Phase compensation control method and device for grid-connected energy storage converter, and grid-connected system

Abstract

The present invention discloses a phase compensation control method and device for a grid-connected energy storage converter, and a grid-connected system, belonging to the field of grid-connected control technology. The method includes: obtaining the three-phase voltage of the grid-connected point and converting it into q-axis voltage and d-axis voltage; calculating the real-time phase of the grid-connected point in real time based on the dq two-axis voltage; sampling the q-axis voltage and d-axis voltage according to a preset sampling frequency, and calculating the sampling phase of the grid-connected point in each sampling cycle; when the absolute value of the difference between the sampling phase of the current sampling cycle and the average sampling phase is greater than a first preset phase difference, determining that a phase jump occurs at the grid-connected point and using the average sampling phase as a reference phase; the average sampling phase is the average value of the sampling phases of n consecutive sampling cycles that are located before the current sampling cycle and are continuous with the current sampling cycle; determining the phase compensation angle based on the difference between the real-time phase and the reference phase and adding it to the phase given value. The present invention can realize real-time measurement and compensation of phase jumps at the grid-connected point.

Description

Technical Field

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

[0002] In power systems, the occurrence and removal of short-circuit faults can alter the grid's topology, leading to voltage amplitude and phase jumps at the grid connection point of the power conversion system (PCS). Currently, conventional fault ride-through control strategies for grid-connected PCSs mostly consider only the impact of amplitude drop during a fault, failing to account for the fact that changes in the external grid topology can also cause voltage phase jumps at the grid connection point. This phase jump increases the instantaneous voltage differential between the grid connection point voltage and the converter port, causing converter overcurrent issues and presenting a challenge for converter grid-connected operation.

[0003] When a grid phase jump occurs, a grid-connected PCS using a conventional fault ride-through strategy experiences a rapid change in its internal potential amplitude through reactive voltage loop control. If the reactive power control capability is strong, the reactive output can quickly reach the required reference value. However, due to the influence of virtual inertia, the phase cannot change quickly, making it difficult for the active output to quickly reach the required reference value. Regarding current limiting, when a fault occurs, the equivalent internal potential amplitude decreases rapidly under the conventional fault ride-through strategy. However, due to the phase jump, a certain phase difference exists between the grid voltage and the internal potential, resulting in a significant voltage difference and the inability to eliminate the risk of overcurrent. Therefore, in the control process of a grid-connected PCS, real-time detection and compensation of the phase jump angle at the grid connection point are urgently needed. Summary of the Invention

[0004] The present invention provides a phase compensation control method and device for a grid-connected energy storage converter, and a grid-connected system to achieve real-time measurement and timely compensation of phase jumps at grid connection points, thereby improving the operational reliability of the grid-connected energy storage converter.

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

[0006] Obtaining the three-phase voltage of the grid-connected point of the grid-type energy storage converter, and converting the three-phase voltage into a q-axis voltage and a d-axis voltage in a two-phase rotating coordinate system;

[0007] Calculating the real-time phase of the grid connection 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 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.

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

[0021] Determine the transition depth identifier according to the difference between the sampling phase of the current sampling cycle and the sampling phase of the previous sampling cycle;

[0022] Determining a 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 transition depth identifier according to a difference between a sampling phase of a current sampling period and a sampling phase of a previous sampling period includes:

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

[0026] Alternatively, if the first condition is met, the jump depth identifier is set to a first preset value; if the second condition is met, the jump depth identifier is set to a second preset value; if both the first condition and the second condition are not met, the value of the jump depth identifier is controlled to remain unchanged; wherein the first condition includes: in a 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 a second preset phase difference, and the first preset number is a positive integer greater than 1; the second condition includes: in a 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 a gain coefficient according to the jump depth identifier includes:

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

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

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

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

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

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

[0036] A voltage acquisition module is used to acquire the three-phase voltage of the grid-connected point of the grid-type energy storage converter and convert the three-phase voltage into a q-axis voltage and a 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 based on 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, and in any sampling period, calculate the sampling phase of the grid-connected point in the sampling period 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, determine that a phase jump has occurred at the grid-connected point and use the average sampling phase as a reference phase; wherein the average sampling phase is the average of the sampling phases of n consecutive sampling periods that are located before and continuous with the current sampling period, where n is a positive integer greater than 1;

[0039] A compensation module is used to determine a phase compensation angle according to the difference between the real-time phase and the reference phase, and add the phase compensation angle to the phase given value of the grid-type energy storage converter to compensate for the phase jump of the grid connection point.

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

[0041] The phase compensation control method for a grid-type energy storage converter provided in an embodiment of the present invention can realize the rapid identification and measurement of phase jumps at the grid connection point, and realize real-time compensation of phase jumps, effectively avoiding the problem that the traditional fault ride-through strategy cannot completely limit the current in the face of a phase jump fault. Specifically, the average sampling phase of the previous n consecutive sampling cycles of the current sampling cycle is used as a comparison reference value for comparison with the sampling phase of the current sampling cycle, which can not only realize the real-time update of the comparison reference value, but also avoid the interference of occasional factors, realize accurate identification of phase jumps 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 the phase compensation angle determined thereby is superimposed on the phase given value used for phase control, which can effectively compensate for the phase jump of the grid connection point and improve the operational reliability, stability and safety of the grid-type energy storage converter.

[0042] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily 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 briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

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

[0046] Figure 3 This is a schematic diagram of a PAJ detection process provided by an embodiment of the present invention;

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

[0048] In order to enable those skilled in the art to better understand the solutions 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 drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0049] It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and the accompanying drawings are used to distinguish similar items and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, such that the embodiments of the present invention described herein can be implemented in sequences other than those illustrated or described herein. Furthermore, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions.

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

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

[0052] S110 , obtaining the three-phase voltage of the grid-connected point of the grid-type energy storage converter, and converting the three-phase voltage into a q-axis voltage and a d-axis voltage in a two-phase rotating coordinate system.

[0053] The grid connection point is the point where the grid-type energy storage converter is connected to the grid. The grid-type energy storage converter can be connected to the grid and the three-phase load through the grid connection point. Under grid-connected operation, the grid connection point of the grid-type energy storage converter has an AC three-phase voltage. Exemplarily, the acquired three-phase voltage can be converted from a three-phase stationary coordinate system to the q-axis (quadrature axis) voltage and d-axis (direct axis) voltage in a two-phase rotating coordinate system through a transformation process such as Park transformation. It is understandable that the steps of acquiring the three-phase voltage and performing the coordinate system conversion are performed in real time following the operation of the grid-type energy storage converter, so as to collect and analyze the electrical quantity-related characteristics and operating conditions of the grid connection point in real time.

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

[0055] 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-connected energy storage inverter operates, the three-phase voltage at the grid connection point is continuously updated, and the real-time phase is also updated accordingly. For example, at any point in time, the real-time phase can be calculated based on the inverse tangent function of the ratio of the q-axis voltage to the d-axis voltage at that point in time.

[0056] S130. Sample the q-axis voltage and the 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 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, determine that a phase jump occurs at the grid connection point and use the average sampling phase as a reference phase.

[0057] The average sampling phase is the average of the sampling phases of n consecutive sampling cycles preceding and following the current sampling cycle, where n is a positive integer greater than 1. It is understood that the calculation process for the sampling phase of each sampling cycle continues as the grid-type energy storage converter operates, and the sampling cycles can be sequentially sorted in chronological order. The average sampling phase is also a variable that changes as the grid-type energy storage converter operates, rather than being a fixed value. The average sampling phase is recalculated and updated with each sampling cycle. For any sampling cycle, the average sampling phase used for comparison with the sampling phase of that sampling cycle is the average of the sampling phases of the n sampling cycles preceding that sampling cycle. For example, if the current sampling cycle is the jth sampling cycle during the operation of the grid-type 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 cycle is the average of the sampling phases of the jnth to j-1th sampling cycles. 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 of the grid connection point exceeds the normal range, which can be considered as a phase jump. 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 greater than 800 Hz, specifically 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 consistent with the calculation method of the real-time phase to avoid phase errors caused by different calculation methods. The first preset phase difference can be set based on empirical values ​​or pre-conducted phase jump related experimental results or relevant data in historical operation processes, and is not specifically limited here.

[0059] In this step, by comparing the sampling phase of the current sampling period with the average of the sampling phases of the previous n sampling periods to determine whether a phase jump occurs, compared to only comparing with the sampling phase of the previous sampling period, the influence of accidental factors can be avoided, and the misjudgment of phase jump can be avoided. Among them, the specific value of n can be selected according to actual needs, for example, it can be set in combination with the change of the grid connection point phase under ideal conditions and the value of the preset sampling frequency. Specifically, the most appropriate n value can be selected through simulation / experimentation. For example, 5≤n≤15 is used to avoid the situation where the n value is too small, causing accidental disturbances to affect the judgment result of the phase jump, and to avoid the situation where the n value is too large, causing the judgment time interval to be too long, resulting in the normal phase change being identified as a phase jump.

[0060] S140 , determining a phase compensation angle according to a difference between the real-time phase and the reference phase, and adding the phase compensation angle to a phase set value of the grid-connected energy storage converter to compensate for a phase jump at the grid connection point.

[0061] The difference between the real-time phase and the reference phase represents the phase jump at the grid connection point. In practical applications, this difference can be directly determined as the phase compensation angle, or it can be processed by gain or other means to form the phase compensation angle. The phase setpoint of a grid-connected 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 of the grid connection point. Therefore, by adjusting the phase setpoint based on the phase compensation angle, effective compensation for phase jumps can be achieved, and the phase of the grid connection point can be promptly adjusted back to the normal value.

[0062] In summary, the phase compensation control method for the grid-type energy storage converter provided by the embodiment of the present invention can realize the rapid identification and measurement of the phase jump of the grid-connected point, and realize the real-time compensation of the phase jump, effectively avoiding the problem that the traditional fault crossing strategy cannot completely limit the current in the face of a phase jump fault. Specifically, the average sampling phase of the previous n consecutive sampling cycles of the current sampling cycle is used as a comparison reference value for comparison with the sampling phase of the current sampling cycle, which can not only realize the real-time update of the comparison reference value, but also avoid the interference of occasional 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 the phase compensation angle determined thereby is superimposed on the phase given value used for phase control, which can effectively compensate for the phase jump of the grid-connected point and improve the operating reliability, stability and safety of the grid-type energy storage converter.

[0063] Based on the above embodiments, optionally, before determining the phase compensation angle based on the difference between the real-time phase and the reference phase, the method also 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, determining that no phase jump occurs at the grid connection point and using the sampling phase of the current sampling period as the reference phase.

[0064] Among them, 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 of the grid-connected point is within the normal range, and it can be considered that no phase jump occurs. In this case, the sampling phase of the current sampling period is directly output as the reference phase, and 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 essentially 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-type energy storage inverter according to the original phase given value. In this way, in the absence of a phase jump, the phase compensation angle is 0, and the grid-connected point is not compensated for the phase jump. The grid-type energy storage inverter can continue to operate and output normally, meeting the actual phase control requirements.

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

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

[0067] This link is a specific implementation method for converting the three-phase voltage into the q-axis voltage and d-axis voltage in the two-phase rotating coordinate system in S110. Specifically, the power frequency is the operating frequency of the grid in the grid-connected system where the grid-type energy storage converter is located, for example, 50Hz. Then, the self-built phase angle θ0 is a phase angle that changes sinusoidally at a frequency of 50Hz. By locally generating a phase angle θ0 that changes with the power frequency cycle and providing it to the Park transformation link as a phase reference, and based on the phase angle θ0, the real-time sampled grid-connected point three-phase voltage v pcc_abc Perform Park transformation and finally get the two-phase DC quantity v in the self-built dq coordinate system d and v qIn this embodiment, compared to directly providing the angular frequency of the power grid to the Park transformation link, by adopting the additional self-built phase angle θ0 that is stable at the power frequency, it is possible to ensure that the phase used in the Park transformation link is a stable phase that is not disturbed by changes in the operating state. This is conducive to obtaining accurate real-time phase and reference phase in subsequent processing links, and improving the accuracy and effect of phase jump compensation. In addition, 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 controller computing power, and improve the real-time performance of phase control.

[0068] 2) Real-time phase calculation link: The two-phase DC q-axis voltage v is obtained by the Park transformation link based on the local self-built phase angle q and d-axis voltage v d As the input of the real-time phase calculation link, the real-time phase θ of the grid connection point is obtained through the real-time phase calculation link. pcc .

[0069] 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, v q is the q-axis voltage.

[0070] 3) PAJ (Phase Angle Jump) detection link: The two-phase DC q-axis voltage v is obtained by the Park transformation link based on the locally built phase angle q and d-axis voltage v d As the input of the PAJ detection link, the PAJ detection link samples the q-axis voltage v according to the preset sampling frequency q and d-axis voltage v d , and calculate the sampling phase of each sampling period, and output the reference phase θ accordingly base , reference phase θ base 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-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.

[0072] The process of obtaining the average sampling phase can be: establishing a storage queue that can store n elements; each time an 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 moved back one position, so as to realize the update of the storage queue. Each element in the storage queue includes the sampling phase of a sampling period, and the storage queue is updated once after each sampling period. The storage queue can be understood as a window that can store the sampling phases of n consecutive sampling periods sorted by time and slide in real time with the increase of the sampling period. In each sampling period, the average value of each element in the storage queue before the update can be obtained as the average sampling phase to be compared with the sampling phase in the sampling period; after obtaining the comparison result of the sampling phase in the sampling period and the average sampling phase, the storage queue can be updated according to the sampling phase of the sampling period. Exemplarily, n=10.

[0073] In each sampling period, the current sampling phase is compared with the average sampling phase 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 update the storage queue and average sampling phase; if not, it is determined that no phase jump occurs, and the sampling phase of the current sampling cycle is output as the reference phase θ base , and update the storage queue and average sampling phase.

[0074] Furthermore, the PAJ detection link can also output the jump depth mark Severe, which can characterize the phase jump degree of the grid point and be used to adjust the real-time phase θ pcc With reference phase θ base The gain of the difference.

[0075] For example, the PAJ detection process can be enabled after the meshed PCS startup process is complete and the system enters a steady state. This is equivalent to enabling the algorithm in this process only when the environment and conditions are such that the algorithm in this process can function normally, which helps improve the reliability of phase control.

[0076] 4) Compensation: See Figure 2 As shown in the dotted box in the figure, the real-time phase θ pcc With reference phase θ base The difference between the phase compensation angle θ' is calculated cal .

[0077] Specifically, the compensation link may include: subtractor link: converting the real-time phase θ pcc With reference phase θ baseSubtract the phase difference θ cal The phase difference θ cal Can be directly used as the phase compensation angle θ' cal , or after other processing, the phase compensation angle θ' cal .

[0078] Furthermore, the compensation link may include: Gain link: the phase difference value θ cal The jump depth mark Severe is used as the input of the gain link. The gain link adjusts the phase difference value θ according to the jump depth mark Severe. cal The gain coefficient (denoted as k1); the compensation angle calculation value θ1 output by the gain link is: θ1=k1×θ cal The calculated compensation angle θ1 can be directly used as the phase compensation angle θ' cal , or after other processing, the phase compensation angle θ' cal This setting 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 can be set to ≥ 1 and 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 large, thereby providing a larger phase compensation angle θ' cal , thereby achieving phase jump compensation as quickly as possible. The phase jump depth is, for example, the difference between the sampling phase of the current sampling cycle and the sampling phase of the previous sampling cycle.

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

[0080] Accordingly, in the compensation link, according to the real-time phase θ pcc With reference phase θ base The difference between the two determines the phase compensation angle θ' cal , including: according to the real-time phase θ pcc With reference phase θ base The product of the difference and the gain coefficient k1 determines the phase compensation angle θ' cal .

[0081] Furthermore, the compensation link may also include: a limiting link: the compensation angle calculated value θ1 is used as the input of the limiting link, and the compensation angle calculated value θ1 can be limited to ±π / 2 through the limiting link to form the phase compensation angle θ' cal Thus, by limiting the phase compensation angle θ' calBy not exceeding the range of ±π / 2, over-compensation can be avoided, as can system instability caused by excessive phase compensation angles, thereby improving system reliability and stability.

[0082] Specifically, the phase compensation angle is determined based on the product of the difference between the real-time phase and the reference phase and the gain coefficient, including: calculating the real-time phase θ pcc With reference phase θ base The product of the difference and the gain coefficient k1 is used as the compensation angle calculation value θ1; if the compensation angle calculation value θ1 is between -π / 2 and π / 2, the compensation angle calculation value θ1 is used as the phase compensation angle θ' cal If the calculated compensation angle θ1 is less than -π / 2, the phase compensation angle θ' is set. cal = -π / 2; if the calculated compensation angle θ1 is greater than π / 2, then set the phase compensation angle θ' cal Equal 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 is used to calculate the real-time phase θ pcc With reference phase θ base Get the phase difference θ cal ; The gain link determines the gain coefficient k1 according to the jump depth mark Severe, and then the phase difference value θ cal The compensation angle calculation value θ1 is obtained by processing; the limiting link limits the compensation angle calculation value θ1 to obtain the final phase compensation angle θ' cal .

[0085] The above embodiments explain the overall process of the method. The specific process of the PAJ detection link is explained in detail below.

[0086] Figure 3 This is a flow chart of a PAJ detection process provided by an embodiment of the present invention. Figure 3 The processing flow of the PAJ detection link in the i-th sampling cycle is given as an example. The processing flow of the PAJ detection link in any sampling cycle can refer to the processing flow in the i-th sampling cycle and will not be repeated here. Figure 3 ,The processing process of the PAJ detection link in the ith sampling cycle includes:

[0087] S210, sampling v di and v qi .

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

[0089] S230, judgment |θ i -θ i-1_mean |>First Preset Phase Difference? If yes, execute S240; if no, execute S280.

[0090] Among them, θ i-1_mean is the average sampling phase used for comparison in the i-th sampling period, which is equal to the average of the sampling phases of n consecutive sampling periods that are located before the i-th sampling period and are continuous with the i-th sampling period.

[0091] S240, output θ i-1_mean As θ base , and according to θ i Update θ i_mean .

[0092] This step is to determine the operation when a phase jump occurs. i_mean is the average sampling phase used for comparison in the i+1th sampling period, which is equal to the average sampling phase of the n consecutive sampling periods ending at the i-th sampling period. i-1_mean As θ base The steps and according to θ i Update θ i_mean The steps can be performed simultaneously or sequentially, which is not limited here.

[0093] S250, judgment |θ i -θ i-1 |>Second preset phase difference? If yes, execute S260; if no, execute S270.

[0094] Among them, θ i-1 is the sampling phase in the i-1th sampling period.

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

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

[0097] Among them, the second preset phase difference can be set according to the empirical value or the results of the phase jump related experiments conducted in advance or the relevant data in the historical operation process, and is not specifically limited here. When 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, it can be considered that the phase jump depth exceeds the limit. At this time, the gain coefficient is increased, which is conducive to compensating the phase jump as soon as possible. Exemplarily, when the jump depth is identified as the first preset value, the gain coefficient k1 can be set to satisfy: 1<k1≤3; the value range of the gain coefficient k1 can also be set according to the empirical value or the results of the phase jump related experiments conducted in advance or the relevant data in the historical operation process, and is not specifically limited here. Exemplarily, for example, the first preset value is 1 and the second preset value is 0.

[0098] In another embodiment, determining the transition depth identifier according to the difference between the sampling phase of the current sampling period and the sampling phase of the previous sampling period includes:

[0099] If the first condition is met, setting the jump depth flag to a first preset value;

[0100] If the second condition is met, setting the jump depth flag to a second preset value;

[0101] If both the first condition and the second condition are not met, the value of the control jump depth flag remains unchanged.

[0102] The first condition includes: in a 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 first preset number of sampling periods may be a first preset number of consecutive sampling periods including the current sampling period. The second condition includes: in a 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. The second preset number of sampling periods may be a second preset number of consecutive sampling periods including the current sampling period.

[0103] This setting is equivalent to providing a false trigger prevention function. When the phase jump depth is determined to be beyond the limit for multiple consecutive sampling periods, the jump depth identifier is set to the first preset value, which can effectively prevent the gain coefficient greater than 1 from being falsely triggered due to accidental disturbances; and when the phase jump depth is determined to be within the limit for multiple consecutive sampling periods, the jump depth identifier is set to the second preset value to avoid the gain coefficient being prematurely reset to 1 due to accidental disturbances; and when the jump depth is continuously exceeded for multiple consecutive sampling periods, the number of times the jump depth continuously exceeds the limit does not exceed the first preset number, and the number of times it is continuously within the limit does not exceed the second preset number, indicating that the judgment result may be affected by accidental factors and fluctuate, and cannot reliably represent the actual situation. In this case, the jump depth identifier is controlled to maintain the current value unchanged, which can avoid gain mishandling caused by disturbances. Exemplarily, the above-mentioned first preset number and 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, the first preset number and the second preset number can both be numbers between 2 and 5, for example, both are 2 or both are 3.

[0104] S260, Severe=1.

[0105] Here, for example, the first preset value is 1.

[0106] S270, Severe=0.

[0107] Here, illustratively, the second preset value is 0.

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

[0109] This step is to determine if there is no phase jump. i As θ base The steps and according to θ i Update θ i_mean The steps can be performed simultaneously or sequentially, which is not limited here.

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

[0111] In summary, the phase compensation control method for the grid-type energy storage converter provided by the embodiment of the present invention is a grid-type PCS phase jump adaptive control method based on real-time phase compensation control, which can enable the grid-type PCS to achieve phase jump fault traversal. The real-time phase compensation control based on this method specifically includes a Park transformation link based on the local 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 the local self-built power frequency phase, without the help of a phase-locked loop, the AC three-phase voltage v pcc_abc Convert to the two-phase DC quantity v in the self-built dq coordinate system d and v q ; The real-time phase θ of the grid connection point is obtained through real-time phase calculation pcc ; The occurrence of phase jump and the depth of phase jump are determined by PAJ detection and the reference phase θ is obtained. base and jump depth mark Severe; real-time phase θ pcc With reference phase θ base The phase difference obtained by subtraction is then amplified by the gain link, and finally the final phase compensation angle θ' is obtained by the limiting link. cal . Therefore, the embodiment of the present invention makes up for the lack of research on phase jumps in the related art for meshed PCS, can realize rapid measurement and calculation of the phase jump angle, and realize 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 a phase jump fault. In addition, the embodiment of the present invention can avoid the use of additional sensors in practical applications, reducing the amount of calculation and cost. The embodiment of the present invention, on the basis of identifying the phase jump, also involves the detection and limiting of the phase jump depth, so that it can compensate for the appropriate phase value according to the phase jump depth, while ensuring that the compensation angle will not be too large to affect the stability of the system. It can be understood that the phase compensation control method provided by the embodiment of the present invention can be used in conjunction with control strategies such as phase control in the related art to realize the grid-connected control of the meshed PCS and improve the operational reliability of the meshed PCS.

[0112] An embodiment of the present invention also provides a phase compensation control device for a grid-type energy storage inverter, which is used to execute the phase compensation control method for a grid-type energy storage inverter provided by any embodiment of the present invention, and has functional modules and beneficial effects corresponding to the execution method, and each functional module can be implemented in software and / or hardware form as needed. Figure 4 This is a schematic diagram of the structure of a phase compensation control device for a grid-type energy storage converter provided by an embodiment of the present invention. Figure 4 The phase compensation control device of the grid-type 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] The voltage acquisition module 310 is configured to acquire the three-phase voltage at the grid-connected point of the grid-type 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. The real-time phase calculation module 320 is configured to calculate the real-time phase of the grid-connected point based on the q-axis voltage and the d-axis voltage. The phase jump detection module 330 is configured to sample the q-axis voltage and the d-axis voltage at a preset sampling frequency. In any sampling cycle, the sampling phase of the grid-connected point 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 cycle and the average sampling phase is greater than a first preset phase difference, the grid-connected point is determined to have experienced a phase jump and the average sampling phase is used as the reference phase. The average sampling phase is the average of the sampling phases of n consecutive sampling cycles preceding and following the current sampling cycle, where n is a positive integer greater than 1. The compensation module 340 is configured to determine a phase compensation angle based on the difference between the real-time phase and the reference phase, and add the phase compensation angle to the phase set value of the grid-type energy storage converter to compensate for the phase jump of the grid-connected point.

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

[0115] Furthermore, 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-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. For example, n=10.

[0117] On the basis of the above-mentioned embodiments, optionally, before determining the phase compensation angle based on the difference between the real-time phase and the reference phase, the phase jump detection module 330 is also used to: 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, determine that no phase jump occurs at the grid connection point and use the sampling phase of the current sampling period as the reference phase.

[0118] Based on the above embodiments, optionally, after determining that a phase jump has occurred at the grid connection point and using the average sampling phase as a reference phase, the phase jump detection module 330 is further configured to determine a phase jump depth identifier based on the difference between the sampling phase of the current sampling period and the sampling phase of the previous sampling period. The compensation module 340 is further configured to determine a gain coefficient based on the phase jump depth identifier. Accordingly, the compensation module 340 is specifically configured to determine a phase compensation angle based on 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 determining the jump depth identifier by the phase jump detection module 330 specifically includes: 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, setting the jump depth identifier to the 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, setting the jump depth identifier to the second preset value; the first preset value and the second preset value are different. Alternatively, if the absolute value of the difference between the sampling phase of each sampling period and the sampling phase of the previous sampling period in a first preset number of consecutive sampling periods ending at the current sampling period is greater than the second preset phase difference, setting the jump depth identifier to the first preset value; if the absolute value of the difference between the sampling phase of each sampling period and the sampling phase of the previous sampling period in a second preset number of consecutive sampling periods ending at the current sampling period is less than or equal to the second preset phase difference, setting 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] Furthermore, 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 a first preset value, setting the gain coefficient to a value greater than 1; if the jump depth identifier is a second preset value, setting the gain coefficient to 1.

[0121] Based on the above embodiments, the compensation module 340 may optionally include a subtractor, a gain control unit, and a limiting unit. The subtractor is used to calculate the difference between the real-time phase and the reference phase. The gain control unit is used to determine the gain coefficient based on 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 limiting unit is used 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 also provides a grid-connected system, including a grid-type energy storage inverter and a controller. The controller can integrate the phase compensation control device of the grid-type energy storage inverter provided by any embodiment of the present invention. The controller is used to execute the phase compensation control method of the grid-type energy storage inverter provided by any embodiment of the present invention, and has corresponding beneficial effects.

[0123] Exemplarily, a grid-connected system may include: a grid-connected energy storage converter, a power grid, a load, and a controller; the grid-connected energy storage converter connects the power grid and the load via the grid-connected point of the grid-connected energy storage converter, or in other words, the transmission lines of the grid-connected energy storage converter, the power grid, and the load intersect at the grid-connected point. The controller is connected to the grid-connected energy storage converter and is configured to control the phase of the grid-connected point using the phase compensation control method for the grid-connected 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 to reorder, add, or delete steps. For example, the steps described in the present invention can be performed 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. This is not limited herein.

[0125] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A phase compensation control method for a grid-type energy storage converter, characterized in that: include: Obtaining the three-phase voltage of the grid-connected point of the grid-type energy storage converter, and converting the three-phase voltage into a q-axis voltage and a d-axis voltage in a two-phase rotating coordinate system; Calculating the real-time phase of the grid connection point in real time according to the q-axis voltage and the d-axis voltage; 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; 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.

2. The phase compensation control method of the grid-type energy storage converter according to claim 1, characterized in that: Converting the three-phase voltage into a q-axis voltage and a d-axis voltage in a two-phase rotating coordinate system includes: 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.

3. The phase compensation control method of the grid-type energy storage converter according to claim 1, characterized in that: The real-time phase of the grid connection point is calculated in real time according to the following formula: ； Among them, 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-type energy storage converter according to claim 1, characterized in that: 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: ； 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.

5. The phase compensation control method of the grid-type 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, 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.

6. The phase compensation control method of the grid-type energy storage converter according to claim 1, characterized in that: After determining that a phase jump occurs at the grid connection point and using the average sampling phase as a reference phase, the method further includes: Determine the transition depth identifier according to the difference between the sampling phase of the current sampling cycle and the sampling phase of the previous sampling cycle; Determining 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 grid-type energy storage converter according to claim 6, characterized in that: Determining a transition depth identifier based on a difference between a sampling phase of a current sampling period and a sampling phase of a previous sampling period includes: If the absolute value of the difference between the sampling phase of the current sampling cycle and the sampling phase of the previous sampling cycle is greater than the second preset phase difference, the jump depth identifier is set to the first preset value; if the absolute value of the difference between the sampling phase of the current sampling cycle and the sampling phase of the previous sampling cycle is less than or equal to the second preset phase difference, the jump depth identifier is set to the second preset value; the first preset value is different from the second preset value; Alternatively, if the first condition is met, the jump depth identifier is set to a first preset value; if the second condition is met, the jump depth identifier is set to a second preset value; if both the first condition and the second condition are not met, the value of the jump depth identifier is controlled to remain unchanged; wherein the first condition includes: in a 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 a second preset phase difference, and the first preset number is a positive integer greater than 1; the second condition includes: in a 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; Determining a gain coefficient according to the jump depth identifier includes: If the jump depth identifier is the first preset value, setting the gain coefficient to a value greater than 1; If the jump depth identifier is the second preset value, the gain coefficient is set to 1.

8. The phase compensation control method for a grid-type 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 calculated compensation angle value is between -π / 2 and π / 2, the calculated compensation angle value is used as the phase compensation angle; If the calculated compensation angle value is less than -π / 2, then the phase compensation angle is set to be equal to -π / 2; If the calculated compensation angle value is greater than π / 2, the phase compensation angle is set equal to π / 2.

9. A phase compensation control device for a grid-type energy storage converter, characterized in that: include: A voltage acquisition module is used to acquire the three-phase voltage of the grid-connected point of the grid-type energy storage converter and convert the three-phase voltage into a q-axis voltage and a d-axis voltage in a two-phase rotating coordinate system; A real-time phase calculation module, configured to calculate the real-time phase of the grid connection point in real time based on the q-axis voltage and the d-axis voltage; a phase jump detection module, configured to sample the q-axis voltage and the d-axis voltage at a preset sampling frequency, and in any sampling period, calculate the sampling phase of the grid-connected point in the sampling period 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, determine that a phase jump has occurred at the grid-connected point and use the average sampling phase as a reference phase; wherein the average sampling phase is the average of the sampling phases of n consecutive sampling periods that are located before and continuous with the current sampling period, where n is a positive integer greater than 1; A compensation module is used to determine a phase compensation angle according to the difference between the real-time phase and the reference phase, and add the phase compensation angle to the phase given value of the grid-type energy storage converter to compensate for the phase jump of the grid connection point.

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

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