Plug-and-play AC/AC power electronics building blocks (AC-PEBBs) for grid control

Abstract

As ac-to-ac power conversion becomes increasingly importantly in applications such as grid power flow control and motor control, the demand for a plug-and-play converter is increased. Traditional VSI-based ac-to-ac power converters such as the back-to-back converter require bulky dc-link capacitors that limit their reliability. Therefore, approaches that offer direct ac-to-ac power conversion are gaining popularity. This paper proposes a plug-and-play concept for achieving ac-to-ac power conversion via the ac/ac power electronic building block (AC-PEBB). The AC-PEBB is a compact, self-contained cell requiring no energy storage. It can be used in a variety of direct ac/ac converters including matrix converters, controllable network transformers (CNT), etc. This paper details the construction of a prototype AC-PEBB to be used in a 13 kV, 1 MVA application. The effectiveness of the AC-PEBB is demonstrated experimentally in an example application of controlling grid power flows via a 10 kVA CNT prototype built by augmenting a standard transformer with a single AC-PEBB cell. Series and parallel connection of multiple AC-PEBBs to increase maximum voltage and current handling capability is also demonstrated.