Analysis and design of output LC filter system for dynamic voltage restorer

Dynamic voltage restorer (DVR) has been demonstrated to be a very effective mechanism to deal with key voltage-quality disturbances. DVR is series connected in the power lines, and the LC filter is also series connected between the converter and grid. Appropriate design of LC output filter system not only could reduce the switching frequency harmonics, but also could maintain fast dynamic for low frequency, stability for control system, and high efficiency. This paper discusses the design issues of the output LC filter in DVR system and carries out the design in following aspects: 1) the parameter design of LC filter, which considering fundamental issue and cut-through frequency of LC filter; 2) the realization of virtual resistor, which uses damping method to solve the resonance problem; 3) the implementation of bypass switch, which consider the energy loss and efficiency. The design procedure is detailed presented in this paper and the validity is also demonstrated by the simulation.