Damping control method, system, medium and equipment for net-forming type flexible direct current converter

Abstract

The invention discloses a damping control method, a damping control system, a damping control medium and damping control equipment for a grid-forming type flexible direct current converter, and belongs to the field of stability control of a high-voltage direct current transmission system.The damping control method comprises the steps that normalized power deviation is generated based on a reference value and an output value of active power of the grid-forming type flexible direct current converter and rated angular frequency of a grid-connected system; performing deviation superposition processing on the normalized power deviation according to the damping compensation power deviation to obtain a first power deviation, and performing integration on the first power deviation based on an inertia coefficient to obtain an angular frequency deviation; wherein after the angular frequency deviation is generated each time, the damping compensation power deviation is updated; and according to the angular frequency deviation and the output voltage amplitude of the virtual synchronous machine, generating voltage reference data, and further generating a pulse width modulation signal to control the network-forming flexible DC converter. Therefore, by implementing the method and the device, the problem that high-stability and high-precision power control is difficult to realize at the same time by the traditional strategy of the virtual synchronous machine in the prior art can be solved.

Description

Technical Field

[0001] The present invention belongs to the field of stability control of high - voltage direct - current transmission systems, and relates to a damping control method, system, medium and device for a network - forming flexible direct - current converter. Background Art

[0002] Due to its flexible active and reactive power regulation capabilities, the flexible direct - current transmission system has become an important solution for large - scale new - energy integration and regional power - grid interconnection. The traditional flexible direct - current transmission system adopts a vector control strategy based on a phase - locked loop to achieve power control by sampling the phase of the grid - connected voltage. However, in extremely weak operating conditions where the grid strength decreases, the phase - locked loop is difficult to accurately track the grid - voltage phase, which is likely to cause small - signal instability problems. For this reason, network - forming control (such as droop control and virtual - synchronous - machine control) has been proposed to enhance the system support capacity under weak grids. The virtual - synchronous - machine control provides inertial response and dynamic damping for the system by simulating the inertia and damping characteristics of a synchronous generator, and is widely used in weak - grid connection and new - energy grid - connection scenarios.

[0003] However, in the traditional virtual - synchronous - machine control strategy, the selection of the damping coefficient needs to consider both system stability and power - output accuracy. When the system is in the constant - power control mode, if the damping coefficient is set to a high value to ensure stability, it will cause the output power of the flexible direct - current converter to deviate from the command value when the grid frequency fluctuates normally, and the steady - state power deviation may exceed the 1% limit required by national standards; conversely, if the damping coefficient is reduced to give priority to power accuracy, it may trigger the risk of system oscillation. This contradiction makes it difficult for traditional methods to achieve both high stability and high - precision power control under weak - grid operating conditions, restricting the engineering application effect of network - forming converters. Summary of the Invention

[0004] The present application provides a damping control method, system, medium and device for a network - forming flexible direct - current converter, which can solve the problem that the traditional strategy of a virtual synchronous machine in the prior art is difficult to achieve both high stability and high - precision power control.

[0005] To achieve the above object, in the first aspect, the present invention provides a damping control method for a network - forming flexible direct - current converter, including: Generating a normalized power deviation based on the reference value of the active power of the network - forming flexible direct - current converter, the current output value, and the rated angular frequency of the grid - connected system; Based on the preset damping compensation power deviation and the normalized power deviation, perform deviation superposition processing to obtain the first power deviation, and perform integral operation on the first power deviation according to the preset inertia coefficient to obtain the angular frequency deviation; wherein, the damping compensation power deviation is updated according to the angular frequency deviation and the preset angular frequency deviation compensation amount after each generation of the angular frequency deviation; the angular frequency deviation compensation amount is updated according to the first power deviation and the updated damping compensation power deviation after each update of the damping compensation power deviation. Generate voltage reference data according to the angular frequency deviation and the output voltage amplitude of the virtual synchronous machine. Generate a pulse width modulation signal according to the voltage reference data, and control the grid-forming flexible DC converter according to the pulse width modulation signal.

[0006] Compared with the prior art, the embodiments of the present application have the following beneficial effects: By generating a normalized power deviation based on the reference value of the active power of the grid-forming flexible DC converter, the current output value and the rated angular frequency of the grid-connected system, the power deviation is converted into a frequency-related per-unit value to adapt to the dimensional unity requirement of the subsequent control link; By performing deviation superposition processing on the preset damping compensation power deviation and the normalized power deviation to form a closed-loop feedback mechanism, the transient response speed is enhanced; By performing integral operation on the first power deviation with the preset inertia coefficient to simulate the mechanical inertia characteristics of the synchronous generator and suppress the power oscillation caused by the sudden change of the grid frequency; By dynamically updating the damping compensation power deviation based on the angular frequency deviation and the preset angular frequency deviation compensation amount, the damping compensation amount is adjusted in real time to optimize the transient damping performance; By updating the angular frequency deviation compensation amount based on the first power deviation and the updated damping compensation power deviation, the integral compensation is combined to eliminate the steady-state power deviation and improve the control accuracy; By integrating the angular frequency deviation and the output voltage amplitude to generate voltage reference data suitable for the current working condition, the real-time matching of the power command and the system state is ensured; The voltage reference data is converted into a pulse width modulation signal, and the output of the converter is dynamically adjusted based on the modulation signal to ensure the rapid tracking of the active power and the grid frequency, and improve the transient response speed and the steady-state execution efficiency. Through the collaborative combination design of the above features, a local negative feedback is constructed inside the damping link to avoid the direct feedback of the angular frequency deviation, improve the steady-state power control accuracy and enhance the transient damping, and solve the contradiction between stability and accuracy in the traditional virtual synchronous machine control.

[0007] In some embodiments of the first aspect of the present application, the generating of the normalized power deviation based on the reference value of the active power of the grid-forming flexible DC converter, the current output value and the rated angular frequency of the grid-connected system includes: Perform deviation operation on the reference value of the active power of the grid-forming flexible DC converter and the current output value to obtain the original power deviation. Normalize the original power deviation according to the rated angular frequency of the grid-connected system to obtain a normalized power deviation.

[0008] Compared with the prior art, the above embodiments have the following beneficial effects: By performing a deviation operation on the active power reference value and the current output value of the grid-forming flexible DC converter to obtain the original power deviation, directly extracting the instantaneous error signal between the power command and the actual output, providing the basic input for closed-loop control; By normalizing the original power deviation based on the rated angular frequency of the grid-connected system, eliminating the dimensional difference in different grid frequency scenarios, and improving the cross-condition universality of the control strategy.

[0009] In some embodiments of the first aspect of the present application, after each generation of the angular frequency deviation, the damping compensation power deviation is updated according to the angular frequency deviation and a preset angular frequency deviation compensation amount, including: After each generation of the angular frequency deviation, perform a damping ratio operation on the angular frequency deviation and the angular frequency deviation compensation amount according to the damping coefficient of the virtual synchronous machine to obtain an updated damping compensation power deviation; wherein, the formula for the damping ratio operation is: ; wherein, represents the damping compensation power deviation, D represents the damping coefficient, represents the angular frequency deviation, represents the angular frequency deviation compensation amount.

[0010] Compared with the prior art, the above embodiments have the following beneficial effects: By performing a damping ratio operation on the angular frequency deviation and the angular frequency deviation compensation amount according to the damping coefficient of the virtual synchronous machine after each generation of the angular frequency deviation, quantifying the dynamic deviation weight using the damping coefficient, and quickly adjusting the damping compensation power deviation to suppress transient power fluctuations.

[0011] In some embodiments of the first aspect of the present application, after each update of the damping compensation power deviation, the angular frequency deviation compensation amount is updated according to the first power deviation and the updated damping compensation power deviation, including: After each update of the damping compensation power deviation, perform a joint integral compensation operation according to a preset adjustment coefficient, the first power deviation, and the updated damping compensation power deviation to obtain an updated angular frequency deviation compensation amount; wherein, the formula for the joint integral compensation operation is: ; wherein, K represents the adjustment coefficient, s represents the Laplace operator, represents the first power deviation.

[0012] Compared with the prior art, the above embodiments have the following beneficial effects: After each update of the damping compensation power deviation, a joint integral compensation operation is performed according to a preset adjustment coefficient, a first power deviation, and the updated damping compensation power deviation. The steady-state error is gradually eliminated through the integral action to ensure that the power output strictly tracks the command value. By jointly adjusting the forward power deviation and the feedback compensation amount, a dynamic compensation mechanism is formed to enhance the system's adaptive correction ability for long-term deviations.

[0013] In some embodiments of the first aspect of the present application, generating voltage reference data according to the angular frequency deviation and the output voltage amplitude of the virtual synchronous machine includes: Performing a phase synthesis integral operation on the angular frequency deviation and the rated angular frequency to generate the output phase of the virtual synchronous machine; Performing a polar coordinate transformation process according to the output voltage amplitude of the virtual synchronous machine and the output phase to generate a first voltage reference value and a second voltage reference value as voltage reference data.

[0014] Compared with the prior art, the above embodiments have the following beneficial effects: By integrating the dynamic angular frequency deviation and the rated angular frequency, a continuous phase signal synchronized with the power grid is generated to ensure that the output phase of the virtual synchronous machine dynamically matches the power grid reference frequency, thereby improving the synchronization stability under a weak power grid; the integral operation smooths the angular frequency mutation and suppresses the power oscillation caused by the transient phase jump. Converting the output voltage amplitude and phase in the polar coordinate system into voltage reference values in the stationary coordinate system to adapt to the requirements of the converter modulation algorithm and achieve an accurate mapping from the power control command to the voltage waveform; the polar coordinate transformation retains the orthogonal characteristics of the amplitude and phase through trigonometric function operations to ensure the amplitude consistency and phase continuity of the voltage reference value, thereby improving the quality of the converter output waveform and the dynamic tracking accuracy.

[0015] In a second aspect, the present invention also provides a grid-forming flexible DC converter damping control system, including: a normalized power deviation calculation module, an angular frequency deviation calculation module, a voltage data generation module, and a signal control module; Among them, the normalized power deviation calculation module is used to generate a normalized power deviation based on the reference value of the active power of the grid-forming flexible DC converter, the current output value, and the rated angular frequency of the grid-connected system; The angular frequency deviation calculation module is used to perform deviation superposition processing on the preset damping compensation power deviation and the normalized power deviation to obtain a first power deviation, and perform integral operation on the first power deviation according to the preset inertia coefficient to obtain an angular frequency deviation; wherein, the damping compensation power deviation is updated according to the angular frequency deviation and the preset angular frequency deviation compensation amount after each generation of the angular frequency deviation; the angular frequency deviation compensation amount is updated according to the first power deviation and the updated damping compensation power deviation after each update of the damping compensation power deviation; The voltage data generation module is used to generate voltage reference data according to the angular frequency deviation and the output voltage amplitude of the virtual synchronous machine; The signal control module is used to generate a pulse width modulation signal according to the voltage reference data, and control the grid-connected modular multilevel converter according to the pulse width modulation signal.

[0016] Compared with the prior art, the above embodiments of the present application have the following beneficial effects: By generating a normalized power deviation based on the active power reference value, the current output value of the grid-connected modular multilevel converter, and the rated angular frequency of the grid-connected system, the power deviation is converted into a frequency-related per-unit value to adapt to the dimensional unity requirement of the subsequent control link; By performing deviation superposition processing on the preset damping compensation power deviation and the normalized power deviation to form a closed-loop feedback mechanism, the transient response speed is enhanced; By performing integral operation on the first power deviation with the preset inertia coefficient to simulate the mechanical inertia characteristics of the synchronous generator, the power oscillation caused by the sudden change of the grid frequency is suppressed; By dynamically updating the damping compensation power deviation based on the angular frequency deviation and the preset angular frequency deviation compensation amount, the damping compensation amount is adjusted in real time to optimize the transient damping performance; By updating the angular frequency deviation compensation amount based on the first power deviation and the updated damping compensation power deviation, the steady-state power deviation is eliminated by combined integral compensation to improve the control accuracy; By integrating the angular frequency deviation and the output voltage amplitude to generate voltage reference data suitable for the current working condition, the real-time matching of the power command and the system state is ensured; The voltage reference data is converted into a pulse width modulation signal, and the output of the converter is dynamically adjusted based on the modulation signal to ensure the rapid tracking of the active power and the grid frequency, and improve the transient response speed and the steady-state execution efficiency. Through the collaborative combination design of the above features, a local negative feedback is constructed inside the damping link to avoid the direct feedback of the angular frequency deviation, improve the steady-state power control accuracy and transient damping enhancement, and solve the contradiction problem between stability and accuracy in the traditional virtual synchronous machine control.

[0017] In some embodiments of the second aspect of the present application, the normalized power deviation calculation module includes: an original power deviation calculation unit and a normalization processing unit; Among them, the original power deviation calculation unit is used to perform a deviation operation on the reference value and the current output value of the active power of the network-forming flexible DC converter to obtain the original power deviation; The normalization processing unit is used to normalize the original power deviation according to the rated angular frequency of the grid-connected system to obtain the normalized power deviation.

[0018] Compared with the prior art, the above embodiments have the following beneficial effects: By performing a deviation operation on the reference value and the current output value of the active power of the network-forming flexible DC converter to obtain the original power deviation, the instantaneous error signal between the power command and the actual output is directly extracted, providing the basic input for closed-loop control; By normalizing the original power deviation based on the rated angular frequency of the grid-connected system, the dimension difference in different grid frequency scenarios is eliminated, and the cross-condition universality of the control strategy is improved.

[0019] In some embodiments of the second aspect of the present application, the angular frequency deviation calculation module includes: a first update unit; Among them, the first update unit is used to perform a damping ratio operation on the angular frequency deviation and the angular frequency deviation compensation amount according to the damping coefficient of the virtual synchronous machine after each generation of the angular frequency deviation to obtain the updated damping compensation power deviation; where the formula for the damping ratio operation is: ; where represents the damping compensation power deviation, D represents the damping coefficient, represents the angular frequency deviation, represents the angular frequency deviation compensation amount.

[0020] Compared with the prior art, the above embodiments have the following beneficial effects: By performing a damping ratio operation on the angular frequency deviation and the angular frequency deviation compensation amount according to the damping coefficient of the virtual synchronous machine after each generation of the angular frequency deviation, the dynamic deviation weight is quantified by the damping coefficient, and the damping compensation power deviation is quickly adjusted to suppress the transient power fluctuation.

[0021] In the third aspect, the present invention also provides a network-forming flexible DC converter damping control device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is loaded into the processor, the steps of any one of the network-forming flexible DC converter damping control methods are implemented.

[0022] In the fourth aspect, the embodiments of the present application also provide a computer-readable storage medium, where the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of any one of the network-forming flexible DC converter damping control methods are implemented. Description of the Drawings

[0023] Figure 1 : It is a schematic flow chart of a damping control method for a network-forming flexible DC converter provided in some embodiments of the present invention.

[0024] Figure 2 : It is a schematic structural diagram of a damping control system for a network-forming flexible DC converter provided in some embodiments of the present invention.

[0025] Figure 3 : It is a structural diagram of a damping control device for a network-forming flexible DC converter provided in some embodiments of the present invention.

[0026] Figure 4 : It is a control schematic diagram of a typical virtual synchronous machine provided in some embodiments of the present invention.

[0027] Figure 5 : It is a control schematic diagram of a virtual synchronous machine implementing an optimized damping strategy provided in some embodiments of the present invention.

[0028] Figure 6 : It is a comparison chart of response curves during a power grid frequency step provided in some embodiments of the present invention. Specific Embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0030] Embodiment 1: Please refer to Figure 1 , to solve the problem that the traditional strategy of virtual synchronous machines in the prior art is difficult to achieve both high stability and high-precision power control at the same time, a damping control method for a network-forming flexible DC converter provided in an embodiment of the present invention includes steps S1 to S4: Step S1: Generate a normalized power deviation based on the reference value of the active power of the network-forming flexible DC converter, the current output value, and the rated angular frequency of the grid-connected system.

[0031] Further, step S1 can be implemented through the following preferred embodiments, including steps S11 - S12, specifically as follows: S11: Perform a deviation operation on the reference value and the current output value of the active power of the network-forming flexible DC converter to obtain the original power deviation.

[0032] S12: Normalize the original power deviation according to the rated angular frequency of the grid-connected system to obtain a normalized power deviation.

[0033] In specific implementation, the original power deviation in step S11 and the normalized power deviation in step S12 can be calculated by the following formulas: ; where represents the original power deviation, represents the reference value of the active power of the grid-forming flexible DC converter, represents the output value of the active power of the grid-forming flexible DC converter.

[0034] ; where, represents the normalized power deviation, represents the rated angular frequency of the grid-connected system.

[0035] In this preferred embodiment, steps S11 - S12 obtain the original power deviation through deviation calculation of the reference value and the current output value of the active power of the grid-forming flexible DC converter, directly extract the instantaneous error signal between the power command and the actual output, providing the basic input for closed-loop control; by normalizing the original power deviation based on the rated angular frequency of the grid-connected system, the dimension difference in different power grid frequency scenarios is eliminated, enhancing the cross-condition versatility of the control strategy.

[0036] Step S2: Perform deviation superposition processing on the preset damping compensation power deviation and the normalized power deviation to obtain a first power deviation, and perform integral operation on the first power deviation according to the preset inertia coefficient to obtain an angular frequency deviation; where, the damping compensation power deviation is updated according to the angular frequency deviation and the preset angular frequency deviation compensation amount after each generation of the angular frequency deviation; the angular frequency deviation compensation amount is updated according to the first power deviation and the updated damping compensation power deviation after each update of the damping compensation power deviation.

[0037] In specific implementation, the first power deviation in step S2 can be calculated as follows: ; where, represents the first power deviation, represents the damping compensation power deviation. Specifically, when calculating the first power deviation of the current control cycle, the damping compensation power deviation updated in the previous cycle can be used, and the damping compensation power deviation updated in this cycle will be used in the next cycle, and so on. The specific update method of the damping compensation power deviation can refer to the following step S21.

[0038] In addition, the calculation method of the angular frequency deviation is as follows: ; where represents the angular frequency deviation, J represents the inertia coefficient, and s represents the Laplace operator.

[0039] Furthermore, in step S2, the update of the damping compensation power deviation can be achieved through the following preferred implementation manner, including step S21, specifically as follows: S21: After each generation of the angular frequency deviation, perform a damping proportional operation on the angular frequency deviation and the angular frequency deviation compensation amount according to the damping coefficient of the virtual synchronous machine to obtain the updated damping compensation power deviation; where the formula for the damping proportional operation is: ; where represents the damping compensation power deviation, D represents the damping coefficient, represents the angular frequency deviation, represents the angular frequency deviation compensation amount.

[0040] Similarly, like the damping compensation power deviation, after updating the damping compensation power deviation, the angular frequency deviation compensation amount also needs to be updated, and the specific steps can refer to the following step S22.

[0041] In this preferred embodiment, step S21 performs a damping proportional operation on the angular frequency deviation and the angular frequency deviation compensation amount according to the damping coefficient of the virtual synchronous machine after each generation of the angular frequency deviation, and uses the damping coefficient to quantify the dynamic deviation weight to quickly adjust the damping compensation power deviation to suppress the transient power fluctuation.

[0042] Furthermore, in step S2, the update of the angular frequency deviation compensation amount can be achieved through the following preferred implementation manner, including step S22, specifically as follows: S22: After each update of the damping compensation power deviation, perform a joint integral compensation operation according to the preset adjustment coefficient, the first power deviation, and the updated damping compensation power deviation to obtain the updated angular frequency deviation compensation amount; where the formula for the joint integral compensation operation is: ; where K represents the adjustment coefficient, s represents the Laplace operator, represents the first power deviation.

[0043] In this preferred embodiment, in step S22, after each update of the damping compensation power deviation, a combined integral compensation operation is performed according to a preset adjustment coefficient, a first power deviation, and the updated damping compensation power deviation. The steady-state error is gradually eliminated through the integral action to ensure that the power output strictly tracks the command value. By jointly adjusting the forward power deviation and the feedback compensation amount, a dynamic compensation mechanism is formed to enhance the system's adaptive correction ability for long-term deviations.

[0044] Step S3: Generate voltage reference data according to the angular frequency deviation and the output voltage amplitude of the virtual synchronous machine.

[0045] Further, step S3 can be implemented through the following preferred implementation manners, including steps S31 - S32, specifically as follows: S31: Perform a phase synthesis integral operation on the angular frequency deviation and the rated angular frequency to generate the output phase of the virtual synchronous machine.

[0046] In specific implementation, the output phase can be calculated through the following formula: ; where represents the output phase.

[0047] S32: Perform a polar coordinate transformation process according to the output voltage amplitude of the virtual synchronous machine and the output phase to generate a first voltage reference value and a second voltage reference value as the voltage reference data.

[0048] In specific implementation, the calculation formulas for the first voltage reference value and the second voltage reference value are as follows: ; ; where, and respectively represent the voltage reference value component (i.e., the first voltage reference value) on the stationary coordinate system and the voltage reference value component (i.e., the second voltage reference value), and U represents the output voltage amplitude of the virtual synchronous machine obtained based on the reactive power control of the virtual synchronous machine.

[0049] In this preferred embodiment, steps S31 - S32 generate a continuous phase signal synchronized with the power grid by integrating the synthesized dynamic angular frequency deviation and the rated angular frequency, ensuring that the output phase of the virtual synchronous machine dynamically matches the reference frequency of the power grid, thereby enhancing the synchronization stability under a weak power grid; the integration operation smooths the angular frequency mutation and suppresses the power oscillation caused by the transient phase jump. The output voltage amplitude and phase in the polar coordinate system are converted into voltage reference values in the stationary coordinate system to adapt to the requirements of the converter modulation algorithm, realizing the accurate mapping from the power control command to the voltage waveform; the polar coordinate transformation retains the orthogonal characteristics of the amplitude and phase through trigonometric operations, ensuring the amplitude consistency and phase continuity of the voltage reference value, thereby improving the quality and dynamic tracking accuracy of the converter output waveform.

[0050] Step S4: Generate a pulse width modulation signal according to the voltage reference data, and control the grid-forming VSC based on the pulse width modulation signal.

[0051] In specific implementation, the voltage reference data and can be input into the double closed-loop control system of voltage and current, and a PWM signal (i.e., pulse width modulation signal) is output to control the grid-forming VSC.

[0052] In this embodiment, step S4 converts the voltage reference data into a pulse width modulation signal, dynamically adjusts the converter output based on the modulation signal, ensures the rapid tracking of the active power and the power grid frequency, and improves the transient response speed and steady-state execution efficiency.

[0053] In summary, compared with the prior art, the above embodiments of the present application have the following beneficial effects: By generating a normalized power deviation based on the active power reference value, the current output value of the grid-forming flexible DC converter, and the rated angular frequency of the grid-connected system, the power deviation is converted into a frequency-related per-unit value to adapt to the dimensional unity requirement of the subsequent control link; By performing deviation superposition processing on the preset damping compensation power deviation and the normalized power deviation to form a closed-loop feedback mechanism, the transient response speed is enhanced; By integrating the first power deviation through a preset inertia coefficient to simulate the mechanical inertia characteristics of a synchronous generator and suppressing power oscillations caused by sudden changes in grid frequency; By dynamically updating the damping compensation power deviation based on the angular frequency deviation and a preset angular frequency deviation compensation amount, the damping compensation amount is adjusted in real time to optimize the transient damping performance; By updating the angular frequency deviation compensation amount based on the first power deviation and the updated damping compensation power deviation, integral compensation is combined to eliminate the steady-state power deviation and improve the control accuracy; By integrating the angular frequency deviation and the output voltage amplitude to generate voltage reference data adapted to the current working condition, the real-time matching of the power command and the system state is ensured; The voltage reference data is converted into a pulse width modulation signal, and the output of the converter is dynamically adjusted based on the modulation signal to ensure the rapid tracking of the active power and the grid frequency, and improve the transient response speed and the steady-state execution efficiency. Through the collaborative combination design of the above features, a local negative feedback is constructed inside the damping link to avoid direct feedback of the angular frequency deviation, improve the steady-state power control accuracy and transient damping enhancement, and solve the contradiction problem between stability and accuracy in traditional virtual synchronous machine control.

[0054] Reference Figure 4 to the control schematic diagram of a typical virtual synchronous machine shown in Figure 5 the control schematic diagram of a virtual synchronous machine implementing an optimized damping strategy (i.e., this solution) shown in Figure 6 and the comparison diagram of response curves during a grid frequency step shown in

[0055] From Figure 6 it can be seen that both the original damping strategy and the grid-forming control of the damping link proposed in the present invention generate damping power during a frequency mutation, and this power blocks the sudden change in grid frequency, which is beneficial to the frequency stability of the system. The power deviation of the active power of the original damping strategy reaches 5 MW, while the optimized damping strategy of the present invention returns to the power command value after short-term damping, ensuring the stability of the system power after damping.

[0056] Embodiment 2: Please refer to Figure 2 , based on the same inventive concept, a damping control system for a grid-forming flexible direct current converter disclosed in an embodiment of the present invention includes: a normalized power deviation calculation module M1, an angular frequency deviation calculation module M2, a voltage data generation module M3, and a signal control module M4; Among them, the normalized power deviation calculation module M1 is used to generate a normalized power deviation based on the reference value of the active power of the grid-forming flexible direct current converter, the current output value, and the rated angular frequency of the grid-connected system.

[0057] Further, the normalized power deviation calculation module M1 includes: an original power deviation calculation unit and a normalization processing unit; Among them, the original power deviation calculation unit is used to perform a deviation operation on the reference value of the active power of the grid-forming flexible direct current converter and the current output value to obtain an original power deviation; The normalization processing unit is used to perform normalization processing on the original power deviation according to the rated angular frequency of the grid-connected system to obtain a normalized power deviation.

[0058] In this preferred embodiment, the original power deviation calculation unit and the normalization processing unit obtain the original power deviation through a deviation operation on the reference value of the active power of the grid-forming flexible direct current converter and the current output value, directly extract the instantaneous error signal between the power command and the actual output, and provide the basic input for closed-loop control; by performing normalization processing on the original power deviation based on the rated angular frequency of the grid-connected system, the dimensional difference in different grid frequency scenarios is eliminated, and the cross-condition universality of the control strategy is improved.

[0059] The angular frequency deviation calculation module M2 is used to perform deviation superposition processing on a preset damping compensation power deviation and the normalized power deviation to obtain a first power deviation, and perform integral operation on the first power deviation according to a preset inertia coefficient to obtain an angular frequency deviation; among them, the damping compensation power deviation is updated according to the angular frequency deviation and a preset angular frequency deviation compensation amount each time the angular frequency deviation is generated; the angular frequency deviation compensation amount is updated according to the first power deviation and the updated damping compensation power deviation each time the damping compensation power deviation is updated.

[0060] Further, the angular frequency deviation calculation module M2 includes: a first update unit; Among them, the first update unit is used to perform a damping proportional operation on the angular frequency deviation and the angular frequency deviation compensation amount according to the damping coefficient of the virtual synchronous machine each time the angular frequency deviation is generated to obtain an updated damping compensation power deviation; among them, the formula for the damping proportional operation is: ; wherein, represents the damping compensation power deviation, D represents the damping coefficient, represents the angular frequency deviation, represents the angular frequency deviation compensation amount.

[0061] In this preferred embodiment, after each generation of the angular frequency deviation, the first update unit performs a damping proportional operation on the angular frequency deviation and the angular frequency deviation compensation amount according to the damping coefficient of the virtual synchronous machine, quantifies the dynamic deviation weight by using the damping coefficient, and quickly adjusts the damping compensation power deviation to suppress the transient power fluctuation.

[0062] Further, the angular frequency deviation calculation module M2 further includes: a second update unit; wherein, the second update unit is configured to perform a combined integral compensation operation according to a preset adjustment coefficient, a first power deviation, and the updated damping compensation power deviation after each update of the damping compensation power deviation, so as to obtain an updated angular frequency deviation compensation amount; wherein, the formula for the combined integral compensation operation is: ; wherein, K represents the adjustment coefficient, s represents the Laplace operator, represents the first power deviation.

[0063] In this preferred embodiment, after each update of the damping compensation power deviation, the second update unit performs a combined integral compensation operation according to a preset adjustment coefficient, a first power deviation, and the updated damping compensation power deviation, gradually eliminates the steady-state error through the integral action, and ensures that the power output strictly tracks the command value; by jointly adjusting the forward power deviation and the feedback compensation amount, a dynamic compensation mechanism is formed to enhance the system's adaptive correction ability for long-term deviations.

[0064] The voltage data generation module M3 is configured to generate voltage reference data according to the angular frequency deviation and the output voltage amplitude of the virtual synchronous machine.

[0065] Further, the voltage data generation module M3 includes: a phase generation unit and a voltage data generation unit; wherein, the phase generation unit is configured to perform a phase synthesis integration operation on the angular frequency deviation and the rated angular frequency to generate the output phase of the virtual synchronous machine; The voltage data generation unit is configured to perform a polar coordinate transformation process according to the output voltage amplitude of the virtual synchronous machine and the output phase to generate a first voltage reference value and a second voltage reference value as voltage reference data.

[0066] In this preferred embodiment, the phase generation unit and the voltage data generation unit generate a continuous phase signal synchronized with the power grid by integrating the synthesized dynamic angular frequency deviation and the rated angular frequency, ensuring that the output phase of the virtual synchronous machine dynamically matches the reference frequency of the power grid, thereby improving the synchronization stability under a weak power grid; the integration operation smooths the angular frequency mutation and suppresses the power oscillation caused by the transient phase jump. The output voltage amplitude and phase in the polar coordinate system are converted into voltage reference values in the stationary coordinate system to adapt to the requirements of the converter modulation algorithm, realizing the accurate mapping from the power control command to the voltage waveform; the polar coordinate transformation retains the orthogonal characteristics of the amplitude and phase through trigonometric function operations, ensuring the amplitude consistency and phase continuity of the voltage reference value, thereby improving the quality and dynamic tracking accuracy of the converter output waveform.

[0067] The signal control module M4 is used to generate a pulse width modulation signal according to the voltage reference data and control the grid-forming flexible DC converter according to the pulse width modulation signal.

[0068] In this embodiment, the signal control module M4 converts the voltage reference data into a pulse width modulation signal, dynamically adjusts the converter output based on the modulation signal, ensures the rapid tracking of the active power and the power grid frequency, and improves the transient response speed and the steady-state execution efficiency.

[0069] In summary, compared with the prior art, the embodiment of the present application has the following beneficial effects: generating a normalized power deviation based on the active power reference value of the grid-forming flexible DC converter, the current output value and the rated angular frequency of the grid-connected system, converting the power deviation into a per-unit value related to frequency to adapt to the dimensional unity requirement of the subsequent control link; forming a closed-loop feedback mechanism by superimposing the preset damping compensation power deviation and the normalized power deviation to enhance the transient response speed; performing an integration operation on the first power deviation through a preset inertia coefficient to simulate the mechanical inertia characteristics of a synchronous generator and suppress the power oscillation caused by the sudden change of the power grid frequency; dynamically updating the damping compensation power deviation based on the angular frequency deviation and a preset angular frequency deviation compensation amount, and adjusting the damping compensation amount in real time to optimize the transient damping performance; updating the angular frequency deviation compensation amount based on the first power deviation and the updated damping compensation power deviation, and jointly integrating the compensation to eliminate the steady-state power deviation and improve the control accuracy; integrating the angular frequency deviation and the output voltage amplitude to generate voltage reference data adapted to the current working condition to ensure the real-time matching of the power command and the system state; converting the voltage reference data into a pulse width modulation signal and dynamically adjusting the converter output based on the modulation signal to ensure the rapid tracking of the active power and the power grid frequency, and improving the transient response speed and the steady-state execution efficiency. Through the collaborative combination design of the above features, this solution constructs a local negative feedback inside the damping link, avoids the direct feedback of the angular frequency deviation, improves the steady-state power control accuracy and transient damping enhancement, and solves the contradiction problem between stability and accuracy in traditional virtual synchronous machine control.

[0070] Embodiment 3: Figure 3 The structure diagram of a damping control device for a network-forming flexible DC converter of this application is presented. As Figure 3 shown, the damping control device for the network-forming flexible DC converter may include: a processor N1, a memory N2, a data interface N3, and a communication bus N4.

[0071] Among them: The processor N1, the memory N2, and the data interface N3 complete mutual communication through the communication bus N4; the data interface N3 is used for data communication with other devices such as an input device or an output device, etc.; the processor N1 is used to execute the program N5, and specifically can execute the relevant steps in the embodiment of a damping control method for a network-forming flexible DC converter described in any one of the above.

[0072] Specifically, the program N5 may include program code, and this program code includes computer-executable instructions.

[0073] The processor N1 may be a central processing unit CPU, or a specific integrated circuit ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of this application. One or more processors included in the damping control device for the network-forming flexible DC converter may be of the same type of processor, such as one or more CPUs, or may be of different types of processors, such as one or more CPUs and one or more ASICs.

[0074] The memory N2 is used to store the program N5. The memory N2 may include a high-speed RAM memory, and may also include non-volatile memory, such as at least one disk memory.

[0075] The algorithms or displays provided here are not inherently related to any specific computer, virtual system, or other device. In addition, the embodiments of this application are not directed to any specific programming language.

[0076] Embodiment 4: The embodiment of the present invention also provides a computer-readable storage medium. The storage medium stores at least one executable instruction. When the executable instruction runs on a damping control device / system for a network-forming flexible DC converter, it causes the damping control device / system for the network-forming flexible DC converter to execute a damping control method for a network-forming flexible DC converter in any of the above method embodiments.

[0077] In the specification provided herein, a large number of specific details are set forth. However, it will be understood that embodiments of the present application may be practiced without these specific details. Similarly, in order to streamline the present application and assist in understanding one or more of the various inventive aspects, in the above description of the exemplary embodiments of the present application, the various features of the embodiments of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. Among them, the claims following the specific implementation are hereby expressly incorporated into the specific implementation, where each claim itself serves as a separate embodiment of the present application.

[0078] Those skilled in the art can understand that the modules in the devices in the embodiments can be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments can be combined into a module or unit or component, and in addition, they can be divided into multiple sub-modules or sub-units or sub-components. Except that at least some of such features and / or processes or units are mutually exclusive.

Claims

1. A damping control method for a network-forming flexible direct current converter, characterized in that, Including: Generating a normalized power deviation based on the reference value of the active power of the grid-forming flexible DC converter, the current output value, and the rated angular frequency of the grid-connected system; Performing deviation superposition processing according to a preset damping compensation power deviation and the normalized power deviation to obtain a first power deviation, and performing an integral operation on the first power deviation according to a preset inertia coefficient to obtain an angular frequency deviation; wherein, after each generation of the angular frequency deviation, the damping compensation power deviation is updated according to the angular frequency deviation and a preset angular frequency deviation compensation amount; after each update of the damping compensation power deviation, the angular frequency deviation compensation amount is updated according to the first power deviation and the updated damping compensation power deviation; Generating voltage reference data according to the angular frequency deviation and the output voltage amplitude of the virtual synchronous machine; Generating a pulse width modulation signal according to the voltage reference data, and controlling the grid-forming flexible DC converter according to the pulse width modulation signal.

2. The damping control method of a network-forming flexible DC converter according to claim 1, wherein, The generating of the normalized power deviation based on the reference value of the active power of the grid-forming flexible DC converter, the current output value, and the rated angular frequency of the grid-connected system includes: Performing a deviation operation on the reference value and the current output value of the active power of the grid-forming flexible DC converter to obtain an original power deviation; Normalizing the original power deviation according to the rated angular frequency of the grid-connected system to obtain a normalized power deviation.

3. The damping control method of a network-forming flexible direct current converter according to claim 1, characterized in that The updating of the damping compensation power deviation according to the angular frequency deviation and a preset angular frequency deviation compensation amount after each generation of the angular frequency deviation includes: After each generation of the angular frequency deviation, performing a damping ratio operation on the angular frequency deviation and the angular frequency deviation compensation amount according to the damping coefficient of the virtual synchronous machine to obtain an updated damping compensation power deviation; wherein, the formula for the damping ratio operation is: ; wherein, represents the damping compensation power deviation, D represents the damping coefficient, represents the angular frequency deviation, represents the angular frequency deviation compensation amount.

4. The damping control method of a network-forming flexible direct current converter according to claim 3, wherein The updating of the angular frequency deviation compensation amount according to the first power deviation and the updated damping compensation power deviation after each update of the damping compensation power deviation includes: After each update of the damping compensation power deviation, performing a combined integral compensation operation according to a preset adjustment coefficient, the first power deviation, and the updated damping compensation power deviation to obtain an updated angular frequency deviation compensation amount; wherein, the formula for the combined integral compensation operation is: ; where K represents a regulation coefficient, s represents the Laplace operator, represents the first power deviation.

5. The damping control method of a network-forming flexible DC converter according to claim 1, wherein The generating of the voltage reference data according to the angular frequency deviation and the output voltage amplitude of the virtual synchronous machine includes: Performing a phase synthesis integral operation on the angular frequency deviation and the rated angular frequency to generate the output phase of the virtual synchronous machine; Performing a polar coordinate transformation process according to the output voltage amplitude and the output phase of the virtual synchronous machine to generate a first voltage reference value and a second voltage reference value as the voltage reference data.

6. A damping control system for a network-forming flexible DC converter, characterized in that, Including: A normalized power deviation calculation module, an angular frequency deviation calculation module, a voltage data generation module, and a signal control module; wherein, the normalized power deviation calculation module is used to generate a normalized power deviation based on the reference value of the active power of the grid-forming flexible DC converter, the current output value, and the rated angular frequency of the grid-connected system; The angular frequency deviation calculation module is configured to perform deviation superposition processing on the preset damping compensation power deviation and the normalized power deviation to obtain a first power deviation, and perform an integration operation on the first power deviation according to a preset inertia coefficient to obtain an angular frequency deviation; wherein, the damping compensation power deviation is updated according to the angular frequency deviation and a preset angular frequency deviation compensation amount after each angular frequency deviation is generated; the angular frequency deviation compensation amount is updated according to the first power deviation and the updated damping compensation power deviation after each damping compensation power deviation is updated; The voltage data generation module is configured to generate voltage reference data according to the angular frequency deviation and the output voltage amplitude of the virtual synchronous machine; The signal control module is configured to generate a pulse width modulation signal according to the voltage reference data, and control the grid-connected modular multilevel converter according to the pulse width modulation signal; 7. The damping control system of a network-forming flexible DC converter according to claim 6, characterized in that, The normalized power deviation calculation module includes: an original power deviation calculation unit and a normalization processing unit; Wherein, the original power deviation calculation unit is configured to perform a deviation operation on the reference value and the current output value of the active power of the grid-connected modular multilevel converter to obtain an original power deviation; The normalization processing unit is configured to perform normalization processing on the original power deviation according to the rated angular frequency of the grid-connected system to obtain a normalized power deviation; 8. The damping control system of a network-forming flexible DC converter according to claim 6, characterized in that, The angular frequency deviation calculation module includes: a first update unit; Wherein, the first update unit is configured to perform a damping ratio operation on the angular frequency deviation and the angular frequency deviation compensation amount according to the damping coefficient of the virtual synchronous machine after each angular frequency deviation is generated to obtain an updated damping compensation power deviation; wherein, the formula for the damping ratio operation is: ; wherein, represents the damping compensation power deviation, D represents the damping coefficient, represents the angular frequency deviation, represents the angular frequency deviation compensation amount.

9. A damping control device for a network-forming flexible direct current converter, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the computer program is loaded into the processor, it implements the steps of a damping control method for a grid-connected modular multilevel converter according to any one of claims 1-5.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of a damping control method for a grid-connected modular multilevel converter according to any one of claims 1-5.

Images