Analysis of Dual Intelligent Terminal Anti Jumping Circuit in Intelligent Substation

Researchers Fan Hongtao and Zhang Yonggang from State Grid Xiangyang Power Supply Company wrote in the second 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 operation boxes. Compared with the conventional integrated self station with double jump function single operation box, its anti jump circuit implementation method is different. Based on the analysis of the anti bounce circuit of the conventional operation box, this article proposes a method for implementing a dual intelligent terminal anti bounce circuit. According to the "12th Five Year Plan" for power grid development of State Grid Corporation of China, newly built substations with voltage levels of 110kV and above are all intelligent substations, and traditional integrated substations will gradually be transformed into intelligent substations. The 220kV circuit breaker mechanism of intelligent substations is generally equipped with dual intelligent terminals. The dual intelligent terminal's function in the operation circuit is equivalent to two independent operation boxes. Compared with traditional single operation boxes with double jump function, the dual intelligent terminal operation circuit has stronger independence. According to Article 8.1.2 of Q/GDW161-2007 "Standardization Design Specification for Line Protection and Auxiliary Devices", the anti tripping function of circuit breakers should be implemented by the circuit breaker body mechanism. Therefore, according to the requirements of relevant standards and specifications for high-voltage circuit breakers, the newly manufactured 220kV circuit breaker mechanism body is equipped with an anti trip circuit, and the anti trip circuit of the operation box is usually not used. However, during the intelligent transformation and construction process of some old comprehensive self stations, it was found that many older circuit breaker mechanisms do not have anti tripping functions. The anti tripping function of such circuit breakers must be implemented by intelligent terminals. The principle analysis of the traditional anti jump circuit with a double jump operation box shows that the function of the anti jump circuit is to prevent the circuit breaker from tripping and repeatedly closing when the fault occurs due to manual closing or reclosing, and the closing pulse is long or the closing contact is stuck. Therefore, an anti jump circuit is provided to prevent the circuit breaker from tripping and then closing multiple times, causing damage to the circuit breaker. The operation box used in traditional 220kV circuit breaker mechanisms has two sets of phase separated tripping circuits and one set of phase separated closing circuits. The operating principle of the anti trip circuit of the control box is shown in Figure 1 (the circuit has been appropriately simplified). When the fault is manually closed or overlapped, the circuit breaker trips, and TJa is connected. The 11TBIJa of the trip circuit trips and remains, and the 12TBIJa (22TBIJa is the second group trip) contacts are closed, starting 1TBUJa. After 1TBUJa is activated, 2TBUJa is started, and 2TBUJa self holds through its own contacts in the presence of a closing pulse. Therefore, the normally closed contacts of these two sets of relays connected in series to the closing circuit are disconnected, cutting off the closing circuit and avoiding multiple tripping and closing of the circuit breaker. From the above analysis, we can see that both sets of trip circuits have anti trip functions. The characteristics of the dual intelligent terminal anti tripping circuit are that the 220kV circuit breaker in the intelligent substation is equipped with dual intelligent terminals, and both sets of intelligent terminals have independent and complete tripping and closing circuits. Because the circuit breaker only has one combination of switch coils, the main function of the first set of intelligent terminals in coordination with the circuit breaker mechanism is to trip and close the first group; The main function of the second set of intelligent terminals is to trip the second group, which is independent of the first group of operation boxes, and its closing circuit function is not used. Therefore, the implementation of the anti tripping function of the second group trip circuit is significantly different from that of a single operation box. As shown in Figure 2, we first analyze the anti trip circuit of the first set of intelligent terminals. The implementation method is: when there is a trip pulse (TJa connected) or manual disconnection, and the closing pulse does not return, the TBJa or manual tripping contact STBJa connected in series in the trip circuit is connected, and the anti trip relay 1TBJUa is activated. The normally open contact of 1TBJUa is connected and self holds, and the normally closed contact is disconnected from the closing circuit, achieving the anti trip function of the first set of intelligent terminals. However, when the second set of intelligent terminals trips, due to the circuit breaker closing circuit being connected to the first set of intelligent terminals and the second set of tripping circuits being independent of the first set of intelligent terminals, the anti trip relay 1TBJUa of the closing circuit will not be able to start, and its anti trip function will not be realized.