Control strategy of DVR with a positive and negative sequence extraction method

This paper presents a new compensation strategy based on instantaneous reactive power theory which can be used in the Dynamic Voltage Restorer (DVR). This strategy uses multiple DQ transformation with separation modules to extract the positive and negative sequence components from fundamental and harmonic waves, so as to analyze and adjust each component separately. As a result o f this new strategy, the dynamic response and the tracking accuracy are improved and the fluctuations of DQ components are decayed. To verify its effectiveness, a cascade DVR simulation model has been built in MATLAB/SINMIJLINK and a series o f simulations have been carried out. The results of transient and steady state show that the DVR is competent to make a better compensation with this new strategy in the case o f complex conditions such as sags, harmonics and unbalances. The control strategy is tested by a 10kV/500kVA voltage drop generator test rig, and the experimental results validate that the strategy can provide improved dynamic response and high accuracy in both dynamic and steady states. The strategy has tremendous engineering applications.