Protection Study Of Magnetic Valve Controllable Reactors

With the construction of ultra high-voltage power grid,controllable reactor becomes the very important reactive power compensation device.Therefore,it is extremely essential to configure protection for controllable reactor.This thesis focus on the protection study of 500kV magnetic valve controllable reactors:Firstly,the model dealing with inter-turn fault of primary winding is established on PSCAD. Then the main and backup protection schemes are fixed by analyzing the faults of the magnetic valve controllable reactors and simulation.Based on the characteristic of the magnetic valve controllable reactors,which is adjusted continuously,the protection principle of floating threshold based on normal working current under different capacities is introduced in order to improve the sensitivity of protection. Aiming at inter-turn short circuit fault of primary winding,the thesis proposes over-current protection based on the thrice harmonic of current and analyses its work principle.Adding a group of current transformer nearby the ground point of secondary winding,the protection sensitivity of earth fault could be improved by the fault current passing the ground point.The DC over-current protection based on DC component of the fault current is introduced for the earth fault on the line with the rectifiers.Finally,the protection domain and sensitivity of each protection proved to meet the requirement of the standard.