Application of Shunt Active Power Filter for Dynamic Compensation of Reactive Power & Harmonics for 12-pulse Converter Power Supply of Tokamak Superconducting Coils

Abstract

AC/DC Converters Power Supplyof a Tokamak machine (for the Toroidal Field (TF) and Poloidal Field(PF)
superconducting magnet coils) draws significant inductive reactive power from the AC supply system and also produces
harmonics in the supply AC Currents. The quantum of reactive power demand and the current harmonics produced varies
dynamically, depending on various system parameters, like load current of each magnet coil, quality of AC supply voltage,
inductance of magnet coils etc.
Fixed compensation solutions, e.g. passive filters, are not suitable for the subject application, as they may result in
over/under compensation. Also, other solutions like SVC, FC-TCRs etc require passive components like capacitors or
inductors, which have short service life. The Shunt Active Power Filter (SAPF) with comparatively smaller size capacitors &
inductors can provide the same level of compensation and have a faster response to load changes.
In this paper, the modeling&simulation of AC/DC Converter Power Supply System of a typical Tokamak machine has been
described, to determine the Reactive Power demand & Harmonics produced at the PCC. Then the modeling & simulation of
Shunt Active Power Filter (SAPF), based on Instantaneous Reactive Power Theory(p-q Theory) has been described. The
performance of the SAPF under unbalanced & distorted supply voltage conditions has also been evaluated.