Power transmission line adaptive overload protection method considering dynamic thermal characteristics

Abstract

The invention discloses a power transmission line adaptive overload protection method considering dynamic thermal characteristics. The method comprises the steps of starting protection when the current amplitude of a line is greater than the maximum allowable current of the line, and measuring the power of the line every delta t; comparing the sampling power with the allowable long-term operation power of the line, and if the sampling power is greater than the allowable long-term operation power of the line, calculating the estimated allowable overload time of the current sampling; and then comparing the estimated allowable overload time of the current sampling with the next sampling time, if the estimated allowable overload time of the current sampling is less than or equal to the next sampling time, setting the protection action time, and when the overload duration meets the protection action time, cutting off the overload line. According to the method, protection measures can be delayed as much as possible on the overload line under the condition of line safety, line safety and cascading failure risks are taken into consideration. The method is independent of communication, simple in principle, easy to implement and high in reliability and sensitivity.

Description

technical field [0001] The invention relates to the field of relay protection of power systems, in particular to an adaptive overload protection method for transmission lines considering dynamic thermal characteristics. Background technique [0002] If the current of the transmission line exceeds the allowable long-term operating current, the line will be overloaded. In modern power systems, affected by factors such as equipment aging, severe weather, and heavy load operation, the power flow transfer caused by the outage of a single faulty component can easily lead to the evolution of a normally operating line into an overload state. 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 shifting of the power flow, often triggering...

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

Images