CN221283030U

CN221283030U - Power supply circuit in static reactive compensation equipment

Info

Publication number: CN221283030U
Application number: CN202322968962.3U
Authority: CN
Inventors: 石娟; 孙际哲
Original assignee: Air Force Engineering University of PLA
Current assignee: Air Force Engineering University of PLA
Priority date: 2023-11-02
Filing date: 2023-11-02
Publication date: 2024-07-05
Anticipated expiration: 2033-11-02

Abstract

The utility model discloses a power supply circuit in static reactive compensation equipment, which comprises a power supply module, a first voltage conversion circuit and a second voltage conversion circuit, wherein the first voltage conversion circuit is connected with the power supply module; the second voltage conversion circuit is connected with the first voltage conversion circuit; the positive reference level conversion circuit is connected with the power supply module; the negative reference level conversion circuit is connected with the power supply module; and the reference voltage conversion circuit is connected with the positive reference level conversion circuit. By constructing the power supply circuit by utilizing the discrete devices, the power supply circuit not only can stably and reliably provide power supplies with different voltage levels and precision for the control acquisition unit of the SVG equipment, thereby ensuring the safe and stable operation of the whole SVG equipment, but also has the characteristics of economy, reliability, stable performance, small volume and low price.

Description

Power supply circuit in static reactive compensation equipment

Technical Field

The utility model relates to the technical field of control of power electronic systems, in particular to a power supply circuit in static reactive compensation equipment.

Background

Power electronics technology has evolved rapidly and has found great use in power systems, where Static Var Generators (SVG) are used primarily to regulate and control reactive power in power systems to improve system stability and power quality. SVG is commonly used in transmission and distribution links of power systems. The reactive power compensation system can improve the stability, reliability and power quality of the power system, reduce energy consumption and line loss, adapt to the dynamic demand of the power system on reactive power, and reduce the dependence on traditional reactive power compensation equipment (such as a compensation capacitor). In summary, SVG plays an important role in power systems, providing an effective solution for the operation and optimization of power systems.

The control portion of an SVG device typically requires a stable and reliable power supply circuit to ensure proper operation and accurate control. For this purpose, a suitable chip is selected in the power supply circuit, and a suitable filter capacitor and a suitable filter inductance are added to reduce the influence of power supply ripple and high-frequency noise on the control circuit, which is helpful to provide cleaner and stable power supply voltage for the control part. In actual use, however, SVG devices often cause damage and anomalies to the entire device due to instability of the power supply module.

Therefore, it is important for SVG devices to provide a stable, reliable, safe power supply. The power supply of the prior SVG device generally adopts an integrated power module, but the integrated power module has the following defects: bulky, expensive, and the output power cannot be modified according to actual project requirements.

Disclosure of utility model

The utility model provides a power supply circuit in static reactive compensation equipment, which is based on discrete device design and can solve the problems of single power supply voltage, large volume, high price and the like of the existing integrated power supply module.

A power supply circuit in a static var compensation apparatus for providing power to a control acquisition unit of the static var compensation apparatus, comprising:

the power supply module is used for outputting a positive power supply and a negative power supply of a first voltage value;

The first voltage conversion circuit is connected with the power supply module to convert a positive power supply with a first voltage value into a first working power supply with a second voltage value for output;

the second voltage conversion circuit is connected with the first voltage conversion circuit to convert a first working power supply with a second voltage value into a second working power supply with a third voltage value for output;

The positive reference level conversion circuit is connected with the power supply module to convert a positive power supply with a first voltage value into a positive reference level output with a fourth voltage value;

The negative reference level conversion circuit is connected with the power supply module to convert a positive power supply with a first voltage value into a negative reference level output with a fourth voltage value;

the third voltage conversion circuit is connected with the power supply module to convert the positive power supply with the first voltage value into a third working power supply output with a fifth voltage value;

And the reference voltage conversion circuit is connected with the third voltage conversion circuit to convert the positive reference level of the fifth voltage value into the reference power supply output of the sixth voltage value.

Furthermore, the power module adopts an integrated module type Mingwei power supply with the model of SDR15V, a protection diode is connected in series on the positive electrode of the power module, the cathode of the protection diode is connected with one section of a pull-up resistor R1, the other end of the pull-up resistor R1 outputs the positive power supply, and a capacitor C6 and a capacitor C7 which are connected in parallel are connected between the other end of the pull-up resistor R1 and the grounding end.

Further, the first voltage conversion circuit and the second voltage conversion circuit are connected through a filter circuit, and the filter circuit is composed of an inductor L2 and a capacitor C14.

Further, the first voltage conversion circuit includes a voltage conversion chip U12, an inductor L1, a resistor R2, and a resistor R3, where a voltage input end of the voltage conversion chip U12 is connected to an output end of the positive power supply, a voltage output end of the voltage conversion chip U12 is connected to one end of the inductor L2 through the inductor L1, the other end of the inductor L2 outputs the first working power supply, a common end between the inductor L1 and the inductor L2 is sequentially connected in series with the resistor R2 and the resistor R3 to be grounded, and a common end between the resistor R2 and the resistor R3 is connected to a feedback signal input end of the voltage conversion chip U12.

Further, a freewheeling diode VD4 is reversely connected between the common terminal between the voltage output terminal of the voltage conversion chip U12 and the inductor L1 and the ground terminal, and a capacitor C12 and a capacitor C15, which are arranged in parallel, are also connected between the common terminal between the inductor L1 and the inductor L2 and the ground terminal.

Further, the second voltage conversion circuit includes an LDO voltage stabilizing chip D2, a voltage input end of the LDO voltage stabilizing chip D2 is connected to an output end of the first working power supply, a voltage output end of the LDO voltage stabilizing chip outputs the second working power supply, a capacitor C8, a capacitor C9 and a capacitor C10 are further connected between the voltage output end and a ground end of the LDO voltage stabilizing chip, and a diode VD1 is reversely connected between the voltage output end and the voltage input end of the LDO voltage stabilizing chip.

Further, the positive reference level conversion circuit includes a voltage regulator N3, an anode of the voltage regulator N3 is grounded, a cathode of the voltage regulator N3 outputs the positive reference level, the cathode of the voltage regulator N3 is connected with an output end of the positive power supply after passing through a resistor R7, a resistor R8, a resistor R9 and a resistor R10 which are connected in parallel, a reference electrode of the voltage regulator N3 is connected with a cathode of the voltage regulator N20 after being connected in series, a reference electrode of the voltage regulator N3 is grounded through a resistor R24, and a capacitor C25 is connected between the anode and the cathode of the voltage regulator N3.

Further, the negative reference level conversion circuit includes a voltage regulator N4, an anode of the voltage regulator N4 is connected with a negative power supply, a cathode of the voltage regulator N4 outputs the negative reference level, the cathode of the voltage regulator N4 is grounded after being connected with a resistor R11, a resistor R12, a resistor R13 and a resistor R14 in parallel, a reference electrode of the voltage regulator N4 is connected with a cathode of the voltage regulator N4 after being connected with a resistor R21 in series, a reference electrode of the voltage regulator N3 is connected with the negative power supply through a resistor R25, and a capacitor C26 is connected between the anode and the cathode of the voltage regulator N3.

Further, the reference voltage conversion circuit includes a reference voltage chip U1, an input end of the reference voltage chip U1 is connected with the resistor R16 and an output end of the third voltage conversion circuit through a parallel resistor R15, an input end of the reference voltage chip U1 is connected with a sleep control end, an output end of the reference voltage chip U1 outputs the reference power supply, an input end of the reference voltage chip U1 is connected with a ground end through a parallel capacitor C22 and a parallel capacitor C23, and an output end of the reference voltage chip U1 is connected with the ground end through a parallel capacitor C24 and a parallel capacitor C21.

Further, the first voltage value is 15V, the second voltage value is 3.3V, the third voltage value is 1.8V, the fourth voltage value and the fifth voltage value are 5V, and the sixth voltage value is 3V.

The beneficial effects are that:

1. By constructing the power supply circuit by utilizing the discrete devices, the power supply with different voltage levels and precision can be stably and reliably provided for the control acquisition unit of the SVG equipment, so that the safe and stable operation of the whole SVG equipment is ensured.

2. The integrated power module has the characteristics of economy, reliability, stable performance, small volume and low price, can be customized according to actual project requirements, has higher flexibility and reliability, and effectively overcomes the defects of large volume, high price and incapability of modifying an output power supply according to the actual project requirements of the existing integrated power module.

Drawings

FIG. 1 is a schematic diagram of a SVG apparatus;

FIG. 2 is a schematic block diagram of the present utility model;

FIG. 3 is a schematic circuit diagram of a first voltage converting circuit and a second voltage converting circuit;

FIG. 4 is a schematic circuit diagram of a positive reference level shifter circuit;

FIG. 5 is a schematic circuit diagram of a negative reference level shift circuit;

FIG. 6 is a schematic circuit diagram of a third voltage conversion circuit;

fig. 7 is a schematic circuit diagram of a reference voltage converting circuit.

Detailed Description

The utility model is further described below with reference to examples and figures.

As shown in fig. 1, the static var compensation (SVG) device is composed of a power supply circuit, a control acquisition unit and an inversion rectification unit, wherein the power supply circuit is a part of the circuit of the whole SVG device, and the control acquisition unit needs voltages with different voltage levels and different precision. Therefore, the stability and reliability of the power supply circuit are the basis of safe and stable operation of the whole SVG equipment.

The control acquisition units of the SVG device require 3.3V, 1.8V, high precision reference voltages Vref +/-5V and 3V, respectively. The voltage class needs are many, and ordinary integrated power module can't satisfy the demand. The present embodiment thus employs discrete devices to achieve each of the different levels of voltage.

As shown in fig. 2, the power supply circuit is composed of 7 parts, namely:

A reference voltage conversion circuit connected to the third voltage conversion circuit to convert a positive reference level of a fifth voltage value to a reference power supply output of a sixth voltage value;

The first voltage value is 15V, the second voltage value is 3.3V, the third voltage value is 1.8V, the fourth voltage value and the fifth voltage value are 5V, and the sixth voltage value is 3V.

The outputs of the circuits are respectively connected with the control acquisition unit to realize the power supply of the whole control acquisition unit and the overload and overheat protection of the whole power supply circuit so as to ensure the safe and reliable operation of the whole reactive compensation equipment. The power supply circuit is the basis of the operation of the whole equipment, and has large ripple or incomplete protection, and even other circuits of the equipment are advanced, the power supply circuit is unstable, so that the power electronic equipment operates stably and reliably on the premise that: the power supply circuit of the system is stable and reliable.

Referring to fig. 3, the power module adopts an integrated module type Mingwei power supply with the model of SDR15V, a protection diode is connected in series on the positive electrode of the power module, the cathode of the protection diode is connected with one section of a pull-up resistor R1, the other end of the pull-up resistor R1 outputs a positive power supply, and a capacitor C6 and a capacitor C7 which are connected in parallel are connected between the other end of the pull-up resistor R1 and the grounding end.

As can be further seen from fig. 3, the first voltage conversion circuit and the second voltage conversion circuit are connected through a filter circuit, and the filter circuit is formed by an inductor L2 and a capacitor C14, specifically:

The first voltage conversion circuit comprises a voltage conversion chip U12, an inductor L1, a resistor R2 and a resistor R3, wherein the voltage input end of the voltage conversion chip U12 is connected with the output end of a positive power supply, the voltage output end of the voltage conversion chip U12 is connected with one end of the inductor L2 through the inductor L1, the other end of the inductor L2 outputs the first working power supply, a common end between the inductor L1 and the inductor L2 is sequentially connected with the resistor R2 and the resistor R3 in series and grounded, the common end between the resistor R2 and the resistor R3 is connected with the feedback signal input end of the voltage conversion chip U12, a follow current diode VD4 is reversely connected between the common end between the voltage output end of the voltage conversion chip U12 and the inductor L1 and the ground end, and a capacitor C12 and a capacitor C15 which are arranged in parallel are also connected between the common end between the inductor L1 and the inductor L2;

The second voltage conversion circuit comprises an LDO voltage stabilizing chip D2, the voltage input end of the LDO voltage stabilizing chip D2 is connected with the output end of the first working power supply, the voltage output end of the LDO voltage stabilizing chip outputs the second working power supply, a capacitor C8, a capacitor C9 and a capacitor C10 are further connected between the voltage output end of the LDO voltage stabilizing chip and the grounding end, and a diode VD1 is reversely connected between the voltage output end of the LDO voltage stabilizing chip and the voltage input end of the LDO voltage stabilizing chip.

In this example, the voltage conversion chip U12 is an L5973-D chip of an intentional semiconductor, L5973-D is a buck monolithic switching power regulator chip, the switching current is greater than 3A, 2.5A dc current can be provided to the load, when the output current is greater than 3.5A, overcurrent protection can be performed, the input voltage is from 4V to 35V, the output voltage can be set to 1.235V to 35V, the reference voltage is 3.3V/(±2%) LDO operation, the duty ratio is 100%, the internal fixed frequency is 250kHz, the zero load current operation and the thermal shutdown characteristics are provided. When the temperature reaches 85 DEG, the output of the protection cut-off later stage can be automatically started in the chip when the temperature reaches the protection threshold value of the U12-L5973-D chip, and meanwhile, in order to consider the heat dissipation of the chip, a heat disc with the thickness of 2.3mm and 3.01mm is arranged at the bottom of the L5973-D chip, so that the heat disc is also reserved on a PCB in the PCB design of the scheme. In some designs, the designer simply connects the heat dissipation pad of the LDO to the GND network of the PCB surface without punching holes in the pad, which is actually not a real heat dissipation goal. Therefore, the heat dissipation pad of the chip has the effect of not grounding, but increasing the heat dissipation channel of the device and the copper foil (such as GND plane) with large area of the inner layer, and the inner layer plane does not have the heat dissipation pad. Therefore, a scheme of heat dissipation of the hot plate is adopted at the bottom of the L5973-D chip for heat dissipation.

The U12 chip is a buck power chip and is used for completing the voltage conversion from +15V to 3.3V. The diode VD2 connected in series with 15V plays a role in reverse connection prevention protection, the C6 and the C7 play a role in filtering noise waves on the power input side of the chip, and the C15 and the C12 play a role in filtering noise waves on the power output side of the chip. Meanwhile, C12, L2 and C15 complete pi filtering, L1 is buck inductance, R2 and R3 are feedback resistors, C4, C13, C16, C17 and resistor R6 are compensation networks to stabilize buck loops, and VD4 is a freewheeling diode.

The above power supply circuit is a typical buck circuit, the amplitude of the output voltage is determined by feedback resistors R2 and R3, and the calculation formula is as follows:

Where VFB is 1.23V (depending on DATASHEET of the chip), R2 is 4.7kΩ, and R3 is 2.7kΩ.

As calculated, the switching power supply output voltage Vout was 3.37V. In order to ensure the quality of the buck power supply input voltage and the buck power supply output voltage, the scheme is provided with filter capacitors of 0.1uF and 10uF at the input and output. The main function of the circuit capacitor is to provide a low-impedance path for the alternating current signal, namely a bypass capacitor; if the effect of the alternating current signal on the power supply is reduced mainly for increasing the alternating current coupling between the power supply and the ground, the decoupling capacitor can be called; if used in a filter circuit, may also be referred to as a filter capacitor.

The equivalent model of the capacitor is an inductor L _s, a resistor R and a capacitor C are connected in series, the inductor L is the lead wire of the capacitor, the resistor R represents the active power loss of the capacitor, and the capacitor C is a theoretical capacitance value.

When the frequency is appropriate, a series LC series resonance can occur, where the condition of the series resonance is wl=1/WC, w=2 pi×f, and f=1/(2pi×lc) is obtained. The reactance at the center frequency of the series LC circuit is at a minimum represented by a pure resistance, so the center frequency has a filtering effect. The capacitance is capacitive below the resonance frequency and the capacitance is inductive above the resonance frequency. Typically large capacitors filter low frequency waves and small capacitors filter high frequency waves. If the capacitor filters to ground, the rejection of interference is greatly compromised when the frequency exceeds the SFR, so a smaller capacitor is required in parallel to ground. The reason is that the small capacitance, the large SFR value, provides a path to ground for high frequency signals. The following principle is therefore followed when selecting the capacitance: the capacitor filters to the ground, a smaller capacitor is required to be connected in parallel to the ground, and a ground path is provided for high-frequency signals; the capacitor pair ground in the power supply filtering is as close to ground as possible; the two capacitors, one larger and one smaller, are connected in parallel, and are generally required to be different by more than two orders of magnitude, so as to obtain a larger filtering frequency band.

The chip D2 is an LDO voltage stabilizing chip, the type of the chip D2 can be PW6566, the main function of the chip D2 is to convert 3.3V into 1.8V, and the input and output sides of the LDO voltage stabilizing chip are respectively provided with a filter capacitor of 10uF and 0.1 uF. In the circuit, a reverse diode VD1 is connected in parallel to the input and output sides of the LDO voltage stabilizing chip, and the diode is used for protecting the LDO voltage stabilizing chip from being damaged as known by the internal structure of the LDO voltage stabilizing chip.

In addition to the above several types of voltages, 15V also generates reference voltages of 5V and 3V. The reference voltage of +/-5V is mainly generated for the comparison circuit, and 3V is the sampling voltage superposition direct current bias of the operational amplifier. The method comprises the following steps:

Referring to fig. 4, the positive reference level conversion circuit includes a voltage regulator N3, an anode of the voltage regulator N3 is grounded, a cathode of the voltage regulator N3 outputs the positive reference level, the cathode of the voltage regulator N3 is further connected with an output end of the positive power supply through a resistor R7, a resistor R8, a resistor R9 and a resistor R10 which are connected in parallel, a reference electrode of the voltage regulator N3 is connected with a cathode of the voltage regulator N20 in series, a reference electrode of the voltage regulator N3 is further grounded through a resistor R24, and a capacitor C25 is connected between the anode and the cathode of the voltage regulator N3.

Referring to fig. 5, the negative reference level conversion circuit includes a voltage regulator N4, an anode of the voltage regulator N4 is connected with a negative power supply, a cathode of the voltage regulator N4 outputs the negative reference level, the cathode of the voltage regulator N4 is further grounded after passing through a resistor R11, a resistor R12, a resistor R13 and a resistor R14 which are connected in parallel, a reference electrode of the voltage regulator N4 is connected with a cathode of the voltage regulator N4 after being connected with a resistor R21 in series, a reference electrode of the voltage regulator N3 is further connected with the negative power supply through a resistor R25, and a capacitor C26 is connected between the anode and the cathode of the voltage regulator N3.

As can be seen from fig. 4 and fig. 5, the positive reference level converting circuit and the negative reference level converting circuit are implemented by a voltage stabilizer N3 and a voltage stabilizer N4. In the design, TL431 is used to generate the reference voltages, wherein R7, R8, R9, R10 and R11, R12, R13, R14 provide cathode working current for TL431, and R20 and R24, R21 and R25 generate ±5v reference voltages for voltage dividing resistors.

For the TL431 chip, the expression of the output voltage is:

In order to generate the reference voltage Vref+ of +5V, the resistances of R20 and R24 must be the same, which is achieved by using 4.7kΩ in the present design. Similarly, to generate a reference voltage Vref-, of about-5V, R21 and R25 are 4.7kΩ and 1.5kΩ, respectively.

Referring to fig. 6, the third voltage conversion circuit includes a buck chip N1, where the chip N1 is a voltage stabilizing chip of model L7805, and is mainly used to generate an output voltage of 5V for the reference voltage conversion circuit, and the input voltage of N1 is a filtered "pure" positive power supply of +15v.

Referring to fig. 7, the reference voltage conversion circuit includes a reference voltage chip U1, an input end of the reference voltage chip U1 is connected with a resistor R16 and an output end of the third voltage conversion circuit through a parallel resistor R15, an input end of the reference voltage chip U1 is connected with a sleep control end, an output end of the reference voltage chip U1 outputs the reference power, an input end of the reference voltage chip U1 is connected with a ground end through a parallel capacitor C22 and a parallel capacitor C23, and an output end of the reference voltage chip U1 is connected with the ground end through a parallel capacitor C24 and a parallel capacitor C21.

In this example, the reference voltage chip U1 selects REF193, and mainly functions to generate a working voltage required for dc bias of the op-amp, with an amplitude of 3V. Wherein, C22, C23 are input capacitance, C21, C24 are output capacitance, the 3 foot of REF193 is sleep control end, when the level of 3 foot is greater than 2.4V, normally work, when the level is low, it is sleep mode. If there is no special requirement for this pin, 3 pins need to be connected to Vin.

Working principle:

The embodiment is a power supply circuit based on a discrete device, wherein a positive power supply and a negative power supply of +/-15V output by a power supply module are converted into a first working power supply of 3.3V through a buck chip U12 in a first voltage conversion circuit, and meanwhile, the first working power supply of 3.3V is converted into a second working power supply of 1.8V through an LDO chip D2; in addition, the +/-15V voltage output by the power supply module is converted into +/-5V reference level by a voltage stabilizer N3 in the positive reference level conversion circuit and a voltage stabilizer N4 in the negative reference level conversion circuit and is supplied to a comparator in the control acquisition unit, a first working power supply of 3.3V is used for supplying power to a DSP, a CPLD and a CAN communication chip in the control acquisition unit after being filtered and isolated by magnetic beads, 1.8V is used for supplying power to a DSP core in the control acquisition unit, a positive power supply of +/-15V is used for supplying power to an operational amplifier and the comparator, a third voltage conversion circuit is used for converting the positive power supply of 15V into a third working power supply of 5V to supply power to the reference voltage conversion circuit, and the reference power supply of 5V converted into 3V is used for supplying the working voltage required by the operational amplifier when the reference power supply is used for providing direct current bias.

Therefore, the power supply circuit of the embodiment can stably and reliably provide power supplies with different voltage levels and precision for the control acquisition unit of the SVG equipment, so that the safe and stable operation of the whole SVG equipment is ensured, the characteristics of economy, reliability, stable performance, small size and low price are also realized, the customized design can be performed according to actual project requirements, the flexibility and the reliability are high, and the defects that the size is large, the price is high, and the output power supply cannot be modified according to the actual project requirements in the existing integrated power supply module are effectively overcome.

Finally, it should be noted that the above description is only a preferred embodiment of the present utility model, and that many similar changes can be made by those skilled in the art without departing from the spirit and scope of the utility model as defined in the appended claims.

Claims

1. A power supply circuit in a static var compensation device for providing power to a control acquisition unit of the static var compensation device, comprising:

2. The power supply circuit in the static var compensation device according to claim 1, wherein the power supply module adopts an integrated module type Mingwei power supply with the model of SDR15V, a protection diode is connected in series on the positive electrode of the power supply module, the cathode of the protection diode is connected with one section of a pull-up resistor R1, the positive power supply is output by the other end of the pull-up resistor R1, and a capacitor C6 and a capacitor C7 which are connected in parallel are connected between the other end of the pull-up resistor R1 and a grounding end.

3. A power supply circuit in a static var compensation apparatus according to claim 1, characterized in that the first voltage conversion circuit and the second voltage conversion circuit are connected by a filter circuit, which is formed by an inductance L2 and a capacitance C14.

4. A power supply circuit in a static var compensation device according to claim 3, wherein the first voltage conversion circuit comprises a voltage conversion chip U12, an inductor L1, a resistor R2 and a resistor R3, a voltage input end of the voltage conversion chip U12 is connected with an output end of a positive power supply, a voltage output end of the voltage conversion chip U12 is connected with one end of the inductor L2 through the inductor L1, the other end of the inductor L2 outputs the first working power supply, a common end between the inductor L1 and the inductor L2 is sequentially connected with the resistor R2 and the resistor R3 in series, the common end between the resistor R2 and the resistor R3 is grounded, and a feedback signal input end of the voltage conversion chip U12 is connected.

5. The power supply circuit in a static var compensation device according to claim 4, wherein a freewheeling diode VD4 is reversely connected between a common terminal and a ground terminal between a voltage output terminal of the voltage conversion chip U12 and the inductor L1, and a capacitor C12 and a capacitor C15 which are arranged in parallel are connected between the common terminal and the ground terminal between the inductor L1 and the inductor L2.

6. The power supply circuit in the static var compensation device according to claim 3, wherein the second voltage conversion circuit comprises an LDO voltage stabilizing chip D2, a voltage input end of the LDO voltage stabilizing chip D2 is connected with an output end of the first working power supply, a voltage output end of the LDO voltage stabilizing chip outputs the second working power supply, a capacitor C8, a capacitor C9 and a capacitor C10 are further connected between the voltage output end of the LDO voltage stabilizing chip and a grounding end, and a diode VD1 is reversely connected between the voltage output end of the LDO voltage stabilizing chip and the voltage input end thereof.

7. The power supply circuit in the static var compensation device according to claim 1, wherein the positive reference level conversion circuit comprises a voltage regulator N3, an anode of the voltage regulator N3 is grounded, a cathode of the voltage regulator N3 outputs the positive reference level, the cathode of the voltage regulator N3 is connected with an output end of the positive power supply after being connected with a resistor R7, a resistor R8, a resistor R9 and a resistor R10 in parallel, a reference electrode of the voltage regulator N3 is connected with a cathode of the resistor R20 in series, a reference electrode of the voltage regulator N3 is grounded after being connected with a resistor R24, and a capacitor C25 is connected between the anode and the cathode of the voltage regulator N3.

8. The power supply circuit in the static var compensation device according to claim 1, wherein the negative reference level conversion circuit comprises a voltage regulator N4, an anode of the voltage regulator N4 is connected with a negative and positive power supply, a cathode of the voltage regulator N4 outputs the negative reference level, the cathode of the voltage regulator N4 is grounded after being connected with a resistor R11, a resistor R12, a resistor R13 and a resistor R14 in parallel, a reference electrode of the voltage regulator N4 is connected with a cathode of the voltage regulator N4 after being connected with a resistor R21 in series, a reference electrode of the voltage regulator N3 is connected with a negative power supply through a resistor R25, and a capacitor C26 is connected between the anode and the cathode of the voltage regulator N3.

9. The power supply circuit in the static var compensation device according to claim 1, wherein the reference voltage conversion circuit comprises a reference voltage chip U1, an input end of the reference voltage chip U1 is connected with a resistor R16 and an output end of the third voltage conversion circuit through a parallel resistor R15, an input end of the reference voltage chip U1 is connected with a sleep control end, an output end of the reference voltage chip U1 outputs the reference power supply, an input end of the reference voltage chip U1 is connected with a ground end through a parallel capacitor C22 and a parallel capacitor C23, and an output end of the reference voltage chip U1 is connected with the ground end through a parallel capacitor C24 and a parallel capacitor C21.

10. A power supply circuit in a static var compensation apparatus according to any of claims 1-9, characterized in that said first voltage value is 15V, second voltage value is 3.3V, third voltage value is 1.8V, fourth voltage value and fifth voltage value are 5V, sixth voltage value is 3V.