Research On Line Length Compensation Line Compensation Strategy Based On Measured Data

High-voltage transmission line power system as the aorta,reliable and efficient operation of the entire system is related to security and stability,but the harsh operating environment makes high-voltage transmission line failure rate rank first in the power system.When fault occur in transmission line,a fast and accurate fault locating method,can not only reduce the uncertainty of transmission line patrol,shorten the time of restoration,but also reduce the economic losses due to power outage,therefore,the accuracy of fault location is particularly important.For modern traveling wave fault location,the actual velocity decay is replaced by the the constant velocity which causes the velocity error,the real-time line length in variable operating conditions is replaced by designed line length which causes line error.To reduce the impact of these two factors,it is necessary to introduce a line length calculating method based on real-time operating state and the empirical velocity.This paper proposes a line length calculating method based on traveling wave which combines the empirical velocity and the time when the first peak of the traveling wave is measured.This method is adaptive to various factors(such as weather conditions,route structure,experience velocity).Calculating line length based on the traveling wave instead of the designed line length can reduce the impact of various factors on the fault locating accuracy.This paper takes the measured data of traveling wave fault loacation thesis as the background,using the principle of fault location to calculate line length then make comparition to the engineering designed line length,analyses the main factors affecting the result traveling wave fault location.The mian factor affecting the accuracy of result is height and empirical velocity,especially in the undulating mountains,the calculating error of line length caused by height is about 2%,the calcution error of line length owing to the empirical velocity of traveling wave velocity depends on the location of fault,the more distance between fault location and measurement end and the bigger error occurs.For the same fault,the calculation result of line length based on traveling wave is different between two measurement ends,otherwise,when the line length calculating by traveling wave from serial fault in the same location,the result is approximative.Combining the analysis with the impact of measured data,this paper proposes a traveling wave calculation strategy based on historical cases to reduce the calculation error of line length.This strategy first takes historical data cases into consideration,and then applies the theory calculating method.To improve the accuracy of historical cases library,the searching-reusing-revising-learning action needs to be processed repeatively.This paper gives two examples to demonstrate the effectiveness of the strategy,one example is calculated by the historical cases,another is calculated without historical cases,and the results show the strategy can improve accuracy of fault location accuracy in certain degrees.This strategy can not only compensate for the calculation of line length in traveling wave under different operating conditions and improve the accuracy of fault location and positioning,but also reflect the location and cause of the frequent occurrence on tramission line.