Modulation and Control of Transformerless UPFC

Abstract

In this paper, a modulation and control method for the new transformer-less unified power flow controller (UPFC) is presented. As is well known, the conventional UPFC that consists of two back-toback inverters requires bulky and often complicated zigzag transformers for isolation and reaching high power rating with desired voltage waveforms. To overcome this problem, a completely transformer-less UPFC based on an innovative configuration of two cascade multilevel inverters (CMIs) has been proposed. The new UPFC offers several advantages over the traditional technology, such as transformer-less, light weight, high efficiency, low cost and fast dynamic response. This paper focuses on the modulation and control for this new transformer-less UPFC, including optimized fundamental frequency modulation (FFM) for low total harmonic distortion (THD) and high efficiency, independent active and reactive power control over the transmission line, dc-link voltage balance control, etc. The new UPFC with proposed control method is verified by experiments based on 4160 V test setup. Both the steady-state and dynamicresponse results will be shown in this paper.Index Terms-Flexible ac transmission systems (FACTS), unified power flow controller (UPFC), transformer-less, multilevel inverter, power flow control.

Unified Power Flow Controller Based on Autotransformer Structure

“…In contrast, the parallel inverter compensates the reactive power and supplies the power required for the series inverter. However, the series transformer and inverter are bulky and expensive because a large amount of transmission-line current flows through them [23]. Therefore, the use of conventional UPFCs has been limited, although their performance is outstanding.…”

Fuzzy Second Order Sliding Mode Control of a Unified Power Flow Controller

“…Unified power flow controller (UPFC) is the member of FACTS device. It is the most versatile and powerful FACTS device [3]. The fundamental theory of UPFC is that, the phase angle affects flow of real power and the magnitude of voltage affects flow of reactive power [4,5].…”

An energy harvesting and damage sensing solution based on postbuckling response of nonuniform cross‐section beams

“…Yet vibration‐based piezoelectric harvesters deliver optimal performance only when excited near their resonance frequency. In order to widen the input requirement and extend the application range, many research efforts have been conducted to enlarge the operating bandwidth of vibration‐based piezoelectric generators . However, these approaches are still inefficient for low‐frequency applications, particularly within the quasistatic domain (<1 Hz).…”

“…In order to widen the input requirement and extend the application range, many research efforts have been conducted to enlarge the operating bandwidth of vibration-based piezoelectric generators. [20][21][22][23][24][25] However, these approaches are still inefficient for low-frequency applications, particularly within the quasistatic domain (<1 Hz). On the other hand, buckling and postbuckling elastic instabilities have been extensively studied with multiple functional purposes.…”