Loop security automatic controlling system capable of resisting 30-degree angle error

Abstract

The invention discloses a loop security automatic controlling system capable of resisting a 30-degree angle error, wherein an auxiliary contact QF2-1and a switching sheet XB1 of a standby power supply switch are connected in parallel, and then are connected with a switching control loop and a switching coil LC1 of a main power supply in serial; an auxiliary contact QF-1 and a switching sheet XB2 of a main power supply switch are connected in parallel, and then are connected with a switching control loop and a switching coil LC2 of a standby power supply in serial; a positive bus of a DC (Direct Current) power supply is connected with a control power supply fuse FU1 in serial, passes through the previous two series circuits, and passes through a control power supply fuse FU2, and then is connected into a negative bus of the DC power supply, to form a switching loop; a main power supply breaker auxiliary contact QF1-2 and a standby power supply auxiliary contact QF2-2 are connected in serial and are connected with a circuit which is composed of a main power supply power direction relay KW1 and a standby power supply power direction relay KW2 which are connected in serial in parallel; the switching sheet XB1 is connected with a main power supply breaking coil LT1 in serial; and the switching sheet XB2 is connected with a standby power supply breaking coil LT2 in serial.

Description

technical field [0001] The invention relates to a safety automatic control device for an electric power system, in particular to a safety automatic control system for preventing a 30° angle difference loop. Background technique [0002] At present, the 35kV substation of the power system generally adopts the power supply mode of one master and one backup. Under normal circumstances, the substation is powered by the main power supply, and the backup power switch is in a hot standby state. When the main power supply in operation has a permanent failure, the substation quickly and automatically pulls the main power switch through the backup power automatic input device (referred to as standby self-switching), and closes the backup power switch to restore power to the substation. This mode of operation greatly improves the power supply reliability of the power system. [0003] However, the above method is not feasible for a substation (such as a 35kV substation) with a 30° pha...

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Problems solved by technology

[0003] However, the above method is not feasible for substations with a 30° phase angle difference between the main and backup power sources (such as 35kV substations)

Because if the main and backup power sources are connected through the busbar of the substation, a large circulating current will be generated, far exceeding the current-carrying limit of the power equipment (the circulating current is 4.7 times the rated current of the transformer), and it is very easy to cause damage to the equipment.

In order to avoid this situation caused by the wrong connection of the backup power switch, the backup power switch is generally in the cold standby state during operation. The function of being put into operation quickly requires operators to go to the site to perform switching operations, which takes a long time to restore power supply, and the reliability of power supply in substations is greatly restricted

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