The Research Of Relationship Between New Hybrid-type HTSCFCL And Distance Protection Of Power Grid

The fast deve lopme nt of power system leads to sharp increase of s hort circuitbreaking capacity and fault c urrents, the ava ilable fault current le ve l may increasebeyond the capabilities of the existing equip ment, leaving circ uit breakers and othersubstation compone nts in a ll over-duty cond ition. Electrical equip ments are subject toshort-circuit capacity, which makes switching equipme nt cost increased dramatica lly,not even se lectio n. To limit the cost of s hort-circuit current through thetransformation of the electric ity network structure is extre me ly expens ive, changingthe syste m operating mode and paralle l with conventiona l current limiting reactor tolimit short-circuit will cause the instability of power system. Under this circums ta nces,the power syste m short-circuit curre nt limiting device came into being and has beendeve loping. The most ideal o ne of s uch devices is the s uperconducting fault c urrentlimiting device. In a normal work conditio n, it is a good conductor with no influenceon power system, however, in the case of short-circ uiting, its impedance abruptlyincrease to limit short current and circuit breaking capac ity. It works natura lly and isself-exa minatio n, self-triggered, self-operation a nd self-restore. Due to limit ingimpedance in series, the most direct impact to the grid is on rela y protectio n.By means of the fast and real-time features of computer protection, this paperwill mod ify the tuning algorithm for the dista nce protection, and then solve theproble m between hybrid type superconducting current limiter and d istance protection.The main tasks are:(1).Through the study of hybrid high-temperature superconducting currentlimiter, establish a mathe matica l model o f suc h current limiter for110kv vo ltageleve ls, the n use the MATLAB s imulation to verify its limiting effect;(2).Ana lys is the influence of hybrid high-temperature superconducting currentlimiter to the selectivity a nd sens itivity o f d istance protectio n from the actionequation and characteristics of impedance round, and the n, verified by simulation;(3).Improve the a lgorithm o f rela y protection, and adjust the rela y setting toeliminate the influence of superconductor limiter on the sens itivity and selectivity ofdistance rela y eventua lly. Focus on the influence of new hybrid high-temperaturesuperconductor current limiter on d istance protection, and the upgrade of distanceprotection performance after improving the algorithm, and us ing MATLAB prepared simulation program.All works above not only in terms of theory de monstrate the feasib ilities andadvanta ges of the new algorithm to eliminate the influe nce of hybrid SCFCL to thedistance protectio n, but also make fundamenta l effort for fo llowing exp loration of theproducts based on SCFCL.