Development and implementation of a power quality controller for a mobilephone telecom station supplied by a rural utility end

Power quality problems in power distribution systems have been drawing more and more attentions these years, especially with the development of modern electronics industry. In practice a mobilephone station supplied by a rural utility end in North-West of China caught the author´s attention. Lots of power quality problems were found in the supply voltage. These power quality problems caused severe damages to the major equipment inside the mobilephone station building, including the off-the-line switching mode power supply for the telecom equipment and the air conditioner. As a solution, a series power quality controller (SPQC) was developed by the authors and installed to condition the power supplied to the mobilephone station. With three combined single-phase converters power stage, the SPQC provides multiple compensation functions including the filtering of voltage harmonics, regulation of voltage amplitude and frequency, and suppression of oscillations so that it could guarantee high quality power supplied to the mobilephone station. For practical purpose, a new control scheme was proposed and hereby introduced in this paper, in which two necessary complicated feedback control loops in regular control scheme are substituted by two coefficients and this scheme is quite easy to realize with advanced digital signal processor (DSP). The proposed control scheme is very simple, but quite effective and highly reliable. Plenty of laboratory experiments and field tests in the mobilephone station were conducted and verified the validity of the developed SPQC and the proposed control scheme. The SPQC with the proposed control scheme has already been put into practical operation successfully.