Page 275 - Power Electronic Control in Electrical Systems
P. 275
//SYS21/F:/PEC/REVISES_10-11-01/075065126-CH007.3D ± 263 ± [263±289/27] 17.11.2001 10:24AM
7
Harmonic studies of
power compensating
plant
7.1 Introduction
The use of power electronics-based equipment in high-voltage power transmission
and in low-voltage distribution has increased steadily over the last three decades.
Notwithstanding their great many operational benefits, they also have increased the
risk of introducing harmonic distortion in the power system because several of these
devices achieve their main operating state at the expense of generating harmonic
currents. In the early days, most applications of this technology were in the area of
HVDC transmission (Arrillaga, 1999). However, the SVC which is a more recent
development, has found widespread use in the area of reactive power management
and control (Miller, 1982). In the last 20 years or so, a substantial number of SVCs
have been incorporated into existing AC transmission systems (Erinmez, 1986;
Gyugyi, 1988). Many utilities worldwide now consider the deployment of the newest
and most advanced generation of power electronics-based plant components,
FACTS and Custom Power equipment (Hingorani, 1993; 1995), a real alternative
to traditional equipment based on electromechanical technologies (IEEE/CIGRE,
1995).
Over the years, many adverse technical and economic problems have been traced
to the existence of harmonic distortion. Professional bodies have long recognized
harmonics as a potential threat to continuity of supply and have issued guidelines on
permissible levels of harmonic distortion (IEEE IAS/PES, 1993). However, it is
generally accepted that this problem, if left unchecked, could get worse. Hence, great
many efforts are being directed at finding new measuring, simulation and cancella-
tion techniques that could help to contain harmonic distortion within limits. Sub-
stantial progress has been made in the development of accurate instrumentation to
monitor the harmonic behaviour of the network at the point of measurement
(Arrillaga et al., 2000). However, in planning and systems analysis the problem must