• AKSHAYKUMAR N. WANKHADE
• prof. Roshan R. Deotare

Multi-terminal flexible HVDC grids are required due to the high penetration of renewable energy. However, protection issue remains a major challenge. This is largely due to the low inductance in DC network compared to AC interconnection which usually results in a sudden collapse in the DC voltage and rapid rise in the fault current thus reaching damaging levels in few milliseconds. Therefore, faults in MT-HVDC system must be detected and cleared quickly before it reaches a damaging level; typically, 4 – 6ms (including circuit breaker opening time) following the inception of the fault. For this reason, transient based protection techniques are ideal. The protection scheme must be reliable and dependable. Transient based protection algorithms utilize the higher frequency components of the fault generated signal to detect a fault, therefore making it possible to detect the fault while the fault current is still rising and well before the steady state. The traditional protection algorithms developed for conventional high voltage AC (HVAC) systems such as distance protection are steady state based and as such not suitable for the protection of MT-HVDC systems. Non-unit line protection devices which will operate at a sufficient speed and which will isolate only the faulty section in the event of a fault are therefore required to avoid a total system failure during short circuit. They are vulnerable to dc faults. To ensure their high reliability and continuous operation, fast and selective protection schemes are indispensable. This project analyses the transient voltages in the case of dc line faults in modular multilevel converter (MMC)-based HVDC grid. A MMC-based four terminal HVDC grid is modeled using MATLAB, and extensive simulations are conducted to validate the effectiveness of the proposed scheme.

DC line protection; Multi-terminal HVDC grid; Fault classification; Faulty pole selection; Fault transient voltage.

"PROTECTION SCHEME FOR UNIPOLAR MMC-BASED MULTI-TERMINAL HVDC GRID", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.8, Issue 7, page no.e626-e631, July-2021, Available :http://www.jetir.org/papers/JETIR2107585.pdf

"PROTECTION SCHEME FOR UNIPOLAR MMC-BASED MULTI-TERMINAL HVDC GRID", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.8, Issue 7, page no. ppe626-e631, July-2021, Available at : http://www.jetir.org/papers/JETIR2107585.pdf