A high pulse naturally commutated static VAr compensator.
Thesis DisciplineElectrical Engineering
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
A new static VAr compensator (SVC) topology suitable for high voltage ac systems is proposed. This high pulse naturally commutated SVC is based on the ability of the ac/dc naturally commutated converter to regulate the absorption of reactive power and a novel method of achieving high pulse operation (i.e. with the dc ripple reinjection scheme). Steady state and dynamic operating performance of the scheme are tested in a variety of ac system conditions with the help of two models techniques, a scaled down equivalent in hardware and a high voltage representation in a computer simulation package (EMTDC-PSCAD). There is a linear relationship between firing angle and reactive current, and the 36-pulse harmonic characteristic of the compensator current is consistantly maintained over this operating range and in a variety of ac system conditions. Its dynamic performance is compared to that of the thyristor controlled reactor (TCR), when operating in the same power system environment, showing that the proposed scheme's voltage control ability is consistently faster than the TCR. The main difference in the compensator performances, however, is the proposed scheme's inherent temporary overload capability. This difference shows that there is the opportunity for the proposed scheme to supersede the TCR technology and further work to clarify the compensator's viability is considered to be worth while.