Operation of Direct Power Control Scheme in Grid-Connected Mode Using Improved Sliding Mode Observer and Controller

This paper introduces the direct power control (DPC) scheme controlled by a new version of the 1st order sliding mode control to operate a distributed generator. This distributed generator is a core of the distributed generation system (DGS), which injects active and reactive power to the distribution system in a grid-connected mode. The presented 1st order sliding mode control based direct power scheme is very efficient in terms of chattering at steady-state and its dynamic performance. The superior performance of the presented control scheme results from a novel combination of an integral form for the sliding surface along with an innovative power-rate reaching law. The feedback power of the direct power scheme is estimated using an accurate developed formulation of the sliding mode observer. The distributed generator is based on the 5-level diode clamped inverter to minimize the injected harmonics. To prove the accurate performance of this new combination of the sliding mode control with sliding mode observer, the developed sliding mode observer is compared to Luenberger observer and the traditional virtual-flux based power estimation. Also, the whole control scheme is compared to other schemes for the same application such as conventional direct power control and conventional sliding mode control based direct power control.