To raise power supply dependability, promotion uses cable, cancel lead of built on stilts stage by stage, my bureau uses power supply of switch station mode in the city zone and developing zone. Current, already investment of 7 switch station moves, plan a the city zone (make an appointment with 10km2) to delimit 10, every build a switch to stand together, the city zone will use switch station power supply entirely henceforth. The switch station of the city zone realized letter of remote control, Yao, telemetering, every switch station has source of 2 wire back to take a line (at present of short duration is bout) , station of every 3 switch is for a group of intercommunicate, each other reserve, with raising the power supply dependability that switch stands further. From 1992 investment of station of the 1st switch moves to now, these switch stations developed their function adequately, satisfied the demand that we expect.
But these switch stations also appeared in move a few problems, list below 2 among them main problems, try to analyse, put forward to improve measure, raised the power supply dependability that switch stands further.
Tripping operation of 1 switch bypass the immediate leadership
(1) accident phenomenon
When switch station gives line line to malfunction, meeting occurrence switch stands not tripping operation, and change the appearance of tripping operation of bypass the immediate leadership that electric place gives line switch tripping operation. , the high-pressured side of subscribers transformer produces alternate with short circuit, change except the user outside side switch tripping operation, switch station side gives line switch and switch station to enter line switch also tripping operation of bypass the immediate leadership, cause power failure of switch station complete station, in the meantime, switch stands " 3 Yao " the function is interrupted, enlarged power cut limits, extended power cut time.
(2) case study
Before 1997, my bureau changes the protective time limit that electric place 10kV gives a clue is fast break 0.5s, shed 1s too. Go up to have time limit cooperate, design program uses: Ark of line of switch station pass in and out all is go protection of billabong type specified time, time limit is whole it is surely fast break 0.1s, shed 0.4s too, the user deserves high to use go billabong type turns over time limit protection. But, the construction as electrified wire netting and transform, the short circuit size of circuit is larger and larger, like me the 110kV Jing De of the bureau changes, should change electric place is proximate the power plant that press down the sea, the short circuit capacity of its 10kV generatrix is in 371MVA of make known to lower levels of the biggest run mode, so large short circuit size short-circuits in circuit when, reach to knife of brake of cable, circuitry change the concussion of electric place facility and attaint are very big, my bureau already happened many times to be caused because of circuit short circuit change the accident of attaint of platoon of electric place mother and burn down of circuit brake knife. For this, it is at the beginning of 1997, overall situation changes the protective time limit that electric place 10kV gives a clue is adjusted for fast break 0.1s, shed 0.4s too, in the meantime, change the time relay of electric place also by electromagnetism model change relay of time of high accuracy static state. Because the time limit of switch station makes calm cost already small arrive cannot again little room for action, accordingly, switch station and change the abundant that cooperates to go up without time limit between electric place is spent, accident of tripping operation of bypass the immediate leadership has repeatedly happen. Because switch station is used,go billabong means tripping operation, once change,electric place stands at switch first tripping operation, cut off fault current, criterion because lose,switch station switch is met divide brake electric current and cannot tripping operation; Right now, change electric place gives line switch to be when coincide brake, go up in fault line with respect to assemble, cause coincide brake failure. Additional, the user in devising plan matchs high, oneself time limit cooperates to be not worth between switch of line of switch station pass in and out, when causing an user to deserve high to malfunction, switch of line of switch station pass in and out and user match switch of line of pass in and out high brake of one take off. Because switch stands " 3 Yao " power source is taken press oneself change reach public change, switch stands into the line or change electric place gives a clue one tripping operation, "3 Yao " power source disappears, "3 Yao " the function is interrupted subsequently.
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