Network configuration control method and device for voltage source type power electronic equipment

Abstract

The embodiment of the present application relates to the technical field of power electronic control, and provides a network construction control method and device of a voltage source type power electronic equipment, the method comprises the following steps: when a target power grid appears a fault, judging a fault level; determining a starting judgment strategy of a virtual impedance based on the fault level; starting the virtual impedance based on the starting judgment strategy, and adopting the virtual impedance to carry out network construction control current limiting in a three-phase stationary coordinate system, wherein the three-phase stationary coordinate system is the basis for network construction control to limit the equipment current in the target power grid within an overcurrent capacity; in the network construction control current limiting state, controlling the voltage source type power electronic equipment to carry out network construction control on the target power grid. Therefore, the overcurrent problem caused by AC fault can be well coped with, and the actual equipment operation reliability is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronic control, in particular to a grid-forming control method and device for voltage source type power electronic equipment. BACKGROUND

[0002] With the increasing proportion of new energy in the AC system, the control characteristics of power electronic equipment bring challenges to the stable operation control of the traditional power system. With the in-depth study of the stability of high-proportion new energy AC systems, higher demands are also put forward for the control characteristics of power electronic equipment. Grid-forming control is a new emerging power system control technology. In order to better adapt to the stability requirements of traditional power systems, this control technology is gradually applied to power electronic equipment such as new energy generation (such as wind energy, photovoltaic), energy storage and new energy transmission systems. Grid-forming control technology mainly simulates the characteristics of traditional synchronous generators and provides voltage and frequency support. Grid-forming control needs to consider the challenges of safe and stable operation under the condition of limited overcurrent capacity of actual equipment.

[0003] Under the condition of power system fault, due to the limitation of equipment overcurrent capacity, grid-forming control needs to dynamically adjust the output current to limit the current within a safe range and avoid equipment damage. The literature "Modeling and Improved Control of Virtual Synchronous Generator under Symmetrical Fault of Power Grid" adopts virtual resistance technology and phasor current limiting technology, which can limit the fault current of virtual synchronous generator under power grid fault and ensure its safe operation without being off the grid during power grid fault. The literature considers the current limiting under symmetrical fault of power grid, and the phasor current limiting technology is realized in the rotating coordinate system, which needs time to extract the sequence components. In terms of control, it is slower than in the stationary coordinate system. SUMMARY

[0004] The present application provides a grid-forming control method and device for voltage source type power electronic equipment, which solves the defect that the grid-forming control current limiting function is imperfect due to the limitation of equipment overcurrent capacity under different fault conditions of the power system in the prior art, realizes that the grid-forming control well deals with the overcurrent problem caused by AC fault, and improves the actual equipment operation reliability.

[0005] The present application provides a grid-forming control method for voltage source type power electronic equipment, comprising:

[0006] When a target power grid fails, determine the fault level;

[0007] Determine the start judgment strategy of virtual impedance based on the fault level;

[0008] start the virtual impedance based on the starting judgment strategy, and perform network construction control current limiting using the virtual impedance in a three-phase stationary coordinate system, wherein the three-phase stationary coordinate system is the basis for the network construction control to limit the currents of the devices in the target power grid within overcurrent capability;

[0009] In the network construction control current limiting state, the voltage source type power electronic device controls the network construction of the target power grid, and generates a three-phase virtual voltage based on the virtual impedance to achieve the purpose of current limiting.

[0010] In one possible implementation, the method further comprises:

[0011] detecting a current instantaneous value of a three-phase alternating current and a voltage positive sequence component modulus value of a three-phase alternating voltage of the target power grid;

[0012] if the current instantaneous value is greater than or equal to a preset device overcurrent constant value or the voltage positive sequence component modulus value is less than a primary fault positive sequence voltage constant value, determining that the fault level is a primary fault;

[0013] detecting a three-phase alternating voltage effective value of the target power grid;

[0014] if the voltage positive sequence component modulus value or the voltage effective value is between a lower limit value of normal operation of the target power grid and a preset positive sequence voltage or voltage effective value, determining that the fault level is a secondary fault.

[0015] In one possible implementation, the method further comprises:

[0016] if it is determined that the fault level is a primary fault, immediately starting the virtual impedance, and the starting judgment strategy is to start the virtual impedance by using the current instantaneous value or voltage criterion;

[0017] if it is determined that the fault level is a secondary fault, the starting judgment strategy is to start the virtual impedance by using the voltage criterion.

[0018] In one possible implementation, the method further comprises:

[0019] after starting the virtual impedance, superimposing a virtual voltage drop on a potential voltage in a three-phase stationary coordinate system of the target power grid, and limiting the current passing through the devices in the target power grid by a virtual voltage drop corresponding to the virtual impedance.

[0020] In one possible implementation, the method further comprises:

[0021] calculating a voltage drop generated by the virtual impedance;

[0022] determining a corresponding virtual voltage drop based on the voltage drop generated by the virtual impedance, and generating a target modulation wave based on the virtual voltage drop;

[0023] controlling the switching action of the voltage source type power electronic device based on the target modulation wave, and controlling the output current and voltage;

[0024] the voltage output by the voltage source type power electronic device limits the current passing through the device in the target power grid.

[0025] In one possible implementation, the method further comprises:

[0026] monitoring the changes in current and voltage while controlling the voltage source type power electronic device to perform the grid-forming control process for the target power grid;

[0027] dynamically adjusting the virtual impedance based on the changes in current and voltage.

[0028] In one possible implementation, the method further comprises:

[0029] determining the value of the virtual impedance based on the overcurrent capability of the voltage source type power electronic device.

[0030] The application also provides a grid-forming control device for a voltage source type power electronic device, comprising the following modules:

[0031] a judging module configured to judge the fault level when a fault occurs in a target power grid;

[0032] a determining module configured to determine a start judgment strategy for a virtual impedance based on the fault level;

[0033] a control module configured to start the virtual impedance based on the start judgment strategy, and perform grid-forming control current limiting using the virtual impedance in a three-phase stationary coordinate system, wherein the three-phase stationary coordinate system is the basis for the grid-forming control to quickly limit the current of the device in the target power grid within the overcurrent capability;

[0034] the control module is further configured to control the voltage source type power electronic device to perform grid-forming control for the target power grid in the grid-forming control current limiting state, and generate a three-phase virtual voltage according to the virtual impedance to achieve the purpose of current limiting.

[0035] The application also provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the grid-forming control method for a voltage source type power electronic device according to any one of the above.

[0036] The application also provides a non-transitory computer readable storage medium having a computer program stored thereon, wherein the computer program is executable on a processor to implement the grid-forming control method for a voltage source type power electronic device according to any one of the above.

[0037] The application further provides a computer program product comprising a computer program which, when executed by a processor, implements the grid-forming control method of the voltage source power electronic device.

[0038] The grid-forming control method and device of the voltage source power electronic device provided by the application, by judging the fault level when the target grid fails, determining the input strategy of the virtual impedance based on the fault level, starting the virtual impedance based on the input strategy, and using the virtual impedance to perform grid-forming control current limiting in the three-phase stationary coordinate system, wherein the three-phase stationary coordinate system is the basis for the grid-forming control to limit the device current in the target grid within the overcurrent capability; in the grid-forming control current limiting state, the voltage source power electronic device controls the grid-forming control of the target grid, and generates a three-phase virtual voltage according to the virtual impedance to achieve the purpose of current limiting. Compared with the defects in the prior art that the grid-forming control current limiting function is imperfect due to the limitation of the device overcurrent capability under different fault conditions of the power system, the application realizes the current limiting of the virtual impedance in the three-phase stationary coordinate system, and the current limiting measure realized in the coordinate system does not require a filtering link for the device with limited overcurrent capability, the virtual impedance is started by using the current instantaneous value or voltage criterion in the case of primary fault, so that the current limiting function can be realized more quickly; at the same time, the stable operation in the case of secondary fault is also considered, the virtual impedance criterion is started by using the positive sequence component modulus or effective value of the voltage, the repeated input and output of the virtual impedance is avoided, the current is limited within the device overcurrent capability, the overcurrent problem caused by the AC fault can be well coped with, and the actual device operation reliability is improved. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0040] Figure 1 is one of the flowcharts of the grid-forming control method of the voltage source power electronic device provided by the application.

[0041] Figure 2 is the second flowchart of the grid-forming control method of the voltage source power electronic device provided by the application.

[0042] Figure 3 is the structural diagram of the grid-forming control method of the voltage source power electronic device provided by the application.

[0043] Figure 4It is the structural schematic view of the network configuration control device of the voltage source type power electronic equipment provided by the application.

[0044] Figure 5 It is the structural schematic view of the electronic equipment provided by the application. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0046] In order to facilitate the understanding of the embodiments of the present application, the following will be further explained and described in specific embodiments in combination with the drawings, and the embodiments do not constitute a limitation on the embodiments of the present application.

[0047] Figure 1 It is one of the flow schematic views of the network configuration control method of the voltage source type power electronic equipment provided by the application, as shown in the figure, the method comprises the following: Figure 1

[0048] S11, when a target power grid fails, judging the fault level.

[0049] The current limiting method based on virtual impedance in the embodiments of the present application is realized in a three-phase stationary coordinate system. For the equipment with limited overcurrent capacity, the current limiting measure realized in the coordinate system does not need a filter link, and this measure is the basis for quickly realizing current limiting. The virtual impedance is started by using the current instantaneous value or voltage criterion in serious fault, so that the current limiting function can be realized more quickly. At the same time, the stable operation in slight fault is also considered, and the virtual impedance criterion is started by adding the voltage positive sequence component modulus or effective value criterion, so as to avoid the repeated start and stop of the virtual impedance. Since the three-phase stationary coordinate system is used, the virtual impedance can limit the current within the overcurrent capacity of the equipment for symmetric fault and asymmetric fault conditions.

[0050] Specifically, when the target power grid fails, the current instantaneous value of the three-phase alternating current of the target power grid and the voltage positive sequence component modulus of the three-phase alternating voltage are detected. If the current instantaneous value is greater than or equal to the preset device overcurrent setting value or the voltage positive sequence component modulus is less than the primary fault positive sequence voltage setting value, it is determined that the fault level is primary fault (serious fault). The three-phase alternating voltage effective value of the target power grid is detected, and if the voltage positive sequence component modulus or the voltage effective value is between the lower limit value of the normal operation of the target power grid and the preset positive sequence voltage or voltage effective value setting value, it is determined that the fault level is secondary fault (slight fault).

[0051] ​S12, determine a start judgment strategy of the virtual impedance based on the fault level.

[0052] S13, start the virtual impedance based on the start judgment strategy, and perform network construction control current limiting in a three-phase stationary coordinate system using the virtual impedance.

[0053] The voltage source type power electronic device can be a low-voltage two-level full-controlled power electronic device or a high-voltage multi-level cascade power electronic device. The currentless inner loop network construction control current limiting method proposed in the present application can be used in the above devices, and can well cope with the overcurrent problem caused by AC fault, improve the actual device operation reliability, and has high economic efficiency.

[0054] In the three-phase stationary coordinate system, the voltage drop caused by the superposition of the virtual impedance on the modulation wave is used to realize the fast current limiting function in the AC fault condition. The three-phase stationary coordinate system is the basis for the network construction control to quickly limit the device current in the target power grid within the overcurrent capacity.

[0055] If it is determined that the fault level is a first-level fault, the corresponding virtual impedance is used, that is, when the current is over-limited or the voltage amplitude is less than the threshold value, the corresponding virtual impedance is put into operation to quickly limit the current.

[0056] The value of the virtual impedance is determined by the actual hardware overcurrent capacity, and the virtual impedance can still limit the current within the hardware overcurrent capacity under different voltage drop conditions.

[0057] If it is determined that the fault level is a second-level fault, the start judgment strategy is to start the virtual impedance through the voltage criterion to avoid the repeated start and stop of the virtual impedance. In this case, although the current may not have reached the overcurrent limit value, the voltage drop has shown that there may be potential problems in the system, and measures need to be taken to maintain stable operation.

[0058] S14, in the network construction control current limiting state, control the voltage source type power electronic device to perform network construction control on the target power grid.

[0059] Through the above network construction control current limiting measures, the voltage source type power electronic device can quickly and effectively limit the current when the power grid fails, and at the same time provide necessary voltage and frequency support for the power grid, to ensure the stable operation of the target power grid.

[0060] The application provides a network construction control method and device for a voltage source type power electronic equipment.Compared with the prior art, the method can realize current limiting of the virtual impedance in a three-phase stationary coordinate system, and the current limiting measure realized in the three-phase stationary coordinate system does not need a filter link, the virtual impedance is started by using a current instantaneous value or a voltage criterion in a serious fault, so that the current limiting function can be realized more quickly, and the stable operation in a slight fault is also considered, the virtual impedance is started by using a voltage positive sequence component modulus or an effective value criterion, the repeated starting and stopping of the virtual impedance is avoided, the current is limited in the overcurrent capacity of the equipment, the overcurrent problem caused by the AC fault can be well solved, and the actual equipment operation reliability is improved.

[0061] Figure 2 is a flowchart of a network construction control method for a voltage source type power electronic equipment provided by the application, as shown in the figure, the method comprises the following steps. Figure 2

[0062] The current limiting method based on the virtual impedance in the embodiment of the application is realized in a three-phase stationary coordinate system, the current limiting measure realized in the three-phase stationary coordinate system does not need a filter link, the virtual impedance is started by using a current instantaneous value or a voltage criterion in a serious fault, so that the current limiting function can be realized more quickly, and the stable operation in a slight fault is also considered, the virtual impedance is started by using a voltage positive sequence component modulus or an effective value criterion, the repeated starting and stopping of the virtual impedance is avoided, and the current is limited in the overcurrent capacity of the equipment.

[0063] S21, detect a current instantaneous value of a three-phase AC current and a voltage positive sequence component modulus of a three-phase AC voltage of the target network.

[0064] Specifically, when the target power grid fails, the current instantaneous value of the three-phase alternating current and the positive sequence component modulus value of the three-phase alternating voltage in the target power grid are monitored in real time. The current instantaneous value refers to the actual value of the current at a certain time. Since the alternating current is a sine wave that changes with time, the current instantaneous value can accurately reflect the state of the current at each time, providing basic data for subsequent fault judgment; the positive sequence component modulus value of the voltage is an important parameter considering factors such as the phase sequence of the voltage, which can reflect the symmetry and quality of the grid voltage.

[0065] S22, if the current instantaneous value is greater than or equal to the preset device overcurrent setting value or the positive sequence component modulus value of the voltage is less than the primary fault positive sequence voltage setting value, the fault level is determined to be a primary fault.

[0066] The detected current instantaneous value is compared with the preset device overcurrent setting value. The device overcurrent setting value is a threshold value determined according to factors such as the rated current of the power grid equipment and the maximum allowable overload current. If the current instantaneous value is greater than or equal to the device overcurrent setting value, it means that the current in the power grid has exceeded the range that the equipment can safely withstand, and the fault level is determined to be a primary fault. The primary fault is a more serious fault type, indicating that there may be a short circuit or other serious problem in the power grid, which requires immediate action.

[0067] S23, detecting the three-phase alternating voltage effective value of the target power grid.

[0068] The three-phase alternating voltage of the target power grid is detected. The positive sequence component modulus value of the voltage or the voltage effective value can be detected. The positive sequence component modulus value of the voltage is an important parameter considering factors such as the phase sequence of the voltage, which can reflect the symmetry and quality of the grid voltage; the voltage effective value is a commonly used index to measure the size of the alternating voltage, which represents the average level of the alternating voltage in a cycle.

[0069] S24, if the positive sequence component modulus value of the voltage or the voltage effective value is between the lower limit value of the normal operation of the target power grid and the preset positive sequence voltage or voltage effective value, the fault level is determined to be a secondary fault.

[0070] The detected positive sequence component modulus value of the voltage or the voltage effective value is compared with the lower limit value of the normal operation of the target power grid and the preset positive sequence voltage setting value or the voltage effective value. The preset positive sequence voltage setting value is a lower voltage threshold value. When the voltage is lower than this value, it means that the grid voltage has dropped seriously, which may be caused by a power grid failure. If the positive sequence component modulus value of the voltage is less than the preset positive sequence voltage setting value, the fault level is determined to be a secondary fault.

[0071] The target power grid normal operation lower limit value is the lowest voltage value allowed by the power grid in normal operation. When the voltage is within this interval, although the severity does not reach the level of a primary fault, there is still a certain abnormal situation, which needs to be handled as a secondary fault.

[0072] S25, if it is determined that the fault level is a primary fault, the virtual impedance is immediately started, and the starting judgment strategy is to start the virtual impedance through the current instantaneous value or voltage criterion.

[0073] If it is determined through the previous judgment that the fault level is a primary fault, immediate direct measures need to be taken to respond, so the virtual impedance is directly started. The virtual impedance is an impedance simulated by software algorithms and the like, which can limit the current in the power grid.

[0074] S26, if it is determined that the fault level is a secondary fault, the starting judgment strategy is to start the virtual impedance through the voltage criterion.

[0075] If it is determined that the fault level is a secondary fault, the virtual impedance needs to be started through the voltage criterion. The voltage criterion is to determine whether the condition for starting the virtual impedance is met according to the related parameters of the voltage (such as the voltage positive sequence component modulus or the voltage effective value, etc.). Because the secondary fault is relatively light compared to the primary fault, it is necessary to decide whether to start the virtual impedance according to the specific situation of the voltage, in order to achieve more accurate control.

[0076] S27, after starting the virtual impedance, the virtual impedance is superimposed on the potential voltage in the three-phase stationary coordinate system of the target power grid, and the current passing through the equipment in the target power grid is limited through the virtual pressure drop corresponding to the virtual impedance.

[0077] Combining Figure 3 the structure diagram of the grid control method of the voltage source type power electronic device shown, wherein, and are the actual value and the target value of the active power, respectively; is the frequency reference value; is the virtual rotational inertia; is the damping coefficient; , is the internal potential amplitude and phase angle generated by the power outer ring; , , is the internal potential generated by the power outer ring in the three-phase stationary coordinate system; , , is the actual alternating current instantaneous value; is the time constant; , is the virtual resistance and virtual inductance; , , is the voltage drop of the virtual impedance in the three-phase stationary coordinate system; , , is the final modulation wave in the three-phase stationary coordinate system. In the three-phase stationary coordinate system, the voltage drop caused by superimposing the virtual impedance on the modulation wave is used to achieve the fast current limiting function under AC fault conditions. The calculation method of the virtual impedance is as follows:

[0078] A graded virtual impedance is used, that is, when the current exceeds the limit or the voltage amplitude is less than the threshold (level one fault), or the modulus of the voltage positive sequence component or the voltage effective value is between the lower limit of the normal operation of the grid voltage and the positive sequence voltage set value of the level one fault (level two fault), the virtual impedance calculated by the following formula is put into use:

[0079]

[0080] in is the actual instantaneous value of current, is the overcurrent setting value (matched with the overcurrent capacity of the equipment), It is the set value of positive sequence voltage for severe faults. is the AC system angular frequency, is a virtual resistor, is the virtual reactance, is the virtual inductor, is the virtual resistance value that needs to be input, It is the lower limit of the normal operation of the grid voltage.

[0081] In order to ensure a better current limiting effect, the hardware overcurrent capability and voltage drop are considered, and the constraints are:

[0082]

[0083] It can be solved as:

[0084]

[0085]

[0086] in is the actual instantaneous value of current, is the overcurrent capacity of the device, is the ratio of the reactance to the resistance of the virtual impedance, is the actual voltage positive sequence component modulus or effective value, is the actual equivalent resistance of the device, is the actual reactance of the device, The rated voltage value of the busbar connected to the device, Calculate a threshold value for the virtual impedance voltage.

[0087] In summary, the specific value of the virtual impedance can be calculated, but how to realize the virtual reactance in the three-phase stationary coordinate system is a key problem to be considered.

[0088] The virtual reactance should be used to Simulation, because the integral element s has instability, very easy to be disturbed, consider increasing a first-order inertia element, constitute a lead adjustment link. Among them is the turning angle frequency of inertia element.

[0089]

[0090] In order to retain the attention of 50Hz frequency band, the turning angle frequency can be taken as 150Hz, that is . The solution is .

[0091] It should be noted that, because there is no current in the inner ring of the network control without direct limit the current measures, need to consider in the light fault (the actual AC voltage is greater than and less than the lower limit of the normal operation of AC voltage ), the actual AC current has not immediately reached the overcurrent setting, if the current limit at this time only through the input of virtual impedance, will cause the repeated investment of virtual impedance, not conducive to the steady state operation of light fault. So at this time, the AC voltage criterion is added, that is, in the light fault, the input of virtual impedance is started through the voltage criterion, to avoid the repeated investment of virtual impedance. In the serious fault (the actual AC voltage is less than ), the current instantaneous value criterion will quickly invest virtual impedance to limit the current, the voltage criterion due to the need to calculate the positive sequence component or effective value, the calculation time is longer than the current instantaneous value, not conducive to the fault occurs at the moment of limiting current.

[0092] The voltage drop generated by the virtual impedance is:

[0093]

[0094]

[0095]

[0096] The final modulation wave is:

[0097]

[0098]

[0099]

[0100] Among them,

[0101] is the amplitude and phase angle of the internal potential generated by the power outer loop;

[0102] is the actual alternating current instantaneous value;

[0103] is the voltage drop of the virtual impedance in the three-phase stationary coordinate system;

[0104] is the final modulation wave in the three-phase stationary coordinate system.

[0105] It should be noted that, since the application adopts the three-phase stationary coordinate system, the voltage drop generated by the virtual impedance is generated according to the actual three-phase current. When an asymmetric fault occurs, the corresponding negative sequence component modulation voltage will also be present in the final modulation wave, so the current limiting method provided in the application also has a certain limiting effect on the negative sequence component.

[0106] Compared with the prior art, the method of the embodiment of the application mainly superimposes the virtual voltage drop corresponding to the virtual impedance on the three-phase internal potential voltage as the final modulation wave, the value of the virtual impedance is determined by the actual hardware overcurrent capacity, the calculation of the virtual impedance adopts a lead adjustment link, and the virtual impedance on-off criterion adopts the combination of the alternating current instantaneous value and the positive sequence component modulus or effective value of the alternating voltage. The measure of adding the virtual impedance in the three-phase stationary coordinate system can realize the current limiting measure without a filter link in the coordinate system for the equipment with limited overcurrent capacity, and the virtual impedance is started by the current instantaneous value or voltage criterion in a serious fault, so that the current limiting function can be realized more quickly. At the same time, the stable operation in a slight fault is also considered, the virtual impedance criterion is started by adding the positive sequence component modulus or effective value criterion of the voltage, so as to avoid the repeated on-off of the virtual impedance. Since the application adopts the three-phase stationary coordinate system, the virtual impedance can limit the current within the overcurrent capacity of the equipment for symmetric fault and asymmetric fault conditions.

[0107] The network configuration control device of the voltage source type power electronic equipment provided by the application is described below, and the network configuration control device of the voltage source type power electronic equipment described below can be correspondingly referred to the network configuration control method of the voltage source type power electronic equipment described above.

[0108] Figure 4 ​​​​​​​​​​is a structural schematic diagram of a network construction control device of a voltage source type power electronic equipment provided by the application, and specifically comprises

[0109] A judgment module 401 is configured to judge a fault level when a target power grid is faulty. For details, refer to the related description of the method embodiment.

[0110] A determination module 402 is configured to determine a start judgment strategy of a virtual impedance based on the fault level. For details, refer to the related description of the method embodiment.

[0111] A control module 403 is configured to start the virtual impedance based on the start judgment strategy and perform network construction control current limiting in a three-phase stationary coordinate system by using the virtual impedance, wherein the three-phase stationary coordinate system is a basis for network construction control to limit the current of the equipment in the target power grid within an overcurrent capability. For details, refer to the related description of the method embodiment.

[0112] The control module 403 is further configured to control the voltage source type power electronic equipment to perform network construction control on the target power grid in a network construction control current limiting state. For details, refer to the related description of the method embodiment.

[0113] Figure 5 An example of an entity structure schematic diagram of an electronic device is shown in Figure 5 As shown in the figure, the electronic device can include a processor 810, a communications interface 820, a memory 830 and a communications bus 840, wherein the processor 810, the communications interface 820 and the memory 830 complete mutual communication through the communications bus 840. The processor 810 can invoke a logical instruction in the memory 830 to execute a network construction control method of a voltage source type power electronic equipment, which includes: judging a fault level when a target power grid is faulty; determining a start judgment strategy of a virtual impedance based on the fault level; starting the virtual impedance based on the start judgment strategy and performing network construction control current limiting in a three-phase stationary coordinate system by using the virtual impedance, wherein the three-phase stationary coordinate system is a basis for network construction control to limit the current of the equipment in the target power grid within an overcurrent capability; and controlling the voltage source type power electronic equipment to perform network construction control on the target power grid in a network construction control current limiting state.

[0114] Further, the logic instructions in the memory 830 described above can be implemented in the form of software functional units and sold or used as independent products, and can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the parts that make contributions to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0115] In another aspect, the present application also provides a computer program product, which comprises a computer program, the computer program can be stored on a non-transitory computer readable storage medium, and the computer program is executed by a processor, so that the computer can execute the grid forming control method of the voltage source type power electronic device provided by the above-mentioned methods. The method comprises: when a target grid fails, judging a fault level; determining a start judgment strategy of a virtual impedance based on the fault level; starting the virtual impedance based on the start judgment strategy, and performing grid forming control current limiting in a three-phase stationary coordinate system using the virtual impedance, wherein the three-phase stationary coordinate system is the basis for the grid forming control to limit the device current in the target grid within the overcurrent capability; and in the grid forming control current limiting state, controlling the voltage source type power electronic device to perform grid forming control on the target grid.

[0116] In another aspect, the present application also provides a computer program product, which comprises a computer program, the computer program can be stored on a non-transitory computer readable storage medium, and the computer program is executed by a processor, so that the computer can execute the grid forming control method of the voltage source type power electronic device provided by the above-mentioned methods. The method comprises: when a target grid fails, judging a fault level; determining a start judgment strategy of a virtual impedance based on the fault level; starting the virtual impedance based on the start judgment strategy, and performing grid forming control current limiting in a three-phase stationary coordinate system using the virtual impedance, wherein the three-phase stationary coordinate system is the basis for the grid forming control to limit the device current in the target grid within the overcurrent capability; and in the grid forming control current limiting state, controlling the voltage source type power electronic device to perform grid forming control on the target grid.

[0117] The device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed to multiple network units. Part or all of the modules can be selected to achieve the purposes of the embodiments according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0118] Through the description of the above embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software and the necessary general hardware platform, and of course can also be realized by hardware. Based on such understanding, the above technical solutions can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiments.

[0119] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for controlling a network of voltage source type power electronic equipment, characterized in that: include: When a fault occurs in the target power grid, determine the fault level; Determining a startup judgment strategy for virtual impedance based on the fault level; Starting the virtual impedance based on the startup judgment strategy, and using the virtual impedance to perform network control current limiting in a three-phase stationary coordinate system, wherein the three-phase stationary coordinate system is the basis for network control to limit the current of the equipment in the target power grid to within the overcurrent capacity; The starting of the virtual impedance based on the starting judgment strategy and the use of the virtual impedance to perform network control and current limiting in a three-phase stationary coordinate system include: After the virtual impedance is activated, a virtual voltage drop is superimposed on the potential voltage in the three-phase stationary coordinate system of the target power grid, and the current passing through the device in the target power grid is limited by the virtual voltage drop corresponding to the virtual impedance; The limiting the current passing through the device in the target power grid by using the virtual voltage drop corresponding to the virtual impedance includes: Calculating a voltage drop generated by the virtual impedance; determining a corresponding virtual voltage drop based on the voltage drop generated by the virtual impedance, and generating a target modulation wave based on the virtual voltage drop; Controlling the switching action of the voltage source type power electronic device based on the target modulation wave to control the output current and voltage; Limiting the current passing through the device in the target power grid by the voltage output by the voltage source power electronic device; In the grid-forming control current limiting state, the voltage source power electronic device is controlled to perform grid-forming control on the target grid, and three-phase virtual voltage is generated according to virtual impedance to achieve the current limiting purpose.

2. The method according to claim 1, characterized in that When a fault occurs in the target power grid, determining the fault level includes: Detecting the instantaneous value of the three-phase alternating current and the modulus of the positive sequence component of the three-phase alternating voltage of the target power grid; If the instantaneous current value is greater than or equal to the preset equipment overcurrent setting value or the voltage positive sequence component modulus is less than the first-level fault positive sequence voltage setting value, the fault level is determined to be a first-level fault; Detecting the effective value of the three-phase AC voltage of the target power grid; If the voltage positive sequence component modulus or voltage effective value is between the target power grid normal operation lower limit and the preset positive sequence voltage or voltage effective value, the fault level is determined to be a secondary fault.

3. The method according to claim 1 or 2, characterized in that The startup judgment strategy for determining the virtual impedance based on the fault level includes: If the fault level is determined to be a level one fault, the virtual impedance is immediately activated. The activation judgment strategy is to activate the virtual impedance based on the instantaneous current value or voltage criterion. If the fault level is determined to be a level 2 fault, the startup judgment strategy is to start the virtual impedance through voltage judgment.

4. The method according to claim 1, wherein The method further comprises: During the process of controlling the voltage source type power electronic device to perform network control for the target power grid, continuously monitoring changes in current and voltage; The virtual impedance is dynamically adjusted based on the changes in the current and voltage.

5. The method according to claim 1, wherein The method further comprises: The value of the virtual impedance is determined based on the overcurrent capability of the voltage source power electronic device.

6. A network control device for a voltage source type power electronic device, characterized in that: include: A judgment module is used to judge the fault level when a fault occurs in the target power grid; A determination module, configured to determine a startup judgment strategy for a virtual impedance based on the fault level; A control module, configured to start the virtual impedance based on the start-up judgment strategy and use the virtual impedance to perform network control current limiting in a three-phase static coordinate system, wherein the three-phase static coordinate system is the basis for network control to limit the current of equipment in the target power grid to within the overcurrent capacity; starting the virtual impedance based on the start-up judgment strategy and using the virtual impedance to perform network control current limiting in the three-phase static coordinate system includes: after starting the virtual impedance, superimposing a virtual voltage drop on the potential voltage in the three-phase static coordinate system of the target power grid, and limiting the current passing through the equipment in the target power grid by the virtual voltage drop corresponding to the virtual impedance; limiting the current passing through the equipment in the target power grid by the virtual voltage drop corresponding to the virtual impedance includes: calculating the voltage drop generated by the virtual impedance; determining the corresponding virtual voltage drop based on the voltage drop generated by the virtual impedance, and generating a target modulation wave based on the virtual voltage drop; controlling the switching action of the voltage source power electronic device based on the target modulation wave to control the output current and voltage; and limiting the current passing through the equipment in the target power grid by the voltage output of the voltage source power electronic device; The control module is further configured to control the voltage source power electronic device to perform network control on the target power grid in a network control current limiting state.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the grid control method of the voltage source power electronic device according to any one of claims 1 to 5 is implemented.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the grid-building control method of the voltage source power electronic device according to any one of claims 1 to 5 is implemented.

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