Network construction control method and system of static var generator without super capacitor

Abstract

The invention provides a network construction control method and system for a static var generator without a super capacitor, and the method comprises the steps: obtaining a variable needed by the control of the static var generator, comprise a three-phase bridge arm voltage measurement value, a three-phase bridge arm voltage instruction value, a reactive power instruction value, an alternating voltage amplitude instruction value, an output reactive power measurement value, an output alternating current measurement value, an alternating voltage amplitude measurement value of a common coupling point, a direct-axis voltage measurement value and a quadrature-axis voltage measurement value; obtaining a three-phase modulation voltage through a voltage loop and an alternating current loop according to variables required by control and based on direct current voltage-frequency-phase control and reactive power-voltage droop control; and obtaining a switch tube control signal according to the three-phase modulation voltage, and completing network construction control of the static var generator according to the switch tube control signal. According to the invention, the stability of the DC voltage of the static var generator can be ensured without adding a super capacitor, and active support is provided for an AC side power grid.

Description

Technical Field

[0001] The present application relates to the technical field of grid-forming control, and particularly to a grid-forming control method and system for a static var generator without a super capacitor. Background Art

[0002] With the increase in the installed capacity of new energy and the decrease in grid strength, the problems of low inertia and weak damping in the new power system have become more prominent, and the stability problems of voltage and frequency have become increasingly obvious. In order to improve the voltage stability of the system and improve the power quality, static var generators (SVG for short) are widely used in new energy power stations. However, traditional grid-following SVG is difficult to meet the voltage support requirements in a power grid with a high penetration rate of new energy. In order to make SVG adapt to a power grid with a high penetration rate of new energy, improve the voltage support ability of SVG for the power grid, and enable it to have a certain inertia support ability, and improve the stable operation level of new energy power stations, a grid-forming control strategy needs to be adopted to control SVG.

[0003] Existing grid-forming control strategies usually assume that there is a DC source with stable power supply on the DC side, so power synchronization control can be adopted to adjust the AC side voltage amplitude and phase according to the AC side output power to achieve support for the AC side power grid. However, in fact, there is no DC source on the DC side of SVG, so the existing grid-forming control strategies cannot be directly applied to SVG. Although the voltage change on the DC side of SVG can be made smaller by adding a super capacitor on the DC side of SVG, however, configuring a super capacitor will increase the structural complexity of SVG and increase the cost, resulting in a decrease in the economic efficiency of SVG operation. Summary of the Invention

[0004] In view of at least one problem in the prior art, the present application proposes a grid-forming control method and system for a static var generator without a super capacitor, which can ensure the stability of the DC voltage of the static var generator without adding a super capacitor and provide active support to the AC side power grid.

[0005] To solve the above technical problems, the present application provides the following technical solutions:

[0006] In a first aspect, the present application provides a grid-forming control method for a static var generator without a super capacitor, including:

[0007] Obtain the variables required for the control of the static var generator, where the variables required for the control include: three-phase bridge arm voltage measurement values, three-phase bridge arm voltage command values, reactive power command values, AC voltage amplitude command values, output reactive power measurement values, output AC current measurement values, AC voltage amplitude measurement values at the point of common coupling, direct-axis voltage measurement values, and quadrature-axis voltage measurement values;

[0008] Based on the three-phase bridge arm voltage measurement values and the three-phase bridge arm voltage command values, and based on DC voltage-frequency-phase control, obtain the voltage phase input by the static var generator into the power grid;

[0009] According to the reactive power command value, the AC voltage amplitude command value, the output reactive power measurement value, and the AC voltage amplitude measurement value, through reactive-voltage droop control, obtain the direct-axis AC voltage amplitude of the static var generator;

[0010] Through the voltage loop and the AC current loop, according to the direct-axis voltage measurement value, the quadrature-axis voltage measurement value, the voltage phase input into the power grid, the output AC current measurement value, and the direct-axis AC voltage amplitude, obtain the three-phase modulation voltage;

[0011] According to the three-phase modulation voltage, obtain the switch tube control signal, and according to the switch tube control signal, complete the grid-forming control of the static var generator.

[0012] In one embodiment, the obtaining the voltage phase input by the static var generator into the power grid based on the three-phase bridge arm voltage measurement values and the three-phase bridge arm voltage command values, and based on DC voltage-frequency-phase control, includes:

[0013] Take the average value of the three-phase bridge arm voltage measurement values to obtain the measured voltage average value;

[0014] Use the difference between the measured voltage average value and the three-phase bridge arm voltage command values as the DC voltage average deviation value;

[0015] Apply the DC voltage average deviation value multiplied by the DC voltage droop coefficient to obtain the proportionally amplified DC voltage average deviation value;

[0016] Multiply the proportionally amplified DC voltage average deviation value by the reciprocal of the virtual inertia parameter simulating the rotor inertia to obtain a first intermediate quantity, pass the proportionally amplified DC voltage average deviation value through a lag differential link to obtain a second intermediate quantity, and add the first intermediate quantity and the second intermediate quantity to obtain the angular frequency change value input by the static var generator into the power grid;

[0017] Add the angular frequency change value to the rated angular frequency to obtain the angular frequency input by the static var generator into the power grid, and integrate the angular frequency to obtain the voltage phase input by the static var generator into the power grid.

[0018] In one embodiment, obtaining the direct-axis AC voltage amplitude of the static var generator via reactive power-voltage droop control based on the reactive power command value, the AC voltage amplitude command value, the measured output reactive power, and the measured AC voltage amplitude includes:

[0019] Taking the difference between the reactive power command value and the measured output reactive power as the reactive power deviation value;

[0020] Multiplying the reactive power deviation value by the reactive droop coefficient to obtain the reactive droop amount;

[0021] Taking the difference between the AC voltage amplitude command value and the measured AC voltage amplitude at the point of common coupling as the AC voltage amplitude deviation value;

[0022] Multiplying the AC voltage amplitude deviation value by the voltage droop coefficient to obtain the voltage droop amount;

[0023] Taking the difference between the reactive droop amount and the voltage droop amount, and passing it through a proportional-integral controller to obtain the direct-axis AC voltage amplitude of the static var generator.

[0024] In one embodiment, obtaining the three-phase modulation voltage through a voltage loop and an AC current loop based on the direct-axis voltage measurement value, the quadrature-axis voltage measurement value, the voltage phase input to the power grid, the measured output AC current, and the direct-axis AC voltage amplitude includes:

[0025] Taking the difference between the direct-axis AC voltage amplitude and the measured direct-axis voltage at the point of common coupling, and passing it through a proportional-integral controller to obtain the direct-axis current command;

[0026] Taking the difference between the quadrature-axis AC voltage amplitude (set to 0) and the measured quadrature-axis voltage at the point of common coupling, and passing it through a proportional-integral controller to obtain the quadrature-axis current command;

[0027] Passing the direct-axis current command and the quadrature-axis current command through a circular current limiting link to obtain the limited direct-axis current command and quadrature-axis current command;

[0028] Performing dq inverse transformation based on the limited quadrature-axis current command, direct-axis current command, and the voltage phase input to the power grid to obtain the AC current command;

[0029] Taking the difference between the AC current command and the measured output AC current, and passing it through a quasi-proportional-resonant controller to obtain the three-phase modulation voltage.

[0030] In one embodiment, passing the direct-axis current command and the quadrature-axis current command through a circular current limiting link to obtain the limited direct-axis current command and quadrature-axis current command includes:

[0031] The limited quadrature-axis current command \(i_{q}\) is obtained according to the following formula: qref and the direct-axis current command \(i_{d}\): dref :

[0032]

[0033] wherein, is the direct-axis current command, is the quadrature-axis current command, \(I_{lim}\): max is the maximum current command amplitude allowed to pass through the circular current limiting link.

[0034] In one embodiment, the transfer function expression of the quasi-proportional resonant controller is:

[0035]

[0036] where \(k_{p}\): p is the proportional coefficient of the quasi-proportional resonant controller, \(k_{r}\): r is the resonant coefficient of the quasi-proportional resonant controller, \(\omega_{c}\): c is the cut-off frequency of the resonant link of the quasi-proportional resonant controller, \(s\) is the differential operator, and \(\omega\) is the angular frequency.

[0037] In a second aspect, the present application provides a grid-forming control system for a static var generator without a super capacitor, including:

[0038] An acquisition device for acquiring the variables required for controlling the static var generator, where the variables required for control include: three-phase bridge arm voltage measurement values, three-phase bridge arm voltage command values, reactive power command values, AC voltage amplitude command values, output reactive power measurement values, output AC current measurement values, AC voltage amplitude measurement values at the point of common coupling, direct-axis voltage measurement values, and quadrature-axis voltage measurement values;

[0039] A first control device for obtaining the voltage phase input from the static var generator to the power grid based on DC voltage-frequency-phase control according to the three-phase bridge arm voltage measurement values and the three-phase bridge arm voltage command values;

[0040] A second control device for obtaining the direct-axis AC voltage amplitude of the static var generator through reactive-voltage droop control according to the reactive power command value, the AC voltage amplitude command value, the output reactive power measurement value, and the AC voltage amplitude measurement value;

[0041] A third control device for obtaining three-phase modulation voltages through a voltage loop and an AC current loop according to the direct-axis voltage measurement value, the quadrature-axis voltage measurement value, the voltage phase input to the power grid, the output AC current measurement value, and the direct-axis AC voltage amplitude;

[0042] A three-phase modulation device is used to obtain a switching tube control signal according to the three-phase modulation voltage, and complete the grid connection control of the static var generator according to the switching tube control signal.

[0043] In a third aspect, the present application provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the grid connection control method of the static var generator without a super capacitor.

[0044] In a fourth aspect, the present application provides a computer-readable storage medium, on which computer instructions are stored. When the instructions are executed by a processor, they implement the grid connection control method of the static var generator without a super capacitor.

[0045] In a fifth aspect, the present application provides a computer program product, including a computer program / instructions. When the computer program / instructions are executed by a processor, they implement the grid connection control method of the static var generator without a super capacitor.

[0046] As can be seen from the above technical solutions, the present application provides a grid connection control method and system for a static var generator without a super capacitor. Among them, the method includes: obtaining the variables required for the control of the static var generator, where the variables required for the control include: three-phase bridge arm voltage measurement values, three-phase bridge arm voltage command values, reactive power command values, AC voltage amplitude command values, output reactive power measurement values, output AC current measurement values, AC voltage amplitude measurement values at the point of common coupling, direct-axis voltage measurement values, and quadrature-axis voltage measurement values; based on the three-phase bridge arm voltage measurement values and the three-phase bridge arm voltage command values, obtaining the voltage phase input by the static var generator to the power grid based on DC voltage-frequency-phase control; based on the reactive power command value, the AC voltage amplitude command value, the output reactive power measurement value, and the AC voltage amplitude measurement value, obtaining the direct-axis AC voltage amplitude of the static var generator through reactive-voltage droop control; through the voltage loop and the AC current loop, obtaining three-phase modulation voltages according to the direct-axis voltage measurement value, the quadrature-axis voltage measurement value, the voltage phase input to the power grid, the output AC current measurement value, and the direct-axis AC voltage amplitude; obtaining a switching tube control signal according to the three-phase modulation voltage, and completing the grid connection control of the static var generator according to the switching tube control signal, which can ensure the stability of the DC voltage of the static var generator without adding a super capacitor and provide active support to the AC side power grid; it can adopt an effective grid connection control strategy to ensure the stability of the DC voltage of the SVG without adding a super capacitor and provide active support to the AC side power grid at the same time, significantly improving the economy of the grid-connected SVG. Description of the Drawings

[0047] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0048] Figure 1 is the first process schematic diagram of the grid-forming control method of the static var generator without a supercapacitor in the embodiments of the present application;

[0049] Figure 2 is the topological schematic diagram of the static var generator system in the embodiments of the present application;

[0050] Figure 3 is the second process schematic diagram of the grid-forming control method of the static var generator without a supercapacitor in the embodiments of the present application;

[0051] Figure 4 is the third process schematic diagram of the grid-forming control method of the static var generator without a supercapacitor in the embodiments of the present application;

[0052] Figure 5 is the fourth process schematic diagram of the grid-forming control method of the static var generator without a supercapacitor in the embodiments of the present application;

[0053] Figure 6 is the grid-forming control block diagram of the static var generator without a supercapacitor in a specific application example of the present application.

[0054] Figure 7 is the structural schematic diagram of the grid-forming control system of the static var generator without a supercapacitor in the embodiments of the present application;

[0055] Figure 8 is the system composition schematic block diagram of the electronic device in the embodiments of the present application. Specific embodiments

[0056] In order to enable those skilled in the art to better understand the technical solutions in this specification, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0057] To solve at least one of the problems existing in the above-mentioned prior art, the embodiments of the present application provide a grid-forming control method and system for a static var generator without a supercapacitor. Based on the SVG system without a supercapacitor, a star-connected cascaded H-bridge topology can be used to connect each sub-module. The DC voltage-frequency-phase control and reactive-voltage droop control of the SVG system without a supercapacitor can be realized. The DC voltage-frequency-phase control outputs the frequency, and the reactive-voltage droop control obtains the d-axis AC voltage amplitude through the reactive power deviation and subsequent calculations. The voltage loop outputs the current command after amplitude limiting through circular current limiting, and the AC current loop uses a Quasiproportional resonance (QPR) controller to output the modulation voltage. In this solution, the DC voltage-frequency-phase control can generate the voltage phase of the static var generator input to the power grid, and this phase is the angular frequency before integration. That is to say, the SVG can be synchronized with the frequency and phase of the power grid without measuring the power grid frequency but generating the frequency independently. The problem that the traditional SVG grid-forming control faces in stabilizing the DC voltage quickly can be solved, and at the same time, the rapid stabilization of the DC voltage and the active support for the grid-forming of the AC power grid can be realized. The grid-forming control method provided by this solution can be applied to the SVG without a supercapacitor on the DC side, enabling the SVG to adapt to the power grid with high-penetration new energy and providing active support for the power grid.

[0058] Specifically, it is described through the following various embodiments.

[0059] To ensure the stability of the DC voltage of the static var generator without adding a supercapacitor and provide active support to the AC side power grid, this embodiment provides a grid-forming control method for a static var generator without a supercapacitor, where the execution entity is a grid-forming control system of the static var generator without a supercapacitor. The grid-forming control system of the static var generator without a supercapacitor includes but is not limited to a server, such as Figure 1 shown, and the method specifically includes the following content:

[0060] Step 100: Obtain the variables required for the control of the static var generator. The variables required for the control include: three-phase bridge arm voltage measurement values, three-phase bridge arm voltage command values, reactive power command values, AC voltage amplitude command values, output reactive power measurement values, output AC current measurement values, AC voltage amplitude measurement values at the point of common coupling, direct-axis voltage measurement values, and quadrature-axis voltage measurement values.

[0061] Specifically, the measured reactive power output represents the measured reactive power output of the static var generator. The static var generator is a static var generator without a super capacitor and may include: multiple links, each link including: a plurality of H-bridge circuits connected in series in sequence. One end of each link is connected, and the other end of each link is respectively connected to an AC power supply via an inductor. The H-bridge circuit can be equivalent to a sub-module. In one example, as Figure 2 shown, the SVG system is a star-connected cascaded H-bridge type SVG system. The SVG system includes the static var generator 0 described above. The static var generator 0 includes: three links 1, each link being composed of a plurality of H-bridge circuits 2 connected in series. One end of each link is connected, and the other end of each link is respectively connected to an AC power grid 4 via an inductor 3. Each H-bridge circuit includes: a capacitor 6 and four switching tubes 5. The three-phase bridge arm voltages may include: the voltages between point a and point n, between point b and point n, and between point c and point n.

[0062] Step 200: Based on the measured three-phase bridge arm voltages and the three-phase bridge arm voltage command values, and based on the DC voltage-frequency-phase control, obtain the voltage phase input by the static var generator to the power grid.

[0063] Step 300: According to the reactive power command value, the AC voltage amplitude command value, the measured output reactive power, and the measured AC voltage amplitude, obtain the direct-axis AC voltage amplitude of the static var generator via the reactive-voltage droop control.

[0064] Step 400: Through the voltage loop and the AC current loop, according to the measured direct-axis voltage, the measured quadrature-axis voltage, the voltage phase input to the power grid, the measured output AC current, and the direct-axis AC voltage amplitude, obtain the three-phase modulation voltage.

[0065] Step 500: According to the three-phase modulation voltage, obtain the switching tube control signals, and according to the switching tube control signals, complete the grid-forming control of the static var generator.

[0066] Specifically, according to the three-phase modulation voltage, the switching tube control signals of each switching tube in the static var generator can be obtained. According to the switching tube control signals of each switching tube, respective control is completed to ensure the stability of the DC voltage of the static var generator and provide active support to the AC side power grid.

[0067] To improve the reliability of determining the voltage phase input by the static var generator to the power grid, as Figure 3 shown, in one embodiment, step 200 includes:

[0068] Step 201: Take the average value of the measured three-phase bridge arm voltages to obtain the average measured voltage.

[0069] Specifically, assume that the three-phase bridge arm voltages are: V an , V bn and V cn . Then, the average measured voltage V dc can be determined as V an + V bn + V cn ) / 3.

[0070] Step 202: Use the difference between the average measured voltage and the three-phase bridge arm voltage command value as the average DC voltage deviation value.

[0071] Specifically, the average DC voltage deviation value V p = average measured voltage V dc - rated DC voltage value V dcref .

[0072] Step 203: Multiply the average DC voltage deviation value by the DC voltage droop coefficient to obtain the proportionally amplified average DC voltage deviation value.

[0073] Specifically, the proportionally amplified average DC voltage deviation value V dcp = V p × DC voltage droop coefficient k p .

[0074] Step 204: Multiply the proportionally amplified average DC voltage deviation value by the reciprocal of the virtual inertia parameter simulating the rotor inertia to obtain a first intermediate quantity, pass the proportionally amplified average DC voltage deviation value through a lag-differential link to obtain a second intermediate quantity, and add the first intermediate quantity and the second intermediate quantity to obtain the angular frequency change value input by the static var generator to the power grid.

[0075] Specifically, the angular frequency change value Δω input by the static var generator to the power grid = V dcp × 1 / k J + V dcp × k d s / (1 + Ts), where V dcp is the proportionally amplified average DC voltage deviation value, k J is the virtual inertia parameter simulating the rotor inertia, k d is a coefficient, s is the differential operator, and T is the time constant.

[0076] Step 205: Add the angular frequency change value to the rated angular frequency to obtain the angular frequency input by the static var generator to the power grid, and integrate the angular frequency to obtain the voltage phase input by the static var generator to the power grid.

[0077] Specifically, before step 201, it may further include: obtaining the voltage phase parameters of the static var generator, where the voltage phase parameters include: DC voltage droop coefficient, lag differential link, angular frequency rated value, and virtual inertia parameter simulating rotor inertia.

[0078] To improve the accuracy of determining the direct-axis AC voltage amplitude, as Figure 4 shown, in one embodiment, step 300 includes:

[0079] Step 301: Use the difference between the reactive power command value and the measured output reactive power as the reactive power deviation value.

[0080] Step 302: Multiply the reactive power deviation value by the reactive power droop coefficient to obtain the reactive power droop amount.

[0081] Specifically, in the reactive-voltage droop control, the reactive power droop part can obtain the reactive power deviation value by taking the difference between the reactive power command value Q ref and the measured output reactive power Q of the static var generator, and multiply it by the reactive power droop coefficient k q to obtain the reactive power droop amount.

[0082] Step 303: Use the difference between the AC voltage amplitude command value and the measured AC voltage amplitude at the point of common coupling as the AC voltage amplitude deviation value.

[0083] Step 304: Multiply the AC voltage amplitude deviation value by the voltage droop coefficient to obtain the voltage droop amount.

[0084] Specifically, in the voltage droop part, the AC voltage amplitude deviation value can be obtained by taking the difference between the AC voltage amplitude command value u ref and the measured AC voltage amplitude u at the point of common coupling (Point of Common Coupling, abbreviated as PCC), and multiply it by the voltage droop coefficient k pcc to obtain the voltage droop amount. v Step 305: Pass the difference between the reactive power droop amount and the voltage droop amount through a proportional-integral controller to obtain the direct-axis AC voltage amplitude of the static var generator.

[0085] Specifically, the difference between the reactive power droop amount and the voltage droop amount can be taken and passed through a PI controller to obtain the d-axis AC voltage amplitude E of the SVG

[0086] . Before step 301, it may further include: obtaining the reactive power droop coefficient and the voltage droop coefficient. d .

[0087] To improve the reliability of obtaining the three-phase modulation voltage, as Figure 5As shown, in one embodiment, step 400 includes:

[0088] Step 401: Subtract the difference between the direct-axis AC voltage amplitude and the measured direct-axis voltage at the point of common coupling from the output of a proportional-integral controller to obtain a direct-axis current command.

[0089] Specifically, in the voltage loop, on the d-axis, by subtracting the d-axis AC voltage amplitude E d from the measured d-axis voltage u d at the PCC point and passing the result through a PI controller, a d-axis current command is obtained.

[0090] Step 402: Subtract the difference between the quadrature-axis AC voltage amplitude and the measured quadrature-axis voltage at the point of common coupling from the output of a proportional-integral controller to obtain a quadrature-axis current command, where the quadrature-axis AC voltage amplitude is set to 0.

[0091] Specifically, on the q-axis, subtract the q-axis AC voltage amplitude Eq from the measured q-axis voltage uq at the PCC point and pass the result through a PI controller to obtain a q-axis current command, where the q-axis AC voltage amplitude Eq is set to 0.

[0092] Step 403: Pass the direct-axis current command and the quadrature-axis current command through a circular current limiting link to obtain the limited direct-axis current command and quadrature-axis current command.

[0093] Step 404: Perform a dq inverse transformation based on the limited quadrature-axis current command, direct-axis current command, and the phase of the voltage input to the power grid to obtain an AC current command.

[0094] Step 405: Subtract the difference between the AC current command and the measured output AC current from the output of a quasi-proportional-resonant controller to obtain a three-phase modulation voltage.

[0095] Specifically, assuming the AC current command is i aref , i bref , i cref , and the measured output AC current is i a , i b , i c ; then the three-phase modulation voltages U amod = (i aref - i a ) × G PR (s), U bmod = (i bref - i b ) × G PR (s), U cmod = (i cref - i c ) × G PR (s); the transfer function expression of the quasi-proportional-resonant controller is GPR (s) can be:

[0096]

[0097] where k p is the proportional coefficient of the quasi - proportional - resonant controller, k r is the resonant coefficient of the quasi - proportional - resonant controller, ω c is the cut - off frequency of the resonant link of the quasi - proportional - resonant controller, s is the differential operator, and ω is the angular frequency.

[0098] To improve the reliability of obtaining the limited - amplitude quadrature - axis current command and direct - axis current command, in one embodiment, step 403 includes:

[0099] Obtain the limited - amplitude quadrature - axis current command i qref and direct - axis current command i dref according to the following formula:

[0100]

[0101] where is the direct - axis current command, is the quadrature - axis current command, I max is the maximum current command amplitude allowed to pass through the circular current - limiting link.

[0102] To further illustrate the present solution, the present application provides an application example of a grid - forming control method for a static var generator without a supercapacitor. The static var generator without a supercapacitor, which adopts a star - connected cascaded H - bridge topology to connect each sub - module, realizes both DC voltage - frequency - phase control and reactive - voltage droop control through grid - forming control. The specific process is as follows:

[0103] The DC voltage - frequency - phase control obtains V dc by taking the average value of the three - phase bridge - arm voltage measurements of the static var generator, subtracts V dc from the three - phase bridge - arm voltage command value V dcref to obtain the DC voltage average deviation value; multiplies the DC voltage average deviation value by the DC voltage droop coefficient k p to obtain the proportionally amplified DC voltage average deviation value, multiplies the proportionally amplified DC voltage average deviation value by the reciprocal 1 / k J of the virtual inertia parameter k J simulating the rotor inertia, and adds to this the quantity obtained by passing the DC voltage average deviation value through a lag - differential link with a coefficient of k d Finally, the angular frequency change value Δω input by the static var generator to the power grid is obtained; then Δω is compared with the rated angular frequency ω sAdd them to obtain the angular frequency ω input by the static var generator to the power grid, and integrate ω to obtain the voltage phase θ input by the static var generator to the power grid.

[0104] In the reactive power-voltage droop control, for the reactive power droop part, by taking the difference between the reactive power command value Q ref and the measured reactive power value Q output by the static var generator, the reactive power deviation value is obtained, and it is multiplied by the reactive power droop coefficient k q to obtain the reactive power droop amount; for the voltage droop part, by taking the difference between the AC voltage amplitude command value u ref and the measured AC voltage amplitude value u at the point of common coupling pcc to obtain the AC voltage amplitude deviation value, and it is multiplied by the voltage droop coefficient k v to obtain the voltage droop amount; add the reactive power droop amount and the voltage droop amount and pass them through a PI controller to obtain the d-axis AC voltage amplitude E of the static var generator d .

[0105] The phase θ obtained by the DC voltage-frequency-phase control and the d-axis AC voltage amplitude E obtained by the reactive power-voltage droop control d are used as the inputs of the voltage loop. Finally, through the voltage loop and the AC current loop, the modulated voltage is obtained, and then through the modulation process, the drive pulses of the switching tubes of the static var generator are obtained.

[0106] Among them, the implementation process of the voltage loop can be as follows: First, on the d-axis, by taking the difference between the d-axis AC voltage amplitude E d and the measured d-axis voltage value u at the PCC point d and passing through a PI controller to obtain the d-axis current command; Second, on the q-axis, take the difference between the q-axis AC voltage amplitude E q and the measured q-axis voltage value u at the PCC point q and pass through a PI controller to obtain the q-axis current command, where the q-axis AC voltage amplitude E q is set to 0; Finally, pass the d-axis current command and the q-axis current command through circular current limiting to obtain the limited dq-axis current command i dqref .

[0107] The implementation process of the AC current loop is as follows: By performing dq inverse transformation on the limited current command i dqref using the phase θ obtained by the DC voltage-frequency-phase control, the AC current command i abcref is obtained; Take the difference between the AC current command i abcref and the measured output AC current value i abc , and then pass through a quasi-proportional-resonant controller to obtain the three-phase modulated voltages U amod , U bmod , U cmod .

[0108] The expression for circular current limiting is as follows:

[0109]

[0110] In the formula and are the current commands without amplitude limiting on the d-axis and q-axis respectively, and i dref and i qref are the current commands on the d-axis and q-axis after circular current limiting respectively, and I max is the maximum current command amplitude allowed by the circular current limiting link.

[0111] The transfer function expression of the quasi-proportional resonant controller QPR is as follows:

[0112]

[0113] Among them, k p is the proportionality coefficient of the quasi-proportional resonant controller, k r is the resonant coefficient of the quasi-proportional resonant controller, ω c is the cut-off frequency of the resonant link of the quasi-proportional resonant controller, s is the differential operator, and ω is the angular frequency.

[0114] To further illustrate this solution, the present application also provides a specific application example of the grid-forming control method of a static var generator without a supercapacitor. In this application example, as Figure 2 shown, the static var generator without a supercapacitor adopts a star-connected cascaded H-bridge SVG system topology. The three links of the SVG are respectively composed of series-connected H-bridge circuits, and the ends of the three links are connected together. The method is specifically described as follows:

[0115] 1. For the SVG to implement DC voltage-frequency-phase control and reactive-voltage droop control, as Figure 6 shown, it includes the following steps:

[0116] 1) For the DC voltage-frequency-phase control, the average value of the three-phase bridge arm voltage measurements of the static var generator is taken to obtain V dc , and the difference between V dc and the three-phase bridge arm voltage command value V dcref is calculated to obtain the DC voltage average deviation value; the DC voltage average deviation value is multiplied by the DC voltage droop coefficient k p to obtain the proportionally amplified DC voltage average deviation value, and the proportionally amplified DC voltage average deviation value is multiplied by the reciprocal 1 / k J of the virtual inertia parameter k J simulating the rotor inertia, and on this basis, the quantity is added with the lag differential link with a coefficient of k d k dThe quantity obtained by s / (1 + Ts), and finally the angular frequency change value Δω of the SVG input to the power grid is obtained.

[0117] 2) Add Δω to the rated angular frequency ω s to obtain the angular frequency ω of the SVG input to the power grid, and integrate ω to obtain the voltage phase θ of the SVG input to the power grid.

[0118] 3) In the reactive power-voltage droop control, for the reactive power droop part, by subtracting the reactive power command value Q ref from the measured reactive power Q output by the SVG, the reactive power deviation value is obtained, and it is multiplied by the reactive power droop coefficient k q to obtain the reactive power droop amount.

[0119] 4) For the voltage droop part, by subtracting the AC voltage amplitude command value u ref from the measured AC voltage amplitude u at the PCC point pcc , the AC voltage amplitude deviation value is obtained, and it is multiplied by the voltage droop coefficient k v to obtain the voltage droop amount.

[0120] 5) Subtract the reactive power droop amount from the voltage droop amount and pass it through a PI controller to obtain the d-axis AC voltage amplitude E d of the SVG.

[0121] 6) The phase θ obtained by the DC voltage-frequency-phase control and the d-axis AC voltage amplitude E obtained by the reactive power-voltage droop control d serve as the inputs of the voltage loop and the AC current loop.

[0122] 3. For the voltage loop and the AC current loop control, as Figure 6 shown, it includes the following steps:

[0123] 1) In the voltage loop, first on the d-axis, by subtracting the d-axis AC voltage amplitude E d from the measured d-axis voltage u at the PCC point d , and passing it through a PI controller to obtain the d-axis current command.

[0124] 2) On the q-axis, subtract the q-axis AC voltage amplitude E q from the measured q-axis voltage u at the PCC point q and pass it through a PI controller to obtain the q-axis current command, where the q-axis AC voltage amplitude E q is set to 0.

[0125] 3) Pass the d-axis current command and the q-axis current command through circular current limiting to obtain the limited dq-axis current command id qre f.

[0126] 4) In the AC current loop, by subtracting the limited current command idqref Perform dq inverse transformation using the phase θ obtained from DC voltage-frequency-phase control to obtain the AC current command i abcref .

[0127] 5) Subtract the measured value i of the output AC current from the AC current command i abcref and then, through QPR, obtain the three-phase modulation voltages U abc , U amod , U bmod , U cmod .

[0128] 6) The three-phase modulation voltages are further processed by a PWM modulator to obtain the control signals for the switching tubes of the star-connected cascaded H-bridge SVG, which are then used to drive the switching network; the control signals for each switching tube of the SVG are obtained by PWM modulation of the three-phase modulation voltages output by the network-forming control method of the static var generator without a supercapacitor.

[0129] From a software perspective, in order to ensure the stability of the DC voltage of the static var generator without adding a supercapacitor and provide active support to the AC side power grid, this application provides an embodiment of a network-forming control system for a static var generator without a supercapacitor that implements all or part of the content of the network-forming control method for the static var generator without a supercapacitor. Refer to Figure 7 , and the network-forming control system for the static var generator without a supercapacitor specifically includes the following content:

[0130] An acquisition device 01, which is used to acquire the variables required for controlling the static var generator, and the variables required for control include: the measured values of the three-phase bridge arm voltages, the command values of the three-phase bridge arm voltages, the reactive power command value, the AC voltage amplitude command value, the measured value of the output reactive power, the measured value of the output AC current, the measured value of the AC voltage amplitude at the point of common coupling, the direct-axis voltage measured value, and the quadrature-axis voltage measured value;

[0131] A first control device 02, which is used to obtain the voltage phase input by the static var generator to the power grid based on DC voltage-frequency-phase control according to the measured values of the three-phase bridge arm voltages and the command values of the three-phase bridge arm voltages;

[0132] A second control device 03, which is used to obtain the direct-axis AC voltage amplitude of the static var generator through reactive-voltage droop control according to the reactive power command value, the AC voltage amplitude command value, the measured value of the output reactive power, and the measured value of the AC voltage amplitude;

[0133] The third control device 04 is configured to obtain three-phase modulation voltages based on the measured direct-axis voltage value, the measured quadrature-axis voltage value, the voltage phase input to the power grid, the measured output AC current value, and the direct-axis AC voltage amplitude value through a voltage loop and an AC current loop.

[0134] The three-phase modulation device 05 is configured to obtain switching tube control signals based on the three-phase modulation voltages, and complete the grid-forming control of the static var generator according to the switching tube control signals.

[0135] In one embodiment, the first control device includes:

[0136] The averaging module is configured to average the three-phase bridge arm voltage measurement values to obtain an average measurement voltage value.

[0137] The difference calculation module is configured to use the difference between the average measurement voltage value and the three-phase bridge arm voltage command value as the DC voltage average deviation value.

[0138] The application module is configured to multiply the DC voltage average deviation value by the DC voltage droop coefficient to obtain a proportionally amplified DC voltage average deviation value.

[0139] The addition module is configured to multiply the proportionally amplified DC voltage average deviation value by the reciprocal of the virtual inertia parameter simulating the rotor inertia to obtain a first intermediate quantity, obtain a second intermediate quantity by passing the proportionally amplified DC voltage average deviation value through a lag differential link, and add the first intermediate quantity and the second intermediate quantity to obtain the angular frequency change value input from the static var generator to the power grid.

[0140] The integration module is configured to add the angular frequency change value and the rated angular frequency value to obtain the angular frequency input from the static var generator to the power grid, and integrate the angular frequency to obtain the voltage phase input from the static var generator to the power grid.

[0141] In one embodiment, the second control device includes:

[0142] The first deviation calculation module is configured to use the difference between the reactive power command value and the measured output reactive power value as the reactive power deviation value.

[0143] The first droop quantity calculation module is configured to multiply the reactive power deviation value by the reactive power droop coefficient to obtain a reactive power droop quantity.

[0144] The second deviation calculation module is configured to use the difference between the AC voltage amplitude command value and the measured AC voltage amplitude value at the point of common coupling as the AC voltage amplitude deviation value.

[0145] The second droop amount calculation module is used to multiply the AC voltage amplitude deviation value by the voltage droop coefficient to obtain the voltage droop amount;

[0146] The amplitude calculation module is used to subtract the reactive power droop amount from the voltage droop amount and then pass it through a proportional-integral controller to obtain the direct-axis AC voltage amplitude of the static var generator.

[0147] In one embodiment, the three-phase modulation device includes:

[0148] The direct-axis command determination module is used to subtract the direct-axis voltage measurement value of the common coupling point from the direct-axis AC voltage amplitude and then pass it through a proportional-integral controller to obtain the direct-axis current command;

[0149] The quadrature-axis command determination module is used to subtract the quadrature-axis voltage measurement value of the common coupling point from the quadrature-axis AC voltage amplitude and then pass it through a proportional-integral controller to obtain the quadrature-axis current command, and the quadrature-axis AC voltage amplitude is set to 0;

[0150] The limiting module is used to pass the direct-axis current command and the quadrature-axis current command through a circular current limiting link to obtain the limited direct-axis current command and quadrature-axis current command;

[0151] The inverse transformation module is used to perform dq inverse transformation according to the limited quadrature-axis current command, direct-axis current command and the voltage phase input to the power grid to obtain the AC current command;

[0152] The voltage determination module is used to subtract the output AC current measurement value from the AC current command and then pass it through a quasi-proportional-resonant controller to obtain the three-phase modulation voltage.

[0153] In one embodiment, the limiting module includes:

[0154] The limiting unit is used to obtain the limited quadrature-axis current command i qref and direct-axis current command i dref :

[0155]

[0156] where is the direct-axis current command, is the quadrature-axis current command, I max is the maximum current command amplitude allowed to pass through the circular current limiting link.

[0157] In one embodiment, the transfer function expression of the quasi-proportional-resonant controller is:

[0158]

[0159] where k pis the proportionality coefficient of the quasi-proportional-resonant controller, k r is the resonant coefficient of the quasi-proportional-resonant controller, ω c is the cut-off frequency of the resonant link of the quasi-proportional-resonant controller, s is the differential operator, and ω is the angular frequency.

[0160] The embodiment of the grid-forming control system of the static var generator without a supercapacitor provided in this specification can specifically be used to execute the processing flow of the embodiment of the grid-forming control method of the static var generator without a supercapacitor. Its functions will not be elaborated here, and reference can be made to the detailed description of the embodiment of the grid-forming control method of the static var generator without a supercapacitor.

[0161] Figure 8 is a schematic diagram of the physical structure of the electronic device provided in an embodiment of the present invention. As Figure 8 shown, the electronic device includes: a memory 801, a processor 802, and a computer program stored on the memory 801 and executable on the processor 802. When the processor 802 executes the computer program, the following method is implemented:

[0162] Obtain the variables required for the control of the static var generator. The variables required for the control include: three-phase bridge arm voltage measurement values, three-phase bridge arm voltage command values, reactive power command values, AC voltage amplitude command values, output reactive power measurement values, output AC current measurement values, AC voltage amplitude measurement values at the point of common coupling, direct-axis voltage measurement values, and quadrature-axis voltage measurement values;

[0163] Based on the three-phase bridge arm voltage measurement values and the three-phase bridge arm voltage command values, and based on DC voltage-frequency-phase control, obtain the voltage phase of the static var generator input to the power grid;

[0164] Based on the reactive power command value, the AC voltage amplitude command value, the output reactive power measurement value, and the AC voltage amplitude measurement value, obtain the direct-axis AC voltage amplitude of the static var generator through reactive-voltage droop control;

[0165] Through the voltage loop and the AC current loop, based on the direct-axis voltage measurement value, the quadrature-axis voltage measurement value, the voltage phase input to the power grid, the output AC current measurement value, and the direct-axis AC voltage amplitude, obtain the three-phase modulation voltage;

[0166] Based on the three-phase modulation voltage, obtain the switching tube control signal, and based on the switching tube control signal, complete the grid-forming control of the static var generator.

[0167] This embodiment discloses a computer program product. The computer program product includes a computer program. When the computer program is executed by a processor, the following method is implemented:

[0168] Obtain the variables required for the control of the static var generator, where the variables required for the control include: three-phase bridge arm voltage measurement values, three-phase bridge arm voltage command values, reactive power command values, AC voltage amplitude command values, output reactive power measurement values, output AC current measurement values, AC voltage amplitude measurement values at the point of common coupling, direct-axis voltage measurement values, and quadrature-axis voltage measurement values;

[0169] Based on the three-phase bridge arm voltage measurement values and the three-phase bridge arm voltage command values, and based on DC voltage-frequency-phase control, obtain the voltage phase of the static var generator input to the power grid;

[0170] Based on the reactive power command value, the AC voltage amplitude command value, the output reactive power measurement value, and the AC voltage amplitude measurement value, obtain the direct-axis AC voltage amplitude of the static var generator through reactive-voltage droop control;

[0171] Through the voltage loop and the AC current loop, based on the direct-axis voltage measurement value, the quadrature-axis voltage measurement value, the voltage phase input to the power grid, the output AC current measurement value, and the direct-axis AC voltage amplitude, obtain the three-phase modulation voltage;

[0172] Based on the three-phase modulation voltage, obtain the switching tube control signal, and based on the switching tube control signal, complete the grid-forming control of the static var generator.

[0173] This embodiment provides a computer-readable storage medium, where the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0174] Obtain the variables required for the control of the static var generator, where the variables required for the control include: three-phase bridge arm voltage measurement values, three-phase bridge arm voltage command values, reactive power command values, AC voltage amplitude command values, output reactive power measurement values, output AC current measurement values, AC voltage amplitude measurement values at the point of common coupling, direct-axis voltage measurement values, and quadrature-axis voltage measurement values;

[0175] Based on the three-phase bridge arm voltage measurement values and the three-phase bridge arm voltage command values, and based on DC voltage-frequency-phase control, obtain the voltage phase of the static var generator input to the power grid;

[0176] Based on the reactive power command value, the AC voltage amplitude command value, the output reactive power measurement value, and the AC voltage amplitude measurement value, obtain the direct-axis AC voltage amplitude of the static var generator through reactive-voltage droop control;

[0177] Through the voltage loop and the AC current loop, three-phase modulation voltages are obtained based on the measured direct-axis voltage value, the measured quadrature-axis voltage value, the voltage phase input to the power grid, the measured output AC current value, and the direct-axis AC voltage amplitude.

[0178] Based on the three-phase modulation voltages, switching tube control signals are obtained, and based on the switching tube control signals, the grid-forming control of the static var generator is completed.

[0179] Those skilled in the art should understand that the embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0180] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, and the combination of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to generate a machine, such that the instructions executed by the processors of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0181] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0182] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are performed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0183] In the description of this specification, the descriptions with reference to the terms "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0184] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A grid-forming control method for a static var generator without a supercapacitor, characterized in that, Comprising: Obtaining variables required for the control of the static var generator, where the variables required for the control include: three-phase bridge arm voltage measurement values, three-phase bridge arm voltage command values, reactive power command values, AC voltage amplitude command values, output reactive power measurement values, output AC current measurement values, AC voltage amplitude measurement values at the point of common coupling, direct-axis voltage measurement values, and quadrature-axis voltage measurement values; Based on the three-phase bridge arm voltage measurement values and the three-phase bridge arm voltage command values, and based on DC voltage-frequency-phase control, obtaining the voltage phase of the static var generator input to the power grid; Based on the reactive power command value, the AC voltage amplitude command value, the output reactive power measurement value, and the AC voltage amplitude measurement value, through reactive-voltage droop control, obtaining the direct-axis AC voltage amplitude of the static var generator; Through a voltage loop and an AC current loop, based on the direct-axis voltage measurement value, the quadrature-axis voltage measurement value, the voltage phase input to the power grid, the output AC current measurement value, and the direct-axis AC voltage amplitude, obtaining three-phase modulation voltages; Based on the three-phase modulation voltages, obtaining switch tube control signals, and based on the switch tube control signals, completing the grid-forming control of the static var generator.

2. The network forming control method of the static var generator without a super capacitor according to claim 1, characterized in that, The obtaining the voltage phase of the static var generator input to the power grid based on the three-phase bridge arm voltage measurement values and the three-phase bridge arm voltage command values, and based on DC voltage-frequency-phase control, includes: Taking the average value of the three-phase bridge arm voltage measurement values to obtain an average measured voltage value; Taking the difference between the average measured voltage value and the three-phase bridge arm voltage command values as the DC voltage average deviation value; Applying the DC voltage average deviation value multiplied by the DC voltage droop coefficient to obtain a proportionally amplified DC voltage average deviation value; Multiplying the proportionally amplified DC voltage average deviation value by the reciprocal of the virtual inertia parameter simulating the rotor inertia to obtain a first intermediate quantity, passing the proportionally amplified DC voltage average deviation value through a lag differential link to obtain a second intermediate quantity, and adding the first intermediate quantity and the second intermediate quantity to obtain the angular frequency change value of the static var generator input to the power grid; Adding the angular frequency change value to the rated angular frequency to obtain the angular frequency of the static var generator input to the power grid, and integrating the angular frequency to obtain the voltage phase of the static var generator input to the power grid.

3. The network forming control method of the static var generator without supercapacitor according to claim 1, characterized in that, The obtaining the direct-axis AC voltage amplitude of the static var generator through reactive-voltage droop control based on the reactive power command value, the AC voltage amplitude command value, the output reactive power measurement value, and the AC voltage amplitude measurement value, includes: Taking the difference between the reactive power command value and the output reactive power measurement value as the reactive power deviation value; Multiplying the reactive power deviation value by the reactive droop coefficient to obtain a reactive droop amount; Taking the difference between the AC voltage amplitude command value and the AC voltage amplitude measurement value at the point of common coupling as the AC voltage amplitude deviation value; Multiplying the AC voltage amplitude deviation value by the voltage droop coefficient to obtain a voltage droop amount; The difference between the reactive power droop and the voltage droop is passed through a proportional-integral controller to obtain the direct-axis AC voltage amplitude of the static var generator.

4. The network forming control method of the static var generator without super capacitor according to any one of claims 1 to 3, characterized in that, The three-phase modulation voltage is obtained through the voltage loop and the AC current loop according to the direct-axis voltage measurement value, the quadrature-axis voltage measurement value, the voltage phase input to the power grid, the output AC current measurement value, and the direct-axis AC voltage amplitude, including: The difference between the direct-axis AC voltage amplitude and the direct-axis voltage measurement value of the point of common coupling is passed through a proportional-integral controller to obtain the direct-axis current command. The difference between the quadrature-axis AC voltage amplitude (set to 0) and the quadrature-axis voltage measurement value of the point of common coupling is passed through a proportional-integral controller to obtain the quadrature-axis current command. The direct-axis current command and the quadrature-axis current command are passed through a circular current limiting link to obtain the limited direct-axis current command and quadrature-axis current command. Based on the limited quadrature-axis current command, direct-axis current command, and the voltage phase input to the power grid, a dq inverse transformation is performed to obtain the AC current command. The difference between the AC current command and the output AC current measurement value is passed through a quasi-proportional-resonant controller to obtain the three-phase modulation voltage.

5. The network-forming control method of the static var generator without a super capacitor according to claim 4, characterized in that, The step of passing the direct-axis current command and the quadrature-axis current command through a circular current limiting link to obtain the limited direct-axis current command and quadrature-axis current command includes: The limited quadrature-axis current command \(i\) is obtained according to the following formula qref and the direct-axis current command \(i\) dref : Among them, is the direct-axis current command, is the quadrature-axis current command, and I max is the maximum current command amplitude allowed by the circular current limiting link.

6. The network forming control method of the static var generator without a super capacitor according to claim 4, characterized in that, The transfer function expression of the quasi-proportional-resonant controller is: where k p is the proportionality coefficient of the quasi-proportional-resonant controller, k r is the resonant coefficient of the quasi-proportional-resonant controller, ω c is the cut-off frequency of the resonant link of the quasi-proportional-resonant controller, s is the differential operator, and ω is the angular frequency.

7. A grid-forming control system for a static var generator without a supercapacitor, characterized in that, Including: An acquisition device for acquiring the variables required for the control of the static var generator, where the variables required for the control include: three-phase bridge arm voltage measurement values, three-phase bridge arm voltage command values, reactive power command values, AC voltage amplitude command values, output reactive power measurement values, output AC current measurement values, AC voltage amplitude measurement values of the point of common coupling, direct-axis voltage measurement values, and quadrature-axis voltage measurement values. A first control device for obtaining the voltage phase input from the static var generator to the power grid based on DC voltage-frequency-phase control according to the three-phase bridge arm voltage measurement values and the three-phase bridge arm voltage command values. A second control device for obtaining the direct-axis AC voltage amplitude of the static var generator through reactive-voltage droop control according to the reactive power command value, the AC voltage amplitude command value, the output reactive power measurement value, and the AC voltage amplitude measurement value. A third control device for obtaining the three-phase modulation voltage through the voltage loop and the AC current loop according to the direct-axis voltage measurement value, the quadrature-axis voltage measurement value, the voltage phase input to the power grid, the output AC current measurement value, and the direct-axis AC voltage amplitude. A three-phase modulation device for obtaining the switch tube control signal according to the three-phase modulation voltage and completing the grid-forming control of the static var generator according to the switch tube control signal.

8. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the grid-forming control method of the static var generator without a super capacitor according to any one of claims 1 to 6.

9. A computer-readable storage medium having computer instructions stored thereon, characterized in that, When the instruction is executed by the processor, it implements the grid-forming control method of the static var generator without a super capacitor according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by a processor, the network formation control method of the static var generator without a super capacitor according to any one of claims 1 to 6 is implemented.

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