A flexible power supply system with efficient utilization of distributed photovoltaic storage

Abstract

The present invention discloses a flexible power supply system for efficient utilization of distributed photovoltaic storage, including a distributed photovoltaic power generation module, a distributed photovoltaic energy storage module, a frequency converter, a public power grid, a maximum power point tracking module, a maximum power point analysis module and a motor load; a distributed photovoltaic power generation module, used to directly convert solar energy into electrical energy through photovoltaic components; a distributed photovoltaic energy storage module, used to convert the distributed photovoltaic power generation module into alternating current through a frequency converter; a frequency converter, used to control alternating current by changing the frequency of the motor working power supply; a public power grid, used to transmit alternating current; a high power point tracking module, used to track the maximum power point of distributed photovoltaic power generation; a maximum power point analysis module, used to analyze the maximum power point of distributed photovoltaic power generation. After the incremental conductance method of the present invention reaches the optimal power point, when the conditions meet the conditions of the optimal power point, the optimal point will remain stable in the corresponding state.

Description

Technical Field

[0001] The present invention relates to the field of flexible power supply technology, and in particular to a flexible power supply system for efficient utilization of distributed photovoltaic storage. Background Art

[0002] Solar energy is a very rich radiation energy. It is cheap, pollution-free, inexhaustible, and can be used flexibly by humans. This is particularly important for the current attention paid by humans to environmental pollution.

[0003] At present, distributed photovoltaic panels are devices that directly convert solar energy into electrical energy. They are generally composed of semiconductor materials such as silicon, potassium arsenide, and selenium indium copper. The common distributed photovoltaic panels are made of silicon distributed photovoltaic panels. "Silicon" is one of the most abundant materials on the earth. The production process of silicon distributed photovoltaic panels can be roughly divided into five steps: purification, rod drawing, slicing, battery making, and packaging. There are currently three main types of silicon distributed photovoltaic panels that have been developed into commercialization, namely single-crystal silicon, polycrystalline silicon, and amorphous silicon distributed photovoltaic panels. The single-crystal silicon distributed photovoltaic panels use the same quality as the materials used in the semiconductor industry, resulting in a relatively expensive material cost. The efficiency of polycrystalline silicon distributed photovoltaic panels is generally lower than that of single-crystal silicon, but it can be produced by casting, so its cost is also lower than that of single-crystal silicon. As for amorphous silicon, its application prospects in high-power solar power generation are slim. In comparison, polycrystalline silicon distributed photovoltaic panels will be more developed in the future.

[0004] At present, with the development of solar photovoltaic industry, there are many methods for tracking the best power point, including offline and online. The offline method is to understand the various parameters of solar photovoltaic cells in detail in advance and measure the various values, including junction temperature, light intensity, open circuit voltage, open circuit current, ambient temperature, etc. The online method is to first calculate the actual output power of the solar photovoltaic cell, compare it with the current online value, and adjust the output signal to achieve the best power point.

[0005] Currently, no effective solution has been proposed for the problems in the related technologies. Summary of the invention

[0006] In view of the problems in the related technology, the present invention proposes a flexible power supply system for efficient utilization of distributed photovoltaic storage to overcome the above-mentioned technical problems existing in the existing related technology.

[0007] To this end, the specific technical solution adopted by the present invention is as follows:

[0008] A flexible power supply system for efficient utilization of distributed photovoltaic energy storage, comprising a distributed photovoltaic power generation module, a distributed photovoltaic energy storage module, a frequency converter, a public power grid, a maximum power point tracking module, a maximum power point analysis module and a motor load;

[0009] The distributed photovoltaic power generation module, the distributed photovoltaic energy storage module, the inverter, the motor load and the public power grid are connected in sequence;

[0010] The public power grid is connected to the maximum power point tracking module and the maximum power point analysis module;

[0011] The distributed photovoltaic power generation module is used to directly convert solar energy into electrical energy through photovoltaic components;

[0012] The distributed photovoltaic energy storage module is used to convert the distributed photovoltaic power generation module into alternating current through the inverter and store the alternating current in the public power grid;

[0013] The frequency converter is used to control the AC power by changing the frequency of the motor's working power supply;

[0014] The public power grid is used to transmit alternating current;

[0015] The high power point tracking module is used to track the maximum power point of distributed photovoltaic power generation;

[0016] The maximum power point analysis module is used to analyze the maximum power point of distributed photovoltaic power generation and reduce energy loss during operation;

[0017] The motor load is used to work according to the received alternating current sent by the frequency converter.

[0018] Further, the frequency converter includes a first bidirectional converter, an inverter and a DC bus, and the first bidirectional converter and the inverter are connected via the DC bus;

[0019] The first bidirectional converter is connected to the public grid and is used to convert the AC power received from the public grid into DC power and output it to the DC bus, and convert the DC power sent by the DC bus into AC power and output it to the public grid;

[0020] The inverter is connected to the motor load and is used for converting the direct current sent by the direct current bus into alternating current and outputting it to the motor load.

[0021] Furthermore, the high power point tracking module includes a control module, a PWM generation module, an A / D conversion module, a sampling adjustment circuit module, and a driving circuit module;

[0022] Among them, the control module mainly operates the data of the A / D conversion module, finds the maximum power point, and controls the output duty cycle of the PWM module;

[0023] The control module, PWM generation module and A / D conversion module can be controlled by a single chip microcomputer and together with other peripheral hardware form a solar energy conversion device.

[0024] Furthermore, the method for tracking the maximum power point of distributed photovoltaic power generation also includes the following steps:

[0025] When light shines on the distributed photovoltaic panels, electron-hole pairs are generated. The carriers generated near the internal junction of the semiconductor are not recombined and reach the space charge region. Attracted by the strong electric field, the electrons flow into the N region and the holes flow into the P region.

[0026] If the external circuit is short-circuited, a photocurrent proportional to the incident light flux will flow in the external circuit;

[0027] When both ends of the PN junction are open, electrons and holes flow into the N region and the P region respectively, causing the Fermi level of the N region to be higher than that of the P region, and a potential difference is generated between the two Fermi levels.

[0028] Measure the vertical potential difference and determine the maximum power point.

[0029] Furthermore, the distributed photovoltaic power generation panels are divided into plastic shell filled resin type, glass shell type, and metal base type according to their structure;

[0030] Wherein, the plastic shell is filled with resin type, and a transparent plastic material with good weather resistance is used for the outer wall, and the distributed photovoltaic cell pieces are filled with water-resistant transparent resin;

[0031] The glass shell type uses tempered glass for the main part of the outer wall, the outer periphery is fixed with a rust-proof metal frame, and the interior is filled with water-resistant resin;

[0032] The metal base type is used in a metal base that has been rust-proofed and a shell formed by a glass-reinforced plastic laminate, and is equipped with a pre-connected distributed photovoltaic cell element group and a structure filled with a water-resistant transparent resin. In order to prevent dust impurities in the air from adhering to the surface of the transparent resin, a layer of plastic material with good slip performance is applied.

[0033] Furthermore, the step of measuring the vertical potential difference and determining the maximum power point further comprises the following steps:

[0034] Calculate the volt-ampere characteristics of distributed photovoltaic panels;

[0035] According to the power of distributed photovoltaic panels, the voltage is derived and the maximum power point is obtained.

[0036] Furthermore, the calculation formula of the maximum power point is as follows:

[0037]

[0038] make but

[0039] Let P s is the panel power. Since power is equal to the product of current and voltage, that is:

[0040]

[0041] Taking the derivative of the voltage at both ends yields:

[0042] Maximum Power Point:

[0043] In the formula, in the formula, i s is the panel current, e s is the panel voltage, I ph is the short-circuit current I of the distributed photovoltaic panel o is the reverse saturation current of the diode, q is the electron charge, K is the Boltzmann constant, T is the absolute temperature, and d is the differential.

[0044] Furthermore, the method for analyzing the maximum power point of distributed photovoltaic power generation and reducing energy loss during operation also includes the following steps:

[0045] The incremental conductance method is used to track the optimal power point, and the output voltage form of the solar photovoltaic cell array is adjusted to achieve the purpose of maximum power tracking;

[0046] The maximum power point of distributed photovoltaic power generation is analyzed based on the perturbation observation method, and the distributed photovoltaic power generation cells are configured to a voltage near the maximum output power point according to the requirements of the inverter DC side voltage.

[0047] Furthermore, the incremental conductance method construction includes the following steps:

[0048] Construct the PV curve of the distributed photovoltaic power generation battery array. At the maximum power point, the derivative of power to voltage is zero;

[0049] When the output power is not at the maximum power point, the tracking direction of the control algorithm can be determined according to the positive and negative values ​​of dP / dV, that is, at the maximum power point:

[0050] When dP / dV = 0 at the maximum power point;

[0051] When dP / dV>0 is on the left side of the maximum power point;

[0052] When dP / dV<0, it is on the right side of the maximum power point;

[0053] The voltage and current of the photovoltaic array are expressed as follows:

[0054] dP / dV=d(V×I) / dV=I+V×dI / dV

[0055]

[0056] When V<V max hour,

[0057] V>V max hour,

[0058] V=V max hour,

[0059] In the formula, d is the differential, V is the voltage, I is the current, V max is the maximum voltage;

[0060] The optimum power tracking point is achieved by changing the operating point voltage according to the relationship between dP / dV and I / V.

[0061] Furthermore, the construction of the perturbation and observation method includes the following steps:

[0062] Increase or decrease the output voltage of the distributed photovoltaic panel array within a fixed cycle, measure the direction of power change at the output point, and determine and adjust the control signal for the next cycle;

[0063] The output power feedback method is adopted to obtain the output voltage and current of the distributed photovoltaic panel array through the current transformer and the voltage transformer, and the load power value is obtained through calculation;

[0064] Under stable working conditions, the perturbation and observation method will make optimal adjustments at the best power point according to the numerical changes in the load power value.

[0065] The beneficial effects of the present invention are:

[0066] 1. The present invention connects the distributed power source, the public power grid and the motor load to the inverter respectively, so that the motor load can receive the power from the distributed power source through the inverter and work normally even when the public power grid is unavailable.

[0067] 2. The disturbance observation method of the present invention is simple and easy, requires fewer measurement parameters, and is simple to implement. From the above description and analysis, it can be seen that it is only necessary to collect the load voltage of the photovoltaic cell array and the load battery to calculate the total power and compare it with the previous power. According to the comparison result, the direction of the next adjustment can be determined.

[0068] 3. The incremental conductance method of the present invention will not produce oscillation after reaching the optimal power point; when the conditions meet the optimal power point conditions, the optimal point will remain stable in the corresponding state; the incremental conductance method will not malfunction when the environmental conditions change rapidly, and has good applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0070] Figure 1 This is a principle block diagram of a flexible power supply system for efficient utilization of distributed photovoltaic storage according to an embodiment of the present invention;

[0071] Figure 2 It is a flow chart of an incremental conduction method in an embodiment of a flexible power supply system for efficient utilization of distributed photovoltaic storage according to an embodiment of the present invention;

[0072] Figure 3 It is a flow chart of a disturbance observation method in an embodiment of a flexible power supply system for efficient utilization of distributed photovoltaic storage according to an embodiment of the present invention.

[0073] In the figure:

[0074] 1. Distributed photovoltaic power generation module; 2. Distributed photovoltaic energy storage module; 3. Frequency converter; 31. First bidirectional converter; 32. Inverter; 33. DC bus; 4. Public power grid; 5. Maximum power point tracking module; 51. Control module; 52. PWM generation module; 53. A / D conversion module; 54. Sampling adjustment circuit module; 55. Drive circuit module; 6. Maximum power point analysis module; 7. Motor load. DETAILED DESCRIPTION

[0075] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention and are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in the field should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0076] According to an embodiment of the present invention, a flexible power supply system for efficient utilization of distributed photovoltaic storage is provided.

[0077] The present invention is further described with reference to the accompanying drawings and specific embodiments. Figure 1 As shown, the flexible power supply system for efficient utilization of distributed photovoltaic energy storage according to an embodiment of the present invention includes a distributed photovoltaic power generation module 1, a distributed photovoltaic energy storage module 2, a frequency converter 3, a public power grid 4, a maximum power point tracking module 5, a maximum power point analysis module 6 and a motor load 7;

[0078] The distributed photovoltaic power generation module 1, the distributed photovoltaic energy storage module 2, the inverter 3, the motor load 7 and the public power grid 4 are connected in sequence;

[0079] The public power grid 4 is connected to the maximum power point tracking module 5 and the maximum power point analysis module 6;

[0080] The distributed photovoltaic power generation module 1 is used to directly convert solar energy into electrical energy through photovoltaic components.

[0081] The distributed photovoltaic energy storage module 2 is used to convert the distributed photovoltaic power generation module into alternating current through the inverter, and store the alternating current in the public power grid.

[0082] The frequency converter 3 is used to control the AC power by changing the frequency of the motor working power supply;

[0083] In one embodiment, the frequency converter 3 includes a first bidirectional converter 31, an inverter 32 and a DC bus 33, wherein the first bidirectional converter 31 and the inverter 32 are connected via the DC bus 33;

[0084] The first bidirectional converter 31 is connected to the public grid 4, and is used to convert the AC power received from the public grid 4 into DC power and output it to the DC bus 33, and convert the DC power sent by the DC bus 33 into AC power and output it to the public grid 4;

[0085] The inverter 32 is connected to the motor load 7 and is used to convert the direct current sent by the direct current bus 33 into alternating current and output it to the motor load 7 .

[0086] The public power grid 4 is used to transmit alternating current;

[0087] The high power point tracking module 5 is used to track the maximum power point of distributed photovoltaic power generation;

[0088] In one embodiment, the high power point tracking module 5 includes a control module 51, a PWM generation module 52, an A / D conversion module 53, a sampling adjustment circuit module 54, and a driving circuit module 55;

[0089] The control module 51 mainly performs operations on the data of the A / D conversion module 53, finds the maximum power point, and controls the output duty cycle of the PWM module;

[0090] The control module 51, the PWM generation module 52, and the A / D conversion module 53 can be controlled by a single chip microcomputer, and together with other peripheral hardware, form a solar energy conversion device;

[0091] In one embodiment, the method for tracking the maximum power point of distributed photovoltaic power generation further includes the following steps:

[0092] When light shines on the distributed photovoltaic panels, electron-hole pairs are generated. The carriers generated near the internal junction of the semiconductor are not recombined and reach the space charge region. Attracted by the strong electric field, the electrons flow into the N region and the holes flow into the P region.

[0093] If the external circuit is short-circuited, a photocurrent proportional to the incident light flux will flow in the external circuit;

[0094] When both ends of the PN junction are open, electrons and holes flow into the N region and the P region respectively, causing the Fermi level of the N region to be higher than that of the P region, and a potential difference is generated between the two Fermi levels.

[0095] Measure the vertical potential difference and determine the maximum power point;

[0096] In one embodiment, the distributed photovoltaic power generation panel is divided into a plastic shell filled with resin type, a glass shell type, and a metal base type according to the structure;

[0097] Wherein, the plastic shell is filled with resin type, and a transparent plastic material with good weather resistance is used for the outer wall, and the distributed photovoltaic cell pieces are filled with water-resistant transparent resin;

[0098] The glass shell type uses tempered glass for the main part of the outer wall, the outer periphery is fixed with a rust-proof metal frame, and the interior is filled with water-resistant resin;

[0099] The metal base type is used in a metal base after rust prevention treatment and a shell formed by a glass-reinforced plastic laminate, and is equipped with a pre-connected distributed photovoltaic cell element group and filled with a water-resistant transparent resin structure. In order to prevent dust impurities in the air from adhering to the surface of the transparent resin, a layer of plastic material with slippery performance is applied;

[0100] In one embodiment, the step of measuring the vertical potential difference and determining the maximum power point further comprises the following steps:

[0101] Calculate the volt-ampere characteristics of distributed photovoltaic panels;

[0102] According to the power of distributed photovoltaic panels, the voltage is derived and the maximum power point is obtained;

[0103] In one embodiment, the maximum power point is calculated as follows:

[0104]

[0105] make but

[0106] Let P s is the panel power. Since power is equal to the product of current and voltage, that is:

[0107]

[0108] Taking the derivative of the voltage at both ends yields:

[0109] Maximum Power Point:

[0110] In the formula, in the formula, i s is the panel current, e s is the panel voltage, I ph is the short-circuit current I of the distributed photovoltaic panel o is the reverse saturation current of the diode, q is the electron charge, K is the Boltzmann constant, T is the absolute temperature, and d is the differential.

[0111] The maximum power point analysis module 6 is used to analyze the maximum power point of distributed photovoltaic power generation and reduce energy loss during operation;

[0112] In one embodiment, the method for analyzing the maximum power point of distributed photovoltaic power generation and reducing energy loss during operation further includes the following steps:

[0113] The incremental conductance method is used to track the optimal power point, and the output voltage form of the solar photovoltaic cell array is adjusted to achieve the purpose of maximum power tracking;

[0114] The maximum power point of distributed photovoltaic power generation is analyzed based on the perturbation observation method, and the distributed photovoltaic power generation cells are configured to have a voltage near the maximum output power point according to the requirements of the inverter DC side voltage;

[0115] In one embodiment, the incremental conductance method construction comprises the following steps:

[0116] Construct the PV curve of the distributed photovoltaic power generation battery array. At the maximum power point, the derivative of power to voltage is zero;

[0117] When the output power is not at the maximum power point, the tracking direction of the control algorithm can be determined according to the positive and negative values ​​of dP / dV, that is, at the maximum power point:

[0118] When dP / dV = 0 at the maximum power point;

[0119] When dP / dV>0 is on the left side of the maximum power point;

[0120] When dP / dV<0, it is on the right side of the maximum power point;

[0121] The voltage and current of the photovoltaic array are expressed as follows:

[0122] dP / dV=d(V×I) / dV=I+V×dI / dV

[0123]

[0124] When V<V max hour,

[0125] V>V max hour,

[0126] V=V max hour,

[0127] In the formula, d is the differential, V is the voltage, I is the current, V max is the maximum voltage.

[0128] According to the relationship between dP / dV and I / V, the operating point voltage is changed to achieve the best power tracking point;

[0129] In specific applications, such as Figure 2As shown, Vx and Ik are the current values, and then the voltage and current change process is obtained by comparison based on the previous values. First, determine whether the denominator dV is zero. If it is zero, no adjustment is required. If dV is zero, it means that dI is not 0 and no adjustment is required. The direction of the current is determined to adjust the voltage, and then the reference voltage value is changed based on the basis given by the measured value V. This is the advantage of the incremental conductance strategy.

[0130] Essentially, the incremental conductance method does not produce oscillations after reaching the optimal power point; when the conditions for the optimal power point are met, the optimal point will remain stable in the corresponding state;

[0131] The incremental conductance method has good applicability and will not cause malfunction even when the environmental conditions change rapidly. The best point tracking of this method is based on dI / dV=-I / V as the judgment condition. If dI / dV>-I / V, the best working point is at P max On the left side, if dI / dV<-I / V, the optimal operating point is at P max On the right, from a basic theoretical point of view, the incremental conductance method has nothing to do with the speed of changes in the external environment, and can accurately track the optimal power point;

[0132] In one embodiment, the construction of the perturbation and observation method includes the following steps:

[0133] Increase or decrease the output voltage of the distributed photovoltaic panel array within a fixed cycle, measure the direction of power change at the output point, and determine and adjust the control signal for the next cycle;

[0134] The output power feedback method is adopted to obtain the output voltage and current of the distributed photovoltaic panel array through the current transformer and the voltage transformer, and the load power value is obtained through calculation;

[0135] Under stable working conditions, the perturbation and observation method will make optimal adjustments at the best power point according to the numerical changes in the load power value.

[0136] In specific applications, during the conversion process of solar photovoltaic cells, the output of the distributed photovoltaic panel array is adjusted with a relatively small step size in each adjustment cycle. The adjustment step size is fixed, and the adjustment direction is to increase or decrease. The controlled object is the voltage or working current output by the distributed photovoltaic panel array. This adjustment process is called "disturbance". By comparing the output power of the distributed photovoltaic panel array before and after the disturbance cycle, if △P>0, it means that the direction of the reference value voltage change is correct, and the original change direction "disturbance" can continue to be tracked; if △P<0, it means that the direction of the predetermined value voltage change is wrong, and the direction of the "disturbance" needs to be adjusted. When the given predetermined value voltage increases, if the output total power also increases, the optimal working point is at the optimal power point P max On the left, the reference voltage needs to be adjusted further to increase the voltage value; if the output power of the photovoltaic cell decreases, the optimal operating point is at the optimal power point P max On the right side, the reference voltage value needs to be reduced;

[0137] When the preset voltage decreases, if the load power also decreases, the optimal point is at P max To the left of the preset voltage, if the output power is adjusted to increase, the optimal working point position P max On the right side, the reference voltage needs to be changed further;

[0138] In this way, the power operating point of the solar cell array can gradually approach the current optimal power point, and will eventually be adjusted to a smaller range to a steady state. If the step size is large, this disturbance tracking algorithm can obtain a fast tracking point, but if the step size is small, the speed is relatively slow, the step size is relatively poor, and the step size is relatively good.

[0139] like Figure 3 As shown, the disturbance observation method is simple and easy, requires fewer measurement parameters, and is simple to implement. From the above description and analysis, it can be seen that it is only necessary to collect the load voltage of the photovoltaic cell array and the load battery to calculate the total power and compare it with the previous power. According to the comparison result, the next adjustment direction (usually also called the disturbance direction) is determined.

[0140] The motor load 7 is used to work according to the received alternating current sent by the frequency converter.

[0141] In summary, with the aid of the above technical solutions of the present invention, the present invention connects the distributed power supply, the public power grid and the motor load to the inverter respectively, so that the motor load can receive the power of the distributed power supply through the inverter and work normally even when the public power grid is unavailable; the disturbance observation method of the present invention is simple and easy, requires fewer measurement parameters, and is simple to implement. From the above description and analysis, it can be seen that it is only necessary to collect the load voltage of the photovoltaic cell array and the load battery to calculate the total power and compare it with the previous power, and the direction of the next adjustment can be judged according to the comparison result; the incremental conductance method of the present invention will not produce oscillation after reaching the optimal power point; when the conditions meet the conditions of the optimal power point, the optimal point will remain stable in the corresponding state; the incremental conductance method will not malfunction when the environmental conditions change rapidly, and has good applicability.

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A flexible power supply system for efficient utilization of distributed photovoltaic storage, characterized in that: Including distributed photovoltaic power generation module, distributed photovoltaic energy storage module, inverter, public power grid, maximum power point tracking module, maximum power point analysis module and motor load; The distributed photovoltaic power generation module, the distributed photovoltaic energy storage module, the inverter, the motor load and the public power grid are connected in sequence; The public power grid is connected to the maximum power point tracking module and the maximum power point analysis module; The distributed photovoltaic power generation module is used to directly convert solar energy into electrical energy through photovoltaic components; The distributed photovoltaic energy storage module is used to convert the distributed photovoltaic power generation module into alternating current through the inverter and store the alternating current in the public power grid; The frequency converter is used to control the AC power by changing the frequency of the motor's working power supply; The public power grid is used to transmit alternating current; The high power point tracking module is used to track the maximum power point of distributed photovoltaic power generation; The maximum power point analysis module is used to analyze the maximum power point of distributed photovoltaic power generation and reduce energy loss during operation; The motor load is used to work according to the received alternating current sent by the frequency converter; The method for tracking the maximum power point of distributed photovoltaic power generation also includes the following steps: When light shines on the distributed photovoltaic panels, electron-hole pairs are generated. The carriers generated near the internal junction of the semiconductor are not recombined and reach the space charge region. Attracted by the strong electric field, the electrons flow into the N region and the holes flow into the P region. If the external circuit is short-circuited, a photocurrent proportional to the incident light flux will flow in the external circuit; When both ends of the PN junction are open, electrons and holes flow into the N region and the P region respectively, causing the Fermi level of the N region to be higher than that of the P region, and a potential difference is generated between the two Fermi levels. Measure the vertical potential difference and determine the maximum power point; The method of measuring the vertical potential difference and determining the maximum power point also includes the following steps: Calculate the volt-ampere characteristics of distributed photovoltaic panels; According to the power of distributed photovoltaic panels, the voltage is derived and the maximum power point is obtained; The calculation formula of the maximum power point is as follows: make ,but set up is the panel power. Since power is equal to the product of current and voltage, that is: Taking the derivative of the voltage at both ends yields: Maximum Power Point: In the formula, in the formula, is the panel current, is the battery panel voltage, is the short-circuit current of the distributed photovoltaic panels is the diode reverse saturation current, is the electron charge, K is the Boltzmann constant, T is the absolute temperature, and d is the differential.

2. According to claim 1, a flexible power supply system for efficient utilization of distributed photovoltaic storage is characterized in that: The frequency converter comprises a first bidirectional converter, an inverter and a DC bus, wherein the first bidirectional converter and the inverter are connected via the DC bus; The first bidirectional converter is connected to the public grid and is used to convert the AC power received from the public grid into DC power and output it to the DC bus, and convert the DC power sent by the DC bus into AC power and output it to the public grid; The inverter is connected to the motor load and is used for converting the direct current sent by the direct current bus into alternating current and outputting it to the motor load.

3. According to claim 1, a flexible power supply system for efficient utilization of distributed photovoltaic storage is characterized in that: The high power point tracking module includes a control module, a PWM generation module, an A / D conversion module, a sampling adjustment circuit module, and a driving circuit module; Among them, the control module mainly operates the data of the A / D conversion module, finds the maximum power point, and controls the output duty cycle of the PWM module; The control module, PWM generation module and A / D conversion module can be controlled by a single chip microcomputer and together with other peripheral hardware form a solar energy conversion device.

4. According to claim 3, a flexible power supply system for efficient utilization of distributed photovoltaic storage is characterized in that: The distributed photovoltaic power generation panels are divided into plastic shell filled resin type, glass shell type and metal base type according to their structure; Wherein, the plastic shell is filled with resin type, and a transparent plastic material with good weather resistance is used for the outer wall, and the distributed photovoltaic cell pieces are filled with water-resistant transparent resin; The glass shell type uses tempered glass for the main part of the outer wall, the outer periphery is fixed with a rust-proof metal frame, and the interior is filled with water-resistant resin; The metal base type is used in a metal base that has been rust-proofed and a shell formed by a glass-reinforced plastic laminate, and is equipped with a pre-connected distributed photovoltaic cell element group and a structure filled with a water-resistant transparent resin. In order to prevent dust impurities in the air from adhering to the surface of the transparent resin, a layer of plastic material with good slip performance is applied.

5. According to claim 1, a flexible power supply system for efficient utilization of distributed photovoltaic storage is characterized in that: The method for analyzing the maximum power point of distributed photovoltaic power generation and reducing energy loss during operation also includes the following steps: The incremental conductance method is used to track the optimal power point, and the output voltage form of the solar photovoltaic cell array is adjusted to achieve the purpose of maximum power tracking; The maximum power point of distributed photovoltaic power generation is analyzed based on the perturbation observation method, and the distributed photovoltaic power generation cells are configured to a voltage near the maximum output power point according to the requirements of the inverter DC side voltage.

6. A flexible power supply system for efficient utilization of distributed photovoltaic energy storage according to claim 5, characterized in that: The incremental conductance method construction comprises the following steps: Construct the PV curve of the distributed photovoltaic power generation battery array. At the maximum power point, the derivative of power to voltage is zero; When the output power is not at the maximum power point, the tracking direction of the control algorithm can be determined according to the positive and negative values ​​of dP / dV, that is, at the maximum power point: When dP / dV=0 at the maximum power point; When dP / dV>0 is on the left side of the maximum power point; When dP / dV<0, it is on the right side of the maximum power point; The voltage and current of the photovoltaic array are expressed as follows: when In the formula, d is the differential, V is the voltage, and I is the current. is the maximum voltage; according to The relationship between I / V is used to change the operating point voltage to achieve the optimal power tracking point.

7. A flexible power supply system for efficient utilization of distributed photovoltaic energy storage according to claim 6, characterized in that: The construction of the perturbation and observation method includes the following steps: Increase or decrease the output voltage of the distributed photovoltaic panel array within a fixed cycle, measure the direction of power change at the output point, and determine and adjust the control signal for the next cycle; The output power feedback method is adopted to obtain the output voltage and current of the distributed photovoltaic panel array through the current transformer and the voltage transformer, and the load power value is obtained through calculation; Under stable working conditions, the perturbation and observation method will make optimal adjustments at the best power point according to the numerical changes in the load power value.

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