Slovenia has been providing its neighbor, Italy, with power since 2010. The phase shifter transformers (PSTs) of Slovenian grid operator ELES control the flow of powerful electrical loads between the countries, thus guaranteeing the safe, reliable interruption-free transfer or exchange of electricity. As Aleksander Polajner, Head of the High Voltage Device department at ELES, explains. "In the event of an unplanned failure, in the worst-case scenario, our lights or our neighbor’s lights go out."
Retrofit: Bushing monitoring for phase shifters
Bushings are one of the most important parts of the transformer. That is why Slovenian grid operator ELES relies on the MSENSE® BM monitoring system to ensure the power supply beyond its borders.
Retrofit: Bushing monitoring for phase shifters
Bushings are one of the most important parts of the transformer. That is why Slovenian grid operator ELES relies on the MSENSE® BM monitoring system to ensure the power supply beyond its borders.
To prevent this from happening, ELES switches off its PSTs in Divača every year in August for exactly two weeks to conduct thorough maintenance. In 2020, the grid operator used this time window for a retrofit. The previous monitoring system on two PSTs was replaced by the new MSENSE® BM bushing monitoring system from MR. As Polajner tells us, "Bushings are some of the most important parts of the transformer. Fault-free operation of these transformers depends greatly on the varying weather conditions, which means that continuous status monitoring is essential. Because the existing system had to be replaced, we began looking for a new solution, and we chose the MSENSE® BM from MR."
A simple explanation of high-voltage bushing monitoring.
Installing the sensors for bushing monitoring is simple
Workers from a local service company performed the retrofit. With the aid of simple instructions, they attached the sensors of the MSENSE® BM to each of the twelve OIP (oil impregnated paper) bushings of all phase shifter transformers completely independently. Then, an MR commissioning specialist showed the team how to individually adjust the parameters that were already stored in the system as needed – and that was all it took for the electricity to flow between Slovenia and Italy more reliably than ever.
Successful retrofit on the phase shifter
In addition to transferring electricity to Italy, ELES also operates transmission grids that are connected with Austria and Croatia. They are currently planning a connection to Bulgaria. This makes ELES part of the Europe-wide Multi-Regional Coupling (MRC) project. As Polajner explains, "Our partners count on the reliability of our systems. That is why we are so careful when it comes to choosing the companies we work with. Our current transformers are already equipped with MR system solutions. Our experience in recent years has demonstrated that MR offers excellent support as well as innovative, reliable, safe solutions. By deciding to implement the MSENSE® BM monitoring system going forward, we are already benefiting today from service from a single source."
How MSENSE® BM online monitoring works
MR designed the MSENSE® BM online monitoring system for reliable monitoring of high-voltage bushings. An innovative algorithm monitors their capacitance as well as the dissipation factor, and compares any deviations with predetermined limit values. The system immediately notifies higher-level systems if the limit values are exceeded, before the transformer sustains any damage. MSENSE® BM features an innovative concept that uses double reference methods that monitor the condition of the bushing insulation based on a change in capacitance and the dissipation factor in a three-phase system.
