NamPower engineers finds remedy for faulty Walvis Bay Substation Transformers
By Clifton Movirongo.
Power utility, Nampower has revealed that its engineers and technicians were instrumental and contributory in finding a remedy for the ever-malfunctioning transformers at the Walvis Bay Substation in the Erongo region.
The discovery was made by the Protection, Telecommunication, Metering & Control (PTM&C) team, which designed, tested, and successfully implemented a simple, but reliable Automatic Voltage Regulation (AVR) solution for the coastal town’s substation transformers.
“They discovered a potential solution involving the functional extension of the already-installed SEL 2411 transformer monitoring device to implement voltage monitoring and on-load tap changer control,” NamPower said in a statement.
The company detailed that the device regulates and keeps the voltage on the load side within an acceptable margin, while it also ensures equal transformer loading during parallel operation and blocks tap changer operation under abnormal and system fault conditions to prolong the lives of transformers.
This comes after three years after its commissioning in 2016, the AVR devices, with which the transformers were equipped started malfunctioning and failing. According to NamPower, these failures were not only observed at the Walvis Bay substation but also at other substations namely Okapya and Kuiseb.
“During the period 2020 to 2021, at the Walvis Bay substation alone, more than five units were replaced due to failure and sent for repairs. However, even the replaced units began failing after a few months of installation,” added the power utility.
The power utility has also maintained that the Walvis Bay substation is a very important station, as it has a three-fold role in the region with its heavy energy-consuming industries such as mining, fishing, and tourism, among others. “The substation is essential in supplying a wide range of electrical loads in the residential, commercial, and industrial sectors in and around the town of Walvis Bay. It also provides auxiliary power supply to the ANIXAS and Paratus Power Stations.”
Meanwhile, according to NamPower, the major problem was the lengthy turnaround time of repair, which takes almost a year, thereby leaving the burden on power system controllers and operators to manually monitor and regulate the voltages of these transformers in the Walvis Bay substation and other sites.
The device has high reliability and is very cost-effective, as the solution costs NamPower about N$ 4 500 per device as the engineers had to procure, install, and programme a three-phase voltage input card into the SEL2411 relays, while previously it would cost the power utility approximately N$ 50 000 per device repaired, they added.
“Despite this being the first installation, it took engineers four days to implement and commission this solution on three transformers. This has not only resolved the persistent failure of the initially installed tapcon AVRs but could also serve as a benchmark for future AVR solutions on most of NamPower transformers.”