Optimisation of MSR & MSC switching instances during Auto mode operation of STATCOM to enhance the life of the equipment

(MSR) and Capacitors (MSC). However, frequent switching of MSR/MSCs during

STATCOM operations raises significant concerns about the longevity and reliability of the associated equipment, particularly circuit breakers.

The challenge arises predominantly in grids with higher SCL, where even minor fluctuations in bus voltage can trigger excessive reactive power adjustments, and where the voltage band may remain unchanged for extended periods even though the grid SCL changes. This results in continuous MSR/MSC switching, which can accelerate wear and tear, leading to malfunctions and failures over time. Observations from multiple STATCOM installations across India indicate that frequent MSR/MSC switching is prevalent, especially during seasonal load changes and generation shutdowns, exacerbating the life-cycle issues of essential grid components, such as circuit breakers.

In response to this pressing concern, this paper presents an optimisation logic to reduce the frequency of MSR/MSC switching. The proposed solution involves establishing adaptive voltage bands based on the current SCL of the grid and historical voltage data from the previous year. By implementing this logic, operators can input the defined voltage limits into the STATCOM controller, thus minimising unnecessary switching events. The effectiveness of this optimisation logic was evaluated through a case study that analysed historical data alongside actual switching records during the specified period. The comparison revealed a clear potential for reducing the number of MSR/MSC switching events had the proposed logic been applied. The analysis also included results from annual maintenance tests of circuit breakers, Digital Fault Recorder (DFR) analysis, and inspections. These results highlighted deterioration of arcing contacts and provided evidence of the negative impact of frequent switching on equipment reliability.

In conclusion, the optimisation logic helps reduce the adverse effects of frequent MSR/MSC switching while improving overall power system performance. By extending the lifespan of key components such as circuit breakers, this approach supports the sustainability goals of modern electrical grids. This study lays the groundwork for future research to enhance the reliability of STATCOM systems across diverse SCL environments.