International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 5, May 2014) 132 Harmonic Analysis in HVDC System Anuradha.V 1 , Anitha.S 2 , Apoorva.D.C 3 , Priyanka.N 4, Somashekar.B 5 1, 2, 3, 4 Student, B.E, EEE, Dr. T. Thimmaiah Institute of Technology, K.G.F 5 M.Tech, Lecturer, EEE, Dr. T. Thimmaiah Institute of Technology, K.G.F. Abstract— Harmonics are electric voltages and currents that appear on the electric power system as a result of non- linear electric loads. Non-linear loads include common office equipment such as computers and printers, Fluorescent lighting, battery chargers and also variable speed drives. Harmonic components should be reduced as much as possible. According to harmonic stability problem that was caused by the non-linear of converter, the simulation model was established based on the actual equipment situation of convert station. Harmonic instability may occur in high-voltage dc (HVDC) links due to dynamic interactions between HVDC terminals and the impedance of the dc lines or cables. In recent years, the issue of harmonics compensation has got considerable attention. The main purpose of this paper is to reduce the harmonics in transmission of power in HVDC system. THD values can be calculated using FFT analysis. Simulation model is developed in MATLAB/Simulink environment. Keywords— HVDC, harmonics, filters, rectifier, inverter, active filters, passive filters I. INTRODUCTION The semiconductor devices in DC converter station is a non-linear power electronic device. A large amounts of characteristic and of non-characteristic harmonics currents will be produced and injected into the AC power system when the HVDC running even the supply voltage waveform of AC side is the standard sinusoidal wave and cause voltage distortion and because of the asymmetric of the three-phase AC systems respectively. The harmonics that come from the HVDC will not only increase loss, thermal stress of equipment, reduce equipment life, interference with communications, metering, protection and control devices to work properly and in some cases, it can even lead to the collapse of the system. Harmonics are electric voltages and currents that appear on the electric power system as a result of non-linear electric loads. Harmonic frequencies in the power grid are a frequent cause of power quality problems. Harmonic components should be reduced as much as possible. There are two types of harmonics in electrical power systems, namely current harmonics and voltage harmonics, which are distortions to current and voltage waves respectively. On the basis of generation, there are two types of harmonics-characteristic and non-characteristic. One of the major effects of power system harmonics is to increase the current in the system. This is particularly the case for the third harmonic, which causes a sharp increase in the zero sequence current, and therefore increases the current in the neutral conductor. This effect can require special consideration in the design of an electric system to serve non-linear loads. The presence of harmonics leads to low system efficiency, poor power factor, increased loss and reactive power components from AC and also on the equipment present in the system and interference on the telecommunication lines. There were many methods used for the analysis of harmonics in a LCC (Line Commutated Converter) HVDC system. Some of them are – Symmetrical component method, individual phase control, harmonic mapping, Eigen value analysis, numerical methods, etc. But each of the methods had limitations, thus, impedance model is sorted as a better analysis method for harmonics in a LCC- based HVDC system. Basically for reduction of harmonics, filters are used. Here we use a hybrid configuration of both passive and active filters for improved power handling capacity of semiconductor devices and better performance. Fig.i Block representation of HVDC system II. SYSTEM MODELLING In general, the AC power grid structure of AC-side in converter station is very complex. For the equipment that is inside the converter station, such as high-voltage bus, converter transformers, converter valves etc. were simulated using detailed models the DC line model is the sub-T-Line model. The simulation and the parameters were in strict accordance with the field. The corresponding calculation/design of the parameters is as given below-
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Harmonic Analysis in HVDC System - Semantic …...considering a single pole HVDC terminal at POWERGRID, KOLAR (2000MW-bipole +_500KV) converter station in located in Karnataka. According
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International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 5, May 2014)
132
Harmonic Analysis in HVDC System Anuradha.V
1, Anitha.S
2, Apoorva.D.C
3, Priyanka.N
4, Somashekar.B
5
1, 2, 3, 4Student, B.E, EEE, Dr. T. Thimmaiah Institute of Technology, K.G.F
5M.Tech, Lecturer, EEE, Dr. T. Thimmaiah Institute of Technology, K.G.F.
Abstract— Harmonics are electric voltages and currents
that appear on the electric power system as a result of non-
linear electric loads. Non-linear loads include common office
equipment such as computers and printers, Fluorescent
lighting, battery chargers and also variable speed drives.
Harmonic components should be reduced as much as possible.
According to harmonic stability problem that was caused by
the non-linear of converter, the simulation model was
established based on the actual equipment situation of convert
station. Harmonic instability may occur in high-voltage dc
(HVDC) links due to dynamic interactions between HVDC
terminals and the impedance of the dc lines or cables. In
recent years, the issue of harmonics compensation has got
considerable attention. The main purpose of this paper is to
reduce the harmonics in transmission of power in HVDC
system. THD values can be calculated using FFT analysis.