CN101814402A - Parallel type circuit breakers based on tightly coupled air reactor - Google Patents

Abstract

The invention relates to a parallel circuit breaker based on a tightly coupled air-core reactor, which belongs to the field of high-voltage large-capacity circuit breaker devices. The current input ends of the two arms of the tightly coupled air-core reactor are on the same side of the reactor, and are short-circuited. They are connected to the system by welding with the terminal board. The other end of the circuit breaker is short-circuited and connected to the system, so that the entire parallel circuit breaker device based on the tightly coupled air-core reactor is connected in series to the system, and the terminal board at the output end of the tightly coupled air-core reactor is supported by post insulators and fixed on the platform. The invention connects circuit breakers in parallel by tightly coupling air-core reactors so that the short-circuit current can be doubled and the overall breaking capacity is improved.

Description

Parallel circuit breaker based on tightly coupled air-core reactor

technical field

The invention relates to a parallel circuit breaker based on a tightly coupled air-core reactor, belonging to the field of high-voltage and large-capacity circuit breaker combination devices.

Background technique

With the rapid development of the power system, the level of short-circuit current increases sharply, and the interrupting capacity of the original switchgear will not meet the requirements; A generator outlet circuit breaker (GCB) is installed, but the short-circuit current at the outlet of large generators is large, and the breaking capacity of domestic GCB products does not meet the requirements. Even if imported products meet the requirements, their price is extremely expensive, which brings obstacles to the protection of generator outlets.

The short-circuit current of the power system is also increasing, especially after the short-circuit current of the 500kV substation increases sharply, resulting in insufficient breaking capacity of the installed equipment in the substation. The 500kV short-circuit current of Guangdong and Fujian power grids will reach 70kA, and the short-circuit current of the 220kV system may exceed 80kA, which exceeds the maximum breaking capacity of the domestic circuit breaker with the largest breaking capacity of 63kA. Although there are circuit breakers with a breaking capacity of more than 100kA in foreign countries, the number of this type of equipment produced internationally is small, and the price must be high.

At present, most of the circuit breakers with high voltage level are gas circuit breakers. The most direct way to solve the excessive short-circuit current is to improve the breaking capacity of the existing gas circuit breakers. However, it is technically very difficult to increase the breaking capacity of gas circuit breakers from the conventional 63kA level to hundreds of kiloamperes in a short period of time.

The circuit breaker parallel technology can double the interrupting capacity of the circuit breaker. Improving the breaking capacity of the circuit breaker by connecting multiple arc extinguishing chambers in parallel can double the current-carrying capacity and short-circuit current breaking capacity of the circuit breaker under the existing conditions, so it is a feasible solution. However, directly connecting circuit breakers in parallel has the problem of different phases of operation, and still cannot solve the problem of excessive short-circuit current; realizing parallel connection of circuit breakers with a synchronous holding device not only has low synchronization reliability, but also has a high cost, so it has not been promoted so far ; Although the parallel connection method of directly series inductors can ensure a better current sharing effect, the inductance will increase the normal operating impedance, greatly reduce the transmission capacity of the line, and increase the cost of use. Therefore, the above-mentioned parallel scheme has poor reliability and cannot meet the requirements of parallel breaking.

Although the Chinese patent 200710052947.7 "Parallel Circuit Breaker" mentions the parallel connection technology of circuit breakers, it is limited to a conceptual design, and its reactor components are limited to iron core reactors, and there are iron cores such as saturation and heat generation during operation. Inherent disadvantages of reactors.

Although the Chinese patent 200810197118.2 "air-core coupling reactor" has the design concept of a parallel circuit breaker component - a coupling reactor, heat dissipation is not considered in the specific structure, which will inevitably lead to serious consequences in actual operation, so it is not feasible.

Contents of the invention

The purpose of the present invention is to provide a parallel circuit breaker based on a tightly coupled air-core reactor. The circuit breaker utilizes a tightly coupled air-core reactor with high coupling degree and low energy consumption under normal working conditions, and is used in combination with the circuit breaker to effectively Realize the automatic current sharing and current limiting function of the reactor, so as to realize the true parallel connection of the circuit breaker, and double the capacity of the circuit breaker to withstand the rated current and short-circuit current.

The technical solution of the present invention is: a parallel circuit breaker based on a tightly coupled air-core reactor, which is characterized in that it is composed of a tightly coupled air-core reactor and a parallel circuit breaker, and its connection mode is: the current input of the two arms of the tightly coupled air-core reactor The ends are on the same side of the reactor and short-circuited. They are connected to the system by welding with the terminal board. The current output ends of the two arms are respectively connected to two circuit breakers after being welded with the terminal board. The other end of the circuit breaker is short-circuited. And connected to the system, so that the entire parallel circuit breaker device based on the tightly coupled air-core reactor is connected in series to the system, and the terminal board at the output end of the tightly coupled air-core reactor is supported by post insulators and fixed on a prefabricated platform.

The above-mentioned parallel circuit breaker based on the tightly coupled air-core reactor is characterized in that: the parallel circuit breaker is a high-voltage large-capacity gas interrupter circuit breaker, a total of two, connected in parallel.

The above-mentioned parallel circuit breaker based on tightly coupled air-core reactors is characterized in that: the tightly coupled air-core reactors are in the shape of cylinders, and are respectively composed of terminal boards, post insulators and several single-layer inductance coils.

The above-mentioned shunt circuit breaker based on tightly coupled air-core reactors is characterized in that all single-layer inductance coils are wound by a single wire or split wires, arranged in layers, and there are windings between turns between layers. Insulation, these inductive coils are coaxially arranged, share a central axis, and have equal turns, so as to achieve the purpose of tight coupling.

The above-mentioned parallel circuit breaker based on tightly coupled air-core reactors is characterized in that: when the current flows through all the inductance coils, the directions of the magnetic fields induced in the adjacent inductance coils are opposite, and all the inductance coils that induce the same magnetic field direction Parallel connection is equivalent to one arm of a tightly coupled air-core reactor. All single-layer inductance coils in each arm have the same winding direction and are connected in parallel with each other.

The above-mentioned parallel circuit breaker based on tightly coupled air-core reactors is characterized in that: each layer of tightly coupled air-core reactors has only inductance coils with the same winding direction, and the winding directions of adjacent inductive coils are opposite, so that tightly coupled air-core The innermost layer of the reactor is the first layer, and the outermost layer is the last layer. The first layer and the second layer are interlayer insulation and voltage-resistant materials. The first layer, the insulating material and the second layer are a package The envelope, that is, the first envelope, between the envelopes is a cooling air channel, and so on until the outermost envelope.

The above-mentioned parallel circuit breaker based on the tightly coupled air-core reactor is characterized in that the inductance coil of the tightly coupled air-core reactor is an air-core inductance coil, thereby ensuring good linearity.

The beneficial effects of the present invention are: the parallel circuit breaker device based on the tightly coupled air-core reactor doubles the breaking short-circuit current level of the circuit breaker at the same voltage level, improves the overall breaking capacity of the system, and the present invention operates under normal conditions. Under working conditions, it will basically not bring additional impedance to the system loop, and the impact on the system is minimal. When a fault occurs, the electromagnetic reaction is used to realize the automatic current sharing of the two branches, so as to realize the automatic parallel connection of the circuit breaker. Guarantee the normal breaking of the single-branch circuit breaker, and achieve the purpose of breaking the large short-circuit current of the small-parameter circuit breaker.

Description of drawings

Fig. 1 is a schematic diagram of the winding method of two single-layer inductance coils in one package of the tightly coupled air-core reactor of the present invention.

Fig. 2 is a top view of the positional relationship between two single-layer inductance coils and insulating and voltage-resistant materials in one package of the tightly coupled air-core reactor of the present invention.

Fig. 3 is an axial sectional view of the positional relationship between the two single-layer inductance coils and the insulating and voltage-resistant material in one package of the tightly coupled air-core reactor of the present invention and the connection mode of the conductors at the current input and output terminals.

Fig. 4 is a mid-axis sectional view of a parallel circuit breaker based on a tightly coupled air-core reactor with only two envelopes according to the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Notes in Figure 1: 1, 2, 3, and 4 are all single-layer inductance coils.

Notes in Fig. 2: 5-insulation and voltage-resistant material, 6-two single-layer inductance coils wound in opposite directions.

Marking description in Figure 4: 7-insulation withstand voltage material, 8-air, 9, 11, 13, 15-current input terminals, 10, 12, 14, 16-current output terminals, 17, 19-circuit breaker input terminals, 18, 20-circuit breaker output terminal.

As shown in Figure 1, the two single-layer inductance coils 1-2, 3-4, 1-2, 3-4 in one package of the tightly coupled air-core reactor are wound in opposite directions, so that when the single-layer inductance coil 1, the single-layer When the 3 terminals of the inductance coil are connected with the current in the same direction, the directions of the magnetic flux generated in the two single-layer inductance coils are opposite. The conductor used in each single-layer inductance coil is either a single wire, or a split winding and winding.

As shown in Figure 2, the inter-turn insulation of the coil and the insulation withstand voltage level of the interlayer insulation are determined according to the voltage level of the system where the coil is located. The insulation and voltage resistance material 5 and the two single-layer inductance coils 6 wound in opposite directions are collectively called a encapsulation.

As shown in Figure 3, in one package, in order to reduce the requirements for the interlayer insulation of the two single-layer inductor coils, it is stipulated that the current flow direction of the two coils is from the input end to the output end, that is, from the single-layer inductor coil 1 to the single-layer inductor The coil 2 flows from the single-layer inductive coil 3 to the single-layer inductive coil 4, or both flow from the output end to the input end; in this way, the voltage is as small as possible between the turns at the same or close position in the axial direction. Since the two coils are wound in opposite directions, the magnetic fluxes generated by the two coils cancel each other out when the two coils pass through the currents of equal magnitude.

As shown in Figure 4, the insulating and withstand voltage material is between the current input end 9 and the current output end 10, an envelope is formed between the current input end 11 and the current output end 12, and an enclosure is formed between the current input end 13 and the current output end 14. It is an insulating and withstand voltage material, an enclosure is formed between the current input terminal 15 and the current output terminal 16, and a cooling air passage is between the two enclosures. The horizontal distance of the air passage is related to the power consumption of the tightly coupled air-core reactor. The current input terminal 9, current input terminal 11, current input terminal 13, and current input terminal 15 of the two envelopes are shorted to each other and then connected to one end of the system. The current output terminals of the two envelopes are shorted according to the same winding direction, and the winding direction is opposite. Then disconnect the principle connection, that is, the current output terminal 10 and the current output terminal 14 are short-circuited, which is the output terminal of one arm of the tightly coupled air-core reactor, connected to the input terminal 17 of a circuit breaker, and the current output terminal 12 and the current output terminal 16 is short-circuited, which is the output end of the other arm of the tightly coupled air-core reactor, and is connected with the input end 19 of another circuit breaker. The circuit breaker output terminals 18 and 20 of the two parallel circuit breakers are short-circuited and then connected to the other end of the system.

The inductance coil in the encapsulation is wound with aluminum (copper) wire, and after a certain external insulation treatment, it is soaked with epoxy resin and cured to form a whole.

The three-phase structure of the present invention is independent, and each phase includes a double-arm tightly coupled air-core reactor and two parallel gas circuit breakers. These devices have the same parameters and the same structure, so the principle can be explained for one phase. The type of parallel circuit breaker used in the device is not limited. When the voltage level is low, a commonly used vacuum circuit breaker can be used; when the voltage level is high, a widely used gas circuit breaker such as SF6 can be used.

In order to ensure the current sharing effect of the device, the impedance asymmetry rate of each arm of the tightly coupled air-core reactor used is within 3%. When the current flows into the parallel circuit breaker device based on double-arm tightly coupled air-core reactors, the two circuit breakers share the normal current and short-circuit current of the system. Due to the tightly coupled structure adopted, magnetic fluxes in opposite directions will be generated in each envelope of the tightly coupled air-core reactor. When the system is in normal operation, due to the symmetrical structure of the tightly coupled air-core reactor, the coupling inductance appears in the form of leakage reactance, its value is very small, and its loss can be ignored, and the parameters of the parallel circuit breaker connected with the tightly coupled air-core reactor are also consistent. , so as to ensure that the system current evenly flows through the two arms of the tightly coupled air-core reactor and the parallel circuit breaker.

When the system has a short-circuit fault, if the currents flowing through the two parallel circuit breakers are equal, the magnetic flux generated by the two branch currents in the two arms of the tightly coupled air-core reactor is equal in magnitude and opposite in direction, and the magnetic flux leakage appears to the outside, and the tightly coupled air-core reactance In the system, the reactor only behaves as leakage reactance, which will not increase the burden on the system; if the currents in the two paths are not equal, an alternating electromotive force will be induced in the two arms of the tightly coupled air-core reactor, which is determined by the law of electromagnetic induction It can be seen that the electromotive force makes the currents of the two branches tend to be equal, so that the tightly coupled air-core reactor can ensure that when the system is short-circuited, the circuit breakers of the two branches share the system current equally. The models of the parallel circuit breakers should be exactly the same, optional Set its rated capacity, short-circuit current and other parameters as one-half of the system parameters.

When the system has a short-circuit fault, if only one branch is turned on due to inconsistent actions of the arc extinguishing chambers of the parallel circuit breakers or the failure of a single circuit breaker, the tight-coupled air-core reactor presents a single-arm reactance, which is higher than the leakage reactance under the tight-coupled state. 2 to 3 orders of magnitude, which can effectively limit the current flowing through the single arm of the tightly coupled air-core reactor and the arc extinguishing chamber of a single circuit breaker.

Claims (7)

1. A parallel circuit breaker based on a tightly coupled air-core reactor, which is characterized in that it is composed of a tightly coupled air-core reactor and a parallel circuit breaker. On the same side and short-circuited, it is connected to the system by welding with the terminal board. The current output ends of the two arms are respectively connected to two circuit breakers after being welded to the terminal board, and the other end of the circuit breaker is short-circuited and connected to the system. Therefore, the entire parallel circuit breaker device based on tightly coupled air-core reactors is connected in series to the system, and the terminal board at the output end of the tightly coupled air-core reactors is supported by post insulators and fixed on a prefabricated platform. 2. The parallel circuit breaker based on tightly coupled air-core reactors according to claim 1, characterized in that: the parallel circuit breakers are high-voltage and large-capacity gas interrupter circuit breakers, and there are two in total, connected in parallel. 3. The parallel circuit breaker based on close-coupled air-core reactors according to claim 1, characterized in that the close-coupled air-core reactors are in the shape of a cylinder and are respectively composed of terminal boards, post insulators and several single-layer inductance coils. 4. The tightly coupled air-core reactor according to claim 3, characterized in that: all single-layer inductance coils are wound by a single wire or split wires, arranged in layers, with insulation between turns between layers, These inductive coils are arranged coaxially, share a central axis, and have equal turns. 5. The tightly coupled air-core reactor according to claim 3, characterized in that: when the current flows through all the inductance coils, the directions of the magnetic fields induced in the adjacent inductance coils are opposite, and all the inductance coils that induce the same magnetic field direction are connected in parallel , which is equivalent to one arm of a tightly coupled air-core reactor. All the single-layer inductance coils of each arm have the same winding direction and are connected in parallel with each other. 6. The tightly-coupled air-core reactor according to claim 3, characterized in that: each layer of the tightly-coupled air-core reactor has only inductance coils with the same winding direction, and the winding directions of adjacent inductance coils are opposite, so that the tightly-coupled air-core reactor The innermost layer of the device is the first layer, and the outermost layer is the last layer. The space between the first layer and the second layer is an interlayer insulation and voltage-resistant material. The first layer, the insulating material and the second layer are a package , that is, the first envelope, between the envelopes is a cooling air channel, and so on until the outermost envelope. 7. The tightly-coupled air-core reactor according to claim 3, characterized in that: the inductance coil of the tightly-coupled air-core reactor is an air-core inductance coil.

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