CN215835340U

CN215835340U - Small electronic excitation device

Info

Publication number: CN215835340U
Application number: CN202121336065.5U
Authority: CN
Inventors: 尹宏尚
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-06-16
Filing date: 2021-06-16
Publication date: 2022-02-15
Anticipated expiration: 2031-06-16

Abstract

The utility model discloses a small-sized electronic excitation device, which comprises a power frequency rectifier, an inverter, an intermediate frequency transformer and an intermediate frequency filter which are connected in sequence, wherein the power frequency rectifier is used for rectifying three-phase alternating current into direct current; the inverter is used for inverting the direct current into medium-frequency alternating current; the intermediate frequency transformer is an amorphous pure copper core transformer; the medium-frequency filter is used for respectively rectifying and filtering the low-voltage alternating current output by the medium-frequency transformer and transmitting the excitation voltage and the excitation current to the excitation coil of the generator. The device can reduce equipment failure rate and hardware cost, reduces the volume and the energy consumption of equipment simultaneously, and the wiring operation is simple.

Description

Small electronic excitation device

Technical Field

The utility model belongs to the technical field of power electronics, and particularly relates to a small electronic excitation device suitable for a synchronous generator.

Background

In the prior art, an excitation device of a synchronous generator adopts an old traditional combined structure of a silicon controlled rectifier and a microcomputer excitation controller, however, in actual operation work, operation and maintenance personnel find that the excitation system is high in energy consumption, large in size, complex in structure, high in failure rate and high in maintenance cost, the excitation controller is often damaged due to the failure of the silicon controlled rectifier, the price for replacing the complete equipment is generally over ten thousand yuan, and in addition, the equipment is large in size and complex in wiring and is not suitable for being applied to a small power station scene.

Therefore, in view of the above deficiencies in the prior art, there is a need for a small electronic excitation device, which aims to reduce the failure rate and maintenance cost of the equipment, and reduce the volume and energy consumption of the equipment.

SUMMERY OF THE UTILITY MODEL

Technical problem to be solved

Based on the technical scheme, the small electronic excitation device is provided, the failure rate and the maintenance cost of equipment can be reduced, the size and the energy consumption of the equipment are reduced, and the wiring operation of the excitation device is simple.

(II) technical scheme

In order to solve the technical problem, the utility model provides a small-sized electronic excitation device, which comprises a power frequency rectifier, an inverter, an intermediate frequency transformer and an intermediate frequency filter which are sequentially connected, wherein the power frequency rectifier is used for rectifying three-phase alternating current into direct current; the inverter is used for inverting the direct current into medium-frequency alternating current; the intermediate frequency transformer is an amorphous pure copper core transformer; the intermediate frequency filter is used for respectively rectifying and filtering the low-voltage alternating current output by the intermediate frequency transformer and transmitting the excitation voltage and the excitation current to the excitation coil of the generator.

Furthermore, the inverter comprises two switching tubes which are alternately conducted with each other and are connected in series.

Further, the switch tube is an IGBT tube or a fast thyristor.

Further, the output range of the exciting current is 0-250A, and the output range of the exciting voltage is 0-70V.

Further, the intermediate frequency filter comprises a secondary side rectifying circuit and a filter circuit.

Further, the output end of the intermediate frequency filter is also connected with a voltmeter and an ammeter.

Furthermore, the small electronic excitation device also comprises a current-limiting protection circuit and a voltage-limiting protection circuit.

(III) advantageous effects

Compared with the prior art, the small electronic excitation device has the advantages that:

1) the electronic excitation device adopts the rectification and inversion technology, and the inverter changes the intermediate frequency transformer T by utilizing the alternate conduction of a fast thyristor or an IGBT₂The flow path current direction of the transformer converts low-frequency direct current into intermediate-frequency alternating current, the working frequency range of the low-frequency direct current is 0.5 KHZ-4 KHZ, and the low-frequency direct current is in direct proportion to the output power of the exciter (namely, the higher the working frequency of the inverter is, the higher the output power of the exciter is, and vice versa), and a strong direct current can be generated by the existing PWM modulation technology so as to supply the generator for excitation. According to the utility model, through the organic combination of the power frequency rectifier, the inverter with the frequency conversion function, the intermediate frequency transformer with the pure copper core amorphous transformer and the intermediate frequency filter with the secondary side rectification, the size of the whole electronic excitation device is greatly reduced, the dynamic characteristics are better and more stable (the excitation voltage range is 0-70V, and the excitation current range is 0-250A), and finally the energy consumption is reduced by more than 30%.

2) Compared with the original large-scale silicon controlled rectifier and large-scale transformer, the electronic excitation device adopts the amorphous transformer and the new generation of IGBT or fast thyristor, so that the volume of the whole excitation equipment is greatly reduced, and the whole equipment can be portable and movable and is convenient to install.

3) In addition, the input and output wiring of the electronic excitation device is simple, the electronic excitation device is easy to adjust and convenient to operate and maintain, a voltage-limiting and current-limiting protection module is further integrated in the device to protect each power electronic device, the requirement of an excitation control system of a synchronous generator below 1000KW can be met, the electronic excitation device has strong anti-interference performance, and the electronic excitation device is an ideal excitation device of a small generator set.

Drawings

The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the utility model in any way, and in which:

FIG. 1 is a block diagram of a compact electronic exciter of the present invention;

fig. 2 is a circuit diagram of a small-sized electronic excitation device according to an embodiment of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; the two elements may be mechanically or electrically connected, directly or indirectly connected through an intermediate medium, or may be connected through communication between the two elements, or may be "drive-connected", i.e., power-connected through various suitable means such as belt drive, gear drive, or sprocket drive. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The utility model will be further described with reference to fig. 1-2.

In order to solve the problems of miniaturization and energy conservation of an excitation device, the utility model provides a technical scheme that: as shown in fig. 1, the small electronic excitation device includes a power frequency rectifier, an inverter, an intermediate frequency transformer, and an intermediate frequency filter, which are connected in sequence, wherein the power frequency rectifier is used for rectifying three-phase alternating current into direct current; the inverter is used for converting the direct current into intermediate frequency alternating current; the intermediate frequency transformer is an amorphous pure copper core transformer (namely a pure copper amorphous transformer), the amorphous transformer with a pure copper core belongs to an energy-saving and environment-friendly transformer, the no-load loss and the load loss are low (more than 30% of electricity is saved), the internal working voltage of hundreds of volts can be converted into the low voltage of dozens of volts, and the safety coefficient is high; the medium-frequency filter is used for sequentially rectifying and filtering the low-voltage alternating current output by the medium-frequency transformer and outputting ideal 10-70V excitation voltage and excitation current to a generator excitation coil.

Specifically, the method comprises the following steps: the inverter comprises two parallel switching tubes which are alternately conducted with each other, the switching tubes of the single bridge arm can complete the DC/AC conversion of frequency conversion through the control of the PWM controller, and the required output power can be adjusted; the switch tube is preferably an IGBT tube or a fast thyristor; the intermediate frequency filter comprises a secondary rectifying circuit and a filter circuit, and the output end of the intermediate frequency filter is also provided with a voltmeter and an ammeter so as to measure and display the output excitation voltage and current in real time.

In addition, the PWM controller performing the inverter control according to the current sampling and the current setting may adopt an excitation control technique in the related art, and the excitation control portion is not an improvement portion of the present invention, that is, the excitation control method belongs to the related art control method.

On the basis of fig. 1, the present invention designs a specific circuit diagram of an electronic excitation device, as shown in fig. 2, as one embodiment, a main circuit of the electronic excitation device includes a current-limiting and voltage-limiting circuit, a primary side rectification circuit, a filter circuit, a voltage-limiting circuit board PCB1, an electrical control board PCB2, a protection circuit board PCB3, an inverter, and a secondary side rectification filter circuit.

The following briefly describes the individual circuits:

1. the current and voltage limiting circuit is composed of an automatic air switch QS₁A varistor R₁Capacitor C₂Winding resistor R₂Composition, QS₁The automatic air switch with a compound tripping mechanism is characterized in that when an excitation device is overloaded for a long time, the thermal tripping mechanism acts to disconnect the power supply of the device, and if the excitation device fails or is strongly interfered by the outside, the primary side of a main loop of the excitation device generates a current larger than 300A, QS (quality of service) is realized₁The electromagnetic tripping mechanism can act within 10ms to cut off the power supply of the machine, and the piezoresistor R₁Capacitor C₂The device is used for absorbing spike voltage from a power grid so as to protect semiconductor devices such as a fast thyristor and the like. When the exciter fails or meets external strong interference, the 'inversion failure' (or 'through', namely VTH) is caused₃、VTH₄And simultaneously conducting), when the primary side of the main loop of the exciter has large current, R is₂The maximum value of the current will be no more than 400A.

2. A primary side rectifying and filtering circuit as a power frequency rectifier consisting of QL₁、C₄～C₇、 L₁、L₂Composed of equal components, QL₁The three-phase rectifier bridge has the function of converting three-phase alternating current into direct current with smaller ripples. C₄～C₇、L₁、L₂The elements mainly functioning as intermediate-frequency filters, C₄～C₇The medium-frequency electrolytic capacitor is specially used in the inverter excitation device.

3. Voltage limiting circuit board PCB₁For limiting VTH of fast thyristor₃、VTH₄、C₃、 C₈～C₁₁When the voltage at two ends of the component is 250V higher than the point A, TH₁On, when the potential at the point C is 250V higher than that at the point B, VTH₂And conducting.

4. Inverter composed of fast thyristors VTH₃、VTH₄And a commutation capacitor C₃、C₈～ C₁₁Amorphous transformer T₂When the inverter works normally, VTH is formed by equal components₃、 VTH₄Are conducted in turn to change the flow path T₂The inverter of the electronic excitation device is a frequency conversion system, the working frequency of the inverter is 0.5 KHZ-4 KHZ, and is in direct proportion to the output power of the exciter, namely, the higher the working frequency of the inverter is, the higher the output power of the exciter is, and vice versa.

5. As a secondary side rectifying and filtering circuit of the intermediate frequency filter, a fast recovery rectifying tube VD₃、VD₄Reactor L₃、L₄Intermediate frequency electrolytic capacitor C₁₇～C₂₀The voltage is reduced by an intermediate frequency transformer of an amorphous transformerThe later intermediate frequency alternating current is supplied by a diode VD₃、VD₂Rectified and converted into direct current and then passes through a reactor L₃、L₄Electrolytic capacitor C₁₇～C₂₀After being filtered, the elements are converted into direct current suitable for the excitation coil of the generator.

The electric signal of the electronic excitation device is converted as follows: firstly, the input Sanxiang alternating current 380V/50HZ is rectified at power frequency, inverted by an inverter containing a fast thyristor or IGBT, then stepped down by an intermediate frequency transformer, rectified and filtered to output direct current, and the output direct current is sampled by a shunt and then is compared with an excitation current set value (namely a variable resistor RP) of a generator ₂Where) for comparison, the electrical control board PCB2 controls the fast thyristor or IGBT for inversion control by means of PWM.

In the utility model, a three-phase input binding post and two output excitation binding posts are arranged at the back of the excitation device, a cooling fan is arranged, a digital display screen for excitation current and excitation voltage is arranged on a front panel to display current and voltage data in the ranges of 0-270A and 0-70V, and a manual adjusting knob for current set values and an operation panel for an air switch are arranged.

Compared with the prior art, the specially-made small-sized electronic excitation device can reduce the failure rate and the maintenance cost of equipment, simultaneously reduce the volume and the energy consumption of the equipment, and has simple wiring operation, and the cost of the whole set of equipment can be reduced to below 4 thousand yuan.

Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the utility model, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A small-sized electronic excitation device is characterized by comprising a power frequency rectifier, an inverter, an intermediate frequency transformer and an intermediate frequency filter which are sequentially connected, wherein the power frequency rectifier is used for rectifying three-phase alternating current into direct current; the inverter is used for inverting the direct current into medium-frequency alternating current; the intermediate frequency transformer is an amorphous pure copper core transformer; the medium-frequency filter is used for respectively rectifying and filtering the low-voltage alternating current output by the medium-frequency transformer and transmitting the excitation voltage and the excitation current to the excitation coil of the generator.

2. The miniature electronic excitation device of claim 1, wherein the inverter comprises two switching tubes alternately conducting with each other and connected in series.

3. The miniature electronic excitation device of claim 2, wherein the switching tube is an IGBT tube or a fast thyristor.

4. The small-sized electronic excitation device according to any one of claims 1 to 3, wherein the output range of the excitation current is 0 to 250A, and the output range of the excitation voltage is 0 to 70V.

5. The miniature electronic excitation device according to any one of claims 1 to 3, wherein the intermediate frequency filter comprises a secondary rectification circuit and a filter circuit.

6. The miniature electronic excitation device according to any one of claims 1 to 3, wherein a voltmeter and an ammeter are further connected to an output end of the intermediate frequency filter.

7. The miniature electronic excitation device of any one of claims 1 to 3, further comprising a current limiting circuit and a voltage limiting circuit.