CN210780117U - A composite energy storage power stabilization system for bidirectional converters - Google Patents

Abstract

The utility model relates to a composite energy storage power stabilization system of a bidirectional converter, which is connected between a wind power generation system and a load, and comprises a bidirectional power converter, wherein the bidirectional power converter comprises a conversion controller, a pulsation compensation circuit, and a converter. A storage battery connected to a controller, the pulsation compensation circuit includes a switching device and a super capacitor, and the super capacitor is connected to the conversion controller through the switching device. The utility model combines the super capacitor and the battery, is connected in parallel with the wind power generation system and the load through the Buck/Boost bidirectional converter, and adopts the PWM control mode to control the return flow, which can stabilize the direct current voltage of the system circuit, and utilizes the complementary power of the super capacitor and the battery. This increases the service life of the battery.

Description

A composite energy storage power stabilization system for bidirectional converters

technical field

The utility model relates to the technical field of power stabilization, in particular to a composite energy storage power stabilization system of a bidirectional converter.

Background technique

The development and utilization of "green energy" and the continuous advancement of the realization of sustainable development goals, distributed power generation mainly relies on new energy generation from wind energy and solar lamps. Compared with traditional energy sources, there are random and intermittent characteristics, but there will be certain Power fluctuations have an impact on the power grid, which brings great challenges to the safe operation of the power grid.

Utility model content

The purpose of the utility model is to improve the deficiencies existing in the prior art, combined with the method of composite energy storage of super capacitors and batteries, a composite energy storage power stabilization system of a bidirectional converter is proposed. The inverters are connected in parallel and connected to the wind power generation system and the load at the same time. The PWM control method is used to control the return flow, which can stabilize the DC voltage of the system loop, and improve the service life of the battery by complementing the supercapacitor and the battery.

The use of supercapacitors and batteries for composite energy storage is used in distributed power generation, power storage, microgrids and other fields. From the characteristics of batteries and supercapacitors, the two have strong complementarity in technical performance. Supercapacitors have high power density, high charging efficiency, and long cycle life. They are very suitable for high-power discharge and cyclic charge-discharge. However, the energy density is relatively low, and it is not suitable for large-scale power storage. On the contrary, the battery has high energy density, but low power density, low charging and discharging efficiency, short cycle life, and is sensitive to the charging and discharging process. The adaptability of high-power charging and discharging and frequent discharging is not strong. Supercapacitors can make up for the insufficiency of the battery and provide the service life of the battery.

In order to achieve the above purpose of the utility model, the embodiments of the present utility model provide the following technical solutions:

A composite energy storage power stabilization system of a bidirectional converter is connected between a wind power generation system and a load, and includes a bidirectional power converter, wherein the bidirectional power converter includes a conversion controller, a pulsation compensation circuit, and a power converter connected to the conversion controller. In the battery, the pulsation compensation circuit includes a switching device and a super capacitor, and the super capacitor is connected to the conversion controller through the switching device.

The conversion controller changes the on-off of the switching device, so that the wind power generation system supplies power to the load, charges the battery, charges the supercapacitor, or the supercapacitor supplies power to the load and the battery. The current is split at the switching device, allowing the DC component to enter the battery and the pulsating component to enter the supercapacitor.

Further, in order to better realize the present invention, the switch device includes a switch S1 and a switch S2, and the switch S1 and the switch S2 are respectively connected to the conversion controller.

Further, in order to better realize the present invention, the pulsation compensation circuit further includes a capacitor C1, a capacitor C2, and an inductor L2, the capacitor C1 is connected in parallel with the super capacitor, the capacitor C2 is connected in parallel with the switch S2, and the inductor is connected in parallel with the switch S2. L2 is connected in series with the supercapacitor.

Further, in order to better realize the utility model, the conversion controller includes a low-pass filter, an integral controller, and a PWM pulse width modulation circuit connected in sequence, and the low-pass filter is connected to the output end of the wind power generation system. connection, the PWM pulse width modulation circuit is respectively connected with the switch S1 and the switch S2.

PWM control is a technology that modulates the width of the pulse. The voltage and frequency of the signal are controlled by changing the width and period of the pulse, which is referred to as pulse width modulation technology. Its working principle is to modulate the width information of the equal-amplitude pulse. The waveform after the pulse width modulation is a pulse with the same amplitude, which is used to replace the required waveform and mainly controls the on and off states of the switching device. By analyzing the frequency, period and pulse number of the required waveform, the interval and width between pulses in the PWM signal can be accurately calculated, thereby obtaining a stable DC output voltage.

Further, in order to better realize the present invention, the bidirectional power converter further includes an IGBT drive circuit, the input end of the IGBT drive circuit is connected with the output end of the PWM pulse width modulation circuit, and the output end of the IGBT drive circuit is connected to the output end of the PWM pulse width modulation circuit. They are respectively connected to switch S1 and switch S2.

Further, in order to better realize the present utility model, the bidirectional power converter further comprises a crystal oscillator, a first counter, and a second counter connected in sequence, and the crystal oscillator is connected to the output end of the wind power generation system, The second counter is connected to a low pass filter.

Furthermore, in order to better realize the present invention, the bidirectional power converter further includes a voltage follower, and the voltage follower is connected between the low-pass filter and the integral controller.

Furthermore, in order to better realize the present invention, an inverter is connected between the PWM pulse width modulation circuit and the switch S1.

Compared with the prior art, the beneficial effects of the present utility model:

The utility model combines the super capacitor and the battery, is connected in parallel with the wind power generation system and the load through the Buck/Boost bidirectional converter, and adopts the PWM control mode to control the return flow, which can stabilize the direct current voltage of the system circuit, and utilizes the complementary power of the super capacitor and the battery. In this way, the number of charging and discharging of the battery is reduced, and the service life of the battery is improved.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings that need to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention. Therefore, it should not be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a block diagram of a power stabilization system of a bidirectional converter of the present utility model;

Fig. 2 is the circuit schematic diagram of the bidirectional power converter of the present utility model;

3(a) is a schematic diagram of the current flow path in which the switch S1 is turned off and the switch S2 is turned on when the utility model is in a boost state;

Figure 3(b) is a schematic diagram of the current flow path in which the switch S1 is turned on and the switch S2 is turned off when the present invention is in a boost state;

4(a) is a schematic diagram of the current flow path in which the switch S1 is turned on and the switch S2 is turned off when the utility model is in a Buck state;

Figure 4(b) is a schematic diagram of the current flow path of the switch S1 being turned off and the switch S2 being turned on when the present invention is in a Buck state;

FIG. 5 is a block diagram of a conversion controller module of the present invention;

Fig. 6 is the detailed block diagram of the transformation controller of the utility model;

7 is an internal equivalent circuit diagram of the battery of the present invention;

8 is an internal equivalent circuit diagram of a supercapacitor of the present utility model;

9 is a circuit schematic diagram of an integral controller of the present invention;

FIG. 10 is a schematic diagram of the PWM pulse width modulation circuit and the IGBT drive circuit of the present invention.

Detailed ways

The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. . The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present invention.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures. Meanwhile, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description, and should not be construed as indicating or implying relative importance, or implying the existence of any such entities or operations. The actual relationship or sequence.

Example 1:

The utility model is realized by the following technical solutions. As shown in FIG. 1, a composite energy storage power stabilization system of a bidirectional converter is connected between the wind power generation system and the load, and includes a bidirectional power converter. The bidirectional power conversion The converter includes a conversion controller, a pulsation compensation circuit, and a storage battery connected with the conversion controller. The pulsation compensation circuit includes a switching device and a super capacitor, and the super capacitor is connected with the conversion controller through the switching device. The load is divided into DC load and AC load. The DC load is directly connected to the battery, and the AC load is connected to the battery through the inverter.

The conversion controller changes the on-off of the switching device, so that the wind power generation system supplies power to the load, charges the battery, charges the supercapacitor, or the supercapacitor supplies power to the load and the battery. The current is split at the switching device, allowing the DC component to enter the battery and the pulsating component to enter the supercapacitor.

As shown in FIG. 2 , in detail, the ripple compensation circuit is used to realize the step-up/down change of the conversion controller. The switching device includes a switch S1 and a switch S2, and the ripple compensation circuit further includes a capacitor C1, a capacitor C2, and an inductor. L2, where the capacitor C1 is connected in parallel with the supercapacitor EDLC, and the inductor L2 is connected in series with the supercapacitor. The capacitor C1 and the inductor L2 are used to prevent the current flowing into the supercapacitor from changing suddenly, causing damage to the supercapacitor; the capacitor C2 is connected in parallel with the switch S2 to suppress The switching device generates current and voltage fluctuations when it is turned off; a reactor L1 is connected between the battery and the switching device, and the reactor L1 and the switching device form a bidirectional chopper circuit to control the charging and discharging switching of the supercapacitor.

Figure 7 shows the internal equivalent circuit diagram of the battery. In this embodiment, the battery is a lead-acid battery, where _Cb is the capacitance of the lead-acid battery, _Rp is the dynamic resistance of the lead-acid battery, and _R2c is the lead-acid battery charging. The internal resistance at the time of discharge, R _1d is the overvoltage resistance of the lead-acid battery when it is discharged, and C _d is the overvoltage capacitance of the lead-acid battery.

Figure 8 shows the internal equivalent circuit diagram of the supercapacitor, in which R1 is the equivalent series resistance, which has an important impact on the charging and discharging capacity of the supercapacitor; R2 is the equivalent parallel resistance, which represents the leakage current of the supercapacitor, which has a significant impact on the capacitance of the supercapacitor. The long-term energy storage performance has an important impact.

Figure 5 is a block diagram of a conversion controller in the bidirectional power converter. The conversion controller includes a low-pass filter, an integral controller, and a PWM pulse width modulation circuit connected in sequence. The PWM pulse width modulation The output ends of the circuit are respectively connected with the switch S1 and the switch S2, wherein an inverter is connected between the PWM pulse width modulation circuit and the switch S1.

Figure 2 shows the circuit diagram of the bidirectional power converter, which has two working states: a boost (Buck) and a step-down (Boost). Input is the output of the wind power generation system, load is equivalent to the load, i _s is the output current of the wind power generation system after rectification, is divided into _ib and _ic by the end of the battery, _ib enters the battery, and _{ic enters} the reactance device L1. The low-pass filter LPF extracts i _s for filtering, and after removing the AC pulsation, the DC component i _bref is obtained, and the current i _b of the battery is extracted at the same time, and the error signal Δi _b is obtained by subtracting i _b from i _bref .

When the error signal Δi _b is greater than 0, the system is in a boost state. At this time, when the PWM pulse width modulation circuit controls the switch S1 to be turned off and the switch S2 to be turned on, as shown in Figure 3(a), the current flow path is L1 -S2, L1 stores part of the electric energy; when the control switch S1 is turned on and the switch S2 is turned off, as shown in Figure 3(b), the current flow path is L1-S1-EDLC, L1 will generate back electromotive force, and release the stored electricity, while charging the supercapacitor to absorb the fluctuating power.

When the error signal Δi _b is less than 0, the system is in a Buck state. At this time, when the PWM pulse width modulation circuit controls the switch S1 to be turned on and the switch S2 to be turned off, as shown in Figure 4(a), the EDLC discharges and the current flows. The path is EDLC-S1-L1, and the electromagnetic energy is stored in L1; when the control switch S1 is turned off, the switch S2 is turned on, and the current decreases, as shown in Figure 4(b), the current flow path is L1-S2, and L1 produces a reverse reaction. To the electromotive force, the stored electromagnetic energy is released, and the step-down operation is repeatedly performed to ensure that the battery can be charged at an approximate constant current, thereby obtaining a stable DC output voltage.

Further, the bidirectional power converter further includes a crystal oscillator, a first counter, a second counter, a voltage follower, and an IGBT drive circuit, the crystal oscillator, the first counter, and the second counter are connected in sequence, and the first counter is connected in sequence. The output end of the two counters is connected to the low-pass filter, and the voltage follower is connected between the low-pass filter and the integral controller. As shown in FIG. 9, the circuit schematic diagram of the integral controller is shown. The output end of the IGBT is connected to the IGBT drive circuit, the output ends of the IGBT drive circuit are respectively connected to the switch S1 and the switch S2, and the inverter is connected between the PWM pulse width modulation circuit and the IGBT drive circuit, as shown in Figure 10 for the PWM Schematic diagram of pulse width modulation circuit and IGBT drive circuit. At the PWM pulse modulation circuit, a triangular wave generator is also connected.

The PWM pulse modulation circuit realizes control by changing the pulse width of the input signal. The PWM pulse modulation circuit compares the modulated wave compensated by the integral controller with the triangular wave generated by the external triangular wave generator, thereby changing the duty cycle of the pulse width modulation. , so as to output the control signal. The duty cycle (Duty) of PWM control refers to the ratio of the on-time of the switching device to the sum of the on-off and on-off times. :

Wherein t ₁ is the on-time of the switching device, and t ₂ is the off-time of the switching device.

When the system is in the boost state, the relationship between the voltage U ₁ across the battery and the voltage U ₂ across the supercapacitor is: U ₂ =(1-Duty)U ₁ ; when the system is in the Buck state , the relationship between the voltages U ₁ and U ₂ is: U ₂ =Duty*U ₁ . Therefore, the voltage U ₁ (V _b in FIG. 2 ) across the battery can be changed by changing the duty cycle, and the current in the reactor L1 can be changed.

The error signal Δi _b is compensated by the integral controller. It is assumed that the compensated signal passes through the PWM pulse modulation circuit to generate two opposite control signals with a frequency of about 30 kHz and a duty cycle of 0.5 to control the switch S1 and the switch S2 respectively, thereby controlling the super Charge and discharge of capacitors.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited to this. Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (8)

1. The utility model provides a compound energy storage power steady system of bidirectional converter, is connected between wind power generation system and load which characterized in that: the bidirectional power converter comprises a conversion controller, a ripple compensation circuit and a storage battery connected with the conversion controller, wherein the ripple compensation circuit comprises a switching device and a super capacitor, and the super capacitor is connected with the conversion controller through the switching device.

2. The composite energy storage power smoothing system of a bidirectional converter as recited in claim 1, further comprising: the switch device comprises a switch S1 and a switch S2, and the switch S1 and the switch S2 are respectively connected with the conversion controller.

3. The composite energy storage power smoothing system of a bidirectional converter as recited in claim 2, further comprising: the ripple compensation circuit further comprises a capacitor C1, a capacitor C2 and an inductor L2, wherein the capacitor C1 is connected with the super capacitor in parallel, the capacitor C2 is connected with the switch S2 in parallel, and the inductor L2 is connected with the super capacitor in series.

4. The composite energy storage power smoothing system of a bidirectional converter as recited in claim 3, further comprising: the conversion controller comprises a low-pass filter, an integral controller and a PWM (pulse width modulation) circuit which are sequentially connected, the low-pass filter is connected with the output end of the wind power generation system, and the PWM circuit is respectively connected with a switch S1 and a switch S2.

5. The composite energy storage power smoothing system of a bidirectional converter as recited in claim 4, further comprising: the bidirectional power converter further comprises an IGBT driving circuit, wherein the input end of the IGBT driving circuit is connected with the output end of the PWM circuit, and the output end of the IGBT driving circuit is respectively connected with the switch S1 and the switch S2.

6. A composite energy storage power smoothing system for a bidirectional converter as defined in claim 4 or 5, wherein: the bidirectional power converter further comprises a crystal oscillator, a first counter and a second counter which are connected in sequence, the crystal oscillator is connected with the output end of the wind power generation system, and the second counter is connected with the low-pass filter.

7. A composite energy storage power smoothing system for a bidirectional converter as defined in claim 4 or 5, wherein: the bidirectional power converter further comprises a voltage follower connected between the low-pass filter and the integral controller.

8. The composite energy storage power smoothing system of a bidirectional converter as recited in claim 4, further comprising: an inverter is connected between the PWM circuit and the switch S1.

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