to a necessary periodic load or fixed interference. The control software for a three-phase active filter was designed by using the algorithms. The software project is presented in the MATLAB/Simulink mathematical modeling environment. A specific feature of the software using a memory block to organize the calculation of the compensation pattern for harmonic distortion and using the algorithms for generating a compensating signal in the frequency domain. The hardware modeling is considered and the firmware of the board is made. The interface, code and results of the software work are given. It has been inferred that the software effectively controls the power elements of the active filter with current feedback.

BACKSTEPPING CONTROL AND ADAPTIVE OBSERVER DESIGN FOR A SINGLE-PHASE GRID-CONNECTED PHOTOVOLTAIC SYSTEM

In this paper, we consider the problem of controlling a single-phase grid-connected photovoltaic system using the backstepping technique and an adaptive observer. The conversion system includes a PV panel, a DC-DC Boost converter, a DC-AC half bridge inverter connected to the grid via an LCL filter. This work aims at achieving threefold control objectives: i) extracting the maximum available power ii) guaranteeing a unitary power factor (UPF) by forcing the grid current to be sinusoidal and in phase with the electric network voltage, iii) regulating the DC link voltage to a desired references value. The performance of the proposed regulator is evaluated through numerical simulation using MATLAB/SIMULINK environment.

Daily wind-based interruption prediction in Enedis' Medium Voltage Overhead Lines using time series data

Overhead lines represent about 50% of the French Medium Voltage/Low Voltage electrical network. Therefore, most of the French electrical network is vulnerable to weather conditions. In order to optimize financial investments, and plan maintenance campaigns, a reliability model would be helpful, especially if based on three main features of the electrical network: the intrinsic reliability linked to natural ageing, the sensibility to frequent weather conditions, and its vulnerability to extreme and rare climatic hazards which it is more difficult to hedge. The history of electrical failures is used to tune and build this model in order to propose a failure rate made of those three features. Then we will present a machine learning model which predict a few days ahead of time, the number of failures caused by the prevailing winds of a French area.

An Adaptive Synchronverter for Ensuring Fault Ride Through Capability of Grid-Connected Solar Power System

In recent years, the grid-connected solar power system has grown tremendously because of its cost-effectiveness and environmental friendliness. However, its interface to the existing power grid introduces frequency and voltage instability due to its lack of rotating mass and inertia response, unlike a conventional synchronous machine. To alleviate the limitations, a novel adaptive synchronverter is proposed to equip with fault ride through in a grid-connected solar power system. It enables continuous electricity generation even under overloading, voltage sag or short circuit fault. MATLAB®/Simulink simulations are conducted, and it is validated by emulated hardware by Typhoon® Hardware-in-the-loop (HIL) 402 real-time simulation. The results validated that the fault ride through capability enables the synchronverter to stay connected in short periods of lower electric network voltage.

Analysis of Electrical Distribution Network Voltage Configuration with Mixed Integer Linear Programming Algorithm and Genetic Algorithm I Terms of Energy Cost

Analysis of Electrical Distribution Network Voltage Configuration with Mixed Integer Linear Programming Algorithm and Genetic Algorithm I Terms of Energy Cost

Improving the optimal system of automated control over the level of electric power quality indicators in electric networks

This paper reports solving an important scientific task of minimizing the economic losses caused by the established deviation and the asymmetry of voltage in the distributing electrical networks with a rated voltage of 10 kV.It has been found that the existing systems of automated control over the mode parameters of distributing electrical networks do not fully take into consideration the multifunctional influence of symmetry-compensating devices at the level of electricity quality indicators.It has been proposed to use, as the criteria functions for the task on automated control over the electric power quality indicators, the functional dependences that assess the level of losses caused by the established deviation and asymmetry of voltage in electrical networks. That has made it possible, in contrast to existing control systems, to better account for the negative impact of the established deviation and asymmetry of voltages on the modes of electric network operation.We have determined the functional dependences between the input and output parameters of the control object (a distributing electric network with a voltage of 10 kV with a symmetry-compensating device), which formed the basis of the criteria functions for a multi-criteria optimization problem. The ultimate solution to the problem on a multi-criteria optimization based on a method of approaching a utopian point in the criteria space was derived by minimizing the Chebyshev distance from the utopian point to a Pareto-optimal set of solutions. Based on the obtained solution to the problem on a multi-criteria optimization, we have built an algorithm for determining the vector of optimum control.Computer simulation of the optimal automated control system for the power quality indicators in distributing electrical networks has been performed.Analysis of the simulation results has revealed that the automated control system proposed in this work, when compared with the existing ones, makes it possible to reduce the negative effect exerted by the above-the-norm values of the established deviation and asymmetry of voltage on the operation of electrical networks

Review of Voltage and Reactive Power Control Algorithms in Electrical Distribution Networks

The traditional unidirectional, passive distribution power grids are rapidly developing into bidirectional, interactive, multi-coordinated smart grids that cover distributed power generation along with advanced information communications and electronic power technologies. To better integrate the use of renewable energy resources into the grid, to improve the voltage stability of distribution grids, to improve the grid protection and to reduce harmonics, one needs to select and control devices with adjustable reactive power (capacitor batteries, transformers, and reactors) and provide certain solutions so that the photovoltaic (PV) converters maintain due to voltage. Conventional compensation methods are no longer appropriate, thus developing measures are necessary that would ensure local reactive and harmonic compensation in case an energy quality problem happens in the low voltage distribution grid. Compared to the centralized methods, artificial intelligence (heuristic) methods are able to distribute computing and communication tasks among control devices.

Investigation of Voltage Unbalance Profile in Low Voltage Electrical Distribution Network with Normal Mode Operation Using MATLAB

With ever increasing use of semiconductor devices and information technology (ICT) equipment in the industry, homes and offices, power quality is gaining attention to both industry and the electric utility. Power voltage quality cause huge economic losses to businesses all over the world. It is estimated to cost industry and commerce about €100 billion per annum in European Union, since voltage quality problem is one of the major power quality disturbances. This paper presents an investigative a study of the 11/0.4 kV, low voltage electrical distribution network and analyzes voltage unbalance. It recommends an effective method of improving the voltage profile and reducing the voltage unbalance to acceptable standard. The network was modelled using distribution network standard parameters for low voltage distribution network using MATLAB/Simulink sim power system tool box. The simulation results show that the percentage voltage unbalance, correct voltage profile and minimum voltage drop of 0.5 km distribution feeder line is of standard acceptable statutory limit, hence the distribution line operates at optimum performance. However, it is also established that the voltage profile for distribution network feeder lengths of 0.8 km to 5 km for balanced and unbalanced distribution lines from the beginning to the customer terminal of the distribution lengths are less than the acceptable allowable limit of – 5 %, of the nominal voltage value, hence voltages are inadmissible for customers use. Moreso, the percentage voltage unbalance, voltage profile and voltage drop on 0.8 km to 5 km distribution feeder line are all less than standard acceptable statutory limit, hence the distribution line operates below optimum performance. It was established that mitigating these problems require the electricity distribution company to install an effective voltage boosting devices along the network lengths in order provide admissible, permissible and normalize end users standard acceptable voltage.

ELECTRIC SUPPLY OF UNDERGROUND CONSUMERS OF DEEP ENERGY-INTENSIVE MINES

The increase in the capacity of cleaning and construction vehicles for highcapacity and energy-intensive mines calls for an increase in the supply voltage of cleaning and tunneling combines, as well as transport systems: from a voltage of 660 V switched to 1140 V, and now to 3300 V. This allows improving technical and economic indicators for clearing and access areas, as well as improving the reliability of local Power Supply Systems (PSS). However, this trend prevents the supply of underground electric networks with a voltage of 6 kV, in connection with which the problem arises of increasing the voltage of supply networks. To date, it has become possible to apply the 10 kV voltage to the operation, which is most acceptable for the use of electrical equipment for electrical networks and protection devices. Leading educational, research and design organizations were engaged in research on this issue. An analysis of the results of the research showed that switching to 10 kV voltage is justified and timely. At the same time, 35 kV voltage is not removed from the agenda, which is technically feasible and economically justified, but there are problems with the safety of its operation in underground workings, which requires appropriate refinement. This level of voltage will improve the quality of electricity.Conclusions: 1. Application of 35 kV voltage in the underground power supply system of coal and ore mines is advisable at a depth of more than 1000 m with a maximum load of at least 1000 kVA at the level of the stem cables.2. Application of 35 kV voltage in underground electrical networks will allow to significantly improve the quality indicators of voltage, reliability, and economy of the system due to the current unloading of the most important element of SES, such as stem cables.3. Analysis of the main parameters and characteristics of electrical mine electrical equipment gives reason to believe that it allows implementing a trend of 35 kV deep input to deep horizons of mines (mines) and placement of 35/6 kV substations on working horizons.

Extension algorithm for generic low-voltage networks

Distributed energy resources (DERs) are increasingly penetrating the energy system which is driven by climate and sustainability goals. These technologies are mostly connected to low- voltage electrical networks and change the demand and supply situation in these networks. This can cause critical network states. Network topologies vary significantly and depend on several conditions including geography, historical development, network design or number of network connections. In the past, only some of these aspects were taken into account when estimating the network investment needs for Germany on the low-voltage level. Typically, fixed network topologies are examined or a Monte Carlo approach is used to quantify the investment needs at this voltage level. Recent research has revealed that DERs differ substantially between rural, suburban and urban regions. The low-voltage network topologies have different design concepts in these regions, so that different network topologies have to be considered when assessing the need for network extensions and investments due to DERs. An extension algorithm is needed to calculate network extensions and investment needs for the different typologies of generic low-voltage networks. We therefore present a new algorithm, which is capable of calculating the extension for generic low-voltage networks of any given topology based on voltage range deviations and thermal overloads. The algorithm requires information about line and cable lengths, their topology and the network state only. We test the algorithm on a radial, a loop, and a heavily meshed network. Here we show that the algorithm functions for electrical networks with these topologies. We found that the algorithm is able to extend different networks efficiently by placing cables between network nodes. The main value of the algorithm is that it does not require any information about routes for additional cables or positions for additional substations when it comes to estimating network extension needs.

Analysis And Study On Distribution Of Defect Electric Field On Basin-type Insulator In GIS

With the increase of electric network voltage in power system, the internal discharge phenomenon of gas insulated substation (GIS) during operation often happens. In this paper, a 3-D simulation model of GIS with metal protrusion on basin-type insulator was utilized to study the effect of metal protrusion on the electric field distortion in GIS. It can be concluded from simulation results that the electric field increases with the height of metal protrusion when the radius is constant, while decrease with the increase of radius of metal protrusion. In addition, the metal protrusion near high voltage conductor lead to more severe electric field distortion than that near grounded enclosure. This work is of significance for the actual operation and maintenance of GISs in the power system.

Planificación y Diseño Automático Óptimo de Grandes Redes Eléctricas de Distribución: Aplicación al Centro Histórico de Quito

El presente trabajo describe la herramienta computacional desarrollada por CoDyPower (CDP) para la planificación automática óptima de grandes redes eléctricas de distribución. El objetivo principal es el diseño de redes eléctricas que minimicen el coste económico de la instalación y operación. La función de coste a optimizar tiene en cuenta el número y tipo de subestaciones, la longitud y tipo de conductores, la instalación de líneas aéreas o subterráneas y los costes de operación y pérdidas en un horizonte temporal dado. La optimización considera la geometría de las calles, los catálogos de transformadores y cables disponibles para el proyecto, las restricciones de distancias, caídas de tensión, corrientes y potencias máximas. Debido al carácter computacional NP-hard del problema, el software aplica estrategias de inteligencia artificial y de estadística, fraccionando el problema en etapas de macro y micro optimización. Con ello se encuentra un camino viable de cálculo en tiempos de computación accesibles. Además, los algoritmos propuestos son capaces de encontrar soluciones multi-circuito para cada transformador. El presente trabajo muestra también la aplicación del software CDP al diseño y planificación de las redes eléctricas de distribución de baja y media tensión del Centro histórico de Quito, con unos 20.000 usuarios. Los resultados obtenidos cumplen todas las especificaciones y reducen en aproximadamente un 40% el coste inicialmente estimado.

DVR시스템에 사용되는 인버터부의 LC필터 설계와 피드백 성능분석

Voltage sags are considered the dominant disturbances affecting power quality. Dynamic voltage restorers(DVRs) are mainly used to protect sensitive loads from the electrical network voltage disturbances such as sags or swells and could be used to reduce harmonic distortion of ac voltages. The typical DVR topology essentially contains a PWM inverter with LC Filter, an injection transformer connected between the ac voltage line and the sensitive load, and a DC energy storage device. For injecting series voltage, the PWM inverter is used and the passive filter consist of inductor(L) and capacitor(C) for harmonics elimination of the inverter. However there are voltage pulsation responses by the characteristic of the LC passive filter that eliminate the harmonics of the PWM output waveform of the inverter. Therefore, this paper presented design and feedback performance of LC filter used in the DVRs. The voltage control by LC filter should be connected in the line side since this feedback method allows a relatively faster dynamic response, enabling the elimination of voltage notches or spikes in the beginning and in the end of sags and strong load voltage THD reduction. Illustrative examples are also included.