S. Bhattacharya et al., HYBRID SOLUTIONS FOR IMPROVING PASSIVE FILTER PERFORMANCE IN HIGH-POWER APPLICATIONS, IEEE transactions on industry applications, 33(3), 1997, pp. 732-747
This paper presents a new control scheme for a parallel hybrid active
filter system intended for harmonic compensation of large nonlinear lo
ads up to 50 MVA, to meet IEEE 519 recommended harmonic standards, The
active filter is small rated, 2%-3% of load kilovoltampere rating, Th
e control scheme is based on the concept of synthesizing a dynamically
variable inductance, and its usefulness is demonstrated for an active
filtering application, A synchronous reference frame (SRF) controller
implements the dynamically varying negative or positive inductance by
generating active filter inverter voltage commands, This variable ind
uctance controller parallel hybrid active filter system can selectivel
y synthesize multiple ''active inductances'' at dominant harmonic freq
uencies without affecting passive filter impedances at all other frequ
encies, This controller also provides a ''current limiting'' function
to prevent passive filter overloading under ambient harmonic loads and
/or supply voltage distortions, Three implementation variations of a p
arallel hybrid active filter system are presented, This paper also pro
poses the use of power factor correction capacitors as low cost passiv
e filters for a parallel hybrid active filter system, which are contro
lled to provide either single or multiple tuned harmonic sinks and to
increase cost effectiveness for high power applications, Simulation re
sults with small rated pulsewidth modulated (PWM) and square-wave acti
ve filter inverters validate the proposed variable inductance controll
er operation for mistuned passive filters, to provide single and multi
ple frequency tuning to achieve harmonic compensation of a 325 kVA har
monic load under supply voltage harmonics and ambient harmonic loads.