Phase compensation control method and device of network construction type energy storage converter, and grid-connected system

Abstract

The invention discloses a phase compensation control method and device of a network construction type energy storage converter and a grid-connected system, and belongs to the technical field of network construction control. The method comprises the following steps: acquiring a three-phase voltage of a grid-connected point, and converting the three-phase voltage into a q-axis voltage and a d-axis voltage; calculating a real-time phase of a grid-connected point in real time according to the dq two-axis voltage; sampling q-axis voltage and d-axis voltage according to a preset sampling frequency, and calculating a sampling phase of a grid-connected point in each sampling period; when the absolute value of the difference value between the sampling phase of the current sampling period and the average sampling phase is larger than a first preset phase difference, it is judged that phase jump occurs at the grid-connected point, and the average sampling phase serves as a reference phase; the average sampling phase is an average value of sampling phases of n continuous sampling periods which are located before the current sampling period and are continuous with the current sampling period; and determining a phase compensation angle according to a difference value between the real-time phase and the reference phase, and superposing the phase compensation angle to a phase given value. According to the invention, real-time measurement and compensation of the phase jump of the grid-connected point can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of network-forming control, and in particular, to a phase compensation control method and device for a network-forming energy storage converter, and a grid-connected system. Background Art

[0002] In a power system, the occurrence and removal of a short-circuit fault will both cause a change in the topology of the power grid, thereby resulting in a jump in the amplitude and phase of the grid-connected point voltage of a power conversion system (PCS). Currently, most of the conventional fault ride-through control strategies for network-forming PCSs only consider the impact of amplitude drop during a fault, and do not consider that the change in the external power grid topology will also cause a jump in the grid-connected point voltage phase. This jump will cause an increase in the instantaneous voltage difference between the grid-connected point voltage and the converter port voltage, leading to an overcurrent problem in the converter, which is one of the difficulties that must be overcome in the grid-connected operation of the converter.

[0003] When a phase jump occurs in the power grid, for a network-forming PCS adopting a conventional fault ride-through strategy, the amplitude of its internal electromotive force is quickly changed through the reactive voltage loop control. If the reactive control ability is strong, the reactive power output can quickly reach the reference value requirement, but the phase cannot be quickly changed due to the influence of virtual inertia, and the active power output is difficult to quickly reach the required reference value; in terms of current limiting, when a fault occurs, the equivalent internal electromotive force amplitude quickly decreases under the conventional fault ride-through strategy, but due to the phase jump, there is a certain phase difference between the power grid voltage and the internal electromotive force, so there is still a large voltage difference, and the overcurrent risk cannot be eliminated. Therefore, during the control process of the network-forming PCS, it is urgent to detect and compensate the phase jump angle of the grid-connected point in real time. Summary of the Invention

[0004] The present invention provides a phase compensation control method and device for a network-forming energy storage converter, and a grid-connected system, so as to realize the real-time measurement and timely compensation of the phase jump at the grid-connected point, and improve the operation reliability of the network-forming energy storage converter.

[0005] In a first aspect, an embodiment of the present invention provides a phase compensation control method for a network-forming energy storage converter, including:

[0006] Obtain the three-phase voltages of the grid-connected point of the network-forming energy storage converter, and convert the three-phase voltages into the q-axis voltage and d-axis voltage in a two-phase rotating coordinate system;

[0007] Calculate the real-time phase of the grid-connected point in real time according to the q-axis voltage and the d-axis voltage;

[0008] The q-axis voltage and the d-axis voltage are sampled at a preset sampling frequency, and in any sampling period, a sampling phase of the grid-connected point in the sampling period is calculated based on the sampled q-axis voltage and the d-axis voltage; if the absolute value of the difference between the sampling phase of the current sampling period and the average sampling phase is greater than a first preset phase difference, it is determined that a phase jump has occurred at the grid-connected point and the average sampling phase is used as a reference phase; wherein the average sampling phase is an average of the sampling phases of n consecutive sampling periods that are located before the current sampling period and are continuous with the current sampling period, where n is a positive integer greater than 1;

[0009] A phase compensation angle is determined according to the difference between the real-time phase and the reference phase, and the phase compensation angle is added to the phase given value of the grid-type energy storage converter to compensate for the phase jump of the grid connection point.

[0010] Optionally, converting the three-phase voltage into a q-axis voltage and a d-axis voltage in a two-phase rotating coordinate system includes:

[0011] Based on a locally built phase angle that changes with the power frequency cycle, the three-phase voltage is converted into a q-axis voltage and a d-axis voltage in a two-phase rotating coordinate system through Park transformation.

[0012] Optionally, the real-time phase of the grid connection point is calculated in real time according to the following formula:

[0013] ;

[0014] Among them, θ pcc is the real-time phase, v d is the d-axis voltage, v q is the q-axis voltage.

[0015] Optionally, for the i-th sampling period, the sampling phase of the grid connection point in the i-th sampling period is calculated according to the following formula, where i is a positive integer:

[0016] ;

[0017] Among them, θ i is the sampling phase of the grid-connected point in the i-th sampling period, v di is the d-axis voltage sampled in the i-th sampling period, v qi is the q-axis voltage sampled in the i-th sampling period.

[0018] Optionally, before determining the phase compensation angle according to the difference between the real-time phase and the reference phase, the method further includes:

[0019] When the absolute value of the difference between the sampling phase in the current sampling period and the average sampling phase is less than or equal to the first preset phase difference, it is determined that there is no phase jump at the grid connection point, and the sampling phase in the current sampling period is used as the reference phase.

[0020] Optionally, after determining that there is a phase jump at the grid connection point and using the average sampling phase as the reference phase, it further includes:

[0021] Determine the jump depth identifier according to the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period;

[0022] Determine the gain coefficient according to the jump depth identifier;

[0023] Correspondingly, determining the phase compensation angle according to the difference between the real-time phase and the reference phase includes: determining the phase compensation angle according to the product of the difference between the real-time phase and the reference phase and the gain coefficient.

[0024] Optionally, determining the jump depth identifier according to the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period includes:

[0025] If the absolute value of the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period is greater than the second preset phase difference, set the jump depth identifier to the first preset value; if the absolute value of the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period is less than or equal to the second preset phase difference, set the jump depth identifier to the second preset value; the first preset value is different from the second preset value;

[0026] Or, if the first condition is satisfied, set the jump depth identifier to the first preset value; if the second condition is satisfied, set the jump depth identifier to the second preset value; if neither the first condition nor the second condition is satisfied, control the value of the jump depth identifier to remain unchanged; wherein, the first condition includes: in the first preset number of sampling periods up to the current sampling period, the absolute value of the difference between the sampling phase of each sampling period and the sampling phase of the previous sampling period is greater than the second preset phase difference, and the first preset number is a positive integer greater than 1; the second condition includes: in the second preset number of sampling periods up to the current sampling period, the absolute value of the difference between the sampling phase of each sampling period and the sampling phase of the previous sampling period is less than or equal to the second preset phase difference, and the second preset number is a positive integer greater than 1;

[0027] Determining the gain coefficient according to the jump depth identifier includes:

[0028] If the jump depth identifier is the first preset value, set the gain coefficient to a value greater than 1;

[0029] If the jump depth identifier is the second preset value, set the gain coefficient to 1.

[0030] Optionally, determining the phase compensation angle according to the product of the difference between the real-time phase and the reference phase and the gain coefficient includes:

[0031] Calculate the product of the difference between the real-time phase and the reference phase and the gain coefficient as the compensation angle calculation value;

[0032] If the compensation angle calculation value is between -π / 2 and π / 2, use the compensation angle calculation value as the phase compensation angle;

[0033] If the compensation angle calculation value is less than -π / 2, set the phase compensation angle to -π / 2;

[0034] If the compensation angle calculation value is greater than π / 2, set the phase compensation angle to π / 2.

[0035] In a second aspect, an embodiment of the present invention further provides a phase compensation control device for a grid-forming energy storage converter, including:

[0036] A voltage acquisition module, configured to acquire the three-phase voltage of the grid connection point of the grid-forming energy storage converter, and convert the three-phase voltage into the q-axis voltage and the d-axis voltage in a two-phase rotating coordinate system;

[0037] A real-time phase calculation module, configured to calculate the real-time phase of the grid connection point in real time according to the q-axis voltage and the d-axis voltage;

[0038] A phase jump detection module, configured to sample the q-axis voltage and the d-axis voltage at a preset sampling frequency. In any sampling period, calculate the sampling phase of the grid connection point in the sampling period according to the sampled q-axis voltage and d-axis voltage; when the absolute value of the difference between the sampling phase in the current sampling period and the average sampling phase is greater than the first preset phase difference, determine that a phase jump occurs at the grid connection point and use the average sampling phase as the reference phase; where the average sampling phase is the average value of the sampling phases of consecutive n sampling periods before the current sampling period and consecutive with the current sampling period, and n is a positive integer greater than 1;

[0039] A compensation module, configured to determine a phase compensation angle according to the difference between the real-time phase and the reference phase, and superimpose the phase compensation angle on the phase given value of the grid-forming energy storage converter to compensate for the phase jump at the grid connection point.

[0040] In a third aspect, an embodiment of the present invention further provides a grid-connected system, including: a grid-forming energy storage converter, a power grid, a load, and a controller; the grid-forming energy storage converter is connected to the power grid and the load through the grid connection point of the grid-forming energy storage converter; the controller is connected to the grid-forming energy storage converter, and the controller is configured to control the phase of the grid connection point by using the phase compensation control method of the grid-forming energy storage converter provided in any embodiment of the present invention.

[0041] The phase compensation control method of the grid-forming energy storage converter provided by the embodiment of the present invention can realize the rapid identification and measurement of the phase jump at the grid connection point, and realize the real-time compensation of the phase jump, effectively avoiding the problem that the traditional fault ride-through strategy cannot fully limit the current in the face of the phase jump fault. Specifically, the average sampling phase of the previous continuous n sampling periods of the current sampling period is used as the comparison reference value for comparing with the sampling phase of the current sampling period, which can not only realize the real-time update of the reference value, but also avoid the interference of accidental factors, realize the accurate identification of the phase jump and adjust the reference phase accordingly; the difference between the current real-time phase and the reference phase can characterize the phase jump situation, and adding the determined phase compensation angle to the phase given value for phase control can effectively compensate the phase jump at the grid connection point and improve the operation reliability, stability and safety of the grid-forming energy storage converter.

[0042] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings without creative efforts based on these drawings.

[0044] Figure 1 is a schematic flow chart of a phase compensation control method for a grid-forming energy storage converter provided by an embodiment of the present invention;

[0045] Figure 2 is a flow block diagram of a phase compensation control method for a grid-forming energy storage converter provided by an embodiment of the present invention;

[0046] Figure 3 is a schematic flow chart of a PAJ detection link provided by an embodiment of the present invention;

[0047] Figure 4It is a schematic structural diagram of a phase compensation control device for a grid-forming energy storage converter provided by an embodiment of the present invention. Detailed implementation manners

[0048] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below 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 creative work shall fall within the protection scope of the present invention.

[0049] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0050] An embodiment of the present invention provides a phase compensation control method for a grid-forming energy storage converter, which is applicable to the operation control of the grid-forming energy storage converter during grid connection operation to improve the operation reliability of the grid-forming energy storage converter; this method can be executed by a phase compensation control device of the grid-forming energy storage converter, and the phase compensation control device of the grid-forming energy storage converter can be implemented in the form of hardware and / or software, and this device can be configured in the controller of the grid-connected system / grid-forming energy storage converter.

[0051] Figure 1 It is a schematic flow diagram of a phase compensation control method for a grid-forming energy storage converter provided by an embodiment of the present invention. As Figure 1 shown, the phase compensation control method for the grid-forming energy storage converter includes:

[0052] S110. Obtain the three-phase voltages at the grid connection point of the grid-forming energy storage converter, and convert the three-phase voltages into the q-axis voltage and d-axis voltage in the two-phase rotating coordinate system.

[0053] Among them, the grid connection point is the point where the grid-forming energy storage converter is connected to the grid. The grid-forming energy storage converter can connect the grid and the three-phase load through the grid connection point. Under the grid-connected operation condition, the grid connection point of the grid-forming energy storage converter has three-phase AC voltage. Exemplarily, through transformation processes such as Park transformation, the obtained three-phase voltage can be transformed from the three-phase stationary coordinate system to the q-axis (quadrature axis) voltage and d-axis (direct axis) voltage in the two-phase rotating coordinate system. It can be understood that the steps of obtaining the three-phase voltage and performing coordinate transformation are carried out in real time following the operation process of the grid-forming energy storage converter to collect and analyze the relevant characteristics and operation conditions of the electrical quantities at the grid connection point in real time.

[0054] S120. Calculate the real-time phase of the grid connection point in real time according to the q-axis voltage and d-axis voltage.

[0055] Among them, the real-time phase of the grid connection point is also the real-time phase of the three-phase voltage at the grid connection point. As the grid-forming energy storage converter operates, the three-phase voltage at the grid connection point is continuously updated, and the real-time phase is also updated accordingly. Exemplarily, at any time point, the real-time phase can be calculated according to the arctangent function of the ratio of the q-axis voltage and d-axis voltage at this time point.

[0056] S130. Sample the q-axis voltage and d-axis voltage according to a preset sampling frequency. In any sampling period, calculate the sampling phase of the grid connection point in the sampling period according to the sampled q-axis voltage and d-axis voltage; in the case where the absolute value of the difference between the sampling phase in the current sampling period and the average sampling phase is greater than the first preset phase difference, determine that a phase jump occurs at the grid connection point and use the average sampling phase as the reference phase.

[0057] Among them, the average sampling phase is the average of the sampling phases of consecutive n sampling periods before and consecutive with the current sampling period, where n is a positive integer greater than 1. It can be understood that the calculation process of the sampling phase of each sampling period continues to follow the operation process of the grid-forming energy storage converter, and each sampling period can be sorted in chronological order. The average sampling phase is also a quantity that changes with the operation process of the grid-forming energy storage converter rather than a fixed value. Every time a sampling period elapses, the average sampling phase is recalculated and updated accordingly. For any sampling period, the average sampling phase used for comparison with the sampling phase of this sampling period is the average of the sampling phases in the previous n sampling periods. For example, if the current sampling period is the j-th sampling period in the operation process of the grid-forming energy storage converter, where j is a positive integer greater than n, then the average sampling phase used for comparison with the sampling phase of the current sampling period is the average of the sampling phases from the (j - n)-th to the (j - 1)-th sampling periods. When the absolute value of the difference between the sampling phase of the current sampling period and the average sampling phase is greater than the first preset phase difference, it indicates that the phase change amount at the grid connection point exceeds the normal range, and it can be considered that a phase jump occurs. In this case, the average sampling phase used for comparison in the current sampling period is used as the reference phase for subsequent phase compensation.

[0058] Exemplarily, the preset sampling frequency can be set by comprehensively considering the sampling accuracy requirements (to avoid signal distortion) and the computing power of the controller. For example, it can be set to be greater than 800 Hz, and specifically, it can be 1 kHz. Exemplarily, the calculation of the real-time phase in S120 can also be performed according to the preset sampling frequency. The calculation method of the sampling frequency can be the same as that of the real-time phase to avoid phase errors caused by different calculation methods. The first preset phase difference can be set according to empirical values, or the results of relevant experiments on phase jumps pre-conducted, or relevant data during the historical operation process, and no specific limitation is made here.

[0059] In this step, by comparing the sampling phase of the current sampling period with the average value of the sampling phases of the previous n sampling periods to determine whether a phase jump occurs, compared with only comparing with the sampling phase of the previous sampling period, it can avoid the influence of accidental factors and avoid misjudgment of phase jumps. Among them, the specific value of n can be selected according to actual needs. For example, it can be set in combination with the phase change situation of the grid connection point under ideal conditions and the value of the preset sampling frequency. Specifically, the most suitable value of n can be selected through simulation / experiment. Exemplarily, 5 ≤ n ≤ 15 to avoid the influence of accidental disturbances on the discrimination result of phase jumps due to too small an n value, and to avoid misidentifying the normal phase change as a phase jump due to too long a judgment time interval caused by too large an n value.

[0060] S140. Determine a phase compensation angle based on the difference between the real-time phase and the reference phase, and superimpose the phase compensation angle on the phase given value of the grid-forming energy storage converter to compensate for the phase jump at the grid connection point.

[0061] Among them, the difference between the real-time phase and the reference phase can characterize the phase jump situation at the grid connection point. In practical applications, the above difference can be directly determined as the phase compensation angle, or the phase compensation angle can be formed after processing such as gain on the above difference. The phase given value of the grid-forming energy storage converter can be understood as: the phase control signal input by the active phase link (or phase control unit) originally configured in the controller, which is used to control the phase at the grid connection point. Then, by adjusting the phase given value according to the phase compensation angle, effective compensation for the phase jump can be achieved, and the phase at the grid connection point can be adjusted back to the normal value in a timely manner.

[0062] In summary, the phase compensation control method for the grid-forming energy storage converter provided by the embodiments of the present invention can achieve rapid identification and measurement of the phase jump at the grid connection point, and realize real-time compensation for the phase jump, effectively avoiding the problem that the traditional fault ride-through strategy cannot fully limit the current in the face of the phase jump fault. Specifically, taking the average sampling phase of the previous consecutive n sampling periods of the current sampling period as the comparison reference value for comparing with the sampling phase of the current sampling period can not only realize the real-time update of the comparison reference value, but also avoid the interference of accidental factors, realize the accurate identification of the phase jump and adjust the reference phase accordingly; the difference between the current real-time phase and the reference phase can characterize the phase jump situation, and superimposing the determined phase compensation angle on the phase given value used for phase control can effectively compensate for the phase jump at the grid connection point, improving the operation reliability, stability and safety of the grid-forming energy storage converter.

[0063] Based on the above embodiments, optionally, before determining the phase compensation angle according to the difference between the real-time phase and the reference phase, the method further includes: when the absolute value of the difference between the sampling phase of the current sampling period and the average sampling phase is less than or equal to the first preset phase difference, it is determined that no phase jump occurs at the grid connection point, and the sampling phase of the current sampling period is used as the reference phase.

[0064] When the absolute value of the difference between the sampling phase of the current sampling period and the average sampling phase is less than or equal to the first preset phase difference, it indicates that the phase change amount of the grid connection point is within the normal range, and it can be considered that there is no phase jump. In this case, the sampling phase of the current sampling period is directly used as the reference phase output. The sampling phase of the current sampling period can be considered to be consistent with the real-time phase. Then, the reference phase at this time is substantially consistent with the real-time phase, and the difference between the real-time phase and the reference phase is 0. Therefore, the phase compensation angle is 0, and the controller still controls the grid-forming energy storage converter according to the original phase given value. In this way, when there is no phase jump, the phase compensation angle is 0, and no phase jump compensation is performed on the grid connection point. The grid-forming energy storage converter can continue to operate and output normally, meeting the actual phase control requirements.

[0065] Figure 2 is a flowchart of a phase compensation control method for a grid-forming energy storage converter provided by an embodiment of the present invention. Refer to Figure 2 This phase compensation control method for the grid-forming energy storage converter may specifically include the following control links:

[0066] 1) Park transformation link: Based on the locally self-built phase angle θ0 that changes with the power frequency period, through Park transformation, the three-phase voltage v in the three-phase stationary coordinate system (i.e., abc coordinate system) pcc_abc is converted into the q-axis voltage v in the two-phase rotating coordinate system (i.e., dq coordinate system) q and the d-axis voltage v d .

[0067] This link is the specific implementation method for converting the three-phase voltage into the q-axis voltage and the d-axis voltage in the two-phase rotating coordinate system in S110. Specifically, the power frequency is the working frequency of the power grid in the grid-connected system where the grid-forming energy storage converter is located, for example, 50 Hz. Then, the self-built phase angle θ0 is a phase angle that changes sinusoidally at a frequency of 50 Hz. By generating a phase angle θ0 that changes with the power frequency period locally and providing it to the Park transformation link as a phase reference, and performing Park transformation on the three-phase voltage v of the grid connection point sampled in real time pcc_abc , the two-phase direct current quantities v d and v q in the self-built dq coordinate system can be finally obtained.In this embodiment, compared with directly providing the angular frequency of the power grid to the Park transformation link, by using the self-built phase angle θ0 that is stabilized at the power frequency and provided additionally, it can be ensured that the phase used in the Park transformation link is a stable phase that is not disturbed by the change of the operating state, which is beneficial to obtaining accurate real-time phase and reference phase in the subsequent processing link, and improving the accuracy and effect of phase jump compensation. Moreover, in this embodiment, there is no need to use a phase-locked loop to lock the phase and provide it to the Park transformation link, which can simplify the control process, save the computing power of the controller, and improve the real-time performance of phase control.

[0068] 2) Real-time phase calculation link: The two-phase direct current q-axis voltage v q and d-axis voltage v d obtained from the Park transformation link based on the locally self-built phase angle are used as the inputs of this real-time phase calculation link. Through the real-time phase calculation link, the real-time phase θ pcc of the grid connection point is obtained.

[0069] Among them, the real-time phase of the grid connection point can be calculated in real time according to the following formula: ; where θ pcc is the real-time phase, v d is the d-axis voltage, and v q is the q-axis voltage.

[0070] 3) PAJ (Phase Angle Jump) detection link: The two-phase direct current q-axis voltage v q and d-axis voltage v d obtained from the Park transformation link based on the locally self-built phase angle are used as the inputs of this PAJ detection link. The PAJ detection link samples the q-axis voltage v q and d-axis voltage v d at a preset sampling frequency, calculates the sampling phase of each sampling period, and outputs the reference phase θ base accordingly. The reference phase θ base is used to determine the phase compensation angle θ' cal .

[0071] Specifically, for the i-th sampling period, the sampling phase of the grid connection point in the i-th sampling period can be calculated according to the following formula, where i is a positive integer: ; where θ i is the sampling phase of the grid connection point in the i-th sampling period, v di is the d-axis voltage sampled in the i-th sampling period, and v qi is the q-axis voltage sampled in the i-th sampling period.

[0072] The process of obtaining the average sampling phase can be as follows: establish a storage queue that can store n elements; each time a new element is added, it is stored at the head of the storage queue, and the element at the end of the queue is deleted, and the remaining elements are all moved one position backward to update the storage queue. Among them, each element in the storage queue includes the sampling phase of a sampling period, and the storage queue is updated once every sampling period. The storage queue can be understood as a window that can store the sampling phases of consecutive n sampling periods sorted by time and slides in real time as the sampling period increases. In each sampling period, the average value of the elements in the storage queue before update can be obtained first as the average sampling phase for comparison with the sampling phase in this sampling period; after obtaining the comparison result between the sampling phase and the average sampling phase in this sampling period, the storage queue can be updated according to the sampling phase of this sampling period. Exemplarily, n = 10.

[0073] Among them, in each sampling period, the comparison between the current sampling phase and the average sampling phase is performed to determine whether the absolute value of the difference between the sampling phase of the current sampling period and the average value of the sampling phases of the n sampling periods before the current sampling period (i.e., the average sampling phase) is greater than the first preset phase difference; if so, it is determined that a phase jump has occurred, and the average sampling phase is output as the reference phase θ base , and the storage queue and the average sampling phase are updated; if not, it is determined that no phase jump has occurred, and the sampling phase of the current sampling period is output as the reference phase θ base , and the storage queue and the average sampling phase are updated.

[0074] Furthermore, the PAJ detection link can also output a jump depth identifier Severe, and the jump depth identifier Severe can characterize the phase jump degree of the grid connection point and is used to adjust the gain of the difference between the real-time phase θ pcc and the reference phase θ base .

[0075] Exemplarily, it can be set to enable the PAJ detection link after the startup process of the grid-forming PCS ends and runs into a steady state. In this way, it is equivalent to starting the algorithm of this link when the environment and conditions for the normal operation of the algorithm in this link are available, which is beneficial to improving the reliability of phase control.

[0076] 4) Compensation link: As shown by the dashed box in Figure 2 , the phase compensation angle θ' pcc can be calculated according to the difference between the real-time phase θ base and the reference phase θ cal .

[0077] Specifically, the compensation link can include: a subtractor link: subtracting the reference phase θ pcc from the real-time phase θ baseSubtract to obtain the phase difference θ cal This phase difference θ cal can be directly used as the phase compensation angle θ' cal or, after other processing, obtain the phase compensation angle θ' cal .

[0078] Furthermore, the compensation link may include: a gain link: the phase difference θ cal and the jump depth identifier Severe are used as the inputs of the gain link. The gain link adjusts the gain coefficient (denoted as k1) for the phase difference θ cal according to the jump depth identifier Severe. The calculated compensation angle value θ1 output by the gain link is: θ1 = k1 × θ cal . This calculated compensation angle value θ1 can be directly used as the phase compensation angle θ' cal or, after other processing, obtain the phase compensation angle θ' cal . With this setting, it is equivalent to being able to dynamically adjust the gain coefficient k1 according to the phase jump depth when a phase jump occurs. For example, k1 ≥ 1 can be set, and it is positively correlated with the phase jump depth. In this way, a larger gain coefficient k1 can be provided when the phase jump depth is larger, and thus a larger phase compensation angle θ' cal can be provided, so as to achieve phase jump compensation as soon as possible. Among them, the phase jump depth is, for example, the difference between the sampling phase of the current sampling period and the sampling phase of the previous sampling period.

[0079] Specifically, in the PAJ detection link, after determining that a phase jump occurs at the grid connection point and taking the average sampling phase as the reference phase, it further includes: determining the jump depth identifier Severe according to the difference between the sampling phase of the current sampling period and the sampling phase of the previous sampling period; determining the gain coefficient k1 according to the jump depth identifier Severe.

[0080] Correspondingly, in the compensation link, the phase compensation angle θ' pcc is determined according to the difference between the real-time phase θ base and the reference phase θ cal , including: determining the phase compensation angle θ' pcc according to the product of the difference between the real-time phase θ base and the reference phase θ cal and the gain coefficient k1.

[0081] Even further, the compensation link may also include: a limiting link: the calculated compensation angle value θ1 is used as the input of the limiting link. Through the limiting link, the calculated compensation angle value θ1 can be limited between ±π / 2 to form the phase compensation angle θ' cal . In this way, by limiting the phase compensation angle θ' calThe range not exceeding ±π / 2 can avoid overcompensation, prevent system instability caused by excessive phase compensation angle, and improve system reliability and stability.

[0082] Specifically, the phase compensation angle is determined according to the product of the difference between the real-time phase and the reference phase and the gain coefficient, including: calculating the product of the difference between the real-time phase θ pcc and the reference phase θ base and the gain coefficient k1 as the calculated compensation angle value θ1; if the calculated compensation angle value θ1 is between -π / 2 and π / 2, then the calculated compensation angle value θ1 is used as the phase compensation angle θ' cal ; if the calculated compensation angle value θ1 is less than -π / 2, then the phase compensation angle θ' cal is set to -π / 2; if the calculated compensation angle value θ1 is greater than π / 2, then the phase compensation angle θ' cal is set to π / 2.

[0083] The expression of the limiting link can be: .

[0084] In summary, the specific process of the compensation link can be: the subtractor link calculates the phase difference θ pcc between the real-time phase θ base and the reference phase θ cal ; the gain link determines the gain coefficient k1 according to the jump depth flag Severe, and then processes the phase difference θ cal to obtain the calculated compensation angle value θ1; the limiting link limits the calculated compensation angle value θ1 to obtain the final phase compensation angle θ' cal .

[0085] The above embodiments explain the overall process of the method. Next, the specific process of the PAJ detection link will be explained in detail.

[0086] Figure 3 is a schematic flowchart of a PAJ detection link provided by an embodiment of the present invention. Figure 3 Exemplarily, the processing process of the PAJ detection link in the i-th sampling period is given. The processing process of the PAJ detection link in any sampling period can refer to the processing process in the i-th sampling period and will not be elaborated here. Refer to Figure 3 , the processing process of the PAJ detection link in the i-th sampling period includes:

[0087] S210. Sample v di and v qi .

[0088] S220. Calculate θ di according to v qi and v i .

[0089] S230. Determine whether ∣θ i - θ i-1_mean ∣ is greater than a first preset phase difference? If so, execute S240; if not, execute S280.

[0090] Wherein, θ i-1_mean is the average sampling phase for comparison in the i-th sampling period, and is equal to the average value of the sampling phases of n consecutive sampling periods before and consecutive with the i-th sampling period.

[0091] S240. Output θ i-1_mean as θ base , and update θ i according to θ i_mean .

[0092] Wherein, this step is the operation when a phase jump is determined. θ i_mean is the average sampling phase for comparison in the (i + 1)-th sampling period, and is equal to the average value of the sampling phases of n consecutive sampling periods up to the i-th sampling period. Exemplarily, the step of outputting θ i-1_mean as θ base and the step of updating θ i according to θ i_mean can be carried out simultaneously or successively, and are not limited herein.

[0093] S250. Determine whether ∣θ i - θ i-1 ∣ is greater than a second preset phase difference? If so, execute S260; if not, execute S270.

[0094] Wherein, θ i-1 is the sampling phase in the (i - 1)-th sampling period.

[0095] Specifically, according to the difference between the sampling phase of the current sampling period and the sampling phase of the previous sampling period, determine the jump depth identifier, including: if the absolute value of the difference between the sampling phase of the current sampling period and the sampling phase of the previous sampling period is greater than the second preset phase difference, set the jump depth identifier to a first preset value; if the absolute value of the difference between the sampling phase of the current sampling period and the sampling phase of the previous sampling period is less than or equal to the second preset phase difference, set the jump depth identifier to a second preset value; the first preset value is different from the second preset value.

[0096] Correspondingly, determine the gain coefficient according to the jump depth identifier, including: if the jump depth identifier is the first preset value, set the gain coefficient to a value greater than 1; if the jump depth identifier is the second preset value, set the gain coefficient to 1.

[0097] Among them, the second preset phase difference can be set according to empirical values, the results of relevant phase jump experiments conducted in advance, or relevant data during the historical operation process, and specific limitations are not imposed here. When the absolute value of the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period is greater than the second preset phase difference, it can be considered that the phase jump depth exceeds the limit. At this time, increasing the gain coefficient is beneficial to quickly realizing the compensation of the phase jump. Exemplarily, when the jump depth identifier is the first preset value, the gain coefficient k1 can be set to satisfy: 1 < k1 ≤ 3; the value range of this gain coefficient k1 can also be set according to empirical values, the results of relevant phase jump experiments conducted in advance, or relevant data during the historical operation process, and specific limitations are not imposed here. Exemplarily, for example, the first preset value is 1 and the second preset value is 0.

[0098] In another implementation, determining the jump depth identifier according to the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period includes:

[0099] If the first condition is satisfied, set the jump depth identifier to the first preset value;

[0100] If the second condition is satisfied, set the jump depth identifier to the second preset value;

[0101] If neither the first condition nor the second condition is satisfied, control the value of the jump depth identifier to remain unchanged.

[0102] Among them, the first condition includes: in the first preset number of sampling periods up to the current sampling period, the absolute value of the difference between the sampling phase of each sampling period and the sampling phase of the previous sampling period is greater than the second preset phase difference, and the first preset number is a positive integer greater than 1. Among them, the above-mentioned first preset number of sampling periods can be consecutive first preset number of sampling periods including the current sampling period. The second condition includes: in the second preset number of sampling periods up to the current sampling period, the absolute value of the difference between the sampling phase of each sampling period and the sampling phase of the previous sampling period is less than or equal to the second preset phase difference, and the second preset number is a positive integer greater than 1. Among them, the above-mentioned second preset number of sampling periods can be consecutive second preset number of sampling periods including the current sampling period.

[0103] Such a setting is equivalent to providing an anti-mis-triggering function. When it is determined that the phase jump depth exceeds the limit in multiple consecutive sampling periods, the jump depth flag is set to the first preset value, which can effectively prevent a gain coefficient greater than 1 from being mis-triggered due to accidental disturbances; and when it is determined that the phase jump depth does not exceed the limit in multiple consecutive sampling periods, the jump depth flag is set to the second preset value to avoid the gain coefficient being prematurely reset to 1 due to accidental disturbances; and when in multiple consecutive sampling periods, the number of consecutive times the jump depth exceeds the limit does not exceed the first preset number, and the number of consecutive times it does not exceed the limit does not exceed the second preset number, it indicates that the judgment result may be fluctuated by accidental factors and cannot reliably represent the actual situation. At this time, controlling the jump depth flag to maintain the current value unchanged can avoid misprocessing of the gain due to disturbances. Exemplarily, both the above first preset number and the second preset number can be set according to actual needs, and the first preset number and the second preset number can be the same or different. Exemplarily, both the first preset number and the second preset number can be numbers between 2 and 5, such as 2 or 3.

[0104] S260, Severe = 1.

[0105] Exemplarily here, the first preset value is 1.

[0106] S270, Severe = 0.

[0107] Exemplarily here, the second preset value is 0.

[0108] S280, Output θ i As θ base , and update θ according to θ i Update θ i_mean .

[0109] Among them, this step is the operation when it is determined that there is no phase jump. Exemplarily, the step of outputting θ i As θ base And the step of updating θ according to θ i Update θ i_mean Can be carried out simultaneously or successively, and there is no limitation here.

[0110] This embodiment provides the processing flow of the PAJ detection link in the i-th sampling period through S210 - S280. It should be noted that the above process and specific steps are only for exemplary illustration, and in actual applications, the step order can be adjusted or steps can be added or subtracted according to needs. Exemplarily, before or after S280, a step of clearing the jump depth flag Severe can also be set. It should also be noted that after S260, S270, and S280, the processing flow of the next sampling period (i.e., the (i + 1)-th sampling period) can be entered.

[0111] In summary, the phase compensation control method for the grid-forming energy storage converter provided by the embodiments of the present invention is a phase jump adaptability control method for the grid-forming PCS based on real-time phase compensation control, which can enable the grid-forming PCS to achieve phase jump fault ride-through. The real-time phase compensation control on which this method is based specifically includes a Park transformation link based on locally self-built power frequency phase, a real-time phase calculation link, a PAJ detection link, and a compensation link. Specifically, through the Park transformation based on locally self-built power frequency phase, without relying on a phase-locked loop, the three-phase AC voltage v at the grid connection point is pcc_abc converted to two-phase direct current quantities v d and v q in the self-built dq coordinate system; the real-time phase θ pcc of the grid connection point is obtained through real-time phase calculation; the determination of the occurrence of phase jump and the determination of the phase jump depth are carried out through PAJ detection, and the reference phase θ base and the jump depth identifier Severe are obtained; the phase difference obtained by subtracting the real-time phase θ pcc from the reference phase θ base is amplified through a gain link, and finally the final phase compensation angle θ' cal is obtained through a limiting link. Therefore, the embodiments of the present invention make up for the lack of research on phase jump in the related technology of grid-forming PCS, can realize the rapid measurement and calculation of the phase jump angle, and realize the real-time compensation of the phase jump angle, avoiding the problem that the traditional fault ride-through strategy cannot completely limit the current in the face of phase jump faults. In addition, the embodiments of the present invention can avoid using additional sensors in practical applications, reducing the calculation amount and cost. The embodiments of the present invention also involve the detection and limiting of the phase jump depth on the basis of identifying the phase jump. Therefore, appropriate phase values can be compensated according to the phase jump depth, while ensuring that the compensation angle will not be too large to affect the system stability. It can be understood that the phase compensation control method provided by the embodiments of the present invention can be used in conjunction with control strategies such as phase control in the related technology to realize the grid connection control of the grid-forming PCS and improve the operation reliability of the grid-forming PCS.

[0112] The embodiments of the present invention also provide a phase compensation control device for a grid-forming energy storage converter, which is used to execute the phase compensation control method for the grid-forming energy storage converter provided by any embodiment of the present invention, has the corresponding functional modules and beneficial effects of the execution method, and each functional module can be implemented in the form of software and / or hardware as required. Figure 4 is a schematic structural diagram of a phase compensation control device for a grid-forming energy storage converter provided by an embodiment of the present invention. Refer to Figure 4 , the phase compensation control device for the grid-forming energy storage converter includes: a voltage acquisition module 310, a real-time phase calculation module 320, a phase jump detection module 330, and a compensation module 340.

[0113] Among them, the voltage acquisition module 310 is used to acquire the three-phase voltage of the grid connection point of the grid-forming energy storage converter and convert the three-phase voltage into the q-axis voltage and d-axis voltage in the two-phase rotating coordinate system. The real-time phase calculation module 320 is used to calculate the real-time phase of the grid connection point in real time according to the q-axis voltage and d-axis voltage. The phase jump detection module 330 is used to sample the q-axis voltage and d-axis voltage at a preset sampling frequency. In any sampling period, the sampling phase of the grid connection point in the sampling period is calculated according to the sampled q-axis voltage and d-axis voltage; when the absolute value of the difference between the sampling phase in the current sampling period and the average sampling phase is greater than the first preset phase difference, it is determined that a phase jump occurs at the grid connection point and the average sampling phase is used as the reference phase; among them, the average sampling phase is the average value of the sampling phases of consecutive n sampling periods before the current sampling period and consecutive with the current sampling period, and n is a positive integer greater than 1. The compensation module 340 is used to determine the phase compensation angle according to the difference between the real-time phase and the reference phase and superimpose the phase compensation angle on the phase given value of the grid-forming energy storage converter to compensate for the phase jump at the grid connection point.

[0114] Based on the above embodiments, optionally, the real-time phase calculation module 320 is specifically configured to: based on the phase angle that changes with the power frequency period built locally, through the Park transformation, convert the three-phase voltage into the q-axis voltage and d-axis voltage in the two-phase rotating coordinate system.

[0115] Further, the real-time phase calculation module 320 calculates the real-time phase of the grid connection point in real time according to the following formula: ; where θ pcc is the real-time phase, v d is the d-axis voltage, v q is the q-axis voltage.

[0116] Based on the above embodiments, optionally, for the i-th sampling period, the phase jump detection module 330 calculates the sampling phase of the grid connection point in the i-th sampling period according to the following formula, where i is a positive integer: ; where θ i is the sampling phase of the grid connection point in the i-th sampling period, v di is the d-axis voltage sampled in the i-th sampling period, v qi is the q-axis voltage sampled in the i-th sampling period. Exemplarily, n = 10.

[0117] Based on the above embodiments, optionally, before determining the phase compensation angle according to the difference between the real-time phase and the reference phase, the phase jump detection module 330 is further configured to: when the absolute value of the difference between the sampling phase in the current sampling period and the average sampling phase is less than or equal to the first preset phase difference, determine that there is no phase jump at the grid connection point and use the sampling phase in the current sampling period as the reference phase.

[0118] Based on the above embodiments, optionally, after determining that there is a phase jump at the grid connection point and using the average sampling phase as the reference phase, the phase jump detection module 330 is further configured to: determine a jump depth identifier according to the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period. The compensation module 340 is further configured to determine a gain coefficient according to the jump depth identifier. Correspondingly, the compensation module 340 is specifically configured to: determine the phase compensation angle according to the product of the difference between the real-time phase and the reference phase and the gain coefficient.

[0119] Based on the above embodiments, optionally, the process of the phase jump detection module 330 determining the jump depth identifier specifically includes: if the absolute value of the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period is greater than the second preset phase difference, set the jump depth identifier to the first preset value; if the absolute value of the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period is less than or equal to the second preset phase difference, set the jump depth identifier to the second preset value; the first preset value is different from the second preset value. Or, if in a continuous first preset number of sampling periods up to the current sampling period, the absolute value of the difference between the sampling phase of each sampling period and the sampling phase of the previous sampling period is greater than the second preset phase difference, set the jump depth identifier to the first preset value; if in a continuous second preset number of sampling periods up to the current sampling period, the absolute value of the difference between the sampling phase of each sampling period and the sampling phase of the previous sampling period is less than or equal to the second preset phase difference, set the jump depth identifier to the second preset value; the first preset number is a positive integer greater than 1, and the second preset number is a positive integer greater than 1.

[0120] Moreover, the process of the compensation module 340 determining the gain coefficient according to the jump depth identifier specifically includes: if the jump depth identifier is the first preset value, set the gain coefficient to a value greater than 1; if the jump depth identifier is the second preset value, set the gain coefficient to 1.

[0121] Based on the above embodiments, optionally, the compensation module 340 specifically includes: a subtractor, a gain control unit, and a clipping unit. The subtractor is configured to calculate the difference between the real-time phase and the reference phase. The gain control unit is configured to determine a gain coefficient according to the jump depth identifier, and calculate the product of the difference between the real-time phase and the reference phase and the gain coefficient as the compensation angle calculation value. The clipping unit is configured to: when the compensation angle calculation value is between -π / 2 and π / 2, use the compensation angle calculation value as the phase compensation angle; when the compensation angle calculation value is less than -π / 2, set the phase compensation angle equal to -π / 2; when the compensation angle calculation value is greater than π / 2, set the phase compensation angle equal to π / 2.

[0122] An embodiment of the present invention further provides a grid-connected system, including a grid-forming energy storage converter and a controller. The controller may integrate the phase compensation control device of the grid-forming energy storage converter provided in any embodiment of the present invention. The controller is configured to execute the phase compensation control method of the grid-forming energy storage converter provided in any embodiment of the present invention, and has corresponding beneficial effects.

[0123] Exemplarily, the grid-connected system may include: a grid-forming energy storage converter, a power grid, a load, and a controller; the grid-forming energy storage converter is connected to the power grid and the load through the grid connection point of the grid-forming energy storage converter, or in other words, the transmission lines of the grid-forming energy storage converter, the power grid, and the load meet at the grid connection point. Among them, the controller is connected to the grid-forming energy storage converter, and the controller is configured to control the phase of the grid connection point by using the phase compensation control method of the grid-forming energy storage converter provided in any embodiment of the present invention.

[0124] It should be understood that the various forms of the processes shown above can be used, re-ordered, added, or deleted steps. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is made herein.

[0125] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A phase compensation control method for a grid-forming energy storage converter, characterized in that Including: Obtain the three-phase voltages of the grid-connection point of the grid-forming energy storage converter, and convert the three-phase voltages into the q-axis voltage and d-axis voltage in a two-phase rotating coordinate system; Calculate the real-time phase of the grid-connection point in real time according to the q-axis voltage and the d-axis voltage; Sample the q-axis voltage and the d-axis voltage at a preset sampling frequency. In any sampling period, calculate the sampling phase of the grid-connection point in the sampling period according to the sampled q-axis voltage and d-axis voltage; when the absolute value of the difference between the sampling phase in the current sampling period and the average sampling phase is greater than a first preset phase difference, determine that the grid-connection point has a phase jump and use the average sampling phase as the reference phase; wherein, the average sampling phase is the average value of the sampling phases of consecutive n sampling periods before the current sampling period and consecutive with the current sampling period, and n is a positive integer greater than 1; Determine a phase compensation angle according to the difference between the real-time phase and the reference phase, and superimpose the phase compensation angle on the phase given value of the grid-forming energy storage converter to compensate for the phase jump of the grid-connection point.

2. The phase compensation control method of the network-forming energy storage converter according to claim 1, wherein Converting the three-phase voltages into the q-axis voltage and d-axis voltage in a two-phase rotating coordinate system includes: Based on the phase angle that changes with the power frequency period built locally, through Park transformation, convert the three-phase voltages into the q-axis voltage and d-axis voltage in a two-phase rotating coordinate system.

3. The phase compensation control method of the network-forming energy storage converter according to claim 1, characterized in that, Calculate the real-time phase of the grid-connection point in real time according to the following formula: ； where θ pcc is the real-time phase, v d is the d-axis voltage, v q is the q-axis voltage.

4. The phase compensation control method of the grid-forming energy storage converter according to claim 1, characterized in that For the i-th sampling period, calculate the sampling phase of the grid-connection point in the i-th sampling period according to the following formula, where i is a positive integer: ； where θ i is the sampling phase of the grid connection point in the i-th sampling period, v di is the d-axis voltage sampled in the i-th sampling period, v qi is the q-axis voltage sampled in the i-th sampling period.

5. The phase compensation control method of the network-forming energy storage converter according to claim 1, characterized in that, Before determining the phase compensation angle according to the difference between the real-time phase and the reference phase, it further includes: When the absolute value of the difference between the sampling phase in the current sampling period and the average sampling phase is less than or equal to the first preset phase difference, determine that the grid-connection point has not had a phase jump and use the sampling phase in the current sampling period as the reference phase.

6. The phase compensation control method of the network-forming energy storage converter according to claim 1, characterized in that, After determining that the grid-connection point has a phase jump and using the average sampling phase as the reference phase, it further includes: Determine a jump depth identifier according to the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period; Determine a gain coefficient according to the jump depth identifier; Correspondingly, determining the phase compensation angle according to the difference between the real-time phase and the reference phase includes: determining the phase compensation angle according to the product of the difference between the real-time phase and the reference phase and the gain coefficient.

7. The phase compensation control method of the network-forming energy storage converter according to claim 6, characterized in that, Determining a jump depth identifier according to the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period includes: If the absolute value of the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period is greater than a second preset phase difference, set the jump depth identifier to a first preset value; if the absolute value of the difference between the sampling phase in the current sampling period and the sampling phase in the previous sampling period is less than or equal to the second preset phase difference, set the jump depth identifier to a second preset value; the first preset value is different from the second preset value; Alternatively, if the first condition is met, set the jump depth identifier to a first preset value; if the second condition is met, set the jump depth identifier to a second preset value; if neither the first condition nor the second condition is met, control the value of the jump depth identifier to remain unchanged; wherein, the first condition includes: in the first preset number of sampling periods up to the current sampling period, the absolute value of the difference between the sampling phases of each sampling period and the sampling phase of the previous sampling period is greater than a second preset phase difference, and the first preset number is a positive integer greater than 1; the second condition includes: in the second preset number of sampling periods up to the current sampling period, the absolute value of the difference between the sampling phases of each sampling period and the sampling phase of the previous sampling period is less than or equal to the second preset phase difference, and the second preset number is a positive integer greater than 1; Determining a gain coefficient according to the jump depth identifier includes: If the jump depth identifier is the first preset value, set the gain coefficient to a value greater than 1; If the jump depth identifier is the second preset value, set the gain coefficient to 1.

8. The phase compensation control method of the network-forming energy storage converter according to claim 6, characterized in that Determining the phase compensation angle according to the product of the difference between the real-time phase and the reference phase and the gain coefficient includes: Calculating the product of the difference between the real-time phase and the reference phase and the gain coefficient as a compensation angle calculation value; If the compensation angle calculation value is between -π / 2 and π / 2, use the compensation angle calculation value as the phase compensation angle; If the compensation angle calculation value is less than -π / 2, set the phase compensation angle to -π / 2; If the compensation angle calculation value is greater than π / 2, set the phase compensation angle to π / 2.

9. A phase compensation control device for a grid-forming energy storage converter, characterized in that, Including: A voltage acquisition module for acquiring the three-phase voltage of the grid connection point of the grid-forming energy storage converter and converting the three-phase voltage into the q-axis voltage and d-axis voltage in a two-phase rotating coordinate system; A real-time phase calculation module for calculating the real-time phase of the grid connection point according to the q-axis voltage and the d-axis voltage in real time; A phase jump detection module for sampling the q-axis voltage and the d-axis voltage at a preset sampling frequency. In any sampling period, calculate the sampling phase of the grid connection point in the sampling period according to the sampled q-axis voltage and d-axis voltage; when the absolute value of the difference between the sampling phase in the current sampling period and the average sampling phase is greater than a first preset phase difference, determine that a phase jump occurs at the grid connection point and use the average sampling phase as the reference phase; wherein, the average sampling phase is the average value of the sampling phases of consecutive n sampling periods before the current sampling period and consecutive with the current sampling period, and n is a positive integer greater than 1; A compensation module for determining a phase compensation angle according to the difference between the real-time phase and the reference phase and adding the phase compensation angle to the phase given value of the grid-forming energy storage converter to compensate for the phase jump at the grid connection point.

10. A grid-connected system, characterized in that, Including: A grid-forming energy storage converter, a power grid, a load, and a controller; The grid-forming energy storage converter is connected to the power grid and the load through the grid connection point of the grid-forming energy storage converter; the controller is connected to the grid-forming energy storage converter, and the controller is used to control the phase of the grid connection point by using the phase compensation control method of the grid-forming energy storage converter described in any one of claims 1-8.

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