Virtual Oscillator Control of Distributed Power Filters for Selective Ripple Attenuation in DC Systems

摘要

In this article, a decentralized controller, based on the current mode virtual oscillator, is proposed to control the distributed power filters in dc systems. This communication-free solution only requires local dc bus voltage measurements as its control input. With the proposed control algorithm, the power filters can automatically share the target ripples based on their storage capacities, realizing modular and fault tolerant design. One typical application is that they can be placed on the dc subgrid of a hybrid ac/dc microgrid to attenuate the second-order harmonics from ac side. A frequency adaption mechanism is further embedded within the controller; hence, it can process any ripples at an unknown frequency for more general applications. To eliminate the circulating current caused by the power line dynamics, virtual impedance is employed to modify the feedback voltage measurement of the virtual oscillator. The proposed control algorithm has been verified by both simulation and down-scaled experiments.