Method and device for controlling dc side voltage of network-forming SVG equipment and electronic equipment

Abstract

The application belongs to the technical field of grid-connected system control of network-structured SVG, and discloses a DC side voltage control method and device of network-structured SVG equipment and electronic equipment, to solve the problem that there is no control technology for the DC side voltage of the network-structured SVG in the prior art, and the stable control of the DC side voltage of the SVG cannot be realized. The application introduces the voltage deviation and the capacitor energy deviation into the internal frequency generation process by establishing a capacitor dynamic control equation that combines the DC voltage deviation and the DC capacitor energy deviation, and simultaneously introduces a damping and inertia link, that is, the inertia and damping coefficients are used to simulate the delay and damping characteristics of the actual synchronous generator. In this way, the DC voltage tracking can be realized through the foregoing deviation control, so as to ensure the stability of the DC side voltage. Meanwhile, the introduced damping and inertia coefficients can also ensure the stability of the generated internal frequency, so as to ensure the frequency support of the equipment to the power grid, and further improve the stability of the voltage control.

Description

Technical Field

[0001] This invention relates to the field of grid-connected SVG system control technology, specifically to a DC-side voltage control method, device, and electronic equipment for grid-connected SVG devices. Background Technology

[0002] With the increasing proportion of new energy power generation and the rapid expansion of modern cities, problems such as insufficient dynamic reactive power compensation and limited cross-sectional power are becoming increasingly prominent. Among them, power electronic converters play an increasingly important role as renewable energy interfaces. In large-scale new energy power plants, configuring highly controllable grid-type static var generators (SVG) and other equipment can significantly improve the voltage stability of the system, thereby ensuring stable system operation.

[0003] Currently, existing grid-connected equipment can be divided into two types according to the different DC-side inputs. One type has a constant voltage source on the DC side, such as energy storage converters, fixed-power flexible DC converter stations, and some photovoltaic and wind power converters. These devices can output active power to the grid, and their output voltage phase is determined by the active power control loop. However, based on the reactive power distribution requirements of new power systems, another type of reactive power compensation equipment does not have a constant voltage source on the DC side, such as static var generators with supercapacitors on the DC side. Therefore, new requirements are placed on the control of the converter's DC-side voltage. However, existing grid-connected control schemes mostly assume a constant DC capacitor voltage, using the active frequency to generate the internal potential phase angle through the controller, or directly adopting a grid-following control strategy. However, due to SVG... On the left side of the SVG, there is only a DC capacitor, whose output active power is 0. Furthermore, there is no power injected to the left of the DC capacitor from any power source; therefore, the active power output of the converter is also 0. Consequently, the aforementioned existing technology cannot generate the internal frequency required for SVG DC-side voltage control. Based on this, existing new energy equipment lacks control technology for the DC-side voltage of grid-connected SVGs, and cannot achieve stable control of the SVG DC-side voltage. At the same time, although some control schemes use PI control to stabilize the DC capacitor voltage, the control loop is relatively simple, with shortcomings such as poor stability and low flexibility. Therefore, based on the aforementioned shortcomings, it is urgent to provide a control method for the DC-side voltage of grid-connected SVG equipment to achieve stable control of the SVG DC-side voltage. Summary of the Invention

[0004] The technical problem to be solved by the present invention is the problem of grid-connected voltage control of grid-connected SVG. The purpose is to provide a method, device and electronic equipment for controlling the DC side voltage of grid-connected SVG equipment, which solves the problem that the traditional technology lacks control technology for the DC side voltage of grid-connected SVG and cannot achieve stable control of the DC side voltage of SVG.

[0005] This invention is achieved through the following technical solution:

[0006] Firstly, a method for controlling the DC-side voltage of a grid-type SVG device is provided, including:

[0007] Obtain the DC-side capacitor voltage, DC-side voltage reference value, and DC capacitor energy reference value of the grid-type SVG device;

[0008] Based on the DC-side capacitor voltage, DC-side voltage reference value, and DC capacitor energy reference value, a capacitor dynamic control equation that integrates DC voltage deviation and DC capacitor energy deviation is constructed.

[0009] Using the capacitor dynamic control equation, an internal frequency feedback control equation containing a tracking coefficient, an inertia coefficient, and a damping coefficient is constructed. The tracking coefficient is used to control the output deviation of the capacitor dynamic control equation, the inertia coefficient is used to control the delay of the actual synchronous generator corresponding to the grid-type SVG device, and the damping coefficient is used to control the damping deviation between the internal frequency output by the internal frequency feedback control equation and the reference frequency. The output deviation integrates the DC voltage deviation and the DC capacitor energy deviation.

[0010] Using the internal frequency feedback control equation, the internal frequency of the grid connection point is obtained. Based on the internal frequency and the pre-constructed reactive power control loop and voltage and current inner loop, a pulse width modulation signal for the grid-connected SVG device is generated so as to adjust the DC side voltage of the grid-connected SVG device based on the pulse width modulation signal.

[0011] Based on the above disclosure, this invention constructs a DC capacitor voltage-frequency loop for network-type SVG devices to generate the internal frequency required for DC-side voltage control of the SVG. Specifically, it first constructs a capacitor dynamic control equation that integrates DC voltage deviation and DC capacitor energy deviation; then, using the capacitor dynamic control equation, it establishes an internal frequency feedback control equation (equivalent to the control formula of the DC capacitor voltage-frequency loop) including tracking coefficient, inertia coefficient, and damping coefficient. The tracking coefficient is used to control the output deviation of the capacitor dynamic control equation (equivalent to tracking the DC voltage by controlling the voltage deviation and capacitor energy deviation, thus achieving...). (DC-side voltage stability) The inertia coefficient is used to control the delay of the actual synchronous generator corresponding to the grid-type SVG equipment, while the damping coefficient is used to control the damping deviation between the internal frequency output by the internal frequency feedback control equation and the reference frequency (equivalent to simulating the damping characteristics of the actual synchronous generator frequency); thus, this invention is equivalent to establishing an internal frequency construction equation containing inertia, damping, and DC voltage tracking; then, based on the aforementioned internal frequency feedback control equation, the internal frequency required for DC-side voltage control of the SVG equipment can be obtained; finally, by combining the pre-constructed reactive power control loop and voltage and current inner loop, stable control of the DC-side voltage of the grid-type SVG equipment can be achieved.

[0012] Through the above design, this invention introduces capacitor voltage deviation and capacitor energy deviation into the internal frequency generation process by establishing a capacitor dynamic control equation that integrates DC voltage deviation and DC capacitor energy deviation. Simultaneously, damping and inertia are introduced, using inertia and damping coefficients to simulate the delay and damping characteristics of an actual synchronous generator. Thus, by controlling the aforementioned voltage and capacitor energy deviations, DC voltage tracking can be achieved, ensuring DC-side voltage stability. Furthermore, the introduced damping and inertia coefficients ensure the stability of the generated internal frequency, guaranteeing the equipment's frequency support to the power grid and further improving voltage control stability. Therefore, this invention proposes a control technology for the DC-side voltage of grid-connected SVG equipment, achieving the goals of internal frequency construction and stable DC-side voltage control in grid-connected equipment. It fills the technical gap in DC-side voltage control for grid-connected SVG equipment, ensuring the stable operation of new energy grid-connected systems, and is therefore highly suitable for large-scale application and promotion.

[0013] In one possible design, based on the DC-side capacitor voltage, the DC-side voltage reference value, and the DC capacitor energy reference value, a capacitor dynamic control equation integrating the DC voltage deviation and the DC capacitor energy deviation is constructed, including:

[0014] Obtain the average DC capacitor voltage, peak value of DC capacitor voltage, and DC side capacitance of the network-type SVG device;

[0015] The DC capacitor energy of the grid-type SVG device is calculated based on the average DC capacitor voltage, the peak value of the DC capacitor voltage peak, and the DC side capacitance.

[0016] Calculate the DC voltage deviation between the DC side voltage reference value and the DC side capacitor voltage, and the DC capacitor energy deviation between the DC capacitor energy reference value and the DC capacitor energy.

[0017] Based on the DC voltage deviation and the DC capacitor energy deviation, the dynamic control equation of the capacitor is constructed.

[0018] In one possible design, the DC capacitor energy of the grid-type SVG device is calculated based on the average DC capacitor voltage, the peak value of the DC capacitor voltage, and the DC-side capacitance, including:

[0019] The energy of the DC capacitor is calculated according to the following formula (1);

[0020] (1)

[0021] In the above formula (1), P C C represents the energy of the DC capacitor. dc This refers to the DC-side capacitor. This represents the average voltage of the DC capacitor. This indicates the peak value of the DC capacitor voltage peak.

[0022] In one possible design, based on the DC voltage deviation and the DC capacitor energy deviation, the dynamic control equation for the capacitor is constructed, including:

[0023] The dynamic control equation for the capacitor is constructed according to the following formula (2);

[0024] (2)

[0025] In the above formula (2), ERR represents the dynamic control equation for the capacitor. G(s) represents the transfer function of the low-pass filter, K C This represents the proportionality coefficient. This indicates the energy deviation of the DC capacitor. This represents the DC voltage deviation, where, P represents the reference value of the DC capacitor energy. C This represents the energy of the DC capacitor. This represents the DC-side voltage reference value, and This represents the DC-side capacitor voltage.

[0026] In one possible design, using the capacitor dynamic control equations, an internal frequency feedback control equation is constructed that includes the tracking coefficient, inertia coefficient, and damping coefficient, including:

[0027] The internal frequency feedback control equation is constructed according to the following formula (3);

[0028] (3)

[0029] In the above formula (3), Indicates the internal frequency. The reference frequency is represented by ERR, which represents the dynamic control equation for the capacitor. The inertia coefficient, tracking coefficient, and damping coefficient are represented in that order, and s represents the complex frequency variable.

[0030] In one possible design, the inertia coefficient, the tracking coefficient, and the damping coefficient are determined in the following manner;

[0031] Determine the order of magnitude of the tracking coefficient, inertia coefficient, and damping coefficient, as well as the initial adjustment coefficient;

[0032] The initial inertia coefficient and the initial damping coefficient are calculated based on their respective orders of magnitude and the initial adjustment coefficient.

[0033] Substituting the initial inertia coefficient and initial damping coefficient into the internal frequency feedback control equation, the first control equation is obtained.

[0034] The tracking coefficients are obtained by using the first governing equation and based on the initial adjustment coefficients and order of magnitude of the tracking coefficients;

[0035] Substituting the tracking coefficient and the initial damping coefficient into the internal frequency feedback control equation, we obtain the second control equation;

[0036] The inertia coefficient is obtained by using the second governing equation and based on the initial adjustment coefficient and order of magnitude of the inertia coefficient;

[0037] Substituting the tracking coefficient and inertia coefficient into the internal frequency feedback control equation, we obtain the third control equation;

[0038] The damping coefficient is obtained by using the third governing equation and based on the initial adjustment coefficient and order of magnitude of the damping coefficient.

[0039] In one possible design, the tracking coefficients are optimized using the first governing equation and based on the initial adjustment coefficients and order of magnitude of the tracking coefficients, including:

[0040] Set the initial adjustment factor for the tracking coefficient to q, where q is a natural number;

[0041] Calculate the product of q and the order of magnitude of the tracking coefficient to obtain the initial tracking coefficient;

[0042] Substituting the initial tracking coefficients into the first control equation, we obtain the first adjustment control equation;

[0043] Using the first adjustment control equation, the reactive power control loop, and the voltage and current inner loop, the DC-side voltage of the grid-type SVG device is adjusted so that the peak voltage of the DC-side voltage of the grid-type SVG device after adjustment is obtained.

[0044] Determine whether the voltage peak value is less than or equal to the maximum voltage peak value;

[0045] If not, then q is decremented by 1, and the product of q and the tracking coefficient is recalculated until the voltage peak value is less than or equal to the maximum voltage peak value, at which point the tracking coefficient is obtained.

[0046] In one possible design, the inertia coefficient is optimized using the second governing equation and based on the initial adjustment coefficients and order of magnitude of the inertia coefficient, including:

[0047] The initial inertia coefficient is obtained by multiplying the initial adjustment factor of the inertia coefficient with the corresponding order of magnitude.

[0048] Substituting the initial inertia coefficient into the second control equation, we obtain the second adjustment control equation;

[0049] Using the second adjustment control equation, the reactive power control loop, and the voltage and current inner loop, the DC side voltage of the grid-type SVG device is adjusted so that the voltage adjustment time of the grid-type SVG device is obtained after adjustment. The voltage adjustment time is the time when the peak value of the DC side voltage of the grid-type SVG device first reaches the voltage threshold.

[0050] Determine whether the voltage adjustment time is between the minimum adjustment time and the maximum adjustment time;

[0051] If not, update the initial adjustment coefficient of the inertia coefficient to obtain a new adjustment coefficient. When the voltage adjustment time is less than the minimum adjustment time, decrease the initial adjustment coefficient of the inertia coefficient by one to obtain the new adjustment coefficient. When the voltage adjustment time is greater than the maximum adjustment time, increase the initial adjustment coefficient of the inertia coefficient by one to obtain the new adjustment coefficient.

[0052] The initial adjustment factor of the inertia coefficient is updated to the new adjustment factor, and the product of the initial adjustment factor of the inertia coefficient and the corresponding order of magnitude is recalculated until the voltage adjustment time is between the minimum adjustment time and the maximum adjustment time, and the inertia coefficient is obtained.

[0053] Secondly, a DC-side voltage control device for a grid-type SVG device is provided, comprising:

[0054] The acquisition unit is used to acquire the DC-side capacitor voltage, DC-side voltage reference value, and DC capacitor energy reference value of the grid-type SVG device.

[0055] The capacitor dynamic control unit is used to construct a capacitor dynamic control equation that integrates DC voltage deviation and DC capacitor energy deviation based on DC side capacitor voltage, DC side voltage reference value and DC capacitor energy reference value.

[0056] An internal frequency feedback control unit is used to construct an internal frequency feedback control equation that includes a tracking coefficient, an inertia coefficient, and a damping coefficient using a capacitor dynamic control equation. The tracking coefficient is used to control the output deviation of the capacitor dynamic control equation, the inertia coefficient is used to control the delay of the actual synchronous generator corresponding to the grid-type SVG device, and the damping coefficient is used to control the damping deviation between the internal frequency output by the internal frequency feedback control equation and the reference frequency. The output deviation incorporates the DC voltage deviation and the DC capacitor energy deviation.

[0057] The voltage control unit is used to derive the internal frequency of the grid connection point using the internal frequency feedback control equation, and to generate a pulse width modulation signal for the grid-connected SVG device based on the internal frequency and the pre-constructed reactive power control loop and voltage and current inner loop, so as to adjust the DC side voltage of the grid-connected SVG device based on the pulse width modulation signal.

[0058] Thirdly, another DC-side voltage control device for a network-type SVG device is provided. Taking the device as an electronic device as an example, it includes a memory, a processor, and a transceiver that are connected in sequence. The memory is used to store a computer program, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute the DC-side voltage control method for the network-type SVG device as described in the first aspect or any possible design of the first aspect.

[0059] Fourthly, a storage medium is provided, on which instructions are stored, which, when executed on a computer, perform a DC-side voltage control method for the network-type SVG device as described in the first aspect or any possible design of the first aspect.

[0060] Fifthly, a computer program product containing instructions is provided, which, when executed on a computer, causes the computer to perform a DC-side voltage control method for the network-type SVG device as described in the first aspect or any possible design of the first aspect.

[0061] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0062] This invention establishes a capacitor dynamic control equation that integrates DC voltage deviation and DC capacitor energy deviation, introducing these deviations into the internal frequency generation process. Simultaneously, damping and inertia are introduced, using inertia and damping coefficients to simulate the delay and damping characteristics of a real synchronous generator. Thus, by controlling the aforementioned voltage and capacitor energy deviations, DC voltage tracking can be achieved, ensuring DC-side voltage stability. Furthermore, the introduced damping and inertia coefficients guarantee the stability of the generated internal frequency, ensuring the equipment's frequency support to the grid and further improving voltage control stability. Therefore, this invention proposes a DC-side voltage control technology for grid-connected SVG equipment, achieving the goals of internal frequency construction and stable DC-side voltage control for grid-connected equipment. It fills the technological gap in DC-side voltage control for grid-connected SVG equipment, ensuring the stable operation of new energy grid-connected systems, and is therefore highly suitable for large-scale application and promotion. Attached Figure Description

[0063] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0064] Figure 1 A flowchart illustrating the steps of the DC-side voltage control method for a grid-type SVG device provided in an embodiment of the present invention;

[0065] Figure 2 This is a control structure diagram of the DC capacitor voltage-frequency loop provided in an embodiment of the present invention;

[0066] Figure 3 A flowchart of the algorithm for coefficient optimization in the internal frequency feedback control equation provided in an embodiment of the present invention;

[0067] Figure 4 This is a control structure diagram of a grid-connected SVG system provided in an embodiment of the present invention;

[0068] Figure 5 This is a control structure diagram of the voltage and current inner loop provided in an embodiment of the present invention;

[0069] Figure 6 The DC voltage waveform diagram under improved control provided in the embodiments of the present invention;

[0070] Figure 7 Frequency curve of PCC point under improved control provided in embodiments of the present invention;

[0071] Figure 8 The three-phase voltage and current waveform diagram of the PCC point under improved control provided in the embodiments of the present invention;

[0072] Figure 9 This is a schematic diagram of the DC-side voltage control device for a grid-type SVG device provided in an embodiment of the present invention;

[0073] Figure 10 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0074] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for explanation only and are not intended to limit the invention. It should be understood that although terms such as "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit, without departing from the scope of the exemplary embodiments of this invention.

[0075] Example: See Figure 1 As shown, the DC-side voltage control method for grid-connected SVG equipment provided in this embodiment establishes a capacitor dynamic control equation that integrates DC voltage deviation and DC capacitor energy deviation. This incorporates the capacitor voltage deviation and capacitor energy deviation into the internal frequency generation process, while simultaneously introducing damping and inertia elements. Specifically, inertia and damping coefficients are used to simulate the delay and damping characteristics of an actual synchronous generator. Thus, by controlling the aforementioned voltage and capacitor energy deviations, DC voltage tracking can be achieved, ensuring DC-side voltage stability. Furthermore, the introduced damping and inertia coefficients ensure the stability of the generated internal frequency, thereby guaranteeing the equipment's frequency support for the power grid and further improving... The stability of voltage control; thus, this method provides a direct voltage control method based on DC capacitor voltage-frequency loop for grid-connected SVG equipment, which realizes the purpose of frequency construction and DC-side voltage stability control within the grid-connected equipment, fills the technical gap in DC-side voltage control of grid-connected SVG equipment, and can ensure the stable operation of new energy grid-connected systems. Therefore, it is very suitable for large-scale application and promotion. For example, this method can be operated on the grid-connected control side, but is not limited to it. It is understood that the aforementioned execution subject does not constitute a limitation on the embodiments of this application. Accordingly, the operation steps of this method can be, but are not limited to, the steps S1 to S4 below.

[0076] S1. Obtain the DC-side capacitor voltage, DC-side voltage reference value, and DC capacitor energy reference value of the grid-type SVG device. In specific implementation, since there is only a DC capacitor on the left side of the SVG, its output active power is 0, and there is no power injected by a power source on the left side of the DC capacitor. Therefore, the converter output active power is 0. Based on this, the internal frequency of the SVG cannot be constructed using an active-frequency loop. Thus, in this embodiment, the internal frequency is generated by the DC capacitor voltage and the controller, that is, a DC capacitor voltage-frequency loop is established to generate the internal frequency required for the DC-side voltage control of the grid-type SVG device. Of course, the aforementioned DC-side voltage reference value and DC capacitor energy reference value are preset values.

[0077] Among them, see Figure 2 As shown, the DC capacitor voltage-frequency loop mainly includes a capacitor dynamic link (i.e., capacitor dynamic control link) and a frequency feedback loop (i.e., internal frequency feedback control link) containing inertia, damping, and DC tracking links. The two are cascaded to form a complete DC capacitor voltage-frequency loop. Optionally, the capacitor dynamic control link will be described in detail below, and the process can be, but is not limited to, the steps shown in step S2 below.

[0078] S2. Based on the DC-side capacitor voltage, DC-side voltage reference value, and DC capacitor energy reference value, a capacitor dynamic control equation integrating DC voltage deviation and DC capacitor energy deviation is constructed. In specific applications, since the periodic fluctuation of the DC-side capacitor voltage of the grid-type SVG device can generate power and exchange energy with the outside world, the capacitor dynamic control link constructed in this embodiment performs proportional control on the deviation between the DC capacitor energy and the reference value. Then, together with the deviation between the DC-side capacitor voltage and the reference value, it passes through a low-pass filter to filter out high-frequency harmonic components in the signal. Thus, by controlling the DC voltage deviation and the DC capacitor energy deviation, the stability of the control is ensured.

[0079] The process of constructing the control formula (i.e., the capacitor dynamic control equation) corresponding to the aforementioned capacitor dynamic control loop can be, but is not limited to, as shown in steps S21 to S24 below.

[0080] S21. Obtain the average DC capacitor voltage, the peak value of the DC capacitor voltage, and the DC side capacitance of the grid-type SVG device. In this embodiment, the voltage and capacitance of the grid-type SVG device can be directly sampled to obtain the aforementioned three parameters. Then, the DC capacitor energy of the grid-type SVG device can be calculated using the aforementioned three parameters, as shown in step S22 below.

[0081] S22. Calculate the DC capacitor energy of the grid-type SVG device based on the average voltage of the DC capacitor, the peak value of the DC capacitor voltage peak, and the DC side capacitance; in specific applications, for example, but not limited to, the following formula (1) can be used to calculate the DC capacitor energy.

[0082] (1)

[0083] In the above formula (1), P C C represents the energy of the DC capacitor. dc This refers to the DC-side capacitor. This represents the average voltage of the DC capacitor. This indicates the peak value of the DC capacitor voltage peak.

[0084] Thus, after calculating the DC capacitor energy based on the aforementioned formula (1), the voltage deviation and capacitor energy deviation can be calculated by combining the DC capacitor energy reference value, the DC side capacitor voltage and the DC side voltage reference value, as shown in step S23 below.

[0085] S23. Calculate the DC voltage deviation between the DC side voltage reference value and the DC side capacitor voltage, and the DC capacitor energy deviation between the DC capacitor energy reference value and the DC capacitor energy. In this embodiment, after obtaining the DC voltage deviation and DC capacitor energy deviation based on step S23, the capacitor dynamic control equation can be constructed based on the aforementioned two deviations, as shown in step S24 below.

[0086] S24. Based on the DC voltage deviation and the DC capacitor energy deviation, construct the capacitor dynamic control equation; in specific implementation, for example, but not limited to, construct the capacitor dynamic control equation according to the following formula (2).

[0087] (2)

[0088] In the above formula (2), ERR represents the dynamic control equation for the capacitor. G(s) represents the transfer function of the low-pass filter, K C This represents the proportionality coefficient. This indicates the energy deviation of the DC capacitor. This represents the DC voltage deviation, where, P represents the reference value of the DC capacitor energy. C This represents the energy of the DC capacitor. This represents the DC-side voltage reference value, and This represents the DC-side capacitor voltage.

[0089] Therefore, after constructing the capacitor dynamic control equation through the aforementioned steps S21 to S24, the output of the capacitor dynamic control equation (i.e., the output deviation that integrates the DC voltage deviation and the DC capacitor energy deviation) can be used as the input of the internal frequency feedback control loop. In this way, DC voltage tracking can be performed by controlling the DC voltage deviation and the DC capacitor energy deviation, thereby achieving the stability of the DC side voltage. At the same time, this embodiment also introduces inertia and damping coefficients into the internal frequency feedback control loop to simulate the delay and frequency damping characteristics of the actual synchronous generator. The construction process of the internal frequency feedback control loop can be, but is not limited to, as shown in step S3 below.

[0090] S3. Using the capacitor dynamic control equation, an internal frequency feedback control equation is constructed, which includes a tracking coefficient, an inertia coefficient, and a damping coefficient. The tracking coefficient is used to control the output deviation of the capacitor dynamic control equation, the inertia coefficient is used to control the delay of the actual synchronous generator corresponding to the grid-type SVG device, and the damping coefficient is used to control the damping deviation between the internal frequency output by the internal frequency feedback control equation and the reference frequency. The output deviation incorporates the DC voltage deviation and the DC capacitor energy deviation.

[0091] In practical applications, this embodiment constructs an internal frequency control scheme that includes inertia, damping, and DC voltage tracking components; wherein, see [link to relevant documentation]. Figure 2 As shown, the output deviation of the capacitor dynamic control equation is input to the internal frequency feedback control loop. In this loop, the output deviation of the aforementioned capacitor dynamic control loop achieves DC-side voltage stabilization through a DC tracking loop, i.e., by utilizing the tracking coefficient K. q This is used to control the output deviation, thereby achieving DC voltage tracking and ensuring DC side voltage stability.

[0092] Secondly, since new energy power generation equipment, such as wind power and photovoltaic power generation, has low rotational inertia, this can negatively impact the stability of the power system. Therefore, in new energy power generation systems, virtual synchronous machine (VSG) technology is typically used to enhance the frequency stability of the system. VSG technology is a grid-connected control strategy that simulates the operating characteristics of actual synchronous generators (such as traditional thermal power plants), increasing the equivalent inertia of the grid and thus improving the stability of the power system. Therefore, to adapt to the grid-connected control strategy of new energy power generation systems, this embodiment also sets an inertia coefficient K before internal frequency generation. J The control incorporates an inertia element to simulate the delay and suppression dynamics of a real synchronous generator. Finally, to generate a stable internal frequency, thereby ensuring frequency support for the power grid and improving voltage control stability, this embodiment also designs a damping element for the deviation between the frequency feedback and the reference frequency, which is controlled by a damping coefficient K. DTherefore, this stage is equivalent to simulating the damping characteristics of the actual synchronous generator frequency.

[0093] Thus, based on the foregoing description, the control equation (i.e., the internal frequency feedback control equation) corresponding to the internal frequency control loop containing inertia, damping and DC voltage tracking constructed in this embodiment can be, but is not limited to, the following formula (3).

[0094] (3)

[0095] In the above formula (3), Indicates the internal frequency. The reference frequency is represented by ERR, which represents the dynamic control equation for the capacitor. The inertia coefficient, tracking coefficient, and damping coefficient are represented sequentially, and s represents the complex frequency variable. Here, s is essentially an operation indicator (unlike traditional variables), used to indicate different operations, such as: This means that the expression will go through an integration step (i.e., an integration operation will be performed), and This means that after integration, the expression will pass through an inertia stage with arbitrary coefficients.

[0096] Thus, the aforementioned formula (3) is essentially the overall control equation of the aforementioned DC capacitor voltage-frequency loop; and as can be seen from the aforementioned formula (3), this embodiment can achieve the function of both DC side voltage control and building the internal frequency of the grid-type equipment by increasing the deviation control of voltage and capacitor energy, as well as damping and inertia control, and can provide a stable internal frequency for the grid-type SVG equipment, thereby ensuring the frequency support of the equipment to the power grid and ensuring the stability of voltage control.

[0097] After completing the construction of the overall control equations for the DC capacitor voltage-frequency loop, it is necessary to determine the tracking coefficient, damping coefficient, and inertia coefficient that meet the system control requirements. The following disclosure of one of the optimization processes for the aforementioned tracking coefficient, damping coefficient, and inertia coefficient can be, but is not limited to, as shown in steps S31 to S38 below.

[0098] S31. Determine the order of magnitude of the tracking coefficient, inertia coefficient and damping coefficient, as well as the initial adjustment coefficient. In this embodiment, the influence of each coefficient on the control dynamics is obtained according to the aforementioned formula (3), thereby determining the adjustment range of each coefficient's set value. Specifically, the aforementioned formula (3) can be transformed into the following formula (4).

[0099] (4)

[0100] In the above formula (4), All represent control coefficients; among them, Reflecting the gain, to ensure dynamic tracking, it exhibits a large order of magnitude, and the coefficients... The inertia time constant is inversely proportional to the rate of change of frequency, and to ensure a fast system response, it is on a smaller order of magnitude; while the coefficient coefficient The extension of is expressed as a smaller order of magnitude.

[0101] Therefore, by comparing the expression on the left side of the aforementioned formula (3) with formula (4), a coefficient correspondence is essentially generated (see both the numerator and denominator of the two formulas simultaneously), such as K in formula (3). q Corresponding to A1 in formula (4), i.e., K q Equals A1; while K J The position, and Correspondingly, therefore, K J equal Of course, the correspondence between the other control coefficients and the aforementioned tracking coefficient, damping coefficient and inertia coefficient can be directly derived from formula (4) and formula (3), and will not be elaborated here.

[0102] Thus, through the aforementioned coefficient correspondence, an order of magnitude function can be established to determine the order of magnitude of each coefficient adjustment; for example, the tracking coefficient can be used to illustrate this, and the following formula (5) can be used to determine the order of magnitude of the tracking coefficient.

[0103] (5)

[0104] In the above formula (5), This represents the order of magnitude of the inertia coefficient; where, Indicates the order of magnitude indicator function;

[0105] .

[0106] In this embodiment, an example is provided based on the aforementioned example, where x takes the value A1 and k takes the value K. q At that time, it can be seen from the aforementioned coefficient correspondence that A1 equals K. q ,therefore, The value is 1. Similarly, when x takes the value A2, there is no corresponding relationship between the two. It is 0; of course, when x takes different values, The calculation process is the same, and will not be repeated here.

[0107] Thus, using the aforementioned formula (5), the tracking coefficient, inertia coefficient, and order of magnitude of the tracking coefficient can be determined. In this embodiment, the calculated values ​​are... Therefore, the tracking coefficient is on the order of 10. 2 The inertia coefficient is on the order of 10.-4 The damping coefficient is on the order of 10. 0 .

[0108] In addition, the initial adjustment coefficients of the aforementioned tracking coefficient, inertia coefficient and damping coefficient can be set according to actual use. In this embodiment, they are set to 9, 5 and 5 respectively.

[0109] After obtaining the order of magnitude of the tracking coefficient, inertia coefficient, and damping coefficient, as well as the initial adjustment coefficient, the initial inertia coefficient and initial damping coefficient can be calculated, as shown in step S32 below.

[0110] S32. Calculate the initial inertia coefficient and initial damping coefficient based on their respective orders of magnitude and the initial adjustment coefficient. In practice, multiply the order of magnitude of the inertia coefficient by its initial adjustment coefficient to obtain the initial inertia coefficient. Similarly, multiply the order of magnitude of the damping coefficient by its initial adjustment coefficient to obtain the initial damping coefficient. After obtaining the initial damping coefficient and initial inertia coefficient, they can be fixed, and the tracking coefficient can be used as a variable to optimize the tracking coefficient. The process is shown in steps S33 and S34 below.

[0111] S33. Substituting the initial inertia coefficient and initial damping coefficient into the internal frequency feedback control equation yields the first control equation; in practical applications, this is equivalent to substituting K... J， K D Replace them with the initial inertia coefficient and initial damping coefficient, and then, K q As variables, the optimal tracking coefficients are obtained by iterating through them one by one; the optimization process of the tracking coefficients is shown in step S34 below.

[0112] S34. Using the first control equation and based on the initial adjustment coefficient and order of magnitude of the tracking coefficient, the tracking coefficient is optimized to obtain the tracking coefficient. In specific implementation, this is equivalent to fixing the inertia coefficient and damping coefficient, and then continuously adjusting the initial adjustment coefficient of the tracking coefficient to obtain different initial tracking coefficients. Then, these different initial tracking coefficients are substituted into the first control equation, and the optimal tracking coefficient is obtained by setting boundary conditions for the peak voltage after the DC-side voltage of the grid-type SVG device stabilizes. See [link to relevant documentation]. Figure 3 As shown, the aforementioned process may be, but is not limited to, the steps S34a to S34f described below.

[0113] S34a. Set the initial adjustment coefficient of the tracking coefficient to q, where q is a natural number; in this embodiment, q can be set to 9, for example, but is not limited to 9; thus, it is equivalent to adjusting the initial adjustment coefficient of the tracking coefficient starting from 9, and the process is as shown in step S34b below.

[0114] S34b. Calculate the product of q and the order of magnitude of the tracking coefficient to obtain the initial tracking coefficient; after obtaining an initial tracking coefficient, it can be substituted into the first control equation so that the control of the networked SVG device can be performed based on the first control equation with the initial tracking coefficient substituted. The process is shown in step S34c below.

[0115] S34c. Substitute the initial tracking coefficient into the first control equation to obtain the first adjustment control equation. In this embodiment, after substituting the initial tracking coefficient into the first control equation, the three coefficients inside are known quantities. Therefore, the obtained first adjustment control equation can be used to control the DC side voltage of the grid-type SVG device, so as to determine whether the initial tracking coefficient substituted this time is the optimal value based on the voltage peak value after the DC side voltage of the grid-type SVG device stabilizes. The process of using the first adjustment control equation to control the voltage of the grid-type SVG device is as shown in step S34d below.

[0116] S34d. Using the first adjustment control equation, the reactive power control loop, and the voltage-current inner loop, the DC-side voltage of the grid-connected SVG device is adjusted to obtain the peak voltage of the grid-connected SVG device after the DC-side voltage stabilizes. In this embodiment, the first adjustment control equation is used to output the internal frequency of the grid connection point. Then, the reactive power control loop uses the three-phase voltage and three-phase current at the grid common coupling point (grid connection point) to calculate the reactive power. Then, an internal potential is generated and output to the voltage-current inner loop through a proportional-integral controller. Next, the voltage-current inner loop generates a reference voltage based on the internal potential and the collected three-phase current at the common coupling point. Finally, after pulse width modulation, the SVG is controlled to obtain the peak voltage of its corresponding DC-side voltage after stabilization. In this embodiment, the aforementioned SVG control process is described in detail in step S4 below, and whether the DC-side voltage is stable can be identified by the waveform. That is, when there are no noise and spikes in the waveform, the voltage can be determined to be stable.

[0117] Thus, after obtaining the peak voltage of the DC side of the grid-type SVG device after it has stabilized, it can be compared with the set boundary conditions to determine whether it meets the boundary conditions; the judgment process is as shown in step S34e below.

[0118] S34e. Determine whether the voltage peak value is less than or equal to the maximum voltage peak value; in this embodiment, the maximum voltage peak value... The specific settings can be configured according to different grid connection systems, and no specific limitations are made here; among them, when the voltage peak value... If the voltage exceeds the maximum peak value, it indicates that the voltage control does not meet the boundary conditions. Therefore, the tracking coefficient needs to be adjusted, and the process is shown in step S34f below.

[0119] S34f. If not, then decrement q by 1 and recalculate the product of q and the order of magnitude of the tracking coefficient until the voltage peak is less than or equal to the maximum voltage peak, thus obtaining the tracking coefficient. In this embodiment, after decrementing q by 1, multiplying it by its corresponding order of magnitude yields a new initial tracking coefficient. Substituting this back into the first control equation yields a new internal frequency. Voltage control based on this new internal frequency then yields a new voltage peak. Based on this, a further judgment is made to determine whether voltage control after substituting the new initial tracking coefficient satisfies the boundary conditions. Based on the judgment result, q is adjusted again until the aforementioned boundary conditions are met, thus obtaining the optimal initial adjustment coefficient for the tracking coefficient. Finally, multiplying this coefficient by the order of magnitude of the tracking coefficient yields the optimal tracking coefficient. At this point, the optimization of the tracking coefficient is complete. The aforementioned optimization process can be found in [reference needed]. Figure 3 As shown.

[0120] Thus, by going through the aforementioned steps S34a to S34f, the tracking coefficient can be optimized. Then, the tracking coefficient and damping coefficient can be fixed, and the inertia coefficient can be used as the parameter to be optimized to optimize the inertia coefficient. The process is shown in steps S35 and S36 below.

[0121] S35. Substitute the tracking coefficient and the initial damping coefficient into the internal frequency feedback control equation to obtain the second control equation. In this embodiment, the tracking coefficient has been optimized in the aforementioned step S34. Then, the tracking coefficient and the initial damping coefficient are substituted into the internal frequency feedback control equation. At this time, the unknown quantity in the equation is the inertia coefficient. Thus, the inertia coefficient can be optimized in the same way as described above, as shown in step S36 below.

[0122] S36. Using the second control equation and based on the initial adjustment coefficient and order of magnitude of the inertia coefficient, the inertia coefficient is optimized to obtain the inertia coefficient; in specific implementation, the optimization process of the inertia coefficient is the same as that of the tracking coefficient, only the boundary conditions are different; wherein, for the inertia coefficient, this embodiment uses the voltage adjustment time t s The inertia coefficient is optimized using the boundary conditions; optionally, but not limited to, the following steps S36a to S36f can be used to optimize the damping coefficient based on the voltage adjustment time.

[0123] S36a. Calculate the product of the initial adjustment factor of the inertia coefficient and the corresponding order of magnitude to obtain the initial inertia coefficient.

[0124] After obtaining an initial inertia coefficient, it is substituted into the second control equation. At this time, the three coefficients in the second control equation are all known values. Therefore, the voltage control of the grid-type SVG device can be carried out based on this, as shown in steps S36b and S36c below.

[0125] S36b. Substitute the initial inertia coefficient into the second control equation to obtain the second adjustment control equation.

[0126] S36c. Using the second adjustment control equation, the reactive power control loop, and the voltage and current inner loop, the DC-side voltage of the grid-type SVG device is adjusted so that the voltage adjustment time of the grid-type SVG device is obtained after adjustment, wherein the voltage adjustment time is the time when the peak value of the DC-side voltage of the grid-type SVG device first reaches the voltage threshold.

[0127] In this embodiment, the process of adjusting the DC side voltage of the grid-type SVG device using the second adjustment control equation can be referred to in the aforementioned step S34d, and will not be repeated here; at the same time, the voltage threshold can be, but is not limited to, 0.5 times the target voltage, and the target voltage is the voltage peak obtained in the last time when optimizing the tracking coefficient, that is, the voltage peak obtained when controlling the grid-type SVG device with the optimal tracking coefficient.

[0128] Thus, based on the second adjustment control equation and combined with the reactive power control loop and the voltage and current inner loop, the DC side voltage of the grid-type SVG equipment is controlled, and the corresponding voltage regulation time is obtained. Then, it can be determined whether it is between the minimum regulation time and the maximum condition time, so as to choose whether to continue optimization based on the judgment result. The judgment process is as shown in step S36d below.

[0129] S36d. Determine whether the voltage adjustment time is between the minimum adjustment time and the maximum adjustment time; in this embodiment, see... Figure 3 As shown, if ( If the minimum adjustment time and the maximum adjustment time are represented sequentially, then the initial inertia coefficient in step S36a can be directly used as the optimal inertia coefficient. Otherwise, it is necessary to update the initial adjustment coefficient corresponding to the inertia coefficient. The update process is shown in step S36e below.

[0130] S36e. If not, update the initial adjustment coefficient of the inertia coefficient to obtain a new adjustment coefficient. Specifically, when the voltage adjustment time is less than the minimum adjustment time, decrement the initial adjustment coefficient of the inertia coefficient by one to obtain the new adjustment coefficient; when the voltage adjustment time is greater than the maximum adjustment time, increment the initial adjustment coefficient of the inertia coefficient by one to obtain the new adjustment coefficient. In specific applications, if... If J is decremented by 1 (J represents the initial adjustment factor for the inertia coefficient), then if If J is incremented by 1, the new adjustment coefficient is multiplied by the corresponding order of magnitude to obtain a new initial inertia coefficient. Then, using the same principle, the second adjustment control equation is obtained, and the voltage control of the grid-type SVG device is performed to obtain a new voltage regulation time. In this way, the new voltage regulation time is judged again, and J is adjusted again based on the judgment result. Based on this, the optimization steps are repeated continuously using the aforementioned principle to obtain the optimal inertia coefficient.

[0131] Optionally, the specific iterative optimization process is shown in step S36f below.

[0132] S36f. Update the initial adjustment coefficient of the inertia coefficient to the new adjustment coefficient, and recalculate the product of the initial adjustment coefficient of the inertia coefficient and the corresponding order of magnitude until the voltage adjustment time is between the minimum adjustment time and the maximum adjustment time, and obtain the inertia coefficient.

[0133] Therefore, through the aforementioned steps S36a to S36f, the inertia coefficient can be optimized. After optimizing the tracking coefficient and the inertia coefficient, only the damping coefficient remains as an unknown in the entire internal frequency feedback control equation. Therefore, by directly substituting the two into the internal frequency feedback control equation, the third control equation can be obtained. Then, based on the third control equation, and in the same manner as described above, the damping coefficient can be optimized, as shown in steps S37 and S38 below.

[0134] S37. Substitute the tracking coefficient and inertia coefficient into the internal frequency feedback control equation to obtain the third control equation.

[0135] S38. Using the third governing equation and based on the initial adjustment coefficient and order of magnitude of the damping coefficient, the damping coefficient is optimized to obtain the damping coefficient. In this embodiment, the optimization process of the damping coefficient is the same as that of the inertia coefficient, only the boundary conditions are different. Specifically, for the damping coefficient, this embodiment sets its boundary condition to the voltage cycle time T. s Wherein, the voltage cycle time is the time of one cycle of the voltage waveform corresponding to the DC side voltage of the grid-type SVG device.

[0136] For details, see Figure 3 As shown, the optimization process is as follows: (1) Calculate the product of the initial adjustment coefficient of the damping coefficient and the corresponding order of magnitude to obtain the initial damping coefficient; (2) Substitute the initial damping coefficient into the third control equation to obtain the third adjustment control equation; (3) Use the third adjustment control equation, the reactive power control loop and the voltage and current inner loop to adjust the DC side voltage of the grid-type SVG device so as to obtain the voltage cycle time of the grid-type SVG device after adjustment, wherein the voltage cycle time is the time of one cycle of the voltage waveform corresponding to the DC side voltage of the grid-type SVG device; (4) Determine whether the voltage cycle time is between the minimum cycle time and the maximum cycle time (i.e., whether it satisfies the condition). ,in, (5) If not, update the initial adjustment coefficient of the damping coefficient to obtain the updated adjustment coefficient. When the voltage cycle time is less than the minimum cycle time, decrease the initial adjustment coefficient D of the damping coefficient by one to obtain the updated coefficient. When the voltage cycle time is greater than the maximum cycle time, increase the initial adjustment coefficient D of the damping coefficient by one to obtain the updated coefficient. (6) Replace the initial adjustment coefficient of the damping coefficient with the updated adjustment coefficient and recalculate the product of the initial adjustment coefficient of the damping coefficient and the corresponding order of magnitude until the voltage cycle time is between the minimum cycle time and the maximum cycle time to obtain the damping coefficient.

[0137] In this embodiment, the aforementioned minimum cycle time and maximum cycle time, as well as the minimum adjustment time and maximum adjustment time, can be specifically set according to actual use, and are not specifically limited here.

[0138] Thus, through the aforementioned steps S31 to S38, the tracking coefficient, damping coefficient, and inertia coefficient that meet the actual working conditions can be output; then, by substituting them into the aforementioned formula (3), the final internal frequency feedback control equation can be obtained; finally, based on the internal frequency feedback control equation, the internal frequency of the grid connection point can be obtained, and based on this, the voltage control of the grid-connected SVG equipment can be completed; wherein, the voltage control process is as shown in step S4 below.

[0139] S4. Using the internal frequency feedback control equation, the internal frequency of the grid connection point is obtained. Based on the internal frequency and the pre-constructed reactive power control loop and voltage and current inner loop, a pulse width modulation signal for the grid-type SVG device is generated so as to adjust the DC side voltage of the grid-type SVG device based on the pulse width modulation signal.

[0140] In this embodiment, the actual DC-side capacitor voltage and DC capacitor energy of the grid-type SVG device are substituted into the aforementioned formula (3) to obtain the internal frequency of the grid connection point; then, the pulse width modulation signal of the grid-type SVG device can be generated by combining the reactive power control loop and the voltage and current inner loop, thereby realizing the control of the DC-side voltage of the grid-type SVG device.

[0141] Specifically, the control structure diagram of the publicly disclosed grid-connected SVG system can be found in [reference needed]. Figure 4 As shown, the main circuit consists of a network-type SVG device and a filter, i.e. Figure 3 V in dc C is the DC-side capacitor voltage. dc This is a DC-side supercapacitor; Vg and Ig are the voltage and current at the point of common coupling (PCC), respectively; Vs is the space voltage phasor of the power grid; Rs and Ls represent the equivalent resistance and inductance of the power grid lines, respectively; and the control circuit includes a DC capacitor voltage-frequency loop, a reactive power control loop, and a voltage-current inner loop. dc_ref Q is the reference value for the DC side voltage. ref V0 is the reference value for reactive power, and V0 is the reference value for internal electromotive force. and These are the frequency reference value (i.e., the reference frequency) and the generated internal frequency, respectively.

[0142] Furthermore, the DC capacitor voltage-frequency loop, based on the input SVG DC capacitor side voltage and its reference value, uses a controller to keep the DC capacitor side voltage at the reference value and autonomously generates the internal frequency. The controller in the DC capacitor voltage-frequency loop integrates the aforementioned capacitor dynamic control equation and internal frequency feedback control equation. The process of generating the internal frequency can be found in steps S1 to S4.

[0143] The reactive power control loop collects the three-phase voltage and three-phase current at the grid's common coupling point to calculate the reactive power Q. e To achieve zero steady-state error tracking, a PI (proportional-integral) controller is used to control the reactive power at the reference value and autonomously generate an internal potential to serve as the d-axis voltage reference V for the voltage-current loop. d_ref This process can be represented by the following formula:

[0144] (6)

[0145] In formula (6), V d_ref Q represents the internal electric potential. ref Q eLet V0 represent the reference value of reactive power and reactive power, respectively, and let PI(s) represent the transfer function of the PI controller. ,in, These are the proportional coefficient and the integral coefficient.

[0146] Thus, after the internal potential is output through the aforementioned reactive power control loop, it can be input into the voltage and current inner loop.

[0147] In this embodiment, the control structure diagram of the voltage and current inner loop is shown below. Figure 5 As shown (which includes an inner voltage loop and an inner current loop), where C f ,L f These are the filter capacitor and filter inductor used for decoupling, respectively; simultaneously, the three-phase voltage and three-phase current at the common coupling point of the power grid are transformed using dq transformation to obtain the d-axis voltage and current, respectively. V d_ref V represents the internal electromotive force output by the reactive power control loop. q_ref This is the q-axis voltage reference value, which is obtained from the active power. Since the active power output of the SVG is 0, therefore, V... q_ref Set it to 0; thus, after inputting the aforementioned d-axis voltage and current, internal potential, and q-axis voltage reference values ​​into the voltage and current inner loop, the reference voltage e can be output. d e q Finally, after dq transformation and pulse width modulation, a pulse width modulation signal can be generated, thereby realizing the control of the DC side voltage of the grid-type SVG device.

[0148] in addition, Figure 5 The "+" sign in the circle indicates a positive input, while the "-" sign indicates a negative input, meaning a subtraction is performed; simultaneously, V d After input, and with internal frequency and C f Multiply and with V q_ref The outputs of the PI controllers in the branch are summed to input the current into the inner current loop; of course, the rest of the calculation process will not be described in detail.

[0149] Furthermore, the specific implementation methods and application effects of the control method provided in this embodiment are given below:

[0150] In practical applications, MATLAB / Simulink is used to simulate the above model. The DC-side supercapacitor is set to 8F, the given DC voltage is 700V, and the per-unit voltage and power base values ​​are 380V and 170kW / kVar, respectively. The voltage, current, and power values ​​input to each stage are then per-unit processed to obtain per-unit values. The control loop constructed according to steps S2 and S3 is then simulated. Simultaneously, after coefficient optimization, the inertia coefficient in this embodiment is set to 5e.4 The damping coefficient is 2, and the DC tracking coefficient is 500. This embodiment provides an improved waveform diagram of the DC voltage under control, as shown below. Figure 6 As shown, from Figure 6 As can be seen, the DC voltage can converge quickly and stabilize around the given value with an error of less than 0.2%, achieving DC tracking. Furthermore, after the equipment starts up, the PCC point frequency quickly reaches the grid frequency of 50Hz and is controlled to fluctuate around it, demonstrating good frequency support. Figure 7 As shown; furthermore, the three-phase current waveform at point PCC is good, and the three-phase voltage is stable at 311V, indicating the grid's ability to provide voltage support to the power grid, such as... Figure 8 As shown, this demonstrates that the improved control strategy proposed in this embodiment has a better voltage control effect.

[0151] Therefore, through the DC-side voltage control method for grid-connected SVG equipment described in detail in steps S1 to S4 above, this invention proposes a control technology for the DC-side voltage of grid-connected SVG equipment. This technology achieves the purpose of frequency construction and stable DC-side voltage control within the grid-connected equipment, filling the technical gap in DC-side voltage control for grid-connected SVG equipment and ensuring the stable operation of new energy grid-connected systems. Furthermore, compared with general direct voltage control methods, this invention improves the damping and inertia aspects by adding feedback loop analog damping and inertia, and strengthening the control and stability of the constructed frequency. Thus, adjusting the control parameters can change the magnitude of the virtual inertia and damping, thereby ensuring stable DC-side operation by controlling the DC voltage. Moreover, the designed frequency feedback loop is more effective under conditions with higher frequency support requirements, facilitating practical application and ensuring the stable operation of new energy systems. Therefore, this invention is highly suitable for large-scale application and promotion.

[0152] like Figure 9 As shown, the second aspect of this embodiment provides a hardware device for implementing the DC-side voltage control method for a grid-type SVG device described in the first aspect of the embodiment, comprising:

[0153] The acquisition unit is used to acquire the DC-side capacitor voltage, DC-side voltage reference value, and DC capacitor energy reference value of the network-type SVG device.

[0154] The capacitor dynamic control unit is used to construct a capacitor dynamic control equation that integrates DC voltage deviation and DC capacitor energy deviation based on DC-side capacitor voltage, DC-side voltage reference value, and DC capacitor energy reference value.

[0155] An internal frequency feedback control unit is used to construct an internal frequency feedback control equation that includes a tracking coefficient, an inertia coefficient, and a damping coefficient using a capacitor dynamic control equation. The tracking coefficient is used to control the output deviation of the capacitor dynamic control equation, the inertia coefficient is used to control the delay of the actual synchronous generator corresponding to the grid-type SVG device, and the damping coefficient is used to control the damping deviation between the internal frequency output by the internal frequency feedback control equation and the reference frequency. The output deviation incorporates the DC voltage deviation and the DC capacitor energy deviation.

[0156] The voltage control unit is used to derive the internal frequency of the grid connection point using the internal frequency feedback control equation, and to generate a pulse width modulation signal for the grid-connected SVG device based on the internal frequency and the pre-constructed reactive power control loop and voltage and current inner loop, so as to adjust the DC side voltage of the grid-connected SVG device based on the pulse width modulation signal.

[0157] The working process, working details and technical effects of the device provided in this embodiment can be found in the first aspect of the embodiment, and will not be repeated here.

[0158] like Figure 10 As shown, the third aspect of this embodiment provides another DC-side voltage control device for a network-type SVG device. Taking the device as an electronic device as an example, it includes: a memory, a processor, and a transceiver that are connected in sequence. The memory is used to store a computer program, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute the DC-side voltage control method for the network-type SVG device as described in the first aspect of the embodiment.

[0159] For specific examples, the memory may include, but is not limited to, random access memory (RAM), read-only memory (ROM), flash memory, first-in-first-out (FIFO) memory, and / or first-in-last-out (FILO) memory, etc.; specifically, the processor may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor may be implemented using at least one hardware form of DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), PLA (Programmable Logic Array). The processor may also include a main processor and a coprocessor. The main processor, also known as the CPU (Central Processing Unit), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state.

[0160] In some embodiments, the processor may integrate a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the screen. For example, the processor may not be limited to microprocessors of the STM32F105 series, RISC microprocessors, x86 architecture processors, or processors with integrated embedded neural network processors (NPUs). The transceiver may be, but is not limited to, a Wi-Fi transceiver, a Bluetooth transceiver, a General Packet Radio Service (GPRS) transceiver, a ZigBee (a low-power LAN protocol based on the IEEE 802.15.4 standard) transceiver, a 3G transceiver, a 4G transceiver, and / or a 5G transceiver. Furthermore, the device may also include, but is not limited to, a power module, a display screen, and other necessary components.

[0161] The working process, working details and technical effects of the electronic device provided in this embodiment can be found in the first aspect of the embodiment, and will not be repeated here.

[0162] The fourth aspect of this embodiment provides a storage medium that stores instructions for a DC-side voltage control method for a network-type SVG device as described in the first aspect of the embodiment. That is, the storage medium stores instructions that, when executed on a computer, perform the DC-side voltage control method for the network-type SVG device as described in the first aspect of the embodiment.

[0163] The storage medium refers to a carrier for storing data, which may include, but is not limited to, floppy disks, optical disks, hard disks, flash memory, USB flash drives, and / or memory sticks. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.

[0164] The working process, working details and technical effects of the storage medium provided in this embodiment can be found in the first aspect of the embodiment, and will not be repeated here.

[0165] The fifth aspect of this embodiment provides a computer program product containing instructions that, when executed on a computer, cause the computer to perform the DC-side voltage control method for a network-type SVG device as described in the first aspect of this embodiment, wherein the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.

[0166] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A direct current side voltage control method of a network configuration type SVG device, characterized by, The method comprises the following steps: obtaining the DC side capacitor voltage, the DC side voltage reference value and the DC capacitor energy reference value of the grid-connected SVG device; based on the DC side capacitor voltage, the DC side voltage reference value and the DC capacitor energy reference value, a capacitor dynamic control equation is constructed, which fuses the DC voltage deviation and the DC capacitor energy deviation; using the capacitor dynamic control equation, an inner frequency feedback control equation is constructed, which contains a tracking coefficient, an inertia coefficient and a damping coefficient, wherein the tracking coefficient is used to control the output deviation of the capacitor dynamic control equation, the inertia coefficient is used to control the delay of the actual synchronous generator corresponding to the grid-connected SVG device, and the damping coefficient is used to control the damping deviation between the inner frequency output by the inner frequency feedback control equation and the reference frequency, and the output deviation fuses the DC voltage deviation and the DC capacitor energy deviation; using the inner frequency feedback control equation, the inner frequency of the grid-connected point is obtained, and based on the inner frequency and the pre-constructed reactive power control loop and voltage current inner loop, a pulse width modulation signal of the grid-connected SVG device is generated, so as to adjust the DC side voltage of the grid-connected SVG device based on the pulse width modulation signal.

2. The method of claim 1, wherein, Based on the DC side capacitor voltage, the DC side voltage reference value and the DC capacitor energy reference value, a capacitor dynamic control equation is constructed, which fuses the DC voltage deviation and the DC capacitor energy deviation, comprising: obtaining the DC capacitor average voltage, the peak value of the DC capacitor voltage peak and the DC side capacitor of the grid-connected SVG device; According to the DC capacitor average voltage, the peak value of the DC capacitor voltage peak and the DC side capacitor, the DC capacitor energy of the grid-connected SVG device is calculated; The DC voltage deviation between the DC side voltage reference value and the DC side capacitor voltage, and the DC capacitor energy deviation between the DC capacitor energy reference value and the DC capacitor energy are calculated; According to the DC voltage deviation and the DC capacitor energy deviation, the capacitor dynamic control equation is constructed.

3. The method of claim 2, wherein, According to the DC capacitor average voltage, the peak value of the DC capacitor voltage peak and the DC side capacitor, the DC capacitor energy of the grid-connected SVG device is calculated, comprising: According to the following formula (1), the DC capacitor energy is calculated; （1） In the above equation (1), P C represents the direct current capacitor energy, C dc represents the direct current side capacitor, represents the direct current capacitor average voltage, represents the peak value of the direct current capacitor voltage peak.

4. The method of claim 2, wherein, According to the DC voltage deviation and the DC capacitor energy deviation, the capacitor dynamic control equation is constructed, comprising: According to the following formula (2), the capacitor dynamic control equation is constructed; （2） In the above equation (2), ERR represents the capacitor dynamic control equation, G(s) represents a transfer function of a low-pass filter, K C represents a proportional coefficient, represents the DC capacitor energy deviation, represents the DC voltage deviation, wherein, represents the DC capacitor energy reference value, P C represents the DC capacitor energy, represents the DC side voltage reference value, and represents the DC side capacitor voltage.

5. The method of claim 1, wherein, The inertia coefficient, the tracking coefficient and the damping coefficient are determined in the following way: The order of magnitude and the initial adjustment coefficient of the tracking coefficient, the inertia coefficient and the damping coefficient are determined; According to the order of magnitude and the initial adjustment coefficient of the inertia coefficient and the damping coefficient, the initial inertia coefficient and the initial damping coefficient are calculated respectively; The initial inertia coefficient and the initial damping coefficient are substituted into the inner frequency feedback control equation to obtain a first control equation; The tracking coefficient is obtained by optimizing the first control equation based on the initial adjustment coefficient and the order of magnitude of the tracking coefficient; The tracking coefficient and the initial damping coefficient are substituted into the inner frequency feedback control equation to obtain a second control equation; The inertia coefficient is obtained by optimization using the second control equation and based on an initial adjustment coefficient and an order of magnitude of the inertia coefficient; The third control equation is obtained by substituting the tracking coefficient and the inertia coefficient into the inner frequency feedback control equation; The damping coefficient is obtained by optimization using the third control equation and based on an initial adjustment coefficient and an order of magnitude of the damping coefficient.

6. The method of claim 5, wherein, The tracking coefficient is obtained by optimization using the first control equation and based on an initial adjustment coefficient and an order of magnitude of the tracking coefficient, including: setting the initial adjustment coefficient of the tracking coefficient as q, wherein q is a natural number; calculating the product of q and the order of magnitude of the tracking coefficient to obtain an initial tracking coefficient; substituting the initial tracking coefficient into the first control equation to obtain a first adjustment control equation; adjusting the DC side voltage of the grid-connected SVG device using the first adjustment control equation, the reactive power control loop and the voltage and current inner loop, so that after the adjustment, a voltage peak value of the DC side voltage of the grid-connected SVG device after stabilization is obtained; determining whether the voltage peak value is less than or equal to the maximum voltage peak value; if not, then reducing q by 1, and recalculating the product of q and the order of magnitude of the tracking coefficient until the voltage peak value is less than or equal to the maximum voltage peak value, thereby obtaining the tracking coefficient.

7. The method of claim 5, wherein, The inertia coefficient is obtained by optimization using the second control equation and based on an initial adjustment coefficient and an order of magnitude of the inertia coefficient, including: calculating the product of the initial adjustment coefficient of the inertia coefficient and the corresponding order of magnitude to obtain an initial inertia coefficient; substituting the initial inertia coefficient into the second control equation to obtain a second adjustment control equation; adjusting the DC side voltage of the grid-connected SVG device using the second adjustment control equation, the reactive power control loop and the voltage and current inner loop, so that after the adjustment, a voltage adjustment time of the grid-connected SVG device is obtained, wherein the voltage adjustment time is the time when the peak value of the DC side voltage of the grid-connected SVG device reaches a voltage threshold value for the first time; determining whether the voltage adjustment time is between a minimum adjustment time and a maximum adjustment time; if not, then updating the initial adjustment coefficient of the inertia coefficient to obtain a new adjustment coefficient, wherein when the voltage adjustment time is less than the minimum adjustment time, the initial adjustment coefficient of the inertia coefficient is reduced by 1 to obtain the new adjustment coefficient, and when the voltage adjustment time is greater than the maximum adjustment time, the initial adjustment coefficient of the inertia coefficient is increased by 1 to obtain the new adjustment coefficient; updating the initial adjustment coefficient of the inertia coefficient to the new adjustment coefficient, and recalculating the product of the initial adjustment coefficient of the inertia coefficient and the corresponding order of magnitude until the voltage adjustment time is between the minimum adjustment time and the maximum adjustment time, thereby obtaining the inertia coefficient.

8. A DC side voltage control device of a network configuration type SVG device, characterized by, including: an acquisition unit configured to acquire a DC side capacitor voltage, a DC side voltage reference value and a DC capacitor energy reference value of the grid-connected SVG device; a capacitor dynamic control unit configured to construct a capacitor dynamic control equation that fuses a DC voltage deviation and a DC capacitor energy deviation based on the DC side capacitor voltage, the DC side voltage reference value and the DC capacitor energy reference value; The inner frequency feedback control unit is configured to construct an inner frequency feedback control equation containing a tracking coefficient, an inertia coefficient and a damping coefficient by using the capacitance dynamic control equation, wherein the tracking coefficient is used to control the output deviation of the capacitance dynamic control equation, the inertia coefficient is used to control the delay of the actual synchronous generator corresponding to the grid-connected SVG device, and the damping coefficient is used to control the damping deviation between the inner frequency and the reference frequency output by the inner frequency feedback control equation, and the output deviation fuses the DC voltage deviation and the DC capacitance energy deviation. The voltage control unit is configured to obtain the inner frequency of the grid-connected point by using the inner frequency feedback control equation, generate the pulse width modulation signal of the grid-connected SVG device based on the inner frequency and the pre-constructed reactive power control loop and voltage current inner loop, and adjust the DC side voltage of the grid-connected SVG device based on the pulse width modulation signal.

9. An electronic device, comprising: The method comprises the following steps: The memory, the processor and the transceiver are sequentially connected in communication, the memory is configured to store a computer program, the transceiver is configured to transmit and receive messages, and the processor is configured to read the computer program and execute the DC side voltage control method of the grid-connected SVG device according to any one of claims 1 to 7.

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