Active Resonance Dampers: A comparison between fixed and adaptive gains

This work presents a comparison between two control strategies for Active Resonance Dampers. This kind of equipment must act as a harmonic impedance in order to damp harmonic propagation throughout a distribution feeder. This harmonic resistance must be equal to the characteristic impedance of the distribution feeder in order to achieve optimized compensating currents and avoid over-compensate the feeder (which may amplify distortion on intermediary buses). As the analytical calculation of this impedance is a non-trivial (and maybe, impossible) task, it is proposed an ARIMAX Least-Squares based parameters estimator to determine, on line, the optimal value for the harmonic resistance. The system is modeled in a way that allows the feeder´s characteristic impedance to be estimated based only on the installation site voltage (i.e., no voltage/current sensors are required on other parts of the feeder) independently on the number of buses or non-linear loads attached to them. A sliding-Goertzel algorithm is used to extract the harmonic content of the installation site voltage (thus, no PLL or d-q transforms are necessary, making the algorithm suitable for single phase systems). The proposed strategy (estimated impedance) is, then, compared with the traditional one (fixed impedance) through simulations.