A local transformer manufacturing facility has supplied 36 specialised photovoltaic (PV) transformers to a solar energy generation plant in the Northern Cape.

Conventional distribution transformers are not adequate for renewable energy applications and distribution photovoltaic (DPV) solar energy transformers and generator step-up (GSU) wind turbine transformers have had to be specially designed for these projects.

The transformers were supplied by Zest WEG’s local transformer manufacturing facility, heralding the company’s entry into the local production of transformers for the renewable energy sector.

The design was reviewed by an international independent consultant and the dual-system PV transformers were manufactured to the customer’s specification of 3800/1900-1900 kVA and 22/0.66-0.66 kV. The units were also subject to routine and type testing, including heat run, impulse and partial discharge tests.

The company affirms that it sees great potential in the future of renewable energy solutions in Africa, creating new demands and challenges for transformer design.

Among the specific factors affecting transformers in DPV power generation systems is solar irradiation, which affects the load profile and thermal stress in the transformer materials.

According to Zest WEG , transient overvoltage is also an issue to consider. On the high voltage (HV) side, overvoltage transients may occur owing to multi-stage capacitor banks switching, or from the circuit breaker operation. On the low voltage (LV) side, voltages are controlled with high frequency inverters which create harmonics and pulsed voltages.

An electrostatic ground shield is required between the primary and secondary windings to eliminate capacitive coupling and transient overvoltage transfers, which also filters harmonics of high frequencies and pulsed LV voltages, explains the company.

In addition to the local design and manufacture of transformers for renewable energy projects, the company provides a range of integrated solutions for these projects. These include substations, e-houses, switchgear and inverters.