VOL. 6, NO. 11, NOVEMBER 2011 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences © 2006-2011 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com A NOVEL TECHNIQUE FOR THE LOCATION OF FAULT ON A HVDC TRANSMISSION LINE A. Swetha, P. Krishna Murthy, N. Sujatha and Y. Kiran Department of Electrical and Electronics Engineering, Swarna Bharathi Institute of Science and Technology, Khammam, A.P. India E-Mail: krishnamurthy.pannala@gmail.com ABSTRACT This paper presents Mathematical Morphological applications to assess the performance of High Voltage Direct Current system. The satisfactory performance of this system is one of the necessary conditions to obtain uninterrupted power supply as it is transmitting bulk power over a long distance. In this paper a 300 kM long HVDC system is simulated for various faults on the DC line and a technique to locate the faults on the DC line is proposed. The simulated results presented in this paper are in good agreement with the published work. Keywords: HVDC transmission, fault location, mathematical morphology, structuring element. INTRODUCTION The industrial growth of a nation demands increased consumption of energy, particularly electrical energy. Generation of electrical energy at increased levels needs to be supported with efficient power transmission system which is capable of transmitting bulk power over long distances with minimum operational losses. Due to rapid technical advancement in power electronics the HVDC transmission has become very efficient means of transferring power in bulk over long distances. Hence, the reliability of HVDC systems has always been of the prime concern in planning and operation of power systems. The long HVDC line cannot be modeled sufficiently with lumped parameters as is done in the conventional AC protection systems. Therefore in the principle and protection criteria of the long HVDC lines, the lines are represented as distributed elements. In AC line faults, the amplitude of the travelling wave generated due to the occurrence of the fault changes with the phase angles. It is more difficult to judge by using travelling waves when the fault occurs near the voltage crossing zero. However, there is no such problem for DC lines; hence traveling wave protection ideally suites for the detection of faults on HVDC line [1]. The main focus of this paper is to apply Mathematical Morphology for analyzing the HVDC system faults. Digital Signal Processing is distinguished from other areas in computer science by the unique type of data it uses: signals. In most cases, these signals originate as sensory data from the real world like seismic vibrations, visual images and sound waves. DSP is the mathematics, the algorithm, and the technique used to manipulate these signals after they have been converted into a digital form. This includes a wide variety of goals, such as: enhancement of visual images, recognition and generation of speech, compression of data for storage and transmission [2]. Implementation of Mathematical Morphology (MM) requires a set of rudiments defined by a Structuring Element (SE) that is used to process a given signal. A structure element is the smallest part of a structure which when connected to other structure elements makes up a continuum, a boundary or a support of that structure. Selection of SE is to be done appropriately, often by trial and error, since the quality of MM output depends upon it [3]. In this paper a novel technique based on Mathematical Morphology is used to analyze a signal generated from the HVDC transmission system during various operating conditions. SIMULATION MODEL A standard 12 pulse HVDC system under the MATLAB environment is used for the analysis and simulation (Figure-1). The simulation model is a 1000 MW (500Kv, 2KAmp) DC line is proposed to transmit power over a 300 km transmitter line from a 500 Kv, 5000MVA, 60Hz network to a 345Kv, 10,000MVA and 60Hz Network. HVDC system is designed to acquire data at a sampling frequency of 80 kHz. The HVDC system model has been simulated for DC line fault. The DC line data is recorded at the rectifier side and is used for the analysis. The data recorded from the rectifier side has been used to calculate the voltage magnitude of the Reverse Voltage Travelling Wave (RVTW). The RVTW has been used for the analysis and location of faults on the system. The calculated RVTW of the transmission line has been analyzed using Signal Processing method. 62