Resumo:
The aim of this thesis is to present the option of application of the capacitor
commutated converter CCC in HVDC transmission systems, which present same
advantages comparatively with the conventional HVDC systems that don’t use the
series compensation employing capacitors in the converter alternating current, AC
side.
The capacitors propitiate the supply of reactive power to the converter and
also are favorable to minimize the inverter commutation failures due to the
increasing of the commutation margin and also due to the voltage compensation,
when a system voltage drop occurs. These aspects result favorable with respect to
the increasing of the stability of the system which uses this proposed arrangement
of series compensation system, using capacitors.
Experimental relevant current and voltage waveforms for the six pulse
conventional converter was obtained for the comparison with the results obtained
when the case of using the CCC converter. Simulated results are also presented
for the 12 pulse converter, which is obtained by associating in series two six pulse
ones. Digital simulation programs have also been developed for obtaining the
relevant conventional and CCC converter waveforms, as well as for obtaining the
iterative calculation of the commutation angle.
On this way a comparison of simulated and experimental results will be
possible for validation of the developed digital programs for obtaining the relevant
converter current and voltage waveforms and also for the calculation of the
commutation angle. The main advantages and disadvantages of the CCC HVDC
systems, compared with the conventional ones, are presented.
