Improvement of Power Quality in Transmission System by Hybrid Power Flow Controller (HPFC)

Abstract

The demand of electrical energy is rising across the world. But with that, installation of new generation or
transmission system is the matters, constrained by economical and environmental factors. The alternative is to utilize the
maximum capacity of existing system by some means. FACTS provides avenue to utilize the maximum capacity of existing
system without endangering the stability, security, and performance of system, thus providing efficient utilization of
existing system. UPFC is the most versatile FACTS device, which have the best performance characteristics in
comparison to other classical controllers. But UPFC is very costly controller because of its configuration, consists of two
VSCs. And the topology used in UPFC does not allow it to retrofit the existing equipment like switched capacitor, SVC,
TCSC etc. This paper discusses the applicability of “Hybrid Power Flow Controller” (HPFC) as a cost effective and
performance equivalent alternative of UPFC. In this paper, two topologies of HPFC are evaluated. Both topologies
consist of a reactive power compensator and two VSCs. UPFC is a FACTS device consisting two converters, one is in
series and one is in shunt with the line. In first topology of HPFC, the shunt converter of UPFC is substituted by a
(presumably existing) switched capacitor, while its series converter is split into two “half sized” ones, installed on each
side of the shunt device. And in second topology of HPFC, one of the switching converters of the UPFC is replaced by
thyristor controlled variable impedance and other converter of UPFC is split into two “half sized” ones, installed on each
side of the series device. Such topological arrangement results in operating characteristics similar to those of the UPFC,
while achieving considerable savings in the total required converter MVA ratings.