Universal electronic load controller for microhydro power plant

Abstract

This Electronic load controller (ELC) has been an in-dispensary part of governor free Micro hydro plant for frequency control for a long period of time. Conventionally ELC consists of thyristor controlled dump load system; in which firing angle regulates the amount power to be fed into dump load. Such ELC units suffer many drawbacks, including injection to current harmonics, drawing high reactive current from the source, and so on. Further, the unbalance consumer load draws unequal current through the phases, and large current through neutral of the generator; thereby demanding the oversized generator. This study tries to address these issues by introducing a novel ELC. The proposed ELC system accommodate traditional active power filter (APF), STATCOM and dc chopper for compensating unbalance, harmonics and reactive power, irrespective of all loading conditions. It operates on instantaneous p-q based current injection method; by which harmonic, unbalance and reactive components are evaluated. Further, outer frequency control scheme is also applied to derive amount of active current fed to the ELC. These two current values are added to get the reference value of instantaneous for ELC. The system layout and control scheme are developed in Matlab® Simulink environment and different disturbance are introduced for dynamic response. The results shows that the ELC is functions well, by injecting the harmonics, unbalance and reactive components; which otherwise are to be supplied by the generator itself. Further the ELC is also capable of regulating frequency at designated value in spite of all loading condition. These result validates the propose scheme and a paves the way for its applicability in real system.