Application of least means square algorithm to shunt compensator: An experimental investigation

This paper discusses the simulation as well as hardware implementation results of a Distribution Static Compensator (DSTATCOM) for compensation of unbalanced loads and harmonic currents produced by nonlinear loads. The control scheme used for compensation is based on the fundamentals of adaptive filter theory. Least means square algorithm is one such scheme adopted here to extract fundamental and harmonic components of load currents. The decomposition of the load current is carried out by the learning algorithm. The control scheme for the voltage source converter (VSC) used as DSTATCOM is based on the fundamental currents extracted and the output of proportional-integral (PI) controller used for maintaining the dc bus voltage of the capacitor of VSC. The hardware implementation of DSTATCOM is performed using a digital processor-dSPACE DS1104 R&D controller having TMS320F240 as a slave DSP. Both MATLAB based simulation and hardware implementation results are presented for demonstrating the steady state as well as dynamic performances of DSTATCOM. The scheme is found to be effective in reducing the total harmonic distortion (THD) of supply current as per IEEE-519 standard.

I. Introduction

Load unbalancing, voltage regulation and poor power factor are some of the common power quality problems encountered in distribution systems [1]–[2]. Passive filters have been in use for a long time now. More recent solutions relate to custom power devices used in the distribution systems and flexible ac transmission systems (FACTS) devices [1]–[2]. Shunt compensators are used to solve power quality problems arising at the load end. The proliferation of nonlinear loads also injects harmonics into the point of common coupling (PCC), thereby affecting the performance of other interconnected loads. The use of shunt compensators for arc furnace and other rapidly fluctuating and highly nonlinear loads is now necessary for power quality improvement.