Defining and Specifying Design Considerations for Distribution Transformers in Large-Scale Solar Photovoltaic Plants

Abstract

In the new era of the renewable energy market in South Africa, there is a knowledge gap in the technical standards relating to distribution transformers, which are exclusively intended to serve in large-scale solar photovoltaic (PV) applications. The problem arises from the reality that these transformers are compelled to facilitate an environment with a potentially high risk of an unacceptable level of harmonics and distortion. What manufacturers currently need is a comprehensive transformer specification for DT transformers in PV applications, as the standards currently in use for regular transformers have so far proven to be inadequate. The latter triggers the need for this work to contribute to the advancement of this knowledge gap by mapping a comparative analysis of defining and specifying the design considerations for solar PV transformers. Initially, the computation of the various transformer losses at multifaceted active-part structures under normal conditions by employing the proposed finite element analysis (FEA) is presented. Then, two design case studies are described and the harmonic load current content to which the transformer will be susceptible during operation is specified and used for the analysis. Lastly, the design losses computed using the proposed FEA are substantiated using practical measurements.