Е-Публикации
Технически университет - София

Abstract: In recent years, a significant increase in the integration of photovoltaic power plants into electrical power systems has been observed. Projects with installed capacities exceeding 100 MW are becoming increasingly common. Such large-scale PV plants typically incorporate a substantial number of LV/MV transformers. The simultaneous energization of the entire plant can generate a considerable inrush current at the point of connection to the substation. This situation increases the risk of non-selective operation of protection relays. The present paper aims to investigate second harmonic blocking algorithms implemented by leading manufacturers of relay protections.

References

1. I. Popov, “Electrical Machines. Vol. II: Transformers”, 3rd ed., Sofia, Bulgaria: Technika, 1960
2. G. Ziegler, “Numerical Differential Protection: Principles and Applications”, 2nd ed., Erlangen, Germany: Publicis Publishing, 2012
3. N. Vitkov, “Energy Policy and Challenges to The Sustainable Development of PV Generation in Bulgaria and Environmental Consequences”, 2023 15th Electrical Engineering Faculty Conferene (BulEF), Varna, Bulgaria, 16-19 September 2023, DOI:10.1109/BulEF59783.2023.10406287
4. N. Avramov, “Fundamentals of Relay Protection”, Sofia, Bulgaria: Technika, 1984
5. “SIPROTEC 5 Transformer Differential Protection 7UT82, 7UT85, 7UT86, 7UT87. Manual”, version V9.80, Siemens, June 2024
6. “Easergy P3F30 Feeder Protection Relay. User Manual”, Scneider Electric, November 2022
7. “PowerLogic P7 Protection and Control Device. User Manual”, Scneider Electric, September 2024
8. “REX615. Technical Manual”, revision B, ABB, August 2024
9. “Transformer Protection RET670. Technical Manual”, version 2.2 IEC, Hitachi Energy, March 2025

Issue