The monitoring of power system events on transmission and distribution level by the use of phasor measurements units

ABSTRAC

INCREASING OF THE CAPACITY OF LOW-VOLTAGE NETWORKS WITH HIGHER EXPLOITATION OF THEIR COMPONENTS INCREASING OF THE CAPACITY OF LOW-VOLTAGE NETWORKS WITH HIGHER EXPLOITATION OF THEIR COMPONENTS

ABSTRACT Problems related to the increased exploitation of lowvoltage networks are in every distribution company the subject of constant attention, above all with regard to the liberalisation of the electricity market. This paper's proposal deals with the following problem solving: -Increasing system reliability, -Decreasing operational costs, -Higher exploitation of network components, -System monitoring of the supply points in the network, -Targeted and optimised maintenance. The authors will attempt to solve the following partial problems: a) Maximal exploitation of transformers thanks to better and more precise protection using fuses with special characteristics for the full exploitation and parallel operation of networks makes possible the adjusting the optimal transformer capacity. b) New configurations and new ways of operation networks; parallel operation with weak couplings. c) Connecting dispersed generators with regard to low-power losses and the voltage profile in lowvoltage network (individual contributions) d) Co-ordination of system voltage control in distribution systems with regard to full exploiting voltage tolerance in low-voltage networks. This paper contains examples of realisation of provisions in distribution company and evaluations of individual contributions. This study is finished and particular rules started in operation. When planning the capacity of distribution transformers, HV/LV designers conform to maximal loading in low-voltage networks. The transformers designed this way have in operation small exploitation. Network monitoring is necessary the paper deals with the methods of protection of distribution transformers. The course of the distribution transformer loading is characterised by the maximum in the winter season functioned with electrical heating. To specify the overloading time we modify the actual daily diagram on the two level loading diagram in accordance with CSN IEC 354. The time of the overloading is determined to four hours. The maximal exploitation of transformer thanks to better and more protection using fuses with special characteristics for full exploitation and parallel operation of networks make it possible to adjust the optimal transformer capacity. The target of dimensioning studies is to find the fixed design policies in order to construct simplified technoeconometric models for low-voltage system. These models have as inputs network configurations, load models, any technical constraints, cost models for components, and models for supply interruptions. Results from this model-based study are used to determine the most appropriate electricity supply arrangements, optimal sizes of transformers, optimal standard sizes of cables and distribution lines. The most common network configuration is partially looped network. Under normal conditions, the network can be operated as a radial arrangement with a high degree of reliability. New configurations use under normal conditions totally closed-loop arrangement and for case of a fault is a system disconnected by a weak coupling fuses to radial network. This net configuration has a simple protection system and is inexpensive to recontruct while maintaining all the good qualities of a classical mesh grid. Its good qualities include a low voltage drop, high reliability, and high quality of electricity supply. In the case of old systems with relatively small loads we can use the co-ordination of voltage control in the MV system and changes of the tap on distribution transformers for keeping operation voltage in LV system within the voltage limits given by standards. Generating units connected to LV networks can permanently or temporarily inject power into the grid. Inversely, a client who is also a producer can absorb power at any time. The choice that he makes between these two operating modes depend on the economical approach he chooses for his electricity generating plant as well as for his heat producing unit. His analysis usually takes into account gas sales, electricity purchases and sales prices and his proper needs. The voltage profile along a LV feeder depends on the balance between the power absorbed from or injected into the system by clients and producers and the other clients' power demand. We must seek the optimal point of connection with the network to improve the voltage profile in the LV network without the construction constructing new (MV/LV transformer stations). Losses in low-voltage networks depend mainly on the load and the line material. Every generator affects load flow and loss characteristics. INCREASING OF THE CAPACITY OF LOW-VOLTAGE NETWORKS WITH HIGHER EXPLOITATION OF THEIR COMPONENT

A Novel Power Losses Reduction Method Based on a Particle Swarm Optimization Algorithm Using STATCOM

In the modern electric power industry, Flexible AC Transmission Systems (FACTS) have a special place. In connection with the increased interest in the development of “smart energy”, the use of such devices is becoming especially urgent. Their main function is the ability to manage modes in real time: maintain the necessary level of voltage in the grids, control the power flow, increase the capacity of power lines and increase the static and dynamic stability of the power grid. The problem of system reliability and stability is related to the task of definitions and optimizations and planning indicators, design and exploitation. The main aim of this article is the definition of the best placement of the STATCOM compensator in case to provide stability and reliability of the grid with the minimization of the power losses, using Particle Swarm Optimization algorithms. All calculations were performed in MATLAB

Voltage Quality and Power Factor Improvement in Smart Grids Using Controlled DG Units

The increased penetration of renewable energy sources in the electrical grid, due to the rapid increase of power demand and the need of diverse energy sources, has made distributed generation (DG) units an essential part of the modern electrical grid. The integration of many DG units in smart grids requires control and coordination between them, and the grid to maximize the benefits of the DG units. Smart grids and modern electronic devices require high standards of power quality, especially voltage quality. In this paper, a new methodology is presented to improve the voltage quality and power factor in smart grids. This method depends on using voltage variation and admittance values as inputs of a controller that controls the reactive power generation in all DG units. The results show that the controller is efficient in improving the voltage quality and power factor. Real data from an electrical network have been used in the simulation model in MATLAB Simulink to test the new approach

Modeling and Simulation of the Anticipated Effects of the Synchronous Condenser on an Electric-Power Network with Participating Wind Plants

Installing a synchronous condenser (SC) onto an electricity grid can assist in the areas of reactive power needs, short-circuit strength, and, consequently, system inertia and guarantees better dynamic voltage recovery. This paper summarizes the practical potential of the synchronous condenser coordinated in an electric-power network with participating wind plants to supply reactive power compensation and injection of active power at their point of common coupling; it provides a systematic assessment method for simulating and analyzing the anticipated effects of the synchronous condenser on a power network with participating wind plants. A 33-kV power line has been used as a case study. The results indicate that the effect of the adopted synchronous condenser solution model in the MATLAB/Simulink environment provides reactive power, enhances voltage stability, and minimizes power losses, while the wind power plants provide active power support with given practical grid rules

Voltage Regulation and Power Loss Minimization in Radial Distribution Systems via Reactive Power Injection and Distributed Generation Unit Placement

Distributed Generation (DG) has become an essential part of the smart grids due to the widespread integration of renewable energy sources. Reactive power compensation is still one of most important research topics in smart grids. DG units can be used for reactive power compensation purposes, therefore we can improve the voltage profile and minimize power losses in order to improve the power quality. In this paper two methods will be used to accomplish the mentioned tasks; the first technique depends on the reactive power demand change of the proposed network loads, whereas the second technique uses an algorithm to control DG units according to the measured voltage values in the feeders to generate the needed reactive power. Both methods were applied to different scenarios of DG unit positions and different reactive power values of loads. The chosen DG unit is made up of a Type-4 wind farm which could be used as a general unit where it is able to control reactive power generation in a wider range separately from active power. The simulation results show that using these two methods, the voltage profile could be improved, power losses reduced and the power factor increased according to the placement of DG units

Design of an Emergency Energy System for a City Assisted by Renewable Energy, Case Study: Latakia, Syria

Electrical energy is one of the most important daily needs. Shortage of energy can be very dangerous for any society. This can affect the standard of living and quality of life of the people and even endanger the lives of those in hospitals, and so forth. Developed countries do not face such risks in general because they have well organized electrical systems and high energy security. The developing countries are faced daily with electric system collapses, especially in the case of wars, where many parts of the electrical grid in the country can be damaged and fuel transmission lines for generators cut off. Urban areas in developing countries should have a strategic plan to deal with any unexpected occurrence of energy shortages using any available renewable energy sources. City of Latakia is located in the region which has been suffering from the consequences of war for more than six years. The fact that a high number of migrants from other cities have come to Latakia along with a lack of fuel makes the energy shortage in the city worse. An emergency system could use the cheapest available renewable energy sources in addition to few big portable generators to provide an acceptable energy supply for the most needed requirements of daily life

Testing a new alternative electric furnace for vermiculite concentrates heat treatment

Актуальность. Одним из представителей георесурсов, нашедших широкое применение в различных сферах промышленности, является вермикулит. После обжига концентратов обогащенных вермикулитовых руд в пламенных печах получают вспученный вермикулит. Вспученный вермикулит, благодаря своей слоисто-пористой структуре и высокой отражательной способности, является основой для получения многих термоизоляционных и огнеупорных материалов и изделий, входит в состав строительных материалов, применяется для защиты от радиации. Обжиг вермикулитовых руд в пламенных печах является энергоемким процессом, поэтому активно разрабатываются конструкции электрических модульно-спусковых печей. Данные печи снизили удельную энергоемкость процесса обжига, в связи с этим работы по созданию электрических печей актуальны. В работе рассмотрены вопросы, связанные c созданием и испытанием новой альтернативной электрической печи для обжига вермикулитовых концентратов. Цель исследования: экспериментальное определение энерготехнологических показателей опытного образца печи с вибрационной подовой платформой при его испытаниях. Методы исследования: анализ источников информации в области исследования, синтез конструктивных решений, физическое моделирование, параметрическое и функциональное описание, экспериментальные исследования. Результаты. Разработана альтернативная электрическая модульно-спусковая печь для обжига вермикулитовых концентратов с принципиально новой конструктивной структурой - печь с вибрационной подовой платформой. Создана полномасштабная физическая модель печного агрегата - однофазный одномодульный блок, на которой проведены эксперименты и получены эмпирические данные. При проведении экспериментальных исследований достигнута плотность вспученного вермикулита 90…91 кг/м3и производительность 3,56 м3/ч. Значение удельной энергоемкости обжига вермикулита различных видов составляет 63,7…81,6 мДж/м3, что почти втрое меньше, чем у существующих пламенных печей, работающих на углеводородном топливе.Relevance. Vermiculite is one of the representatives of geo-resources that are widely used in various industries. The expanded vermiculite is obtained by heat treating of vermiculite ore concentrates in open flame furnaces. Expanded vermiculite, due to its layered-porous structure and high reflectivity, is the base for obtaining many thermo-insulating and refractory materials and products. Vermiculite is a part of building materials, and it is used to protect against radiation. Heat treating of vermiculite ores in flaming furnaces is an energyintensive process; therefore the designs of electric modular-trigger furnaces are being actively developed. These furnaces have not significantly reduced the specific energy intensity of the firing process, that is why the work on creation of electric furnaces is up-to-date. This research is aimed to develop and construct a furnace prototype of a fundamentally new design. The aim of the research is the experimental determination of operational specifications of a furnace model with a vibrating bottom platform which is a separate single-phase firing module during testing. Methods: analysis of information sources in the field of research, synthesis of constructive solutions, physical modeling, parametric and functional description, experimental studies. Results. The authors have developed the alternative electric furnace for firing vermiculite concentrates with a fundamentally new design structure which is a furnace with a vibrating bottom platform. A full-scale physical model of the furnace unit - a single-phase and single-module unit, was developed. Using the above-mentioned physical model the authors carried out the experiments and obtained the empirical data. During the experimental studies, the density of the expanded vermiculite was 90…91 kg/m3 and the productivity was 3,56 m3/h. The value of volume energy for various types of vermiculite roasting is 63,7…81,6 mJ/m3, which is almost three times less than that of existing open flame furnaces operating on hydrocarbon fuel

Testing a new alternative electric furnace for vermiculite concentrates heat treatment

Актуальность. Одним из представителей георесурсов, нашедших широкое применение в различных сферах промышленности, является вермикулит. После обжига концентратов обогащенных вермикулитовых руд в пламенных печах получают вспученный вермикулит. Вспученный вермикулит, благодаря своей слоисто-пористой структуре и высокой отражательной способности, является основой для получения многих термоизоляционных и огнеупорных материалов и изделий, входит в состав строительных материалов, применяется для защиты от радиации. Обжиг вермикулитовых руд в пламенных печах является энергоемким процессом, поэтому активно разрабатываются конструкции электрических модульно-спусковых печей. Данные печи снизили удельную энергоемкость процесса обжига, в связи с этим работы по созданию электрических печей актуальны. В работе рассмотрены вопросы, связанные c созданием и испытанием новой альтернативной электрической печи для обжига вермикулитовых концентратов. Цель исследования: экспериментальное определение энерготехнологических показателей опытного образца печи с вибрационной подовой платформой при его испытаниях. Методы исследования: анализ источников информации в области исследования, синтез конструктивных решений, физическое моделирование, параметрическое и функциональное описание, экспериментальные исследования. Результаты. Разработана альтернативная электрическая модульно-спусковая печь для обжига вермикулитовых концентратов с принципиально новой конструктивной структурой - печь с вибрационной подовой платформой. Создана полномасштабная физическая модель печного агрегата - однофазный одномодульный блок, на которой проведены эксперименты и получены эмпирические данные. При проведении экспериментальных исследований достигнута плотность вспученного вермикулита 90…91 кг/м3и производительность 3,56 м3/ч. Значение удельной энергоемкости обжига вермикулита различных видов составляет 63,7…81,6 мДж/м3, что почти втрое меньше, чем у существующих пламенных печей, работающих на углеводородном топливе.Relevance. Vermiculite is one of the representatives of geo-resources that are widely used in various industries. The expanded vermiculite is obtained by heat treating of vermiculite ore concentrates in open flame furnaces. Expanded vermiculite, due to its layered-porous structure and high reflectivity, is the base for obtaining many thermo-insulating and refractory materials and products. Vermiculite is a part of building materials, and it is used to protect against radiation. Heat treating of vermiculite ores in flaming furnaces is an energyintensive process; therefore the designs of electric modular-trigger furnaces are being actively developed. These furnaces have not significantly reduced the specific energy intensity of the firing process, that is why the work on creation of electric furnaces is up-to-date. This research is aimed to develop and construct a furnace prototype of a fundamentally new design. The aim of the research is the experimental determination of operational specifications of a furnace model with a vibrating bottom platform which is a separate single-phase firing module during testing. Methods: analysis of information sources in the field of research, synthesis of constructive solutions, physical modeling, parametric and functional description, experimental studies. Results. The authors have developed the alternative electric furnace for firing vermiculite concentrates with a fundamentally new design structure which is a furnace with a vibrating bottom platform. A full-scale physical model of the furnace unit - a single-phase and single-module unit, was developed. Using the above-mentioned physical model the authors carried out the experiments and obtained the empirical data. During the experimental studies, the density of the expanded vermiculite was 90…91 kg/m3 and the productivity was 3,56 m3/h. The value of volume energy for various types of vermiculite roasting is 63,7…81,6 mJ/m3, which is almost three times less than that of existing open flame furnaces operating on hydrocarbon fuel