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EN
The first part in this paper presents the steps of the design for required Static Var Compensator (SVC) system to eliminate power quality problems. The second part will discuss the dynamic model in the form of differential equation used for the EAF. The EAF model is then integrated with the SVC model to demonstrate network dynamic interactions during different operating conditions. Finally, comparison between design and actual power quality performance figures measured for actual steel making plant substation are shown at the end to validate the design values.
PL
W artykule opisano projekt układu kompensacji mocy biernej w przedsiębiorstwie hutniczym a następnie analizowano właściwości dynamiczne systemu. Porównano dotychczas istniejący system i nowy system z kompensacja mocy biernej.
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EN
The primary purpose of installing static shunt compensators in power grids is to improve the voltage conditions. Additional reactive power sources increase the system’s voltage stability and enable faster system recovery after a voltage failure. This paper presents the impact of an SVC device’s structure and settings on impedance change in the supply system, and hence on the frequencies at which resonance phenomena can develop.
PL
Celem instalowania kompensatorów statycznych bocznikowych w sieciach elektroenergetycznych wysokich napięć jest przede wszystkim poprawa warunków napięciowych. Dodatkowe źródła mocy biernej zwiększają stabilność napięciową systemu, a także pozwalają na szybszą odbudowę systemu w przypadku awarii o charakterze napięciowym. W artykule zaprezentowano wpływ struktury i wysterowania układu SVC na zmianę impedancji w układzie zasilania, a więc tym samym na częstotliwości, przy których może dojść do wzbudzenia zjawisk rezonansowych.
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Content available Warunki rezonansowe w węźle z kompensatorem SVC
PL
Instalowanie kompensatorów statycznych w sieciach rozdzielczych i przesyłowych służy poprawie profili napięciowych. Kompensatory jako źródła mocy biernej zwiększają stabilność napięciową systemu. Pozwalają także na szybszą odbudowę systemu w przypadku awarii napięciowej. W artykule zaprezentowano wpływ struktury i wysterowania układu SVC na zmianę impedancji w układzie zasilania. Ma to bezpośredni wpływ na częstotliwości, przy których może dojść do wzbudzenia zjawisk rezonansowych.
EN
Installation of static compensators in distribution and transmission networks favours improvement of the voltage profile. Compensators as sources of reactive power increase the voltage stability of the system. They also enable faster restoration of work system in case of voltage failure. The power system is characterized by a high inductance resulting from the nature of its components. Connection of these elements with the compensator system containing capacitive elements, may contribute to the excitation of oscillation resonant in power supply system. The structure and control system of compensator, in addition to the network parameters are influenced by the resonance conditions occurring in its connection point. In this article the research results of influence structure and control of SVC system on the resonance frequencies are presented. It has been found that the change of trigger angle of the TCR thyristors of shunt reactor results in change of its susceptance as well as the value of resonant frequency in a narrow range. On the other hand, switching on next section of TSC causes step changes of resonant frequency. The overlap of these phenomena leads to an increase of frequency ranges at which favourable conditions for the appearance of voltages or currents resonance occur.
PL
Ostatnie lata przynoszą wzrost popularności technologii strumieniowania wideo na podstawie protokołu HTTP. Rosnąca ilość odbiorców usług tego typu sprawia, że istotnymi problemami wpływającymi na jakość dekodowanego wideo stają się: dobór właściwych parametrów wideo w zestawie jego redundantnych reprezentacji oraz wpływ rywalizacji o zasoby sieciowe pomiędzy indywidualnymi strumieniami. Artykuł przedstawia analizę możliwości rozwiązania tych problemów poprzez wykorzystanie kodowania SVC oraz serwerów proxy HTTP.
EN
Recent years have brought increased popularity of streaming video technology based on the HTTP protocol. The growing number of recipient of such services is the cause of the increased importance of the following issues: the choice of the proper gradation of video parameters inside its redundant representation set and the impact of competition for network resources among individual streams on QoE metrics. The article presents an analysis of possible solutions to these issues through the use of SVC encoding and HTTP proxy servers.
PL
Rosnąca ilość ruchu sieciowego, generowanego przez usługi strumieniowe wideo skłania do coraz powszechniejszego stosowania mechanizmów adaptacji, takich jak standard DASH. Artykuł przedstawia analizę możliwości uzyskania sprawiedliwej dystrybucji dostępnych zasobów klientom usług wykorzystujących DASH przy jednoczesnej maksymalizacji jakości wideo odbieranej przez pojedynczych odbiorców. Wynikiem tej analizy jest propozycja struktury systemu, który pozwoli na realizację tego zadania.
EN
The increasing amount of the network traffic generated by video streaming services leads to more and more widespread use of adaptation mechanisms, such as the DASH. The article presents the analysis of the possibility of obtaining an fair distribution of available resources for DASH clients while maximizing the quality of video received by individual recipients. The result of this analysis is to propose the structure of the system, which will allow the implementation of this task.
6
Content available remote Impact of Loads on Power Flow in Power Systems Using PowerApps and ETAP
EN
This paper presents a study of the impact of loads on power flow in power system. It deals with the impact of both the voltage nodes and the transmission of active and reactive power in lines, and therefore the loss of active and reactive power in the system. Flexible Alternating Current Transmission System (FACTS) devices are found to be encouraging in improving voltage stability limit in power systems. This paper investigates the application of FACTS devices (Static Var Compensator, SVC) on a 9-bus multimachine power system, it deal with the line losses and improving voltage stability limit. Amount of increased reactive power generation and line losses are taken as indicators of stressed conditions of a power system. The use of SVC is identified by PowerApps and ETAP software packages. Both software are used for IEEE 9 bus test system and the results obtained are presented and interpreted.
PL
Analizowano wpływ napięć w węzłach i przepływ mocy biernej i czynnej na pracę systemu energetycznego. Artykuł przedstawia badania zastosowania urządzeń FACTS w dziewi1)ęcioszynowym, wielomaszynowym systemie. Wykorzystano oprogramowanie ETAP.
EN
The recent concerns about fossil fuels have made mass transportations such as electric railways more popular than before. Meanwhile, traction loads are generally complex electrical loads that should be managed by the main electric grid when operated by the Railway Company. In this way, static VAr compensators (SVCs) is a precious tool for preserving the power quality of the electric grid in the presence of electric railways. Therefore, this paper discusses the locating of two SVCs in a rail way with modified teaching- learning based optimization (MTLBO). The results are compared with performing the optimization by Particle swarm optimization (PSO) algorithm.
PL
W artykule analizuje się metody optymalizacji położenia i rozmiaru statycznego kompensatora mocy biernej SVCs w sieci trakcyjnej. Do tego celu wykorzystuje się zmodyfikowaną metodę optymalizacji bazującej na algorytmie nauczania/uczenia się MTLBO.
EN
In gravity interpretation methods, an initial guess for the approximate shape of the gravity source is necessary. In this paper, the support vector classifier (SVC) is applied for this duty by using gravity data. It is shown that using SVC leads us to estimate the approximate shapes of gravity sources more objectively. The procedure of selecting correct features is called feature selection (FS). In this research, the proper features are selected using inter/intra class distance algorithm and also FS is optimized by increasing and decreasing the number of dimensions of features space. Then, by using the proper features, SVC is used to estimate approximate shapes of sources from the six possible shapes, including: sphere, horizontal cylinder, vertical cylinder, rectangular prism, syncline, and anticline. SVC is trained using 300 synthetic gravity profiles and tested by 60 other synthetic and some real gravity profiles (related to a well and two ore bodies), and shapes of their sources estimated properly.
EN
In this paper voltage stability is analysed based not only on the voltage deviations from the nominal values but also on the number of limit violating buses and severity of voltage limit violations. The expression of the actual state of the system as a numerical index like severity, aids the system operator in taking better security related decisions at control centres both during a period of contingency and also at a highly stressed operating condition. In contrary to conventional N – 1 contingency analysis, Northern Electric Reliability Council (NERC) recommends N – 2 line contingency analysis. The decision of the system operator to overcome the present contingency state of the system must blend harmoniously with the stability of the system. Hence the work presents a novel N – 2 contingency analysis based on the continuous severity function of the system. The study is performed on 4005 possible combinations of N – 2 contingency states for the practical Indian Utility 62 bus system. Static VAr Compensator is used to improve voltage profile during line contingencies. A multi- objective optimization with the objective of minimizing the voltage deviation and also the number of limit violating bus with optimal location and optimal sizing of SVC is achieved by Particle Swarm Optimization algorithm.
PL
Artykuł prezentuje wybrane modele kompensatorów energoelektronicznych wykorzystanych do analizy ich pracy w systemie elektroenergetycznym. Wykazano wady, jak i zalety modeli, wraz z zaznaczeniem zakresu ich przydatności do modelowania określonych zjawisk.
EN
This article presents selected models of power electronic compensators applied for the analysis of their operation in power system. Advantages and disadvantages of models have been presented with an indication of their usefulness for modeling of specific phenomena.
EN
This paper proposes a combination of the Thyristor Controlled Series Capacitor (TCSC) and Static Var Compensator (SVC) installation for enhancing the damping performance of a power system. The developed scheme employs a damping controller which coordinates measurement signals with control signals to control the TCSC and SVC. Controller performance over a range of operating conditions is investigated through simulation studies on a single-machine infinite-bus(SMIB) power system. In this paper, a current injection model of TCSC is developed and incorporated in the transmission system model. By using equivalent injected currents at terminal buses to simulate a TCSC no modification of the bus admittance matrix is required at each iteration. Furthermore, an ADAptive LInear NEural (ADALINE) network as a model of coordinated control to control the flow injection model, TCSC and SVC is used. The results of this model in the simulation compared with a coordinated FACTS controller (LQR model). As you will see, ADALINE network power system damping is improved.
PL
W artykule przedstawiono propozycję zastosowania układu pojemności szeregowych z łącznikami tyrystorowymi (TCSC) oraz statycznego kompensatora mocy biernej (SVC) do polepszenia wydajności tłumienia oscylacji w sieci elektroenergetycznej. Działanie zastosowanego sterownika poddano badaniom symulacyjnym w zakresie operacyjnym w systemie jednomaszynowym, linii nieskończenie długiej. Opisano model kontroli prądu przez TCSC, który włączono w model systemu przesyłowego. Dodatkowo, w celu zamodelowania kontroli współrzędnych w modelu przepływu TCSC i SVC, zastosowano sieć neuronową typu ADALINE (ang. ADAptive LInear NEural). Wyniki badań symulacyjnych zostały porównane z działaniem sterownika FACTS (model LQR).
EN
Static Var Compensator (SVC) is a popular FACTS device for providing reactive power support in power systems and its placement representing the location and size has significant influence on network loss, while keeping the voltage magnitudes within the acceptable range. This paper presents a Firefly algorithm based optimization strategy for placement of SVC in power systems with a view of minimizing the transmission loss besides keeping the voltage magnitude within the acceptable range. The method uses a self-adaptive scheme for tuning the parameters in the Firefly algorithm. The strategy is tested on three IEEE test systems and their results are presented to demonstrate its effectiveness.
EN
The article presents selected methods of modelling power electronic compensators in order to analyze their operation in the power systems. Advantages and disadvantages of models have been shown with an indication of their usefulness for modelling specific phenomena.
PL
Autor artykułu prezentuje wybrane sposoby modelowania kompensatorów energoelektronicznych, z uwzględnieniem analizy ich pracy w systemie elektroenergetycznym. Przedstawia wady, jak i zalety modeli, a także zakres ich przydatności do modelowania określonych zjawisk.
14
Content available remote Online Control of SVC Using ANN Based Pole Placement Approach
EN
In this study, an online Artificial Neural Networks based Pole Placement algorithm is proposed to stabilize the 2-bus system with nonlinear SVC and variable power. It uses pole placement method. Proposed algorithm are examined in point of improving the bus voltages which change under different demanding powers and the temporary state performance are compared with PID control based results. Simulation results demonstrate a good performance and robustness.
PL
W artykule zaprezentowano online algorytm Pole Placement z wykorzystaniem sieci neuronowych do stabilizacji dwu-szynowego systemu z nieliniowym, SVC (Static Var Compensator) i zmienną mocą.
15
Content available remote A Survey on Flexible AC Transmission Systems (FACTS)
EN
The flexible alternating current transmission system (FACTS), a new technology based on power electronics, proposes an opportunity to improve controllability, stability, and power transfer capability of AC transmission systems. This article presents a comprehensive review and evaluation of FACTS controllers. This paper provides an extensive analysis on the research and improvements in the power system stability development using FACTS controllers. Several technical publications related to FACTS installations have been highlighted and performance comparison of different FACTS controllers has been discussed. Moreover, some of the utility experience, real-world installations, and semiconductor technology development have been outlined.
PL
FACTS (elastyczny system transmisji prądu przemiennego) jest nową technologią bazującą na urządzeniach energoelektronicznych umożliwiającą poprawę sterowalności, stabilności i możliwości przesyłu energii. Artykuł prezentuje przegląd i ocenę kontrolerów stosowanych w tym systemie. Szczególny nacisk położono na porównanie parametrów.
EN
The problem of the FACTS (Flexible Alternative Current Transmission System Devices) location and size for reactive power system compensation through the multi-objective optimization is presented in this paper. A new technique is proposed for the optimal setting, dimension and design of two kinds of FACTS namely: Static Volt Ampere reactive (VAR) Compensator (SVC) and Thyristor Controlled Series Compensator (TCSC) handling the minimization of transmission losses in electrical network. Using the proposed scheme, the type, the location and the rating of FACTS devices are optimized simultaneously. The problem to solve is multi criteria under constraints related to the load flow equations, the voltages, the transformer turn ratios, the active and reactive productions and the compensation devices. Its solution requires the the advanced algorithms to be applied. Thus, we propose an approach based on the evolutionary algorithms (EA) to solve multi-criterion problem. It is similar to the NSGA-II method (Ellitist Non Dominated Sorting Genetic Algorithm). The Pareto front is obtained for continuous, discrete and multiple of five MVArs (Mega Volt Ampere reactive) of compensator devices for the IEEE 57-bus test system (IEEE bus test is a standard network).
17
Content available Voltage Flicker Mitigation Using STATCOM and BESS
EN
The Voltage flicker, a phenomenon of annoying light intensity fluctuation, caused by rapid change in industrial and domestic load such as Electric Arc Furnaces (EAF), rolling mills, welding equipments and pumps operating periodically has been a major concern for supply utilities, electricity regulatory agencies and customers. Static Voltage Compensators (SVC's) and Static Synchronous Compensators (STATCOM) have been able to solve the voltage flicker problem by rapidly controlling the reactive power. But, the control of active power along with reactive power control helps to mitigate the voltage flicker problem more effectively. In this paper, voltage flicker mitigation of EAF with STATCOM along with Battery Energy Storage System (BESS) is presented and performance results of the system using PSCAD/EMTDC software are analyzed.
PL
Spadki napięć występujące w kolejowych układach zasilania można ograniczać poprzez zastosowanie urządzeń FACTS typu SVC i STATCOM. W artykule przedstawiono własności tych urządzeń oraz koncepcje ich stosowania w układach zasilania trakcji kolejowej.
EN
Voltage drops occurring in railway power supply systems can be limited by the use of FACTS devices, type SVC and STATCOM. In this article the features of these devices and the concepts of their use in railway traction power supply systems are presented.
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