Bidirectional direct current charging pile voltage ride-through detection and phase compensation method and system

Abstract

The application discloses a kind of two-way direct current charging pile voltage ride-through detection and phase compensation method and system, wherein the method comprises: according to the input grid voltage and grid voltage angular frequency, positive and negative sequence voltage is separated, obtains two sets of quadrature output signal pairs, and generates grid voltage positive sequence component according to two sets of quadrature output signals;According to the grid voltage positive sequence component, generate the first center angular frequency, and carry out integral processing to obtain the phase value;Voltage deviation output by double third-order generalized integrator is obtained, and the second center angular frequency is generated based on the frequency-locked loop strategy according to the voltage deviation and quadrature signal;Whether voltage ride-through occurs is judged according to the first center angular frequency and the second center angular frequency, and when judging that voltage ride-through occurs, the grid voltage angular frequency is adjusted to the second center angular frequency, and after continuing for a first predetermined time, the grid voltage angular frequency is switched to the first center angular frequency.Therefore, not only greatly improve the detection speed, but also reduce the memory occupancy of program.

Description

Technical Field

[0001] This invention relates to the field of voltage ride-through detection technology, specifically to a method and system for voltage ride-through detection and phase compensation of bidirectional DC charging piles. Background Technology

[0002] With the large-scale grid connection of new energy vehicle charging piles, their capacity share in the power system is gradually increasing. Bidirectional DC charging piles typically have both forward charging and reverse discharging capabilities, making reasonable use of the energy storage function of electric vehicle batteries. This can help vehicle owners obtain peak-valley price differences from the grid company, and also provide technical support for the power system's frequency and voltage regulation needs. As low-voltage ride-through standards continue to improve, distributed generation systems are required to maintain grid connection even during grid faults, placing higher demands on phase-locked loops (PLLs) for detecting grid amplitude, phase, and frequency information under various grid fault conditions.

[0003] In related technologies, voltage ride-through detection usually adopts a voltage ride-through (including grid voltage balance and unbalanced ride-through) detection method based on the effective value of grid voltage. Not only is the grid voltage phase error large, but the effective value also needs to be calculated, so the detection speed is slow and the memory usage is large. Summary of the Invention

[0004] To solve the above-mentioned technical problems, this invention provides a voltage ride-through detection and phase compensation method for bidirectional DC charging piles in grid-connected discharge mode. The method determines whether voltage ride-through has occurred based on the first center angular frequency and the second center angular frequency, and performs phase compensation operation, which not only greatly improves the detection speed, but also reduces the program's memory usage.

[0005] The technical solution adopted in this invention is as follows:

[0006] A method for voltage ride-through detection and phase compensation in the grid-connected discharge mode of a bidirectional DC charging pile includes the following steps: S1, based on a dual third-order generalized integrator, the positive and negative sequences of the grid voltage are separated according to the input grid voltage and the grid voltage angular frequency to obtain two sets of quadrature output signal pairs, and corresponding positive-sequence components of the grid voltage are generated according to the two sets of quadrature output signals; wherein, the quadrature output signal pairs include in-phase signals and quadrature signals; S2, a first center angular frequency is generated according to the positive-sequence components of the grid voltage, and the first center angular frequency is integrated to obtain the corresponding phase value; S3, the voltage deviation output by the dual third-order generalized integrator is obtained, and a corresponding second center angular frequency is generated according to the voltage deviation and the quadrature signals based on a frequency-locked loop strategy; S4, it is determined whether voltage ride-through has occurred according to the first center angular frequency and the second center angular frequency, and when it is determined that voltage ride-through has occurred, the grid voltage angular frequency is adjusted to the second center angular frequency, and after a first preset time, the grid voltage angular frequency is switched back to the first center angular frequency.

[0007] In one embodiment of the present invention, step S2 specifically includes the following steps: S21, performing Park transformation on the positive sequence component of the grid voltage to obtain the d-axis voltage component and the q-axis voltage component; S22, performing PI adjustment on the q-axis voltage component to generate a first instantaneous angular frequency; S23, performing a summation operation on the first instantaneous angular frequency and the initial angular frequency to obtain the first center angular frequency.

[0008] In one embodiment of the present invention, step S3 specifically includes the following steps: S31, multiplying the α-axis angular voltage deviation with the α-axis orthogonal signal to generate a first product operation result, and multiplying the β-axis voltage deviation with the β-axis orthogonal signal to generate a second product operation result; S32, obtaining the average value of the first product operation result and the second product operation result, and generating a second instantaneous angular frequency based on the average value by adjusting the integrator; S33, summing the second instantaneous angular frequency and the initial angular frequency to obtain the second center angular frequency.

[0009] In one embodiment of the present invention, step S4 specifically includes the following steps: S41, calculating the absolute value of the difference between the first center angular frequency and the second center angular frequency to generate a corresponding deviation value; S42, determining whether the deviation value is greater than a preset value; S43, if the deviation value is greater than the preset value, determining that voltage ride-through has occurred.

[0010] In one embodiment of the present invention, the preset value is set according to the minimum deviation between the over-frequency / under-frequency protection value and the rated frequency value in the bidirectional DC charging pile grid connection standard.

[0011] A voltage ride-through detection and phase compensation system for a bidirectional DC charging pile in grid-connected discharge mode includes: a first acquisition module, which is used to separate the positive and negative sequences of the grid voltage based on the input grid voltage and the grid voltage angular frequency using a dual third-order generalized integrator, to obtain two sets of quadrature output signal pairs, and to generate corresponding positive-sequence components of the grid voltage based on the two sets of quadrature output signals; wherein, the quadrature output signal pairs include in-phase signals and quadrature signals; a second acquisition module, which is used to generate a first center angular frequency based on the positive-sequence components of the grid voltage, and to integrate the first center angular frequency to obtain a corresponding phase value; a third acquisition module, which is used to acquire the voltage deviation output by the dual third-order generalized integrator, and to generate a corresponding second center angular frequency based on the voltage deviation and the quadrature signals using a frequency-locked loop strategy; and a detection module, which is used to determine whether voltage ride-through has occurred based on the first center angular frequency and the second center angular frequency, and when voltage ride-through is determined to have occurred, to adjust the grid voltage angular frequency to the second center angular frequency, and to switch the grid voltage angular frequency back to the first center angular frequency after a first preset time.

[0012] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the voltage ride-through detection method described above for bidirectional DC charging piles in grid-connected discharge mode.

[0013] A non-transitory computer-readable storage medium storing a computer program that, when executed by a processor, implements the voltage ride-through detection method described above for bidirectional DC charging piles in grid-connected discharge mode.

[0014] The beneficial effects of this invention are:

[0015] The present invention determines whether voltage ride-through has occurred based on the first center angular frequency and the second center angular frequency, which not only greatly improves the detection speed, but also reduces the program's memory usage. Attached Figure Description

[0016] Figure 1 This is a flowchart of a voltage ride-through detection method for a bidirectional DC charging pile in grid-connected discharge mode according to an embodiment of the present invention;

[0017] Figure 2 This is a block diagram of a bidirectional DC charging pile system according to a specific embodiment of the present invention;

[0018] Figure 3 This is a block diagram of voltage ride-through detection and control in grid-connected discharge mode of a bidirectional DC charging pile according to an embodiment of the present invention;

[0019] Figure 4This is a schematic diagram of the specific structure of a dual third-order generalized integrator according to an embodiment of the present invention;

[0020] Figure 5 This is a simulation diagram illustrating the output angular frequency of the DTOGI-FLL method based on dual third-order generalized integrators in a dynamic process of grid voltage according to an embodiment of the present invention.

[0021] Figure 6 This is a simulation diagram of voltage ride-through detection according to an embodiment of the present invention;

[0022] Figure 7 This is a simulation diagram showing the output phase comparison between DTOGI-FLL and conventional DSOGI-PLL phase-locked loops in an embodiment of the present invention when a low-voltage ride-through condition occurs.

[0023] Figure 8 This is a block diagram of the voltage ride-through detection system in the grid-connected discharge mode of a bidirectional DC charging pile according to an embodiment of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Figure 1 This is a flowchart of a voltage ride-through detection method for a bidirectional DC charging pile in grid-connected discharge mode, according to an embodiment of the present invention.

[0026] It should be noted that the present invention can realize voltage ride-through detection in grid-connected discharge mode based on a bidirectional DC charging pile system. In one embodiment of the present invention, the bidirectional DC charging pile system can be as follows: Figure 2As shown, in charging mode, the bidirectional AC-DC module rectifies the AC power from the grid to the Bus (DC bus), and outputs the required voltage for the EVBattery (vehicle battery) through the isolated DC-DC module. In discharging mode, the vehicle-side battery charges the DC bus through the DC-DC module, and then the bidirectional AC-DC module inverts the charge to the AC grid. The Master MCU (main control chip) is responsible for power control and protection functions. In addition to basic charging and discharging functions, in discharging mode, the main control chip executes the corresponding national grid connection standard according to preset national parameters, possessing grid support capabilities. The system control chip ARM interacts with the EVCC (Electric Vehicle Communication Controller) through the SECC (Supply Equipment Communication Controller), receiving charging and discharging commands from the vehicle and transmitting them to the main control MCU via serial communication.

[0027] In order to achieve Figure 2 The bidirectional AC-DC power conversion function requires rapid and accurate detection of the amplitude, phase, and frequency information of the grid voltage, making phase-locked loop (PLL) technology a crucial component. However, when grid voltage ride-through or grid voltage imbalance occurs, the voltage vector lacks a constant amplitude and frequency, necessitating the separation of the positive and negative sequence components and using the positive sequence fundamental frequency component to obtain the phase and frequency information of the grid voltage. To improve the PLL accuracy and detection speed during grid voltage ride-through, this invention proposes a voltage ride-through detection and phase compensation method for bidirectional DC charging piles in grid-connected discharge mode.

[0028] like Figure 1 As shown, the voltage ride-through detection and phase compensation method for bidirectional DC charging piles in grid-connected discharge mode according to an embodiment of the present invention may include the following steps:

[0029] S1, based on the dual third-order generalized integrator, separates the positive and negative sequences of the grid voltage according to the input grid voltage and the grid voltage angular frequency to obtain two sets of quadrature output signal pairs, and generates the corresponding positive sequence components of the grid voltage according to the two sets of quadrature output signals; wherein, the quadrature output signal pairs include in-phase signals and quadrature signals.

[0030] Specifically, such as Figure 3 As shown in the dashed box corresponding to number ①, the input of the dual third-order generalized integrator (DTOGI) is the grid voltage. (include Axis grid voltage and Axis grid voltage and grid voltage angular frequency (That is, the grid voltage angular frequency output at the previous moment using the voltage ride-through detection and phase compensation method, wherein the initial grid voltage angular frequency can be set at the initial moment), the output consists of two sets of quadrature output signal pairs and the voltage deviation. The quadrature output signal pairs include in-phase signals. and orthogonal signals In-phase signal and orthogonal signals The phases are 90° apart, but the amplitudes are the same. Specifically, in-phase signals... and orthogonal signals May include In-phase signal and Orthogonal signals as well as In-phase signal and Orthogonal signals Voltage deviation May include Shaft voltage deviation and Shaft voltage deviation .

[0031] In one embodiment of the present invention, the specific structure of the dual third-order generalized integrator can be as follows: Figure 4 As shown, the grid voltage In-phase signal from the previous moment Voltage deviation can be generated after performing the difference calculation. In terms of grid voltage and grid voltage angular frequency After performing operations such as difference, product, and integration, an in-phase signal can be generated. and orthogonal signals .

[0032] Furthermore, the positive sequence component of the grid voltage may include Positive sequence component of grid voltage and Positive sequence component of grid voltage Specifically, such as Figure 3 As shown, after acquiring two sets of orthogonal output signals, the calculation is performed. In-phase signal and Orthogonal signals Half of the difference is generated Positive sequence component of grid voltage and calculate Orthogonal signals and In-phase signal The average value is used to generate Positive sequence component of grid voltage .

[0033] S2 generates a first center angular frequency based on the positive sequence component of the grid voltage, and integrates the first center angular frequency to obtain the corresponding phase value.

[0034] In one embodiment of the present invention, step S2 specifically includes the following steps:

[0035] S21, perform Park transformation on the positive sequence component of the grid voltage to obtain the d-axis voltage component and the q-axis voltage component.

[0036] S22, PI adjustment is performed on the q-axis voltage component to generate the first instantaneous angular frequency;

[0037] S23, sum the first instantaneous angular frequency and the initial angular frequency to obtain the first center angular frequency.

[0038] Specifically, such as Figure 3 As shown, firstly, the positive sequence component of the grid voltage (including...) Positive sequence component of grid voltage and Positive sequence component of grid voltage Perform Park transform to obtain the d-axis voltage component. and q-axis voltage component Secondly, take the q-axis voltage component. PI control is performed to generate the first instantaneous angular frequency, and finally the first instantaneous angular frequency and the initial angular frequency are compared. Perform a summation operation to obtain the first center angular frequency. .

[0039] Furthermore, regarding the first center angular frequency Perform integration to obtain the corresponding phase value. Among them, the phase value Input the controller to perform the corresponding PFC control.

[0040] Therefore, the orthogonal signal of the present invention The calculation method has the following advantages: (1) The gain of the DC component is 0, which suppresses the influence of the DC component of the voltage; (2) Compared with the second-order generalized integrator, the transfer function of the double third-order generalized integrator adds a pole, which reduces the output overshoot in the dynamic process; (3) The control strategy of adaptively adjusting the center frequency of the double third-order generalized integrator is adopted, which reduces the deviation between the output frequency and the actual frequency when the grid frequency changes, thereby reducing the deviation between the output phase and the actual phase.

[0041] S3, obtain the voltage deviation of the output of the dual third-order generalized integrator, and generate the corresponding second center angular frequency based on the voltage deviation and the orthogonal signal according to the frequency-locked loop strategy.

[0042] In one embodiment of the present invention, step S3 specifically includes the following steps:

[0043] S31, multiply the α-axis voltage deviation with the α-axis orthogonal signal to generate the first product operation result, and multiply the β-axis voltage deviation with the β-axis orthogonal signal to generate the second product operation result.

[0044] S32, obtain the average value of the first product operation result and the second product operation result, and generate the second instantaneous angular frequency based on the average value by adjusting the integrator.

[0045] S33, sum the second instantaneous angular frequency and the initial angular frequency to obtain the second center angular frequency.

[0046] Specifically, such as Figure 3 As shown in the figure, the dashed box corresponding to serial number ② indicates that the α-axis voltage deviation will first be... Signals orthogonal to the α-axis Perform a product operation to generate the first product result, and then calculate the β-axis voltage deviation. Signals orthogonal to the β axis First, a product operation is performed to generate a second product result. Next, the average of the first and second product results is obtained, and based on the adjustment of the integrator, the average is used to generate a second instantaneous angular frequency. Specifically, the average value can first be input into the controller for dynamic correction, then the corrected value is multiplied by the normalized angular frequency value, and the product result is integrated to generate the second instantaneous angular frequency. Finally, the second instantaneous angular frequency and the initial angular frequency are compared... Perform a summation operation to obtain the second center angular frequency. The normalized value of the angular frequency is: ,in, Indicates the previous moment Positive sequence component of the grid voltage. Indicates the previous moment Positive sequence component of the grid voltage. This represents the second center angular frequency at the previous moment.

[0047] It should be noted that the phase of the voltage deviation output by the dual third-order generalized integrator undergoes a 180° phase jump at the center frequency of the frequency-locked loop, i.e., the second center angular frequency. Specifically, when the angular frequency of the input signal is less than the second center angular frequency, the voltage deviation is perpendicular to the signal. In phase; when the angular frequency of the input signal is greater than the second center angular frequency, the voltage deviation is in sync with the quadrature signal. Inverted, simulation results are as follows Figure 5 As shown, under the same control parameters, when a low voltage ride-through with a DC component occurs at 0.4s, compared with the phase-locked loop (DSOGI-PLL) and frequency-locked loop (DSOGI-FLL) based on DSOGI (Dual Second-Order Generalized Integrator), the DTOGI-FLL (frequency-locked loop based on dual third-order generalized integrator) scheme designed in this invention has a smaller overshoot of the output angular frequency during the grid voltage dynamic process.

[0048] S4, determine whether voltage ride-through has occurred based on the first center angular frequency and the second center angular frequency, and when voltage ride-through is determined to have occurred, adjust the grid voltage angular frequency to the second center angular frequency, and after a first preset time, switch the grid voltage angular frequency back to the first center angular frequency.

[0049] In one embodiment of the present invention, step S4 specifically includes the following steps:

[0050] First, calculate the first center angular frequency. Second center angular frequency The absolute value of the difference is used to generate the corresponding deviation value. ,Right now Then, determine the deviation value. Whether it exceeds a preset value, where the preset value can be set according to the minimum deviation between the over-frequency / under-frequency protection value and the rated frequency value in the bidirectional DC charging pile grid connection standard (multiple countries' bidirectional DC charging pile grid connection standards). For example, the preset value can be 2π × 0.1. Where the deviation value... If the value exceeds a preset value, a voltage ride-through is determined to have occurred. The corresponding simulation results are as follows: Figure 6 As shown. At this time, the center frequency of the phase-locked loop (i.e., the grid voltage angular frequency) can be obtained from the angular frequency output by the DTOGI-PLL. Figure 3 The output of number ① is the first center angular frequency. Switch to DTOGI-FLL output angular frequency ( Figure 3 The output of number ② in the middle, the second center angular frequency After a first preset time (the dynamic response time of the phase-locked loop, for example, 25ms), the output angular frequency (first center angular frequency) of the DTOGI-PLL (phase-locked loop based on dual third-order generalized integrator) is switched to. When a low-voltage ride-through condition containing a DC component occurs, the output phase comparison of this invention with that of a conventional DSOGI-PLL phase-locked loop is as follows: Figure 7 Simulation results show that this method helps reduce phase error during voltage ride-through and improves control accuracy.

[0051] In summary, this invention employs a phase-locked loop (PLL) based on an adaptive dual third-order generalized integrator for phase and frequency detection. During grid voltage ride-throughs (including balanced and unbalanced ride-throughs), it suppresses the influence of the DC voltage component on the frequency and phase of the grid voltage detected by the digital PLL. Furthermore, it utilizes a frequency-locked PLL based on an adaptive dual third-order generalized integrator to reduce frequency overshoot and improve controller accuracy during grid voltage ride-throughs (including balanced and unbalanced ride-throughs). A variable-structure PLL design adaptively adjusts the center frequency of the digital PLL when the grid frequency deviates from the rated frequency during grid voltage ride-throughs (including balanced and unbalanced ride-throughs), reducing the deviation between the output phase and the actual phase and improving controller accuracy. Frequency deviation detection is used to determine the timing of voltage ride-throughs (including balanced and unbalanced ride-throughs), improving the controller's detection speed and reducing program memory usage. Finally, the variable-structure PLL design, after detecting a voltage ride-through, uses the output angular frequency of the frequency-locked loop designed in this invention for phase locking until the PLL completes its dynamic response, reducing the deviation between the PLL output phase and the actual phase.

[0052] The voltage ride-through detection and phase compensation method for bidirectional DC charging piles in grid-connected discharge mode according to an embodiment of the present invention uses a dual third-order generalized integrator to separate the positive and negative sequences of the grid voltage based on the input grid voltage and grid voltage angular frequency, obtaining two sets of quadrature output signal pairs. A corresponding positive-sequence component of the grid voltage is generated based on the two sets of quadrature output signals. The quadrature output signal pairs include in-phase and quadrature signals. A first center angular frequency is generated based on the positive-sequence component of the grid voltage, and the first center angular frequency is integrated to obtain the corresponding phase value. The voltage deviation output by the dual third-order generalized integrator is obtained. A second center angular frequency is generated based on the voltage deviation and the quadrature signal using a frequency-locked loop strategy. The method determines whether voltage ride-through has occurred based on the first and second center angular frequencies. If voltage ride-through is detected, the grid voltage angular frequency is adjusted to the second center angular frequency, and after a first preset time, the grid voltage angular frequency is switched back to the first center angular frequency. Therefore, determining whether voltage ride-through has occurred based on the first and second center angular frequencies not only greatly improves the detection speed but also reduces the program's memory footprint.

[0053] Corresponding to the voltage ride-through detection and phase compensation method of the bidirectional DC charging pile in grid-connected discharge mode in the above embodiments, the present invention also proposes a voltage ride-through detection and phase compensation system for the bidirectional DC charging pile in grid-connected discharge mode.

[0054] like Figure 8As shown, the voltage ride-through detection system of the bidirectional DC charging pile in grid-connected discharge mode according to an embodiment of the present invention may include: a first acquisition module 100, a second acquisition module 200, a third acquisition module 300, and a detection module 400.

[0055] The first acquisition module 100 is used to separate the positive and negative sequences of the grid voltage based on the input grid voltage and grid voltage angular frequency using a dual third-order generalized integrator, to obtain two sets of quadrature output signal pairs, and to generate corresponding positive-sequence components of the grid voltage based on the two sets of quadrature output signals; wherein, the quadrature output signal pairs include in-phase signals and quadrature signals; the second acquisition module 200 is used to generate a first center angular frequency based on the positive-sequence components of the grid voltage, and to perform integration processing on the first center angular frequency to obtain the corresponding phase value; the third acquisition module 300 is used to acquire the voltage deviation output by the dual third-order generalized integrator, and to generate a corresponding second center angular frequency based on the voltage deviation and quadrature signals using a frequency-locked loop strategy; the detection module 400 is used to determine whether voltage ride-through has occurred based on the first center angular frequency and the second center angular frequency, and when voltage ride-through is determined to have occurred, to adjust the grid voltage angular frequency to the second center angular frequency, and after a first preset time, to switch the grid voltage angular frequency back to the first center angular frequency.

[0056] In one embodiment of the present invention, the second acquisition module 200 is specifically used to: perform Park transformation on the positive sequence component of the grid voltage to obtain the d-axis voltage component and the q-axis voltage component; perform PI adjustment on the q-axis voltage component to generate a first instantaneous angular frequency; and perform a summation operation on the first instantaneous angular frequency and the initial angular frequency to obtain a first center angular frequency.

[0057] In one embodiment of the present invention, the third acquisition module 300 is specifically used to: multiply the α-axis voltage deviation with the α-axis orthogonal signal to generate a first product operation result, and multiply the β-axis voltage deviation with the β-axis orthogonal signal to generate a second product operation result; obtain the average value of the first product operation result and the second product operation result, and generate a second instantaneous angular frequency based on the average value by adjusting the integrator; and sum the second instantaneous angular frequency and the initial angular frequency to obtain a second center angular frequency.

[0058] In one embodiment of the present invention, the detection module 400 is specifically used to: calculate the absolute value of the difference between the first center angular frequency and the second center angular frequency to generate a corresponding deviation value; determine whether the deviation value is greater than a preset value; if the deviation value is greater than the preset value, determine that voltage ride-through has occurred.

[0059] In one embodiment of the present invention, a preset value is set according to the minimum deviation between the over-frequency / under-frequency protection value and the rated frequency value in the bidirectional DC charging pile grid connection standard.

[0060] It should be noted that for details not disclosed in the voltage ride-through detection and phase compensation system of the bidirectional DC charging pile in grid-connected discharge mode in the embodiments of the present invention, please refer to the details disclosed in the above-described method for voltage ride-through detection and phase compensation in the bidirectional DC charging pile in grid-connected discharge mode, which will not be elaborated here.

[0061] According to an embodiment of the present invention, a voltage ride-through detection system for a bidirectional DC charging pile in grid-connected discharge mode uses a first acquisition module to separate the positive and negative sequences of the grid voltage based on the input grid voltage and grid voltage angular frequency using a dual third-order generalized integrator, thereby obtaining two sets of quadrature output signal pairs. The system then generates corresponding positive-sequence components of the grid voltage based on these two sets of quadrature output signals. Each quadrature output signal pair includes an in-phase signal and a quadrature signal. A second acquisition module generates a first center angular frequency based on the positive-sequence components of the grid voltage and integrates the first center angular frequency to obtain the corresponding phase value. A third acquisition module acquires the voltage deviation output by the dual third-order generalized integrator, generates a corresponding second center angular frequency based on the voltage deviation and the quadrature signals using a frequency-locked loop strategy, and a detection module determines whether voltage ride-through has occurred based on the first and second center angular frequencies. If voltage ride-through is detected, the grid voltage angular frequency is adjusted to the second center angular frequency, and after a first preset time, the grid voltage angular frequency is switched back to the first center angular frequency. Therefore, determining whether voltage ride-through has occurred based on the first and second center angular frequencies significantly improves the detection speed and reduces the program's memory footprint.

[0062] Corresponding to the voltage ride-through detection method of the bidirectional DC charging pile in the grid-connected discharge mode of the above embodiments, the present invention also proposes a computer device.

[0063] The computer device of this invention includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the voltage ride-through detection method under the grid-connected discharge mode of the bidirectional DC charging pile described above.

[0064] The computer device according to embodiments of the present invention determines whether voltage ride-through has occurred based on a first center angular frequency and a second center angular frequency, which not only greatly improves the detection speed but also reduces the program's memory occupancy.

[0065] Corresponding to the voltage ride-through detection method of the bidirectional DC charging pile in the grid-connected discharge mode of the above embodiments, the present invention also proposes a non-transitory computer-readable storage medium.

[0066] The non-transitory computer-readable storage medium of this invention stores a computer program that, when executed by a processor, implements the voltage ride-through detection method under the grid-connected discharge mode of the bidirectional DC charging pile described above.

[0067] According to embodiments of the present invention, a non-transitory computer-readable storage medium determines whether voltage ride-through has occurred based on a first center angular frequency and a second center angular frequency, which not only greatly improves the detection speed but also reduces the program's memory footprint.

[0068] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. "A plurality of" means two or more, unless otherwise explicitly specified.

[0069] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0070] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0071] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0072] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0073] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for voltage ride-through detection and phase compensation of bidirectional DC charging piles, characterized in that, Includes the following steps: S1, based on the dual third-order generalized integrator, separates the positive and negative sequences of the grid voltage according to the input grid voltage and grid voltage angular frequency to obtain two sets of quadrature output signal pairs, and generates corresponding grid voltage positive sequence components according to the two sets of quadrature output signals; wherein, the quadrature output signal pairs include in-phase signals and quadrature signals; S2, generate a first center angular frequency based on the positive sequence component of the grid voltage, and perform integration processing on the first center angular frequency to obtain the corresponding phase value; S3, obtain the voltage deviation output by the dual third-order generalized integrator, and generate the corresponding second center angular frequency based on the voltage deviation and the orthogonal signal according to the frequency-locked loop strategy; S4, determine whether voltage ride-through has occurred based on the first center angular frequency and the second center angular frequency, and when voltage ride-through is determined to have occurred, adjust the grid voltage angular frequency to the second center angular frequency, and after a first preset time, switch the grid voltage angular frequency back to the first center angular frequency.

2. The method for voltage ride-through detection and phase compensation of bidirectional DC charging piles according to claim 1, characterized in that, Step S2 specifically includes the following steps: S21, Perform Park transformation on the positive sequence component of the grid voltage to obtain the d-axis voltage component and the q-axis voltage component; S22, PI adjustment is performed on the q-axis voltage component to generate the first instantaneous angular frequency; S23, sum the first instantaneous angular frequency and the initial angular frequency to obtain the first center angular frequency.

3. The method for voltage ride-through detection and phase compensation of bidirectional DC charging piles according to claim 1, characterized in that, Step S3 specifically includes the following steps: S31, multiply the α-axis voltage deviation with the α-axis orthogonal signal to generate the first product operation result, and multiply the β-axis voltage deviation with the β-axis orthogonal signal to generate the second product operation result; S32, obtain the average value of the first product operation result and the second product operation result, and generate a second instantaneous angular frequency based on the average value by adjusting the integrator; S33, sum the second instantaneous angular frequency and the initial angular frequency to obtain the second center angular frequency.

4. The method for voltage ride-through detection and phase compensation of bidirectional DC charging piles according to claim 1, characterized in that, Step S4 specifically includes the following steps: S41, calculate the absolute value of the difference between the first center angular frequency and the second center angular frequency to generate the corresponding deviation value; S42, determine whether the deviation value is greater than a preset value; S43, if the deviation value is greater than the preset value, it is determined that voltage ride-through has occurred.

5. The method for voltage ride-through detection and phase compensation of bidirectional DC charging piles according to claim 4, characterized in that, The preset value is set according to the minimum deviation between the over-frequency / under-frequency protection value and the rated frequency value in the bidirectional DC charging pile grid connection standard.

6. A bidirectional DC charging pile voltage ride-through detection and phase compensation system, characterized in that, include: The first acquisition module is used to separate the positive and negative sequences of the grid voltage based on the input grid voltage and grid voltage angular frequency using a dual third-order generalized integrator, so as to obtain two sets of quadrature output signal pairs, and generate corresponding grid voltage positive sequence components based on the two sets of quadrature output signals; wherein, the quadrature output signal pairs include in-phase signals and quadrature signals; The second acquisition module is used to generate a first center angular frequency based on the positive sequence component of the grid voltage, and to perform integration processing on the first center angular frequency to obtain the corresponding phase value. The third acquisition module is used to acquire the voltage deviation output by the dual third-order generalized integrator, and generate a corresponding second center angular frequency based on the voltage deviation and the orthogonal signal according to the frequency-locked loop strategy. The detection module is used to determine whether voltage ride-through has occurred based on the first center angular frequency and the second center angular frequency, and when voltage ride-through is determined to have occurred, to adjust the grid voltage angular frequency to the second center angular frequency, and after a first preset time, to switch the grid voltage angular frequency back to the first center angular frequency.

7. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the bidirectional DC charging pile voltage ride-through detection and phase compensation method according to any one of claims 1-5.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the bidirectional DC charging pile voltage ride-through detection and phase compensation method according to any one of claims 1-5.

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