CN203800568U - Parallel type generator circuit breaker - Google Patents

Abstract

The utility model discloses a parallel type generator circuit breaker. The parallel type generator circuit breaker includes a current-carrying loop and a cut-off loop which is connected in parallel with the current-carrying loop; when a short-circuiting fault occurs, the current-carrying loop acts rapidly, so that an arcing fracture can be formed; the arc voltage of the fracture is utilized to transfer fault current to the cut-off loop; and the cut-off loop directly cuts off the fault current or fast performs current limiting on the fault current and cuts off the fault current. According to the parallel type generator circuit breaker of the utility model, the current-carrying loop includes a load switch unit with dozens of micro ohm conduction impedance, so that it can be ensured that more than 90% of the rated current of a system can pass through the unit, and therefore, the heat loss of the generator circuit breaker GCB device can be decreased under rated condition; and at the same time, the current-carrying loop has a quick-acting ability, and generally, the current-carrying loop can be selectively cut off thoroughly in two power frequency cyclic waves after a fault occurs; the current-carrying loop can have high arcing voltage after a contact is switched off, so that rapid transfer of the fault current can be urged.

Description

A Parallel Generator Outlet Circuit Breaker

technical field

The utility model belongs to the field of high-voltage and large-capacity circuit breakers, in particular to a parallel-connected generator outlet circuit breaker.

Background technique

With the increase of demand for electricity load, the development trend of various types of generators is to develop in the direction of high parameters, large capacity and high efficiency.

Based on the requirements of plant power reliability and quick fault removal, more and more power plants are considering installing generator circuit breakers (Generator Circuit Breaker-GCB), but supercritical, ultra-supercritical thermal power units and ultra-large hydropower, The short-circuit current at the outlet of nuclear power units is huge, and the breaking capacity of GCB products at home and abroad does not meet the requirements, which brings obstacles to the protection of generator outlets.

The parallel connection technology of circuit breakers based on high-coupling split reactors can double the current-carrying capacity and short-circuit current breaking capacity of circuit breakers under existing conditions. However, the coupling reactor in the above parallel scheme must bear the rated current of the system for a long time. As a result, there are strict restrictions on the calorific value and heat dissipation capacity of the coupling reactor, which will inevitably result in a large overall volume and high cost of the reactor and the circuit breaker; at the same time, the resistance of the reactor will also introduce additional operating costs for the parallel circuit breaker. Therefore, the characteristics of parallel GCBs based on high-coupling split reactors also limit their application in generator outlet protection.

Utility model content

Aiming at the defects of the prior art, the utility model provides a parallel generator outlet circuit breaker, the purpose of which is to provide a large-capacity, ultra-large-capacity generator outlet circuit breaker, which solves the problems existing in the prior art. Insufficient circuit breaker capacity, difficulty in balancing current-carrying capacity and breaking capacity.

The utility model provides a parallel generator outlet circuit breaker, which includes a current-carrying circuit and a breaking circuit connected in parallel with the current-carrying circuit; the breaking circuit includes: a first coil and a second coil coupled inversely Two coils, a first circuit breaker connected at one end to the outgoing line end of the first coil, and a second circuit breaker connected at one end to the outgoing line end of the second coil; the incoming line end of the first coil and the The incoming line end of the second coil is connected as the incoming line end of the breaking circuit; the other end of the first circuit breaker is connected with the other end of the second circuit breaker as the outgoing line end of the breaking circuit .

Wherein, the first coil and the second coil are air-core inductance coils.

Wherein, the turn ratio of the first coil to the second coil is 1:k, and k is a positive real number greater than or equal to 1.

Wherein, the current-carrying circuit includes: a fast switch, one end of which is connected to the incoming line end of the breaking circuit, and the other end is connected to the outgoing line end of the breaking circuit.

When the utility model is in normal operation, most of the system current passes through the current-carrying circuit; when a short-circuit fault occurs, the current-carrying circuit quickly moves to form an arcing fracture, and the current is transferred to the breaking circuit by using the arc voltage of the fracture. Break the fault current directly or quickly limit the current to realize the breaking of the fault current, and quickly transfer the fault current.

Description of drawings

Fig. 1(a) is the topology principle of the parallel GCB provided by the utility model, in which the turns ratio of the two coils of the HCSR is 1:1.

Fig. 1(b) is the topology principle of the parallel GCB provided by the utility model, in which the turns ratio of the two coils of the HCSR is 1:k.

Figure 2(a) shows the structural principle of the HCSR provided by the utility model and a way of entering and exiting the line.

Figure 2(b) shows the structural principle of the HCSR provided by the utility model and a way of entering and exiting the line.

Fig. 3(a) Schematic diagram of voltage distribution under the original way of incoming and outgoing lines.

Figure 3(b) Schematic diagram of voltage distribution in the original way of incoming and outgoing lines.

Detailed ways

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

The utility model provides a parallel GCB device; the device includes two parts, a current-carrying circuit and a breaking circuit. During normal operation, most of the system current passes through the current-carrying circuit; when a short-circuit fault occurs, the current-carrying circuit quickly moves to form an arcing fracture, and uses the arc voltage of the fracture to transfer the current to the breaking circuit, and the breaking circuit directly breaks the fault The breaking of the fault current is realized after current or fast current limiting.

The current-carrying circuit in the utility model is a load switch unit with a conduction resistance of tens of microohms, which can ensure that more than 90% of the system rated current passes through the unit, reducing the heat loss on the GCB device under rated working conditions; The current circuit should have the ability to act quickly, and generally it can be selected to break to the full opening distance within 2 power frequency cycles after the fault occurs; the current-carrying circuit should choose a switch type other than a vacuum switch to ensure that the current-carrying transfer unit after the contact is opened It has a higher arcing voltage, which promotes the rapid transfer of fault current.

The breaking circuit of the utility model bears only a small part of the current under the non-breaking working condition, and bears all the breaking current of the GCB device under the breaking working condition. The breaking circuit is realized by "parallel circuit breaker based on High Coupled Split Reactor-HCSR". The HCSR consists of two highly anticorrelated coupled coils. The incoming wire ends of the two HCSR coils are connected as the incoming wire end of the breaking circuit; the outgoing wire ends of the two HCSR coils are respectively connected in series with a circuit breaker, and the other ends of the two circuit breakers are connected as the outgoing wire end of the breaking circuit. When both circuit breakers in the breaking circuit are in the conduction state, most of the magnetic fields of the two coils of the HCSR cancel each other out, and the breaking circuit is only manifested as the leakage inductance of the double coils of the HCSR, the resistance of the double coils of the HCSR and the parallel circuit breaker resistance between contacts. Since the above-mentioned impedance is much greater than the impedance when the contacts of the current-carrying circuit are closed, the unit only bears a small part of the system's rated current, and the design requirements for the steady-state temperature rise of the HCSR are low, and only the dynamic and thermal stability design requirements of the HCSR coil need to be considered.

In this utility model, the current-carrying circuit 1 has a small on-resistance, and at the same time, the current-carrying circuit 1 should be equipped with an operating mechanism capable of quick breaking action, and the current-carrying circuit is required to adopt a high-pressure arc extinguishing unit to ensure that the current-carrying circuit 1 The current unit contacts have a higher arcing voltage after breaking. The current-carrying circuit 1 includes: a fast switch, one end of which is connected to the incoming line end of the breaking circuit 2 , and the other end is connected to the outgoing line end of the breaking circuit 2 . Specifically, the fast switch can be a switch with SF6 gas as the insulation and arc-extinguishing medium, or a switch with compressed air or other gases as the insulation and arc-extinguishing medium. Vacuum arc-extinguishing switches are avoided to ensure that the switch has a high arc rate. Voltage; the fast switch should have the characteristics of contact opening distance and relatively small operating mass, so as to ensure that the mechanism can operate quickly.

The HCSR in the breaking circuit of the utility model is an air-core inductance coil with an average turn ratio of 1:k (k is a positive real number greater than or equal to 1). When the number of turns of 1:1 is used, the two coils can be designed in an almost completely symmetrical manner - the two coils pass through currents of complete size and phase, and the magnetic flux generated by the current cancels each other in the area where the coils are located; when using 1: When the number of turns of k is designed, the cross-sections of the two coil conductors and the magnitudes of the passing currents are different. It can be designed that the outer dimensions of the adjacent encapsulating coils are approximately the same, and the turns ratio is designed to be about 1:k. It is k:1, which ensures that the magnetic fluxes of the two coils of the HCSR cancel each other out in the area where the coils are located.

The breaking circuit of the utility model can work in two modes of current equalizing/limiting breaking and forced current limiting breaking. When the breaking circuit works in the current-sharing/current-limiting breaking mode, the ratio of the turns of the two coils of the HCSR is 1:1. At this time, the parallel circuit breaker can use one set of operating mechanism or two sets of separate operating mechanisms. If the arc extinguishing chamber of the parallel circuit breaker can extinguish the arc at the same current zero-crossing point, the HCSR will ensure that the current passing through the two parallel branches is distributed in a ratio of 1:1, that is, the breaking circuit works in a current-sharing condition; if The arc extinguishing chamber of the parallel circuit breaker can extinguish the arc at different current zero-crossing points. After an arc extinguishing chamber crosses zero and extinguishes the arc first, the HCSR is only equivalent to a current-limiting inductance and resistance. When the inductance is selected as the maximum fault current, the generator The short-circuit impedance from the outlet to the short-circuit point can ensure that the power frequency component of the fault current is limited to the breaking capacity of a single circuit breaker, and then the fault current breaking is completed by the rear-opening circuit breaker.

When the breaking circuit works in the forced current limiting breaking mode, the turns ratio of the two coils of HCSR can be 1:1 or 1:k. In this working mode, the operating mechanism of a circuit breaker (such as 4) is forced to open first. After the current in the corresponding circuit breaker crosses zero or is transferred to another branch circuit breaker, HCSR is only equivalent to a current-limiting inductance and resistance . Then the power frequency component of the generator outlet fault current will be limited to 50% (corresponding to the turns ratio of HCSR1:1) or 1/(1+k) or k/(1+k) (corresponding to the turns ratio of HCSR1:k ), and then the fault current breaking is completed by the rear breaking circuit breaker (eg 5).

Under the above-mentioned various breaking modes and various breaking conditions, the coil resistance of HCSR will accelerate the attenuation of the DC component of the fault current and the appearance of the zero point of the fault current.

Fig. 1(a) is a topology implementation of the parallel GCB of the present invention. As shown in Figure 1, the parallel GCB includes a current-carrying circuit 1 and a breaking circuit 2. The current-carrying circuit adopts a high-voltage switch that can carry a large rated current for a long time and can act quickly to form a fracture gap when needed. The current-carrying circuit should have a small closed impedance, so that it can carry most of the system current when the generator outlet system is in normal operation, and ensure that the temperature rise of the unit does not exceed the material temperature rise limit; at the same time, the current-carrying circuit has a fast action After a short-circuit fault occurs, the operating mechanism of the unit should be able to quickly move to form a fracture, and use the higher fracture arc voltage to transfer the fault current to the breaking circuit of the parallel GCB.

The breaking loop 2 in the topological implementation form shown in FIG. 1 includes an HCSR with a turn ratio of 1:1 or 1:k and two circuit breakers 23 , 24 . HCSR consists of two reversely coupled coils wound coaxially and in opposite directions. Each coil is composed of a plurality of concentric cylindrical envelopes connected in parallel. Take the HCSR coil in which each coil is encapsulated and connected in parallel with two coils as shown in FIG. 2 as an example to illustrate the structure and connection method of the HCSR used in the present invention. In Figure 2, the 4 coils of the HCSR are coaxially nested and wound, in which all the odd-numbered packages have the same winding direction, all the even-numbered packages have the same winding direction, and the winding directions between the odd and even packages are opposite. All odd packets are connected in parallel to form one coil, and all even packets are connected in parallel to form another coil. Due to the small difference in the diameters of adjacent coils, corresponding to the topological requirements shown in Figure 1(a), the average number of turns of the two coils of the HCSR is close, almost 1:1, but the current direction in the coils is opposite; corresponding to Figure 1(b) The shown topology requires that the average number of turns of the two coils of the HCSR is about 1:k, but the direction of the current in the coil is opposite; kind.

As shown in Figure 2, 9, 10, 11, and 12 are the upper connection wires enclosed by four coils from inside to outside, and 13, 14, 15, and 16 are the lower connection wires enclosed by four coils from inside to outside. 17 is the insulation and reinforcement layer between the packages. 17 Several combinations of various insulating film materials, glass fibers impregnated with epoxy resin, epoxy resin pouring materials, air and other substances can be selected to achieve reinforcement and insulation between packages.

The first way of entering and exiting the HCSR is shown in Figure 2(a). Connect 9 to 12 together as the common incoming terminal 6 of the two coils of the HCSR, connect 13 and 15 as an outgoing terminal 7, and connect 14 and 16 Connect as an outgoing line terminal 8; the second incoming and outgoing line method is shown in Figure 2(b), connect 9, 11, 14, and 16 together as the common incoming line end 6 of the two coils of HCSR, connect 10, 12 As an outlet terminal 7, 13, 15 is connected as an outlet terminal 8. As shown in Fig. 2(a), the first type of inlet and outlet mode, the inlet and the wire ends are respectively located on the upper and lower sides of the coil, and the design of the connection between the HCSR and the current-carrying circuit 1 and the first circuit breaker 23 and the second circuit breaker 24 is simple; Fig. 2 (b) The connection design of the connection between the incoming and outgoing line HCSR and the current-carrying circuit 1 and the first circuit breaker 23 and the second circuit breaker 24 is complicated. As shown in Figure 3(a), when the first circuit breaker 23 is turned off and the second circuit breaker 24 is turned on, the point where the second circuit breaker 24 is located is set at 0 potential, and the voltage drop of a single coil is set to be V, then The voltages of 9 and 10 are both V, and the voltage of 12 is 2V, so the voltage between adjacent coils in Figure 3(a) is 0-2V from top to bottom; similarly, the voltage between adjacent coils in Figure 3(b) is from V from top to bottom. It can be seen that the first way of incoming and outgoing lines is simple and easy to connect, but the insulation design between adjacent envelopes is relatively difficult; the second way is responsible for the connection of incoming and outgoing lines, but the insulation design between adjacent envelopes is simple. The specific design can determine the choice of the two entry and exit methods according to the applied voltage level and on-site installation space.

The first circuit breaker 23 and the second circuit breaker 24 in the breaking circuit can adopt large-capacity vacuum circuit breakers, SF ₆ circuit breakers or other types of breaking devices, and can also use a combination of different types of breaking devices.

When the first circuit breaker 23 and the second circuit breaker 24 use the same circuit breaker, the turns ratio of the HCSR is selected as 1:1, as shown in FIG. 1( a ). The first circuit breaker 23 and the second circuit breaker 24 can be operated by respective independent mechanisms, or can be operated by the same mechanism. When operated by the same mechanism, the first circuit breaker 23 and the second circuit breaker 24 act simultaneously. If the first circuit breaker 23 and the second circuit breaker 24 are turned on at the same time, the two coils of the HCSR ensure that the current in the first circuit breaker 23 and the second circuit breaker 24 is equally divided; if the first circuit breaker 23 and the second circuit breaker 24 are off The difference in arc conditions causes only one arc extinguishing chamber to pass current, so a single coil of HCSR can limit the fault current to the breaking capacity of a single arc extinguishing chamber. When using their own independent operating mechanisms, one circuit breaker can be disconnected first. Under this working condition, HCSR limits the power frequency component of the fault current to 50%, which can reduce the impact of the fault current on the fault current before breaking through zero. The impact of the system; if operated at the same time, the effect is the same as that of the same operating mechanism.

When the first circuit breaker 23 and the second circuit breaker 24 operate with different circuit breakers, the HCSR can select a turn ratio of 1:1 or 1:k. The first circuit breaker 23 and the second circuit breaker 24 use independent operating mechanisms. In this configuration mode, the breaking circuit works in the active current limiting mode, that is, after the current is completely transferred to the breaking circuit, one of the first circuit breaker 23 and the second circuit breaker 24 should act quickly to close the fault The current is completely transferred to another circuit breaker, and the power frequency component of the fault current can be limited to about 50% or 1/(1+k) or k/(1+ k).

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements and modifications made within the spirit and principles of the utility model Improvements and the like should all be included within the protection scope of the present utility model.

Claims (4)

1. a generator outlet circuit breaker for parallel connection type, is characterized in that, comprises current loop (1) and cut-offs loop (2) with described current loop is connected in parallel;

The described loop (2) of cut-offfing comprising: the first coil (21) and second coil (22) of inverse correlation coupling, the first circuit breaker (23) that one end is connected with the leading-out terminal of described the first coil, and the second circuit breaker (24) of being connected with the leading-out terminal of described the second coil of one end;

After being connected, the end of incoming cables of the end of incoming cables of described the first coil (21) and described the second coil (22) cut-offs the end of incoming cables in loop described in conduct;

After being connected with the other end of described the second circuit breaker (24), cut-offs the other end of described the first circuit breaker (23) leading-out terminal of loop (2) described in conduct.

2. generator outlet circuit breaker as claimed in claim 1, is characterized in that, described the first coil (21) and the air-core inductance of described the second coil (22) for inverse correlation coupling.

3. generator outlet circuit breaker as claimed in claim 2, is characterized in that, the turn ratio of described the first coil and described the second coil is 1: k, k is more than or equal to 1 arithmetic number.

4. the generator outlet circuit breaker as described in claim 1-3 any one, is characterized in that, described current loop (1) comprising: high-speed switch, and described in being connected to, its one end cut-offs the end of incoming cables in loop, described in being connected to, cut-offs the other end leading-out terminal in loop.