A new pilot directional protection method for HVDC line based on the polarity of inductive energy

Abstract

Concerning the poor immunity of DC line protection to fault resistance in the case of internal fault and its mal-operation proneness in the case of external fault, a new pilot directional protection scheme for HVDC line in AC/DC hybrid system based on the polarity of inductive energy is proposed. First, by analysing the conducting state of converter at different time sections, the impedance characteristic equations of converter in different commutation failure scenes are derived. On this basis, by combining the impedance characteristics of other components in DC system, the fault component network of an AC/DC hybrid system consisting of inductive impedances is established. Then, according to the difference in the flowing direction of the inductive energy in the fault component networks of internal and external faults, a protection criterion for identifying internal and external faults is constructed. Finally, simulation tests in RT-LAB verify that, the proposed method can accurately identify internal and external faults in different fault cases, unaffected by commutation failure and lightning interference and highly immune to the fault resistance. Besides, the proposed method does not involve real-time interaction of synchronous information, thus it is simple and reliable.

Non‐unit protection scheme for HVDC transmission lines based on energy of voltage difference

“…The proposed protection scheme has a higher operation speed than [6, 15, 17–19, 21, 22, 24, 28, 30–32] and has the same operation speed as other schemes. One of the benefits of travelling‐wave protection schemes is their high operation speed.…”

“…Compared to the schemes [10–12, 19–22, 26–33], which require the exchange of information between both sides of the transmission line, the proposed protection scheme is a single‐end protection and uses only local voltage measurement at the rectifier side. Therefore, all the measuring and protective devices are installed at the rectifier side and there is no communication link between the two sides of the system.…”

“…The schemes of [7–12, 23–28, 30–33] use both voltage and current signals, therefore they require more measurement equipment and cost. The proposed protection scheme uses only single‐end voltage data.…”

“…Proposed protection scheme have higher sampling frequency than [7, 8, 12, 14–17, 19–24, 29, 30, 32], have identical sampling frequency with [18, 27, 28, 31, 33], and has a lower sampling frequency than [6, 9–11, 13, 26].…”

“…In [29], a pilot protection scheme based on Pearson correlation coefficient (PCC) of current derivatives is proposed. In [30, 31], two pilot protection methods based on the polarity of inductive energy and measured surge impedance at tuning frequency are presented, respectively. A pilot directional protection scheme based on voltage difference between positive and negative poles (VDPN) is proposed in [32].…”