Advanced Static Var Compensators (ASVCs) use combinations of variable
inductive and capacitive elements with a switching converter to achieve faster
response to changes in ac system conditions - they have long replaced
traditional var compensators in mitigating the harmful effects of voltage
magnitude variations and low power factor in transmission and distribution
networks. In this paper an SVC configuration which has a 5-level voltage source
inverter (VSI) and minimum energy storage elements is investigated. This SVC is
usually referred to as advanced static var compensator (ASVC). 5-level inverter
is employed because of its high-power, high-voltage feature, and low-harmonic
content of the output voltage. The circuit model developed is used to
investigate the operation of the ASVC using the inverter phase angle δ as
control variable. The main aim of this work is to demonstrate the applicability
of this ASVC in power factor correction and voltage regulation improvement, and
hence improve the performance of transmission network. The equivalent circuit
of the ASVC was developed and applied to a system operating at 0.7 power
factor. Application of this ASVC achieved unity power factor in the system -
resulting in optimum voltage regulation (magnitude of receiving-end voltage
being very close to that of the sending-end voltage), decrease in power losses
(transmission loss in MW was reduced by 46.7% because the line current was
reduced from 3247A to 2370A) and costs. Consequently, the power transfer
capability of the line was enhanced. The Small reactive elements (L=9.54mH and
C=294 μF) were used to achieve these results. The simulations were done with
Matlab software.
