Transactions of China Electrotechnical Society  2025, Vol. 40 Issue (4): 1287-1306    DOI: 10.19595/j.cnki.1000-6753.tces.240156
Current Issue| Next Issue| Archive| Adv Search |
Power Differential Protection for Active Distribution Networks Considering Voltage Drop Differences
Luo Guomin1, Tan Yingjie1, Wu Mengyu1, He Jinghan1, Tang Pingzhou2
1. School of Electrical Engineering Beijing Jiaotong University Beijing 100044 China;
2. Guangxi Power Grid Co. Ltd Nanning 530000 China

Download: PDF (2424 KB)   HTML (1 KB) 
Export: BibTeX | EndNote (RIS)      
Abstract  With the integration of a large number of inverter-interfaced distributed generators, the system structure, power flow direction, and operation mode of the distribution network have changed, and traditional single-end protection is rugged to meet the requirements. Differential protection has advantages in new distribution networks due to its excellent selectivity and sensitivity. However, for medium voltage distribution networks, because distributed power sources and loads are mainly connected through T-connected, the unobservability damages the original fault characteristics, making it difficult to balance selectivity and sensitivity in protection. This paper proposes a power differential protection method for distribution networks with T-connected IIDGs and loads.
Firstly, considering the output characteristics of inverter-interfaced distributed generators during low voltage ride through, an amplitude comparison criterion using fault component positive sequence is proposed. When a near-end fault without grounding resistance occurs, the voltage drop of the line is high, and the fault component characteristics are significant. By mining the amplitude and directional characteristics of the positive sequence differential power of the fault components at both ends of the distribution line, a protection strategy is constructed to adapt to high-voltage drop faults. Besides, the dead-zone problem of power differential protection is solved.
Secondly, regarding the insignificant fault component characteristics, a power differential criterion is constructed by approximately calculating the power of each T-connected IIDG or load through the electrical quantities at both ends to improve protection sensitivity. The protection ranges of these two criteria are estimated, and protection setting coordination is proposed. This protection can identify faults inside and outside the zone, effectively improving the adaptability of differential protection in distribution networks with T-connected IIDGs and loads.
Finally, a simplified simulation model of a 10 kV distribution network is constructed. The following conclusions are drawn. (1) The protection criteria based on the active power characteristics of fault components can overcome the influence of T-connected IIDGs and loads. High voltage drop faults can be accurately identified in the inside and outside zones. (2) In the proposed protection method, a real-time estimation algorithm is used for the fault power contribution of IIDGs and loads, enabling the protection method to withstand a 300 Ω transition resistance. (3) The proposed method is a differential protection using measurement data from both terminals. Additional measurement devices are not required for T-connected IIDGs and loads. Compared with over-current protection, the proposed method has a significant advantage in operating time. (4) The proposed protection method is not affected by fault types and locations, IIDG penetration rate, capacity of T-connected and loads, noise, and grounding methods, showing strong adaptability. The effectiveness of the proposed protection method is verified. It can serve as a powerful supplement to protect the current distribution network, thereby improving the reliability and sensitivity of protection.
Key wordsActive distribution grids      integration of distributed generator      voltage dips      unmeasurable branches     
Received: 22 January 2024     
PACS: TM773  
Service
E-mail this article
Add to my bookshelf
Add to citation manager
E-mail Alert
RSS
Articles by authors
Luo Guomin
Tan Yingjie
Wu Mengyu
He Jinghan
Tang Pingzhou
Cite this article:   
Luo Guomin,Tan Yingjie,Wu Mengyu等. Power Differential Protection for Active Distribution Networks Considering Voltage Drop Differences[J]. Transactions of China Electrotechnical Society, 2025, 40(4): 1287-1306.
URL:  
https://dgjsxb.ces-transaction.com/EN/10.19595/j.cnki.1000-6753.tces.240156     OR     https://dgjsxb.ces-transaction.com/EN/Y2025/V40/I4/1287
Copyright © Transactions of China Electrotechnical Society
Supported by: Beijing Magtech