Inertia support control method and apparatus for grid-forming photovoltaic system

Abstract

An inertia support control method and apparatus for a grid-forming photovoltaic system. When a grid-forming photovoltaic system needs to be started, a VSC inversion unit can be locked, and a DC / DC boost circuit is switched to a charging mode; real-time monitoring is then performed on a direct-current bus voltage, and when the duration during which the direct-current bus voltage remains at a preset target voltage is greater than a preset target duration, the inversion unit is started, and the boost circuit is switched to a maximum power tracking mode; then, a dispatching requirement of the photovoltaic system can be acquired; and the maximum power tracking mode of the boost circuit is maintained when the dispatching requirement is that power generation takes priority, and the boost circuit is switched to a reserved active mode when the dispatching requirement is that inertia support takes priority. A VSC inversion unit and a DC / DC boost circuit are used to control a photovoltaic system, so that flexible inertia support can be realized on the basis of improving the system stability under weak power grid conditions, thereby improving the stability and reliability of a power system.

Description

Inertia support control method and device for grid-type photovoltaic system

[0001] This application claims priority to the Chinese patent application filed with the Patent Office of China on November 28, 2023, with application number 202311609857.9 and invention name “A method and device for controlling inertia support of a grid-type photovoltaic system”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of power systems, and in particular to an inertia support control method and device for a grid-connected photovoltaic system. Background Art

[0003] The proposal of the strategic goal of "carbon peak and carbon neutrality" has accelerated the process of building a new power system. The widespread access of a high proportion of new energy and the large-scale application of a high proportion of power electronic equipment will profoundly change the characteristics of the power system. The power system faces the problem of reducing the inertia level. The existing new energy converters mainly adopt the grid-following control method. Its technical characteristics are mainly to track the external grid frequency through a phase-locked loop and present a current source characteristic to the outside. Under the grid-following control method, it is necessary to adjust the power output according to the measured frequency change rate to achieve inertia support. The energy required for inertia support is usually provided by configuring energy storage. This process will cause the inertia response speed to slow down due to the measurement delay, and the phase-locked loop has poor stability when connected to a weak grid, which affects the control effect and leads to low stability and reliability of the power system.

[0004] Summary of the Invention

[0005] The purpose of this application is to solve at least one of the above-mentioned technical defects, especially the technical defect that the control method in the prior art has poor control effect, resulting in low stability and reliability of the power system.

[0006] The present application provides an inertia support control method for a grid-type photovoltaic system, wherein the grid-type photovoltaic system includes a VSC inverter unit and a DC / DC boost circuit, and the method includes:

[0007] When the grid-connected photovoltaic system needs to be started, the VSC inverter unit is locked, and the DC / DC boost circuit is switched to a charging mode based on a preset duty cycle control strategy;

[0008] monitoring the DC bus voltage in real time, and when the DC bus voltage reaches a preset target voltage for a period longer than a preset target period, starting the VSC inverter unit based on a preset grid-type control strategy, and switching the DC / DC boost circuit to a maximum power point tracking mode based on the duty cycle control strategy;

[0009] Obtaining a scheduling requirement of the grid-connected photovoltaic system, wherein the scheduling requirement includes power generation priority and inertia support priority;

[0010] When the scheduling demand is power generation priority, maintaining the maximum power tracking mode of the DC / DC boost circuit;

[0011] When the scheduling requirement is inertia support priority, the DC / DC boost circuit is switched to a reserved active power mode based on the duty cycle control strategy.

[0012] Optionally, switching the DC / DC boost circuit to a charging mode based on a preset duty cycle control strategy includes:

[0013] Obtaining an actual total voltage, a first reference total voltage, and an actual total current of the grid-type photovoltaic system;

[0014] determining a first duty cycle of the DC / DC boost circuit according to the actual total voltage, the first reference total voltage, and the actual total current;

[0015] Signal pulse width modulation is performed based on the first duty cycle to generate a first control signal, and the DC / DC boost circuit is switched to a charging mode according to the first control signal.

[0016] Optionally, the DC / DC boost circuit includes a first proportional-integral link and a second proportional-integral link;

[0017] Determining a first duty cycle of the DC / DC boost circuit according to the actual total voltage, the first reference total voltage, and the actual total current includes:

[0018] Calculating a first voltage difference between the actual total voltage and the first reference total voltage, and determining a reference total current corresponding to the first voltage difference through the first proportional integral link;

[0019] A current difference between the actual total current and the reference total current is calculated, and a first duty cycle corresponding to the current difference is determined through the second proportional-integral link.

[0020] Optionally, the VSC inverter unit includes a lead-lag link, an integral link, an AC voltage loop and a current loop;

[0021] The starting of the VSC inverter unit based on a preset grid-type control strategy includes:

[0022] Obtaining an actual total voltage and a second reference total voltage of the grid-type photovoltaic system, and calculating a second voltage difference between the actual total voltage and the second reference total voltage;

[0023] Determining a phase angle corresponding to the second voltage difference through the lead-lag link and the integral link, and determining a first reference valve-side voltage and a second reference valve-side voltage of the VSC inverter unit through the AC voltage loop and the current loop;

[0024] A switching signal is generated according to the phase angle, the first reference valve-side voltage, and the second reference valve-side voltage, and activation of the VSC inverter unit is controlled based on the switching signal.

[0025] Optionally, switching the DC / DC boost circuit to a maximum power point tracking mode based on the duty cycle control strategy includes:

[0026] Obtaining a reference output voltage, actual output current, and actual output power of a single photovoltaic string in the DC / DC boost circuit;

[0027] determining a second duty cycle of the DC / DC boost circuit according to the reference output voltage, the actual output current, and the actual output power;

[0028] Signal pulse width modulation is performed based on the second duty cycle to generate a second control signal, and the DC / DC boost circuit is switched to a maximum power point tracking mode according to the second control signal.

[0029] Optionally, the DC / DC boost circuit further includes a third proportional-integral link;

[0030] The determining the second duty cycle of the DC / DC boost circuit according to the reference output voltage, the actual output current, and the actual output power includes:

[0031] Determining a reference output power of the photovoltaic string according to the reference output voltage and the actual output current;

[0032] A first power difference between the actual output power and the reference output power is calculated, and a second duty cycle corresponding to the first power difference is determined through the third proportional integral link.

[0033] Optionally, the DC / DC boost circuit further includes a differential filtering link, a power distribution link, a limiting link and a fourth proportional integral link;

[0034] The step of switching the DC / DC boost circuit to a reserved active power mode based on the duty cycle control strategy includes:

[0035] Obtaining an actual total voltage of the grid-type photovoltaic system and a reference output power of a single photovoltaic string in the grid-type photovoltaic system;

[0036] Determining a reference inertia support power corresponding to the actual total voltage through the differential filtering link and the power distribution link, and determining a reference adjustment power corresponding to the reference output power through the limiting link;

[0037] Calculating a second power difference between the reference inertia support power and the reference adjustment power, and determining a third duty cycle corresponding to the second power difference through the fourth proportional-integral link;

[0038] Signal pulse width modulation is performed based on the third duty cycle to generate a third control signal, and the DC / DC boost circuit is switched to a maximum power point tracking mode according to the third control signal.

[0039] The present application also provides an inertia support control device, comprising:

[0040] a first control module, configured to lock the VSC inverter unit and switch the DC / DC boost circuit to a charging mode based on a preset duty cycle control strategy when the grid-connected photovoltaic system needs to be started;

[0041] a second control module, configured to monitor the DC bus voltage in real time, and after the DC bus voltage reaches a preset target voltage for a period longer than a preset target period, start the VSC inverter unit based on a preset grid-type control strategy, and switch the DC / DC boost circuit to a maximum power point tracking mode based on the duty cycle control strategy;

[0042] A demand acquisition module, configured to acquire a scheduling demand of the grid-type photovoltaic system, wherein the scheduling demand includes power generation priority and inertia support priority;

[0043] A mode maintaining module, configured to maintain a maximum power tracking mode of the DC / DC boost circuit when the scheduling demand is power generation priority;

[0044] The third control module is configured to switch the DC / DC boost circuit to a reserved active power mode based on the duty cycle control strategy when the scheduling requirement is inertia support priority.

[0045] The present application also provides a storage medium, in which computer-readable instructions are stored. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the inertia support control method as described in any of the above embodiments.

[0046] The present application also provides a computer device, comprising: one or more processors, and a memory;

[0047] The memory stores computer-readable instructions, and when the computer-readable instructions are executed by the one or more processors, the steps of the inertia support control method as described in any one of the above embodiments are performed.

[0048] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0049] The present application provides an inertia support control method and device for a grid-type photovoltaic system, which includes a VSC inverter unit and a DC / DC boost circuit. When the grid-type photovoltaic system needs to be started, the VSC inverter unit can be locked, and the DC / DC boost circuit can be switched to a charging mode based on a preset duty cycle control strategy. This allows the configured energy storage of the grid-type photovoltaic system to be smoothly charged when the grid-type photovoltaic system is started, thereby providing stable power support for the grid-type photovoltaic system when necessary. During the configured energy storage charging process, the DC bus voltage can be monitored in real time. When the DC bus voltage remains at a preset target voltage for a period longer than a preset target time, the VSC inverter unit is started based on a preset grid-type control strategy, and the DC / DC boost circuit is switched to a maximum power tracking mode based on a duty cycle control strategy. This achieves maximum power output of the photovoltaic string and improves the power generation efficiency and energy utilization of the grid-type photovoltaic system. Subsequently, a scheduling demand of the photovoltaic system can be obtained, and the grid-type photovoltaic system can be switched to a corresponding mode based on the scheduling demand. For example, when the scheduling demand is to prioritize power generation, the maximum power tracking mode of the DC / DC boost circuit can be maintained, so that the inertia support energy of the grid-type photovoltaic system is entirely derived from the energy stored in the configured energy storage; when the scheduling demand is to prioritize inertia support, the DC / DC boost circuit can be switched to a reserved active power mode based on a duty cycle control strategy, with the energy stored in the configured energy storage as the main mode and the active power reserved by the photovoltaic panels as the auxiliary mode, to provide inertia support for the grid-type photovoltaic system. This application utilizes the grid-type control strategy of the VSC inverter unit and the three control modes of the DC / DC boost circuit to coordinate control of the grid-type photovoltaic system, which can achieve flexible inertia support on the basis of improving the stability of the system under weak grid conditions, thereby improving the stability and reliability of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0051] FIG1 is a flow chart of an inertia support control method for a grid-type photovoltaic system provided in an embodiment of the present application;

[0052] FIG2 is a schematic diagram of a circuit topology of a grid-type photovoltaic system provided in an embodiment of the present application;

[0053] FIG3 is a control schematic diagram of a DC / DC boost circuit provided in an embodiment of the present application;

[0054] FIG4 is a control diagram of a DC voltage loop provided in an embodiment of the present application;

[0055] FIG5 is a flow chart of an inertial support control device for a grid-type photovoltaic system provided by an embodiment of the present application;

[0056] FIG6 is a schematic diagram of the internal structure of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0058] The proposal of the strategic goal of "carbon peak and carbon neutrality" has accelerated the process of building a new power system. The widespread access of a high proportion of new energy and the large-scale application of a high proportion of power electronic equipment will profoundly change the characteristics of the power system. The power system faces the problem of reducing the inertia level. The existing new energy converters mainly adopt the grid-following control method. Its technical characteristics are mainly to track the external grid frequency through a phase-locked loop and present a current source characteristic to the outside. Under the grid-following control method, it is necessary to adjust the power output according to the measured frequency change rate to achieve inertia support. The energy required for inertia support is usually provided by configuring energy storage. This process will cause the inertia response speed to slow down due to the measurement delay, and the phase-locked loop has poor stability when connected to a weak grid, which affects the control effect and leads to low stability and reliability of the power system.

[0059] Based on this, this application proposes the following technical solutions, please refer to the following for details:

[0060] In one embodiment, as shown in FIG1 , FIG1 is a flow chart of an inertia support control method for a grid-type photovoltaic system provided in an embodiment of the present application. The embodiment of the present application also provides an inertia support control method for a grid-type photovoltaic system, specifically including the following:

[0061] S110: When the grid-connected photovoltaic system needs to be started, the VSC inverter unit is locked, and the DC / DC boost circuit is switched to a charging mode based on a preset duty cycle control strategy.

[0062] In this step, the grid-connected PV system primarily uses the VSC inverter unit and DC / DC boost circuit for inertia support control. When the user needs to start the grid-connected PV system, they can first lock the VSC inverter unit and simultaneously switch the DC / DC boost circuit to charging mode based on a preset duty cycle control strategy.

[0063] Among them, the grid-type photovoltaic system refers to a system that converts solar energy into electrical energy through a grid-type control method. Among them, the grid-type control refers to a closed-loop control method based on DC voltage control, which maintains synchronization with the external power grid through a power synchronization mechanism similar to a synchronous generator, and does not require a phase-locked loop during normal control.

[0064] Schematically, as shown in Figure 2, Figure 2 is a structural diagram of the circuit topology of a grid-type photovoltaic system provided in an embodiment of the present application; in Figure 2, the grid-type photovoltaic system can be composed of a photovoltaic string, a DC / DC boost circuit, a DC bus, a VSC inverter unit and an AC filter.

[0065] Specifically, a photovoltaic string refers to a series circuit consisting of several photovoltaic cells that can convert solar energy into direct current (DC). In a grid-type photovoltaic system, a photovoltaic string is typically composed of several connected strings to increase voltage and power. A DC / DC boost circuit is a circuit used to increase the DC voltage of a photovoltaic string to the DC voltage required by the inverter. In a grid-type photovoltaic system, this DC / DC boost circuit typically uses maximum power point tracking (MPPT) technology to achieve maximum power output from the photovoltaic string. A DC bus is a DC circuit used to connect the photovoltaic string and the VSC inverter unit, which can transmit the DC voltage of the photovoltaic string to the inverter. In a grid-type photovoltaic system, the DC bus must have sufficient voltage and current capabilities to ensure stable system operation. A VSC inverter unit is an inverter used to convert DC power into AC power. In a grid-type photovoltaic system, the VSC inverter unit is controlled by a controller to achieve power and stability control of the system. An AC filter is a filter used to filter out high-frequency noise and harmonics output by the inverter. In a grid-type photovoltaic system, the AC filter must have sufficient filtering effect to ensure the electromagnetic compatibility and stability of the system.

[0066] It is understandable that when a user needs to start a grid-connected photovoltaic system, the VSC inverter unit can be locked first. In this way, the grid-connected photovoltaic system will not output power, thereby preventing abnormal conditions such as overvoltage or overcurrent during the startup process of the grid-connected photovoltaic system, thereby ensuring the safe and stable operation of the grid-connected photovoltaic system. When the DC / DC boost circuit switches to charging mode, the DC side capacitor can be used as the configuration energy storage in the grid-connected photovoltaic system to store electrical energy, thereby providing stable power support to the power system when needed, thereby improving the stability and reliability of the power system.

[0067] S120: The DC bus voltage is monitored in real time, and when the time for the DC bus voltage to reach a preset target voltage is longer than the preset target time, the VSC inverter unit is started based on the preset grid control strategy, and the DC / DC boost circuit is switched to the maximum power tracking mode based on the duty cycle control strategy.

[0068] In this step, after the DC / DC boost circuit is switched to the charging mode through step S110, the voltage of the DC bus can be monitored in real time, and timing starts when the DC bus voltage rises to the preset target voltage. When the time duration exceeds the preset target time duration, the VSC inverter unit is started based on the preset grid-type control strategy, and the DC / DC boost circuit is switched to the maximum power tracking mode based on the duty cycle control strategy.

[0069] Among them, the preset grid-type control strategy refers to a control strategy for a grid-type photovoltaic system, which realizes power control and stability control of the grid-type photovoltaic system by controlling parameters such as the output power and voltage of the VSC inverter; and the duty cycle control strategy refers to a control strategy for the output voltage and frequency by adjusting the duty cycle of the output waveform of the VSC inverter, thereby realizing power control and stability control of the grid-type photovoltaic system. In addition, the maximum power tracking mode in this application refers to a control mode for a grid-type photovoltaic system, which can realize the maximum power output of the grid-type photovoltaic system. In the maximum power tracking mode, the grid-type photovoltaic system will maximize the output power of the photovoltaic panel by continuously adjusting the output voltage and current, thereby realizing the maximum power output of the grid-type photovoltaic system.

[0070] Specifically, when starting the grid-type photovoltaic system, the preset target voltage and preset target duration of the grid-type photovoltaic system can be obtained first, where the preset target voltage refers to the target value reached by the DC bus voltage, and the preset target duration refers to the length of time that the DC bus needs to maintain after reaching the preset target voltage; after the DC / DC boost circuit switches to charging mode, it is necessary to monitor the DC bus voltage in real time, and when the DC bus voltage reaches the preset target voltage, start timing to record the time when the DC bus reaches the preset target voltage. At the same time, it can be determined whether the time is greater than the preset target duration. If it is greater, it means that the DC side capacitor is fully charged, and charging needs to be stopped at this time to avoid overcharging.

[0071] S130: Obtaining the scheduling requirements of the grid-connected photovoltaic system.

[0072] In this step, after starting the VSC inverter and switching the DC / DC boost circuit to the maximum power tracking mode in step S120, the scheduling requirements of the grid-connected photovoltaic system can be obtained, and then the mode of the DC / DC boost circuit can be switched according to the scheduling requirements.

[0073] It can be understood that the scheduling requirements include power generation priority and inertia support priority. Among them, power generation priority refers to the grid-type photovoltaic system giving priority to the power output of photovoltaic power generation during the power supply process; specifically, when the power generation power of the grid-type photovoltaic system is greater than the load demand, the excess power can be injected into the power system to improve the power supply capacity and reliability of the power system; when the power generation power of the grid-type photovoltaic system is less than the load demand, it can be supplemented by configuring energy storage and other methods to meet the load demand of the power system. Inertia support priority refers to the grid-type photovoltaic system giving priority to the stability and reliability of the power system during the power supply process; specifically, when the power system has abnormal conditions such as overvoltage or overcurrent, the grid-type photovoltaic system needs to adjust the power output in time to ensure the stable operation of the power system; in addition, when the power system has load fluctuations or short power outages, the grid-type photovoltaic system can provide stable power support to the power system through inertia support technology to improve the reliability and stability of the power system. Therefore, the present application can realize flexible inertia support according to the scheduling requirements of the grid-type photovoltaic system.

[0074] S140: When the scheduling demand is power generation priority, maintain the maximum power tracking mode of the DC / DC boost circuit.

[0075] In this step, after obtaining the scheduling requirements of the grid-connected photovoltaic system in step S130, the type of the scheduling requirements can be determined. When the scheduling requirements are power generation priority, the maximum power tracking mode of the DC / DC boost circuit can be maintained.

[0076] Understandably, when the dispatching demand prioritizes power generation, the primary goal of the grid-connected PV system is to maximize power output to meet the load demands of the power system. In this case, the DC / DC boost circuit must maintain its maximum power output tracking (MPPT) mode to achieve the maximum power output of the grid-connected PV system. Specifically, MPPT adjusts the output voltage and current in real time based on factors such as light intensity and temperature, maximizing the output power of the PV panels and improving the power generation efficiency and energy utilization of the grid-connected PV system.

[0077] Furthermore, the maximum power point tracking (MPPT) mode of the DC / DC boost circuit can enhance the adaptability and flexibility of grid-connected PV systems. As lighting conditions or load demands change, MPPT adjusts the output voltage and current in real time to match the maximum power output of the grid-connected PV system with the load demands of the power system. This improves the adaptability and flexibility of the grid-connected PV system, ensuring stable operation of the grid-connected PV system and stable power supply to the power system.

[0078] S150: When the scheduling requirement is inertia support priority, the DC / DC boost circuit is switched to a reserved active power mode based on a duty cycle control strategy.

[0079] In this step, after obtaining the scheduling requirements of the grid-connected photovoltaic system in step S130, the type of the scheduling requirements can be determined. When the scheduling requirements are inertia support priority, the DC / DC boost circuit can be switched to the reserved active power mode based on the duty cycle control strategy.

[0080] It is understandable that when the dispatch demand prioritizes inertia support, the main goal of the grid-connected photovoltaic system is to ensure the stability and reliability of the power system. In this case, the DC / DC boost circuit can be switched to the reserved active power mode to provide stable active power support and ensure the stable operation of the power system. Specifically, the output power and voltage parameters of the VSC inverter can be adjusted based on the duty cycle control strategy, and the DC / DC boost circuit can be switched to the reserved active power mode to achieve active power output control of the power system. In the reserved active power mode, the grid-connected photovoltaic system can reserve a portion of power for stability support of the power system to ensure the stable operation of the power system. When the power system experiences load fluctuations or short power outages, the grid-connected photovoltaic system can provide stable active power support to the power system through reserved active power technology, thereby improving the reliability and stability of the power system.

[0081] Furthermore, the DC / DC boost circuit's reserve active power mode enhances the adaptability and flexibility of grid-connected PV systems. In the event of load fluctuations or brief power outages in the power system, the reserve active power mode allows real-time adjustment of output power and voltage to meet the power system's load demands and stability requirements, thereby improving the adaptability and flexibility of the grid-connected PV system and ensuring its stable operation and power supply.

[0082] In the above embodiment, the grid-type photovoltaic system includes a VSC inverter unit and a DC / DC boost circuit. When the grid-type photovoltaic system needs to be started, the VSC inverter unit can be locked, and the DC / DC boost circuit can be switched to a charging mode based on a preset duty cycle control strategy. This allows the configured energy storage of the grid-type photovoltaic system to be smoothly charged when the grid-type photovoltaic system is started, thereby providing stable power support for the grid-type photovoltaic system when necessary. During the configured energy storage charging process, the DC bus voltage can be monitored in real time. When the DC bus voltage remains at a preset target voltage for a period longer than a preset target time, the VSC inverter unit is started based on a preset grid-type control strategy, and the DC / DC boost circuit is switched to a maximum power tracking mode based on a duty cycle control strategy. This achieves maximum power output of the photovoltaic string and improves the power generation efficiency and energy utilization of the grid-type photovoltaic system. Subsequently, a scheduling demand of the photovoltaic system can be obtained, and the grid-type photovoltaic system can be switched to a corresponding mode based on the scheduling demand. For example, when the scheduling demand is to prioritize power generation, the maximum power tracking mode of the DC / DC boost circuit can be maintained, so that the inertia support energy of the grid-type photovoltaic system is entirely derived from the energy stored in the configured energy storage; when the scheduling demand is to prioritize inertia support, the DC / DC boost circuit can be switched to a reserved active power mode based on a duty cycle control strategy, with the energy stored in the configured energy storage as the main mode and the active power reserved by the photovoltaic panels as the auxiliary mode, to provide inertia support for the grid-type photovoltaic system. This application utilizes the grid-type control strategy of the VSC inverter unit and the three control modes of the DC / DC boost circuit to coordinate control of the grid-type photovoltaic system, which can achieve flexible inertia support on the basis of improving the stability of the system under weak grid conditions, thereby improving the stability and reliability of the power system.

[0083] In one embodiment, switching the DC / DC boost circuit to the charging mode based on a preset duty cycle control strategy in step S110 may include:

[0084] S111: Acquire an actual total voltage, a first reference total voltage, and an actual total current of a grid-connected photovoltaic system.

[0085] S112: Determine a first duty cycle of the DC / DC boost circuit according to the actual total voltage, the first reference total voltage, and the actual total current.

[0086] S113: Performing pulse width modulation on the signal based on the first duty cycle to generate a first control signal, and switching the DC / DC boost circuit to a charging mode according to the first control signal.

[0087] In this embodiment, when the DC / DC boost circuit needs to be switched to the charging mode, the actual total voltage, the first reference total voltage and the actual total current of the VSC inverter unit can be obtained first, and the first duty cycle of the DC / DC boost circuit can be determined based on the actual total voltage, the first reference total voltage and the actual total current. Then, the signal pulse width modulation can be performed based on the first duty cycle to generate a first control signal, and the DC / DC boost circuit can be switched to the charging mode according to the first control signal.

[0088] It can be understood that the actual total voltage in this application refers to the total voltage output by the grid-type photovoltaic system, which can be obtained by real-time measurement of the output voltage of the grid-type photovoltaic system through a voltage sensor. During measurement, the voltage sensor can be installed at the end of the output cable of the grid-type photovoltaic system to calculate the actual total voltage by measuring the voltage difference at both ends of the cable; the first reference total voltage refers to the reference value set in advance by the user according to the performance and actual needs of the grid-type photovoltaic system; and the actual total current refers to the total current output by the grid-type photovoltaic system, which can be obtained by real-time measurement of the output current of the grid-type photovoltaic system through a current sensor. During measurement, the voltage sensor can be installed at the end of the output cable of the grid-type photovoltaic system to calculate the actual total current by measuring the current difference at both ends of the cable.

[0089] Among them, signal pulse width modulation refers to a technology used to control power systems. It can control parameters such as voltage and current of the power system by adjusting parameters such as pulse width and frequency. When generating the first control signal, the present application can adjust the PWM (Pulse Width Modulation) signal through the controller, and adjust the duty cycle of the PWM signal to the first duty cycle to achieve control of the output voltage and current to generate the first control signal.

[0090] In one embodiment, the DC / DC boost circuit in step S112 includes a first proportional-integral component and a second proportional-integral component; wherein the step of determining the first duty cycle of the DC / DC boost circuit based on the actual total voltage, the first reference total voltage, and the actual total current may include:

[0091] S1121: Calculate a first voltage difference between the actual total voltage and the first reference total voltage, and determine a reference total current corresponding to the first voltage difference through a first proportional integral link.

[0092] S1122: Calculate the current difference between the actual total current and the reference total current, and determine a first duty cycle corresponding to the current difference through a second proportional-integral link.

[0093] In one embodiment, the DC / DC boost circuit includes a first proportional-integral link and a second proportional-integral link. When determining the first duty cycle of the DC / DC boost circuit, a first voltage difference between the actual total voltage and the first reference total voltage can be calculated first, and a reference total current corresponding to the first voltage difference can be determined through the first proportional-integral link. Then, a current difference between the actual total current and the reference total current can be calculated, and a first duty cycle corresponding to the current difference can be determined through the second proportional-integral link.

[0094] Schematically, as shown in FIG3, FIG3 is a control schematic diagram of a DC / DC boost circuit provided in an embodiment of the present application; Mode 1 in FIG3 is a charging mode of the DC / DC boost circuit, wherein, when the DC / DC boost circuit needs to be switched to Mode 1, the actual total voltage u can be calculated first. dc and the first reference total voltage u dcref0 The first voltage difference is calculated by the first proportional integral link k p1 +k i1 / s to obtain the reference total current I of the photovoltaic string in the grid-type photovoltaic system dcref0 , then we can calculate I dcref0 The actual total current The current difference between the two is calculated and the current difference is converted into the current by the second proportional integral link k p2 +k i2 / s and then the first duty cycle D is obtained char .

[0095] In one embodiment, in step S120, the VSC inverter unit includes a lead-lag loop, an integral loop, an AC voltage loop, and a current loop. The step of starting the VSC inverter unit based on a preset grid-type control strategy may include:

[0096] S121: Acquire an actual total voltage and a second reference total voltage of the grid-type photovoltaic system, and calculate a second voltage difference between the actual total voltage and the second reference total voltage.

[0097] S122: Determine a phase angle corresponding to the second voltage difference through a lead-lag link and an integral link, and determine a first reference valve-side voltage and a second reference valve-side voltage of the VSC inverter unit through an AC voltage loop and a current loop.

[0098] S123: Generate a switching signal according to the phase angle, the first reference valve-side voltage, and the second reference valve-side voltage, and control the startup of the VSC inverter unit based on the switching signal.

[0099] In this embodiment, the VSC inverter unit includes a lead-lag link, an integral link, an AC voltage loop and a current loop, as shown in Figure 2. The DC voltage loop in Figure 2 includes a lead-lag link and an integral link. When starting the VSC inverter unit, the actual total voltage and the second reference total voltage of the grid-type photovoltaic system can be obtained first, and the second voltage difference between the actual total voltage and the second reference total voltage can be calculated. Then, the phase angle corresponding to the second voltage difference can be determined through the DC voltage loop, and the first reference valve-side voltage and the second reference valve-side voltage of the VSC inverter unit can be determined through the AC voltage loop and the current loop. Finally, a switching signal can be generated according to the phase angle, the first reference valve-side voltage and the second reference valve-side voltage, and the start-up of the VSC inverter unit can be controlled based on the switching signal.

[0100] Schematically, as shown in FIG4, FIG4 is a control schematic diagram of a DC voltage loop provided in an embodiment of the present application; In FIG4, the DC voltage loop is used to determine the phase angle θ ref When the actual total voltage u is calculated, dc and the second reference total voltage u dcref The second voltage difference is calculated by the lead-lag link (s+k1) / (k 2s +k3) is added to the rated angular frequency ω0 of the AC system, and the phase angle θ is obtained after the integral link 1 / s. ref .

[0101] Furthermore, as shown in FIG2 , the construction of the AC voltage loop and current loop in FIG2 is similar to that of a general double closed-loop vector control, and will not be described in detail here. The first reference valve-side voltage v of the VSC inverter unit is generated through these two links. cd and the second reference valve side voltage v cq After that, the phase angle θ can be ref It is used as the reference angle for abc / dq coordinate transformation and dq / abc coordinate inverse transformation, and for the first reference valve side voltage v cd and the second reference valve side voltage v cq After coordinate inverse transformation and PWM modulation, a switching signal is generated to control the start-up of the VSC inverter unit.

[0102] In one embodiment, switching the DC / DC boost circuit to the maximum power point tracking mode based on the duty cycle control strategy in step S120 may include:

[0103] S124: Obtain the reference output voltage, actual output current, and actual output power of a single photovoltaic string in the grid-connected photovoltaic system.

[0104] S125: Determine a second duty cycle of the DC / DC boost circuit according to the reference output voltage, the actual output current, and the actual output power.

[0105] S126: Performing pulse width modulation on the signal based on the second duty cycle to generate a second control signal, and switching the DC / DC boost circuit to a maximum power point tracking mode according to the second control signal.

[0106] In this embodiment, when the DC / DC boost circuit needs to be switched to the maximum power tracking mode, the reference output voltage, actual output current and actual output power of a single photovoltaic string in the grid-type photovoltaic system can be obtained first, and the second duty cycle of the DC / DC boost circuit can be determined based on the reference output voltage, actual output current and actual output power. Then, the signal pulse width modulation can be performed based on the second duty cycle to generate a second control signal, and the DC / DC boost circuit can be switched to the maximum power tracking mode according to the second control signal.

[0107] It can be understood that the reference output voltage in this application refers to the theoretical output voltage of a single photovoltaic string in a grid-type photovoltaic system, which can be obtained through the data sheet or nominal parameters of the grid-type photovoltaic system. Under normal circumstances, the reference output voltage is calculated based on factors such as the light intensity, temperature and installation angle of the photovoltaic system; the actual output current refers to the actual output current of a single photovoltaic string, which can be obtained by real-time measurement of the output current of the photovoltaic string by a current sensor. During measurement, the current measuring sensor can be installed at the end of the photovoltaic string output cable, and the actual output current can be calculated by measuring the current difference between the two ends of the cable; and the actual output power refers to the actual output power of a single photovoltaic string, which can be calculated by multiplying the actual output current and the reference output voltage.

[0108] In one embodiment, the DC / DC boost circuit in step S125 further includes a third proportional-integral link; wherein determining the second duty cycle of the DC / DC boost circuit according to the reference output voltage, the actual output current, and the actual output power may include:

[0109] S1251: Determine the reference output power of the PV string based on the reference output voltage and the actual output current.

[0110] S1252: Calculate a first power difference between the actual output power and the reference output power, and determine a second duty cycle corresponding to the first power difference through a third proportional-integral link.

[0111] In this embodiment, the DC / DC boost circuit also includes a third proportional-integral link. When determining the second duty cycle of the DC / DC boost circuit, the reference output power of the photovoltaic string can be first determined based on the reference output voltage and the actual output current, and then the first power difference between the actual output power and the reference output power can be calculated, and the second duty cycle corresponding to the first power difference can be determined through the third proportional-integral link.

[0112] Schematically, as shown in FIG3 , the mode 2 in FIG3 is the maximum power tracking mode of the DC / DC boost circuit. When the DC / DC boost circuit needs to be switched to mode 2, the reference output voltage u pvrefi and the actual output current I pvi After multiplication, the reference output power P of the photovoltaic string is obtained. pvrefi , then the reference output power P can be calculated pvrefi The actual output power P pvi The first power difference is calculated and the first power difference is converted into the first power difference through the third proportional integral link k p3 +k i3 / s and then the second duty cycle D is obtained mppti (i=1, 2, ..., n).

[0113] In one embodiment, the DC / DC boost circuit in step S150 further includes a differential filtering section, a power distribution section, a limiting section, and a fourth proportional-integral section; wherein switching the DC / DC boost circuit to the reserved active power mode based on the duty cycle control strategy may include:

[0114] S151: Acquire the actual total voltage of the grid-connected photovoltaic system and the reference output power of a single photovoltaic string in the grid-connected photovoltaic system.

[0115] S152: Determine the reference inertia support power corresponding to the actual total voltage through the differential filtering link and the power distribution link, and determine the reference adjustment power corresponding to the reference output power through the limiting link.

[0116] S153: Calculate a second power difference between the reference inertia support power and the reference adjustment power, and determine a third duty cycle corresponding to the second power difference through a fourth proportional integral link.

[0117] S154: Performing pulse width modulation on the signal based on the third duty cycle to generate a third control signal, and switching the DC / DC boost circuit to a reserved active power mode according to the third control signal.

[0118] In this embodiment, the DC / DC boost circuit also includes a fourth proportional-integral link. When determining the third duty cycle of the DC / DC boost circuit, the actual total voltage of the grid-type photovoltaic system and the reference output power of a single photovoltaic string in the grid-type photovoltaic system can be obtained first, and the reference inertia support power corresponding to the actual total voltage can be determined through the differential filtering link and the power distribution link, and the reference adjustment power corresponding to the reference output power can be determined through the limiting link. Then, the second power difference between the reference inertia support power and the reference adjustment power can be calculated, and the third duty cycle corresponding to the second power difference can be determined through the fourth proportional-integral link. Finally, the signal pulse width modulation can be performed based on the third duty cycle to generate a third control signal, and the DC / DC boost circuit can be switched to the reserved active mode according to the third control signal.

[0119] It should be noted that the reference output power here refers to the reference output power saved by the memory module when the DC / DC boost circuit is switched to the maximum power tracking mode. Therefore, when switching the DC / DC boost circuit to the reserved active power mode, it is necessary to first enter the maximum power tracking mode so that the reference output power can be saved through the memory module, and then it can be switched to the reserved active power mode.

[0120] Schematically, as shown in FIG3 , mode 3 in FIG3 is a reserved active mode of the DC / DC boost circuit. When the DC / DC boost circuit needs to be switched to mode 3, the actual total voltage u dc Through the differential filter k HS / (Ts+1) and power distribution link Then the reference inertia support power ΔP of a single photovoltaic string is obtained i , then the reference output power P pvrefi With reserved power system K p After multiplication, calculate the reference inertia support power ΔP i The second power difference is calculated and the second power difference is converted into the second power difference through the fourth proportional integral link k p4 +k i4 / s and then the third duty cycle D is obtained Hi (i=1,2,...,n).

[0121] The inertia support control device provided in an embodiment of the present application is described below. The inertia support control device described below and the inertia support control method described above can be referenced to each other.

[0122] In one embodiment, as shown in FIG5 , FIG5 is a flow chart of an inertia support control device for a grid-type photovoltaic system provided by an embodiment of the present application. The present application also provides an inertia support control device, including a first control module 210, a second control module 220, a demand acquisition module 230, a mode holding module 240, and a third control module 250, specifically including the following:

[0123] The first control module 210 is configured to lock the VSC inverter unit and switch the DC / DC boost circuit to a charging mode based on a preset duty cycle control strategy when the grid-connected photovoltaic system needs to be started.

[0124] The second control module 220 is used to monitor the DC bus voltage in real time, and after the DC bus voltage reaches a preset target voltage for a time longer than the preset target time, start the VSC inverter unit based on a preset grid-type control strategy, and switch the DC / DC boost circuit to a maximum power tracking mode based on a duty cycle control strategy.

[0125] The demand acquisition module 230 is used to obtain the scheduling demand of the grid-connected photovoltaic system.

[0126] The mode maintaining module 240 is configured to maintain the maximum power tracking mode of the DC / DC boost circuit when the scheduling requirement prioritizes power generation.

[0127] The third control module 250 is configured to switch the DC / DC boost circuit to a reserved active power mode based on a duty cycle control strategy when the scheduling requirement is inertia support priority.

[0128] In the above embodiment, the grid-type photovoltaic system includes a VSC inverter unit and a DC / DC boost circuit. When the grid-type photovoltaic system needs to be started, the VSC inverter unit can be locked, and the DC / DC boost circuit can be switched to a charging mode based on a preset duty cycle control strategy. This allows the configured energy storage of the grid-type photovoltaic system to be smoothly charged when the grid-type photovoltaic system is started, thereby providing stable power support for the grid-type photovoltaic system when necessary. During the configured energy storage charging process, the DC bus voltage can be monitored in real time. When the DC bus voltage remains at a preset target voltage for a period longer than a preset target time, the VSC inverter unit is started based on a preset grid-type control strategy, and the DC / DC boost circuit is switched to a maximum power tracking mode based on a duty cycle control strategy. This achieves maximum power output of the photovoltaic string and improves the power generation efficiency and energy utilization of the grid-type photovoltaic system. Subsequently, a scheduling demand of the photovoltaic system can be obtained, and the grid-type photovoltaic system can be switched to a corresponding mode based on the scheduling demand. For example, when the scheduling demand is to prioritize power generation, the maximum power tracking mode of the DC / DC boost circuit can be maintained, so that the inertia support energy of the grid-type photovoltaic system is entirely derived from the energy stored in the configured energy storage; when the scheduling demand is to prioritize inertia support, the DC / DC boost circuit can be switched to a reserved active power mode based on a duty cycle control strategy, with the energy stored in the configured energy storage as the main mode and the active power reserved by the photovoltaic panels as the auxiliary mode, to provide inertia support for the grid-type photovoltaic system. This application utilizes the grid-type control strategy of the VSC inverter unit and the three control modes of the DC / DC boost circuit to coordinate control of the grid-type photovoltaic system, which can achieve flexible inertia support on the basis of improving the stability of the system under weak grid conditions, thereby improving the stability and reliability of the power system.

[0129] In one embodiment, the first control module 210 may include:

[0130] The first data acquisition submodule is used to obtain the actual total voltage, the first reference total voltage and the actual total current of the grid-connected photovoltaic system.

[0131] The first duty cycle determination submodule is configured to determine a first duty cycle of the DC / DC boost circuit according to the actual total voltage, the first reference total voltage, and the actual total current.

[0132] The first mode switching submodule is configured to perform signal pulse width modulation based on a first duty cycle to generate a first control signal, and switch the DC / DC boost circuit to a charging mode according to the first control signal.

[0133] In one embodiment, the first duty cycle determination submodule may include:

[0134] The first data calculation unit is used to calculate a first voltage difference between the actual total voltage and the first reference total voltage, and determine a reference total current corresponding to the first voltage difference through a first proportional integral link.

[0135] The first duty cycle determining unit is used to calculate the current difference between the actual total current and the reference total current, and determine a first duty cycle corresponding to the current difference through a second proportional integral link.

[0136] In one embodiment, the second control module 220 may include:

[0137] The inverter data acquisition submodule is used to obtain the actual total voltage and the second reference total voltage of the grid-type photovoltaic system, and calculate the second voltage difference between the actual total voltage and the second reference total voltage.

[0138] The inverter data calculation submodule is used to determine the phase angle corresponding to the second voltage difference through the lead-lag link and the integral link, and to determine the first reference valve-side voltage and the second reference valve-side voltage of the VSC inverter unit through the AC voltage loop and the current loop.

[0139] The inverter unit starter module is used to generate a switching signal according to the phase angle, the first reference valve-side voltage and the second reference valve-side voltage, and control the start-up of the VSC inverter unit based on the switching signal.

[0140] In one embodiment, the second control module 220 may further include:

[0141] The second data acquisition submodule is used to obtain the reference output voltage, actual output current and actual output power of a single photovoltaic string in the grid-type photovoltaic system.

[0142] The second duty cycle determination submodule is used to determine the second duty cycle of the DC / DC boost circuit according to the reference output voltage, the actual output current and the actual output power.

[0143] The second mode switching submodule is used to perform signal pulse width modulation based on the second duty cycle to generate a second control signal, and switch the DC / DC boost circuit to the maximum power tracking mode according to the second control signal.

[0144] In one embodiment, the second duty cycle determination submodule may include:

[0145] The second data calculation unit is used to determine the reference output power of the photovoltaic string according to the reference output voltage and the actual output current.

[0146] The second duty cycle determining unit is used to calculate a first power difference between the actual output power and the reference output power, and determine a second duty cycle corresponding to the first power difference through a third proportional integral link.

[0147] In one embodiment, the third control module 250 may include:

[0148] The third data acquisition submodule is used to obtain the actual total voltage of the grid-type photovoltaic system and the reference output power of a single photovoltaic string in the grid-type photovoltaic system.

[0149] The power data calculation submodule is used to determine the reference inertia support power corresponding to the actual total voltage through the differential filtering link and the power distribution link, and to determine the reference adjustment power corresponding to the reference output power through the limiting link.

[0150] The third duty cycle determination submodule is used to calculate the second power difference between the reference inertia support power and the reference adjustment power, and determine the third duty cycle corresponding to the second power difference through a fourth proportional integral link.

[0151] The third mode switching submodule is configured to perform signal pulse width modulation based on a third duty cycle to generate a third control signal, and switch the DC / DC boost circuit to a maximum power tracking mode according to the third control signal.

[0152] In one embodiment, the present application also provides a storage medium storing computer-readable instructions. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the inertia support control method as described in any of the above embodiments.

[0153] In one embodiment, the present application also provides a computer device having computer-readable instructions stored therein. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the inertia support control method as described in any one of the above embodiments.

[0154] Schematically, as shown in FIG6 , FIG6 is a schematic diagram of the internal structure of a computer device provided in an embodiment of the present application, and the computer device 300 can be provided as a server. Referring to FIG6 , the computer device 300 includes a processing component 302, which further includes one or more processors, and a memory resource represented by a memory 301 for storing instructions that can be executed by the processing component 302, such as an application. The application stored in the memory 301 may include one or more modules, each of which corresponds to a set of instructions. In addition, the processing component 302 is configured to execute instructions to perform the inertia support control method of any of the above embodiments.

[0155] The computer device 300 may further include a power supply component 303 configured to perform power management of the computer device 300, a wired or wireless network interface 304 configured to connect the computer device 300 to a network, and an input / output (I / O) interface 305. The computer device 300 may operate based on an operating system stored in the memory 301, such as Windows Server™, Mac OS X™, Unix™, Linux™, Free BSD™, or the like.

[0156] Those skilled in the art will understand that the structure shown in FIG6 is merely a block diagram of a portion of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different arrangement of components.

[0157] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0158] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referenced to each other.

[0159] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for controlling inertial support of a grid-type photovoltaic system, characterized in that: The grid-type photovoltaic system includes a VSC inverter unit and a DC / DC boost circuit, and the method includes: When the grid-forming photovoltaic system needs to be started, the VSC inverter unit is locked, and the DC / DC boost circuit is switched to a charging mode based on a preset duty cycle control strategy; Monitor the DC bus voltage in real time, and when the time duration for the DC bus voltage to reach a preset target voltage is longer than the preset target time duration, start the VSC inverter unit based on a preset grid-type control strategy, and switch the DC / DC boost circuit to a maximum power tracking mode based on the duty cycle control strategy; Obtaining a dispatching demand of the grid-connected photovoltaic system, wherein the dispatching demand includes power generation priority and inertia support priority; When the scheduling demand is power generation priority, maintaining the maximum power tracking mode of the DC / DC boost circuit; When the scheduling requirement is inertia support priority, the DC / DC boost circuit is switched to a reserved active power mode based on the duty cycle control strategy.

2. The inertia support control method according to claim 1, characterized in that: The step of switching the DC / DC boost circuit to a charging mode based on a preset duty cycle control strategy includes: Obtaining an actual total voltage, a first reference total voltage, and an actual total current of the grid-connected photovoltaic system; Determining a first duty cycle of the DC / DC boost circuit according to the actual total voltage, the first reference total voltage and the actual total current; A signal pulse width modulation is performed based on the first duty cycle to generate a first control signal, and the DC / DC boost circuit is switched to a charging mode according to the first control signal.

3. The inertia support control method according to claim 2, characterized in that: The DC / DC boost circuit includes a first proportional-integral link and a second proportional-integral link; The step of determining a first duty cycle of the DC / DC boost circuit according to the actual total voltage, the first reference total voltage and the actual total current comprises: Calculating a first voltage difference between the actual total voltage and the first reference total voltage, and determining a reference total current corresponding to the first voltage difference through the first proportional integral link; A current difference between the actual total current and the reference total current is calculated, and a first duty cycle corresponding to the current difference is determined through the second proportional-integral link.

4. The inertia support control method according to claim 1, characterized in that: The VSC inverter unit includes a lead-lag link, an integral link, an AC voltage loop and a current loop; The starting of the VSC inverter unit based on a preset grid-type control strategy includes: Acquiring an actual total voltage and a second reference total voltage of the photovoltaic system, and calculating a second voltage difference between the actual total voltage and the second reference total voltage; Determine the phase angle corresponding to the second voltage difference through the lead-lag link and the integral link, and determine the first reference valve-side voltage and the second reference valve-side voltage of the VSC inverter unit through the AC voltage loop and the current loop; A switching signal is generated according to the phase angle, the first reference valve-side voltage, and the second reference valve-side voltage, and activation of the VSC inverter unit is controlled based on the switching signal.

5. The inertia support control method according to claim 1, characterized in that: The step of switching the DC / DC boost circuit to a maximum power tracking mode based on the duty cycle control strategy includes: Obtaining a reference output voltage, an actual output current, and an actual output power of a single photovoltaic string in the grid-connected photovoltaic system; Determine a second duty cycle of the DC / DC boost circuit according to the reference output voltage, the actual output current and the actual output power; A signal pulse width modulation is performed based on the second duty cycle to generate a second control signal, and the DC / DC boost circuit is switched to a maximum power tracking mode according to the second control signal.

6. The inertia support control method according to claim 5, characterized in that: The DC / DC boost circuit also includes a third proportional-integral link; The step of determining the second duty cycle of the DC / DC boost circuit according to the reference output voltage, the actual output current and the actual output power comprises: Determine the reference output power of the photovoltaic string according to the reference output voltage and the actual output current; A first power difference between the actual output power and the reference output power is calculated, and a second duty cycle corresponding to the first power difference is determined through the third proportional-integral link.

7. The inertia support control method according to claim 1, characterized in that: The DC / DC boost circuit also includes a differential filter link, a power distribution link, a limit link and a fourth proportional integral link; The step of switching the DC / DC boost circuit to a reserved active power mode based on the duty cycle control strategy includes: Acquiring an actual total voltage of the grid-type photovoltaic system and a reference output power of a single photovoltaic string in the grid-type photovoltaic system; Determine the reference inertia support power corresponding to the actual total voltage through the differential filtering link and the power distribution link, and determine the reference adjustment power corresponding to the reference output power through the limiting link; Calculating a second power difference between the reference inertia support power and the reference adjustment power, and determining a third duty cycle corresponding to the second power difference through the fourth proportional integral link; A signal pulse width modulation is performed based on the third duty cycle to generate a third control signal, and the DC / DC boost circuit is switched to a maximum power tracking mode according to the third control signal.

8. An inertia support control device, characterized in that: include: A first control module is used to lock the VSC inverter unit when the grid-forming photovoltaic system needs to be started, and switch the DC / DC boost circuit to a charging mode based on a preset duty cycle control strategy; A second control module is used to monitor the DC bus voltage in real time, and after the DC bus voltage reaches a preset target voltage for a time period greater than a preset target time period, start the VSC inverter unit based on a preset grid-type control strategy, and switch the DC / DC boost circuit to a maximum power tracking mode based on the duty cycle control strategy; A demand acquisition module, used to acquire the scheduling demand of the grid-building photovoltaic system, wherein the scheduling demand includes power generation priority and inertia support priority; A mode maintaining module, used for maintaining a maximum power tracking mode of the DC / DC boost circuit when the scheduling demand is power generation priority; The third control module is used to switch the DC / DC boost circuit to a reserved active power mode based on the duty cycle control strategy when the scheduling requirement is inertia support priority.

9. A storage medium, characterized in that: The storage medium stores computer-readable instructions, and when the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the inertial support control method as claimed in any one of claims 1 to 7.

10. A computer device, characterized in that: include: one or more processors, and memory; The memory stores computer-readable instructions, and when the computer-readable instructions are executed by the one or more processors, the steps of the inertial support control method according to any one of claims 1 to 7 are performed.

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