Method and system for setting voltage change rate criterion of direct current line travelling wave protection

Abstract

The invention relates to a method and a system for setting a voltage change rate criterion of direct current line travelling wave protection. The method comprises the following steps: carrying out smoothing reactor valve side metalline earth fault simulation in a simulation model of a direct current transmission system, and obtaining a plurality of first current differential voltage values by sampling direct current bus voltage at each interval of scheduled time, so as to obtain an external fault protection characteristic quantity change boundary; carrying out terminal metalline earth fault simulation in the simulation model, and obtaining a plurality of second current differential voltage values by sampling the direct current bus voltage at each interval of scheduled time, so as to obtain an internal fault protection characteristic quantity change boundary; determining a protection setting value according to the external fault protection characteristic quantity change boundary and the internal fault protection characteristic quantity change boundary. By the method, the change boundaries of the protection characteristic quantity in the internal fault and the external fault can be accurately determined, so that the protection setting value can be accurately determined and quantitative evaluation on the protection performance is achieved.

Description

technical field [0001] The invention relates to the field of direct current transmission systems, in particular to a method and system for setting the voltage change rate criterion for traveling wave protection of direct current lines. Background technique [0002] Traveling wave protection is the main protection technology for DC lines commonly used in DC transmission systems, and it plays a vital role in ensuring the safe and efficient operation of DC transmission systems. The typical operating criteria of DC line traveling wave protection are shown in formulas (1) to (3): [0003] du / dt>du / dt set (1) [0004] Δu>Δu set (2) [0005] Δi>Δi set (3) [0006] Among them, formula (1) is the criterion of voltage change rate, du / dt represents the voltage change rate, du / dt set is the action value of the criterion; formula (2) is the criterion of voltage change, Δu represents the voltage change, Δu set is the action value of the criterion; formula (3) is the crite...

AI Technical Summary

Problems solved by technology

[0011] Fault traveling waves contain a wealth of transient information. At present, the sampling interval of traveling wave protection devices is generally 100 μs or 150 μs. Due to the randomness of the sampling of protection devices, the actual sampling data must have fault information loss compared with the original data. Therefore, it is impossible to determine the change boundary of the protection characteristic quantity when there is an internal fault and an external fault.

It is precisely because the change boundary of the protection characteristic quantity cannot be determined, the current criterion setting of the voltage change rate of the traveling wave protection can only rely on the method of trial and error.

The method of trial and error is difficult to exhaust all possibilities. Once an unexpected situation occurs in actual operation, it is very likely to cause incorrect action of the DC line traveling wave protection

[0012] Therefore, the accuracy of the existing method for determining the voltage change rate criterion of traveling wave protection for DC transmission lines is not high

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