A power current reshaping method and device for a hybrid system of grid-connected and grid-forming converters under power grid fault conditions

Abstract

The present application relates to the field of new energy power generation technology, and specifically provides a power current remodeling method and device for a grid-following type and grid-forming type converter hybrid system under grid fault conditions, comprising: using steady-state power angles of the grid-following type and grid-forming type converters under normal conditions to iteratively solve a balance point equation of the grid-following type and grid-forming type converter hybrid system during a fault, to obtain current phase angles of each grid-following type converter and output voltages of each grid-forming type converter; and adjusting active / reactive current reference values of the grid-following type converters and active power reference values of the grid-forming type converters based on the steady-state power angles of the grid-following type and grid-forming type converters, the current phase angles of each grid-following type converter, and the output voltages of each grid-forming type converter. The technical solution provided by the present application adjusts the control reference values of each converter adaptively, so that the power angles of each converter remain approximately unchanged before and after a grid fault, thereby improving the transient stable operation capability of the hybrid system.

Description

Technical Field

[0001] This invention relates to the field of new energy power generation technology, specifically to a power current reshaping method and apparatus for a hybrid system of grid-connected and grid-connected converters under grid fault conditions. Background Technology Grid-connected converters offer advantages such as high power quality and fast response speed under strong grid conditions, but are prone to oscillation and instability under weak grid conditions. In contrast, grid-connected converters can maintain stable operation under weak grid conditions, but are more susceptible to instability under strong grid conditions. Considering the complementary steady-state operation characteristics of the two types of converters under different grid intensities, a hybrid system can be constructed to adapt to a wide range of grid intensity variations. However, during grid faults, transient interactions between multiple converters can easily lead to cascading instability, potentially triggering large-scale grid disconnection accidents.

[0002] To address the aforementioned issues, it is necessary to propose a power and current reshaping method for a hybrid system of grid-connected and grid-connected converters under grid fault conditions. This method adaptively adjusts the current reference value of the grid-connected converter and the active power reference value of the grid-connected converter based on the degree of grid fault, thereby effectively suppressing the transient instability risk of the hybrid system. Summary of the Invention

[0003] To overcome the above-mentioned defects, this invention proposes a power current reshaping method and device for a hybrid system of grid-connected and grid-connected converters under grid fault conditions.

[0004] Firstly, a power current reshaping method is provided for a hybrid system of grid-connected and grid-connected converters under grid fault conditions. The power current reshaping method for this hybrid system includes: The equilibrium point equations of the hybrid system of grid-connected and grid-connected converters under normal operating conditions are solved iteratively to obtain the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions. Based on the steady-state power angles of the grid-type and grid-type converters under normal operating conditions, the equilibrium point equations of the hybrid system of grid-type and grid-type converters during the fault period are iteratively solved to obtain the current phase angles of each grid-type converter and the output voltages of each grid-type converter during the fault period. Based on the steady-state power angle of the grid-type and grid-type converters, the current phase angle of each grid-type converter, and the output voltage of each grid-type converter, the active / reactive current reference values ​​of the grid-type converter and the active power reference values ​​of the grid-type converter are adjusted.

[0005] Preferably, the equilibrium point equation for the hybrid system of grid-connected and grid-connected converters under normal operating conditions is as follows:

[0006]

[0007] In the above formula, let k∈[1,m], l ∈[1, n], where m is the total number of grid-connected converters and n is the total number of grid-connected converters. This is the input vector for the equilibrium point equations of a hybrid system of grid-type and grid-type converters under normal operating conditions. For the power angle of the k-th grid converter, For the first l The power angle of a grid-type converter For the first l Output voltage of a grid-type converter It is the transpose symbol. This is the output vector of the equilibrium point equations for a hybrid system of grid-type and grid-type converters under normal operating conditions. The voltage equation for the k-th grid converter is... For the first l The active power equation for a grid-type converter. For the first l The reactive power equations for a grid-type converter.

[0008] Furthermore, the voltage equation for the k-th grid converter is as follows:

[0009] The first l The active power equation for a grid-type converter is as follows:

[0010] The first l The reactive power equation for a grid-type converter is as follows:

[0011] In the above formula, Let x be the magnitude of the self-coupling impedance coefficient of the k-th grid converter. Let be the output current of the k-th grid converter. The phase angle is the self-coupling impedance coefficient of the k-th grid converter. Let the current phase angle be the k-th grid converter. This represents the amplitude of the mutual coupling coefficient between the power grid and the grid-connected converter. This is the three-phase grid voltage. The phase angle is the mutual coupling coefficient between the power grid and the grid-connected converter. To match the amplitude of the port mutual coupling coefficient of the grid converter, Let i be the output current of the i-th grid converter. To match the phase angle of the port mutual coupling coefficient of the grid converter, Let be the power angle difference between the i-th grid converter and the k-th grid converter. Let i be the current phase angle of the i-th grid converter. For the first j The amplitude of the port mutual coupling coefficient between the individual grid-type converter and the grid-type converter. For the first j Output voltage of a grid-type converter For the first j The phase angle of the mutual coupling coefficient between the ports of the individual grid-type converter and the grid-type converter. For the first j The power angle of a grid-type converter This is a reference value for active power. This represents the amplitude of the mutual coupling coefficient between the power grid and the grid-connected converter. The phase angle is the mutual coupling coefficient between the power grid and the grid-connected converter. For the first l Equivalent conductance of a grid-type converter For the first j The amplitude of the port mutual coupling coefficient of a grid-type converter. For the first j Output voltage of a grid-type converter For the first l The grid-type converter and the first j The power angle difference of a grid-type converter For the first j The phase angle of the port mutual coupling coefficient of the grid-type converter. The amplitude of the mutual coupling coefficient between the grid converter and the grid converter port. The phase angle of the mutual coupling coefficient between the grid converter and the port of the grid converter is... For the first l The reactive power droop factor of a grid-type converter This is a reference value for reactive power. For the first l The equivalent susceptance of a grid-type converter V 0 represents the rated voltage. Let be the power angle of the i-th grid converter.

[0012] Furthermore, the iterative solution of the equilibrium point equations for the hybrid system of grid-connected and grid-connected converters under normal operating conditions to obtain the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions includes: Step a: Initialize the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters under normal operating conditions; Step b: Substitute the output vector of the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions into the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions, and calculate the output vector of the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions. Step c: Construct the Jacobian matrix of the current hybrid system of grid-type and grid-type converters, and determine the first input vector increment based on the Jacobian matrix; Step d updates the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions based on the input vector increment; Step e determines whether the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions satisfies max(| x If |) is less than 0.0001, then the power angles of the grid-type and grid-type converters in the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions are taken as the steady-state power angles; otherwise, return to step b.

[0013] Furthermore, the initial value of the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters under normal operating conditions is [0,…,0,0,…0, V 0,…, V 0].

[0014] Furthermore, the Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step c is as follows:

[0015] In the above formula, The Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step c is... to These are the first to ninth sub-matrices.

[0016] Furthermore, the element in the k-th row and i-th column of the first submatrix The element in the k-th row and k-th column of the first submatrix The element in the k-th row and j-th column of the second submatrix The element in the k-th row and j-th column of the third submatrix The fourth submatrix l element in row i column The fifth submatrix l element in row j The fifth submatrix l Line 1 l Column elements The sixth submatrix l element in row j The sixth submatrix l Line 1 l Column elements The seventh submatrix l element in row i column The eighth submatrix l element in row j The eighth submatrix l Line 1 l Column elements The ninth submatrix l element in row j The ninth submatrix l Line 1 l Column elements .

[0017] Furthermore, the magnitude and phase angle of the self-coupling impedance coefficient of the k-th grid converter satisfy the following:

[0018] The magnitude and phase angle of the mutual coupling coefficient between the power grid and the grid-connected converter satisfy the following:

[0019] The amplitude and phase angle of the port mutual coupling coefficient of the grid-connected converter satisfy the following:

[0020] The first j The amplitude and phase angle of the port mutual coupling coefficient between the individual grid converter and the grid converter satisfy the following:

[0021] The magnitude and phase angle of the mutual coupling coefficient between the power grid and the grid-type converter satisfy the following:

[0022] The first j The amplitude and phase angle of the port intercoupling coefficient of the individual grid-type converter satisfy the following:

[0023] The amplitude and phase angle of the port mutual coupling coefficient between the grid-connected converter and the network-type converter satisfy the following:

[0024] The For the first l The equivalent conductance and equivalent susceptance of a grid-type converter satisfy:

[0025] In the above formula, For the first k The line impedance of the grid converter connected to the common coupling point. It is the reciprocal of the grid-connected equivalent impedance. For the first j The reciprocal of the line impedance from each grid-type converter to the point of common coupling. For the first l The reciprocal of the line impedance of a grid-type converter connected to a common coupling point.

[0026] Furthermore, the increment of the first input vector is as follows:

[0027] In the above formula, The increment of the first input vector; Furthermore, based on the input vector increment, the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions is updated to... .

[0028] Furthermore, the equilibrium point equation for the hybrid system of grid-type and grid-type converters during the fault period is as follows:

[0029]

[0030] In the above formula, let k∈[1,m], l ∈[1, n], where m is the total number of grid-connected converters and n is the total number of grid-connected converters. This is the input vector for the equilibrium point equations of the hybrid system of grid-type and grid-type converters during the fault period. This is the output vector of the equilibrium point equation for a hybrid system of grid-type and grid-type converters during a fault. Here is the voltage steady-state equation for the k-th grid-type converter; Furthermore, the aforementioned The power angles of the grid-connected converter and the grid-connected converter are replaced with the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions to obtain the following. , will the The power angles of the grid-connected converter and the grid-connected converter are replaced with the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions to obtain the following. .

[0031] Furthermore, the iterative solution of the equilibrium point equation of the hybrid system of grid-connected and grid-connected converters during the fault period, based on the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions, yields the current phase angle of each grid-connected converter and the output voltage of each grid-connected converter during the fault period, including: Step f initializes the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters during the fault period; Step g: Substitute the output vector of the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period into the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period to calculate the output vector of the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period. Step h constructs the Jacobian matrix of the current hybrid system of grid-type and grid-type converters, and determines the second input vector increment based on the Jacobian matrix; Step i incrementally updates the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period based on the input vector; Step k determines whether the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period satisfies max(| u If |) is less than 0.0001, then obtain the current phase angle of each grid converter and the output voltage of each grid converter in the input vector of the equilibrium point equation of the hybrid grid-type and grid-type converter system during the fault period; otherwise, return to step g.

[0032] Furthermore, during the fault period, the initial value of the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters is [0,…,0, V 0,…, V 0].

[0033] Furthermore, the Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step h is as follows:

[0034] In the above formula, The Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step h is... , These are the first and second sub-unit matrices.

[0035] Furthermore, the element in the k-th row and i-th column of the first sub-unit matrix The element in the k-th row and k-th column of the first sub-unit matrix The element in the k-th row and i-th column of the second sub-unit matrix .

[0036] Furthermore, the increment of the second input vector is as follows:

[0037] In the above formula, The increment of the input vector; Furthermore, based on the input vector increment, the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period is updated to... .

[0038] Furthermore, adjust the active / reactive current reference values ​​of the grid-connected converter and the active power reference values ​​of the grid-connected converter according to the following formula:

[0039]

[0040]

[0041] In the above formula, This is the active current reference value for the grid-type converter. Let k be the output voltage of the k-th grid converter. This is the reactive current reference value for the grid-type converter. Let the current phase angle be the k-th grid converter. This is the active power reference value for grid-type converters. For the first l Output voltage of a grid-type converter For the first l Steady-state power angle of a grid-type converter For the first j Output voltage of a grid-type converter For the first j Steady-state power angle of a grid-type converter Let be the steady-state power angle of the i-th grid-type converter. Let be the current phase angle of the i-th grid converter.

[0042] Secondly, a power current reshaping device for a hybrid system of grid-connected and grid-built converters under grid fault conditions is provided. The power current reshaping device for the hybrid system of grid-connected and grid-built converters under grid fault conditions includes: The first analysis module is used to iteratively solve the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions, and obtain the steady-state power angle of the grid-type and grid-type converters under normal operating conditions. The second analysis module is used to iteratively solve the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period based on the steady-state power angle of the grid-type and grid-type converters under normal operating conditions, so as to obtain the current phase angle of each grid-type converter and the output voltage of each grid-type converter during the fault period. The adjustment module is used to adjust the active / reactive current reference value of the grid-type converter and the active power reference value of the grid-type converter based on the steady-state power angle of the grid-type and grid-connected converters, the current phase angle of each grid-type converter and the output voltage of each grid-connected converter.

[0043] Thirdly, a computer device is provided, comprising: one or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the power current reshaping method for a hybrid system of grid-connected and grid-connected converters under grid fault conditions is implemented.

[0044] Fourthly, a computer-readable storage medium is provided, on which a computer program is stored, wherein when the computer program is executed, the power current reshaping method for a hybrid system of grid-connected and grid-connected converters under grid fault conditions is implemented.

[0045] The above-described technical solutions of the present invention have at least one or more of the following beneficial effects: This invention provides a power and current reshaping method and apparatus for a hybrid system of grid-connected and grid-connected converters under power grid fault conditions. The method includes: iteratively solving the equilibrium point equation of the hybrid system under normal operating conditions to obtain the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions; iteratively solving the equilibrium point equation of the hybrid system during a fault period based on the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions to obtain the current phase angle of each grid-connected converter and the output voltage of each grid-connected converter during the fault period; and adjusting the active / reactive current reference values ​​of the grid-connected converters and the active power reference values ​​of the grid-connected converters based on the steady-state power angles of the grid-connected and grid-connected converters, the current phase angles of each grid-connected converter, and the output voltages of each grid-connected converter. The technical solution provided by this invention targets a hybrid system composed of grid-connected and grid-connected converters. During grid faults, it simultaneously reshapes the current reference value of the grid-connected converter and the active power reference value of the grid-connected converter. By coordinating the transient response processes of the two types of converters, the transient stability of the hybrid system is improved. Attached Figure Description

[0046] Figure 1 This is a schematic flowchart of the main steps of the power current reshaping method for a hybrid system of grid-connected and grid-connected converters under grid fault conditions according to an embodiment of the present invention. Figure 2 This is a topology diagram of the hybrid system in the simulation of an embodiment of the present invention; Figure 3These are simulation results of a hybrid system that does not employ the power current reshaping method described in this invention, according to an embodiment of the present invention. Figure 4 This is a simulation result diagram of a hybrid system using the power current reshaping method described in this invention, according to an embodiment of the present invention. Detailed Implementation

[0047] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Example 1 See appendix Figure 1 , Figure 1 This is a schematic flowchart illustrating the main steps of a power current reshaping method for a hybrid grid-connected and grid-connected converter system under grid fault conditions, according to an embodiment of the present invention. Figure 1 As shown, the power current reshaping method for a hybrid system of grid-connected and grid-connected converters under grid fault conditions in this embodiment of the invention mainly includes the following steps: Step S101: Iteratively solve the equilibrium point equation of the hybrid system of grid-connected and grid-connected converters under normal operating conditions to obtain the steady-state power angle of the grid-connected and grid-connected converters under normal operating conditions; Step S102: Based on the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions, iteratively solve the equilibrium point equations of the hybrid system of grid-connected and grid-connected converters during the fault period to obtain the current phase angles of each grid-connected converter and the output voltages of each grid-connected converter during the fault period. Step S103: Based on the steady-state power angle of the grid-connected and grid-connected converters, the current phase angle of each grid-connected converter, and the output voltage of each grid-connected converter, adjust the active / reactive current reference value of the grid-connected converter and the active power reference value of the grid-connected converter.

[0050] In this embodiment, the equilibrium point equation of the hybrid system of grid-connected and grid-connected converters under normal operating conditions is as follows:

[0051]

[0052] In the above formula, let k∈[1,m], l∈[1, n], where m is the total number of grid-connected converters and n is the total number of grid-connected converters. This is the input vector for the equilibrium point equations of a hybrid system of grid-type and grid-type converters under normal operating conditions. For the power angle of the k-th grid converter, For the first l The power angle of a grid-type converter For the first l Output voltage of a grid-type converter It is the transpose symbol. This is the output vector of the equilibrium point equations for a hybrid system of grid-type and grid-type converters under normal operating conditions. The voltage equation for the k-th grid converter is... For the first l The active power equation for a grid-type converter. For the first l The reactive power equations for a grid-type converter.

[0053] In one embodiment, the voltage equation of the k-th grid converter is as follows:

[0054] The first l The active power equation for a grid-type converter is as follows:

[0055] The first l The reactive power equation for a grid-type converter is as follows:

[0056] In the above formula, Let x be the magnitude of the self-coupling impedance coefficient of the k-th grid converter. Let be the output current of the k-th grid converter. The phase angle is the self-coupling impedance coefficient of the k-th grid converter. Let the current phase angle be the k-th grid converter. This represents the amplitude of the mutual coupling coefficient between the power grid and the grid-connected converter. This is the three-phase grid voltage. The phase angle is the mutual coupling coefficient between the power grid and the grid-connected converter. To match the amplitude of the port mutual coupling coefficient of the grid converter, Let i be the output current of the i-th grid converter. To match the phase angle of the port mutual coupling coefficient of the grid converter, Let be the power angle difference between the i-th grid converter and the k-th grid converter. Let i be the current phase angle of the i-th grid converter. For the first j The amplitude of the port mutual coupling coefficient between the individual grid-type converter and the grid-type converter. For the first j Output voltage of a grid-type converter For the first j The phase angle of the mutual coupling coefficient between the ports of the individual grid-type converter and the grid-type converter. For the first j The power angle of a grid-type converter This is a reference value for active power. This represents the amplitude of the mutual coupling coefficient between the power grid and the grid-connected converter. The phase angle is the mutual coupling coefficient between the power grid and the grid-connected converter. For the first l Equivalent conductance of a grid-type converter For the first j The amplitude of the port mutual coupling coefficient of a grid-type converter. For the first j Output voltage of a grid-type converter for For the first l The grid-type converter and the first j The power angle difference of a grid-type converter For the first j The phase angle of the port mutual coupling coefficient of the grid-type converter. The amplitude of the mutual coupling coefficient between the grid converter and the grid converter port. The phase angle of the mutual coupling coefficient between the grid converter and the port of the grid converter is... For the first l The reactive power droop factor of a grid-type converter This is a reference value for reactive power. For the first l The equivalent susceptance of a grid-type converter V 0 represents the rated voltage. Let be the power angle of the i-th grid converter.

[0057] In one implementation, the iterative solution of the equilibrium point equations for the hybrid system of grid-connected and grid-connected converters under normal operating conditions to obtain the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions includes: Step a: Initialize the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters under normal operating conditions; Step b: Substitute the output vector of the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions into the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions, and calculate the output vector of the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions. Step c: Construct the Jacobian matrix of the current hybrid system of grid-type and grid-type converters, and determine the first input vector increment based on the Jacobian matrix; Step d updates the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions based on the input vector increment; Step e determines whether the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions satisfies max(| x If |) is less than 0.0001, then the power angles of the grid-type and grid-type converters in the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions are taken as the steady-state power angles; otherwise, return to step b.

[0058] In one implementation, the initial value of the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters under normal operating conditions is [0,…,0,0,…0, V 0,…, V 0].

[0059] In one implementation, the Jacobian matrix of the current hybrid grid-type and grid-type converter system constructed in step c is as follows:

[0060] In the above formula, The Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step c is... to These are the first to ninth sub-matrices.

[0061] In one implementation, the element in the k-th row and i-th column of the first submatrix The element in the k-th row and k-th column of the first submatrix The element in the k-th row and j-th column of the second submatrix The element in the k-th row and j-th column of the third submatrix The fourth submatrix l element in row i column The fifth submatrix l element in row j The fifth submatrix l Line 1 l Column elements The sixth submatrix l element in row j The sixth submatrix l Line 1 l Column elements The seventh submatrix l element in row i column The eighth submatrix l element in row j The eighth submatrix l Line 1 l Column elements The ninth submatrix l element in row j The ninth submatrix l Line 1 l Column elements .

[0062] In one implementation, the magnitude of the self-coupling impedance coefficient and the phase angle of the k-th grid converter satisfy the following:

[0063] The magnitude and phase angle of the mutual coupling coefficient between the power grid and the grid-connected converter satisfy the following:

[0064] The amplitude and phase angle of the port mutual coupling coefficient of the grid-connected converter satisfy the following:

[0065] The first j The amplitude and phase angle of the port mutual coupling coefficient between the individual grid converter and the grid converter satisfy the following:

[0066] The magnitude and phase angle of the mutual coupling coefficient between the power grid and the grid-type converter satisfy the following:

[0067] The first j The amplitude and phase angle of the port intercoupling coefficient of the individual grid-type converter satisfy the following:

[0068] The amplitude and phase angle of the port mutual coupling coefficient between the grid-connected converter and the network-type converter satisfy the following:

[0069] The For the first l The equivalent conductance and equivalent susceptance of a grid-type converter satisfy:

[0070] In the above formula, For the first k The line impedance of the grid converter connected to the common coupling point. It is the reciprocal of the grid-connected equivalent impedance. For the first jThe reciprocal of the line impedance from each grid-type converter to the point of common coupling. For the first l The reciprocal of the line impedance of a grid-type converter connected to a common coupling point.

[0071] In one implementation, the increment of the first input vector is as follows:

[0072] In the above formula, The increment of the first input vector; In one implementation, the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions is updated based on the input vector increment. .

[0073] In one implementation, the equilibrium point equation for the hybrid grid-type and grid-type converter system during the fault period is as follows:

[0074]

[0075] In the above formula, let k∈[1,m], l ∈[1, n], where m is the total number of grid-connected converters and n is the total number of grid-connected converters. This is the input vector for the equilibrium point equations of the hybrid system of grid-type and grid-type converters during the fault period. This is the output vector of the equilibrium point equation for a hybrid system of grid-type and grid-type converters during a fault. Here is the voltage steady-state equation for the k-th grid-type converter; In one implementation, the The power angles of the grid-connected converter and the grid-connected converter are replaced with the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions to obtain the following. , will the The power angles of the grid-connected converter and the grid-connected converter are replaced with the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions to obtain the following. .

[0076] In one implementation, the iterative solution of the equilibrium point equation of the hybrid system of grid-connected and grid-connected converters during the fault period based on the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions, to obtain the current phase angle of each grid-connected converter and the output voltage of each grid-connected converter during the fault period, includes: Step f initializes the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters during the fault period; Step g: Substitute the output vector of the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period into the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period to calculate the output vector of the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period. Step h constructs the Jacobian matrix of the current hybrid system of grid-type and grid-type converters, and determines the second input vector increment based on the Jacobian matrix; Step i incrementally updates the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period based on the input vector; Step k determines whether the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period satisfies max(| u If |) is less than 0.0001, then obtain the current phase angle of each grid converter and the output voltage of each grid converter in the input vector of the equilibrium point equation of the hybrid grid-type and grid-type converter system during the fault period; otherwise, return to step g.

[0077] In one implementation, the initial value of the input vector of the equilibrium point equation for the hybrid grid-type and grid-type converter system during the fault period is [0,…,0,…]. V 0,…, V 0].

[0078] In one implementation, the Jacobian matrix of the current hybrid grid-type and grid-type converter system constructed in step h is as follows:

[0079] In the above formula, The Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step h is... , These are the first and second sub-unit matrices.

[0080] In one implementation, the element in the k-th row and i-th column of the first sub-unit matrix... The element in the k-th row and k-th column of the first sub-unit matrix The element in the k-th row and i-th column of the second sub-unit matrix .

[0081] In one implementation, the second input vector increment is as follows:

[0082] In the above formula, The increment of the input vector; In one implementation, the input vector of the equilibrium point equation for the hybrid grid-type and grid-type converter system during a fault is updated based on the input vector increment. .

[0083] In one implementation, the active / reactive current reference values ​​of the grid-connected converter and the active power reference values ​​of the grid-connected converter are adjusted according to the following formula:

[0084]

[0085]

[0086] In the above formula, This is the active current reference value for the grid-type converter. Let k be the output voltage of the k-th grid converter. This is the reactive current reference value for the grid-type converter. Let the current phase angle be the k-th grid converter. This is the active power reference value for grid-type converters. For the first l Output voltage of a grid-type converter For the first l Steady-state power angle of a grid-type converter For the first j Output voltage of a grid-type converter For the first j Steady-state power angle of a grid-type converter Let be the steady-state power angle of the i-th grid-type converter. Let be the current phase angle of the i-th grid converter.

[0087] In one specific implementation, MATLAB / Simulink simulation was performed to demonstrate the technical achievements of this solution. Figure 2 This is the topology diagram of the hybrid system in the simulation. Figure 1 As can be seen, this topology includes a DC-side power supply, a three-phase full-bridge inverter circuit, filter inductors, filter capacitors, a grid-connected converter, a grid-connected converter, and grid-connected equivalent impedance. Z g and three-phase grid voltage V g .

[0088] The specific parameters are set as follows: the base frequency of the grid-connected voltage is 50Hz, the sampling frequency of the grid-connected converter and the grid-connected converter is 16kHz, and the rated value of the grid-connected voltage Vg is 311V.

[0089] By establishing a system simulation model and setting the three-phase voltage to a symmetrical drop to 0.2 pu, a comparative simulation was conducted on the operating conditions without and with the fault ride-through strategy of this invention. The simulation results are as follows: Figure 3 and Figure 4 As shown. Figure 3 In a hybrid system that does not employ the power current reshaping method described in this invention, the power angle of one of the grid-connected converters in the system after the three-phase grid voltage drops to 0.2 pu The power angle of a grid-type converter Simulation results; Figure 4 The power angle simulation results of one grid-connected converter and one grid-connected converter in a hybrid system using the power current reshaping method described in this invention, after the three-phase grid voltage drops to 0.2 pu.

[0090] Example 2 Based on the same inventive concept, this invention also provides a power current reshaping device for a hybrid system of grid-connected and grid-built converters under grid fault conditions. The power current reshaping device for this hybrid system includes: The first analysis module is used to iteratively solve the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions, and obtain the steady-state power angle of the grid-type and grid-type converters under normal operating conditions. The second analysis module is used to iteratively solve the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period based on the steady-state power angle of the grid-type and grid-type converters under normal operating conditions, so as to obtain the current phase angle of each grid-type converter and the output voltage of each grid-type converter during the fault period. The adjustment module is used to adjust the active / reactive current reference value of the grid-type converter and the active power reference value of the grid-type converter based on the steady-state power angle of the grid-type and grid-connected converters, the current phase angle of each grid-type converter and the output voltage of each grid-connected converter.

[0091] Preferably, the equilibrium point equation for the hybrid system of grid-connected and grid-connected converters under normal operating conditions is as follows:

[0092]

[0093] In the above formula, let k∈[1,m], l ∈[1, n], where m is the total number of grid-connected converters and n is the total number of grid-connected converters. This is the input vector for the equilibrium point equations of a hybrid system of grid-type and grid-type converters under normal operating conditions. For the power angle of the k-th grid converter, For the first l The power angle of a grid-type converter For the first l Output voltage of a grid-type converter It is the transpose symbol. This is the output vector of the equilibrium point equations for a hybrid system of grid-type and grid-type converters under normal operating conditions. The voltage equation for the k-th grid converter is... For the first l The active power equation for a grid-type converter. For the first l The reactive power equations for a grid-type converter.

[0094] Furthermore, the voltage equation for the k-th grid converter is as follows:

[0095] The first l The active power equation for a grid-type converter is as follows:

[0096] The first l The reactive power equation for a grid-type converter is as follows:

[0097] In the above formula, Let x be the magnitude of the self-coupling impedance coefficient of the k-th grid converter. Let be the output current of the k-th grid converter. The phase angle is the self-coupling impedance coefficient of the k-th grid converter. Let the current phase angle be the k-th grid converter. This represents the amplitude of the mutual coupling coefficient between the power grid and the grid-connected converter. This is the three-phase grid voltage. The phase angle is the mutual coupling coefficient between the power grid and the grid-connected converter. To match the amplitude of the port mutual coupling coefficient of the grid converter, Let i be the output current of the i-th grid converter. To match the phase angle of the port mutual coupling coefficient of the grid converter, Let be the power angle difference between the i-th grid converter and the k-th grid converter. Let i be the current phase angle of the i-th grid converter. For the first j The amplitude of the port mutual coupling coefficient between the individual grid-type converter and the grid-type converter. For the first j Output voltage of a grid-type converter For the first j The phase angle of the mutual coupling coefficient between the ports of the individual grid-type converter and the grid-type converter. For the first j The power angle of a grid-type converter This is a reference value for active power. This represents the amplitude of the mutual coupling coefficient between the power grid and the grid-connected converter. The phase angle is the mutual coupling coefficient between the power grid and the grid-connected converter. For the first l Equivalent conductance of a grid-type converter For the first j The amplitude of the port mutual coupling coefficient of a grid-type converter. For the first j Output voltage of a grid-type converter For the first l The grid-type converter and the first j The power angle difference of a grid-type converter For the first j The phase angle of the port mutual coupling coefficient of the grid-type converter. The amplitude of the mutual coupling coefficient between the grid converter and the grid converter port. The phase angle of the mutual coupling coefficient between the grid converter and the port of the grid converter is... For the first l The reactive power droop factor of a grid-type converter This is a reference value for reactive power. For the first l The equivalent susceptance of a grid-type converter V 0 represents the rated voltage. Let be the power angle of the i-th grid converter.

[0098] Furthermore, the iterative solution of the equilibrium point equations for the hybrid system of grid-connected and grid-connected converters under normal operating conditions to obtain the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions includes: Step a: Initialize the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters under normal operating conditions; Step b: Substitute the output vector of the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions into the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions, and calculate the output vector of the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions. Step c: Construct the Jacobian matrix of the current hybrid system of grid-type and grid-type converters, and determine the first input vector increment based on the Jacobian matrix; Step d updates the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions based on the input vector increment; Step e determines whether the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions satisfies max(| xIf |) is less than 0.0001, then the power angles of the grid-type and grid-type converters in the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions are taken as the steady-state power angles; otherwise, return to step b.

[0099] Furthermore, the initial value of the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters under normal operating conditions is [0,…,0,0,…0, V 0,…, V 0].

[0100] Furthermore, the Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step c is as follows:

[0101] In the above formula, The Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step c is... to These are the first to ninth sub-matrices.

[0102] Furthermore, the element in the k-th row and i-th column of the first submatrix The element in the k-th row and k-th column of the first submatrix The element in the k-th row and j-th column of the second submatrix The element in the k-th row and j-th column of the third submatrix The fourth submatrix l element in row i column The fifth submatrix l element in row j The fifth submatrix l Line 1 l Column elements The sixth submatrix l element in row j The sixth submatrix l Line 1 l Column elements The seventh submatrix l element in row i column The eighth submatrix l element in row j The eighth submatrix l Line 1 l Column elements The ninth submatrix l element in row j The ninth submatrix l Line 1 l Column elements .

[0103] Furthermore, the magnitude and phase angle of the self-coupling impedance coefficient of the k-th grid converter satisfy the following:

[0104] The magnitude and phase angle of the mutual coupling coefficient between the power grid and the grid-connected converter satisfy the following:

[0105] The amplitude and phase angle of the port mutual coupling coefficient of the grid-connected converter satisfy the following:

[0106] The first j The amplitude and phase angle of the port mutual coupling coefficient between the individual grid converter and the grid converter satisfy the following:

[0107] The magnitude and phase angle of the mutual coupling coefficient between the power grid and the grid-type converter satisfy the following:

[0108] The first j The amplitude and phase angle of the port intercoupling coefficient of the individual grid-type converter satisfy the following:

[0109] The amplitude and phase angle of the port mutual coupling coefficient between the grid-connected converter and the network-type converter satisfy the following:

[0110] The For the first l The equivalent conductance and equivalent susceptance of a grid-type converter satisfy:

[0111] In the above formula, For the first k The line impedance of the grid converter connected to the common coupling point. It is the reciprocal of the grid-connected equivalent impedance. For the first j The reciprocal of the line impedance from each grid-type converter to the point of common coupling. For the first l The reciprocal of the line impedance of a grid-type converter connected to a common coupling point.

[0112] Furthermore, the increment of the first input vector is as follows:

[0113] In the above formula, The increment of the first input vector; Furthermore, based on the input vector increment, the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions is updated to... .

[0114] Furthermore, the equilibrium point equation for the hybrid system of grid-type and grid-type converters during the fault period is as follows:

[0115]

[0116] In the above formula, let k∈[1,m], l ∈[1, n], where m is the total number of grid-connected converters and n is the total number of grid-connected converters. This is the input vector for the equilibrium point equations of the hybrid system of grid-type and grid-type converters during the fault period. This is the output vector of the equilibrium point equation for a hybrid system of grid-type and grid-type converters during a fault. Here is the voltage steady-state equation for the k-th grid-type converter; Furthermore, the aforementioned The power angles of the grid-connected converter and the grid-connected converter are replaced with the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions to obtain the following. , will the The power angles of the grid-connected converter and the grid-connected converter are replaced with the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions to obtain the following. .

[0117] Furthermore, the iterative solution of the equilibrium point equation of the hybrid system of grid-connected and grid-connected converters during the fault period, based on the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions, yields the current phase angle of each grid-connected converter and the output voltage of each grid-connected converter during the fault period, including: Step f initializes the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters during the fault period; Step g: Substitute the output vector of the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period into the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period to calculate the output vector of the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period. Step h constructs the Jacobian matrix of the current hybrid system of grid-type and grid-type converters, and determines the second input vector increment based on the Jacobian matrix; Step i incrementally updates the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period based on the input vector; Step k determines whether the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period satisfies max(| u If |) is less than 0.0001, then obtain the current phase angle of each grid converter and the output voltage of each grid converter in the input vector of the equilibrium point equation of the hybrid grid-type and grid-type converter system during the fault period; otherwise, return to step g.

[0118] Furthermore, during the fault period, the initial value of the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters is [0,…,0, V 0,…, V 0].

[0119] Furthermore, the Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step h is as follows:

[0120] In the above formula, The Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step h is... , These are the first and second sub-unit matrices.

[0121] Furthermore, the element in the k-th row and i-th column of the first sub-unit matrix The element in the k-th row and k-th column of the first sub-unit matrix The element in the k-th row and i-th column of the second sub-unit matrix .

[0122] Furthermore, the increment of the second input vector is as follows:

[0123] In the above formula, The increment of the input vector; Furthermore, based on the input vector increment, the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period is updated to... .

[0124] Furthermore, adjust the active / reactive current reference values ​​of the grid-connected converter and the active power reference values ​​of the grid-connected converter according to the following formula:

[0125]

[0126]

[0127] In the above formula, This is the active current reference value for the grid-type converter. Let k be the output voltage of the k-th grid converter. This is the reactive current reference value for the grid-type converter. Let the current phase angle be the k-th grid converter. This is the active power reference value for grid-type converters. For the first l Output voltage of a grid-type converter For the first l Steady-state power angle of a grid-type converter For the first j Output voltage of a grid-type converter For the first j Steady-state power angle of a grid-type converter Let be the steady-state power angle of the i-th grid-type converter. Let be the current phase angle of the i-th grid converter.

[0128] Example 3 Based on the same inventive concept, this invention also provides a computer device, which includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to achieve corresponding method flows or corresponding functions, thereby implementing the steps of the power current reshaping method for a hybrid grid-connected and grid-connected converter system under grid fault conditions in the above embodiments.

[0129] Example 4 Based on the same inventive concept, this invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the power current reshaping method for a hybrid grid-connected and grid-connected converter system under grid fault conditions in the above embodiments.

[0130] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0131] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0132] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0133] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A power current reshaping method for a hybrid system of grid-connected and grid-connected converters under grid fault conditions, characterized in that, The method includes: The equilibrium point equations of the hybrid system of grid-connected and grid-connected converters under normal operating conditions are solved iteratively to obtain the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions. Based on the steady-state power angles of the grid-type and grid-type converters under normal operating conditions, the equilibrium point equations of the hybrid system of grid-type and grid-type converters during the fault period are iteratively solved to obtain the current phase angles of each grid-type converter and the output voltages of each grid-type converter during the fault period. Based on the steady-state power angle of the grid-type and grid-type converters, the current phase angle of each grid-type converter, and the output voltage of each grid-type converter, the active / reactive current reference values ​​of the grid-type converter and the active power reference values ​​of the grid-type converter are adjusted.

2. The method as described in claim 1, characterized in that, The equilibrium point equation for the hybrid system of grid-connected and grid-type converters under normal operating conditions is as follows: In the above formula, let k∈[1,m], l ∈[1, n], where m is the total number of grid-connected converters and n is the total number of grid-connected converters. This is the input vector for the equilibrium point equations of a hybrid system of grid-type and grid-type converters under normal operating conditions. For the power angle of the k-th grid converter, For the first l The power angle of a grid-type converter For the first l Output voltage of a grid-type converter It is the transpose symbol. This is the output vector of the equilibrium point equations for a hybrid system of grid-type and grid-type converters under normal operating conditions. The voltage equation for the k-th grid converter is... For the first l The active power equation for a grid-type converter. For the first l The reactive power equations for a grid-type converter.

3. The method as described in claim 2, characterized in that, The voltage equation for the k-th grid converter is as follows: The first l The active power equation for a grid-type converter is as follows: The first l The reactive power equation for a grid-type converter is as follows: In the above formula, Let x be the magnitude of the self-coupling impedance coefficient of the k-th grid converter. Let be the output current of the k-th grid converter. The phase angle is the self-coupling impedance coefficient of the k-th grid converter. Let the current phase angle be the k-th grid converter. This represents the amplitude of the mutual coupling coefficient between the power grid and the grid-connected converter. This is the three-phase grid voltage. The phase angle is the mutual coupling coefficient between the power grid and the grid-connected converter. To the amplitude of the port mutual coupling coefficient of the grid converter, Let i be the output current of the i-th grid converter. To match the phase angle of the port mutual coupling coefficient of the grid converter, Let be the power angle difference between the i-th grid converter and the k-th grid converter. Let i be the current phase angle of the i-th grid converter. For the first j The amplitude of the port mutual coupling coefficient between the individual grid-type converter and the grid-type converter. For the first j Output voltage of a grid-type converter For the first j The phase angle of the mutual coupling coefficient between the ports of the individual grid-type converter and the grid-type converter. For the first j The power angle of a grid-type converter This is a reference value for active power. This represents the amplitude of the mutual coupling coefficient between the power grid and the grid-connected converter. The phase angle is the mutual coupling coefficient between the power grid and the grid-connected converter. For the first l The equivalent conductance of a grid-type converter For the first j The amplitude of the port mutual coupling coefficient of a grid-type converter. For the first j Output voltage of a grid-type converter For the first l The grid-type converter and the first j The power angle difference of a grid-type converter For the first j The phase angle of the port mutual coupling coefficient of the grid-type converter. The amplitude of the mutual coupling coefficient between the grid converter and the grid converter port. The phase angle of the mutual coupling coefficient between the grid converter and the port of the grid converter is... For the first l The reactive power droop factor of a grid-type converter This is a reference value for reactive power. For the first l The equivalent susceptance of a grid-type converter V 0 represents the rated voltage. Let be the power angle of the i-th grid converter.

4. The method as described in claim 3, characterized in that, The iterative solution of the equilibrium point equations for the hybrid system of grid-connected and grid-connected converters under normal operating conditions yields the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions, including: Step a: Initialize the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters under normal operating conditions; Step b: Substitute the output vector of the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions into the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions, and calculate the output vector of the equilibrium point equation of the hybrid system of grid-connected and grid-structured converters under normal operating conditions. Step c: Construct the Jacobian matrix of the current hybrid system of grid-type and grid-type converters, and determine the first input vector increment based on the Jacobian matrix; Step d updates the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions based on the input vector increment; Step e determines whether the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions satisfies max(| x If |) is less than 0.0001, then the power angles of the grid-type and grid-type converters in the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions are taken as the steady-state power angles; otherwise, return to step b.

5. The method as described in claim 4, characterized in that, The initial value of the input vector for the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions is [0,…,0,0,…0, V 0,…, V 0].

6. The method as described in claim 4, characterized in that, The Jacobian matrix of the hybrid system of grid-type and grid-type converters constructed in step c is as follows: In the above formula, The Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step c is... to These are the first to ninth sub-matrices.

7. The method as described in claim 6, characterized in that, The element in the k-th row and i-th column of the first submatrix The element in the k-th row and k-th column of the first submatrix The element in the k-th row and j-th column of the second submatrix The element in the k-th row and j-th column of the third submatrix The fourth submatrix l element in row i column The fifth submatrix l element in row j The fifth submatrix l Line number l Column elements The sixth submatrix l element in row j The sixth submatrix l Line number l Column elements The seventh submatrix l element in row i column The eighth submatrix l element in row j The eighth submatrix l Line number l Column elements The ninth submatrix l element in row j The ninth submatrix l Line number l Column elements .

8. The method as described in claim 6, characterized in that, The magnitude and phase angle of the self-coupling impedance coefficient of the k-th grid converter satisfy the following: The magnitude and phase angle of the mutual coupling coefficient between the power grid and the grid-connected converter satisfy the following: The amplitude and phase angle of the port mutual coupling coefficient of the grid-connected converter satisfy the following: The first j The amplitude and phase angle of the port mutual coupling coefficient between the individual grid converter and the grid converter satisfy the following: The magnitude and phase angle of the mutual coupling coefficient between the power grid and the grid-type converter satisfy the following: The first j The amplitude and phase angle of the port intercoupling coefficient of the individual grid-type converter satisfy the following: The amplitude and phase angle of the port mutual coupling coefficient between the grid-connected converter and the network-type converter satisfy the following: The For the first l The equivalent conductance and equivalent susceptance of a grid-type converter satisfy: In the above formula, For the first k The line impedance of the grid converter connected to the common coupling point. It is the reciprocal of the grid-connected equivalent impedance. For the first j The reciprocal of the line impedance from each grid-type converter to the point of common coupling. For the first l The reciprocal of the line impedance of a grid-type converter connected to a common coupling point.

9. The method as described in claim 6, characterized in that, The increment of the first input vector is as follows: In the above formula, This is the increment of the first input vector.

10. The method as described in claim 9, characterized in that, Based on the input vector increment, the input vector of the equilibrium point equation of the hybrid system of grid-type and network-type converters under normal operating conditions is updated as follows: .

11. The method as described in claim 10, characterized in that, The equilibrium point equation for the hybrid system of grid-type and grid-type converters during the fault period is as follows: In the above formula, let k∈[1,m], l ∈[1, n], where m is the total number of grid-connected converters and n is the total number of grid-connected converters. This is the input vector for the equilibrium point equations of the hybrid system of grid-type and grid-type converters during the fault period. This is the output vector of the equilibrium point equation for a hybrid system of grid-type and grid-type converters during a fault. This is the voltage steady-state equation for the k-th grid-type converter.

12. The method as described in claim 11, characterized in that, The The power angles of the grid-connected converter and the grid-connected converter are replaced with the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions to obtain the following. , will the The power angles of the grid-connected converter and the grid-connected converter are replaced with the steady-state power angles of the grid-connected and grid-connected converters under normal operating conditions to obtain the following. .

13. The method as described in claim 11, characterized in that, The equilibrium point equation of the hybrid system of grid-connected and grid-type converters during the fault period is iteratively solved based on the steady-state power angles of the grid-connected and grid-type converters under normal operating conditions. This yields the current phase angle of each grid-connected converter and the output voltage of each grid-type converter during the fault period, including: Step f initializes the input vector of the equilibrium point equation for the hybrid system of grid-type and grid-type converters during the fault period; Step g: Substitute the output vector of the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period into the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period to calculate the output vector of the equilibrium point equation of the hybrid system of grid-type and grid-structured converters during the fault period. Step h constructs the Jacobian matrix of the current hybrid system of grid-type and grid-type converters, and determines the second input vector increment based on the Jacobian matrix; Step i incrementally updates the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period based on the input vector; Step k determines whether the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period satisfies max(| u If |) is less than 0.0001, then obtain the current phase angle of each grid converter and the output voltage of each grid converter in the input vector of the equilibrium point equation of the hybrid grid-type and grid-type converter system during the fault period; otherwise, return to step g.

14. The method as described in claim 13, characterized in that, During the fault period, the initial value of the input vector of the equilibrium point equation of the hybrid system of grid-type and grid-type converters is [0,…,0, V 0,…, V 0].

15. The method as described in claim 13, characterized in that, The Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step h is as follows: In the above formula, The Jacobian matrix of the current hybrid system of grid-type and grid-type converters constructed in step h is... , These are the first and second sub-unit matrices.

16. The method as described in claim 15, characterized in that, The element in the k-th row and i-th column of the first sub-unit matrix The element in the k-th row and k-th column of the first sub-unit matrix The element in the k-th row and i-th column of the second sub-unit matrix .

17. The method as described in claim 16, characterized in that, The increment of the second input vector is as follows: In the above formula, This is the increment of the input vector.

18. The method as described in claim 17, characterized in that, Based on the input vector increment, the input vector of the equilibrium point equation of the hybrid system of grid-type and network-type converters during the fault period is updated as follows: .

19. The method as described in claim 18, characterized in that, Adjust the active / reactive current reference values ​​of the grid-connected converter and the active power reference values ​​of the grid-connected converter according to the following formula: In the above formula, This is the active current reference value for the grid-type converter. Let k be the output voltage of the k-th grid converter. This is the reactive current reference value for the grid-type converter. Let the current phase angle be the k-th grid converter. This is the active power reference value for grid-type converters. For the first l Output voltage of a grid-type converter For the first l Steady-state power angle of a grid-type converter For the first j Output voltage of a grid-type converter For the first j Steady-state power angle of a grid-type converter Let be the steady-state power angle of the i-th grid-type converter. Let be the current phase angle of the i-th grid converter.

20. An apparatus for power current reshaping of a hybrid system of grid-connected and grid-connected converters under grid fault conditions as described in any one of claims 1-19, characterized in that, The device includes: The first analysis module is used to iteratively solve the equilibrium point equation of the hybrid system of grid-type and grid-type converters under normal operating conditions, and obtain the steady-state power angle of the grid-type and grid-type converters under normal operating conditions. The second analysis module is used to iteratively solve the equilibrium point equation of the hybrid system of grid-type and grid-type converters during the fault period based on the steady-state power angle of the grid-type and grid-type converters under normal operating conditions, so as to obtain the current phase angle of each grid-type converter and the output voltage of each grid-type converter during the fault period. The adjustment module is used to adjust the active / reactive current reference value of the grid-type converter and the active power reference value of the grid-type converter based on the steady-state power angle of the grid-type and grid-connected converters, the current phase angle of each grid-type converter and the output voltage of each grid-connected converter.

21. A computer device, characterized in that, include: One or more processors; The processor is used to execute one or more programs; When the one or more programs are executed by the one or more processors, the power current reshaping method for a hybrid system of grid-connected and grid-connected converters under grid fault conditions as described in any one of claims 1 to 19 is implemented.

22. A computer-readable storage medium, characterized in that, It contains a computer program, which, when executed, implements the power current reshaping method for a hybrid system of grid-connected and grid-connected converters under grid fault conditions as described in any one of claims 1 to 19.

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