A method for reshaping impedance of a grid-connected photovoltaic and storage integrated power generation system

Abstract

The present invention relates to the technical field of grid-connected converter data processing, and specifically to an impedance reshaping method for a grid-connected photovoltaic and storage integrated power generation system. The method collects electrical quantities on the AC side and the DC side of the grid-connected converter to judge the power direction, and decides whether to intervene in an impedance reshaping control module accordingly. When the power is in the positive direction, the DC side voltage is compared with a reference value, the voltage difference is calculated, and an active power compensation value is obtained through a compensation coefficient to reshape the impedance characteristics of the grid-connected converter. The present invention can improve the stability of the system when the power is in the positive direction without changing the main structure of the grid-connected control, simplify the difficulty of parameter setting, and enhance the robustness of the system, and effectively solves the problem of dynamic characteristic difference of the grid-connected photovoltaic and storage integrated power generation system when the power direction changes.

Description

Technical Field

[0001] The present invention relates to the technical field of grid-connected converter data processing, and in particular to an impedance reshaping method for a grid-connected photovoltaic-storage integrated power generation system. Background Art

[0002] With the increase in energy demand and the improvement of environmental awareness, photovoltaic energy has been widely used around the world. In recent years, the installed capacity of photovoltaic power generation has been continuously increased, and the amount of photovoltaic power generation has also increased rapidly. With the rapid development of photovoltaic power generation, practical problems of photovoltaic power generation have continued to emerge, one of which is the volatility of photovoltaic power generation. In order to improve the conversion efficiency of photovoltaic power generation and increase power revenue, most photovoltaic power generation units adopt the maximum power tracking control algorithm. The photovoltaic power generation power is closely related to the light intensity. Therefore, it is very easy to be affected by factors such as changes in sunlight intensity, seasonal changes or cloud cover, and power fluctuations occur. Fluctuating power injection into the power grid will cause instability in the frequency and voltage of the power grid, thereby affecting the operational stability of the power grid. In addition, photovoltaic power generation has an anti-peak characteristic, that is, when the light intensity is high during the day, the photovoltaic power generation is large but the load in the power grid is small, while at night the load in the power grid is large and the demand for power generation is high, but photovoltaic power generation does not work at night. The anti-peak characteristic has led to the phenomenon of "abandoning light" in various places, which has seriously restricted the development of photovoltaic power generation.

[0003] Another problem with photovoltaic power generation is that traditional grid-connected photovoltaic power generation cannot participate in the dynamic regulation of the power grid. This impact is not obvious when the proportion of photovoltaic power generation capacity is low. With the development of photovoltaic power generation and the withdrawal of traditional thermal power units, the impact of grid-connected photovoltaic power generation on the stability of the power grid can no longer be ignored. Studies have shown that the connection of a high proportion of grid-connected new energy units has a negative impact on the power grid dynamics, power quality, frequency control, voltage regulation and other control and operation issues. The grid-connected control strategy can make photovoltaic power generation show voltage source characteristics, which can enable photovoltaic power generation to operate stably in a weak power grid.

[0004] In the grid-connected photovoltaic and energy storage power generation system, the grid-connected grid-connected converter essentially controls the output power of the converter. Therefore, when the power direction is different, the grid-connected grid-connected converter will exhibit different dynamic characteristics, which will affect the parameter setting of the grid-connected photovoltaic and energy storage power generation system. Summary of the invention

[0005] In view of the shortcomings existing in the prior art, the present invention provides a method for impedance reshaping of a grid-type integrated photovoltaic and storage power generation system, which is used to solve the problem that the grid-type grid-connected converter will exhibit different dynamic characteristics when the power direction is different, thereby affecting the parameter setting of the grid-type integrated photovoltaic and storage power generation system.

[0006] The present invention provides a method for reshaping impedance of a grid-type photovoltaic-storage integrated power generation system, comprising the following steps:

[0007] Step S101, obtain the module information of the grid-type photovoltaic storage integrated power generation system, obtain the power direction judgment module and the impedance reshaping control module, collect the AC side three-phase voltage of the grid-type grid-connected converter in the grid-type photovoltaic storage integrated power generation system u pabc , three-phase current i abc And DC side voltage u dc ;

[0008] Step S102: collect the u pabc and i abc Input to the power direction judgment module;

[0009] Step S103: collect the DC side voltage u dc Input to the impedance reshaping control module;

[0010] Step S104: the power direction determination module determines the power direction according to the collected three-phase voltage on the AC side. u pabc And three-phase current i abc , calculate the active power of the grid-connected converter, the active power of the grid-connected converter includes positive active power and negative active power, and judge whether the impedance reshaping control module intervenes according to the positive and negative active power. If the active power is positive, the impedance reshaping control module intervenes, and if the active power is negative, the impedance reshaping control module does not intervene;

[0011] Step S105: when the impedance reshaping control module intervenes, the DC side voltage of the grid-connected converter in the grid-connected photovoltaic storage integrated power generation system is collected. u dc , the collected DC side voltage u dc The voltage difference is compared with the preset DC voltage reference value to obtain the voltage difference, which is amplified or reduced by a preset compensation coefficient to obtain the active power compensation value, and the impedance characteristics of the grid-connected converter are reshaped according to the active power compensation value.

[0012] Furthermore, the impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system of the present invention, step S101, comprises:

[0013] Initialize the grid-type photovoltaic storage integrated power generation system, identify the working status of the power direction judgment module and the impedance reshaping control module, and obtain information of the power direction judgment module and the impedance reshaping control module in working state;

[0014] Use voltage sensors to collect three-phase voltage from the AC side of the grid-connected converter u pabc ;

[0015] Use current sensors to collect three-phase current from the AC side of the grid-connected converter i abc ;

[0016] On the DC side of the grid-connected converter, a voltage sensor is used to collect the DC side voltage. u dc .

[0017] Furthermore, the impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system of the present invention, step S102 comprises:

[0018] The collected three-phase voltage u pabc , three-phase current i abc And DC side voltage u dc Preprocessing is performed, and the preprocessed three-phase voltage u pabc1 and three-phase current i abc1 Perform a data format check to check whether the data format meets the input requirements of the power direction judgment module. The data format check includes the number of data bits and the data type. If the check result shows that the data format does not meet the input requirements of the power direction judgment module, the data that does not meet the input requirements of the power direction judgment module is converted, and the converted data is used to replace the data that does not meet the input requirements of the power direction judgment module to obtain the three-phase voltage after the conversion. u pabc1 and three-phase current i abc1 ;

[0019] The three-phase voltage after conversion u pabc1 and three-phase current i abc1 The data is transmitted to the power direction determination module through the data channel inside the system;

[0020] Power direction judgment module initialization:

[0021] The power direction determination module receives the converted three-phase voltageu pabc1 and three-phase current i abc1 data;

[0022] The power direction judgment module uses a preset algorithm to convert the three-phase voltage format. u pabc1 and three-phase current i abc1 The data is calculated to obtain the active power of the grid-connected converter;

[0023] The power direction judgment module judges the power direction of the grid-connected converter according to the positive and negative values ​​of the active power of the grid-connected converter.

[0024] Furthermore, the impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system of the present invention, step S103, comprises:

[0025] Collecting DC voltage from the DC side of the grid-connected converter u dc , the collected DC side voltage u dc Perform calibration and check the DC side voltage u dc Check whether the number of data bits and data types meet the input requirements of the impedance reshaping control module. If the DC side voltage is checked u dc If the number of data bits and data types do not meet the input requirements of the impedance reshaping control module, the DC side voltage u dc Perform data format conversion to obtain the converted DC side voltage u dc1；

[0026] The pre-processed DC voltage u dc1 The data is transmitted to the impedance reshaping control module through the data channel inside the system;

[0027] The impedance reshaping control module receives the DC side voltage transmitted u dc1 The data is stored in the internal memory of the module. The impedance reshaping control module adjusts the DC side voltage according to the preset algorithm. u dc1 The data is calculated to obtain the active power compensation value control parameters.

[0028] Furthermore, the impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system of the present invention, step S104, comprises:

[0029] The power direction judgment module receives the collected three-phase voltage on the AC side u pabc and three-phase current i abc , for three-phase voltage u pabc and three-phase current i abc To perform coordinate transformation, usually Park transformation is used to transform the three-phase voltage u pabc and three-phase current i abc Transform from a three-phase stationary coordinate system to a two-phase rotating coordinate system. The three-phase stationary coordinate system is the abc coordinate system, and the two-phase rotating coordinate system is the dq coordinate system.

[0030] In the dq coordinate system, the active power of the grid-connected converter is calculated according to the preset active power calculation formula;

[0031] According to the positive and negative values ​​of the calculated active power, the power direction of the grid-connected converter is determined;

[0032] Outputting the judgment result to the impedance reshaping control module as a basis for the control module to intervene;

[0033] If the active power is positive, the impedance reshaping control module intervenes;

[0034] If the active power is negative, the impedance reshaping control module does not intervene.

[0035] Furthermore, the impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system of the present invention, step S105, comprises:

[0036] Collect the DC side voltage again from the DC side of the grid-connected converter u dc , obtain the preset DC voltage reference value, check the collected DC side voltage u dc The data type and data accuracy of the preset DC voltage reference value are consistent, and the collected DC side voltage u dc Compare the DC voltage reference value point by point to calculate the DC side voltage u dc The difference between the preset DC voltage reference, that is, the voltage difference Δ udc =The collected DC voltage - the preset DC voltage reference value.

[0037] Furthermore, the impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system of the present invention, step S105, comprises:

[0038] According to the system preset threshold range, check the voltage difference Δ udc Is it within a reasonable range?

[0039] If the voltage difference Δ udc If it exceeds the reasonable range, exception handling will be performed, including recording error logs and issuing alarm signals;

[0040] If the voltage difference Δ udc If the voltage difference is within a reasonable range, then verify that udc Is the data format consistent with the system preset data type? If the voltage difference Δ udc If the data format does not meet the requirements, the voltage difference Δ udc Perform format conversion to obtain the voltage difference Δ after verification udc .

[0041] The present invention provides an impedance reshaping method for a grid-type photovoltaic-storage integrated power generation system. The method can enable the grid-connected grid-connected converter in the grid-type photovoltaic-storage integrated power generation system to exhibit similar power output characteristics in different power directions, thereby simplifying the parameter setting difficulty of the grid-type photovoltaic-storage integrated power generation system and improving the stability of the grid-type photovoltaic-storage integrated power generation system.

[0042] The present invention calculates the three-phase voltage by the following formula: u pabc and three-phase current i abc Perform Park transform:

[0043]

[0044] The present invention calculates the active power of the grid-connected converter by the following formula:

[0045]

[0046] The impedance reshaping control module of the present invention is implemented by the following formula:

[0047]

[0048] in is the active power compensation value, is the compensation coefficient, is the DC voltage reference value.

[0049] The first output end of the impedance reshaping control module is connected to the second input end of the power direction judgment module, and the first output end of the power direction judgment module is added to the power setting value in the networking control strategy.

[0050] The advantages and beneficial effects of the present invention are:

[0051] The present invention uses an impedance reshaping method to make the grid-connected converter in the grid-connected photovoltaic and energy storage integrated power generation system show more stable impedance characteristics in the positive power direction, thereby improving the stability of the entire power generation system in the positive power direction. This helps to reduce power fluctuations and enhance the system's ability to cope with external interference.

[0052] Since the present invention reshapes the impedance characteristics of the grid-connected converter without changing the main structure of the grid-connected control, the grid-connected photovoltaic and storage integrated power generation system exhibits similar power output characteristics in different power directions. This greatly simplifies the difficulty of parameter setting of the system and reduces the technical requirements for operators.

[0053] By reshaping the impedance, the present invention enhances the adaptability of the grid-connected photovoltaic and storage integrated power generation system to the grid environment, enabling it to operate stably under a wider range of grid conditions. This improves the robustness of the system and reduces the risk of system instability caused by changes in the grid environment.

[0054] The present invention proposes an effective solution to the problems of volatility and reverse peak of photovoltaic power generation, making photovoltaic power generation more reliable and stable, which helps to promote the widespread application of photovoltaic power generation and the development of the renewable energy industry.

[0055] By improving system stability and robustness, the present invention reduces downtime and maintenance costs caused by system instability. At the same time, by simplifying the difficulty of parameter setting and reducing operation and maintenance costs, the economic benefits of the entire grid-type photovoltaic storage integrated power generation system are improved.

[0056] In summary, the present invention significantly improves the stability, robustness and economic benefits of the grid-type integrated photovoltaic and storage power generation system through the impedance reshaping method, providing strong technical support for the widespread application of photovoltaic power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a structural schematic diagram of a grid-type photovoltaic and storage integrated power generation system;

[0058] Figure 2 It is a schematic diagram of the control structure of the network control strategy;

[0059] Figure 3 It is the Bode diagram of the DC side impedance of the grid-connected converter before improvement;

[0060] Figure 4 This is the power curve of the grid-connected photovoltaic and storage integrated power generation system before improvement;

[0061] Figure 5 It is a structural schematic diagram of an impedance reshaping method for a grid-type photovoltaic-storage integrated power generation system;

[0062] Figure 6 It is the Bode diagram of the DC side impedance of the grid-connected converter in the positive power direction after improvement;

[0063] Figure 7 This is the power curve of the improved grid-connected photovoltaic and storage integrated power generation system in the positive power direction. DETAILED DESCRIPTION

[0064] An embodiment of the present invention is further described below with reference to the accompanying drawings.

[0065] like Figure 1 The schematic diagram of the structure of the grid-connected photovoltaic and energy storage integrated power generation system is shown. In order to ensure the stable operation of the system, the photovoltaic DC / DC converter adopts the maximum power point tracking control strategy to improve the conversion efficiency of photovoltaic power generation. The energy storage DC / DC converter adopts constant DC voltage control to ensure the voltage stability of the DC bus. The photovoltaic grid-connected converter adopts a grid-connected control strategy. The grid-connected control strategy in the present invention refers to virtual synchronous generator control.

[0066] Figure 1 middle is the grid voltage, is the grid current, is the bridge arm voltage of the grid-connected converter, is the DC side current of the grid-connected converter, is the DC voltage of the grid-connected converter, , are the equivalent inductance and equivalent resistance of the power grid respectively, , , They are the grid-connected converter filter capacitance, filter inductance and filter parasitic resistance respectively. is the angular frequency.

[0067] according to Figure 1 As shown, the dq coordinate system small signal model equation of the electrical part of the grid-type converter can be written.

[0068]

[0069]

[0070]

[0071]

[0072] in:

[0073]

[0074]

[0075]

[0076] Among them, the superscript Represents the component of the variable in the VSG coordinate system, with the superscript Represents the component of the variable in the phase-locked loop coordinate system, with the superscript Represents the component of the variable in the system coordinate system. Symbol Represents the small signal disturbance of the variable at the steady-state operating point, with the subscript Represents the value of the variable at the steady-state operating point.

[0077] like Figure 2 As shown in the figure, the control structure diagram of the network control strategy is as follows: Figure 2 The small signal model equation for the grid-based control strategy can be written.

[0078]

[0079]

[0080] (

[0081]

[0082] in:

[0083]

[0084]

[0085]

[0086]

[0087] in, is the active loop output angle, Active loop output angular frequency, and are the moment of inertia coefficient and damping coefficient, respectively. is the frequency droop coefficient, is the phase-locked loop output angular frequency, It is the reference value of reactive loop output voltage. is the voltage droop coefficient, , They are the proportional coefficient and integral coefficient of the reactive loop PI controller, is the duty cycle, Laplace operator.

[0088] The relationship between the system coordinate system and the VSG coordinate system is as follows:

[0089]

[0090] Where is a variable, when When it is smaller, it can be considered , . Then we can get:

[0091]

[0092]

[0093] Similarly, the relationship between the system coordinate system and the phase-locked loop coordinate system is:

[0094]

[0095] The small signal model equation of the control part and the small signal model equation of the electrical part of the grid-connected converter can be combined to obtain:

[0096]

[0097] in:

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112] The active power of the grid-connected converter is set to 1p.u. and -1p.u. respectively, and we can get The Bode plot is as follows Figure 3 As shown. It can be seen that under the same power value and different power directions, The amplitude-frequency characteristic curves of The phase-frequency curve shows the opposite impedance characteristics. When the power direction is negative, It exhibits positive impedance characteristics in the low frequency band. When the power direction is positive, It exhibits negative impedance characteristics. This opposite impedance characteristic makes the grid-type converter exhibit different output performance when the power direction is different.

[0113] Figure 4 This is the power curve of the grid-type photovoltaic and storage integrated power generation system before improvement. It can be seen that when the power change range is the same, the output power performance of the grid-type photovoltaic and storage integrated power generation system is completely different. When the power direction of the grid-type converter is in the negative direction, the grid-type photovoltaic and storage integrated power generation system will quickly stabilize after the power change. When the power direction of the grid-type converter is in the positive direction, the grid-type photovoltaic and storage integrated power generation system will produce continuous power oscillations after the power change. The oscillation time is about 1.5s and the power overshoot is larger. This shows that the stability of the grid-type photovoltaic and storage integrated power generation system is different under different power directions, which affects the parameter setting and robustness of the grid-type photovoltaic and storage integrated power generation system.

[0114] Figure 5 The present invention is a schematic diagram of the structure of the impedance reshaping method of the grid-type integrated photovoltaic and storage power generation system. The collected upabc and iabc are input to the first input end of the power direction judgment module. The power direction judgment module calculates the active power of the grid-type grid-connected converter according to the collected upabc and iabc. The impedance reshaping control module is judged whether to intervene according to the positive and negative of the active power. If the active power is positive, the impedance reshaping control module intervenes. If the active power is negative, the impedance reshaping control module does not intervene. The first output end of the impedance reshaping control module is connected to the second input end of the power direction judgment module, and the first output end of the power direction judgment module is added to the power setting value in the grid-type control strategy.

[0115] In the impedance reshaping control strategy, the DC side voltage udc and the DC voltage reference value of the grid-connected converter in the grid-connected photovoltaic storage integrated power generation system are collected. The result is input into the compensation coefficient The active power compensation value is obtained .

[0116] The power direction determination module calculates the active power according to the following equation.

[0117]

[0118]

[0119]

[0120] Figure 6 This is the Bode diagram of the DC side impedance of the grid-connected converter under the improved power positive direction. It can be seen that after the impedance is reshaped, when the power direction is in the positive direction It exhibits positive impedance characteristics in the low-frequency band, which improves the stability of the grid-building type photovoltaic and storage integrated power generation system, making the grid-building type photovoltaic and storage integrated power generation system also have good stability in the positive power direction.

[0121] Figure 7 This is the power curve of the improved grid-type photovoltaic and storage integrated power generation system in the positive power direction. It can be seen that after the impedance reshaping, the grid-type photovoltaic and storage integrated power generation system will quickly stabilize after the power changes in the positive power direction. This shows that the stability of the grid-type photovoltaic and storage integrated power generation system has been improved after the impedance reshaping.

[0122] In the embodiment of the present invention, the method of the present invention can reshape the impedance characteristics of the grid-connected converter in the grid-connected photovoltaic and storage integrated power generation system without changing the main control structure of the grid-connected control. The stability of the grid-connected photovoltaic and storage integrated power generation system in the positive power direction is improved, thereby simplifying the difficulty of parameter setting of the grid-connected photovoltaic and storage integrated power generation system and improving the robustness of the grid-connected photovoltaic and storage integrated power generation system.

[0123] The present invention solves the problem that when the power direction is different, the grid-connected converter exhibits different dynamic characteristics, thereby affecting the parameter setting of the grid-connected photovoltaic storage integrated power generation system through the following technical solutions:

[0124] The present invention collects the three-phase voltage and three-phase current on the AC side of the grid-connected converter and uses this information to calculate the active power. The current power direction is determined according to the positive or negative active power. When the active power is positive (i.e., the power direction is positive), the impedance reshaping control module intervenes to reshape the impedance characteristics of the grid-connected converter. When the active power is negative, the impedance reshaping control module does not intervene and maintains the original control strategy.

[0125] The impedance reshaping control module collects the DC side voltage and compares it with the preset DC voltage reference value to calculate the voltage difference. This voltage difference is amplified or reduced by the preset compensation coefficient to obtain the active power compensation value. The active power compensation value is used to adjust the control parameters of the grid-connected converter to reshape its impedance characteristics. This enables the grid-connected converter to exhibit more stable impedance characteristics and reduce power fluctuations when the power is in the positive direction.

[0126] In the process of reshaping the impedance characteristics of the grid-connected converter, the present invention does not change the main control structure of the grid-connected control, which ensures the overall stability and reliability of the system and simplifies the difficulty of technical implementation.

[0127] Through impedance reshaping, the present invention enables the grid-type photovoltaic storage integrated power generation system to exhibit similar power output characteristics in both the positive and negative directions. This improves the robustness of the system, enabling it to better adapt to different power grid environments and operating conditions. At the same time, since the system exhibits similar characteristics in both power directions, the difficulty of parameter setting is also simplified. Operators do not need to make complex parameter adjustments for different power directions, reducing operation and maintenance costs and technical requirements.

[0128] In summary, the present invention effectively solves the problem of the influence of the dynamic characteristics of the grid-connected converter when the power direction is different on the system parameter setting through technical means such as power direction judgment, impedance reshaping control strategy and keeping the main structure of the grid-connected control unchanged.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for impedance reshaping of a grid-type photovoltaic-storage integrated power generation system, comprising the following steps: Step S101, obtain the module information of the grid-type photovoltaic storage integrated power generation system, obtain the power direction judgment module and the impedance reshaping control module, collect the AC side three-phase voltage of the grid-type grid-connected converter in the grid-type photovoltaic storage integrated power generation system u pabc , three-phase current i abc And DC side voltage u dc ; Step S102: collect the u pabc and i abc Input to the power direction judgment module; Step S103: collect the DC side voltage u dc Input to the impedance reshaping control module; Step S104: the power direction determination module determines the power direction according to the collected three-phase voltage on the AC side. u pabc And three-phase current i abc , calculate the active power of the grid-connected converter, the active power of the grid-connected converter includes positive active power and negative active power, and judge whether the impedance reshaping control module intervenes according to the positive and negative active power. If the active power is positive, the impedance reshaping control module intervenes, and if the active power is negative, the impedance reshaping control module does not intervene; Step S105: when the impedance reshaping control module intervenes, the DC side voltage of the grid-connected converter in the grid-connected photovoltaic storage integrated power generation system is collected. u dc , the collected DC side voltage u dc The voltage difference is compared with the preset DC voltage reference value to obtain the voltage difference, which is amplified or reduced by a preset compensation coefficient to obtain the active power compensation value, and the impedance characteristics of the grid-connected converter are reshaped according to the active power compensation value.

2. The impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system according to claim 1 is characterized in that: The step S101 includes: Initialize the grid-type photovoltaic storage integrated power generation system, identify the working status of the power direction judgment module and the impedance reshaping control module, and obtain information of the power direction judgment module and the impedance reshaping control module in working state; Use voltage sensors to collect three-phase voltage from the AC side of the grid-connected converter u pabc ; Use current sensors to collect three-phase current from the AC side of the grid-connected converter i abc ; On the DC side of the grid-connected converter, a voltage sensor is used to collect the DC side voltage. u dc .

3. The impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system according to claim 1 is characterized in that: The step S102 includes: The collected three-phase voltage u pabc , three-phase current i abc And DC side voltage u dc Preprocessing is performed and the preprocessed three-phase voltage u pabc1 and three-phase current i abc1 Perform a data format check to check whether the data format meets the input requirements of the power direction judgment module. The data format check includes the number of data bits and the data type. If the check result shows that the data format does not meet the input requirements of the power direction judgment module, the data that does not meet the input requirements of the power direction judgment module is converted, and the converted data is used to replace the data that does not meet the input requirements of the power direction judgment module to obtain the three-phase voltage after the conversion. u pabc1 and three-phase current i abc1 ; The three-phase voltage after conversion u pabc1 and three-phase current i abc1 The data is transmitted to the power direction determination module through the data channel inside the system; Power direction judgment module initialization: The power direction determination module receives the converted three-phase voltage u pabc1 and three-phase current i abc1 data; The power direction judgment module uses a preset algorithm to convert the three-phase voltage format. u pabc1 and three-phase current i abc1 The data is calculated to obtain the active power of the grid-connected converter; The power direction judgment module judges the power direction of the grid-connected converter according to the positive and negative values ​​of the active power of the grid-connected converter.

4. The impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system according to claim 1 is characterized in that: The step S103 includes: Collecting DC voltage from the DC side of the grid-connected converter u dc , the collected DC side voltage u dc Perform calibration and check the DC side voltage u dc Check whether the number of data bits and data types meet the input requirements of the impedance reshaping control module. If the DC side voltage is checked u dc If the number of data bits and data types do not meet the input requirements of the impedance reshaping control module, the DC side voltage u dc Perform data format conversion to obtain the converted DC side voltage u dc1； The pre-processed DC side voltage u dc1 The data is transmitted to the impedance reshaping control module through the data channel inside the system; The impedance reshaping control module receives the DC side voltage transmitted u dc1 The data is stored in the internal memory of the module. The impedance reshaping control module adjusts the DC side voltage according to the preset algorithm. u dc1 The data is calculated to obtain the active power compensation value control parameters.

5. The impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system according to claim 1 is characterized in that: The step S104 includes: The power direction judgment module receives the collected three-phase voltage on the AC side u pabc and three-phase current i abc , for three-phase voltage u pabc and three-phase current i abc To perform coordinate transformation, usually Park transformation is used to transform the three-phase voltage u pabc and three-phase current i abc Transform from a three-phase stationary coordinate system to a two-phase rotating coordinate system. The three-phase stationary coordinate system is the abc coordinate system, and the two-phase rotating coordinate system is the dq coordinate system. In the dq coordinate system, the active power of the grid-connected converter is calculated according to the preset active power calculation formula; According to the positive and negative values ​​of the calculated active power, the power direction of the grid-connected converter is determined; Outputting the judgment result to the impedance reshaping control module as a basis for the control module to intervene; If the active power is positive, the impedance reshaping control module intervenes; If the active power is negative, the impedance reshaping control module does not intervene.

6. The impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system according to claim 1 is characterized in that: The step S105 includes: Collect the DC side voltage again from the DC side of the grid-connected converter u dc , obtain the preset DC voltage reference value, check the collected DC side voltage u dc The data type and data accuracy of the preset DC voltage reference value are consistent, and the collected DC side voltage u dc Compare the DC voltage reference value point by point to calculate the DC side voltage u dc The difference between the preset DC voltage reference, that is, the voltage difference Δ udc =The collected DC voltage - the preset DC voltage reference value.

7. The impedance reshaping method of the grid-type photovoltaic-storage integrated power generation system according to claim 6 is characterized in that: The step S105 includes: According to the system preset threshold range, check the voltage difference Δ udc Is it within a reasonable range? If the voltage difference Δ udc If it exceeds the reasonable range, exception handling will be performed, including recording error logs and issuing alarm signals; If the voltage difference Δ udc If the voltage difference is within a reasonable range, then verify that udc Is the data format consistent with the system preset data type? If the voltage difference Δ udc If the data format does not meet the requirements, the voltage difference Δ udc Perform format conversion to obtain the voltage difference Δ after verification udc .

Images