High controllability advantages of power electronic switches led to their application in tap-changers of distribution transformers. For an existing transformer, with a set of regulating windings and taps, an optimal tap changer should maximize the voltage steps with a minimum number of solid-state devices. It explains logically and systematically the design and optimization of a full electronic tap-changer for distribution transformers. In these cases, the main responsibility of controller in the tap-changer system is minimization of the voltage amplitude deviation rising and falling of voltage in respect to the reference voltage at a point technically called regulation bus. © 2018 Institute of Electrodynamics, National Academy of Sciences of Ukraine. A novel commutation technique without necessity to measure current is developed and presented.
Replacement of the mechanical or hybrid switch of the tap changer with solid state switches for two power and voltage levels is studied in the paper A distribution transformer tap changer with continuous operation of tap changing and control of the secondary voltage brings a remarkable improvement in power supply quality, keeping the voltage in the net constant. This arc causes contamination of the oil surrounding the diverter switches and also leads to the erosion of their contacts. Specific examples of calculations are presented. This was while reliability and quality were not taken into account seriously Bollen Understanding power quality problems. Different solutions are suggested in the paper and verified by simulation and experimental study.
Using such switches leads to quick operation of the tap-changer and, thus, improved performance. Meanwhile, the impact of the electronic tap-changer in power quality parameter improvement is compared with that of other custom power tools. The book is written for electrical engineers in industry and academia but should be useful also to postgraduate students of electrical engineering. Commutation cell with bi-directional switch and high frequency switching is a basic building element of a solid state tap changer. A model for the controller of an electronic tap changer is designed by making some modifications in conventional controller. Regarding of these impacts, recent advances in static grid voltage support functionalities to increase penetration level are compared considering voltage rise limitation.
In such a case a traditional tap-changer cannot react well, while an electronic tap-changer enables to operate properly. Badania przeprowadzono na podstawie ogólnodostępnych modeli elemen- tów sieci elektroenergetycznej. Using such switches lends itself to quick operation of the tap-changer and thus improved performance. Since static electronic tap-changers do not have moving parts in the current path only simple maintenance is required and there are almost no limitations in the number of operations during their lifetime. The hybrid switch is composed of a mechanical switch and two semiconductor switches which are used for steady state and tap change operation respectively.
In the control section design, the authors review mechanical tap-changer control systems and they present the modeling of a full electronic tap-changer as well as a closed-loop control of the full-electronic tap-changer. The book is written for electrical engineers in industry and academia but should be useful also to postgraduate students of electrical engineering. This is carried out keeping all transformers in the same tap position. . The highest voltage among these off-state voltages is chosen as the standing voltage of the particular switch. A general structure of an electronic tap-changer and the simulation of the modified controller are then presented.
But they had considerable limitations and drawbacks like arcing, high maintenance, service costs and slow reaction times. A model of the controller of a mechanical tap-changer system is then presented. A low level control mechanism is also developed, thus providing a holistic design for building a prototype. In this chapter realization of these switches is presented, static behavior and current commutation is explained. Then using this winding structure and switch arrangement an optimal topology is presented, realization of bi-directional switch and its commutation is also presented. One major assumption in the design of the controller in Part I of the paper was that a quick technique was available for detecting the amplitude and phase angle of the sinusoidal variables.
The mechanical switch ensures low steady state losses and the semiconductor switches are used for arc-free tap changing. Tap changing in the mechanical tap-changer generates arc in the contacts of the diverter switches. The system is then simulated to show its capabilities for sag mitigation and power quality enhancement. Following the realization of the tap-changer controller, developed software for such precise control is introduced. A novel design of taps comprised of several no-load switches and a single semiconductor-mechanical hybrid switch have been proposed, that requires reduced voltage rating and a number of switches. To this end, the analytical computation for determining the compensating of sag limit of the electronic tapchanger is given. The aims of this optimisation include minimisation of: 1 number of switches and their voltages and currents, 2 number of taps in the transformer, 3 deviation of the amplitude of voltage compared with the reference voltage in the regulation bus and finally increasing number of voltage steps.
The cost generally depends on the number, voltage and current rating of each power electronic switch. But for many decades, electricity suppliers had concentrated on generation, transmission and distribution of electrical energy to the consumers. Earlier mechanical type of on load tap changers were into practice. Several variants of such reconfiguration are considered. The reason was that those days lighting was the most important load of consumers.
This paper introduces a new solid-state onload tap-changer topology that has many steps with fewer power electronic switches compared with those reported in the literature. In addition, the structure of the transformer and insulating requirements will be simpler and its relevant cost will be lower if the number of taps are reduced. Meanwhile, the whole tap changing process in the mechanical tap-changer is basically performed mechanically. The vision is to introdu ce reconfigurable dc links as a flexible backbone to future distribution grids in order to enable a smooth transitioning from ac to dc transmission systems. The book provides a fully new insight to all possible structures of power section design and categorizes them comprehensively, including cost factors of the design. However, there is no arc in the full-electronic tap-changer during the tap-changing and also no moveable mechanical part. In this paper, a new scheme for on-load tap-changer of a transformer is presented, which can eliminate excessive conduction losses and suppress the arcing in the diverter switch, which are inherent in traditional on-load transformer tap-changers.
Description: 1 online resource xii, 183 pages. The topologies are designed in such a way that they can provide both positive and negative compensation of the grid voltage. Furthermore, undesired smart grid phenomena like increased dynamic behaviour due to greater fluctuations in load and generation, decreased power quality, increased harmonic distortion, reactive power demand and decrease of system inertia may be mitigated. This paper presents the capability of the distribution transformer equipped with an electronic tap-changer for improving power quality. On the other hand, more voltage steps over the particular range of voltage regulation leads to the possibility of more precise voltage regulation, which is very desirable. A novel design of a partially rated autotransformer is proposed which has taps developed through a combination of no-load switches and a single hybrid switch. The voltage in the medium voltage 10 kV and low voltage 400 V utility networks is controlled with the change of the transformer ratio tap changing.