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Modelling and analysis of a HVDC light system
2002 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

This Master's Thesis deals with modeling and analysis of a HVDC-Light (High Voltage Direct Current) system in the frequency domain. The models for simulation have been built in Matlab/Simulink using the PSB (Power System Blockset) components. Methods of analysis from the general automatic control theory are used. The HVDC Light is a new power transmission technology developed by ABB. This technology is used to transmit electricity over long distances and to interconnect unsynchronous power system, where traditional AC links can not be used. To simulate and analyze the dynamical characteristics of the HVDC systems, it is necessary to have models both in the time domain and in the frequency domain. The closed loop simulation models include the compiled code of the control system MACH2 that is used in the real system. This code is linked to the simulink models by using a S-function. Finding the transfer functions of the system, a frequency domain analysis was done. The method of transforming three coordinates to two coordinates is used in order to find the transfer functions for the active and reactive power. A direct method to find de transfer functions for active and reactive power in three phase systems is proposed. Models that include a simplified PI controler and the control system MACH2 have been simulated and analyzed. Discretization of the system gives shorter simulation time without losing accuracy. The results of the simulation show how the switching affect the step response. The analysis of the transfer functions shows the stability margins and resonance frequencies. Throughout the work, Matlab was evaluated as a simulation and analysis tool. Its possibilities and problems were recorded.

Place, publisher, year, edition, pages
Keyword [en]
Technology, HVDC modelling, HVDC transfer functions, Voltage source, converter, frequency response, HVDC control
Keyword [sv]
URN: urn:nbn:se:ltu:diva-47323ISRN: LTU-EX--02/307--SELocal ID: 4e0e880c-90cf-4490-967d-39557f0eb2efOAI: diva2:1020643
Subject / course
Student thesis, at least 30 credits
Educational program
Electrical Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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