A Novel Multi-Modular Series HVDC Tap

Abstract

Tapping energy from a HVDC transmission line to serve small remote communities has been considered by researchers and HVDC manufacturers since the 1960s. Many HVDC taps proposed consider the performance of diodes, Thyristors and GTOs and the utilization of bulky and expensive high voltage transformers. This paper proposes a novel HVDC tap topology, the n-phase multi-modular series tap (MMST), which utilises capacitors to decouple HV voltage and IGBT H-bridge sub-modules typically found in modular multilevel converters to transfer HVDC to MVAC. The number of phases and operating frequency can be picked according to the requirement of the application. The feasibility of n-phase MMST has been verified by the results from simulation carried out in PLECS software.

Input‐voltage and output‐current equalization of series‐in parallel‐out three‐phase multi‐module voltage source converter‐based high voltage direct current shunt tap

“…The small tapping station should satisfy some conditions such as low cost, negligible impact of the main DC‐link and no clashes between tap and DC‐link controllers 4 . As mentioned before, there are two possible options to tap small amount of power from the power transferred through the HVDC line, namely, parallel‐tap 5–10 and series‐tap 11,12 . The shunt tap valves are rated at the full high DC voltage, which necessitates employment of series‐connected IGBTs to implement the high‐voltage valve; which makes the shunt tap has higher cost compared to the series tap.…”

“…4 As mentioned before, there are two possible options to tap small amount of power from the power transferred through the HVDC line, namely, parallel-tap [5][6][7][8][9][10] and series-tap. 11,12 The shunt tap valves are rated at the full high DC voltage, which necessitates employment of series-connected IGBTs to implement the high-voltage valve; which makes the shunt tap has higher cost compared to the series tap. However, the problem of the series connection makes the shunt tap more reliable.…”