Pilot protection method based on Spearman rank correlation coefficient

Abstract

The invention discloses a pilot protection method based on Spearman rank correlation coefficient. The method comprises the following steps: firstly acquiring fault features of different types of supply transient current according to transient short-circuit current expressions of different types of power supply; measuring waveform difference of transient current at two sides when an internal of thenew energy terminal outgoing line occurs by utilizing the Spearman rank correlation coefficient; and distinguishing the internal and external faults according to the waveform difference of transientcurrent at two sides when the internal fault occurs, thereby realizing the pilot protection on the new energy terminal outgoing line. By utilizing the method disclosed by the invention, the internal and external faults can be reliably distinguished, and the reliable pilot protection on the new energy terminal outgoing line is realized.

Description

technical field [0001] The invention relates to the technical field of power systems, in particular to a longitudinal protection method based on Spearman rank correlation coefficient. Background technique [0002] Large-scale new energy access has become an inevitable trend in the field of energy and power in my country. However, the fault characteristics of new energy power supply are affected by the low voltage ride-through control strategy, showing sequence impedance instability, phase angle control, frequency offset, high-order Harmonics and other characteristics, which make the traditional ratio brake differential protection a huge challenge, so the study of reliable new principles of longitudinal protection is of great significance for the efficient use of new energy. [0003] In the prior art, there are few research results on the longitudinal protection of outgoing lines, and the main methods focus on the two aspects of frequency domain and time domain. In the freque...

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Problems solved by technology

In the frequency domain, the difference in the ratio of the differential voltage of the fault component to the differential current of the fault component can be used to distinguish the internal and external faults, but the method based on the power frequency is affected by the current frequency offset of the doubly-fed fan. In the time domain, one is to use whether the first-order derivative of the differential voltage and differential current conforms to the capacitance model to distinguish internal and external faults, but the first-order derivative is affected by high-frequency components, and the protection performance is slightly poor

The other is to measure the difference between the transient current waveforms on both sides through the Pearson correlation coefficient. However, this method cannot operate correctly under the condition of weak output of new energy sources and overlaps with permanent faults. Therefore, it is necessary to study new longitudinal protection. method

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