Electricity and Control June 2025

Transformers, substations + the grid

Working together through a collaborative partnership, ACTOM, a leader in the field of energy infrastructure and electromechanical equipment, and Sungrow, a leading supplier of renewable energy and energy storage solutions, have developed the Integrated Medium Voltage Transformer and Inverter Station. Leigh Darroll, Editor of Electricity + Control spoke to Lee Mbenge, Divisional Chief Executive Oicer at ACTOM, about this innovation. Collaboration in action

initial prototypes entailed a significant learning curve. Although installations of this kind are in operation in China and in Europe, for ACTOM, the concept of the integrated transformer-inverter station was all new. The company has developed its own pad-mount transformer skids, which o”er a reference as mobile, plug and play units. However, incorporating a utility scale inverter into an integrated transformer-inverter unit introduces another dimension, and managing the unique dynamics of renewable energy, not least dealing with the volatile harmonics of renewables, also had to be considered. ACTOM embarked on an in-house process of development and testing, which took about five months. Mbenge outlines that testing itself involves first, an on paper assessment of the technology by the customer, then a factory and technical assessment of the manufacturing facility, and finally type testing of assembled units, for the respective application. At the time that Electricity + Control spoke to Mbenge, ACTOM was finalising another demonstration model to be exhibited at Enlit Africa 2025 in May.

Lee Mbenge, Divisional Chief Executive Officer at ACTOM.

P resenting a model of the Integrated Medium Voltage Transformer and Inverter Station, Mbenge points to the di”erent components that are packaged into a containerised utility-scale station, engineered specifically for use with renewable energy plants and intended to simplify and streamline installation and commissioning, as well as operations and maintenance. The 4.4 MW inverter, from Sungrow, is a modular assembly of four 1.1 MW inverters. It can be scaled up further, combining two by 4.4 MW inverters to provide an 8.8 MW inverter. The medium voltage transformer is supplied by ACTOM Power Transformers, engineered to accommodate the feed from a renewable energy plant via the inverter. The ring main unit (RMU), which manages the feed from the transformer to the transmission substation and in turn the grid, is third party supplied – in the case of the first prototypes developed it was supplied by ABB, China. The low voltage combiner box, which manages protection and control of the station, as well as communications with the overall energy management system of the respective installation site, is supplied also by Sungrow. Mbenge says Sungrow approached ACTOM to work with it, as a local partner, in developing this combined transformer-inverter station for a specific project. This was in response to a requirement for localisation from the client, as is standard for renewable energy projects developed by independent power producers in South Africa. Mbenge explains that initially, the intention was to deliver two of the transformer-inverter stations as ‘spares’ for the project. However, once they were installed, the client adopted them as primary equipment, in line with its own localisation objectives. Research & development Mbenge notes that as well as navigating the partnership arrangement with Sungrow, the development of the

An Integrated MV Transformer and Inverter Station in production at ACTOM Power Transformers.

24 Electricity + Control JUNE 2025