WO2021169520A1

WO2021169520A1 - Single-phase synchronous generator, single-phase power supply, arc-extinguishing system and arc-extinguishing method

Info

Publication number: WO2021169520A1
Application number: PCT/CN2020/137527
Authority: WO
Inventors: 芮骏; 李磊; 余银钢; 洪新春; 孔德鹏
Original assignee: 安徽一天电气技术股份有限公司
Priority date: 2020-02-26
Filing date: 2020-12-18
Publication date: 2021-09-02
Also published as: CN211701481U; WO2021169519A1

Abstract

A single-phase synchronous generator, a single-phase power supply, an arc-extinguishing system and an arc-extinguishing method. The single-phase synchronous generator comprises an inner stator assembly, a rotor assembly and an outer stator assembly arranged from inside to outside; the inner stator assembly comprises a first excitation winding for accessing a direct current; the rotor assembly is connected to an external motor by means of a coupling and rotates therewith, so that a first power generation winding inside the rotor assembly generates a three-phase alternating current, and the three-phase alternating current is rectified and provided to a second excitation winding outside the rotor assembly; and the outer stator assembly comprises a second power generation winding for providing a single-phase power supply output. The single-phase synchronous generator provides a compensation voltage of an appropriate phase and amplitude to a grounding transformer, and can reduce the voltage at a grounding fault point and extinguish an arc at the grounding fault point.

Description

Single-phase synchronous generator, single-phase power supply, arc suppression system and arc suppression method

Technical field

The invention relates to the field of electric power, in particular to a single-phase synchronous generator, a single-phase power supply, an arc suppression system and an arc suppression method.

Background technique

Most domestic 6KV to 35KV distribution networks are neutral point ungrounded systems. According to statistics, more than 70% of the faults in the distribution network system are single-phase ground faults. In the case of a single-phase ground fault, the arc is difficult to extinguish, and it is easy to produce high-frequency overvoltage and power frequency overvoltage, which endanger the normal operation of the system. If the arc is difficult to extinguish for a long time, then a phase-to-phase short-circuit accident may also occur, leading to more serious consequences.

In related technologies, an arc suppression coil is usually connected to the neutral point of the distribution network to compensate the current at the ground fault point and eliminate the arc at the ground fault point. However, in recent years, with the increase in the cableization rate, the capacitive current to the ground of the distribution network system is increasing, and the absolute value of the resistive current, high-frequency current and harmonic current is also increasing. Since the above arc suppression coil can only compensate the power frequency capacitive current flowing through the ground fault point, it is difficult to effectively suppress the arc.

The related technology also adopts the transfer arc suppression technology, that is, the ground fault point is directly metal grounded through the selector switch on the bus side of the distribution network system to transfer the current at the ground fault point and eliminate the arc at the ground fault point. However, in the above arc extinguishing process, due to the inaccurate judgment of the ground fault phase, the different names may be grounded, resulting in a short circuit between the phases, leading to a more serious short circuit accident.

Summary of the invention

In order to solve the above problems, the present invention provides a single-phase synchronous generator, a single-phase power supply, an arc suppression system and an arc suppression method.

According to one aspect of the present invention, there is provided a single-phase synchronous generator, including an inner stator assembly, a rotor assembly, and an outer stator assembly arranged from the inside to the outside, wherein the inner stator assembly includes a first Field winding; the rotor assembly is connected to an external motor through a coupling and rotates with it, so that the first power generation winding inside the rotor assembly generates three-phase alternating current, wherein the three-phase alternating current is rectified and supplied to the rotor A second field winding on the outside of the assembly; and the outer stator assembly includes a second power generating winding for providing a single-phase power output.

Preferably, the rotor assembly includes: a rotor core connected to the external motor through the coupling, the first power generating winding provided on the inner side of the rotor core, and the first power generating winding provided on the outer side of the rotor core. The second field winding and the cage structure winding arranged at the slot position on the outer side of the rotor core.

Preferably, the cage structure winding is composed of a plurality of guide bars, and the number of the guide bars is the same as the number of slots of the rotor core.

Preferably, the cross-sectional area of the guide bar is the same as the winding cross-sectional area of the second power generating winding.

Preferably, the air gap outside the outer stator assembly and the rotor assembly is 1.2 to 1.8 times the rated air gap.

According to another aspect of the present invention, there is provided a single-phase power supply, including a three-phase asynchronous motor and any of the above-mentioned single-phase synchronous generators, wherein the single-phase synchronous generator is connected to the three-phase asynchronous generator through a coupling. The motor is connected and rotates with it.

Preferably, the single-phase synchronous generator and the three-phase asynchronous motor are integrally assembled and formed.

According to another aspect of the present invention, there is provided an arc suppression system, including: a grounding transformer, the first end of which is connected to the power distribution network, and the second end is grounded through a generator unit; and a voltage sensor is connected to the power distribution network. And a measurement and control unit, respectively connected to the voltage sensor and the generator unit, the measurement and control unit determines whether a ground fault occurs in the distribution network according to the voltage of the distribution network fed back by the voltage sensor, and In the case of a ground fault, the measurement and control unit controls the generator unit to adjust the amplitude and angle of the compensation voltage accordingly, wherein the generator unit is any single-phase power supply described above.

According to another aspect of the present invention, there is provided an arc suppression method, which is applied to the above arc suppression system, and includes: a single-phase power supply receives a control command from a measurement and control unit, wherein the control command is used for a ground fault in a power distribution network. In this case, indicating the target amplitude and target angle of the compensation voltage; and the single-phase power supply adjusts its single-phase power output to the target amplitude and the target angle.

Preferably, the single-phase power supply adjusting its single-phase power output to the target amplitude and the target angle includes: according to the target amplitude, the single-phase power supply increases the excitation current of the second excitation winding to Several multiples of the rated excitation current; according to the target angle, the single-phase power supply maintains the enhanced excitation current for a certain time; and when the output of the single-phase power supply is adjusted to the target amplitude and the target angle, The single-phase power supply restores the excitation current to the rated excitation current.

In the embodiment of the present invention, a grounding transformer is provided with a compensation voltage of appropriate phase and amplitude through a single-phase power supply, which can reduce the voltage at the ground fault point and eliminate the arc at the ground fault point.

Description of the drawings

The drawings described here are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Fig. 1 is one of the schematic diagrams of an arc suppression system according to an embodiment of the present invention;

Fig. 2 is a second schematic diagram of an arc suppression system according to an embodiment of the present invention;

Fig. 3 is a third schematic diagram of an arc suppression system according to an embodiment of the present invention;

Figure 4 is a schematic diagram of a single-phase power supply according to an embodiment of the present invention;

Fig. 5 is a schematic diagram of a single-phase synchronous generator according to an embodiment of the present invention;

Figure 6 is a schematic diagram of an inner stator assembly and an outer stator assembly according to an embodiment of the present invention;

Figure 7 is a schematic diagram of a rotor assembly according to an embodiment of the present invention;

Fig. 8 is a flowchart of an arc suppression method according to an embodiment of the present invention;

Fig. 9 is a detailed flowchart of an arc suppression method according to an embodiment of the present invention; and

Fig. 10 is a flowchart of an arc suppression method according to a specific example of the present invention.

Detailed ways

It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other if there is no conflict. Hereinafter, the present invention will be described in detail with reference to the drawings and in conjunction with the embodiments.

The embodiment of the present invention provides an arc suppression system. Fig. 1 is one of the schematic diagrams of an arc suppression system according to an embodiment of the present invention. As shown in Fig. 1, the arc suppression system includes: a grounding transformer 1, the first end of which is connected to the power distribution network, and the second end is through a generator unit 3Ground. The arc suppression system further includes: a voltage sensor 4 connected to the power distribution network; and a measurement and control unit 5 respectively connected to the voltage sensor 4 and the generator unit 3, the measurement and control unit 5 according to the voltage sensor 4 feedback of the distribution The voltage of the power grid determines whether a ground fault occurs in the distribution network, and, in the case of a ground fault, the measurement and control unit 5 controls the generator unit 3 to adjust the amplitude and angle of the compensation voltage accordingly.

In the embodiment of the present invention, the grounding transformer 1 is provided with a compensation voltage of appropriate phase and amplitude through the generator unit 3, which can reduce the voltage at the ground fault point and eliminate the arc at the ground fault point. The generator unit 3 may be a single-phase power source (single-phase synchronous generator), and its specific structure will be described in detail below. Among them, the voltage sensor 4 can be any sensor capable of detecting voltage signals in the related art. Those skilled in the art know that the addition of the voltage sensor 4 is beneficial to more accurately determine whether a ground fault occurs in the distribution network, and in the event of a ground fault, the generator unit 3 provides the grounding transformer 1 with appropriate phase and amplitude. Compensation voltage.

According to the embodiment of the present invention, the arc suppression system further includes: a current sensor 6 connected in series with the generator unit 3 for detecting the current of the generator unit 3; and the measurement and control unit 5 also feedbacks according to the current sensor 6 The current of the generator unit 3 determines whether the ground fault of the distribution network is an instantaneous ground fault or a permanent ground fault. Those skilled in the art know that the addition of the current sensor 6 is beneficial to further determine whether the ground fault of the distribution network is an instantaneous ground fault or a permanent ground fault, so as to further trigger other electronic components according to the ground fault (for example, not shown in the figure). The ground fault selector switch) is opened or closed accordingly.

According to the embodiment of the present invention, the generator unit 3 can be connected in series with the current sensor 6 (see Fig. 1). According to the embodiment of the present invention, the generator unit 3 can also be connected to the grounding transformer 1 through the isolation coil 7 (see FIG. 2). Wherein, the isolation coil 7 includes a first coil and a second coil mutual inductance with the first coil, wherein the first end of the generator unit 3 is connected to the first end of the second coil, and the generator unit 3 The second end is connected to the second end of the second coil.

FIG. 3 is the third schematic diagram of the arc suppression system according to the embodiment of the present invention. As shown in FIG. 3, the arc suppression system further includes a compensation coil 2 connected in series with the generator unit 3. In this embodiment, the compensation coil 2 is further used to provide the grounding transformer 1 with a compensation voltage of appropriate phase and amplitude, which can further reduce the ground fault point voltage and eliminate the ground fault point arc.

The embodiment of the present invention also provides a single-phase power supply. Fig. 4 is a schematic diagram of a single-phase power supply according to an embodiment of the present invention. As shown in Fig. 4, the single-phase power supply includes: a three-phase asynchronous motor M and a single-phase synchronous generator G, wherein the single-phase synchronous generator G is connected The shaft device is connected with the three-phase asynchronous motor M and rotates with it.

In the embodiment of the present invention, the single-phase power output provided by the single-phase power supply is a compensation voltage with adjustable phase and amplitude, which can be applied to any of the above-mentioned arc suppression systems.

It should be noted that although the three-phase asynchronous motor M and the single-phase synchronous generator G described in FIG. 4 are separately formed and connected by a coupling, this is only an embodiment of the present invention. Any implementation that can connect the three-phase asynchronous motor M and the single-phase synchronous generator G, for example, the single-phase synchronous generator and the three-phase asynchronous motor are assembled integrally, should be included in the protection scope of the present invention.

The following describes in detail how to provide a compensation voltage with adjustable phase and amplitude in combination with the structure of the single-phase synchronous generator G.

Fig. 5 is a schematic diagram of a single-phase synchronous generator according to an embodiment of the present invention. As shown in Fig. 5, the single-phase synchronous generator G includes an inner stator assembly, a rotor assembly, and an outer stator assembly arranged from the inside to the outside, wherein the The inner stator assembly includes a first field winding for accessing direct current; the rotor assembly is connected to an external motor through a coupling and rotates with it, so that the first generating winding inside the rotor assembly generates three-phase alternating current, wherein the three The phase alternating current is rectified and provided to the second field winding outside the rotor assembly; and the outer stator assembly includes a second power generation winding for providing a single-phase power output.

In the embodiment of the present invention, since the rotor assembly follows the rotation of the external motor, and at the same time, since the second field winding has an excitation current with adjustable phase and amplitude, the second generator winding can induce the corresponding phase and amplitude adjustable Single-phase power output.

According to an embodiment of the present invention, the rotor assembly includes: a rotor core connected to the external motor through the coupling, the first power generating winding provided on the inner side of the rotor core, and the second generator winding provided on the outer side of the rotor core. The field winding and the cage structure winding arranged at the slot position on the outer side of the rotor core.

In the embodiment of the present invention, considering that one of the shortcomings of the single-phase synchronous generator is the existence of a negative sequence magnetic field, the negative sequence magnetic field will cause the single-phase synchronous generator to vibrate, so the embodiment of the present invention is still in the notch of the rotor core The position is provided with the following cage structure windings in order to eliminate the negative sequence magnetic field as much as possible.

(1) The cage structure winding adopts a fully damped structure, that is, the number of leads composing the cage structure winding is the same as the number of slots in the rotor core.

(2) The conductive bars composing the cage structure winding have a sufficient cross-sectional area, for example, the cross-sectional area is the same as the winding cross-sectional area of the second power generating winding.

(3) The conductive bars composing the cage structure winding are made of low-resistance materials, such as gold, silver or red copper.

According to the embodiment of the present invention, increasing the air gap between the outer stator assembly and the rotor assembly to 1.2 to 1.8 times the rated air gap may also eliminate the negative sequence magnetic field. The reason is that increasing the air gap will significantly reduce the interaction between the negative sequence air gap rotating magnetic field and the positive sequence air gap rotating magnetic field, thereby significantly reducing the negative sequence magnetic field.

It should be noted that, referring to FIG. 5, regardless of the number of windings of the second field winding and the cage structure winding or the number of windings of the second power generating winding, it is only an embodiment of the present invention. In practical applications, any single phase can be realized. The number of other windings output by the power supply should be included in the protection scope of the present invention.

In addition, referring to Figure 4, those skilled in the art should also understand that the single-phase power supply also includes a chopper for chopping the rectified DC power under the control of the controller, so as to adjust it to suit the single-phase power supply. The voltage of the phase synchronous generator. Among them, the rectifier and the chopper can be installed on a three-phase excitation generator and rotate with it. It should be noted that the above-mentioned combination of three-phase excitation generator, rectifier and chopper is only an embodiment of the present invention. In practical applications, any suitable excitation current can be provided to the DC excitation winding of a single-phase synchronous generator. The implementation modes should all be included in the protection scope of the present invention.

At the same time, referring to Figure 4, those skilled in the art should also understand that the single-phase power supply also includes a frequency converter, which is used to adjust the input frequency of an external motor (such as a three-phase asynchronous motor M) under the control of the controller, thereby adjusting its input frequency. Rotating speed. It should be noted that the above-mentioned frequency conversion adjustment is only an embodiment of the present invention. In practical applications, any embodiment capable of adjusting the rotational speed of the three-phase asynchronous motor M should be included in the protection scope of the present invention.

In order to more clearly illustrate the implementation of the above-mentioned single-phase power supply, the present invention also provides a specific example.

(1) Three-phase asynchronous motor M

The motor can choose 380V/200KW variable frequency motor. It can keep rotating according to the corresponding speed under the adjustment of the frequency converter. Moreover, regardless of whether the first power generating winding in the single-phase synchronous generator G generates an excitation current, the variable frequency motor always keeps rotating.

(2) Single-phase synchronous generator G

The single-phase synchronous generator G can be understood as consisting of a three-phase excitation generator and a single-phase synchronous generator body. Among them, the exciter can choose a 220V/4KW three-phase AC generator. For example, taking the Y132 motor as a reference, a generator whose stator is DC excitation and the rotor is a three-phase armature winding. At the same time, the rated value of the DC excitation voltage of the exciter can be 75V, and the excitation current can be 4A, powered by an external power supply, and stabilized and smoothed with a capacitor. And among them, the single-phase synchronous generator body can take the Y355 motor as a reference, adopt a generator whose rotor is DC excitation, and the stator is a single-phase power output. The power output provided by it can achieve voltage 0-1000V and current 0-150A. The transition process is not more than 150ms.

It should be noted that the single-phase synchronous generator G in this example is based on the three-phase excitation generator and the single-phase synchronous generator body. "Special motor structure. This can provide a stable phase and amplitude adjustable compensation voltage applied to any of the above-mentioned arc suppression systems.

Further, the outer stator assembly of the single-phase synchronous generator G can be 72 slots (refer to Fig. 6), adopting a 4-level structure, and each coil is wound with 7-φ1.6mm enameled wire with 5 turns (double layer) Y=15.

Further, the rotor assembly of the single-phase synchronous generator G can be 64 slots (refer to FIG. 7), adopt a 4-level structure, and each coil is wound with 3-φ1.6mm enameled wire with 14 turns (double layer) Y=14.

The embodiment of the present invention provides an arc suppression method. The arc suppression method can be applied to any of the above arc suppression systems. Fig. 8 is a flowchart of an arc suppression method according to an embodiment of the present invention. As shown in Fig. 8, the method includes the following steps S802 to S804.

In step S802, the single-phase power supply receives a control instruction from the measurement and control unit, where the control instruction is used to indicate the target amplitude and target angle of the compensation voltage when a ground fault occurs in the distribution network.

In step S804, the single-phase power supply adjusts its single-phase power output to the target amplitude and the target angle.

Fig. 9 is a detailed flowchart of an arc suppression method according to an embodiment of the present invention. As shown in FIG. 9, step S804 includes the following steps S8042 to S8046.

In step S8042, according to the target amplitude, the single-phase power supply increases the excitation current of the second excitation winding to several multiples of the rated excitation current.

In step S8044, according to the target angle, the single-phase power supply continues the enhanced excitation current for a specific time.

In step S8046, when the output of the single-phase power supply is adjusted to the target amplitude and the target angle, the single-phase power supply restores the excitation current to the rated excitation current.

The embodiment of the present invention adopts strong excitation several times higher than the rated excitation, which can improve the response speed of the single-phase power supply, make it output the compensation current of the target amplitude and target angle faster, reduce the voltage of the ground fault point faster, and eliminate the grounding Arc at the fault point.

In order to more clearly illustrate the implementation of the above arc suppression method, the present invention also provides a specific example.

Fig. 10 is a flowchart of an arc suppression method according to a specific example of the present invention. As shown in FIG. 10, the method includes the following steps S1002 to S1010.

In step S1002, the system runs normally without load.

In step S1004, it is judged whether the system has a single-phase grounding, if yes, proceed to step S1006, otherwise, return to step S1002.

In step S1006, high-strength excitation is used to adjust the excitation current.

In step S1008, it is judged whether the rated excitation is satisfied, if so, continue to step S1010, otherwise, return to step S1006.

In summary, the present invention provides a single-phase power supply, an arc suppression system and an arc suppression method. The arc extinguishing system includes a grounding transformer and a single-phase power supply, wherein a first end of the grounding transformer is connected to a power distribution network, and a second end of the grounding transformer is grounded through the single-phase power supply. The invention provides the grounding transformer with a compensation voltage of suitable phase and amplitude through a single-phase power supply, which can reduce the voltage at the ground fault point and eliminate the arc at the ground fault point.

Obviously, those skilled in the art should understand that the above-mentioned modules or steps of the present invention can be implemented by a general computing device, and they can be concentrated on a single computing device or distributed in a network composed of multiple computing devices. Above, alternatively, they can be implemented with program codes executable by a computing device, so that they can be stored in a storage device to be executed by the computing device, or they can be made into individual integrated circuit modules, or their Multiple modules or steps are made into a single integrated circuit module to achieve. In this way, the present invention is not limited to any specific combination of hardware and software.

The above are only preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

A single-phase synchronous generator is characterized by comprising an inner stator assembly, a rotor assembly and an outer stator assembly arranged from the inside to the outside, wherein:

The inner stator assembly includes a first field winding for connecting direct current;

The rotor assembly is connected to an external motor through a coupling and rotates with it, so that the first power generating winding inside the rotor assembly generates three-phase alternating current, wherein the three-phase alternating current is rectified and supplied to the outside of the rotor assembly The second field winding; and

The outer stator assembly includes a second power generating winding for providing a single-phase power output.
The single-phase synchronous generator according to claim 1, wherein the rotor assembly comprises:

The rotor core connected with the external motor through the coupling,

The first power generating winding arranged inside the rotor core,

The second field winding provided on the outer side of the rotor core, and

A cage-shaped structure winding arranged at the position of the slot on the outer side of the rotor core.
The single-phase synchronous generator according to claim 2, wherein the cage structure winding is composed of a plurality of guide bars, and the number of the guide bars is the same as the number of slots of the rotor core.
The single-phase synchronous generator according to claim 3, wherein the cross-sectional area of the conductive bar is the same as the winding cross-sectional area of the second power generating winding.
The single-phase synchronous generator according to any one of claims 1 to 4, wherein the air gap outside the outer stator assembly and the rotor assembly is 1.2 to 1.8 times the rated air gap.
A single-phase power supply, characterized by comprising a three-phase asynchronous motor and a single-phase synchronous generator according to any one of claims 1 to 5, wherein the single-phase synchronous generator is connected to the single-phase synchronous generator through a coupling The three-phase asynchronous motor is connected and rotates with it.
The single-phase power supply according to claim 6, wherein the single-phase synchronous generator and the three-phase asynchronous motor are integrally assembled and formed.
An arc suppression system, characterized in that it comprises:

A grounding transformer, the first end of which is connected to the power distribution network, and the second end is grounded through the generator unit;

A voltage sensor connected to the power distribution network; and

The measurement and control unit is respectively connected to the voltage sensor and the generator unit. The measurement and control unit determines whether a ground fault occurs in the distribution network according to the voltage of the distribution network fed back by the voltage sensor, and In the event of a ground fault, the measurement and control unit controls the generator unit to adjust the amplitude and angle of the compensation voltage accordingly,

Wherein, the generator unit is the single-phase power supply according to any one of claims 1 to 7.
An arc suppression method applied to the arc suppression system according to claim 8, characterized in that it comprises:

The single-phase power supply receives a control instruction from the measurement and control unit, where the control instruction is used to indicate the target amplitude and target angle of the compensation voltage in the case of a ground fault in the distribution network; and

The single-phase power supply adjusts its single-phase power output to the target amplitude and the target angle.
The arc suppression method according to claim 9, wherein the single-phase power supply adjusting its single-phase power output to the target amplitude and the target angle comprises:

According to the target amplitude, the single-phase power supply increases the excitation current of the second excitation winding to several multiples of the rated excitation current;

According to the target angle, the single-phase power supply maintains the enhanced excitation current for a certain time; and

When the output of the single-phase power supply is adjusted to the target amplitude and the target angle, the single-phase power supply restores the excitation current to the rated excitation current.