Time domain model identification pilot protection method suitable for wind power system

Abstract

The invention discloses a time domain model identification pilot protection method suitable for a wind power system. The method comprises the following steps: collecting three-phase voltage and current at the protection installation place and forming differential voltage and differential current; judging whether to start time domain model identification pilot protection according to the differential current value; calculating each phase of differential current and correlation coefficient rho of a first-order derivative of the differential voltage obtained after zero sequence compensation; judging internal and external faults by comparing the value of each correlation coefficient rho with a set threshold value; if the correlation coefficient rho of any phase is smaller than the set threshold value, judging that the fault is the internal fault, and then, pilot protection at the two ends of a line is carried out to protect the device to act reliably; or otherwise, judging that the fault is the external fault so as protect the device not to act reliably. The time domain model identification pilot protection method is easy to realize, can carry out split-phase judgment, is fast in action speed, is not influenced by line distributed capacitive current and fault resistance, and can be widely applied to the wind power system.

Description

technical field [0001] The invention relates to the field of new energy grid-connected relay protection, in particular to a time-domain model identification longitudinal protection method suitable for wind power systems. Background technique [0002] With the increasingly serious energy crisis and environmental pollution, the development and utilization of green energy has been paid more and more attention. Large-scale development of various renewable energy represented by wind energy and solar energy has become an inevitable choice for human society to achieve long-term sustainable development. . However, with the large-capacity random fluctuating new energy power connected to the grid, it will definitely have a greater impact on the power system, and at the same time bring a series of technical problems to the operation of the system. [0003] At present, there is a lack of operation experience of large-scale random energy access to the transmission and distribution netwo...

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Problems solved by technology

[0005] Fault characteristics such as weak feed, high harmonics, frequency offset, and system impedance instability of the wind power system have caused the unsuitability of traditional relay protection, resulting in the requirements for relay protection of wind power systems that are different from conventional system fault characteristics. In addition, The model of faults inside and outside the zone is different from the traditional relay protection. Therefore, a longitudinal protection method that can be applied to wind power systems is needed

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