Date of Graduation


Document Type


Degree Name

Master of Science in Electrical Engineering (MSEE)

Degree Level



Electrical Engineering


Juan C. Balda

Committee Member

Alan Mantooth

Second Committee Member

Roy McCann


Applied sciences, Electric distribution systems, Negative-sequence currents, Shunt compensator, Unbalanced compensation, Zero-sequence currents


The objective of this thesis is to present the theory, design, construction, and testing of a proposed solution to unbalanced current loading on three-phase four-wire systems. The Unbalanced Current Static Compensator is the name of the prototype; herein referred to as the UCSC. The purpose of this prototype is to redistribute current between the three phases of a distribution system. Through this redistribution, negative- and zero-sequence currents are eliminated and a balanced system is seen upstream from the point of installation.

The UCSC consists of three separate single-phase H-bridge inverters that all share the same dc-link capacitor. Each of these inverters performs independently using a single-phase rotating reference frame controller. Each either draws or injects current onto the distribution system lines to balance the active currents and performs power factor correction for voltage compensation. A 34.5 kV, 6 MVA system was built and simulated in Matlab/Simulink™ to test the validity of this solution. A scaled-down UCSC prototype was then designed and constructed to compensate for a 208 V, 10 kVA system. Results from both the simulations and testing of this UCSC prototype are presented and analyzed.