小電流接地系統發生單相接地故障時，穩態電流微弱，暫態電流比穩態電 流大數十倍。為了更準確地對小電流接地系統進行故障選線，首先提出了暫態 信號相對強度 (Q) 的概念，並通過模擬實驗，確定了Q 的選線參考值Q0。然 後將希爾伯特–黃變換 (HHT) 方法與穩態零序電流選線法相結合，提出一種 綜合暫態量和穩態量的選線方法，依據暫態信號相對強度Q 的大小，當Q < Q0 時，採用HHT 奇異性檢測法進行故障選線；當Q  Q0 時，採用穩態零序電流 法進行故障選線。該方法充分利用暫態和穩態資訊，彌補了以往單一選線法的 不足。模擬結果表明，所提出的基於暫態信號相對強度的小電流接地系統綜合 選線法方法不受故障相角及接地電阻的影響，具有較高的準確性和可行性。

In order to obtain more accurate results of fault line detection in non-solidly earthed systems, this paper puts forward the concept of fault transient signal relative intensity (Q), and provides a reference values Q0 of Q by simulation test for fault line detection. Based on this, a new method of combining Hilbert-Huang transform (HHT) with the steady-state zero sequence current method is proposed. According the value of Q, when Q < Q0, the HHT was used for fault line detection, and the Q  Q0, steady-state zero sequence current method was used instead. The proposed method makes full use of transient and steady-state line information, and overcomes the shortage of the previous method only using single criterion to detect fault line. Simulation results showed that this method is not affected by the fault initial phase angle and grounding resistance, and also has high accuracy and feasibility