Researchers Fan Hongtao and Zhang Yonggang from Xiangyang Power Supply Company of State Grid pointed out in the 2nd issue of "Electrical Technology" magazine in 2016 that in 220kV intelligent substations, 220kV circuit breakers are generally equipped with dual intelligent terminals, which are equivalent to two independent operating boxes.
Compared with the single operating box with double trip function in conventional integrated power substations, the implementation method of its anti-trip circuit is different. Based on the analysis of the anti-trip circuit of the conventional operating box, this paper proposes a method for implementing the anti-trip circuit of the dual intelligent terminal.
According to the "12th Five-Year Plan" power grid development plan of State Grid Corporation, all new substations with voltage levels of 110kV and above are intelligent substations, and traditional integrated power substations will be gradually transformed into intelligent substations. The 220kV circuit breaker mechanism of the intelligent substation is generally equipped with dual intelligent terminals. The function of the dual intelligent terminal in the operating circuit is equivalent to two independent operating boxes.
Compared with the traditional single operating box with double trip function, the independence of the dual intelligent terminal operating circuit is stronger. Article 8.1.2 of Q/GDW161-2007 "Standardized Design Specifications for Line Protection and Auxiliary Devices" stipulates that the anti-tripping function of the circuit breaker should be realized by the circuit breaker body mechanism.
Therefore, according to the requirements of relevant standards and specifications for high-voltage circuit breakers, the new 220kV circuit breaker body is equipped with an anti-tripping circuit, and the anti-tripping circuit of the operating box is usually not used. However, during the intelligent transformation construction of some old comprehensive self-powered stations, it was found that many older circuit breaker bodies did not have an anti-tripping function. The anti-tripping function of this type of circuit breaker must be realized by an intelligent terminal.
1 Analysis of the principle of the anti-tripping circuit of the traditional double-tripping operating box
The function of the anti-tripping circuit is: when the manual closing or reclosing reaches a fault, and the closing pulse is long, or the closing contact is stuck, in order to prevent the circuit breaker from being damaged by multiple closings after the circuit breaker is tripped, an anti-tripping circuit is provided. The operating box used in the traditional 220kV circuit breaker mechanism has two sets of phase tripping circuits and one set of phase closing circuits. The operating principle of the anti-tripping circuit of the operation box is shown in Figure 1 (the circuit is appropriately simplified). When the circuit breaker trips due to manual closing or reclosing to the fault, TJa is connected, 11TBIJa of the tripping circuit is tripped and maintained, 12TBIJa (22TBIJa is the second group of tripping) contacts are closed, 1TBUJa is started, 2TBUJa is started after 1TBUJa is actuated, and 2TBUJa is self-retained through its own contacts in the presence of the closing pulse, so the normally closed contacts of the two groups of relays in series in the closing circuit are disconnected, cutting off the closing circuit to avoid multiple tripping of the circuit breaker. Through the above analysis, we can see that both sets of tripping circuits have anti-tripping functions.
2 Characteristics of the anti-tripping circuit of the dual intelligent terminal
The 220kV circuit breaker of the intelligent substation is equipped with a dual intelligent terminal, and both sets of intelligent terminals have independent and complete tripping and closing circuits. Because the circuit breaker has only one set of tripping coils, the main function of the first set of intelligent terminals in cooperation with the circuit breaker mechanism is the first set of tripping and closing; the main function of the second set of intelligent terminals is the second set of tripping, and it is independent of the first set of operating boxes, and its closing circuit function is not used.
Therefore, the implementation of the anti-tripping function of the second set of tripping circuits is very different from that of the single operating box. As shown in Figure 2, we first analyze the anti-tripping circuit of the first set of intelligent terminals. The implementation method is: when the tripping pulse exists (TJa is connected) or the manual is disconnected, and the closing pulse has not returned, the TBJa or manual tripping contact STBJa connected in series in the tripping circuit is connected, and the anti-tripping relay 1TBJUa is started. The normally open contact of 1TBJUa is connected and self-maintained, and the normally closed contact disconnects the closing circuit, realizing the anti-tripping function of the first set of intelligent terminals.
However, when the second set of intelligent terminals trips, because the circuit breaker closing circuit is connected to the first set of intelligent terminals, and the second set of tripping circuits is independent of the first set of intelligent terminals, the anti-tripping relay 1TBJUa of the closing circuit will not be able to start, and its anti-tripping function will not be realized.
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