Collaborative Protection and Control Method and System for Integrated Photovoltaic-Storage-Charging Systems

Abstract

This invention discloses a collaborative protection control method and system for an integrated photovoltaic-storage-charging system. The method includes: generating an injection control command and sending it to a harmonic feature injection module for harmonic injection; continuously collecting impedance monitoring data at intervals and generating impedance reference data; then detecting whether the newly collected impedance monitoring data deviates from the impedance reference data according to islanding detection rules; if it deviates, sending a signal blocking command and a shutdown command to the bidirectional grid-connected converter; sending a mode switching command to the bidirectional grid-connected converter to switch to a grid-type operating mode and monitoring impedance monitoring data to determine if there is a risk of electric shock; if there is a risk of electric shock, sending a low-power operation command to the bidirectional grid-connected converter and issuing a warning message. This method achieves islanding detection and electric shock protection through harmonic feature injection, improving the reliability of collaborative protection control for integrated photovoltaic-storage-charging systems.

Description

Technical Field

[0001] This invention relates to the technical field of new energy microgrid control, and in particular to a collaborative protection control method and system for an integrated photovoltaic-storage-charging system. Background Technology

[0002] With the large-scale integration of distributed photovoltaic power generation, energy storage systems, and electric vehicle charging piles, integrated photovoltaic-energy storage-charging systems are widely used in residential courtyards, industrial parks, and other scenarios. In the event of a grid outage (i.e., islanding), if the integrated photovoltaic-energy storage-charging system fails to detect the islanding state in time and stop feeding power to the grid, it not only wastes energy but, more seriously, may cause electric shock accidents to grid maintenance personnel. Existing islanding detection technologies are mainly divided into two categories: passive (such as detecting voltage and frequency shifts) and active (such as actively injecting disturbance signals). However, both existing islanding detection methods suffer from insufficient detection safety and low detection timeliness, affecting the actual effectiveness of islanding detection. Therefore, existing islanding detection methods for integrated photovoltaic-energy storage-charging systems suffer from low detection reliability. Summary of the Invention

[0003] This invention provides a collaborative protection control method and system for an integrated photovoltaic-storage-charging system, aiming to solve the problem of low detection reliability in existing islanding detection methods for integrated photovoltaic-storage-charging systems.

[0004] In a first aspect, embodiments of the present invention provide a collaborative protection control method for an integrated photovoltaic-storage-charging system. The method is applied to a collaborative controller within a collaborative protection control system. The collaborative protection control system further includes a bidirectional grid-connected converter, a harmonic characteristic injection module, and an online impedance monitoring module. The common coupling point in the bidirectional grid-connected converter is connected to both the power grid and a DC bus. The harmonic characteristic injection module is electrically connected to the input phase line of the power grid. The common coupling point is also electrically connected to the online impedance monitoring module and a static switching switch in the bidirectional grid-connected converter. The collaborative controller is electrically connected to the harmonic characteristic injection module, the online impedance monitoring module, and the bidirectional grid-connected converter. The method includes: If a power-on signal is received, a corresponding injection control command is generated according to the preset injection parameters and sent to the harmonic feature injection module to control the harmonic feature injection module to perform harmonic injection. Send a grid-connected operation command to the static switching switch and record the command sending time; The impedance monitoring module continuously collects impedance monitoring data and parses it to obtain the corresponding impedance reference data. When the time interval between the instruction sending time and the preset time interval is reached, the impedance monitoring data is checked to see if it deviates from the impedance reference data according to the preset islanding detection rules. If the impedance reference data is deviated from, a signal blocking command and a shutdown command are sent to the bidirectional grid-connected converter; the signal blocking command is used to block the drive signal of the insulated gate bipolar transistor connected to the grid side in the bidirectional grid-connected converter, and the shutdown command is used to control the static switching switch to turn off. Send a mode switching command to the bidirectional grid-connected converter to control the bidirectional grid-connected converter to switch to the grid-type operating mode; The impedance monitoring data is monitored according to the preset electric shock risk monitoring rules to determine whether there is a risk of electric shock. If an electric shock risk is detected, a low-power operation command is sent to the bidirectional grid-connected converter and a warning message is issued.

[0005] In a second aspect, embodiments of the present invention provide a collaborative protection control system for an integrated photovoltaic-storage-charging system, wherein the collaborative controller in the collaborative protection control system applies the collaborative protection control method for an integrated photovoltaic-storage-charging system as described in the first aspect above, and the collaborative protection control system further includes a bidirectional grid-connected converter, a harmonic characteristic injection module, and an online impedance monitoring module. The DC bus is electrically connected to the photovoltaic array, the energy storage battery and the charging pile respectively. The impedance online monitoring module includes a voltage sensor, a current sensor, and an impedance online monitoring unit; The input terminals of the voltage sensor and the current sensor are respectively connected to the common coupling point, the output terminals of the voltage sensor and the current sensor are respectively connected to the input terminal of the online impedance monitoring unit, and the output terminal of the online impedance monitoring unit is connected to the input terminal of the cooperative controller.

[0006] Thirdly, embodiments of the present invention also provide a collaborative protection and control device for an integrated photovoltaic, energy storage and charging system, wherein the device includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus; Memory, used to store computer programs; When the processor executes the program stored in the memory, it implements the collaborative protection control method for the integrated optical storage and charging system as described in the first aspect above.

[0007] Fourthly, embodiments of the present invention also provide a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program that, when executed by a processor, implements the collaborative protection control method for an integrated optical storage and charging system as described in the first aspect above.

[0008] This invention provides a collaborative protection control method and system for an integrated photovoltaic-storage-charging system. The method includes: generating an injection control command and sending it to a harmonic feature injection module for harmonic injection; continuously collecting impedance monitoring data at intervals and generating impedance reference data; then, detecting whether the newly collected impedance monitoring data deviates from the impedance reference data according to islanding detection rules; if it deviates, sending a signal blocking command and a shutdown command to the bidirectional grid-connected converter; sending a mode switching command to the bidirectional grid-connected converter to switch to a grid-type operating mode and monitoring impedance monitoring data to determine if there is a risk of electric shock; if there is a risk of electric shock, sending a low-power operation command to the bidirectional grid-connected converter and issuing a warning message. This method achieves islanding detection and electric shock protection through harmonic feature injection, effectively solving the problems of blind spots in islanding detection, separation from electric shock protection functions, and voltage support gaps during switching processes, thus improving the reliability of collaborative protection control for integrated photovoltaic-storage-charging systems. Attached Figure Description

[0009] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a flowchart of a collaborative protection control method for an integrated photovoltaic, energy storage, and charging system provided in an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating an application scenario of the collaborative protection and control method for an integrated photovoltaic, energy storage, and charging system provided in this embodiment of the invention. Figure 3 The diagram illustrates the application effect of the collaborative protection and control method for an integrated photovoltaic, energy storage, and charging system provided in this embodiment of the invention. Figure 4 The illustrations show the application effects of the prior art provided in the embodiments of the present invention. Figure 5 This is a schematic diagram of the structure of the collaborative protection and control system for an integrated photovoltaic, energy storage and charging system provided in an embodiment of the present invention; Figure 6 A schematic block diagram of a computer device provided for an embodiment of the present invention. Detailed Implementation

[0011] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0013] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0014] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0015] Please see Figure 1 and Figure 2 , Figure 1 This is a flowchart of a collaborative protection and control method for an integrated photovoltaic, energy storage, and charging system provided in an embodiment of the present invention. Figure 2This is a schematic diagram illustrating an application scenario of the collaborative protection control method for an integrated photovoltaic-storage-charging system provided in an embodiment of the present invention. The collaborative protection control method for an integrated photovoltaic-storage-charging system is applied to the collaborative controller 10 of a collaborative protection control system 100. The collaborative protection control system 100 further includes a bidirectional grid-connected converter 20, a harmonic characteristic injection module 30, and an online impedance monitoring module 40. The common coupling point 21 in the bidirectional grid-connected converter 20 is connected to the power grid 50 and the DC bus 60, respectively. The harmonic characteristic injection module 30 is electrically connected to the input phase line of the power grid 50. The common coupling point 21 is also electrically connected to the online impedance monitoring module 40 and the static switching switch 22 in the bidirectional grid-connected converter 20. The collaborative controller 10 is electrically connected to the harmonic characteristic injection module 30, the online impedance monitoring module 40, and the bidirectional grid-connected converter 20. The collaborative protection and control method for the integrated photovoltaic-storage-charging system is executed by application software installed in the collaborative controller 10. The collaborative controller 10 is the terminal device used to execute the collaborative protection and control method for the integrated photovoltaic-storage-charging system, receiving impedance monitoring data collected by the bidirectional grid-connected converter 20 and performing collaborative protection and control. The collaborative controller 10 can be an MCU control chip, FPGA logic circuit, etc. Figure 1 As shown, the method includes steps S110 to S180.

[0016] S110. If a power-on signal is received, a corresponding injection control command is generated according to the preset injection parameters and sent to the harmonic feature injection module to control the harmonic feature injection module to perform harmonic injection.

[0017] The user can input a power-on signal by closing the main gate or pressing the start button. Upon receiving the power-on signal, the coordinated controller 10 generates a corresponding injection control command based on pre-set injection parameters and sends this command to the harmonic characteristic injection module. This controls the harmonic characteristic injection module to inject harmonics into the input phase line. For example, the injection parameters include the harmonic injection frequency and the injection current amplitude. The injection control command can then be generated based on the determined injection parameters, and this command controls the harmonic characteristic injection module to generate harmonics according to the injection parameters and inject them into the input phase line of the AC power grid.

[0018] In one embodiment, before step S110, the method further includes the step of configuring parameters for the input power grid characteristic information according to a preset injection configuration strategy, so as to obtain injection parameters that match the power grid characteristic information.

[0019] Furthermore, users can directly input grid characteristic information, and the collaborative controller can then obtain injection parameters that match the grid characteristic information according to the injection configuration strategy. Specifically, grid characteristic information refers to information used to characterize the current AC grid characteristics, including AC frequency (e.g., 50Hz) and rated current (e.g., 5A). The injection configuration strategy is the strategy information for parameter configuration based on the grid characteristic information. The injection configuration strategy includes harmonic ratio range and current amplitude ratio. The harmonic injection frequency can be configured according to the harmonic ratio range and AC frequency, and the injection current amplitude can be configured according to the current amplitude ratio and rated current.

[0020] If the harmonic ratio range is 11.8-14.8 and is not an integer, then the non-integer value within this range can be obtained and multiplied by the AC frequency to obtain the corresponding harmonic injection frequency. For example, if the non-integer value of 14.8 is determined and multiplied by the AC frequency of 50Hz, the corresponding harmonic injection frequency can be determined to be 740Hz. Further, the current amplitude ratio is multiplied by the rated current to obtain the corresponding injection current amplitude. For example, if the current amplitude ratio is 2%, then 2% × the rated current of 5A yields 0.1A, which can be configured as the injection current amplitude. The obtained harmonic injection frequency and injection current amplitude are combined as the corresponding injection parameters for use.

[0021] S120. Send a grid-connected operation command to the static switching switch and record the command sending time.

[0022] When a grid-connected operation command is sent to the static switching switch, the static switching switch connects the AC input phase line to the DC bus, at which point the integrated photovoltaic-storage-charging system achieves grid-connected operation. The time of sending the current grid-connected operation command is recorded as the command sending time.

[0023] S130: Receive the impedance monitoring data continuously collected by the online impedance monitoring module and parse it to obtain the corresponding impedance reference data.

[0024] The online impedance monitoring module continuously monitors the common coupling point, thereby collecting impedance monitoring data and sending it to the collaborative controller. The collaborative controller receives the impedance monitoring data, parses it, and obtains the impedance reference data.

[0025] In one embodiment, step S130 specifically includes the following sub-steps: obtaining the impedance values ​​at each acquisition time point in the impedance monitoring data and calculating the average value as the corresponding impedance baseline value; obtaining the difference between the impedance values ​​at each acquisition time point in the impedance monitoring data and the impedance baseline value to obtain the corresponding impedance fluctuation range; and combining the impedance baseline value and the impedance fluctuation range to obtain the corresponding impedance reference data.

[0026] The impedance values ​​at each acquisition point in the impedance monitoring data are obtained and their average values ​​are calculated to obtain the impedance baseline value. The acquired impedance monitoring data includes the voltage harmonic component U, extracted from the grid connection point voltage and corresponding to the harmonic injection frequency. inj The corresponding real-time impedance value is: Z sys (t) represents the impedance value at time t, U inj (t) represents the voltage harmonic component at time t, I inj To determine the injected current amplitude, the average impedance value at each acquisition point is calculated and used as the impedance baseline. For example, the calculated impedance baseline value is 0.25 ohms.

[0027] Furthermore, the difference between the impedance value at each acquisition point and the impedance baseline value is obtained, and the maximum difference is taken as the impedance fluctuation range. For example, if the maximum difference is 0.05 ohms, the corresponding fluctuation range is determined to be ±0.05 ohms.

[0028] The obtained impedance baseline value is combined with the impedance fluctuation range to obtain the corresponding impedance reference data. If impedance monitoring data is continuously received during this process, the currently obtained impedance reference data is continuously updated until the condition for executing step S140 is triggered.

[0029] S140. When the time point reaches the preset interval time of the instruction transmission time interval, detect whether the impedance monitoring data deviates from the impedance reference data according to the preset islanding detection rules.

[0030] If the preset interval between command transmission times is reached, the impedance monitoring data is checked to see if it deviates from the impedance reference data. For example, the interval can be set to 5 minutes, in which case the impedance reference data will be continuously updated within 5 minutes. Figure 3 The time interval from t0 to t1 corresponds to the time when the impedance reference data is updated. When the time interval between the instruction and the time interval is 5 minutes, the update of the impedance reference data stops and the newly acquired impedance monitoring data is checked according to the islanding detection rule to see if it deviates from the established impedance reference data. That is, starting from time t1, the detection of whether the newly acquired impedance monitoring data deviates from the impedance reference data is performed.

[0031] In one embodiment, step S140 specifically includes the following sub-steps: obtaining the impedance change rate between the current acquisition time point and the previous acquisition time point in the impedance monitoring data; determining whether the impedance change rate exceeds the change rate threshold in the islanding detection rule; if the impedance change rate exceeds the change rate threshold, determining whether the deviation ratio between the impedance value at the current acquisition time point and the impedance reference data exceeds the ratio threshold in the islanding detection rule; if the deviation ratio exceeds the ratio threshold, determining that the impedance monitoring data deviates from the impedance reference data; if the impedance change rate does not exceed the change rate threshold or the deviation ratio does not exceed the ratio threshold, determining that the impedance monitoring data does not deviate from the impedance reference data.

[0032] Specifically, the impedance change rate between the current acquisition time point and the previous acquisition time point can be obtained from the newly acquired impedance monitoring data. The impedance change rate can be expressed as dZ / dt. For example, if the interval between adjacent acquisition time points is 1 / 1000 second, and the impedance difference between the current acquisition time point and the previous acquisition time point is 0.3 ohms, then the corresponding impedance change rate is 300 ohms / second. It can be determined whether the impedance change rate exceeds the change rate threshold, such as setting the change rate threshold to 800 ohms / second.

[0033] If the rate of change of impedance exceeds the rate of change threshold, it is further determined whether the deviation ratio between the impedance value at the current acquisition time and the impedance reference data exceeds the ratio threshold set in the islanding detection rule. This can be achieved by calculating the difference between the impedance value at the current acquisition time and the upper (or lower) limit of the range in the impedance reference data, and then calculating the ratio of this difference to the impedance baseline value in the impedance reference data to obtain the deviation ratio. The islanding detection rule sets a ratio threshold, such as 50%; it can then be determined whether the obtained deviation ratio exceeds this ratio threshold.

[0034] If the deviation ratio exceeds the threshold, the impedance monitoring data is determined to deviate from the impedance reference data. If the impedance change rate does not exceed the change rate threshold, or the deviation ratio does not exceed the ratio threshold, the impedance monitoring data is determined not to deviate from the impedance reference data.

[0035] S150. If the impedance reference data is deviated, a signal blocking command and a shutdown command are sent to the bidirectional grid-connected converter. The signal blocking command is used to block the drive signal of the insulated gate bipolar transistor connected to the grid side in the bidirectional grid-connected converter, and the shutdown command is used to control the static switching switch to turn off.

[0036] For example, in Figure 3At time t2, if the impedance monitoring data deviates from the impedance reference data, it indicates that the integrated photovoltaic-storage system is in an islanded state. If it deviates from the impedance reference data, a signal blocking command and a shutdown command can be sent to the bidirectional grid-connected converter. The signal blocking command achieves electrical isolation; upon receiving the signal blocking command, the bidirectional grid-connected converter immediately blocks the drive signals of the insulated gate bipolar transistors (IGBTs) connected to the grid side. The shutdown command controls the static switching switch; upon receiving the shutdown command, the control static switch in the bidirectional grid-connected converter completes physical disconnection within 5ms, cutting off the connection path to the grid and ground to eliminate the risk of backfeeding.

[0037] S160. Send a mode switching command to the bidirectional grid-connected converter to control the bidirectional grid-connected converter to switch to the grid-type working mode.

[0038] Furthermore, a mode switching command is sent to the bidirectional grid-connected converter, thereby controlling the bidirectional grid-connected converter to switch its operating mode. Upon receiving the mode switching command, the bidirectional grid-connected converter switches its operating mode from "grid-following" to "grid-forming". After completing the mode switching, the bidirectional grid-connected converter uses the energy from the energy storage battery to supply power. At this time, a stable voltage and frequency reference (such as 220V / 50Hz) is immediately established on the user-side bus (DC bus) to continuously supply power to the charging pile and critical loads.

[0039] S170. Monitor the impedance monitoring data according to the preset electric shock risk monitoring rules to determine whether there is an electric shock risk.

[0040] After the bidirectional grid-connected converter completes its operating mode switch, the integrated photovoltaic and energy storage system enters off-grid operation. At this time, the latest impedance monitoring data can be monitored according to the electric shock risk monitoring rules to determine whether there is a risk of electric shock.

[0041] In one embodiment, step S170 specifically includes the following sub-steps: extracting the corresponding arc feature component from the impedance monitoring data according to the arc component extraction parameters in the electric shock risk monitoring rules; determining whether the arc feature component conforms to the monitoring parameters in the electric shock risk monitoring rules, so as to determine whether an electric shock risk has occurred.

[0042] Specifically, the arc characteristic component can first be extracted from the impedance monitoring data according to the arc component extraction parameters in the electric shock risk monitoring rules. The arc characteristic component is used to reflect the abnormal characteristics of the arc in the impedance value. Then, it is determined whether the arc characteristic component meets the monitoring parameters in the electric shock risk monitoring rules. If it meets the detection parameters, it is determined that there is an electric shock risk; if it does not meet the monitoring parameters, it is determined that there is no electric shock risk.

[0043] In one embodiment, the step of extracting the corresponding arc feature component from the impedance monitoring data according to the arc component extraction parameters in the electric shock risk monitoring rules includes: determining whether the impedance value in the impedance monitoring data is located within a preset oscillation interval; if the impedance value is located within the oscillation interval, performing a fast Fourier transform on the impedance value located within the oscillation interval to obtain the corresponding frequency domain transform signal; and obtaining the noise energy corresponding to the frequency range from the frequency domain transform signal as the corresponding arc feature component according to the frequency range in the arc component extraction parameters.

[0044] Specifically, it can be determined whether the impedance value in the impedance monitoring data is within a preset oscillation range, such as 0.3Ω to 0.8Ω. If the impedance value is within this oscillation range, the impedance values ​​within this oscillation range for a certain period of time (e.g., 10 seconds) are extracted and time-series arranged to obtain an impedance time-series curve. The resulting impedance time-series curve is as follows: Figure 3 The curves from time t3 to t4 are shown. A Fast Fourier Transform (FFT) is performed on the obtained impedance time-series curve to obtain the frequency-domain transformed signal corresponding to the impedance time-series curve. Based on the frequency range in the arc component extraction parameters, the noise energy corresponding to that frequency range can be extracted from the frequency-domain transformed signal. For example, the frequency range can be set to 2kHz~10kHz, and the amplitudes of each frequency point within this frequency range in the frequency-domain transformed signal can be obtained and accumulated to calculate the corresponding noise energy. This noise energy is the obtained arc characteristic component.

[0045] The electric shock risk monitoring rules include monitoring parameters such as a baseline energy value and an energy amplification threshold. First, the energy amplification of the arc characteristic component relative to the baseline energy value is calculated. The difference between the arc characteristic component and the baseline energy value is then calculated and divided by the baseline energy value to obtain the energy amplification. Further, it is determined whether the energy amplification exceeds the energy amplification threshold, which can be set to 300%. If the energy amplification threshold is exceeded, the monitoring parameters are considered met, indicating an electric shock risk. If the energy amplification threshold is not exceeded, the monitoring parameters are not met, indicating no electric shock risk.

[0046] In one embodiment, after step S170, the method further includes the following steps: if it is determined that there is no risk of electric shock, determine whether the impedance value in the impedance monitoring data is greater than a preset impedance threshold; if it is greater than the impedance threshold, determine that the load is physically disconnected.

[0047] If the judgment result is that there is no risk of electric shock, then it is further judged whether the impedance value in the impedance monitoring data is greater than the preset impedance threshold, such as the impedance threshold can be set to 100 ohms; if it is greater than the impedance threshold, it indicates that the impedance suddenly becomes infinite (voltage harmonic components return to zero), and it is judged as normal gun removal (physical load disconnection); the co-controller sends a disconnection control command to the charging pile contactor to control the charging pile contactor to disconnect and end the charging process.

[0048] If the impedance value is not greater than the preset impedance threshold and the impedance value does not deviate from the impedance reference data (the impedance value is stable within the impedance reference data), then the photovoltaic-storage-charging integrated system is considered to be working normally and maintaining normal charging.

[0049] S180. If an electric shock risk is determined, a low-power operation command is sent to the bidirectional grid-connected converter and a warning message is issued.

[0050] If an electric shock risk is detected (i.e., an abnormal arc fault occurs on the DC bus side), the coordinating controller sends a low-power operation command to the bidirectional grid-connected converter. At this time, the bidirectional grid-connected converter operates in low-power mode (e.g., the charging power is reduced from 7kW to less than 1kW). At the same time, a warning message is issued, such as pushing a warning message to the user's mobile APP that "the charging interface is abnormal, please unplug and plug it again".

[0051] The voltage changes during the execution of this embodiment and the voltage changes in the conventional solution were monitored, and the monitoring results are as follows: Figure 4 As shown, in Figure 4 When the power grid fails at time t0, the embodiments of this application can perform seamless switching without voltage drop during the switching process, which does not affect normal charging. However, traditional solutions have detection blind spots and switching lag, resulting in voltage gaps that affect normal charging.

[0052] The collaborative protection and control method for an integrated photovoltaic-storage-charging system provided in this embodiment of the invention includes: generating an injection control command and sending it to a harmonic feature injection module for harmonic injection; continuously collecting impedance monitoring data within an interval and generating impedance reference data; then detecting whether the newly collected impedance monitoring data deviates from the impedance reference data according to islanding detection rules; if it deviates from the impedance reference data, sending a signal blocking command and a shutdown command to the bidirectional grid-connected converter; sending a mode switching command to the bidirectional grid-connected converter to switch to a grid-type operating mode and monitoring impedance monitoring data to determine whether there is a risk of electric shock; if there is a risk of electric shock, sending a low-power operation command to the bidirectional grid-connected converter and issuing a warning message. This method achieves islanding detection and electric shock protection through harmonic feature injection, effectively solving the problems of blind spots in islanding detection, separation from electric shock protection functions, and voltage support gaps during switching processes, thus improving the reliability of collaborative protection and control for integrated photovoltaic-storage-charging systems.

[0053] This invention also provides a collaborative protection control system for an integrated photovoltaic-storage-charging system. This collaborative protection control system can be configured in the collaborative controller 10 of a collaborative protection control system 100. The collaborative protection control system 100 further includes a bidirectional grid-connected converter 20, a harmonic characteristic injection module 30, and an online impedance monitoring module 40. The common coupling point 21 of the bidirectional grid-connected converter 20 is connected to the power grid 50 and the DC bus 60, respectively. The harmonic characteristic injection module 30 is electrically connected to the input phase line of the power grid 50. The common coupling point 21 is also electrically connected to the online impedance monitoring module 40 and the static switching switch 22 in the bidirectional grid-connected converter 20. The collaborative controller 10 is electrically connected to the harmonic characteristic injection module 30, the online impedance monitoring module 40, and the bidirectional grid-connected converter 20. The collaborative controller 10 in this collaborative protection control system for the integrated photovoltaic-storage-charging system is used to execute any embodiment of the aforementioned collaborative protection control method for the integrated photovoltaic-storage-charging system. Specifically, please refer to... Figure 5 , Figure 5 This is a schematic diagram of the structure of the collaborative protection and control system for an integrated photovoltaic, energy storage and charging system provided in an embodiment of the present invention.

[0054] like Figure 5 As shown, the collaborative protection and control system 100 for the photovoltaic-storage-charging integrated system includes a collaborative controller 10, a bidirectional grid-connected converter 20, a harmonic characteristic injection module 30, and an impedance online monitoring module 40. The DC bus 60 is electrically connected to the photovoltaic array 61, the energy storage battery 62, and the charging pile 63, respectively. The impedance online monitoring module 40 includes a voltage sensor 41, a current sensor 42, and an impedance online monitoring unit 43. The input terminals of the voltage sensor 41 and the current sensor 42 are respectively connected to the common coupling point 21, and the output terminals of the voltage sensor 41 and the current sensor 42 are respectively connected to the input terminal of the impedance online monitoring unit 43. The output terminal of the impedance online monitoring unit 43 is connected to the input terminal of the cooperative controller 10.

[0055] The collaborative protection control system for an integrated photovoltaic-storage-charging system provided in this embodiment of the invention applies the aforementioned collaborative protection control method for such systems. The method includes: generating an injection control command and sending it to a harmonic feature injection module for harmonic injection; continuously collecting impedance monitoring data within an interval and generating impedance reference data; then detecting whether the newly collected impedance monitoring data deviates from the impedance reference data according to islanding detection rules; if it deviates, sending a signal blocking command and a shutdown command to the bidirectional grid-connected converter; sending a mode switching command to the bidirectional grid-connected converter to switch to a grid-type operating mode and monitoring impedance monitoring data to determine if there is a risk of electric shock; if there is a risk of electric shock, sending a low-power operation command to the bidirectional grid-connected converter and issuing a warning message. This method achieves islanding detection and electric shock protection through harmonic feature injection, effectively solving the problems of blind spots in islanding detection, separation from electric shock protection functions, and voltage support gaps during switching processes, thus improving the reliability of collaborative protection control for integrated photovoltaic-storage-charging systems.

[0056] The collaborative controller in the aforementioned collaborative protection and control system for the integrated photovoltaic-storage-charging system can be implemented as a computer program. This computer program can be used in various ways, such as... Figure 6 The computer device shown runs on the computer. The computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor; when the computer device executes the computer program, it implements the collaborative protection control method for the integrated photovoltaic storage and charging system as described in the above embodiments.

[0057] Please see Figure 6 , Figure 6 This is a schematic block diagram of a computer device provided in an embodiment of the present invention. The computer device can be a terminal device used to execute a collaborative protection control method for an integrated photovoltaic-storage-charging system, receiving impedance monitoring data collected by the bidirectional grid-connected converter 20 and performing collaborative protection control.

[0058] See Figure 6 The computer device 500 includes a processor 502, a memory, and a communication interface 505 connected via a system bus 501. The memory may include a storage medium 503 and internal memory 504.

[0059] The storage medium 503 may store an operating system 5031 and a computer program 5032. When the computer program 5032 is executed, it causes the processor 502 to execute a collaborative protection control method for the integrated optical storage and charging system. The storage medium 503 may be a volatile storage medium or a non-volatile storage medium.

[0060] The processor 502 provides computing and control capabilities to support the operation of the entire computer device 500.

[0061] The internal memory 504 provides an environment for the operation of the computer program 5032 in the storage medium 503. When the computer program 5032 is executed by the processor 502, the processor 502 can execute a collaborative protection control method for the integrated optical storage and charging system.

[0062] This communication interface 505 is used for network communication, such as providing data transmission. Those skilled in the art will understand that... Figure 6 The structure shown is merely a block diagram of a portion of the structure related to the present invention and does not constitute a limitation on the computer device 500 to which the present invention is applied. The specific computer device 500 may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0063] The processor 502 is used to run the computer program 5032 stored in the memory to implement the corresponding functions in the above-mentioned collaborative protection and control method for the integrated optical storage and charging system.

[0064] Those skilled in the art will understand that Figure 6 The embodiments of the computer device shown do not constitute a limitation on the specific configuration of the computer device. In other embodiments, the computer device may include more or fewer components than illustrated, or combine certain components, or have different component arrangements. For example, in some embodiments, the computer device may include only memory and a processor. In such embodiments, the structure and function of the memory and processor are different from those shown. Figure 6 The embodiments shown are consistent and will not be described again here.

[0065] It should be understood that, in this embodiment of the invention, the processor 502 may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0066] In another embodiment of the invention, a computer-readable storage medium is provided. This computer-readable storage medium may be volatile or non-volatile. The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps included in the above-described collaborative protection control method for an integrated optical storage and charging system.

[0067] Those skilled in the art will readily understand that, for the sake of convenience and brevity, the specific working processes of the devices, apparatuses, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention.

[0068] In the embodiments provided by this invention, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Units with the same function may be grouped into one unit. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interfaces, devices, or units, or it may be an electrical, mechanical, or other form of connection.

[0069] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention, depending on actual needs.

[0070] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0071] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a computer-readable storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned computer-readable storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), magnetic disks, or optical disks.

[0072] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for cooperative protection control of a photovoltaic energy storage and charging integrated system, characterized in that, The method is applied to the collaborative controller of a collaborative protection control system. The collaborative protection control system further includes a bidirectional grid-connected converter, a harmonic characteristic injection module, and an online impedance monitoring module. The common coupling point in the bidirectional grid-connected converter is connected to both the power grid and the DC bus. The harmonic characteristic injection module is electrically connected to the input phase line of the power grid. The common coupling point is also electrically connected to the online impedance monitoring module and the static switching switch in the bidirectional grid-connected converter. The collaborative controller is electrically connected to the harmonic characteristic injection module, the online impedance monitoring module, and the bidirectional grid-connected converter. The method includes: If a power-on signal is received, a corresponding injection control command is generated according to the preset injection parameters and sent to the harmonic feature injection module to control the harmonic feature injection module to perform harmonic injection. Send a grid-connected operation command to the static switching switch and record the command sending time; The impedance monitoring module continuously collects impedance monitoring data and parses it to obtain the corresponding impedance reference data. When the time interval between the instruction sending time and the preset time interval is reached, the impedance monitoring data is checked to see if it deviates from the impedance reference data according to the preset islanding detection rules. If the impedance reference data is deviated from, a signal blocking command and a shutdown command are sent to the bidirectional grid-connected converter; the signal blocking command is used to block the drive signal of the insulated gate bipolar transistor connected to the grid side in the bidirectional grid-connected converter, and the shutdown command is used to control the static switching switch to turn off. Send a mode switching command to the bidirectional grid-connected converter to control the bidirectional grid-connected converter to switch to the grid-type operating mode; The impedance monitoring data is monitored according to the preset electric shock risk monitoring rules to determine whether there is a risk of electric shock. If an electric shock risk is detected, a low-power operation command is sent to the bidirectional grid-connected converter and a warning message is issued. 2.The method for cooperative protection control of a light storage and charging integrated system according to claim 1, wherein, The process of receiving impedance monitoring data acquired by the online impedance monitoring module and parsing it to obtain the corresponding impedance reference data includes: Obtain the impedance values ​​at each acquisition time point in the impedance monitoring data and calculate the average value as the corresponding impedance baseline value; The difference between the impedance value at each acquisition time point in the impedance monitoring data and the impedance baseline value is obtained to obtain the corresponding impedance fluctuation range; The impedance baseline value is combined with the impedance fluctuation range to obtain the corresponding impedance reference data. 3.The method for synergic protection control of optical storage and charging integrated system according to claim 2, characterized in that, The step of detecting whether the impedance monitoring data deviates from the impedance reference data according to the preset islanding detection rules includes: Obtain the rate of change of impedance between the current acquisition time and the previous acquisition time in the impedance monitoring data; Determine whether the impedance change rate exceeds the change rate threshold in the island detection rule; If the impedance change rate exceeds the change rate threshold, determine whether the deviation ratio between the impedance value at the current acquisition time point and the impedance reference data exceeds the ratio threshold in the island detection rule. If the deviation ratio exceeds the ratio threshold, it is determined that the impedance monitoring data deviates from the impedance reference data; If the impedance change rate does not exceed the change rate threshold or the deviation ratio does not exceed the ratio threshold, it is determined that the impedance monitoring data does not deviate from the impedance reference data. 4.The method for the coordinated protection control of the optical storage and charging integrated system according to any one of claims 1-3, characterized in that, The step of monitoring the impedance monitoring data according to preset electric shock risk monitoring rules to determine whether an electric shock risk has occurred includes: According to the arc component extraction parameters in the electric shock risk monitoring rules, the corresponding arc feature components are extracted from the impedance monitoring data. Determine whether the arc characteristic components conform to the monitoring parameters in the electric shock risk monitoring rules to determine whether an electric shock risk has occurred.

5. The collaborative protection and control method for an integrated photovoltaic-storage-charging system according to claim 4, characterized in that, The step of extracting the corresponding arc feature component from the impedance monitoring data according to the arc component extraction parameters in the electric shock risk monitoring rules includes: Determine whether the impedance value in the impedance monitoring data is within a preset oscillation range; If the impedance value is located within the oscillation interval, perform a fast Fourier transform on the impedance value located within the oscillation interval to obtain the corresponding frequency domain transformed signal; Based on the frequency range in the arc component extraction parameters, noise energy corresponding to the frequency range is obtained from the frequency domain transformed signal as the corresponding arc feature component.

6. The collaborative protection and control method for an integrated photovoltaic-storage-charging system according to claim 5, characterized in that, After monitoring the impedance monitoring data according to preset electric shock risk monitoring rules to determine whether there is a risk of electric shock, the method further includes: If it is determined that there is no risk of electric shock, determine whether the impedance value in the impedance monitoring data is greater than a preset impedance threshold. If the impedance exceeds the threshold, the load is determined to be physically disconnected.

7. The collaborative protection and control method for an integrated photovoltaic-storage-charging system according to claim 4, characterized in that, Before generating corresponding injection control commands based on preset injection parameters and sending them to the harmonic feature injection module to control the harmonic feature injection module to perform harmonic injection, the method further includes: The input power grid characteristic information is configured with parameters according to a preset injection configuration strategy to obtain injection parameters that match the power grid characteristic information.

8. A collaborative protection and control system for an integrated photovoltaic-storage-charging system, characterized in that, The collaborative controller in the collaborative protection control system applies the collaborative protection control method for an integrated photovoltaic-storage-charging system as described in any one of claims 1-7. The collaborative protection control system further includes a bidirectional grid-connected converter, a harmonic characteristic injection module, and an online impedance monitoring module. The DC bus is electrically connected to the photovoltaic array, the energy storage battery and the charging pile respectively. The impedance online monitoring module includes a voltage sensor, a current sensor, and an impedance online monitoring unit; The input terminals of the voltage sensor and the current sensor are respectively connected to the common coupling point, the output terminals of the voltage sensor and the current sensor are respectively connected to the input terminal of the online impedance monitoring unit, and the output terminal of the online impedance monitoring unit is connected to the input terminal of the cooperative controller.

9. A computer device, characterized in that, The device includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; When the processor executes the program stored in the memory, it implements the collaborative protection control method for an integrated optical storage and charging system as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the collaborative protection and control method for an integrated photovoltaic, energy storage, and charging system as described in any one of claims 1 to 7.

Images