CN109245160B - Light storage grid-connected control method and device for stabilizing photovoltaic power fluctuation - Google Patents

Abstract

The invention relates to a control method and device for grid-connected optical storage for smoothing photovoltaic power fluctuations. The method includes the following steps: 1) collecting the grid-connected voltage of the hybrid optical-storage microgrid system; 2) when the grid-connected voltage is greater than or equal to the first set value and less than or equal to the second set value, it is determined that the grid-connected voltage is in normal state In the mode, the first constant voltage control is performed on the DC/AC, the MPPT control is performed on the photovoltaic DC/DC, the first filter smoothing control is performed on the battery DC/DC, and the supercapacitor DC/DC is subjected to hot backup control; 3) When connected to the grid When the voltage is lower than the first set value, it is determined to be in low-voltage grid-connected mode, reactive power given control and current limiting control are performed on DC/AC, power limiting control is performed on photovoltaic DC/DC, and battery DC/DC is heated. Backup control, the second constant voltage control is performed on the super capacitor DC/DC. The present invention finely controls DC/AC, photovoltaic DC/DC, battery DC/DC and supercapacitor DC/DC in normal grid-connected mode and low-voltage grid-connected mode, effectively suppressing the failure of the hybrid optical-storage micro-grid system. Power fluctuations in mesh mode.

Description

Optical storage grid-connected control method and device for smoothing photovoltaic power fluctuations

technical field

The invention belongs to the technical field of grid-connected control of optical storage, and particularly relates to a control method and device for grid-connected optical storage for smoothing photovoltaic power fluctuations.

Background technique

In recent years, the installed capacity of new energy sources such as photovoltaics and wind power has grown unprecedentedly. However, due to the inherent volatility, randomness, and undispatchability of distributed generation, it has created challenges to the stability of the power grid, and grid-connected power quality has emerged. A series of problems, such as poor distribution and difficult consumption, limit the high penetration rate access and effective utilization of distributed generation.

In response to the above problems encountered in the development of distributed energy, energy storage has brought us the dawn. Energy storage can be used as a load to charge when electricity consumption is low, and can be used as a power source to discharge when electricity consumption peaks, which can effectively stabilize power fluctuations. It can also participate in the frequency and voltage regulation and demand response of the power grid, realize the large-scale and high-penetration access of distributed power generation, and support distributed power generation and microgrids.

The hybrid solar-storage microgrid system includes a DC power supply system composed of a photovoltaic power generation system and an energy storage system and an AC power supply system composed of a DC/AC converter, and the energy storage system includes a battery system and/or a supercapacitor system. For example, the Chinese patent application document with the application publication number CN103078340A discloses a photovoltaic-storage hybrid microgrid system including a photovoltaic power generation system, a battery system, a supercapacitor system system and an AC power supply system. However, for this hybrid microgrid system, the document does not effectively distinguish the grid-connected mode in which the hybrid microgrid system is located, nor does it identify the DC/DC converters corresponding to batteries and the DC/DC converters corresponding to supercapacitors. , The DC/DC converters and DC/AC converters corresponding to photovoltaics are finely controlled, and the smooth operation of the power grid in the grid-connected mode of the photovoltaic-storage hybrid microgrid system cannot be guaranteed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a photovoltaic power storage grid-connected control method and device for smoothing photovoltaic power fluctuations, which are used to solve the problem of large power grid fluctuations in the grid-connected mode of the existing photovoltaic-storage hybrid microgrid system.

In order to solve the above-mentioned technical problems, the technical scheme of the present invention is:

The invention provides a photovoltaic power storage grid-connected control method for stabilizing photovoltaic power fluctuations. The optical storage hybrid micro-grid system targeted by the method includes photovoltaic panels, photovoltaic DC/DC converters connected to the photovoltaic panels, batteries, and a battery connected to the batteries. Battery DC/DC converters, supercapacitors and supercapacitor DC/DC converters connected to supercapacitors, photovoltaic DC/DC converters, battery DC/DC converters and supercapacitor DC/DC converters all use DC/AC conversion The solar-storage grid-connected control method for smoothing photovoltaic power fluctuations includes the following steps: 1) collecting the grid-connected voltage of the hybrid photovoltaic-storage microgrid system; 2) when the grid-connected voltage of the hybrid photovoltaic-storage microgrid system When it is greater than or equal to the first set value and less than or equal to the second set value, it is determined that the hybrid optical-storage microgrid system is in the normal grid-connected mode, and the DC/AC converter is controlled at a first constant voltage, and the photovoltaic DC/DC The converter performs MPPT control, performs the first filtering and smoothing control for the battery DC/DC converter, and performs hot backup control for the supercapacitor DC/DC converter; 3) When the grid-connected voltage of the optical-storage hybrid microgrid system is lower than the first When the value is set, it is judged that the hybrid solar-storage microgrid system is in the low-voltage grid-connected mode, and the DC/AC converter is controlled by reactive power given control and current limit control, and the photovoltaic DC/DC converter is controlled by the power limit, and the battery The DC/DC converter performs hot standby control, and the second constant voltage control is performed on the supercapacitor DC/DC converter.

The beneficial effects of the method of the invention are as follows: the fine control of DC/AC, photovoltaic DC/DC, battery DC/DC and super capacitor DC/DC in the optical storage and power generation system in the low-voltage grid-connected mode in the normal grid-connected mode is realized, The power fluctuation in the grid-connected mode of the optical-storage hybrid microgrid system is effectively suppressed.

Further, when the scheduling command is received in the grid-connected mode, the present invention also provides more refined DC/AC, photovoltaic DC/DC, battery DC/DC and super capacitor DC/DC in the photovoltaic power generation system. control, in the step 2), if a scheduling instruction is detected, it is determined that the hybrid optical-storage microgrid system is in the scheduling grid-connected mode, the DC/AC converter is scheduled and operated, and the photovoltaic DC/DC converter is controlled by MPPT, The third constant voltage control is performed on the battery DC/DC converter, and the second filter smoothing control is performed on the supercapacitor DC/DC converter.

Further, the present invention proposes a method for using a high-pass filter to achieve photovoltaic fluctuation power smoothing and in order to improve the service life of the battery, the first filtering and smoothing control is realized by a high-pass filter, and the time constant of the high-pass filter changes according to the change of the remaining battery power. and change.

Further, the present invention provides a specific method of adjusting the time constant of the high-pass filter according to the remaining power of the battery, which better improves the service life of the lithium battery. The time constant of the high-pass filter changes according to the change of the remaining power of the battery as: : When the battery is in the charging state, if the remaining battery power is greater than or equal to the first remaining power setting value, the time constant for controlling the high-pass filter decreases with the increase of the remaining battery power; when the battery is in the discharging state , if the remaining battery power is between the first remaining power setting value and the second remaining power setting value, the time constant for controlling the high-pass filter decreases as the remaining battery power decreases.

The present invention also provides an optical storage grid-connected control device for smoothing photovoltaic power fluctuations, the device includes a processor, a memory, and a computer program stored in the memory and executable on the processor, the processor executing the computer The following steps are implemented during the program: 1) Collect the grid-connected voltage of the hybrid optical-storage microgrid system; 2) When the grid-connected voltage of the hybrid optical-storage microgrid system is greater than or equal to the first set value and less than or equal to the second set value When the hybrid microgrid system is determined to be in the normal grid-connected mode, the first constant voltage control is performed on the DC/AC converter, the MPPT control is performed on the photovoltaic DC/DC converter, and the first filter is performed on the battery DC/DC converter. Smoothing control to perform hot backup control of the supercapacitor DC/DC converter; 3) When the grid-connected voltage of the optical-storage hybrid microgrid system is lower than the first set value, it is determined that the optical-storage hybrid microgrid system is connected to the grid at a low voltage The mode is to perform reactive power given control and current limiting control for DC/AC converters, power limit control for photovoltaic DC/DC converters, hot backup control for battery DC/DC converters, and DC/DC conversion for super capacitors. The controller performs the second constant voltage control.

The beneficial effects of the device of the present invention are as follows: the fine control of DC/AC, photovoltaic DC/DC, battery DC/DC and super capacitor DC/DC in the optical storage and power generation system in the low-voltage grid-connected mode in the normal grid-connected mode is realized, The power fluctuation in the grid-connected mode of the optical-storage hybrid microgrid system is effectively suppressed.

Further, when the scheduling command is received in the grid-connected mode, the present invention also provides more refined DC/AC, photovoltaic DC/DC, battery DC/DC and super capacitor DC/DC in the photovoltaic power generation system. control, in the step 2), if a scheduling instruction is detected, it is determined that the hybrid optical-storage microgrid system is in the scheduling grid-connected mode, the DC/AC converter is scheduled and operated, and the photovoltaic DC/DC converter is controlled by MPPT, The third constant voltage control is performed on the battery DC/DC converter, and the second filter smoothing control is performed on the supercapacitor DC/DC converter.

Further, the present invention proposes a device for using a high-pass filter to achieve photovoltaic fluctuation power smoothing and in order to improve the service life of the battery, the first filtering and smoothing control is realized by a high-pass filter, and the time constant of the high-pass filter changes according to the remaining battery power. and change.

Further, the present invention provides a specific method of adjusting the time constant of the high-pass filter according to the remaining power of the battery, which better improves the service life of the lithium battery. The time constant of the high-pass filter changes according to the change of the remaining power of the battery as: : When the battery is in the charging state, if the remaining battery power is greater than or equal to the first remaining power setting value, the time constant for controlling the high-pass filter decreases with the increase of the remaining battery power; when the battery is in the discharging state , if the remaining battery power is between the first remaining power setting value and the second remaining power setting value, the time constant for controlling the high-pass filter decreases as the remaining battery power decreases.

Description of drawings

FIG. 1 is a schematic structural diagram of an existing optical-storage hybrid microgrid system;

2 is a schematic diagram of a DC/AC converter control method in a normal grid-connected mode in Embodiment 1 of the method of the present invention;

3 is a schematic diagram of a photovoltaic DC/DC converter control method in a normal grid-connected mode in Embodiment 1 of the method of the present invention;

4 is a schematic diagram of a control method for a battery DC/DC converter in a normal grid-connected mode in Embodiment 1 of the method of the present invention;

5 is a schematic diagram of a method for controlling a supercapacitor DC/DC converter in a normal grid-connected mode in Embodiment 1 of the method of the present invention;

6 is a circuit diagram of a high-pass filter in a normal grid-connected mode in Embodiment 1 of the method of the present invention;

7 is a graph of battery SOC-time constant in a normal grid-connected mode in Embodiment 1 of the method of the present invention;

8 is a schematic diagram of a method for controlling a DC/AC converter in a low-voltage grid-connected mode in Embodiment 1 of the present invention;

9 is a schematic diagram of a photovoltaic DC/DC converter control method in a low-voltage grid-connected mode in Embodiment 1 of the method of the present invention;

10 is a schematic diagram of a control method of a battery DC/DC converter in a low-voltage grid-connected mode in Embodiment 1 of the method of the present invention;

11 is a schematic diagram of a method for controlling a supercapacitor DC/DC converter in a low-voltage grid-connected mode in Embodiment 1 of the present invention;

12 is a control logic diagram of three grid-connected modes in method Embodiment 2 of the present invention;

13 is a schematic diagram of a DC/AC converter control method in a scheduling grid-connected mode in Embodiment 2 of the method of the present invention;

14 is a schematic diagram of a method for controlling a battery DC/DC converter in a scheduling grid-connected mode in Embodiment 2 of the method of the present invention;

15 is a schematic diagram of a method for controlling a supercapacitor DC/DC converter in a scheduling grid-connected mode in Embodiment 2 of the method of the present invention.

Detailed ways

The embodiments of the present invention will be further described below with reference to the accompanying drawings.

The photovoltaic power storage grid-connected control method for smoothing photovoltaic power fluctuations of the present invention is described by taking the energy storage system including a lithium battery system and a super capacitor system as an example, and the corresponding structure diagram of the photovoltaic storage hybrid microgrid is shown in FIG. , Photovoltaic DC/DC converters connected to photovoltaic panels, lithium batteries, battery DC/DC converters connected to batteries, supercapacitors and supercapacitor DC/DC converters connected to supercapacitors, photovoltaic DC/DC converters, Both the battery DC/DC converter and the supercapacitor DC/DC converter are connected to the AC grid through the DC/AC converter.

Embodiment 1 of the photovoltaic power storage grid-connected control method for smoothing photovoltaic power fluctuations:

The photovoltaic power storage grid-connected control method for smoothing photovoltaic power fluctuations in this embodiment includes the following steps: collecting the grid-connected voltage of the photovoltaic-storage hybrid microgrid system, and judging that the photovoltaic-storage hybrid microgrid system is in normal grid-connection according to the range of the grid-connected voltage The mode is still the low-voltage grid-connected mode.

无功给定电流值

需要根据实际情况设定，内环采用dq解耦控制实现并网电流的控制，如图2所示；对光伏DC/DC变换器进行MPPT控制，也即最大功率点控制，是指采集光伏阵列输出的电压U_PV和电流i_PV，通过最大功率点算法(MPPT)将光伏阵列的输出电压U_mppt调整到最佳位置，和实际光伏阵列输出电压U_PV做差，通过PI控制器输出占空比控制光伏DC/DC模块，最终实现光伏阵列的最大功率输出，如图3所示；对电池DC/DC变换器进行第一频率平抑控制，也即中高频平抑控制，是指通过高通滤波器滤除光伏输出功率的低频信号，得到中高频信号作为锂电池DC/DC的给定功率P_batref，除以当前锂电池端电压作为锂电池侧DC/DC给定输出电流i^* _bat，再与实际锂电池侧DC/DC输出电流i_bat做差，通过PI控制输出可变占空比，最后控制锂电池DC/DC实现光储系统的中高频功率平抑，如图4所示；对超级电容DC/DC变换器进行热备控制，是指此时超级电容DC/DC处于工作状态，但是输出电流为零，

为超级电容侧DC/DC给定充放电电流，i_C为超级电容侧DC/DC实际充放电电流，如图5所示。When the grid-connected voltage of the hybrid optical-storage microgrid system is greater than or equal to the first set value and less than or equal to the second set value, it is determined that the hybrid optical-storage microgrid system is in the normal grid-connected mode, and the DC/AC converter is The first constant voltage control, the voltage outer loop is made by the difference between the given DC bus voltage value U _DCref and the actual collected DC bus voltage value U _DC , and the difference value outputs the active given current value through the PI controller

Reactive power given current value

It needs to be set according to the actual situation. The inner loop adopts dq decoupling control to realize the control of grid-connected current, as shown in Figure 2; MPPT control of photovoltaic DC/DC converters, that is, maximum power point control, refers to the collection of photovoltaic arrays. The output voltage U _PV and current i _PV are adjusted to the optimal position by the maximum power point algorithm (MPPT), and the output voltage U _mppt of the photovoltaic array is adjusted to the best position, and the difference is made with the actual photovoltaic array output voltage U _PV , and the output duty is output through the PI controller. By controlling the photovoltaic DC/DC module, the maximum power output of the photovoltaic array is finally realized, as shown in Figure 3; the first frequency suppression control is performed on the battery DC/DC converter, that is, the medium and high frequency suppression control, which refers to the high-pass filter. Filter out the low-frequency signal of the photovoltaic output power, obtain the medium-high frequency signal as the given power P _batref of the DC/DC of the lithium battery, divide it by the current terminal voltage of the lithium battery as the given output current i ^* _bat of the DC/DC on the lithium battery side, and then compare it with the actual The DC/DC output current i _bat on the lithium battery side is poor, and the output variable duty ratio is controlled by PI, and finally the DC/DC of the lithium battery is controlled to achieve the medium and high frequency power stabilization of the optical storage system, as shown in Figure 4; for the super capacitor DC The /DC converter performs hot standby control, which means that the supercapacitor DC/DC is in the working state at this time, but the output current is zero,

is the given charge and discharge current of the supercapacitor side DC/DC, and i _C is the actual charge and discharge current of the supercapacitor side DC/DC, as shown in Figure 5.

In the normal grid-connected mode, the medium and high frequency suppression control of the lithium battery DC/DC converter is mainly realized by the high-pass filter. When the battery is charged, the lithium battery is discharged when it is negative, and a linear relationship between the time constant τ and the SOC of the lithium battery is established. Figure 6 is a circuit diagram of a second-order high-pass filter. According to this circuit, the transfer function H(s) is established:

Let: time constant τ=RC,

通带截止频率和时间常数成反比，时间常数越小，通带截止频率越大，让锂电池补偿的功率越小。passband cutoff frequency

The pass-band cut-off frequency is inversely proportional to the time constant. The smaller the time constant, the larger the pass-band cut-off frequency, and the smaller the compensation power of the lithium battery.

According to this principle, the SOC-τ working curve is drawn. As shown in Figure 7, when the battery is in the charging state, when the remaining battery power is less than the first remaining power setting value a, the time constant of the high-pass filter is τ ₂ = R ₂ C ₂ ; if the remaining battery power is greater than or equal to the first remaining power setting value a, the time constant for controlling the high-pass filter decreases as the remaining battery power increases.

When the battery is in the discharge state, when the remaining battery power is greater than the second remaining power setting value c, the time constant of the high-pass filter is τ ₂ =R ₂ C ₂ ; if the remaining battery power is at the first remaining power setting value c When between a and the second remaining power setting value c, the time constant for controlling the high-pass filter decreases with the decrease of the remaining battery power; when the remaining battery power is less than the first remaining power setting value a, the high-pass filtering The time constant of the device is τ ₁ =R ₁ C ₁ . According to Figure 7, the lithium battery charging curve equation and the lithium battery discharging curve equation are designed.

Lithium battery charging curve equation:

Lithium battery discharge curve equation:

e_d为电网相电压有效值，P^*为实际要求输出的有功功率，因此实际输出有功和无功分别由实际情况给定，内环控制为dq解耦控制，如图8所示；对光伏DC/DC变换器进行限功率控制，是指通过MPPT限功率算法，即增加或者减小U_mppt达到限光伏输出功率的目的，如图9所示；对电池DC/DC变换器进行热备控制，锂电池侧控制电流给定为零，此时锂电池DC/DC控制处于运行状态，但是不输出电流，如图10所示；对超级电容DC/DC变换器进行第二定电压控制，是指电压外环采用稳定直流母线电压，电流内环控制超级电容侧的电流的输出，最后通过控制PWM占空比实现稳定直流母线电压的目的，如图11所示。When the grid-connected voltage of the optical-storage hybrid microgrid system is lower than the first set value, it is determined that the optical-storage hybrid microgrid system is in the low-voltage grid-connected mode, and the DC/AC converter is given reactive power control and current limiting control. ,

e _d is the effective value of the grid phase voltage, P ^* is the actual required output active power, so the actual output active power and reactive power are respectively given by the actual situation, and the inner loop control is dq decoupling control, as shown in Figure 8; Power limiting control of DC/DC converters refers to the purpose of limiting photovoltaic output power by increasing or decreasing U _mppt through the MPPT power limiting algorithm, as shown in Figure 9; hot-standby control of battery DC/DC converters , the control current on the lithium battery side is given zero, at this time the lithium battery DC/DC control is in the running state, but no current is output, as shown in Figure 10; the second constant voltage control of the super capacitor DC/DC converter is It means that the voltage outer loop adopts stable DC bus voltage, and the current inner loop controls the output of the current on the supercapacitor side. Finally, the purpose of stabilizing the DC bus voltage is achieved by controlling the PWM duty cycle, as shown in Figure 11.

In this embodiment, a lithium battery is used, and as another embodiment, a lead-acid battery or the like can also be used.

In this embodiment, a is 10%, b is 95%, and c is 97%; as other embodiments, values close to the above values can also be taken, for example, a is 10.1%, b is 94.9%, and c is 97.2%.

In this embodiment, a linear relationship between the time constant τ of the second-order high-pass filter and the SOC of the lithium battery is established. As other implementations, a first-order high-pass filter, a third-order high-pass filter, etc. When the first-order high-pass filter is used, it is only necessary to adjust the corresponding time constant according to the remaining power of the lithium battery; in addition, the time constant τ in the middle stage can be adjusted not according to the above linear relationship, but set according to the remaining power of the lithium battery in the middle stage. Multiple piecewise time constants.

This embodiment abandons the method of using a fixed time constant in the intermediate stage, is more flexible, and improves the service life of the lithium battery.

This embodiment realizes the refined control of DC/AC, photovoltaic DC/DC, battery DC/DC, and supercapacitor DC/DC in the photovoltaic storage and power generation system in the low-voltage grid-connected mode in the normal grid-connected mode, effectively suppressing the Power fluctuation in grid-connected mode of a hybrid optical-storage microgrid system.

Embodiment 2 of the photovoltaic power storage grid-connected control method for smoothing photovoltaic power fluctuations:

The difference between this embodiment and the above-mentioned embodiment is that this embodiment also includes fine-grained control in the scheduling grid-connected mode, as shown in FIG. 12 .

如图13所示；对光伏DC/DC变换器仍进行MPPT控制，如图3所示；对锂电池DC/DC变换器进行稳定直流母线电压控制，即第三定电压控制，是指电压外环采用稳定直流母线电压，电流内环控制锂电池侧的电流的输出，最后通过控制PWM占空比实现稳定直流母线电压的目的，如图14所示；对超级电容DC/DC变换器进行第二频率平抑控制，也即高频平抑控制，通过高通滤波器得到光伏功率的高频信号P_Cref，经过计算得到超级电容侧DC/DC给定充放电电流

和超级电容侧DC/DC实际充放电电流i_c做差，通过PI控制器调节，输出调制波，通过PWM控制输出可变占空比，最后实现超级电容给定输出功率的控制，如图15所示。对超级电容DC/DC变换器进行高频平抑控制可通过设置高通滤波器的通带截止频率减小滤波信号的带宽，实现高频信号滤除作用。When the grid-connected voltage of the optical-storage hybrid microgrid system is greater than or equal to the first set value and less than or equal to the second set value, if there is a dispatch command, it is judged that the photovoltaic-storage power generation system is in the dispatch grid-connected mode, and the DC/AC The inverter performs scheduling operation control. When receiving the output command from the upper-level scheduling system, the active power output P _ref and reactive power output can be set according to the requirements.

As shown in Figure 13; MPPT control is still performed on the photovoltaic DC/DC converter, as shown in Figure 3; The loop adopts the stable DC bus voltage, the current inner loop controls the output of the current on the lithium battery side, and finally achieves the purpose of stabilizing the DC bus voltage by controlling the PWM duty cycle, as shown in Figure 14; The second frequency suppression control, that is, the high frequency suppression control, obtains the high frequency signal P _Cref of the photovoltaic power through the high-pass filter, and obtains the DC/DC given charge and discharge current of the super capacitor side through calculation

The difference with the actual charge and discharge current _ic of the supercapacitor side DC/DC is adjusted by the PI controller, the modulated wave is output, and the variable duty cycle is output by the PWM control, and finally the control of the given output power of the supercapacitor is realized, as shown in Figure 15. shown. The high-frequency suppression control of the supercapacitor DC/DC converter can reduce the bandwidth of the filtered signal by setting the passband cutoff frequency of the high-pass filter to achieve high-frequency signal filtering.

This embodiment realizes the refined control of DC/AC, photovoltaic DC/DC, battery DC/DC, and supercapacitor DC/DC in the photovoltaic storage and power generation system in the low-voltage grid-connected mode in the dispatching grid-connected mode, effectively suppressing the Power fluctuation in grid-connected mode of a hybrid optical-storage microgrid system.

The embodiment of the photovoltaic power storage grid-connected control device for smoothing photovoltaic power fluctuations

The photovoltaic power grid-connected control device for smoothing photovoltaic power fluctuations in this embodiment includes a processor, a memory, and a computer program stored in the memory and running on the processor, and the processor implements smoothing photovoltaic power when executing the computer program. Steps in an embodiment of an optical storage grid-connected control method for power fluctuations.

Since the relevant steps have been described in detail in the embodiments of the photovoltaic power storage grid-connected control method for stabilizing photovoltaic power fluctuations, they will not be repeated here.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art, without departing from the scope of the technical solution of the present invention, can make some changes or modifications by using the methods and technical contents disclosed above to be equivalent embodiments of equivalent changes, but all those that do not depart from the technical solution of the present invention It should be noted that any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solutions of the present invention.

Claims (4)

1. A light storage grid-connected control method for stabilizing photovoltaic power fluctuation comprises a photovoltaic panel, a photovoltaic DC/DC converter connected with the photovoltaic panel, a battery DC/DC converter connected with the battery, a super capacitor and a super capacitor DC/DC converter connected with the super capacitor, wherein the photovoltaic DC/DC converter, the battery DC/DC converter and the super capacitor DC/DC converter are all connected with an alternating current power grid through DC/AC converters, and is characterized in that the light storage grid-connected control method for stabilizing photovoltaic power fluctuation comprises the following steps:

1) collecting grid-connected voltage of the light-storage hybrid micro-grid system;

2) when the grid-connected voltage of the light-storage hybrid micro-grid system is larger than or equal to a first set value and smaller than or equal to a second set value, the light-storage hybrid micro-grid system is judged to be in a normal grid-connected mode, first fixed voltage control is carried out on a DC/AC converter, MPPT control is carried out on a photovoltaic DC/DC converter, first filtering stabilization control is carried out on a battery DC/DC converter, and hot standby control is carried out on a super-capacitor DC/DC converter;

3) when the grid-connected voltage of the light storage mixed micro-grid system is lower than a first set value, the light storage mixed micro-grid system is judged to be in a low-voltage grid-connected mode, reactive power setting control and current limiting control are carried out on a DC/AC converter, power limiting control is carried out on a photovoltaic DC/DC converter, hot standby control is carried out on a battery DC/DC converter, and second voltage setting control is carried out on a super capacitor DC/DC converter;

the first filtering stabilizing control is realized by a second-order high-pass filter, and the second-order high-pass filter is sequentially provided with two RC branches from an input end to an output end; the time constant of the second-order high-pass filter changes according to the change of the residual capacity of the battery, and when the battery is in a charging state:

when the battery is in a discharge state:

where τ is the time constant of the second order high pass filter, τ₁＝R₁C₁，τ₂＝R₂C₂SOC is a remaining battery capacity, a is a first remaining capacity setting value, b is a third remaining capacity setting value, c is a second remaining capacity setting value, and R is₁Is the resistance value in the first RC branch, C₁The capacitance value in the first RC branch is obtained; r₂Is the resistance value, C, in the second RC branch₂Is the capacitance in the second RC branch.

2. The optical storage grid-connected control method for stabilizing photovoltaic power fluctuation according to claim 1, wherein in the step 2), if a scheduling instruction is detected, it is determined that the optical storage hybrid microgrid system is in a scheduling grid-connected mode, the DC/AC converter is controlled according to the scheduling instruction, MPPT control is performed on the photovoltaic DC/DC converter, third constant voltage control is performed on the battery DC/DC converter, and second filtering stabilization control is performed on the super capacitor DC/DC converter.

3. A grid-connected photovoltaic control apparatus for stabilizing photovoltaic power fluctuation, the apparatus comprising a processor and a memory, and a computer program stored in the memory and operable on the processor, the processor implementing the following steps when executing the computer program:

1) collecting grid-connected voltage of the light-storage hybrid micro-grid system;

2) when the grid-connected voltage of the light-storage hybrid micro-grid system is larger than or equal to a first set value and smaller than or equal to a second set value, the light-storage hybrid micro-grid system is judged to be in a normal grid-connected mode, first fixed voltage control is carried out on a DC/AC converter, MPPT control is carried out on a photovoltaic DC/DC converter, first filtering stabilization control is carried out on a battery DC/DC converter, and hot standby control is carried out on a super-capacitor DC/DC converter;

3) when the grid-connected voltage of the light storage mixed micro-grid system is lower than a first set value, the light storage mixed micro-grid system is judged to be in a low-voltage grid-connected mode, reactive power setting control and current limiting control are carried out on a DC/AC converter, power limiting control is carried out on a photovoltaic DC/DC converter, hot standby control is carried out on a battery DC/DC converter, and second voltage setting control is carried out on a super capacitor DC/DC converter;

the first filtering stabilizing control is realized by a second-order high-pass filter, and the second-order high-pass filter is sequentially provided with two RC branches from an input end to an output end; the time constant of the second-order high-pass filter changes according to the change of the residual capacity of the battery, and when the battery is in a charging state:

when the battery is in a discharge state:

where τ is the time constant of the second order high pass filter, τ₁＝R₁C₁，τ₂＝R₂C₂SOC is a remaining battery capacity, a is a first remaining capacity setting value, b is a third remaining capacity setting value, c is a second remaining capacity setting value, and R is₁Is the resistance value in the first RC branch, C₁The capacitance value in the first RC branch is obtained; r₂In the second RC branchResistance value of C₂Is the capacitance in the second RC branch.

4. The grid-connected optical storage control device for stabilizing photovoltaic power fluctuation according to claim 3, wherein in the step 2), if a scheduling instruction is detected, it is determined that the hybrid optical storage microgrid system is in a scheduling grid-connected mode, the DC/AC converter is controlled according to the scheduling instruction, the MPPT control is performed on the photovoltaic DC/DC converter, the third constant voltage control is performed on the battery DC/DC converter, and the second filtering stabilization control is performed on the super capacitor DC/DC converter.

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