Direct-current voltage synchronous control oscillation suppression method, system and device based on transient dynamic energy dissipation and medium

Abstract

The invention provides a direct-current voltage synchronous control oscillation suppression method, system, equipment and medium based on transient dynamic energy dissipation, and belongs to the technical field of direct-current voltage synchronous control. A direct-current voltage synchronous control converter is equivalent to a synchronous machine model, a power angle dynamic equation based on a power grid angular velocity is established, and a damping coefficient is defined; adjusting a damping coefficient based on a differential relationship of the DC voltage deviation to control an energy dissipation rate; by adjusting the proportionality coefficient and the high-pass cut-off frequency, the voltage-angular velocity phase characteristic meets the oscillation suppression requirement, and angular velocity and voltage deviation reverse offset is achieved; a damping coefficient and compensation loop parameters are dynamically adjusted in real time according to DC voltage fluctuation and frequency deviation, an adaptive matching relation is established in combination with equivalent rotational inertia, and a phase compensation effect is maintained to suppress oscillation amplitude. According to the method, an oscillation mechanism is analyzed, and transient kinetic energy and transient potential energy are defined. Low-frequency oscillation is effectively suppressed, and the dynamic stability of the system is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of DC voltage synchronous control, and in particular relates to a method, system, device and medium for suppressing oscillation of DC voltage synchronous control based on transient kinetic energy dissipation. Background Art

[0002] With the increasing penetration of high-proportion renewable energy and power electronics into power systems, the overall system strength is weakening, posing a significant challenge to the voltage support capabilities of renewable energy generators. Traditional grid-connected converter architectures, which rely on phase-locked loops (PLLs) to passively track grid phases, suffer from inherent stability flaws. Research has shown that when connected to a weak grid, the cross-coupling between the PLL and the converter's current loop control can induce system oscillations and instability.

[0003] To overcome this technical bottleneck, grid-based control strategies have become a research focus, simulating the characteristics of synchronous generators to gain inertial response capabilities. By incorporating inertial response characteristics similar to synchronous generators, renewable energy units can achieve autonomous grid support capabilities in scenarios with a high renewable energy penetration and high power electronics. Typical grid-based control strategies include droop control, virtual synchronous generator control, and DC voltage synchronization control. However, droop control and virtual synchronous generator control are difficult to apply to wind turbines that must maintain a constant DC voltage operating constraint.

[0004] The dynamic characteristics of the DC bus voltage essentially reflect the active power balance of the DC-side capacitors. Based on this, power-based synchronization mechanisms can be extended to the field of DC voltage regulation, forming DC voltage synchronous control (also known as DC voltage synchronous control). Existing literature has reported various DC voltage synchronous control implementation schemes, each with unique control variables and topologies. Despite the increasing diversity of DC voltage synchronous control methods, there is still a lack of systematic comparative evaluation of their synchronization stability under small disturbances. Furthermore, when input power suddenly changes or grid conditions change, rapid output adjustments are required to maintain system stability. However, existing control algorithms often fail to accurately coordinate changes in key parameters such as DC voltage and angular velocity, resulting in slow system dynamic response, large overshoot, and long transition times. This hinders the system's ability to respond promptly to rapidly changing power demands, reducing overall system efficiency and power quality. Summary of the Invention

[0005] The present invention provides a DC voltage synchronous control oscillation suppression method based on transient kinetic energy dissipation, and proposes an improved control strategy with the dissipation of transient kinetic energy as the core, which effectively suppresses system oscillation problems and improves the dynamic stability of the system.

[0006] Methods include: Step S101: Equivalently modeling the DC voltage synchronous control converter as a synchronous machine, defining the input power, grid-connected power, and equivalent moment of inertia of the synchronous machine model, and establishing a power angle dynamic equation based on the grid angular velocity. The power angle is composed of the electrical angle difference between the converter and the grid, and the angular velocity dynamics is generated by adjusting the DC voltage deviation through a control coefficient. Step S102: decomposing the oscillation energy into transient kinetic energy related to the equivalent moment of inertia and transient potential energy related to the power angle offset, wherein the transient potential energy is calculated by integrating the power difference with the power angle; Step S103: defining a damping coefficient, and using a closed-loop control loop to exponentially decay transient energy over time, and adjusting the damping coefficient based on the differential relationship of the DC voltage deviation to control the energy dissipation rate; Step S104: Adding a compensation channel in series with a proportional link and a high-pass filter in the control loop, and adjusting the proportional coefficient and the high-pass cutoff frequency so that the voltage-angular velocity phase characteristic meets the oscillation suppression requirement, thereby achieving reverse cancellation of the angular velocity and voltage deviations; Step S105: dynamically adjusting the damping coefficient and compensation loop parameters in real time according to the DC voltage fluctuation and frequency deviation, establishing an adaptive matching relationship in combination with the equivalent moment of inertia, maintaining the phase compensation effect to suppress the oscillation amplitude.

[0007] It should be further explained that the equation group of the synchronous machine model in step S101 is:

[0008] Where, P M 、 P e They are the synchronous machine input motive power and synchronous machine output electromagnetic power respectively; θ m 、 θ g are the angular displacements of the prime mover and the grid, respectively; ω m 、 ω g are the angular velocities of the synchronous machine rotor and the grid, respectively; Express x The differential of J is the moment of inertia of the prime mover; U Modulate the voltage amplitude for the grid-side converter; E is the grid voltage amplitude; X is the reactance between the grid-side converter and the grid synchronous generator; defines the power angle θ s = θ m - θ g .

[0009] It should be further explained that, in step S102, the oscillation energy is decomposed into transient kinetic energy and transient potential energy; Among them, the transient kinetic energy is half of the product of the equivalent moment of inertia and the square of the transient component of angular velocity; The transient potential energy is calculated by integrating the transient component of the power angle on the power-power angle characteristic curve. When the power angle θs deviates from the steady-state value, the potential energy increases linearly with the integral value of the power difference over the power angle.

[0010] It should be further explained that the grid angular velocity ω g As the angular velocity of the system reference coordinate system, when the system is in a steady state, the transient potential energy is 0. θ s = is the zero point of system potential energy; transient kinetic energy Expressed as: ; The temporary potential energy is:

[0011] Transient energy of synchronous machine grid-connected system is the sum of transient kinetic energy and transient potential energy, that is: .

[0012] It should be further explained that step S103 specifically includes: introducing a damping coefficient into the equivalent synchronous machine model, multiplying the damping power term by the transient component of the angular velocity and superimposing the resultant product into the angular velocity dynamic equation; designing a control loop so that the time derivative of the transient energy is equal to the product of the negative virtual damping term and the square of the transient component of the angular velocity, thereby ensuring that the transient energy decays exponentially with time, and deriving the differential relationship between the damping power term and the DC voltage deviation, thereby adjusting the energy dissipation rate by the damping coefficient.

[0013] It should be further explained that step S104 specifically includes: setting a forward compensation channel in the control loop, adopting a series structure of a proportional link and a high-pass filter to replace the differential link; setting the proportional coefficient kp and the high-pass cutoff frequency a so that the compensation loop is equivalent to a virtual damping control structure in the frequency domain characteristics, and by adjusting the proportional coefficient kp and the cutoff frequency a of the high-pass filter, the phase characteristics of the voltage-angular velocity transfer function meet the oscillation suppression requirements, thereby achieving reverse offset of the angular velocity change trend and the voltage deviation under input power disturbance.

[0014] It should be further explained that step S105 specifically includes: dynamically adjusting the matching relationship between the damping coefficient and the proportional coefficient kp according to the real-time detection value of the DC bus voltage fluctuation amplitude and the grid frequency deviation; establishing a functional relationship between the parameter adjustment factor and the equivalent moment of inertia to ensure the consistency of the transient energy dissipation rate under different working conditions; and adjusting the proportional coefficient kp and the cutoff frequency a of the high-pass filter through an adaptive algorithm to maintain the phase compensation effect of the compensation loop and achieve suppression of the oscillation amplitude.

[0015] The present application also provides a DC voltage synchronous control oscillation suppression system based on transient kinetic energy dissipation, the system comprising: The model equivalence and establishment module is used to equate the DC voltage synchronous control converter to a synchronous machine model, define the input power, grid-connected power, and equivalent moment of inertia of the synchronous machine model, and establish the power angle dynamic equation based on the grid angular velocity. The power angle is composed of the electrical angle difference between the converter and the grid, and the angular velocity dynamics is generated by adjusting the DC voltage deviation through the control coefficient. Energy decomposition calculation module, used to decompose the oscillation energy into transient kinetic energy related to the equivalent moment of inertia and transient potential energy related to the power angle offset. The transient potential energy is calculated by integrating the power difference with the power angle. The damping control and energy dissipation module is used to define the damping coefficient, make the transient energy decay exponentially over time through closed-loop control, and adjust the damping coefficient based on the differential relationship of the DC voltage deviation to control the energy dissipation rate; The compensation channel setting module is used to add a compensation channel in series with a proportional link and a high-pass filter in the control loop. By adjusting the proportional coefficient and high-pass cutoff frequency, the voltage-angular velocity phase characteristic meets the oscillation suppression requirements and achieves the reverse offset of angular velocity and voltage deviations. The parameter adaptive adjustment module is used to dynamically adjust the damping coefficient and compensation loop parameters in real time according to the DC voltage fluctuation and frequency deviation, establish an adaptive matching relationship based on the equivalent moment of inertia, maintain the phase compensation effect and suppress the oscillation amplitude.

[0016] According to another embodiment of the present application, an electronic device is provided, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the method for suppressing oscillations of DC voltage synchronous control based on transient kinetic energy dissipation when executing the program.

[0017] According to another embodiment of the present application, a storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the DC voltage synchronous control oscillation suppression method based on transient kinetic energy dissipation are implemented.

[0018] It can be seen from the above technical solutions that the present invention has the following advantages: This invention provides a method for suppressing oscillations in DC voltage synchronous control based on transient kinetic energy dissipation. In step S101, a DC voltage synchronous control converter is modeled as a synchronous machine. In step S103, a damping coefficient is introduced to construct a damped power term, and a control loop is designed to exponentially decay transient energy over time. Damping dissipates transient energy, accelerating the system's recovery from an oscillating state to a steady state, effectively suppressing oscillations and improving system stability. This method allows the system to rapidly damp oscillations and maintain stable operation in the face of factors such as power fluctuations and grid disturbances.

[0019] Step S102 decomposes the oscillation energy into transient kinetic energy and transient potential energy, clarifying the relationship between energy changes and system parameters. Step S104 adjusts the phase characteristics of the voltage-angular velocity transfer function by setting a proportional-high-pass filter compensation channel. This achieves a counter-offset between the angular velocity change trend and the voltage deviation under input power disturbances, allowing for rapid adjustment of the system output. This improves the system's dynamic response speed and reduces transition time and overshoot.

[0020] In step S104, a proportional link and a high-pass filter are connected in series to replace the differential link. The high-pass filter is used to extract the high-frequency component of the signal, and the amplitude is adjusted in combination with the proportional link. This is equivalent to a virtual damping control structure in the frequency domain characteristics, avoiding the practical application difficulties of the differential link.

[0021] Step S105 monitors the DC bus voltage fluctuation amplitude and grid frequency deviation in real time, establishes a functional relationship between the parameter adjustment factor and the equivalent moment of inertia, and dynamically adjusts the damping coefficient, proportionality factor kp, and high-pass filter cutoff frequency a through an adaptive algorithm, enabling the system to automatically optimize control parameters based on operating conditions. This ensures the system maintains excellent oscillation suppression and stable operation under conditions ranging from grid frequency fluctuations, DC voltage changes, and load variations, thereby enhancing system robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for the description. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 The flowchart of the DC voltage synchronous control oscillation suppression method based on transient kinetic energy dissipation is shown in FIG. Figure 2 This is a schematic diagram of the synchronous machine equivalent DC voltage synchronous control small signal; Figure 3 This is a small signal diagram of the capacitor's forward charging. Figure 4 It is a small signal diagram of transient kinetic energy suppression strategy; Figure 5 It is a small signal diagram of transient kinetic energy suppression strategy; Figure 6 It is a dynamic diagram of high-pass filter feedback value; Figure 7 is Δ ω d Schematic diagram of the changing dynamics; Figure 8 It is the overall control schematic diagram; Figure 9 It is the transient energy diagram of the transient kinetic energy suppression strategy; Figure 10 This is the input power step grid-connected active power simulation diagram; Figure 11 This is the input power step DC voltage simulation diagram; Figure 12 This is the input power step output frequency simulation diagram; Figure 13 This is the simulation diagram of grid-connected phase voltage with input power step; Figure 14 This is the simulation diagram of grid-connected line current with input power step; Figure 15 Schematic diagram of an electronic device. DETAILED DESCRIPTION

[0024] The following describes in detail the method for suppressing oscillations of a DC voltage synchronously controlled system based on transient kinetic energy dissipation, as described herein. Specific details, such as specific system structures and techniques, are provided for illustrative purposes, not for limitation, to facilitate a thorough understanding of the embodiments of the present application. However, it should be apparent to those skilled in the art that the present application may also be implemented in other embodiments without these specific details.

[0025] It should be understood that when used in this specification, the term "comprising" indicates the presence of the described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their collections. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.

[0026] The phrases "one embodiment" or "some embodiments" described in this application mean that the specific features, structures, or characteristics described in the embodiment are included in one or more embodiments of the application. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in other embodiments," etc. that appear in different places in this application do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized.

[0027] In embodiments of the present invention, computer program code for performing the operations of the present disclosure may be written in one or more programming languages, or a combination thereof, including but not limited to object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or power server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (exemplarily via the Internet using an Internet service provider).

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] See also Figure 1 FIG. 1 is a flow chart of a method for suppressing oscillations of a DC voltage synchronous control based on transient kinetic energy dissipation in a specific embodiment. The method includes: Step S101: Equivalently model the DC voltage synchronous control converter as a synchronous machine model, define the input power, grid-connected power and equivalent moment of inertia of the synchronous machine model, and establish a power angle dynamic equation based on the grid angular velocity. The power angle is composed of the electrical angle difference between the converter and the grid, and the angular velocity dynamics is generated by adjusting the DC voltage deviation through the control coefficient.

[0030] In some embodiments, a DC voltage synchronous control converter is modeled as a synchronous machine, clarifying the converter's front-end input power and the converter's grid-connected power. The equivalent moment of inertia of the DC bus capacitor is defined as the ratio of the square of the DC voltage to the grid's angular velocity. This definition establishes a relationship between DC-side electrical parameters and mechanical inertia. Using the grid's angular velocity as a reference, a dynamic equation for the power angle is constructed. The power angle is the difference between the converter's output electrical angle and the grid's electrical angle, reflecting the phase relationship between the converter and the grid.

[0031] Based on synchronous machine theory, this embodiment uses equivalent modeling to transform the electrical characteristics of a DC voltage synchronous control converter into mechanical-electrical coupling characteristics similar to those of a synchronous machine. Using the grid as a reference, changes in the power angle reflect system stability. The dynamic relationship between DC voltage deviation and angular velocity enables the system to adjust the output angle based on DC-side power changes, maintaining system stability.

[0032] In some specific embodiments, the equations of the synchronous machine model are:

[0033] Where, P M 、 P e They are the synchronous machine input motive power and synchronous machine output electromagnetic power respectively; θ m 、 θ g are the angular displacements of the prime mover and the grid, respectively; ω m 、 ω g are the angular velocities of the synchronous machine rotor and the grid, respectively; Express x The differential of J is the moment of inertia of the prime mover; U Modulate the voltage amplitude for the grid-side converter; E is the grid voltage amplitude; X is the reactance between the grid-side converter and the grid synchronous generator; defines the power angle θ s = θ m - θ g .

[0034] Step S102: decomposing the oscillation energy into transient kinetic energy related to the equivalent moment of inertia and transient potential energy related to the power angle offset. The transient potential energy is calculated by integrating the power difference with the power angle.

[0035] This embodiment meticulously decomposes the system's oscillation energy into transient kinetic energy and transient potential energy. Transient kinetic energy is calculated as half the product of the equivalent moment of inertia and the square of the transient component of angular velocity, reflecting the energy stored in the system due to changes in angular velocity during dynamic processes. Transient potential energy is calculated by integrating the transient component of the power angle over the power-power angle characteristic curve. When the power angle deviates from the steady-state value, the system power is unbalanced, and potential energy increases linearly with the integral of the power difference over the power angle, reflecting the energy stored in the system due to phase shift.

[0036] As can be seen, this embodiment categorizes energy changes during system oscillations. Transient kinetic energy is related to angular velocity, while transient potential energy is related to power angle. The mutual conversion of the two reflects the dynamic process of the system. By decomposing and calculating energy, the intensity and energy distribution of the system oscillation can be quantified.

[0037] For this embodiment, the transient kinetic energy The moment of inertia J and the transient component of angular velocity Δω d Calculated, that is: =1 / 2(JΔω d 2 ).

[0038] Temporal potential energy E p The transient component Δθ of the power angle is measured by the power difference ΔP s Points calculation: , when Δθ s When is small, it is approximately a linear relationship.

[0039] Step S103: defining a damping coefficient, making the transient energy decay exponentially over time through closed-loop control, and adjusting the damping coefficient based on the differential relationship of the DC voltage deviation to control the energy dissipation rate.

[0040] This embodiment introduces a damping coefficient into the equivalent synchronous machine model, constructs a damping power term, multiplies it by the transient component of angular velocity, and then adds it to the angular velocity dynamic equation. Through control loop design, the time derivative of the transient energy is equal to the product of the negative virtual damping term and the square of the transient component of angular velocity, thus ensuring that the transient energy decays exponentially over time. At the same time, a differential relationship between the damping power term and the DC voltage deviation is derived. By adjusting the damping coefficient, the energy dissipation rate can be precisely controlled, accelerating the system's recovery from an oscillating state to a steady state. The relationship between the damping coefficient and the DC voltage deviation enables the system to dynamically adjust the speed of energy dissipation according to actual operating conditions.

[0041] Optionally, a damping power term D·Δω is introduced into the angular velocity dynamic equation d, the differential relationship between damping power and DC voltage deviation is obtained by derivation: .

[0042] Step S104: Add a compensation channel in series with a proportional link and a high-pass filter in the control loop, and adjust the proportional coefficient and high-pass cutoff frequency so that the voltage-angular velocity phase characteristic meets the oscillation suppression requirement, thereby achieving reverse cancellation of the angular velocity and voltage deviations.

[0043] This embodiment incorporates a forward compensation channel within the control loop, employing a structure combining a proportional link and a high-pass filter in series to replace the difficult-to-implement differential link. By carefully setting the proportional coefficient and high-pass cutoff frequency, the compensation loop achieves frequency-domain characteristics equivalent to a virtual damping control structure. Adjusting the proportional coefficient kp and the high-pass filter's cutoff frequency a optimizes the phase characteristics of the voltage-angular velocity transfer function to meet oscillation suppression requirements. Ultimately, through appropriate parameter configuration, the compensation channel achieves the same effect as virtual damping control, altering the system's phase relationship and causing angular velocity and voltage deviations to mutually suppress each other, ultimately achieving oscillation suppression.

[0044] It should be noted that a compensation channel with a proportional coefficient kp connected in series with the cutoff frequency a of the high-pass filter is added to the control loop, and its transfer function is: Adjust kp and a to make the compensation channel equivalent to the differential link in the oscillation frequency band of 10~100Hz, and modify the phase characteristics of the voltage-angular velocity loop to make Δω d Changes in the opposite direction to ΔVdc.

[0045] Step S105: dynamically adjusting the damping coefficient and compensation loop parameters in real time according to the DC voltage fluctuation and frequency deviation, establishing an adaptive matching relationship in combination with the equivalent moment of inertia, maintaining the phase compensation effect to suppress the oscillation amplitude.

[0046] This embodiment detects the DC bus voltage fluctuation amplitude and grid frequency deviation in real time, and dynamically adjusts the matching relationship between the damping coefficient and the proportional coefficient kp based on the detected values. A functional relationship between the parameter adjustment factor and the equivalent moment of inertia is established to ensure that the transient energy dissipation rate remains consistent under different operating conditions. An adaptive algorithm continuously adjusts the proportional coefficient kp and the high-pass filter's cutoff frequency a to maintain the phase compensation effect of the compensation loop, enabling the system to adapt to various complex operating environments, improving the system's adaptability and robustness, effectively suppressing oscillations, and enhancing system reliability and stability.

[0047] On the basis of the above embodiments, in order to further improve the stability of the DC voltage synchronous control oscillation suppression method based on transient kinetic energy dissipation provided in the above embodiments, the following is a more specific implementation method. In this embodiment, a transient component is defined, and the DC voltage synchronous control converter is regarded as a synchronous machine connected to an infinite power grid.

[0048] At this time, the equations of the synchronous machine model are:

[0049] Where, P M 、 P e They are the synchronous machine input motive power and synchronous machine output electromagnetic power respectively; θ m 、 θ g are the angular displacements of the prime mover and the grid, respectively; ω m 、 ω g are the angular velocities of the synchronous machine rotor and the grid, respectively; Express x The differential of J is the moment of inertia of the prime mover; U Modulate the voltage amplitude for the grid-side converter; E is the grid voltage amplitude; X is the reactance between the grid-side converter and the grid synchronous generator; damping is not considered. Define the power angle θ s = θ m - θ g . ω g It remains unchanged at a constant value of 100πrad / s.

[0050] During the oscillation dynamic process, the phase angle and angular velocity of the system are composed of two parts: steady-state value and transient value. The steady-state value refers to the value of the phase angle and angular velocity when the system input remains unchanged and a sufficiently long time has passed to reach a steady state. If the steady-state value changes, it means that the system is transitioning from one steady state to another. In this process, transient values ​​of oscillation attenuation will appear. If express x The steady-state value of Δ x express x The transient value of , then: (1) In this embodiment, the grid angular velocity ω gAs the angular velocity of the system reference coordinate system, it is stipulated that when the system is in a steady state, the transient potential energy is 0, that is, θ s = is the zero point of the system potential energy.

[0051] At this time, the transient kinetic energy It can be expressed as: (2) The definition of potential energy can be compared to that of a spring system. The potential energy expression of a spring system is E p It can be written as: (3) where Δ x is a spring type variable, k is the elastic coefficient, and there exists: (4) in, P is the power exerted by the spring on the object, V is the velocity of the object under force.

[0052] For synchronous machine grid-connected systems, there are: (5) consider θ s Generally small, it can be simplified to: (6) Corresponding to formula (4), we can get: (7) Therefore, the potential energy of the synchronous machine grid-connected system can be written as: (8) Because of taking θ s = θ_ s is the zero point of the system potential energy, so the transient potential energy of the synchronous machine system can be written as: (9) Combining formula (3) and formula (10), the transient energy of the synchronous machine grid-connected system is defined as is the sum of transient kinetic energy and transient potential energy, that is: (10) The same analysis is performed on a DC voltage synchronous control converter connected to an infinite power grid. The equation for this model is: (11) in, C is the DC bus capacitance;V dc is the DC bus voltage; P m Input power to the front stage of the converter; P g is the grid-connected power of the converter; k dc is the DC voltage synchronization control coefficient; ω d Output angular frequency instruction for DC voltage synchronous control; θ d To synchronously control the output electrical angle of DC voltage, θ s = θ d - θ g .

[0053] This embodiment corresponds to the DC voltage synchronous control grid-connected system transient energy E ' It can be expressed as: (12) Through the above analysis and definition, the DC voltage synchronous control oscillation is described as a process of mutual conversion between transient kinetic energy and transient potential energy. The transient energy is the sum of the two and is used to measure the intensity of the system oscillation.

[0054] For the synchronous machine of this embodiment, the system has its own physical damping, while the grid-type converter adopts the control structure for simulation. In order to achieve the same resistance effect in the DC voltage synchronous control, the synchronous machine and DC voltage synchronous control need to be analyzed and matched respectively. The small signal block diagram is shown as follows: Figure 2 As shown, Figure 2 This is the synchronous machine equivalent DC voltage synchronous control small signal diagram, Figure 2 (a) is a schematic diagram of a small signal of a synchronous machine. Figure 2 (b) is a schematic diagram of the small signal of synchronous machine matching control.

[0055] The DC voltage synchronous control of this embodiment performs transient energy analysis: (13) D is the damping coefficient; ω n is the rated angular velocity of the synchronous machine; V dcn is the rated DC voltage; s is the differential operator.

[0056] Arranging (1.14) we can obtain: (14) We can get Δ θ s , Δ ω d The rates of change with time are: (15) t is time; d is the differential. Taking the derivative of Equation (1.13) with respect to time and substituting it into (15), we can obtain: (16) At this time, the transient energy will continue to decay over time, and this item represents the rate at which the additional virtual damping consumes the transient energy.

[0057] Then, we can differentiate the transient kinetic energy and transient potential energy with respect to time, and we can get: (17) It can be seen that this method actually adds a dissipation term to the transient kinetic energy to achieve the dissipation of transient energy.

[0058] The physical model cannot be changed by control methods. In order to achieve a similar effect to synchronous machine damping in DC voltage synchronous control, additional control must be added to the control loop. First, consider changing the negative feedback damping loop on the capacitor to a positive loop, such as Figure 3 shown.

[0059] In order to achieve the resistance effect in the control loop, the forward loop needs to be moved backward, such as Figure 4 shown.

[0060] This embodiment takes into account that the differential link is difficult to implement in practice and requires other methods to be equivalent. It is considered to be implemented with a high-pass positive feedback loop. k p and a When taking a specific value, the voltage-angular velocity loop transfer function is Figure 4 The same can achieve the same effect, such as Figure 5 shown.

[0061] at this time (18) Available (19) The dynamic changes of high-pass filter feedback value and DC voltage difference are as follows: Figure 6 As shown. DC voltage synchronous control output Δ ω d Dynamic Figure 7 shown.

[0062] It can be seen that when the input power changes, the existence of the feedback loop first causes the angular velocity to change faster, and then it changes in the opposite trend to the DC voltage difference, offsetting the oscillation, making the oscillation of the angular velocity smaller and smaller, achieving a damping effect.

[0063] This embodiment analyzes the energy transfer process of a DC voltage synchronous control converter and defines transient energy related to oscillation intensity, which manifests as the mutual conversion of potential energy and kinetic energy. Under small disturbances, transient potential energy undergoes a sudden change and is exchanged with transient kinetic energy. This reveals the nature of low-frequency oscillations in DC voltage synchronous control. Based on this, the additional transient kinetic energy dissipation control strategy of this embodiment directly dissipates transient kinetic energy, significantly reducing the oscillation intensity and duration of DC voltage synchronous control under small signal disturbances.

[0064] The following tests are conducted in combination with the above-mentioned DC voltage synchronous control oscillation suppression method based on transient kinetic energy dissipation, such as Figure 8 As shown, the theoretical calculation results are shown in Table 1, which shows the DC voltage synchronization control parameters.

[0065] Table 1

[0066] Perform transient energy analysis on the DC voltage synchronous control at this time: (twenty one) Arranging (21), we can get: (twenty two) We can get Δ θ s , Δ V dc The rates of change with time are: (twenty three) Taking the derivative of Equation (13) with respect to time and substituting it into (23), we can obtain the derivatives of transient kinetic energy and transient potential energy with respect to time: (twenty four) At this time, the rate of change of transient energy with time is: (25) It can be seen that a new energy dissipation term appears in the transient kinetic energy at this time. The transient kinetic energy will continue to decay over time until it reaches zero, thus achieving the suppression of oscillation.

[0067] Simulate and analyze transient energy, such as Figure 9 shown. Figure 9Figure 2 shows the change in transient energy in a DC voltage synchronously controlled grid-connected system with an additional transient kinetic energy suppression strategy. It can be seen that at the moment of a power step, the transient kinetic energy increases significantly due to the change in the steady-state phase angle. The proposed transient kinetic energy suppression strategy significantly suppresses this transient energy, rapidly reducing it to near zero within a relatively short period of time.

[0068] In this embodiment, a small disturbance simulation model is built on the Matlab Simulink platform. A transient kinetic energy dissipation strategy is added to this model, and the power response characteristics are compared and analyzed to verify the effect of the control strategy.

[0069] At 0.5s, a 10000W step is given to the input power, and the method without additional control strategy is used as the comparison object. Figure 10 The figure shows the active output comparison of the control strategies under small disturbances, where the red curve represents the control strategy without additional control, and the blue curve represents the transient kinetic energy suppression strategy. Without the additional control strategy, the negative damping characteristic is obvious, the oscillation continues for a long time and the amplitude continues to increase. After adding the transient kinetic energy suppression strategy, the degree and duration of the oscillation are significantly reduced, and the active power stability rate is significantly improved. Figures 11 to 14 As shown in the figure, the proposed improved control method can make the system reach a stable state more quickly.

[0070] The following is an embodiment of a DC voltage synchronous control oscillation suppression system based on transient kinetic energy dissipation provided by an embodiment of the present disclosure. This system and the DC voltage synchronous control oscillation suppression method based on transient kinetic energy dissipation in the above-mentioned embodiments belong to the same inventive concept. For details not fully described in the embodiment of the DC voltage synchronous control oscillation suppression system based on transient kinetic energy dissipation, please refer to the embodiment of the DC voltage synchronous control oscillation suppression method based on transient kinetic energy dissipation.

[0071] The system includes: a model equivalence and establishment module, which is used to equate the DC voltage synchronous control converter to a synchronous machine model, define the input power, grid-connected power and equivalent rotational inertia of the synchronous machine model, and establish a power angle dynamic equation based on the angular velocity of the grid. The power angle is composed of the electrical angle difference between the converter and the grid, and the angular velocity dynamics is generated by adjusting the DC voltage deviation through the control coefficient.

[0072] The energy decomposition calculation module is used to decompose the oscillation energy into transient kinetic energy related to the equivalent moment of inertia and transient potential energy related to the power angle offset. The transient potential energy is calculated by integrating the power difference with the power angle.

[0073] The damping control and energy dissipation module is used to define the damping coefficient, make the transient energy decay exponentially over time through closed-loop control, and adjust the damping coefficient based on the differential relationship of the DC voltage deviation to control the energy dissipation rate.

[0074] The compensation channel setting module is used to add a compensation channel in series with a proportional link and a high-pass filter in the control loop. By adjusting the proportional coefficient and high-pass cutoff frequency, the voltage-angular velocity phase characteristic meets the oscillation suppression requirements and realizes the reverse offset of angular velocity and voltage deviations.

[0075] The parameter adaptive adjustment module is used to dynamically adjust the damping coefficient and compensation loop parameters in real time according to the DC voltage fluctuation and frequency deviation, establish an adaptive matching relationship based on the equivalent moment of inertia, maintain the phase compensation effect and suppress the oscillation amplitude.

[0076] Furthermore, as a refinement and expansion of the specific implementation of the above embodiment, in order to fully illustrate the specific implementation process in this embodiment, a specific embodiment is provided below to illustrate the implementation of a DC voltage synchronous control oscillation suppression system based on transient kinetic energy dissipation.

[0077] Consider a 500kW PV grid-connected converter with a DC bus rated voltage Vdcn = 800V and a grid frequency fg = 50Hz (ωg = 100πrad / s). ΔVdc and Δθs are collected in real time to calculate transient kinetic energy and transient potential energy. If transient kinetic energy > 50J is detected, the oscillation suppression logic is triggered.

[0078] The initial setting for the virtual damping coefficient D is 200, linking the damping power term D·Δωd to the differential value of ΔVdc. When ΔVdc fluctuations exceed ±5%, D is automatically increased to 300 to accelerate energy dissipation. The proportional coefficient kp is selected to be 0.5, and the high-pass cutoff frequency a is selected to be 30 Hz, corresponding to twice the dominant oscillation frequency of 15 Hz. Frequency-domain analysis verifies that the voltage-angular velocity transfer function has a phase difference of nearly 180° at 15 Hz, meeting the requirement for reverse cancellation.

[0079] An FFT-based oscillation frequency detection module was deployed. When the oscillation frequency shifted to 20 Hz, it automatically adjusted a to 40 Hz and simultaneously increased kp by 0.6 to maintain phase compensation. Furthermore, D was dynamically adjusted based on the ΔVdc amplitude to ensure transient energy decay time was less than 0.5 seconds. This showed that even with sudden changes in PV output, such as cloud cover causing a ±10% ΔVdc fluctuation, the system oscillation amplitude decayed to below ±2% within 0.2 seconds, validating the effectiveness of the transient kinetic energy dissipation strategy.

[0080] like Figure 15 As shown, the present application also provides an electronic device, including a display module 103, a memory 102, a processor 101, and a computer program stored in the memory and executable on the processor 101. When the processor 101 executes the program, the steps of the DC voltage synchronous control oscillation suppression method based on transient kinetic energy dissipation are implemented.

[0081] In the embodiments of the present invention, electronic devices include, but are not limited to, laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic devices may also represent various forms of mobile devices, such as personal digital assistants, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the embodiments of the present application described and / or claimed herein.

[0082] In the embodiment of the present application, the processor 101 can be implemented by using at least one of a special purpose integrated circuit, a programmable logic device, a field programmable gate array, a processor, a controller, a microcontroller, a microprocessor, and an electronic unit designed to perform the functions described herein. In some cases, such an embodiment can be implemented in a controller. For software implementation, an embodiment such as a process or function can be implemented with a separate software module that allows the execution of at least one function or operation. The software code can be implemented by a software application (or program) written in any appropriate programming language, and the software code can be stored in a memory and executed by a controller.

[0083] The display module 103 is used to display information input by the user or information provided to the user. The display module 103 may include a display panel, which may be configured in the form of a liquid crystal display, an organic light emitting diode, etc.

[0084] The memory 102 can be used to store software programs and various data. The memory 102 can include high-speed random access memory and non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0085] The present application also provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of a method for suppressing oscillations of a DC voltage synchronous control based on transient kinetic energy dissipation.

[0086] The storage medium can be any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or component, or any combination thereof. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof.

[0087] In the context of storage media, a readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, which carries readable program code. This propagated data signal may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable signal medium may also be any readable medium other than a readable storage medium that can transmit, propagate, or transfer a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0088] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for suppressing oscillations of DC voltage synchronous control based on transient kinetic energy dissipation, characterized in that: Methods include: Step S101: Equivalently modeling the DC voltage synchronous control converter as a synchronous machine, defining the input power, grid-connected power, and equivalent moment of inertia of the synchronous machine model, and establishing a power angle dynamic equation based on the grid angular velocity. The power angle is composed of the electrical angle difference between the converter and the grid, and the angular velocity dynamics is generated by adjusting the DC voltage deviation through a control coefficient. Step S102: decomposing the oscillation energy into transient kinetic energy related to the equivalent moment of inertia and transient potential energy related to the power angle offset, wherein the transient potential energy is calculated by integrating the power difference with the power angle; Step S103: defining a damping coefficient, and using a closed-loop control loop to exponentially decay transient energy over time, and adjusting the damping coefficient based on the differential relationship of the DC voltage deviation to control the energy dissipation rate; Step S104: Adding a compensation channel in series with a proportional link and a high-pass filter in the control loop, and adjusting the proportional coefficient and the high-pass cutoff frequency so that the voltage-angular velocity phase characteristic meets the oscillation suppression requirement, thereby achieving reverse cancellation of the angular velocity and voltage deviations; Step S105: dynamically adjusting the damping coefficient and compensation loop parameters in real time according to the DC voltage fluctuation and frequency deviation, establishing an adaptive matching relationship in combination with the equivalent moment of inertia, maintaining the phase compensation effect to suppress the oscillation amplitude.

2. The method for suppressing oscillation of DC voltage synchronous control based on transient kinetic energy dissipation according to claim 1, characterized in that: The equation group of the synchronous machine model in step S101 is: Where, P M 、 P e They are the synchronous machine input motive power and synchronous machine output electromagnetic power respectively; θ m 、 θ g are the angular displacements of the prime mover and the grid, respectively; ω m 、 ω g are the angular velocities of the synchronous machine rotor and the grid, respectively; Express x The differential of J is the moment of inertia of the prime mover; U Modulate the voltage amplitude for the grid-side converter; E is the grid voltage amplitude; X is the reactance between the grid-side converter and the grid synchronous generator; defines the power angle θ s = θ m - θ g .

3. The method for suppressing oscillation of DC voltage synchronous control based on transient kinetic energy dissipation according to claim 1, characterized in that: In step S102, the oscillation energy is decomposed into transient kinetic energy and transient potential energy; Among them, the transient kinetic energy is half of the product of the equivalent moment of inertia and the square of the transient component of angular velocity; The transient potential energy is calculated by integrating the transient component of the power angle on the power-power angle characteristic curve. When the power angle θs deviates from the steady-state value, the potential energy increases linearly with the integral value of the power difference over the power angle.

4. The method for suppressing oscillation of DC voltage synchronous control based on transient kinetic energy dissipation according to claim 3, characterized in that: Grid angular velocity ω g As the angular velocity of the system reference coordinate system, when the system is in a steady state, the transient potential energy is 0. θ s = is the zero point of system potential energy; transient kinetic energy Expressed as: ； The temporary potential energy is: Transient energy of synchronous machine grid-connected system is the sum of transient kinetic energy and transient potential energy, that is: 。 5. The method for suppressing oscillation of DC voltage synchronous control based on transient kinetic energy dissipation according to claim 1, characterized in that: Step S103 specifically includes: introducing a damping coefficient into the equivalent synchronous machine model, multiplying the damping power term by the transient component of the angular velocity and superimposing the resultant product into the angular velocity dynamic equation; designing a control loop so that the time derivative of the transient energy is equal to the product of the negative virtual damping term and the square of the transient component of the angular velocity, thereby ensuring that the transient energy decays exponentially over time, and deriving the differential relationship between the damping power term and the DC voltage deviation, thereby adjusting the energy dissipation rate through the damping coefficient.

6. The method for suppressing oscillation of DC voltage synchronous control based on transient kinetic energy dissipation according to claim 1, characterized in that: Step S104 specifically includes: setting a forward compensation channel in the control loop, and replacing the differential link with a series structure of a proportional link and a high-pass filter; setting the proportional coefficient kp and the high-pass cutoff frequency a so that the compensation loop is equivalent to a virtual damping control structure in the frequency domain characteristics, and adjusting the proportional coefficient kp and the cutoff frequency a of the high-pass filter so that the phase characteristics of the voltage-angular velocity transfer function meet the oscillation suppression requirements, thereby achieving reverse cancellation of the angular velocity change trend and the voltage deviation under input power disturbance.

7. The method for suppressing oscillation of DC voltage synchronous control based on transient kinetic energy dissipation according to claim 1, characterized in that: Step S105 specifically includes: dynamically adjusting the matching relationship between the damping coefficient and the proportional coefficient kp according to the real-time detection values ​​of the DC bus voltage fluctuation amplitude and the grid frequency deviation; establishing a functional relationship between the parameter adjustment factor and the equivalent moment of inertia to ensure the consistency of the transient energy dissipation rate under different working conditions; and adjusting the proportional coefficient kp and the cutoff frequency a of the high-pass filter through an adaptive algorithm to maintain the phase compensation effect of the compensation loop and achieve suppression of the oscillation amplitude.

8. A DC voltage synchronous control oscillation suppression system based on transient kinetic energy dissipation, characterized in that: The system is used to implement the DC voltage synchronous control oscillation suppression method based on transient kinetic energy dissipation as described in any one of claims 1 to 7; The system includes: The model equivalence and establishment module is used to equate the DC voltage synchronous control converter to a synchronous machine model, define the input power, grid-connected power, and equivalent moment of inertia of the synchronous machine model, and establish the power angle dynamic equation based on the grid angular velocity. The power angle is composed of the electrical angle difference between the converter and the grid, and the angular velocity dynamics is generated by adjusting the DC voltage deviation through the control coefficient. Energy decomposition calculation module, used to decompose the oscillation energy into transient kinetic energy related to the equivalent moment of inertia and transient potential energy related to the power angle offset. The transient potential energy is calculated by integrating the power difference with the power angle. The damping control and energy dissipation module is used to define the damping coefficient, make the transient energy decay exponentially over time through closed-loop control, and adjust the damping coefficient based on the differential relationship of the DC voltage deviation to control the energy dissipation rate; The compensation channel setting module is used to add a compensation channel in series with a proportional link and a high-pass filter in the control loop. By adjusting the proportional coefficient and high-pass cutoff frequency, the voltage-angular velocity phase characteristic meets the oscillation suppression requirements and achieves the reverse offset of angular velocity and voltage deviations. The parameter adaptive adjustment module is used to dynamically adjust the damping coefficient and compensation loop parameters in real time according to the DC voltage fluctuation and frequency deviation, establish an adaptive matching relationship based on the equivalent moment of inertia, maintain the phase compensation effect and suppress the oscillation amplitude.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the DC voltage synchronous control oscillation suppression method based on transient kinetic energy dissipation are implemented as described in any one of claims 1 to 7.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for suppressing oscillation of DC voltage synchronous control based on transient kinetic energy dissipation as claimed in any one of claims 1 to 7 are implemented.

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