An Adaptive Overload Protection Method for Transmission Lines Considering Dynamic Thermal Characteristics

Abstract

The invention discloses a transmission line self-adaptive overload protection method considering the dynamic thermal characteristics. When the line current amplitude is greater than the maximum allowable current of the line, the protection is started, and the line power is measured every Δt time; the sampling power is compared with the line power The size of the allowable long-term operating power, if the sampling power is greater than the allowable long-term operating power of the line, calculate the estimated allowable overload time of this sampling; then compare the estimated allowable overload time of this sampling with the size of the next sampling time, If the estimated allowable overload time of this sampling is less than or equal to the next sampling time, the protection action time is set, and when the overload duration meets the protection action time, the overload line is cut off. The invention can delay taking protection measures for overloaded lines as much as possible under the condition of line safety, taking into account line safety and chain failure risks, and does not depend on communication, simple in principle, easy to implement, and has high reliability and sensitivity .

Description

technical field [0001] The invention relates to the field of power system relay protection, in particular to an adaptive overload protection method for a transmission line that takes dynamic thermal characteristics into consideration. Background technique [0002] Transmission line currents exceeding the allowable long-term operating current will cause line overloading. In a modern power system, affected by factors such as equipment aging, bad weather, and heavy-load operation, the power flow transfer caused by the outage of a single-fault component can easily lead to an overloaded state of the line in normal operation. At present, transmission lines are generally equipped with overload protection as backup protection in case of line failure. However, when the line is overloaded, the current is greater than the overload protection setting value, causing the protection action to cut off the line, resulting in further flow transfer, often triggering a wider range of cascading...

AI Technical Summary

Problems solved by technology

However, the prior art adopts a constant overload power

During the line overload period, the adjustment of the power grid topology and power output will cause the power distribution and size of the grid to change continuously, which will change the temperature rise speed of the overloaded line. The allowable overload time calculated by using constant power also has a large error, which may lead to Cascading faults caused by too fast removal of the line, or possible damage to the line due to delayed removal

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