A particular AC component protection scheme for bipolar HVDC transmission lines

Abstract

The line protection methods for high-voltage direct current (HVDC) transmission system in engineering applications are poor in sensitivity and reliability. In this paper, we introduce a new notion of energy, namely a particular AC energy, based on which a particular AC component protection scheme is proposed. The scheme is comprised of start-up criterion, fault identification criterion, and faulty pole identification criterion. The start-up criterion is based on the fact that particular AC component measured at both terminals increases rapidly when a fault occurs. The particular AC energy calculated by particular AC component at both terminals behaves differently in the face of an internal or external fault, and this characteristic is applied to construct the fault identification criterion. The particular AC energy on the non-fault line is smaller than that on the faulty line, which can be used to establish the faulty pole identification criterion. Compared with other energy-based protections, the proposed method does not require data synchronization and is not affected by the distributed capacitive current of the transmission line. Comprehensive simulation experiments including real-time digital simulator (RTDS) tests indicate that this method is able to operate reliably under various fault conditions with satisfactory accuracy and high sensitivity.

Calculated DC resistance‐based pilot protection scheme for bipolar high‐voltage direct current transmission lines

“…If both relays identify the fault coming from forward, it is an internal fault. The fault direction can be determined by using (14). Thus, the fault discrimination criterion can be expressed as…”

“…Theoretically, the unit protection is able to protect the whole DC line. In [14, 15], pilot protections based on transient energy ratio of line boundary are proposed to detect high fault resistances. However, the voltage and current data at the measuring points (a, b, m and n) at the valve and line sides at both line ends are required to apply both schemes [16].…”

“…Another method to achieve fault detection is utilizing the voltage of smoothing reactor of the line boundary [17]. However, the effect of the distributed parameter characteristics of transmission lines and distributed capacitive current is not considered in these two‐ended boundary protections [14, 15, 17]. By removing the effect of the distributed capacitive current, an improved differential protection scheme is proposed in [18].…”

A novel intelligent fault identification method based on random forests for HVDC transmission lines

“…After analyzing the amplitudefrequency characteristics of the physical boundary consisted by smoothing reactor and DC filter on both sides of the HVDC transmission line, it is found that high-frequency signals are blocked by physical boundaries [2], which provides ideas to establish criteria by using high frequency energy. According to the attenuation characteristic of HVDC transmission line boundary elements to high frequency transient signals, references [3,4,5] respectively use wavelet energy, polar wave information entropy, and high frequency transient energy to quantitatively describe, analyze and estimate fault characteristics, so as to realize the identification of internal and external faults. These methods can effectively identify internal and external faults, but the threshold setting has no theoretical basis and requires numerous simulation verification.…”