Fully Decou pled Controller Models for Voltage Source Converter based High Voltage DC Transmission

• Main Author: Ahmed Mahjoub, Ahmed Mahjoub
• Format: Thesis
• Language: English
• Published: 2009
• Subjects: TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://utpedia.utp.edu.my/8759/1/2009%20-%20Fully%20Decoupled%20Controller%20Model%20for%20Voltage%20Source%20Converter%20Based%20High%20Voltage%20DC%20Transm.pdf; http://utpedia.utp.edu.my/8759/

VSC-HVDC has two distinct advantages over its earlier generation thyristor based High Voltage DC transmission. Synchronous voltage source is not required to commutate against, for its operation and it does not suffer from commutation failures under adverse conditions in interfacing ac system. These two properties make it amenable to wider application areas. To make it adapt to operational conditions imposed on it in various applications, its controller parameters need to be assessed and tuned through extensive simulation studies. To facilitate this, two alternative controllers viz. a fully decoupled controller model and also an instantaneous theory based fully decoupled hybrid controller model are developed in the thesis. The decoupling is achieved by exploiting similarity transformation in both the controllers. In the first controller model, the Park's currents and voltages are directly obtained from the measured network variables and the reference park's currents for the inner current loop are obtained from the instantaneous measured power. In the second one, both the feedback as well as reference Park's currents for the inner current loop are obtained from the Clarke's variables. An AC system interfacing electronics based power transmission or distribution network experiences non-sinusoidal voltage and current waveforms. Instantaneous power theory being suitable for steady as well as transient states, is used for handling measured inputs. The performance of the models is assessed through SIMULINK Power system Blockset aided simulations on a VSC-HVDC link interfacing an ac system, having normal fault level, low fault level and also witnessing a single line to ground fault on its rectifier transformer primary side.