تعيين سهم هارمونيكي خطوط متصل به يك باسبار در شبكه هاي حلقوي به هم پيوسته

چكيده انگليسي :

117 Determining harmonic direction in interconnected mesh power system Mohammad Hadi Pourhoseini h pourhoseini@ec iut ac ir Date of Submission 2010 8 7 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan Iran 84156 83111 Degree M Sc Language Farsi Supervisors name Hamid Reza Karshenas karshen@cc iut ac ir Abstract Harmonic distortion is a power quality event that has recently received a lot of attention from both researchers and utility companies Harmonic distortion is on the rise due to the increased number of non linear loads like electric furnaces power electronic converters electronic ballasts and so on Harmonic distortion is the root of many problems in power system like overheating of transformers and electric motors damaging capacitor banks interference with telephone lines mal functioning of protection devices and reducing the capacity of transmission lines Furthermore the sensitivity of many loads to the harmonic distortion has also increased due to the use of delicate electronic and microprocessor devices in them Therefore many standards have been introduced and mandated in different countries in order to set limits for the level of harmonic pollution produced either by the utility customers as current harmonics or appear in the network as voltage harmonics In this regards it is important to recognize the source of harmonics in a network and find the contribution of customer utility in harmonic pollution This importance originates from the fact that standards have normally set some penalty for excessive harmonic pollution and thus in certain cases there may be some dispute between the utility and customers on who is responsible for the harmonic This dispute can be resolved by finding the direction of harmonics in the point under study Finding harmonic direction in distribution networks with radial configuration has been extensively considered in the literature but this issue has received less attention in the case of transmission systems with loop configuration In an interconnected power system harmonic pollution can move from one area to another area through transmission lines The direction of harmonic must be determined in power systems as one area may face large harmonic distortion without actually having substantial distorting loads In other words the direction of harmonics can also cause dispute in large power systems and therefore must be also calculated in transmission lines In this thesis the definition of harmonic direction both for current and voltage harmonics is clearly defined A well known method used to determine the direction of harmonics in a radial network is discussed This method is then modified and employed in transmission networks with loop configuration Therefore the direction of harmonics in transmission lines can be calculated and consequently the contribution of different areas in harmonic pollution can be identified The main approach in the proposed method is breaking the network with loop configuration down into a network with star configuration In doing so the transmission lines which cause loop configuration is broken down into two separate impedances referenced to the ground thus elimination the loop configuration After doing that the standard method for finding the harmonic direction in radial networks can be applied The studies are supported by a case study on a real power system Simulation of the network is performed in DIgSILENT software in order to calculate the harmonic impedance seen from different nodes Extensive measurements are done in the network to calculate the actual direction of harmonics Key Words Harmonic harmonic direction Mesh Power System Simulation Modeling

پورحسيني، محمد هادي

تعيين سهم هارمونيكي خطوط متصل به يك باسبار در شبكه هاي حلقوي به هم پيوسته

تعيين سهم , شبيه سازي