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The following topics are dealt with: power quality; distribution system planning; interharmonic distortion; renewable generation; distributed power generation; and smart grids.
The paper deals with finding the optimal shape of the electromagnet by changing skew keeper and skew pole shoe of the electromagnet so as to obtain maximum tensile force. The solution used numerical methods, especially the program COMSOL.
Today design, deployment, and operation of modern substations are changing significantly. IEC 61850 (61850) leads the way, as a notably improved global standard. 61850 is the result of years of research by leading utility industry experts seeking to provide a universal standard addressing all significant aspects of modern substation communication. This paper supports 61850 as a worthy vehicle for...
This paper proposes the use of low voltage digital protection units, available for installation inside circuit breakers, as measuring instruments to monitor power quality. Because circuit breakers are already installed for protection of low voltage circuits, and they include current and voltage sensors, no additional instrumentation would be required. Performance of current devices in terms of power...
In this paper, a new method for modeling transmission lines with frequency dependent electrical parameters for time domain transient studies is presented. The model is based on the Method of the Characteristics. The frequency dependence is included by means of a rational approximation of the transient resistance. The results are compared to those from a frequency domain method and from the ATP/EMTP.
This paper studies the effects of using compact fluorescent lamps (CFLs) on the power distribution system elements on both the generation and the consumption sides. Previously, we presented a comprehensive analysis of how the harmonic distortion is generated in the CFLs and how it affects the distribution system wave shape. Here we study the technical and practical issues of mass utilization of CFLs...
This paper summarizes the research concerning the practicability of a new Power Quality concept, "Process Immunity Time" (PIT). Process Immunity Time has been developed as a new concept by a CIGRE/CIRED/UIE working group, starting from experience with voltage dips in the chemical industry. In order to know if PIT is a generic concept for other industrial sectors, a number of voltage dip...
Preliminary recalling the idea of generalized sinusoid, fundamental concepts of cisoidal algebra are then exposed. The approach is regarded as a generalization of the classic phasors analysis and it is proposed for the analysis of circuits and electromagnetic fields in damped steady state conditions. In this way is possible to reformulate the energetic balance by means of the concept of contra-rotating...
This paper considers the harmonic supply voltage evaluation of non linear distorted loads, such as diode bridges, arch furnaces and so on, connected to medium voltage cable line. The connection to the MV grid allows a cost reduction of the measuring and protection apparatus, but it introduces problems such as the low short circuit power that can cause a high harmonic voltage distortion. The paper...
The first part of this paper contains a short review on problems related to distribution system operators' (DSOs) current practice regarding earth fault location and sustained faulty operation of compensated networks. A new device and method are then presented that have been implemented recently at Hungarian DSOs. This technique uses current injection parallel to the Petersen coil for fault location,...
In this paper an improvement of wavelet based methods for detection and classification of power quality disturbances is presented. In the feature extraction process wavelet analysis is also used as in the comparing methods. However, the feature vector is extended with three other coefficients in order to improve the accuracy of the algorithm. In order to evaluate the proposed method, large number...
Reliability has always been the central focus of network operators. However, today they must also focus on sustainability and efficiency. The ever increasing use of intermittent renewable energy sources and the need to reconfigure the network based on efficiency seem to counter the quality of supply standards set forth by regulators. Maintaining the balance between quality, reliability and efficiency...
Electric traction is one of the biggest appliances in power network and can have a significant influences on supply network. These influences include non-harmonic currents and voltages, unsymmetric loading of the three phase system or rapid fluctuation in power consumption. Traction network, feeding network, traction transformer and, in some cases, filtration-compensation unit, altogether form a system...
This paper describes the technique developed to charge and to regulate the hybrid active power filter link DC. The developed strategy is based on the Modified Synchronous Reference Frame Controller. The ability of the hybrid topology in charging and regulating its own Link DC without external sources connection is analyzed. The accuracy and the dynamics are presented, and the measurements of active...
Current harmonics can produce undesired effect on protection devices, the most common being nuisance tripping on instantaneous overcurrent protections. This paper focuses on the effects of harmonics on overcurrent protection devices, describing the structure and behaviour of circuit breakers fitted with thermal-magnetic trip units and with electronic trip units. Situations in which undesired effects...
The paper gives a novel approach to decide if a voltage dip was severe or the equipment attended should operate continuously during the dip. The method gives the possibility to create simple but characteristic general indices like the well known SAIDI. Results of long term measurements will be evaluated with the proposed method and compared with the norm-like classification.
The concept of magneto-electric root mean square (RMS) is extended to the motional cases, where electromechanical energy conversion processes are concurrently present. Emerge, with undiminished physical meaning, the concepts of mechanical RMS of force f(t) and velocity u(t). In this way is possible, regarding the instantaneous conversion relation pm(t)=f(t)·u(t)=e(t)·i(t)=pe(t) in terms of RMS values,...
In order to determine apparent power and its components the currents and voltages are presented in the shape of orthogonal functions. On this ground values of active and reactive powers are determined as components of a scalar product of the voltage and current vectors. An example of calculation of powers in thyristor controlled RL -load is presented. Here the vector of input voltage is formed taking...
Inasmuch as there are many single phase unbalanced linear and non linear loads in distribution system, current flows through null wire. Because of voltage drops of null wire, load voltage will be unbalance. Different methods have been presented for compensation of load current compensation, which shunt active filter is one of them. Shunt active filter is effective on source current, and it can compensate...
In the paper the application of energy storage for enhancing distributed energy sources penetration and contributing to better quality of energy delivery to customers was investigated. A simulation method was used to study the effectiveness of complex control algorithms of energy storage system enabling load leveling and simultaneous voltage stabilization effect in grid-connected microsystem. The...
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