Photovoltaic grid-connected inverter control method and system

Abstract

The invention is suitable for the field of photovoltaic equipment control, and provides a photovoltaic grid-connected inverter control method and system, and the method comprises the steps: collecting photovoltaic array information and photovoltaic array related power grid information in real time; the photovoltaic array information comprises output voltage and output current information, and the photovoltaic array associated power grid information comprises voltage, frequency and phase information; dynamically adjusting the working point of the photovoltaic array based on the photovoltaic array information; based on photovoltaic array associated power grid information, locking a power grid phase, and generating a reference signal synchronized with a power grid; according to the method and the system, on one hand, the power generation potential of the photovoltaic array is fully excavated by optimizing maximum power point tracking; and on the other hand, the accurate phase-locked loop technology and harmonic suppression measures ensure reliable compatibility of the inverter and the power grid, reduce interference to the power grid, improve the stability of the power system, and adapt to power grid standards in different regions.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic equipment control, and in particular relates to a photovoltaic grid-connected inverter control method and system. Background Art

[0002] As the global demand for clean energy grows, solar energy has been widely used as a sustainable and pollution-free energy form. Photovoltaic grid-connected power generation system has become an important way to utilize solar energy, and photovoltaic grid-connected inverter is one of the key components of the system.

[0003] There are many challenges in the existing photovoltaic grid-connected technology. Frequent changes in natural factors such as light intensity and ambient temperature will cause the DC voltage and current output of the photovoltaic array to be unstable, affecting the power generation efficiency and power quality. Traditional control methods are difficult to quickly and accurately track the maximum power point, so that photovoltaic cells cannot always work in the best state, resulting in energy waste, restricting the further promotion and efficient use of photovoltaic grid-connected power generation technology. An innovative control method and system are urgently needed to solve this problem. Summary of the invention

[0004] The object of the present invention is to provide a photovoltaic grid-connected inverter control method and system, aiming to solve the problems raised in the above background technology.

[0005] The present invention is implemented in this way. On the one hand, a photovoltaic grid-connected inverter control method comprises:

[0006] Real-time collection of photovoltaic array information and photovoltaic array-related power grid information; the photovoltaic array information includes output voltage and output current information, and the photovoltaic array-related power grid information includes voltage, frequency, and phase information;

[0007] Based on the photovoltaic array information, dynamically adjust the working point of the photovoltaic array;

[0008] Based on the grid information associated with the photovoltaic array, the grid phase is locked and a reference signal synchronized with the grid is generated;

[0009] Acquire and identify reference signals, generate inverter control instructions, and output harmonic suppression signals.

[0010] As a further solution of the present invention, the dynamically adjusting the working point of the photovoltaic array based on the photovoltaic array information specifically includes:

[0011] Calculate the first real-time output power of the photovoltaic array based on the output voltage and output current information of the photovoltaic array;

[0012] Obtaining a preset initial maximum power reference value;

[0013] Comparing the first real-time output power of the photovoltaic array with a preset initial maximum power reference value;

[0014] If the first real-time output power of the photovoltaic array is less than the preset initial maximum power reference value, and the output voltage of the photovoltaic array is less than the preset voltage threshold, a boost adjustment instruction is generated;

[0015] If the first real-time output power of the photovoltaic array is less than the preset initial maximum power reference value, and the output voltage of the photovoltaic array is greater than the preset voltage threshold, a voltage reduction adjustment instruction is generated.

[0016] As a further solution of the present invention, the dynamically adjusting the working point of the photovoltaic array based on the photovoltaic array information specifically further includes:

[0017] Positioning the photovoltaic array corresponding to the targeting step length;

[0018] Based on the boost adjustment command and the target step size, a positive disturbance is applied to the output voltage of the photovoltaic array;

[0019] Based on the step-down adjustment instruction and the target step size, a reverse disturbance is applied to the output voltage of the photovoltaic array;

[0020] After a preset period of time after applying a forward disturbance or a reverse disturbance, real-time acquisition of the photovoltaic array output voltage and output current information is performed to calculate a second real-time output power of the photovoltaic array;

[0021] If the second real-time output power is greater than the first real-time output power, the forward disturbance or the reverse disturbance is applied repeatedly for multiple times, and after each application of the forward disturbance or the reverse disturbance, a third real-time output power of the photovoltaic array is calculated;

[0022] Calculating a rate of change of a third real-time output power;

[0023] When the change rate of the third real-time output power is within the change rate range threshold, the current photovoltaic array output voltage and current are locked and stored.

[0024] As a further solution of the present invention, the positioning photovoltaic array corresponding to the targeting step length specifically includes:

[0025] Identify the material and specification information of the photovoltaic array;

[0026] Obtain the voltage and current comparison table of photovoltaic arrays with corresponding materials and specifications;

[0027] Based on the voltage and current comparison table, the target step size is matched and output.

[0028] As a further solution of the present invention, the method of locking the grid phase and generating a reference signal synchronized with the grid based on the photovoltaic array associated grid information specifically includes:

[0029] Import the voltage information in the photovoltaic array associated power grid information to generate the targeted phase;

[0030] Calculating the phase difference between the target phase and the preset phase;

[0031] generating an error voltage signal based on the phase difference;

[0032] Import error voltage signal to generate output frequency;

[0033] Based on the output frequency, determine the target grid frequency, and judge whether the phase difference is within the phase difference threshold range;

[0034] If the phase difference is within the phase difference threshold range, a standard sine wave reference signal is generated.

[0035] As a further solution of the present invention, the steps of acquiring and identifying a reference signal, generating an inverter control instruction, and outputting a harmonic suppression signal specifically include:

[0036] Obtain a standard sine wave reference signal;

[0037] Based on the standard sine wave reference signal, determine and send the opening and closing sequence and opening and closing duration of the inverter in different time periods;

[0038] Monitor inverter harmonic information, calculate and generate compensation signals.

[0039] As a further solution of the present invention, on the other hand, a photovoltaic grid-connected inverter control system comprises:

[0040] A first real-time acquisition module is used to collect photovoltaic array information and photovoltaic array associated power grid information;

[0041] A dynamic adjustment module is used to dynamically adjust the working point of the photovoltaic array based on the photovoltaic array information;

[0042] A locking module, used to lock the grid phase based on the photovoltaic array associated grid information;

[0043] A first generating module, used to generate a reference signal synchronized with the power grid;

[0044] An acquisition module, used for acquiring and identifying a reference signal;

[0045] A second generating module, used for generating inverter control instructions;

[0046] The output module is used to output harmonic suppression signals.

[0047] As a further solution of the present invention, the dynamic adjustment module specifically includes:

[0048] A first calculation unit, used for calculating a first real-time output power of the photovoltaic array based on the output voltage and output current information of the photovoltaic array;

[0049] An acquisition unit, used for acquiring a preset initial maximum power reference value;

[0050] A comparison unit, used for comparing a first real-time output power of the photovoltaic array with a preset initial maximum power reference value;

[0051] A first generating unit, configured to generate a boost adjustment instruction if the first real-time output power of the photovoltaic array is less than a preset initial maximum power reference value and the output voltage of the photovoltaic array is less than a preset voltage threshold;

[0052] The second generating unit is used to generate a voltage reduction adjustment instruction if the first real-time output power of the photovoltaic array is less than a preset initial maximum power reference value and the output voltage of the photovoltaic array is greater than a preset voltage threshold.

[0053] As a further solution of the present invention, the dynamic adjustment module specifically further includes:

[0054] A positioning module, used to locate the photovoltaic array corresponding to the target step length;

[0055] A forward disturbance unit, used for applying a forward disturbance to the output voltage of the photovoltaic array based on a boost adjustment instruction and a target step size;

[0056] A reverse disturbance unit, used for applying a reverse disturbance to the output voltage of the photovoltaic array based on the voltage reduction adjustment instruction and the target step size;

[0057] A second real-time acquisition unit is used to collect the output voltage and output current information of the photovoltaic array in real time after a preset period of time after applying the forward disturbance or the reverse disturbance;

[0058] A second calculation unit, used for calculating a second real-time output power of the photovoltaic array;

[0059] A repeated application unit, used for repeatedly applying the forward disturbance or the reverse disturbance for multiple times if the second real-time output power is greater than the first real-time output power;

[0060] A third calculation unit, used for calculating a third real-time output power of the photovoltaic array after applying the forward disturbance or the reverse disturbance each time;

[0061] a fourth calculation unit, configured to calculate a change rate of a third real-time output power;

[0062] The locking storage unit is used to lock and store the current photovoltaic array output voltage and current when the change rate of the third real-time output power is within the change rate range threshold.

[0063] The present invention provides a photovoltaic grid-connected inverter control method and system. On the one hand, the method and system optimize the maximum power point tracking to fully tap the photovoltaic array power generation potential, reduce energy waste, and improve the system power generation efficiency. On the other hand, precise phase-locked loop technology and harmonic suppression measures ensure reliable compatibility between the inverter and the power grid, reduce interference to the power grid, improve the stability of the power system, adapt to the power grid standards of different regions, and effectively promote the widespread application of photovoltaic grid-connected power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 The invention is a main flow chart of a photovoltaic grid-connected inverter control method.

[0065] Figure 2 The invention is a flow chart of a first embodiment of dynamically adjusting the working point of a photovoltaic array based on photovoltaic array information in a photovoltaic grid-connected inverter control method.

[0066] Figure 3 The invention is a flow chart of a second embodiment of dynamically adjusting the working point of a photovoltaic array based on photovoltaic array information in a photovoltaic grid-connected inverter control method.

[0067] Figure 4 The invention discloses a flow chart for positioning a photovoltaic array corresponding to a target step length in a photovoltaic grid-connected inverter control method.

[0068] Figure 5 The invention discloses a flow chart of a photovoltaic grid-connected inverter control method for locking a grid phase based on photovoltaic array-related grid information to generate a reference signal synchronized with the grid.

[0069] Figure 6 The invention discloses a flow chart for obtaining and identifying a reference signal, generating an inverter control instruction and outputting a harmonic suppression signal in a photovoltaic grid-connected inverter control method.

[0070] Figure 7 It is a main structure diagram of a photovoltaic grid-connected inverter control system.

[0071] Figure 8 The present invention is a structural block diagram of a first embodiment of a dynamic adjustment module in a photovoltaic grid-connected inverter control system.

[0072] Fig. 9 The present invention is a structural block diagram of a second embodiment of a dynamic adjustment module in a photovoltaic grid-connected inverter control system. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0074] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0075] The present invention provides a photovoltaic grid-connected inverter control method and system, which solves the technical problems in the background technology.

[0076] like Figure 1 As shown, it is a main flow chart of a photovoltaic grid-connected inverter control method provided by an embodiment of the present invention, and the photovoltaic grid-connected inverter control method includes:

[0077] Step S100: real-time collection of photovoltaic array information and photovoltaic array-related power grid information;

[0078] The photovoltaic array information includes output voltage and output current information, and the photovoltaic array associated power grid information includes voltage, frequency, and phase information;

[0079] Step S200: dynamically adjusting the working point of the photovoltaic array based on the photovoltaic array information;

[0080] Step S300: Based on the photovoltaic array associated grid information, lock the grid phase and generate a reference signal synchronized with the grid;

[0081] Step S400: acquiring and identifying a reference signal, generating an inverter control instruction, and outputting a harmonic suppression signal;

[0082] When this embodiment is applied, first, the output voltage and output current information of the photovoltaic array, as well as the voltage, frequency, and phase information of the associated power grid are obtained in real time and accurately. These information serve as the key basis for subsequent control actions. Based on the collected photovoltaic array information, the maximum power point tracking algorithm is introduced. The algorithm can dynamically perceive changes in the external environment, especially the fluctuations in light intensity and ambient temperature, and quickly adjust the working point of the photovoltaic array so that it always approaches the maximum power output state, greatly improving the power generation efficiency. At the same time, based on the photovoltaic array-related power grid information, the phase-locked loop technology is used to accurately lock the power grid phase, generate a reference signal that is completely synchronized with the power grid, and ensure that the inverter outputs AC power that can be seamlessly connected to the power grid. Further, the system can quickly obtain and identify the reference signal, generate inverter control instructions based on this, accurately control the inverter switching devices, and smoothly realize the conversion of DC to AC power and the grid connection process. In addition, in this process, the harmonic suppression signal can also be synchronously output, and the active or passive power filter and inverter control work together to effectively filter out the harmonic components in the grid-connected current to ensure that the power quality meets the grid access standards.

[0083] like Figure 2 As shown, as a preferred embodiment of the present invention, the dynamically adjusting the working point of the photovoltaic array based on the photovoltaic array information specifically includes:

[0084] Step S201: Calculating the first real-time output power of the photovoltaic array based on the output voltage and output current information of the photovoltaic array;

[0085] Step S202: obtaining a preset initial maximum power reference value;

[0086] Step S203: comparing the first real-time output power of the photovoltaic array with a preset initial maximum power reference value;

[0087] Step S204: if the first real-time output power of the photovoltaic array is less than the preset initial maximum power reference value, and the output voltage of the photovoltaic array is less than the preset voltage threshold, a boost adjustment instruction is generated;

[0088] Step S205: if the first real-time output power of the photovoltaic array is less than the preset initial maximum power reference value, and the output voltage of the photovoltaic array is greater than the preset voltage threshold, a voltage reduction adjustment instruction is generated;

[0089] When this embodiment is applied, first, the output voltage and output current information of the photovoltaic array are captured in real time, and based on this, the first real-time output power of the photovoltaic array is accurately calculated using the power calculation formula. At the same time, the initial maximum power reference value is preset, which is set based on comprehensive factors such as the ideal working conditions of the photovoltaic array, historical power generation data, and the average illumination conditions of the local environment, as a key scale for subsequent judgment. Then, the first real-time output power is compared with the preset initial maximum power reference value. When it is found that the first real-time output power of the photovoltaic array is less than the preset value, the adjustment direction is further determined by combining the relationship between the output voltage of the photovoltaic array and the preset voltage threshold. If the output voltage of the photovoltaic array is less than the preset voltage threshold at this moment, it means that the current working point is likely to be on the left side of the maximum power point. According to the voltage-power characteristics of the photovoltaic array, the voltage increase is expected to increase the power, so a boost adjustment instruction is generated to prompt the subsequent control link to increase the voltage appropriately; on the contrary, if the output voltage of the photovoltaic array is greater than the preset voltage threshold, it indicates that the working point is on the right side of the maximum power point. At this time, the voltage increase will cause the power to decrease, so a voltage reduction adjustment instruction is generated to guide the system to reduce the voltage. Through this series of rigorous and orderly steps, the working point of the photovoltaic array is continuously and dynamically adjusted, and repeated comparisons and adjustments are made until the power reaches or approaches the maximum value, allowing the photovoltaic array to operate stably in the high-efficiency power generation range, maximizing energy utilization efficiency and ensuring the stability of the photovoltaic grid-connected power generation system.

[0090] like Figure 3 As shown, as a preferred embodiment of the present invention, the dynamically adjusting the working point of the photovoltaic array based on the photovoltaic array information specifically further includes:

[0091] Step S211: positioning the photovoltaic array corresponding to the target step length;

[0092] Step S212: applying a positive disturbance to the output voltage of the photovoltaic array based on the boost adjustment instruction and the target step size;

[0093] Step S213: applying a reverse disturbance to the output voltage of the photovoltaic array based on the voltage reduction adjustment instruction and the target step size;

[0094] Step S214: after a preset period of time after applying the forward disturbance or the reverse disturbance, real-time acquisition of the photovoltaic array output voltage and output current information, and calculation of the second real-time output power of the photovoltaic array;

[0095] Step S215: if the second real-time output power is greater than the first real-time output power, repeatedly applying the forward disturbance or the reverse disturbance multiple times, and calculating the third real-time output power of the photovoltaic array after each application of the forward disturbance or the reverse disturbance;

[0096] Step S216: calculating the change rate of the third real-time output power;

[0097] Step S217: when the change rate of the third real-time output power is within the change rate range threshold, locking and storing the current photovoltaic array output voltage and current;

[0098] When this embodiment is applied, the target step size corresponding to the photovoltaic array is first located. Once the boost adjustment instruction is generated, based on the target step size, a positive disturbance is accurately applied to the photovoltaic array output voltage to promote a moderate increase in voltage. Similarly, in the face of a voltage reduction adjustment instruction, a reverse disturbance can also be applied based on the target step size to cause the voltage to be reasonably reduced. Within the preset period after the disturbance is applied, the output voltage and current information of the photovoltaic array are collected again in real time, and the second real-time output power of the photovoltaic array is calculated by the power calculation formula and compared with the first real-time output power. If the second real-time output power is greater than the first real-time output power, it means that the current disturbance direction is correct. The system repeats the forward or reverse disturbance for many times, and calculates the third real-time output power of the photovoltaic array after each disturbance, and then obtains its rate of change. The rate of change of the third real-time output power is continuously monitored. When the rate of change is stably within the preset rate of change range threshold, it means that the working point of the photovoltaic array has approached the maximum power point. At this time, the system decisively locks and stores the current photovoltaic array output voltage and current, allowing the array to stably operate in this efficient power generation state. This cycle repeats itself. As external conditions such as light and temperature change dynamically, the system can always respond quickly and make precise adjustments to ensure that the photovoltaic array operates at close to maximum power around the clock, providing a solid guarantee for the continuous and efficient energy supply of the photovoltaic grid-connected power generation system.

[0099] like Figure 4 As shown, as a preferred embodiment of the present invention, the positioning photovoltaic array corresponding to the targeting step size specifically includes:

[0100] Step S2111: Identify the material and specification information of the photovoltaic array;

[0101] Step S2112: Obtaining a voltage and current comparison table of photovoltaic arrays of corresponding materials and specifications;

[0102] Step S2113: matching and outputting the target step length based on the voltage and current comparison table;

[0103] It should be understood that the material and specification information of the photovoltaic array must be identified first. Photovoltaic arrays of different materials and specifications have different voltage and current change sensitivities. The voltage and current comparison table of the photovoltaic arrays of corresponding materials and specifications must be obtained. For arrays with high voltage sensitivity, the disturbance step size in the voltage dimension must be set accordingly to prevent excessive adjustment from missing the maximum power point. For arrays with outstanding current sensitivity, the current disturbance step size needs to be finely controlled, and the target step size is matched and output based on the voltage and current comparison table.

[0104] like Figure 5 As shown, as a preferred embodiment of the present invention, the method of locking the grid phase and generating a reference signal synchronized with the grid based on the photovoltaic array associated grid information specifically includes:

[0105] Step S301: importing voltage information in the photovoltaic array associated power grid information to generate a targeted phase;

[0106] Step S302: Calculate the phase difference between the target phase and the preset phase;

[0107] Step S303: generating an error voltage signal based on the phase difference;

[0108] Step S304: importing an error voltage signal to generate an output frequency;

[0109] Step S305: determining the target grid frequency based on the output frequency, and judging whether the phase difference is within the phase difference threshold range;

[0110] Step S306: if the phase difference is within the phase difference threshold range, generate a standard sine wave reference signal;

[0111] When this embodiment is applied, the voltage information in the photovoltaic array-related power grid information is specially imported with the help of a high-precision sensor, and a target phase is generated in combination with a phase detector. This target phase serves as a key reference for subsequent precise control. Then, it is compared with the preset phase and the phase difference is calculated to quantify the deviation of the current power grid phase from the ideal state. Based on the phase difference, an error voltage signal is generated, which carries the key instruction information for phase adjustment. Subsequently, the error voltage signal is introduced into a voltage-controlled oscillator to generate an output frequency, and then the target power grid frequency is locked based on this frequency. At the same time, it is continuously judged whether the phase difference is within the preset threshold range. Once the conditions are met, it indicates that the power grid phase has been accurately locked. Then, based on the current state, a standard sinusoidal wave reference signal is generated to provide accurate synchronization guarantee for the subsequent inverter grid connection and ensure stable power grid access.

[0112] like Figure 6 As shown, as a preferred embodiment of the present invention, the steps of acquiring and identifying a reference signal, generating an inverter control instruction, and outputting a harmonic suppression signal specifically include:

[0113] Step S401: obtaining a standard sine wave reference signal;

[0114] Step S402: Based on the standard sine wave reference signal, determine and send the opening and closing sequence and opening and closing duration of the inverter in different time periods;

[0115] Step S403: monitoring the inverter harmonic information, calculating and generating a compensation signal;

[0116] When this embodiment is applied, a standard sinusoidal wave reference signal is first obtained. Based on the standard sinusoidal wave reference signal, combined with the current photovoltaic array output power status and the preset grid-connected requirements, a control strategy for the inverter switch device is formulated through a preset algorithm, and the opening and closing sequence and duration of each switch tube of the inverter in different time periods are determined and sent to ensure efficient conversion of direct current to alternating current. At the same time, the harmonic information of the inverter is monitored, and a compensation signal is calculated and generated through a harmonic suppression algorithm based on the monitoring results. An active power filter or a passive power filter controlled in coordination with the inverter is used to generate and output a harmonic suppression signal to offset the harmonics in real time, thereby ensuring that the harmonic content of the grid-connected current meets the grid standards.

[0117] like Figure 7 As shown, as another preferred embodiment of the present invention, on the other hand, a photovoltaic grid-connected inverter control system comprises:

[0118] The first real-time acquisition module 100 is used to collect photovoltaic array information and photovoltaic array associated power grid information;

[0119] A dynamic adjustment module 200, used to dynamically adjust the working point of the photovoltaic array based on the photovoltaic array information;

[0120] A locking module 300, used to lock the grid phase based on the photovoltaic array associated grid information;

[0121] A first generating module 400, configured to generate a reference signal synchronized with a power grid;

[0122] An acquisition module 500, used to acquire and identify a reference signal;

[0123] The second generating module 600 is used to generate an inverter control instruction;

[0124] The output module 700 is used to output a harmonic suppression signal.

[0125] When this embodiment is applied, the first real-time acquisition module 100 acquires photovoltaic array information and photovoltaic array-related power grid information. Based on the photovoltaic array information, the dynamic adjustment module 200 dynamically adjusts the working point of the photovoltaic array. Based on the photovoltaic array-related power grid information, the locking module 300 locks the power grid phase. The first generation module 400 generates a reference signal synchronized with the power grid, the acquisition module 500 acquires and identifies the reference signal, the second generation module 600 generates an inverter control instruction, and the output module 700 outputs a harmonic suppression signal.

[0126] like Figure 8 As shown, as another preferred embodiment of the present invention, the dynamic adjustment module 200 specifically includes:

[0127] A first calculation unit 201 is used to calculate a first real-time output power of the photovoltaic array based on the output voltage and output current information of the photovoltaic array;

[0128] An acquisition unit 202 is used to acquire a preset initial maximum power reference value;

[0129] A comparison unit 203, used for comparing the first real-time output power of the photovoltaic array with a preset initial maximum power reference value;

[0130] The first generating unit 204 is used to generate a boost adjustment instruction if the first real-time output power of the photovoltaic array is less than a preset initial maximum power reference value and the output voltage of the photovoltaic array is less than a preset voltage threshold;

[0131] The second generating unit 205 is configured to generate a voltage reduction adjustment instruction if the first real-time output power of the photovoltaic array is less than a preset initial maximum power reference value and the output voltage of the photovoltaic array is greater than a preset voltage threshold.

[0132] When this embodiment is applied, based on the output voltage and output current information of the photovoltaic array, the first calculation unit 201 calculates the first real-time output power of the photovoltaic array, the acquisition unit 202 acquires the preset initial maximum power reference value, and the comparison unit 203 compares the first real-time output power of the photovoltaic array with the preset initial maximum power reference value. If the first real-time output power of the photovoltaic array is less than the preset initial maximum power reference value, and the output voltage of the photovoltaic array is less than the preset voltage threshold, the first generation unit 204 generates a boost adjustment instruction. If the first real-time output power of the photovoltaic array is less than the preset initial maximum power reference value, and the output voltage of the photovoltaic array is greater than the preset voltage threshold, the second generation unit 205 generates a buck adjustment instruction.

[0133] like Fig. 9 As shown, as another preferred embodiment of the present invention, the dynamic adjustment module 200 specifically further includes:

[0134] A positioning unit 206, used for positioning the photovoltaic array corresponding to the targeting step length;

[0135] A forward disturbance unit 207, used to apply a forward disturbance to the photovoltaic array output voltage based on the boost adjustment instruction and the target step size;

[0136] A reverse disturbance unit 208, for applying a reverse disturbance to the photovoltaic array output voltage based on the voltage reduction adjustment instruction and the target step size;

[0137] A second real-time acquisition unit 209 is used to collect the output voltage and output current information of the photovoltaic array in real time after a preset period of time after applying the forward disturbance or the reverse disturbance;

[0138] The second calculation unit 210 is used to calculate the second real-time output power of the photovoltaic array;

[0139] A repeated application unit 211, configured to repeatedly apply the forward disturbance or the reverse disturbance for multiple times if the second real-time output power is greater than the first real-time output power;

[0140] A third calculation unit 212 is used to calculate a third real-time output power of the photovoltaic array after applying the forward disturbance or the reverse disturbance each time;

[0141] A fourth calculation unit 213, configured to calculate a change rate of a third real-time output power;

[0142] The locking storage unit 214 is used to lock and store the current photovoltaic array output voltage and current when the change rate of the third real-time output power is within the change rate range threshold.

[0143] When this embodiment is applied, the positioning unit 206 identifies the target step corresponding to the photovoltaic array, and based on the boost adjustment instruction and the target step, the forward disturbance unit 207 applies a forward disturbance to the photovoltaic array output voltage. Based on the buck adjustment instruction and the target step, the reverse disturbance unit 208 applies a reverse disturbance to the photovoltaic array output voltage. After a preset period of time after applying the forward disturbance or the reverse disturbance, the second real-time acquisition unit 209 collects the output voltage and output current information of the photovoltaic array in real time, and the second calculation unit 210 calculates the second real-time output power of the photovoltaic array. If the second real-time output power is greater than the first real-time output power, the repeated application unit 211 repeatedly applies the forward disturbance or the reverse disturbance for multiple times. After each application of the forward disturbance or the reverse disturbance, the third calculation unit 212 calculates the third real-time output power of the photovoltaic array, and the fourth calculation unit 213 calculates the change rate of the third real-time output power. When the change rate of the third real-time output power is within the change rate range threshold, the locking storage unit 214 locks and stores the current photovoltaic array output voltage and current.

[0144] In the above embodiment of the present invention, a photovoltaic grid-connected inverter control method is provided, and a photovoltaic grid-connected inverter control system is provided. First, the output voltage and output current information of the photovoltaic array, as well as the voltage, frequency, and phase information of the associated power grid are obtained in real time and accurately. These information are used as the key basis for subsequent control actions. Based on the collected photovoltaic array information, a maximum power point tracking algorithm is introduced. The algorithm can dynamically perceive changes in the external environment, especially fluctuations in light intensity and ambient temperature, and quickly adjust the photovoltaic array working point so that it always approaches the maximum power output state, greatly improving the power generation efficiency. At the same time, based on the photovoltaic array-related power grid information, the phase-locked loop technology is used to accurately lock the power grid phase, generate a reference signal that is completely synchronized with the power grid, and ensure that the inverter outputs AC power and can be seamlessly connected to the power grid. Furthermore, the system can quickly obtain and identify the reference signal, generate inverter control instructions accordingly, accurately control the inverter switch device, and smoothly realize the conversion of DC to AC power and the grid connection process. Moreover, in this process, the harmonic suppression signal can be synchronously output, and the active or passive power filter and inverter control can be used to effectively filter out the harmonic components in the grid-connected current, ensuring that the power quality meets the grid access standards. On the one hand, this method and system optimizes the maximum power point tracking to fully tap the power generation potential of the photovoltaic array, reduce energy waste, and improve the power generation efficiency of the system. On the other hand, precise phase-locked loop technology and harmonic suppression measures ensure reliable compatibility between the inverter and the grid, reduce interference to the grid, improve the stability of the power system, adapt to the grid standards of different regions, and effectively promote the widespread application of photovoltaic grid-connected power generation.

[0145] In order to load the above-mentioned method and system and enable it to run smoothly, the system, in addition to the various modules mentioned above, may also include more or fewer components than described above, or a combination of certain components, or different components, for example, it may include input and output devices, network access devices, buses, processors and memories, etc.

[0146] The processor may be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the system, and various interfaces and lines are used to connect various parts.

[0147] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0148] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0149] 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 and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A photovoltaic grid-connected inverter control method, characterized in that: The method comprises: Real-time collection of photovoltaic array information and photovoltaic array-related power grid information; the photovoltaic array information includes output voltage and output current information, and the photovoltaic array-related power grid information includes voltage, frequency, and phase information; Based on the photovoltaic array information, dynamically adjust the working point of the photovoltaic array; Based on the grid information associated with the photovoltaic array, the grid phase is locked and a reference signal synchronized with the grid is generated; Acquire and identify reference signals, generate inverter control instructions, and output harmonic suppression signals.

2. The photovoltaic grid-connected inverter control method according to claim 1, characterized in that: The dynamically adjusting the working point of the photovoltaic array based on the photovoltaic array information specifically includes: Calculate the first real-time output power of the photovoltaic array based on the output voltage and output current information of the photovoltaic array; Obtaining a preset initial maximum power reference value; Comparing the first real-time output power of the photovoltaic array with a preset initial maximum power reference value; If the first real-time output power of the photovoltaic array is less than the preset initial maximum power reference value, and the output voltage of the photovoltaic array is less than the preset voltage threshold, a boost adjustment instruction is generated; If the first real-time output power of the photovoltaic array is less than the preset initial maximum power reference value, and the output voltage of the photovoltaic array is greater than the preset voltage threshold, a voltage reduction adjustment instruction is generated.

3. The photovoltaic grid-connected inverter control method according to claim 1, characterized in that: The dynamically adjusting the working point of the photovoltaic array based on the photovoltaic array information specifically includes: Positioning the photovoltaic array corresponding to the targeting step length; Based on the boost adjustment command and the target step size, a positive disturbance is applied to the output voltage of the photovoltaic array; Based on the step-down adjustment instruction and the target step size, a reverse disturbance is applied to the output voltage of the photovoltaic array; After a preset period of time after applying a forward disturbance or a reverse disturbance, real-time acquisition of the photovoltaic array output voltage and output current information is performed to calculate a second real-time output power of the photovoltaic array; If the second real-time output power is greater than the first real-time output power, the forward disturbance or the reverse disturbance is applied repeatedly for multiple times, and after each application of the forward disturbance or the reverse disturbance, a third real-time output power of the photovoltaic array is calculated; Calculating a rate of change of a third real-time output power; When the change rate of the third real-time output power is within the change rate range threshold, the current photovoltaic array output voltage and current are locked and stored.

4. The photovoltaic grid-connected inverter control method according to claim 3, characterized in that: The targeting step length corresponding to the positioning photovoltaic array specifically includes: Identify the material and specification information of the photovoltaic array; Obtain the voltage and current comparison table of photovoltaic arrays with corresponding materials and specifications; Based on the voltage and current comparison table, the target step size is matched and output.

5. The photovoltaic grid-connected inverter control method according to claim 1, characterized in that: The method of locking the grid phase and generating a reference signal synchronized with the grid based on the photovoltaic array associated grid information specifically includes: Import the voltage information in the photovoltaic array associated power grid information to generate the targeted phase; Calculating the phase difference between the target phase and the preset phase; generating an error voltage signal based on the phase difference; Import error voltage signal to generate output frequency; Based on the output frequency, determine the target grid frequency, and judge whether the phase difference is within the phase difference threshold range; If the phase difference is within the phase difference threshold range, a standard sine wave reference signal is generated.

6. The photovoltaic grid-connected inverter control method according to claim 5, characterized in that: The obtaining and identifying the reference signal, generating the inverter control instruction, and outputting the harmonic suppression signal specifically includes: Obtain a standard sine wave reference signal; Based on the standard sine wave reference signal, determine and send the opening and closing sequence and opening and closing duration of the inverter in different time periods; Monitor inverter harmonic information, calculate and generate compensation signals.

7. A photovoltaic grid-connected inverter control system, characterized in that: The photovoltaic grid-connected inverter control method according to any one of claims 1 to 6 is applied, wherein the system comprises: A first real-time acquisition module is used to collect photovoltaic array information and photovoltaic array associated power grid information; A dynamic adjustment module is used to dynamically adjust the working point of the photovoltaic array based on the photovoltaic array information; A locking module, used to lock the grid phase based on the photovoltaic array associated grid information; A first generating module, used to generate a reference signal synchronized with the power grid; An acquisition module, used for acquiring and identifying a reference signal; A second generating module, used for generating inverter control instructions; The output module is used to output harmonic suppression signals.

8. The photovoltaic grid-connected inverter control system according to claim 7, characterized in that: The dynamic adjustment module specifically includes: A first calculation unit, used for calculating a first real-time output power of the photovoltaic array based on the output voltage and output current information of the photovoltaic array; An acquisition unit, used for acquiring a preset initial maximum power reference value; A comparison unit, used for comparing a first real-time output power of the photovoltaic array with a preset initial maximum power reference value; A first generating unit, configured to generate a boost adjustment instruction if the first real-time output power of the photovoltaic array is less than a preset initial maximum power reference value and the output voltage of the photovoltaic array is less than a preset voltage threshold; The second generating unit is used to generate a voltage reduction adjustment instruction if the first real-time output power of the photovoltaic array is less than a preset initial maximum power reference value and the output voltage of the photovoltaic array is greater than a preset voltage threshold.

9. The photovoltaic grid-connected inverter control system according to claim 7, characterized in that: The dynamic adjustment module specifically includes: A positioning unit, used to locate the photovoltaic array corresponding to the target step length; A forward disturbance unit, used for applying a forward disturbance to the output voltage of the photovoltaic array based on a boost adjustment instruction and a target step size; A reverse disturbance unit, used for applying a reverse disturbance to the output voltage of the photovoltaic array based on the voltage reduction adjustment instruction and the target step size; A second real-time acquisition unit is used to collect the output voltage and output current information of the photovoltaic array in real time after a preset period of time after applying the forward disturbance or the reverse disturbance; A second calculation unit, used for calculating a second real-time output power of the photovoltaic array; A repeated application unit, used for repeatedly applying the forward disturbance or the reverse disturbance for multiple times if the second real-time output power is greater than the first real-time output power; A third calculation unit, used for calculating a third real-time output power of the photovoltaic array after applying the forward disturbance or the reverse disturbance each time; a fourth calculation unit, configured to calculate a change rate of a third real-time output power; The locking storage unit is used to lock and store the current photovoltaic array output voltage and current when the change rate of the third real-time output power is within the change rate range threshold.

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