Reduced Component Count UPQC Configuration with Integrated Distribution Transformer

Abstract

Power quality has become an important aspect in power systems and has gained interest in recent years. Two main factors influence this: first, the widespread use of power electronics based equipment have increased harmonic levels in power systems, which have a negative impact on various power system components, such as transformers. Second, the use of sophisticated equipment which are sensitive to voltage quality have become commonly used where a malfunction can lead to significant financial losses. Improving power quality can solve these issues while improving the efficiency of power systems. On the transmission level, Flexible AC transmission system (FACTS) devices are being used to improve transient stability, enhance power transfer capacity, and reduce transmission line losses. Alternatively, in the distribution level, Unified Power Quality Conditioner (UPQC) is a versatile device to enhance power quality on a smaller scale. UPQC is a power electronic based device that can correct voltage and current related power quality issues simultaneously. Current related power quality issues such as current harmonics, unbalance, and power factor can be corrected so that the power system only delivers active power the connected loads. Whereas, voltage related problems like voltage sag, swell, unbalance, and harmonics can be compensated such that loads connected to the system are not affected by these transients. Due to their versatility, UPQC is a topic of research interest in which research has been carried out to improve performance, efficiency, and reduce cost. Various UPQC topologies have been introduced in an effort to reduce the overall while maintaining its performance and efficiency. A reduction in the number of components can lead to a reduction in the cost of a UPQC. Series injection transformer-less (SITL) UPQC are an example of a reduced component count UPQC. In this thesis, an SITL UPQC is introduced and its construction in addition to its mode of operation is explained. The advantages of SITL, compared to a conventional UPQC, are also elaborated along with the challenges faced due to its construction. In this thesis a control method for 3P4W SITL UPQC is proposed. The proposed approach allows easy realization of virtual neutral point so that single phase loads can be connected. A Matlab/Simulink based simulation model is developed for the SITL-UPQC system. The performance of the proposed approach is validated through simulation study under different operating conditions.

Date of Award	May 2017
Original language	American English
Supervisor	Vinod Khadkikar (Supervisor)