A Short note on Harmonics and Filters in HVDC systems (original) (raw)
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Active filtering of AC harmonics from HVDC converters
1997
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Harmonic Analysis of a Non-Conventional HVDC System
The advent of power electronics and proliferation of non-linear loads in industrial power applications, power harmonics and their effects on power quality are a hot topic of concern. Harmonics are the byproducts of modern electronics. They occur frequently when there are large numbers of personal computers (single phase loads), uninterruptible power supplies (UPS), variable frequency drives (AC and DC) or any electronic device using solid state power switching supplies to convert incoming AC to DC. Non-linear loads create harmonics by drawing current in abrupt short pulses, rather than in a smooth sinusoidal manner. The harmonics can be described as "a sinusoidal component of a periodic wave or quantity having a frequency that is an integral multiple of the fundamental frequency." Some references refer to "clean" or "pure" power as those without any harmonics. But such clean waveforms typically only exist in a laboratory. This paper aims to compare the harmonic outputs of the conventional inverter and star-delta inverter. PSCAD/EMTDC software is used in simulation of the output harmonics of the mentioned inverters. Results show that the star-delta inverter gives similar output harmonic behavior like the conventional inverters.
Harmonic analysis on LVDC distribution system and passive filter techniques for harmonic reduction
2015 2nd International Conference on Electrical Information and Communication Technologies (EICT), 2015
Usages of DC power instead of AC power on the secondary distribution system creates a lot of harmonics. Our goal is to eliminate the harmonics onto the system and due to the limited specification of filter it has not been possible to reduce all the harmonics in the secondary distribution system. But we must be more focused to achieve this goal, because large shares of household loads are turning into DC in recent years. If this trend continues, the impact of harmonics on customer end will reach a level which might be detrimental and redundant to both loads and grid. The main objective of this research is to explain the effects of harmonics on the low voltage direct current (LVDC) distribution system and measure the harmonic content present in the network and proposed a recovery method by inserting filter. Due to additional non-linear loads on the LVDC distribution system, a sufficient amount of harmonics will be created. To solve this issue, use of passive harmonic filter is recommended for the DC operated secondary distribution system. After using a passive filter into the LVDC network, the system harmonics are being reduced into the acceptable limits and almost eliminate the harmonics generated by the converter and nonlinear loads.
The Geomagnetically induced current adversely effects the power system. Main impact of geomagnetically induced current is on power transformer and also HVDC converter transformer. Because of the interaction of the solar storm on earth, there is a occurrence of DC bias current. Many harmful effects are observed in the HVDC converter transformer. The invasion of geomagnetically induced current into the converter transformer is through neutral wire which will result into the saturation of converter transformer core saturation. This leads to the production of harmonics in the power system. Because of the harmonics, many other adverse effects are seen to be occurring which includes heating of transformer core, windings may burn, etc. This paper presents the techniques to inhibit the invasion of Geomagnetically induced current into the converter transformer neutral. Furthermore, it gives a comparative study of the various techniques by examining it in MATLAB/SIMULINK.
A combination of rectifier and DC -DC chopper is useful in feeding DC loads where the DC input to the loads needs to be stepped up or down. Both rectifier and chopper are based on power electronic switches which inject harmonics in the system. This harmonics is an undesirable effect which should be mitigated effectively. For this, passive harmonic filters are used. Passive harmonic filters are a simple and economical option for harmonic mitigation. Thus they find widespread application in various power systems. This paper deals with the analysis of harmonic distortion caused in a typical AC system feeding a DC motor through a rectifier and boost chopper setup. The analysis is done before and after the incorporation of passive harmonic filters on the AC side in order to study the effect of the same in the mitigation of source side harmonics.
Design Of Passive Harmonic Filter For Ac Drives
2018
Harmonic distortions is form of electrical pollution that can cause a problems, if the sum of harmonic current is increases above limits, a harmonic current is one with the frequency at the multiple of fundamental frequency. For a instance of 250Hz current on a 50Hz network is a 5th harmonics , 250Hz currents represents energy that cannot be used by the devices on the network it will be converted into heat. cause cables to overheat. damaging their insulation. Motors may also overheat or become noisy and torque oscillations in the rotor can lead to mechanical resonance and vibration. Capacitors overheat with, in the most worst cases, the risk of explosion as the dielectric breaks down. Electronic displays and lighting may flicker, circuit breakers can trip, computers fail and meters give false readings. Harmonic currents and voltages are created by non-linear loads connected on the power distribution system. All power electronic converters used in different types of electronic system...
Innovative Filter Concept For Power System Harmonics
ICHPS V International Conference on Harmonics in Power Systems., 1992
A modification to conventional harmonic filters used in HMC Stations and similar equipment is proposed. A rectifier is used to recover energy from several tuned filters. and the amount of energy recovered controls filter quality Q. n r~h a M a C Thus. low+ filters can be desimed without the VoftagaSourra Two-Winding Transformer I Nonllnear Load attendant power losses. Such f i l t e r s are desirable from the point of view of simplicity, robustness. and stability. The 'minimum losses filter' concept is explained through simulation studies of operating characteristics and Its application to an existing HYDC terminal. 1981 he has been on the faculty of the Department of Electrical and Computer Engineering,
DESIGN OF AN ACTIVE DC FILTER FOR A HVDC SYSTEM_Gayatri Mohapatra
2011
Active filter have become the most viable alternat ives for the compensation of the harmonics in the power system analysis. Thes e filters are able to reduce the harmonics percentage much lower than selective passive filters and also provide compensation for the loss occurring in the transmission system. This project basically deals with the operational charac teristics of the active shunt filter design for a specific voltage rating irrespe ctive of the load connected. This is basically used to reduce the harmonic component present in the output of the converter in the HVDC application. This basically d eals with the detection of the percentage of harmonic content in the percentage of the undamental by using the FFT analysis of the signal and the design the a ctive filter with the concept of selective harmonics compensation for specific harmo nic rder. Active filters are basically working with the conc ept of providing the same negative current in the passive filter part to canc el ...
2015 2nd International Conference on Electrical Information and Communication Technologies (EICT), 2015
Due to the different types of conversion purposes lots of harmonic creates in DC operated power system. Our goal is to minimize the harmonics at a certain level. The main focus of this research is to explain the effects of harmonics in a 12-pulse High Voltage Direct Current (HVDC) transmission network and take corresponding steps to reduce those effects. It includes harmonic reduction technique to improve the power quality of the HVDC transmission system. This paper also explains how harmonic distortion in HVDC network is one of the important problems associated with power quality and creates several disturbances to the overall power system. In this paper, simulation results were developed on the basis of bus no 1 and 2 of an ideal HVDC transmission Link where there are a lot of harmonics created primarily both in voltage and current due to the presence of Transformer, Converter Devices and Nonlinear Loads. After using passive filter, this harmonic level will be minimized at a certain point which is explained in details on this paper with practical justification.
Reducing the effects of harmonics on the electrical power systems with passive filters
Bitlis Eren University Journal of Science and Technology, 2015
Users or customers of the electrical power systems must pay attention to some factors during operation and design of these systems in order to operate safe and in desired format. One of these factors is harmonic caused by non-linear elements determining the quality of the power as a parameter. Some harmful effects of harmonics can be listed as; disruption of control devices, explode of capacitors, overload of transformations and additional losses in rotating machines, motors, and the occurrence of extra noise to motors and other elements, to cause telephone interference, parallel and serial resonance frequency. The most important and useful method of eliminating or reducing of harmonics is using harmonic filters. In this study, two different factory in the city of Van located at the east of the Turkey are examined in detail with a variety of different dates by Zera MT310's power analyzer measurements (instantaneous electrical values, harmonics, current and voltage waveforms, etc.). With these measurements, some power lacks of quality are determined and examined. After this process, single-tuned passive filter is designed by using Matlab/Simulink software for these factories.