Network-constructed converter direct-current side voltage control method, device, equipment and storage medium

Abstract

The application provides a network-constructed converter DC side voltage control method, device, equipment and storage medium, the method comprises the following steps: when the grid voltage drops, the d / q axis component of the AC side output current is obtained, and the deviation of the module length thereof and the reference current is calculated. If the deviation is greater than zero, a positive virtual resistance and a negative virtual reactance proportional to the deviation are generated. According to this, the d-axis compensation amount (positive virtual resistance x d-axis component-negative virtual reactance x q-axis component) and the q-axis compensation amount (positive virtual resistance x q-axis component+ negative virtual reactance x d-axis component) are calculated, and the voltage loop is injected to change the output voltage to lift the active power. The method generates virtual impedance compensation by real-time detection of current deviation, overcomes the transient lag of traditional PI regulation, and effectively suppresses the DC side voltage rise after the grid drop.

Description

Technical Field

[0001] This application belongs to the field of data monitoring, and in particular relates to a method, device, equipment and storage medium for controlling the DC side voltage of a grid-type converter. Background Technology

[0002] With the advancement of the "dual carbon" target, an increasing number of new energy sources are being connected to the power grid via voltage source converters. Traditional converters employ grid-connected control, a strategy based on phase-locked loops (PLLs). However, as the scale of grid connection increases, this strategy, unable to provide inertia support, poses many challenges to the stable operation of the system. To ensure the stable operation of the power system, grid-connected converters play a crucial role due to their frequency support and voltage regulation capabilities.

[0003] In existing technologies, DC-side voltage control mostly employs steady-state PI regulation. When the DC side of the converter operates in constant power input mode, a grid voltage drop fault can cause the DC bus voltage to become unstable, resulting in an increase in DC-side voltage. Overvoltage may trigger overvoltage protection or damage the DC-side capacitor.

[0004] In the existing technology, when the DC side voltage is controlled by the steady-state PI regulation, the response to transient energy changes is lagging, resulting in large voltage fluctuation overshoot and slow recovery. Therefore, it is impossible to effectively maintain the stability of the DC side voltage after a grid voltage drop fault. Summary of the Invention

[0005] The purpose of this application is to overcome the deficiencies in the prior art and provide a method, apparatus, device and storage medium for controlling the DC side voltage of a grid converter.

[0006] This application provides a method for controlling the DC-side voltage of a grid-type converter, including:

[0007] When the grid voltage drops, the d-axis and q-axis components of the AC side output current of the grid-connected converter are obtained;

[0008] Based on the d-axis component and the q-axis component, calculate the deviation between the magnitude of the AC side output current and the reference current;

[0009] When the deviation is greater than zero, a positive virtual resistance and a negative virtual reactance are generated based on the deviation, wherein the positive virtual resistance is proportional to the deviation and the negative virtual reactance is proportional to the deviation.

[0010] Based on the positive virtual resistance, the negative virtual reactance, the d-axis component, and the q-axis component, calculate the d-axis voltage compensation and the q-axis voltage compensation. The d-axis compensation is calculated by subtracting the product of the negative virtual reactance and the q-axis component from the product of the positive virtual resistance and the d-axis component. The q-axis compensation is calculated by adding the product of the positive virtual resistance and the q-axis component to the product of the negative virtual reactance and the d-axis component.

[0011] The d-axis voltage compensation and the q-axis voltage compensation are injected into the voltage loop of the grid converter to change the output voltage of the grid converter, thereby increasing the output active power of the grid converter.

[0012] Optionally, before generating the positive virtual resistance and negative virtual reactance based on the deviation, the method further includes:

[0013] Set the proportional coefficient of the negative virtual reactance to zero;

[0014] Starting from zero, the proportional coefficient of the positive virtual resistance is gradually increased. Each time the proportional coefficient of the positive virtual resistance is increased, the difference in active power on the corresponding power angle curve is obtained.

[0015] The scaling factor of the positive virtual resistance that minimizes the difference in active power is selected as the scaling factor of the positive virtual resistance.

[0016] Optionally, before generating the positive virtual resistance and negative virtual reactance based on the deviation, the method further includes:

[0017] When the proportional coefficient of the positive virtual resistance has been selected, the proportional coefficient of the negative virtual reactance is gradually reduced from zero. Each time the proportional coefficient of the negative virtual reactance is reduced, the difference in active power on the corresponding power angle curve and the output current of the grid-type converter are obtained.

[0018] The proportional coefficient of the negative virtual reactance that minimizes the difference in active power and does not increase the output current is selected as the proportional coefficient of the negative virtual reactance.

[0019] Optionally, generating positive virtual resistance and negative virtual reactance based on the deviation includes:

[0020] A virtual inductance is generated based on the deviation, and the virtual inductance is proportional to the deviation;

[0021] The negative virtual reactance is generated by multiplying the virtual inductance by the rated angular frequency of the power grid.

[0022] The positive virtual resistance is generated based on the deviation.

[0023] Optionally, injecting the d-axis voltage compensation and the q-axis voltage compensation into the voltage loop of the grid converter includes:

[0024] Obtain the original d-axis voltage reference value and the original q-axis voltage reference value of the voltage loop;

[0025] The d-axis voltage compensation value is added to the original d-axis voltage reference value to generate a new d-axis voltage reference value;

[0026] The q-axis voltage compensation is added to the original q-axis voltage reference value to generate a new q-axis voltage reference value;

[0027] The new d-axis voltage reference value and the new q-axis voltage reference value are input into the controller of the voltage loop.

[0028] Optionally, it also includes:

[0029] When the deviation is not greater than zero, both the positive virtual resistance and the negative virtual reactance are set to zero.

[0030] Optionally, generating positive virtual resistance and negative virtual reactance based on the deviation includes:

[0031] A predetermined fixed constant is used as the scaling factor for the positive virtual resistance and the scaling factor for the negative virtual reactance, and the fixed constant remains unchanged during the operation of the grid-type converter.

[0032] This application also provides a DC-side voltage control device for a grid-type converter, comprising:

[0033] The acquisition module acquires the d-axis and q-axis components of the AC side output current of the grid-connected converter when the grid voltage drops.

[0034] The calculation module calculates the deviation between the magnitude of the AC side output current and the reference current based on the d-axis component and the q-axis component.

[0035] The parameter module generates a positive virtual resistance and a negative virtual reactance based on the deviation when the deviation is greater than zero. The positive virtual resistance is proportional to the deviation, and the negative virtual reactance is proportional to the deviation.

[0036] The compensation module calculates the d-axis voltage compensation amount and the q-axis voltage compensation amount based on the positive virtual resistance, the negative virtual reactance, the d-axis component, and the q-axis component. The d-axis compensation amount is the product of the positive virtual resistance and the d-axis component minus the product of the negative virtual reactance and the q-axis component. The q-axis compensation amount is the product of the positive virtual resistance and the q-axis component plus the product of the negative virtual reactance and the d-axis component.

[0037] The control module injects the d-axis voltage compensation amount and the q-axis voltage compensation amount into the voltage loop of the grid converter to change the output voltage of the grid converter, thereby increasing the output active power of the grid converter.

[0038] This application also provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-described method.

[0039] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the above-described method.

[0040] The beneficial effects of this application are:

[0041] This application provides a DC-side voltage control method for a grid-connected converter, comprising: acquiring the d-axis and q-axis components of the AC-side output current of the grid-connected converter when the grid voltage drops; calculating the deviation between the magnitude of the AC-side output current and a reference current based on the d-axis and q-axis components; generating a positive virtual resistance and a negative virtual reactance based on the deviation when the deviation is greater than zero, wherein the positive virtual resistance is proportional to the deviation and the negative virtual reactance is proportional to the deviation; and calculating the magnitude of the AC-side output current and the reference current based on the d-axis and q-axis components. The virtual reactance, the d-axis component, and the q-axis component are used to calculate the d-axis voltage compensation and q-axis voltage compensation. The d-axis compensation is calculated by subtracting the product of the negative virtual reactance and the q-axis component from the product of the positive virtual resistance and the d-axis component. The q-axis compensation is calculated by adding the product of the positive virtual resistance and the q-axis component to the product of the negative virtual reactance and the d-axis component. These d-axis and q-axis voltage compensations are injected into the voltage loop of the grid-connected converter to change its output voltage, thereby increasing the active power output of the grid-connected converter. This application overcomes the lag in transient response of traditional PI regulation by real-time detection of AC side current deviation to generate positive and negative virtual resistance and reactance, and injects their compensation into the voltage loop to increase the converter's output active power. This effectively suppresses the rise in DC side voltage after a grid voltage dip fault. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the DC-side control circuit of the grid converter for current limiting control in this application;

[0043] Figure 2 This is a schematic diagram of the DC-side voltage control process of the grid-type converter in this application;

[0044] Figure 3 This is a schematic diagram of the equivalent circuit for virtual impedance control in this application;

[0045] Figure 4 This is a vector diagram of parameters under virtual impedance control in this application;

[0046] Figure 5 This is a schematic diagram of the virtual impedance control effect on the voltage loop in this application;

[0047] Figure 6 This is the work angle curve diagram in this application;

[0048] Figure 7 These are the converter output active power curves under different virtual impedance amplification factors in this application;

[0049] Figure 8 This is a curve showing the change of phase angle and phase angle derivative under grid voltage fault conditions in this application;

[0050] Figure 9 This is the DC-side voltage change curve under grid voltage fault conditions in this application;

[0051] Figure 10 It is in this application Curves showing the changes in DC-side voltage and output active power;

[0052] Figure 11 Is it in this application? The curves showing the changes in DC-side voltage and output active power;

[0053] Figure 12 It is in this application The curves showing the changes in DC-side voltage and output active power. Detailed Implementation

[0054] Exemplary embodiments of the present disclosure will now be provided in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it is to be understood that the various forms of disclosure should not be limited to the embodiments set forth in this application. Rather, the embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0055] This application provides a DC-side voltage control method for a grid-type converter, applied in the field of power electronics technology. The method first establishes a simplified circuit model and control strategy for the grid-type converter, obtaining the output power function, DC-side dynamic function, and droop control function, and then establishes a large-signal model. A virtual impedance control signal is added to the voltage loop. Then, based on the impact of the control strategy on power after adding the virtual impedance, the active power function is updated, and the large-signal model is updated. The value of the virtual impedance is designed based on the large-signal model, and the impact of transient faults on the DC-side voltage is analyzed. This verifies that the virtual impedance can control the grid-type converter and adaptively improve the stability of the DC-side voltage after a fault.

[0056] This application does not require any additional circuit components; it improves the DC-side voltage stability of the grid converter simply by changing the control method, thereby improving system stability without increasing costs.

[0057] The problem this application aims to solve is that when the DC side of the converter operates in constant power input mode, the DC bus voltage cannot remain stable after a grid voltage drop fault, resulting in an increase in DC side voltage. Overvoltage may trigger overvoltage protection or damage the DC side capacitor. Therefore, maintaining a stable DC side voltage after a transient event is crucial for maintaining system stability.

[0058] The beneficial effects of this application are as follows:

[0059] 1. By adding virtual impedance control to the voltage loop, the rise in DC-side capacitor voltage of the converter during transients can be mitigated;

[0060] 2. By using the change in AC current to obtain the value of the virtual impedance, the problem of DC-side capacitor voltage rise in the converter after transients can be adaptively mitigated; 3. No additional circuit components are required, making the modification difficult, cost-effective, and easy to promote. In existing technologies, DC-side voltage control mostly adopts steady-state PI regulation, which lags in response to transient energy changes, resulting in large voltage fluctuation overshoot and slow recovery; this application uses virtual impedance control to control the output voltage amplitude and phase angle of the converter, which can solve the problem of transient voltage runaway.

[0061] like Figure 1 The diagram shows a simplified circuit model of the grid-type converter, including the converter output port, lines, and grid bus, comprising a constant power supply, a three-phase bridge converter, and a low-pass output LC filter (including the filter inductor). and filter capacitor ), current limiting control, and droop control with filtering, including active and reactive loops, i.e. Figure 1 The Pf control and QV control, and voltage and current dual closed-loop control are used.

[0062] The DC side provides input active power through a constant power supply. The power is inverted into AC power by a three-phase bridge converter, and then filtered out for high-frequency harmonics by a low-pass output LC filter before being supplied to the power grid via transmission lines. and output reactive power Ultimately, this achieves DC-AC energy conversion and grid connection.

[0063] based on Figure 1 The DC-side voltage control of the grid-type converter based on virtual impedance control is explained in detail below with specific implementation steps.

[0064] Please refer to Figure 2 As shown, a DC-side voltage control method for a grid-type converter includes:

[0065] S101. When the grid voltage drops, obtain the d-axis and q-axis components of the AC side output current of the grid-type converter.

[0066] When a voltage drop fault occurs in the power grid, the components of the AC output current value of the converter on the d-axis and q-axis after the fault are obtained. and These two components are used to assess the severity of the fault and generate corresponding control signals.

[0067] Before obtaining the current component, it is necessary to establish a simplified circuit model and control strategy for the grid-type converter, obtain the power function, DC-side dynamic function and droop control function of the grid-type converter, and establish a large-signal model.

[0068] Ignoring power losses in converter components, design the DC-side dynamic function based on the converter's input and output power:

[0069] .

[0070] in, The output active power of the converter. For DC side capacitors, DC side voltage It is the input active power on the DC side of the converter.

[0071] A simplified circuit model of the converter output port-line-grid bus of the grid-type converter is established, and the large-signal model of the converter is derived based on the simplification.

[0072] .

[0073] in, The output reactive power of the converter, and These are the active power reference value and the reactive power reference value, respectively. and These are the cutoff angular frequencies of the low-pass filters on the active and reactive branches, respectively. and These are the droop coefficients for the active and reactive power branches, respectively. These are the rated voltages.

[0074] S102. Calculate the deviation between the magnitude of the AC side output current and the reference current based on the d-axis component and the q-axis component.

[0075] Calculate the magnitude of the AC output current, i.e.:

[0076] .

[0077] Then, this module length is compared with the set maximum reference value of the DC-side output current during operation. Compare the two and calculate the difference, which is denoted as . .

[0078] The calculation formula is as follows:

[0079] .

[0080] This deviation This reflects the degree to which the current deviates from the normal operating range after a fault, and is a key variable for the subsequent generation of virtual impedance. In constant power control mode, the input active power... Since it is a constant, the active power difference The larger the voltage, the greater the change in DC-side voltage. Using virtual impedance control can control the output active power after a converter fault. This reduces the active power difference, thereby reducing DC-side voltage fluctuations.

[0081] like Figure 6 As shown, after a voltage dip in the grid, the stable operating point shifts from point a to point b, and the converter outputs active power at point b. Less than the input active power , Therefore, before reaching the new equilibrium operating point b, the input active power... A portion of the power continuously flows to the DC-side capacitor, and the charging of the DC-side capacitor causes its voltage to rise.

[0082] Furthermore, from the DC-side dynamic function, we can obtain:

[0083] .

[0084] In constant power control mode Since it is a constant, the active power difference The larger the voltage, the greater the change in DC-side voltage. Using virtual impedance control can control the output active power after a converter fault. This reduces the active power difference, thereby reducing DC-side voltage fluctuations.

[0085] S103. When the deviation is greater than zero, a positive virtual resistance and a negative virtual reactance are generated according to the deviation, wherein the positive virtual resistance is proportional to the deviation and the negative virtual reactance is proportional to the deviation.

[0086] when When the output current exceeds the reference value, virtual impedance control is activated.

[0087] Virtual resistance and virtual inductance It is based on deviation The generated data is as follows:

[0088] ;

[0089] .

[0090] in, and These are the amplification factors for the virtual resistance and virtual reactance, respectively.

[0091] This generated It is a positive value, that is, a positive virtual resistance; while virtual reactance The calculation formula is Since the virtual reactance needs to be negative in subsequent designs to achieve the control effect, therefore here... It will be designed to be negative, thus generating It is negative, which in turn makes If it is negative, it is a negative virtual reactance.

[0092] If the deviation If it is not greater than zero, then the positive virtual resistance will be... and the negative virtual reactance Set all to zero.

[0093] In other words, when hour, and At this point, virtual impedance control is ineffective.

[0094] Furthermore, virtual impedance control is established, and the value of the virtual impedance is:

[0095] .

[0096] in, For virtual inductance, and These represent the d-axis and q-axis components of the AC output current of the converter after a fault. and These are the amplification factors for virtual resistance and virtual reactance, respectively. This is the reference value for the DC-side output current during steady-state operation.

[0097] like Figure 3 As shown, the components of the virtual impedance added to the d and q axes of the voltage loop are derived, so that they achieve the same effect as the actual impedance connected at the converter output port:

[0098] .

[0099] in, , These are the values ​​for the d and q axes of the input voltage loop, respectively.

[0100] like Figure 4 As shown, the function of the virtual impedance is to reduce the output voltage of the droop control circuit. Transformed through virtual impedance control .like Figure 5 As shown, after adding virtual impedance control, the phase angle and amplitude of the converter output voltage change, thereby changing the output power of the converter.

[0101] according to Figure 4 The impact of the virtual impedance control strategy on the output power is calculated using vector decomposition to determine the output power of the converter after adding virtual impedance, and the power function is updated accordingly.

[0102] .

[0103] in , These are virtual resistance and virtual reactance, respectively, whose values ​​are controlled by the output current on the AC side. The active power output of the converter under virtual impedance control. This refers to the reactive power output of the converter under virtual impedance control.

[0104] Update the large-signal model based on the updated power function:

[0105]

[0106] The simulation code of the system can be established through the large-signal model. The simulation code can verify the feasibility of the proposed virtual impedance in principle, and the parameter values ​​of the virtual impedance can be designed through the simulation curve.

[0107] S104. Based on the positive virtual resistance, the negative virtual reactance, the d-axis component, and the q-axis component, calculate the d-axis voltage compensation and the q-axis voltage compensation. The d-axis voltage compensation is (positive virtual resistance * d-axis component) - (negative virtual reactance * q-axis component), and the q-axis voltage compensation is (positive virtual resistance * q-axis component) + (negative virtual reactance * d-axis component).

[0108] Specifically, in order to achieve the same effect as the actual impedance connected at the converter output port, it is necessary to derive the components of the virtual impedance added to the d and q axes of the voltage loop.

[0109] These components are the d-axis voltage compensation quantities. and q-axis voltage compensation .

[0110] Their calculation formulas are as follows:

[0111] ;

[0112] .

[0113] in, and These are virtual resistance and virtual reactance, respectively, whose values ​​are controlled by the output current on the AC side. The function of the virtual impedance is to reduce the output voltage of the droop control circuit. Transformed through virtual impedance control After adding virtual impedance control, the phase angle and amplitude of the converter output voltage change, thereby changing the output power of the converter.

[0114] S105. Inject the d-axis voltage compensation amount and the q-axis voltage compensation amount into the voltage loop of the grid converter to change the output voltage of the grid converter, thereby increasing the output active power of the grid converter.

[0115] The calculated d-axis voltage compensation amount and q-axis voltage compensation The original d-axis voltage reference value and the original q-axis voltage reference value of the voltage loop are added to generate new d-axis voltage reference values ​​and new q-axis voltage reference values, respectively.

[0116] These two new voltage reference values ​​are then input into the voltage loop controller to adjust the converter output voltage.

[0117] In this way, the output power of the converter can be changed.

[0118] Based on the impact of the virtual impedance control strategy on the output power, the vector decomposition method is used to calculate the output power of the converter after adding virtual impedance, and the updated power function is:

[0119] ;

[0120] .

[0121] in, The active power output of the converter under virtual impedance control. This refers to the reactive power output of the converter under virtual impedance control.

[0122] By adjusting the virtual impedance, the output active power of the converter after a fault can be increased, thereby reducing the active power difference. This effectively alleviates the problem of rising DC-side capacitor voltage.

[0123] Before generating positive virtual resistance and negative virtual reactance based on the aforementioned deviation, the scaling factors for virtual resistance and virtual reactance need to be designed.

[0124] The proportionality coefficient of the negative virtual reactance Set it to zero, and gradually increase the scaling factor of the positive virtual resistance from zero. The value increases each time Then, the difference in active power on the corresponding power angle curve is obtained, and the value that minimizes the difference in active power is selected. The value is used as the scaling factor for the positive virtual resistance.

[0125] This is because the selected virtual resistance value needs to reduce the active power difference of the converter output power in order to reduce the drop in DC side capacitor voltage.

[0126] With the proportional coefficient of the positive virtual resistance already selected, the proportional coefficient of the negative virtual reactance is gradually decreased starting from zero. The value decreases each time Then, the difference in active power on the corresponding power angle curve and the output current of the grid-type converter are obtained, and the converter is selected to minimize the difference in active power and prevent the output current from increasing. The value is used as the scaling factor for the negative virtual reactance.

[0127] This is to prevent the converter output current from increasing. Through the above design, suitable virtual impedance parameters can be obtained.

[0128] To prevent the addition of virtual impedance from increasing the fault current, the value of the virtual impedance needs to be limited. The converter's output current value is:

[0129] .

[0130] in, This is the output voltage of the converter. This is the grid voltage. and The voltage vector difference between them is , This represents the current in the line.

[0131] Since the line reactance is much greater than the resistance, the value of the resistance is ignored, and we get:

[0132] .

[0133] in, The value is With line reactance The angle difference.

[0134] From the above equation, we can see that, let If the value of the virtual impedance remains unchanged, the output current of the converter will remain unchanged. To achieve this effect, the virtual impedance needs to be set to positive and the virtual reactance needs to be set to negative.

[0135] The code for running a large-signal model in MATLAB allows you to obtain different power angle curves by changing the parameters of the virtual impedance in the model.

[0136] like Figure 7 As shown, the dashed line represents the power angle curve with virtual impedance control added, during a grid voltage drop fault. Design in PU case The value of the virtual reactance is gradually decreased by the amplification factor. The value, with the dashed line rising in the direction of the arrow, indicates that the converter output power value has increased after a grid voltage drop fault.

[0137] Depend on Figure 7 It is evident that an excessively large virtual impedance will result in ineffective control, while an excessively small virtual impedance will lead to excessively high output power, causing the output power to exceed the input power and resulting in a drop in DC-side voltage. Therefore, the value of the virtual impedance should be chosen so that the new equilibrium point is close to the equilibrium point before the fault, reducing the fluctuation of output power and thus reducing the fluctuation of DC-side capacitor voltage. The design of the value selection is similar.

[0138] Based on the selected virtual impedance parameters, the function curves of the phase angle derivative and phase angle of the system under virtual impedance control are obtained, such as... Figure 8 As shown, when virtual impedance control is added, the change in phase angle is suppressed, so the system can reach the equilibrium point more quickly and reduce the fluctuation of DC side capacitor voltage caused by power imbalance.

[0139] like Figure 9 As shown, the DC-side voltage fluctuation is improved after adding a virtual impedance.

[0140] To verify the superiority of this solution, simulation analysis was performed in MATLAB / Simulink, and the system parameters are shown in Table 1.

[0141] Depend on Figure 10 Figures 11 and 12 show the changes in the DC-side voltage and output power of the converter after a grid voltage fault.

[0142] Figure 10 For the occurrence The parameter changes after a PU fault are related to the value of the virtual impedance, which is related to the current value after the fault. The larger the fault current, the larger the virtual impedance. When the grid voltage drops to 0.8 PU, the change in fault current is small, so the role of virtual impedance is small. Therefore, whether or not there is virtual impedance control has little impact on the output power of the converter. Consequently, the difference in DC side voltage change caused by power change is also not significant.

[0143] When the degree of failure increases further When the fault current increases, the value of the virtual impedance also increases. Therefore, after a circuit fault occurs, the output power of the converter increases under the control of the virtual impedance, resulting in a smaller voltage rise on the DC side.

[0144] When the degree of failure is large, that is When the fault current increases, the value of the virtual impedance increases further, so the impact of the virtual impedance on the active power output of the converter increases significantly.

[0145] Depend on Figure 11 It can be seen that without virtual impedance, the active power of the converter drops sharply. However, under the control of virtual impedance, the change in active power is not significant compared to the reference value. The change in active power directly affects the DC bus voltage. The difference in DC bus voltage under the two control methods is significant. The change in DC bus voltage of the converter under virtual impedance control is small, while the increase in DC bus voltage of the converter without virtual impedance control is large.

[0146] according to Figure 10 , Figure 11 and Figure 12 It can be concluded that virtual impedance does not affect the DC bus voltage under minor fault conditions, but as the fault deepens, virtual impedance can significantly reduce the fluctuation of DC bus voltage.

[0147] Table 1 System Parameters:

[0148]

[0149] In one specific embodiment, the system parameters can be set as follows:

[0150] Rated voltage is 100V, DC side voltage 460V, active power reference value 1kW, input active power 1kW, rated frequency 50Hz, DC side capacitor The line inductance is 3mF. The line resistance is 7mH. 1mΩ, output reference current 10A, virtual resistance amplification factor The virtual reactance amplification factor is 1.5. It is -0.004.

[0151] This application also provides a DC-side voltage control device for a grid-type converter, comprising:

[0152] The acquisition module acquires the d-axis and q-axis components of the AC side output current of the grid-connected converter when the grid voltage drops.

[0153] The calculation module calculates the deviation between the magnitude of the AC side output current and the reference current based on the d-axis component and the q-axis component.

[0154] The parameter module generates a positive virtual resistance and a negative virtual reactance based on the deviation when the deviation is greater than zero. The positive virtual resistance is proportional to the deviation, and the negative virtual reactance is proportional to the deviation.

[0155] The compensation module calculates the d-axis voltage compensation amount and the q-axis voltage compensation amount based on the positive virtual resistance, the negative virtual reactance, the d-axis component, and the q-axis component. The d-axis compensation amount is the product of the positive virtual resistance and the d-axis component minus the product of the negative virtual reactance and the q-axis component. The q-axis compensation amount is the product of the positive virtual resistance and the q-axis component plus the product of the negative virtual reactance and the d-axis component.

[0156] The control module injects the d-axis voltage compensation amount and the q-axis voltage compensation amount into the voltage loop of the grid converter to change the output voltage of the grid converter, thereby increasing the output active power of the grid converter.

[0157] This application also provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-described method.

[0158] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the above-described method.

[0159] The above embodiments are provided to enable those skilled in the art to understand and apply this application. Those skilled in the art will readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without inventive effort. Therefore, this application is not limited to the above embodiments, and any improvements and modifications made to this application based on the disclosure thereof should be within the scope of protection of this application.

Claims

1. A method for controlling the DC-side voltage of a grid-connected converter, characterized in that, include: When the grid voltage drops, the d-axis and q-axis components of the AC side output current of the grid-connected converter are obtained; Based on the d-axis component and the q-axis component, calculate the deviation between the magnitude of the AC side output current and the reference current; When the deviation is greater than zero, a positive virtual resistance and a negative virtual reactance are generated based on the deviation, wherein the positive virtual resistance is proportional to the deviation and the negative virtual reactance is proportional to the deviation. Based on the positive virtual resistance, the negative virtual reactance, the d-axis component, and the q-axis component, calculate the d-axis voltage compensation and the q-axis voltage compensation. The d-axis compensation is calculated by subtracting the product of the negative virtual reactance and the q-axis component from the product of the positive virtual resistance and the d-axis component. The q-axis compensation is calculated by adding the product of the positive virtual resistance and the q-axis component to the product of the negative virtual reactance and the d-axis component. The d-axis voltage compensation and the q-axis voltage compensation are injected into the voltage loop of the grid converter to change the output voltage of the grid converter, thereby increasing the output active power of the grid converter.

2. The method according to claim 1, characterized in that, Before generating the positive virtual resistance and negative virtual reactance based on the aforementioned deviation, the process further includes: Set the proportional coefficient of the negative virtual reactance to zero; Starting from zero, the proportional coefficient of the positive virtual resistance is gradually increased. Each time the proportional coefficient of the positive virtual resistance is increased, the difference in active power on the corresponding power angle curve is obtained. The scaling factor of the positive virtual resistance that minimizes the difference in active power is selected as the scaling factor of the positive virtual resistance.

3. The method according to claim 2, characterized in that, Before generating the positive virtual resistance and negative virtual reactance based on the aforementioned deviation, the process further includes: When the proportional coefficient of the positive virtual resistance has been selected, the proportional coefficient of the negative virtual reactance is gradually reduced from zero. Each time the proportional coefficient of the negative virtual reactance is reduced, the difference in active power on the corresponding power angle curve and the output current of the grid-type converter are obtained. The proportional coefficient of the negative virtual reactance that minimizes the difference in active power and does not increase the output current is selected as the proportional coefficient of the negative virtual reactance.

4. The method according to claim 1, characterized in that, The step of generating positive virtual resistance and negative virtual reactance based on the deviation includes: A virtual inductance is generated based on the deviation, and the virtual inductance is proportional to the deviation; The negative virtual reactance is generated by multiplying the virtual inductance by the rated angular frequency of the power grid. The positive virtual resistance is generated based on the deviation.

5. The method according to claim 1, characterized in that, The step of injecting the d-axis voltage compensation and the q-axis voltage compensation into the voltage loop of the grid converter includes: Obtain the original d-axis voltage reference value and the original q-axis voltage reference value of the voltage loop; The d-axis voltage compensation value is added to the original d-axis voltage reference value to generate a new d-axis voltage reference value; The q-axis voltage compensation is added to the original q-axis voltage reference value to generate a new q-axis voltage reference value; The new d-axis voltage reference value and the new q-axis voltage reference value are input into the controller of the voltage loop.

6. The method according to claim 1, characterized in that, Also includes: When the deviation is not greater than zero, both the positive virtual resistance and the negative virtual reactance are set to zero.

7. The method according to claim 1, characterized in that, The step of generating positive virtual resistance and negative virtual reactance based on the deviation includes: A predetermined fixed constant is used as the scaling factor for the positive virtual resistance and the scaling factor for the negative virtual reactance, and the fixed constant remains unchanged during the operation of the grid-type converter.

8. A DC-side voltage control device for a grid-type converter, characterized in that, include: The acquisition module acquires the d-axis and q-axis components of the AC side output current of the grid-connected converter when the grid voltage drops. The calculation module calculates the deviation between the magnitude of the AC side output current and the reference current based on the d-axis component and the q-axis component. The parameter module generates a positive virtual resistance and a negative virtual reactance based on the deviation when the deviation is greater than zero. The positive virtual resistance is proportional to the deviation, and the negative virtual reactance is proportional to the deviation. The compensation module calculates the d-axis voltage compensation amount and the q-axis voltage compensation amount based on the positive virtual resistance, the negative virtual reactance, the d-axis component, and the q-axis component. The d-axis compensation amount is the product of the positive virtual resistance and the d-axis component minus the product of the negative virtual reactance and the q-axis component. The q-axis compensation amount is the product of the positive virtual resistance and the q-axis component plus the product of the negative virtual reactance and the d-axis component. The control module injects the d-axis voltage compensation amount and the q-axis voltage compensation amount into the voltage loop of the grid converter to change the output voltage of the grid converter, thereby increasing the output active power of the grid converter.

9. An electronic device, characterized in that, It includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores a computer program that, when executed in a computer, causes the computer to perform the method described in any one of claims 1 to 7.

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