Direct active and reactive power regulation of grid connected voltage source converters using sliding mode control approach

This paper presents a new direct active and reactive power control (DPC) of three-phase grid connected voltage source converters (VSCs). The proposed DPC strategy employs a nonlinear sliding mode control scheme to directly calculate the required converter voltage so as to eliminate the active and reactive power errors without involving any synchronous coordinate transformations. Besides, no extra current control loops are required, thereby simplifying the system design and enhancing the transient performance. Constant converter switching frequency is achieved by using space vector modulation (SVM) which eases the design of the ac harmonic filter. Simulated results on a 100kVA grid connected VSC system are provided and compared with those of classic voltage-oriented vector control (VC) and conventional look-up-table (LUT) DPC. The proposed DPC provides enhanced transient performance similar to the LUT DPC and keeps the steady-state harmonic spectra at the same level as the VC.