Power electronic equipment low voltage ride through control method and system

Abstract

The invention provides a low-voltage ride-through control method and system for power electronic equipment. The method comprises the steps that the control mode of the power electronic equipment is set to be double-closed-loop control; in the double-closed-loop control mode, according to outer-loop control parameters of the power electronic equipment, instruction values of positive and negative sequence currents of outer-loop control are calculated; carrying out amplitude limiting on the instruction values of the positive and negative sequence current, and carrying out vector fusion on the instruction values of the positive and negative sequence current after amplitude limiting to obtain the instruction values of the positive and negative sequence current after the maximum value is limited; performing positive and negative sequence current control according to the positive and negative sequence current instruction value after the maximum value is limited, and completing low-voltage ride-through; vector fusion is carried out on the instruction values of the positive sequence current and the negative sequence current after amplitude limiting, fault current suppression based on the low voltage ride through process can be achieved, the large overcurrent phenomenon is avoided, tripping conditions are reduced, and it is guaranteed that low voltage ride through can be achieved with high probability on the premise that normal control strategy logic is not affected.

Description

Technical Field

[0001] The patent application of this invention belongs to the technical field of low voltage ride-through, and specifically relates to a low voltage ride-through control method and system for power electronic equipment. Background Art

[0002] With the continuous increase in the installed capacity of new energy sources, the power flow direction in the power grid has gradually changed from the original one-way flow to multi-directional flow, and the continuous development of power electronics technology has also provided more ways and methods for actively controlling the two-way power flow. Existing power electronic equipment often requires the ability to perform low voltage ride-through during operation, that is, it needs to be able to restore the original stable working state when experiencing a short-duration fault, which requires a clear low voltage ride-through control strategy.

[0003] In actual use, the existing low voltage ride-through control strategy often causes tripping due to some additional conditions generated after the voltage drops. A common phenomenon is that a large overcurrent phenomenon is generated during the excessive voltage drop. In particular, the superposition of positive and negative sequence currents during the fault period will cause tripping, resulting in fault ride-through often requiring a long period of testing to explore appropriate control parameters. Summary of the invention

[0004] In order to overcome the above-mentioned deficiencies of the prior art, the present invention patent application proposes a low voltage ride-through control method for power electronic equipment, comprising:

[0005] Setting the control mode of the power electronic equipment to dual closed-loop control; in the dual closed-loop control mode, calculating the command values ​​of the positive and negative sequence currents of the outer loop control according to the outer loop control parameters of the power electronic equipment;

[0006] Limiting the command values ​​of the positive and negative sequence currents, and performing vector fusion on the command values ​​of the positive and negative sequence currents after the limiting, to obtain the positive and negative sequence current command values ​​after limiting the maximum values;

[0007] According to the positive and negative sequence current command values ​​after limiting the maximum value, positive and negative sequence current control is performed to complete low voltage ride through.

[0008] Preferably, the dual closed-loop control includes an outer-loop control and an inner-loop control, the outer-loop control adopts a network-building type control or a network-following type control, and the inner-loop control adopts a constant current control.

[0009] Preferably, the command values ​​of the positive and negative sequence currents include a command value of the positive sequence current and a command value of the negative sequence current; in the dual closed-loop control mode, according to the outer loop control parameters of the power electronic equipment, calculating the command values ​​of the positive and negative sequence currents of the outer loop control includes:

[0010] In the dual closed-loop control mode, according to the outer loop control parameters of the power electronic equipment, the command value calculation formula of the positive sequence current is used to calculate the command value of the positive sequence current under the outer loop control;

[0011] According to the outer loop control parameters of the power electronic equipment, the command value of the negative sequence current is calculated using the command value calculation formula of the negative sequence current under the outer loop control;

[0012] Among them, the outer loop control parameters include one or more of the following: the AC voltage d-axis measured value, the AC voltage q-axis measured value, the active power command value, the reactive power command value, the first proportional coefficient, the first integral coefficient, the Laplace operator, the second proportional coefficient and the second integral coefficient; the command value of the positive-sequence current is the positive-sequence d-axis current command value and the positive-sequence q-axis current command value; the command value of the negative-sequence current is the negative-sequence d-axis current command value and the negative-sequence q-axis current command value.

[0013] Preferably, the command value calculation formula of the positive sequence current includes a first calculation formula and a second calculation formula; the command value calculation formula of the positive sequence current is used to calculate the command value of the positive sequence current under the outer loop control according to the outer loop control parameters of the power electronic equipment, including:

[0014] When the outer loop control is grid-following control, the first calculation formula is used to calculate the command value of the positive sequence current according to the double closed-loop control parameters;

[0015] When the outer loop control is a network-forming control, the second calculation formula is used to calculate the command value of the positive sequence current according to the double closed-loop control parameters;

[0016] The second calculation formula is a Laplace transform formula of the transfer function of the grid-type controller of the positive sequence current.

[0017] Preferably, the first calculation formula is as follows:

[0018]

[0019] Among them, i+ d is the positive sequence d-axis current command value, i+ q is the positive sequence q-axis current command value, u d is the measured value of the AC voltage q axis, p is the active power command value, u q The d-axis measured value of the AC voltage, and q is the reactive power command value.

[0020] Preferably, the second calculation formula is as follows:

[0021] G(S)=KP1+Ki1÷S

[0022] Among them, G(S) is the Laplace transform of the transfer function of the grid-type controller of the positive sequence current, KP1 is the first proportional coefficient, Ki1 is the first integral coefficient, and S is the Laplace operator.

[0023] Preferably, the negative sequence current command value calculation formula includes: a third calculation formula; the negative sequence current command value calculation formula is used according to the outer loop control parameter of the power electronic equipment to calculate the negative sequence current command value under the outer loop control, including:

[0024] When the outer loop control is grid-following control, the command value of the negative sequence current is set to 0;

[0025] When the outer loop control is a grid-forming control, the command value of the negative sequence current under the outer loop control is calculated using the third calculation formula according to the outer loop control parameters of the power electronic equipment;

[0026] The third calculation formula is a Laplace transform formula of a transfer function of a grid-type controller of a negative-sequence current.

[0027] Preferably, the step of limiting the command values ​​of the positive and negative sequence currents, and performing vector fusion on the command values ​​of the limited positive and negative sequence currents to obtain the command values ​​of the positive and negative sequence currents after limiting the maximum values ​​comprises:

[0028] The positive-sequence d-axis current command value, the positive-sequence q-axis current command value, the negative-sequence d-axis current command value, and the negative-sequence q-axis current command value are respectively limited to obtain the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting;

[0029] Based on the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting, current vector fusion is performed using a current vector calculation formula to obtain a current vector;

[0030] According to the current vector, the preset maximum limiting current of the fault ride-through, the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting, a calculation formula for the positive and negative sequence current command values ​​after limiting the maximum value is adopted to calculate the positive-sequence d-axis current command value after limiting the maximum value, the positive-sequence q-axis current command value after limiting the maximum value, the negative-sequence d-axis current command value after limiting the maximum value, and the negative-sequence q-axis current command value after limiting the maximum value;

[0031] Among them, the calculation formulas for the positive and negative sequence current command values ​​after limiting the maximum value include one or more of the following: the calculation formula for the positive sequence d-axis current command value after limiting the maximum value, the calculation formula for the positive sequence q-axis current command value after limiting the maximum value, the calculation formula for the negative sequence d-axis current command value after limiting the maximum value and the calculation formula for the negative sequence q-axis current command value after limiting the maximum value.

[0032] Preferably, the positive and negative sequence currents are controlled according to the positive and negative sequence current command values ​​after limiting the maximum value to complete the low voltage ride through, including:

[0033] Based on the positive-sequence d-axis current command value after limiting the maximum value, the positive-sequence q-axis current command value after limiting the maximum value, the pre-obtained measured value of the positive-sequence d-axis current, and the pre-obtained measured value of the positive-sequence q-axis current, a positive-sequence d-axis voltage command value and a positive-sequence q-axis voltage command value are obtained through an inner-loop controller of the positive-sequence current to perform positive-sequence current control;

[0034] Based on the negative-sequence d-axis current command value after limiting the maximum value, the negative-sequence q-axis current command value after limiting the maximum value, the pre-obtained measured value of the negative-sequence d-axis current, and the pre-obtained measured value of the negative-sequence q-axis current, a negative-sequence d-axis voltage command value and a negative-sequence q-axis voltage command value are obtained through an inner-loop controller of the negative-sequence current to perform negative-sequence current control;

[0035] Low voltage ride-through is achieved through the positive sequence current control and the negative sequence current control.

[0036] Based on the same inventive concept, the patent application of the present invention also provides a low voltage ride-through control system for power electronic equipment, including: a positive and negative sequence current command value calculation module, a positive and negative sequence current command value limiting module and a low voltage ride-through module;

[0037] The positive and negative sequence current command value calculation module is used to set the control mode of the power electronic equipment to double closed-loop control; in the double closed-loop control mode, the command values ​​of the positive and negative sequence currents of the outer loop control are calculated according to the outer loop control parameters of the power electronic equipment;

[0038] The positive and negative sequence current command value limiting module is used to limit the command values ​​of the positive and negative sequence currents, and perform vector fusion on the command values ​​of the positive and negative sequence currents after the limit, so as to obtain the positive and negative sequence current command values ​​after the maximum value is limited;

[0039] The low voltage ride-through module is used to perform positive and negative sequence current control according to the positive and negative sequence current command values ​​after limiting the maximum value, so as to complete the low voltage ride-through.

[0040] Preferably, the dual closed-loop control includes an outer-loop control and an inner-loop control, the outer-loop control adopts a network-building type control or a network-following type control, and the inner-loop control adopts a constant current control.

[0041] Preferably, the positive and negative sequence current command values ​​include a positive sequence current command value and a negative sequence current command value; the positive and negative sequence current command value calculation module includes:

[0042] A positive-sequence current command value calculation submodule is used to calculate the command value of the positive-sequence current under the outer loop control according to the outer loop control parameters of the power electronic equipment and using the command value calculation formula of the positive-sequence current in the dual closed-loop control mode;

[0043] A negative-sequence current command value submodule, for calculating the command value of the negative-sequence current under the outer-loop control according to the outer-loop control parameters of the power electronic equipment and using a negative-sequence current command value calculation formula;

[0044] Among them, the outer loop control parameters include one or more of the following: the AC voltage d-axis measured value, the AC voltage q-axis measured value, the active power command value, the reactive power command value, the first proportional coefficient, the first integral coefficient, the Laplace operator, the second proportional coefficient and the second integral coefficient; the command value of the positive-sequence current is the positive-sequence d-axis current command value and the positive-sequence q-axis current command value; the command value of the negative-sequence current is the negative-sequence d-axis current command value and the negative-sequence q-axis current command value.

[0045] Preferably, the positive sequence current command value calculation submodule is specifically used for:

[0046] When the outer loop control is grid-following control, the first calculation formula is used to calculate the command value of the positive sequence current according to the double closed-loop control parameters;

[0047] When the outer loop control is a network-forming control, the second calculation formula is used to calculate the command value of the positive sequence current according to the double closed-loop control parameters;

[0048] The second calculation formula is a Laplace transform formula of the transfer function of the grid-type controller of the positive sequence current.

[0049] Preferably, the first calculation formula is as follows:

[0050]

[0051] Among them, i+ d is the positive sequence d-axis current command value, i+ q is the positive sequence q-axis current command value, u d is the measured value of the AC voltage q axis, p is the active power command value, u q The d-axis measured value of the AC voltage, and q is the reactive power command value.

[0052] Preferably, the second calculation formula is as follows:

[0053] G(S)=KP1+Ki1÷S

[0054] Among them, G(S) is the Laplace transform of the transfer function of the grid-type controller of the positive sequence current, KP1 is the first proportional coefficient, Ki1 is the first integral coefficient, and S is the Laplace operator.

[0055] Preferably, the negative sequence current command value calculation formula includes: a third calculation formula; the negative sequence current command value submodule is specifically used for:

[0056] When the outer loop control is grid-following control, the command value of the negative sequence current is set to 0;

[0057] When the outer loop control is a grid-forming control, the command value of the negative sequence current under the outer loop control is calculated using the third calculation formula according to the outer loop control parameters of the power electronic equipment;

[0058] The third calculation formula is a Laplace transform formula of a transfer function of a grid-type controller of a negative-sequence current.

[0059] Preferably, the module for limiting positive and negative sequence current command values ​​is used to:

[0060] The positive-sequence d-axis current command value, the positive-sequence q-axis current command value, the negative-sequence d-axis current command value, and the negative-sequence q-axis current command value are respectively limited to obtain the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting;

[0061] Based on the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting, current vector fusion is performed using a current vector calculation formula to obtain a current vector;

[0062] According to the current vector, the preset maximum limiting current of the fault ride-through, the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting, a calculation formula for the positive and negative sequence current command values ​​after limiting the maximum value is adopted to calculate the positive-sequence d-axis current command value after limiting the maximum value, the positive-sequence q-axis current command value after limiting the maximum value, the negative-sequence d-axis current command value after limiting the maximum value, and the negative-sequence q-axis current command value after limiting the maximum value;

[0063] Among them, the calculation formulas for the positive and negative sequence current command values ​​after limiting the maximum value include one or more of the following: the calculation formula for the positive sequence d-axis current command value after limiting the maximum value, the calculation formula for the positive sequence q-axis current command value after limiting the maximum value, the calculation formula for the negative sequence d-axis current command value after limiting the maximum value and the calculation formula for the negative sequence q-axis current command value after limiting the maximum value.

[0064] Preferably, the low voltage ride through module is used for:

[0065] Based on the positive-sequence d-axis current command value after limiting the maximum value, the positive-sequence q-axis current command value after limiting the maximum value, the pre-obtained measured value of the positive-sequence d-axis current, and the pre-obtained measured value of the positive-sequence q-axis current, a positive-sequence d-axis voltage command value and a positive-sequence q-axis voltage command value are obtained through an inner-loop controller of the positive-sequence current to perform positive-sequence current control;

[0066] Based on the negative-sequence d-axis current command value after limiting the maximum value, the negative-sequence q-axis current command value after limiting the maximum value, the pre-obtained measured value of the negative-sequence d-axis current, and the pre-obtained measured value of the negative-sequence q-axis current, a negative-sequence d-axis voltage command value and a negative-sequence q-axis voltage command value are obtained through an inner-loop controller of the negative-sequence current to perform negative-sequence current control;

[0067] Low voltage ride-through is achieved through the positive sequence current control and the negative sequence current control.

[0068] Based on the same inventive concept, the patent application of the present invention also provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0069] The memory is used to store one or more programs;

[0070] When the one or more programs are executed by the at least one processor, the aforementioned low voltage ride-through control method for power electronic equipment is implemented.

[0071] Based on the same inventive concept, the patent application of the present invention also provides a readable storage medium, on which a computer program is stored, and an execution program is stored. When the execution program is executed, a low voltage ride-through control method for power electronic equipment as described above is implemented.

[0072] Compared with the closest prior art, the patent application of this invention has the following beneficial effects:

[0073] The patent application of the present invention provides a low voltage ride-through control method and system for power electronic equipment, including: setting the control mode of the power electronic equipment to dual closed-loop control; in the dual closed-loop control mode, calculating the command values ​​of the positive and negative sequence currents of the outer loop control according to the outer loop control parameters of the power electronic equipment; limiting the command values ​​of the positive and negative sequence currents, and vector fusion of the command values ​​of the positive and negative sequence currents after the limit to obtain the positive and negative sequence current command values ​​after the maximum value is limited; according to the positive and negative sequence current command values ​​after the maximum value is limited, positive and negative sequence current control is performed to complete low voltage ride-through; the present invention can achieve fault current suppression based on the low voltage ride-through process by vector fusion of the command values ​​of the positive and negative sequence currents after the limit, avoid the generation of large overcurrent phenomena, thereby reducing the occurrence of tripping situations, and ensure that low voltage ride-through can be achieved with a high probability without affecting the normal control strategy logic. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 A schematic flow chart of a low voltage ride-through control method for power electronic equipment provided in the patent application of the present invention;

[0075] Figure 2 It is a structural diagram of a low voltage ride-through control system for power electronic equipment provided in the patent application of the present invention;

[0076] Figure 3 It is a schematic structural diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0077] The specific implementation methods of the patent application of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0078] Embodiment 1:

[0079] The present invention provides a method for controlling low voltage ride-through of power electronic equipment. Figure 1 As shown, including:

[0080] Step 1: Set the control mode of the power electronic equipment to dual closed-loop control;

[0081] Step 2: Under the dual closed-loop control mode, according to the outer loop control parameters of the power electronic equipment, the command values ​​of the positive and negative sequence currents of the outer loop control are calculated;

[0082] Step 3: limiting the command values ​​of the positive and negative sequence currents, and performing vector fusion on the command values ​​of the positive and negative sequence currents after the limiting, to obtain the positive and negative sequence current command values ​​after limiting the maximum values;

[0083] Step 4: According to the positive and negative sequence current command values ​​after limiting the maximum value, positive and negative sequence current control is performed to complete low voltage ride through.

[0084] In one implementation of step 1 above, the dual closed-loop control includes an outer-loop control and an inner-loop control, the outer-loop control adopts a network-building control or a network-following control, and the inner-loop control adopts a constant current control.

[0085] For example, the grid-forming control strategy is selected as VF (Volt frequency, voltage-frequency conversion) control, and the grid-following control strategy adopts PQ (active and reactive) control; it needs to be additionally explained that the control given values ​​of VF control are voltage and frequency; the given values ​​of PQ control are active power and reactive power; the present invention controls the inner and outer loops of the electronic power equipment respectively, and the inner loop control adopts constant current control, which is convenient for subsequent positive and negative sequence current control.

[0086] The positive and negative sequence current command values ​​in step 2 include the positive sequence current command value and the negative sequence current command value; in the dual closed-loop control mode, according to the outer loop control parameters of the power electronic equipment, the positive and negative sequence current command values ​​of the outer loop control are calculated, including:

[0087] In the dual closed-loop control mode, according to the outer loop control parameters of the power electronic equipment, the command value calculation formula of the positive sequence current is used to calculate the command value of the positive sequence current under the outer loop control;

[0088] According to the outer loop control parameters of the power electronic equipment, the command value of the negative sequence current is calculated using the command value calculation formula of the negative sequence current under the outer loop control;

[0089] Among them, the outer loop control parameters include one or more of the following: the AC voltage d-axis measured value, the AC voltage q-axis measured value, the active power command value, the reactive power command value, the first proportional coefficient, the first integral coefficient, the Laplace operator, the second proportional coefficient and the second integral coefficient; the command value of the positive-sequence current is the positive-sequence d-axis current command value and the positive-sequence q-axis current command value; the command value of the negative-sequence current is the negative-sequence d-axis current command value and the negative-sequence q-axis current command value.

[0090] In one implementation, the command value calculation formula of the positive sequence current includes a first calculation formula and a second calculation formula; the command value calculation formula of the positive sequence current is used to calculate the command value of the positive sequence current under the outer loop control according to the outer loop control parameter of the power electronic equipment, including:

[0091] When the outer loop control is grid-following control, the first calculation formula is used to calculate the command value of the positive sequence current according to the double closed-loop control parameters;

[0092] For example, when the outer loop control adopts the grid-following control, the command value of the positive sequence current is calculated using the first calculation formula, and the input quantity of the grid-following control is the positive sequence component of the AC side voltage. and negative sequence component

[0093] When the outer loop control is a network-forming control, the second calculation formula is used to calculate the command value of the positive sequence current according to the double closed-loop control parameters;

[0094] For example, when the outer loop control adopts the grid-type control, the command value of the positive sequence current is obtained through the output of the grid-type controller of the positive sequence current, the Laplace transform of the transfer function of the grid-type controller of the positive sequence current is the second calculation formula, and when the grid-type controller is a PI (Proportional Integral) controller, the parameters of the PI controller are determined by simulation testing, and the simulation process at least includes semi-physical simulation.

[0095] The second calculation formula is a Laplace transform formula of the transfer function of the grid-type controller of the positive sequence current.

[0096] In one implementation, the first calculation formula is as follows:

[0097]

[0098] Among them, i+ d is the positive sequence d-axis current command value, i+ q is the positive sequence q-axis current command value, u d is the measured value of the AC voltage q axis, p is the active power command value, u q The d-axis measured value of the AC voltage, and q is the reactive power command value.

[0099] In one implementation, the second calculation formula is as follows:

[0100] G(S)=KP1+Ki 1÷S

[0101] Among them, G(S) is the Laplace transform of the transfer function of the grid-type controller of the positive sequence current, KP1 is the first proportional coefficient, Ki1 is the first integral coefficient, and S is the Laplace operator.

[0102] In one implementation, the negative sequence current command value calculation formula includes: a third calculation formula; the calculation of the command value of the negative sequence current under the outer loop control using the command value calculation formula of the negative sequence current according to the outer loop control parameter of the power electronic equipment includes:

[0103] When the outer loop control is grid-following control, the command value of the negative sequence current is set to 0;

[0104] When the outer loop control is a grid-forming control, the command value of the negative sequence current under the outer loop control is calculated using the third calculation formula according to the outer loop control parameters of the power electronic equipment;

[0105] For example, when the outer loop control adopts the grid-type control, the corresponding parameters are set by the PI controller, and then the corresponding positive sequence component and negative sequence component are measured as input, and the command value of the negative sequence current is obtained by the output of the grid-type controller of the negative sequence current. The Laplace transform of the transfer function of the grid-type controller of the negative sequence current is the third calculation formula, and the third calculation formula is as follows:

[0106] G2(S)=KP2+Ki2÷S

[0107] Among them, G2(S) is the Laplace transform of the transfer function of the grid-type controller of the negative sequence current, KP2 is the second proportional coefficient, Ki2 is the second integral coefficient, and S is the Laplace operator;

[0108] Among them, the third calculation formula is the Laplace transform of the transfer function of the grid-type controller of the negative sequence current; under the dual closed-loop control mode, the present invention calculates the command values ​​of the positive and negative sequence currents of the outer loop control, providing basic data for subsequent limiting.

[0109] The step 3 described above limits the command values ​​of the positive and negative sequence currents, and performs vector fusion on the command values ​​of the limited positive and negative sequence currents to obtain the command values ​​of the positive and negative sequence currents after limiting the maximum values, including:

[0110] The positive-sequence d-axis current command value, the positive-sequence q-axis current command value, the negative-sequence d-axis current command value, and the negative-sequence q-axis current command value are respectively limited to obtain the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting;

[0111] For example, the limiting process includes two levels of limiting, specifically, the first level limiting and the second level limiting, after the first level limiting, the positive sequence d-axis current command value after limiting, the positive sequence q-axis current command value after limiting, the negative sequence d-axis current command value after limiting, and the negative sequence q-axis current command value after limiting are obtained;

[0112] The positive sequence d-axis current command value is limited as follows:

[0113]

[0114] in, is the positive-sequence d-axis current command value, L1 is the upper limit value of the positive-sequence current command value, and L2 is the lower limit value of the positive-sequence current command value;

[0115] The positive sequence q-axis current command value is limited as follows:

[0116]

[0117] in, is the positive-sequence q-axis current command value, L1 is the upper limit value of the positive-sequence current command value, and L2 is the lower limit value of the positive-sequence current command value;

[0118] Limit the negative sequence d-axis current command value:

[0119]

[0120] in, is the negative-sequence d-axis current command value, L3 is the upper limit of the negative-sequence current command value, and L4 is the lower limit of the negative-sequence current command value;

[0121] Limit the negative sequence q-axis current command value:

[0122]

[0123] in, is the negative-sequence q-axis current command value, L3 is the upper limit value of the negative-sequence current command value, and L4 is the lower limit value of the negative-sequence current command value;

[0124] When the command value before the amplitude limit in the positive sequence d-axis current command value, the positive sequence q-axis current command value, the negative sequence d-axis current command value or the negative sequence q-axis current command value exceeds the upper and lower limits, the outer loop controller limits its output selection to the limit value at the corresponding moment to the corresponding L1, L2, L3 or L4 at that time;

[0125] Based on the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting and the negative-sequence q-axis current command value after limiting, the positive-sequence current command value after limiting and the negative-sequence current command value after limiting are vector-fused by using a current vector calculation formula to obtain a current vector;

[0126] For example, the current vector is calculated as follows:

[0127]

[0128] Where img is the current vector, is the positive-sequence d-axis current command value after limiting, is the positive sequence q-axis current command value after limiting, is the negative-sequence d-axis current command value after limiting, It is the negative-sequence q-axis current command value after limiting.

[0129] According to the current vector, the preset maximum limiting current of the fault ride-through, the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting, a calculation formula for the positive and negative sequence current command values ​​after limiting the maximum value is adopted to calculate the positive-sequence d-axis current command value after limiting the maximum value, the positive-sequence q-axis current command value after limiting the maximum value, the negative-sequence d-axis current command value after limiting the maximum value, and the negative-sequence q-axis current command value after limiting the maximum value;

[0130] Among them, the calculation formulas for the positive and negative sequence current command values ​​after limiting the maximum value include one or more of the following: the calculation formula for the positive sequence d-axis current command value after limiting the maximum value, the calculation formula for the positive sequence q-axis current command value after limiting the maximum value, the calculation formula for the negative sequence d-axis current command value after limiting the maximum value and the calculation formula for the negative sequence q-axis current command value after limiting the maximum value.

[0131] For example, after the second level of limiting, the positive sequence d-axis current command value after limiting the maximum value, the positive sequence q-axis current command value after limiting the maximum value, the negative sequence d-axis current command value after limiting the maximum value and the negative sequence q-axis current command value after limiting the maximum value are obtained; for the positive sequence d-axis current command value Positive sequence q-axis current command value Negative sequence d-axis current command value Negative sequence q-axis current command value Perform amplitude limiting to generate a positive-sequence d-axis current command value after amplitude limiting, a positive-sequence q-axis current command value after amplitude limiting, a negative-sequence d-axis current command value after amplitude limiting, and a negative-sequence q-axis current command value after amplitude limiting as input variables of the inner loop control, thereby realizing comprehensive limiting of the command value that has been amplitude limited;

[0132] The calculation formula of the positive sequence d-axis current command value after limiting the maximum value is as follows:

[0133]

[0134] in, is the positive-sequence d-axis current command value after limiting the maximum value, is the positive sequence d-axis current command value after limiting, Imax is the maximum limiting current of fault crossing, and img is the current vector;

[0135] The calculation formula of the positive sequence q-axis current command value after limiting the maximum value is as follows:

[0136]

[0137] in, is the positive-sequence d-axis current command value after limiting the maximum value, is the positive sequence q-axis current command value after limiting, Imax is the maximum limiting current of fault crossing, and img is the current vector;

[0138] The calculation formula of the negative sequence d-axis current command value after limiting the maximum value is as follows:

[0139]

[0140] in, is the negative-sequence d-axis current command value after limiting the maximum value, is the negative-sequence d-axis current command value after limiting, Imax is the maximum limiting current of fault crossing, and img is the current vector;

[0141] The calculation formula of the negative sequence q-axis current command value after limiting the maximum value is as follows:

[0142]

[0143] in, is the negative sequence q-axis current command value after limiting the maximum value, is the negative-sequence q-axis current command value after limiting, Imax is the maximum limiting current of fault crossing, and img is the current vector; the present invention can realize fault current suppression based on the low voltage crossing process by vector fusion of the command values ​​of the positive and negative sequence currents after limiting, avoid the generation of large overcurrent phenomena, thereby reducing the occurrence of tripping situations, and ensure that low voltage crossing can be achieved with a high probability without affecting the normal control strategy logic; the present invention limits the positive and negative sequence current command values ​​separately on the basis of controlling the positive and negative sequence circuits, ensuring that during the execution process, both the positive and negative sequence control loops can achieve effective fault suppression.

[0144] The above step 4 performs positive and negative sequence current control according to the positive and negative sequence current command values ​​after limiting the maximum value to complete low voltage ride through, including:

[0145] Based on the positive-sequence d-axis current command value after limiting the maximum value, the positive-sequence q-axis current command value after limiting the maximum value, the pre-obtained measured value of the positive-sequence d-axis current, and the pre-obtained measured value of the positive-sequence q-axis current, a positive-sequence d-axis voltage command value and a positive-sequence q-axis voltage command value are obtained through an inner-loop controller of the positive-sequence current to perform positive-sequence current control;

[0146] For example, the positive sequence d-axis current command value after limiting the maximum value and the positive sequence q-axis current command value after limiting the maximum value are set as the given value of the inner loop controller of the positive sequence current, the measured value of the positive sequence d-axis current and the measured value of the positive sequence q-axis current are set as the measured value of the inner loop controller of the positive sequence current, and the positive sequence d-axis component of the AC side voltage is set as the positive sequence d-axis component of the AC side voltage. and the positive sequence q-axis component As the measured value of the inner loop controller of the positive sequence voltage, the Laplace transform of the transfer function of the inner loop controller of the positive sequence current is as follows:

[0147] G3(S)=KP3+Ki3÷S

[0148] Wherein, G3(S) is the third transfer function, KP3 is the third proportional coefficient, Ki3 is the third integral coefficient, and S is the Laplace operator;

[0149] By setting the transfer function of the inner loop current, the specific positive sequence current control based on the PI controller is completed.

[0150] Based on the negative-sequence d-axis current command value after limiting the maximum value, the negative-sequence q-axis current command value after limiting the maximum value, the pre-obtained measured value of the negative-sequence d-axis current, and the pre-obtained measured value of the negative-sequence q-axis current, a negative-sequence d-axis voltage command value and a negative-sequence q-axis voltage command value are obtained through an inner-loop controller of the negative-sequence current to perform negative-sequence current control;

[0151] For example, the negative-sequence d-axis current command value after limiting the maximum value and the negative-sequence q-axis current command value after limiting the maximum value are set as the given value of the inner loop controller of the negative-sequence current;

[0152] The measured value of the negative-sequence d-axis current and the measured value of the negative-sequence q-axis current are set as the measured values ​​of the inner loop controller of the negative-sequence current;

[0153] Will and As the measured value of the inner loop controller of the negative sequence current, the negative sequence voltage command values ​​of the d axis and the q axis are used as the output of the inner loop controller of the negative sequence current;

[0154] The Laplace transform of the transfer function of the inner loop controller for the negative sequence current is as follows:

[0155] G4(S)=KP4+Ki4÷S

[0156] Wherein, G4(S) is the fourth transfer function, KP4 is the fourth proportional coefficient, Ki4 is the fourth integral coefficient, and S is the Laplace operator;

[0157] By setting the transfer function of the inner loop current, the specific negative sequence current control based on the PI controller is completed.

[0158] Low voltage ride-through is achieved through the positive-sequence current control and the negative-sequence current control. The present invention performs positive and negative-sequence current control by limiting the positive and negative-sequence current command values ​​after the maximum value, and can quickly achieve low voltage ride-through.

[0159] Embodiment 2:

[0160] Based on the same inventive concept, the present invention patent application also provides a low voltage ride-through control system for power electronic equipment such as Figure 2 , including: a positive and negative sequence current command value calculation module, a positive and negative sequence current command value limiting module and a low voltage ride-through module;

[0161] The positive and negative sequence current command value calculation module is used to set the control mode of the power electronic equipment to double closed-loop control; in the double closed-loop control mode, the command values ​​of the positive and negative sequence currents of the outer loop control are calculated according to the outer loop control parameters of the power electronic equipment;

[0162] The positive and negative sequence current command value limiting module is used to limit the command values ​​of the positive and negative sequence currents, and perform vector fusion on the command values ​​of the positive and negative sequence currents after the limit, so as to obtain the positive and negative sequence current command values ​​after the maximum value is limited;

[0163] The low voltage ride-through module is used to perform positive and negative sequence current control according to the positive and negative sequence current command values ​​after limiting the maximum value, so as to complete the low voltage ride-through.

[0164] Preferably, the dual closed-loop control includes an outer-loop control and an inner-loop control, the outer-loop control adopts a network-building type control or a network-following type control, and the inner-loop control adopts a constant current control.

[0165] Preferably, the positive and negative sequence current command values ​​include a positive sequence current command value and a negative sequence current command value; the positive and negative sequence current command value calculation module includes:

[0166] A positive-sequence current command value calculation submodule is used to calculate the command value of the positive-sequence current under the outer loop control according to the outer loop control parameters of the power electronic equipment and using the command value calculation formula of the positive-sequence current in the dual closed-loop control mode;

[0167] A negative-sequence current command value submodule, for calculating the command value of the negative-sequence current under the outer-loop control according to the outer-loop control parameters of the power electronic equipment and using a negative-sequence current command value calculation formula;

[0168] Among them, the outer loop control parameters include one or more of the following: the AC voltage d-axis measured value, the AC voltage q-axis measured value, the active power command value, the reactive power command value, the first proportional coefficient, the first integral coefficient, the Laplace operator, the second proportional coefficient and the second integral coefficient; the command value of the positive-sequence current is the positive-sequence d-axis current command value and the positive-sequence q-axis current command value; the command value of the negative-sequence current is the negative-sequence d-axis current command value and the negative-sequence q-axis current command value.

[0169] Preferably, the positive sequence current command value calculation submodule is specifically used for:

[0170] When the outer loop control is grid-following control, the first calculation formula is used to calculate the command value of the positive sequence current according to the double closed-loop control parameters;

[0171] When the outer loop control is a network-forming control, the second calculation formula is used to calculate the command value of the positive sequence current according to the double closed-loop control parameters;

[0172] The second calculation formula is a Laplace transform formula of the transfer function of the grid-type controller of the positive sequence current.

[0173] Preferably, the first calculation formula is as follows:

[0174]

[0175] Among them, i+ d is the positive sequence d-axis current command value, i+ q is the positive sequence q-axis current command value, u d is the measured value of the AC voltage q axis, p is the active power command value, u q The d-axis measured value of the AC voltage, and q is the reactive power command value.

[0176] Preferably, the second calculation formula is as follows:

[0177] G(S)=KP1+Ki1÷S

[0178] Among them, G(S) is the Laplace transform of the transfer function of the grid-type controller of the positive sequence current, KP1 is the first proportional coefficient, Ki1 is the first integral coefficient, and S is the Laplace operator.

[0179] Preferably, the negative sequence current command value calculation formula includes: a third calculation formula; the negative sequence current command value submodule is specifically used for:

[0180] When the outer loop control is grid-following control, the command value of the negative sequence current is set to 0;

[0181] When the outer loop control is a grid-forming control, the command value of the negative sequence current under the outer loop control is calculated using the third calculation formula according to the outer loop control parameters of the power electronic equipment;

[0182] The third calculation formula is a Laplace transform formula of a transfer function of a grid-type controller of a negative-sequence current.

[0183] Preferably, the module for limiting positive and negative sequence current command values ​​is used to:

[0184] The positive-sequence d-axis current command value, the positive-sequence q-axis current command value, the negative-sequence d-axis current command value, and the negative-sequence q-axis current command value are respectively limited to obtain the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting;

[0185] Based on the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting, current vector fusion is performed using a current vector calculation formula to obtain a current vector;

[0186] According to the current vector, the preset maximum limiting current of the fault ride-through, the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting, a calculation formula for the positive and negative sequence current command values ​​after limiting the maximum value is adopted to calculate the positive-sequence d-axis current command value after limiting the maximum value, the positive-sequence q-axis current command value after limiting the maximum value, the negative-sequence d-axis current command value after limiting the maximum value, and the negative-sequence q-axis current command value after limiting the maximum value;

[0187] Among them, the calculation formulas for the positive and negative sequence current command values ​​after limiting the maximum value include one or more of the following: the calculation formula for the positive sequence d-axis current command value after limiting the maximum value, the calculation formula for the positive sequence q-axis current command value after limiting the maximum value, the calculation formula for the negative sequence d-axis current command value after limiting the maximum value and the calculation formula for the negative sequence q-axis current command value after limiting the maximum value.

[0188] Preferably, the low voltage ride through module is used for:

[0189] Based on the positive-sequence d-axis current command value after limiting the maximum value, the positive-sequence q-axis current command value after limiting the maximum value, the pre-obtained measured value of the positive-sequence d-axis current, and the pre-obtained measured value of the positive-sequence q-axis current, a positive-sequence d-axis voltage command value and a positive-sequence q-axis voltage command value are obtained through an inner-loop controller of the positive-sequence current to perform positive-sequence current control;

[0190] Based on the negative-sequence d-axis current command value after limiting the maximum value, the negative-sequence q-axis current command value after limiting the maximum value, the pre-obtained measured value of the negative-sequence d-axis current, and the pre-obtained measured value of the negative-sequence q-axis current, a negative-sequence d-axis voltage command value and a negative-sequence q-axis voltage command value are obtained through an inner-loop controller of the negative-sequence current to perform negative-sequence current control;

[0191] Low voltage ride-through is achieved through the positive sequence current control and the negative sequence current control.

[0192] Example 3

[0193] like Figure 3 As shown, the present invention also provides an electronic device, which may be a computer device, a single-chip device, an intelligent mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected via a bus; the memory may be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory may also be used to store data, which may be called and / or modified when the instructions are executed.

[0194] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in a storage medium to implement a corresponding method flow or a corresponding function, so as to implement the steps of a low voltage ride-through control method for power electronic equipment in the above-mentioned embodiment.

[0195] Example 4

[0196] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in an electronic device for storing programs and data. It can be understood that the storage medium here can include both built-in storage media in electronic devices and, of course, extended storage media supported by electronic devices. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by a processor are also stored in the storage space, and these instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of a low voltage ride-through control method for power electronic equipment in the above embodiment.

[0197] It should be understood by those skilled in the art that the embodiments of the present invention patent application can be provided as methods, systems, or computer program products. Therefore, the present invention patent application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention patent application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0198] The present invention patent application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present invention patent application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0199] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0200] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0201] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the patent application of the present invention rather than to limit its protection scope. Although the patent application of the present invention is described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the patent application of the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims to be approved.

Claims

1. A low voltage ride-through control method for power electronic equipment, characterized in that: include: Set the control mode of the power electronic equipment to double closed-loop control; In the dual closed-loop control mode, according to the outer loop control parameters of the power electronic equipment, the command values ​​of the positive and negative sequence currents of the outer loop control are calculated; Limiting the command values ​​of the positive and negative sequence currents, and performing vector fusion on the command values ​​of the positive and negative sequence currents after the limiting, to obtain the positive and negative sequence current command values ​​after limiting the maximum values; According to the positive and negative sequence current command values ​​after limiting the maximum value, positive and negative sequence current control is performed to complete low voltage ride through.

2. The method according to claim 1, characterized in that The dual closed-loop control includes an outer loop control and an inner loop control, wherein the outer loop control adopts a network-building type control or a network-following type control, and the inner loop control adopts a constant current control.

3. The method according to claim 2, characterized in that The command values ​​of the positive and negative sequence currents include a command value of the positive sequence current and a command value of the negative sequence current; In the dual closed-loop control mode, according to the outer loop control parameters of the power electronic equipment, the command values ​​of the positive and negative sequence currents of the outer loop control are calculated, including: In the dual closed-loop control mode, according to the outer loop control parameters of the power electronic equipment, the command value calculation formula of the positive sequence current is used to calculate the command value of the positive sequence current under the outer loop control; According to the outer loop control parameters of the power electronic equipment, the command value of the negative sequence current is calculated using the command value calculation formula of the negative sequence current under the outer loop control; Among them, the outer loop control parameters include one or more of the following: the AC voltage d-axis measured value, the AC voltage q-axis measured value, the active power command value, the reactive power command value, the first proportional coefficient, the first integral coefficient, the Laplace operator, the second proportional coefficient and the second integral coefficient; the command value of the positive-sequence current is the positive-sequence d-axis current command value and the positive-sequence q-axis current command value; the command value of the negative-sequence current is the negative-sequence d-axis current command value and the negative-sequence q-axis current command value.

4. The method according to claim 3, characterized in that The command value calculation formula of the positive sequence current includes a first calculation formula and a second calculation formula; the command value calculation formula of the positive sequence current is used to calculate the command value of the positive sequence current under the outer loop control according to the outer loop control parameter of the power electronic equipment, including: When the outer loop control is grid-following control, the first calculation formula is used to calculate the command value of the positive sequence current according to the double closed-loop control parameters; When the outer loop control is a network-forming control, the second calculation formula is used to calculate the command value of the positive sequence current according to the double closed-loop control parameters; The second calculation formula is a Laplace transform formula of a transfer function of a grid-type controller of a positive-sequence current.

5. The method according to claim 4, characterized in that The first calculation formula is as follows: Among them, i+ d is the positive sequence d-axis current command value, i+ q is the positive sequence q-axis current command value, u d is the measured value of the AC voltage q axis, p is the active power command value, u q The d-axis measured value of the AC voltage, and q is the reactive power command value.

6. The method according to claim 4, characterized in that The second calculation formula is as follows: G(S)=KP1+Ki1÷S Among them, G(S) is the Laplace transform of the transfer function of the grid-type controller of the positive sequence current, KP1 is the first proportional coefficient, Ki1 is the first integral coefficient, and S is the Laplace operator.

7. The method according to claim 3, characterized in that The negative sequence current command value calculation formula includes: a third calculation formula; the negative sequence current command value calculation formula is used according to the outer loop control parameter of the power electronic equipment to calculate the negative sequence current command value under the outer loop control, including: When the outer loop control is grid-following control, the command value of the negative sequence current is set to 0; When the outer loop control is a grid-forming control, the third calculation formula is used to calculate the command value of the negative sequence current under the outer loop control according to the outer loop control parameters of the power electronic equipment; The third calculation formula is a Laplace transform formula of a transfer function of a grid-type controller of a negative-sequence current.

8. The method according to claim 3, characterized in that The step of limiting the command values ​​of the positive and negative sequence currents and performing vector fusion on the command values ​​of the limited positive and negative sequence currents to obtain the command values ​​of the positive and negative sequence currents after limiting the maximum values ​​includes: The positive-sequence d-axis current command value, the positive-sequence q-axis current command value, the negative-sequence d-axis current command value, and the negative-sequence q-axis current command value are respectively limited to obtain the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting; Based on the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting, current vector fusion is performed using a current vector calculation formula to obtain a current vector; According to the current vector, the preset maximum limiting current of the fault ride-through, the positive-sequence d-axis current command value after limiting, the positive-sequence q-axis current command value after limiting, the negative-sequence d-axis current command value after limiting, and the negative-sequence q-axis current command value after limiting, a calculation formula for the positive and negative sequence current command values ​​after limiting the maximum value is adopted to calculate the positive-sequence d-axis current command value after limiting the maximum value, the positive-sequence q-axis current command value after limiting the maximum value, the negative-sequence d-axis current command value after limiting the maximum value, and the negative-sequence q-axis current command value after limiting the maximum value; Among them, the calculation formulas for the positive and negative sequence current command values ​​after limiting the maximum value include one or more of the following: the calculation formula for the positive sequence d-axis current command value after limiting the maximum value, the calculation formula for the positive sequence q-axis current command value after limiting the maximum value, the calculation formula for the negative sequence d-axis current command value after limiting the maximum value and the calculation formula for the negative sequence q-axis current command value after limiting the maximum value.

9. The method according to claim 6, characterized in that The positive and negative sequence currents are controlled according to the positive and negative sequence current command values ​​after limiting the maximum value to complete the low voltage ride through, including: Based on the positive-sequence d-axis current command value after limiting the maximum value, the positive-sequence q-axis current command value after limiting the maximum value, the pre-obtained measured value of the positive-sequence d-axis current, and the pre-obtained measured value of the positive-sequence q-axis current, a positive-sequence d-axis voltage command value and a positive-sequence q-axis voltage command value are obtained through an inner-loop controller of the positive-sequence current to perform positive-sequence current control; Based on the negative-sequence d-axis current command value after limiting the maximum value, the negative-sequence q-axis current command value after limiting the maximum value, the pre-obtained measured value of the negative-sequence d-axis current, and the pre-obtained measured value of the negative-sequence q-axis current, a negative-sequence d-axis voltage command value and a negative-sequence q-axis voltage command value are obtained through an inner-loop controller of the negative-sequence current to perform negative-sequence current control; Low voltage ride-through is achieved through the positive sequence current control and the negative sequence current control.

10. A low voltage ride-through control system for power electronic equipment, characterized in that: include: Control mode setting module, positive and negative sequence current command value calculation module, positive and negative sequence current command value limiting module and low voltage ride through module; The control mode setting module is used to set the control mode of the power electronic equipment to dual closed-loop control; The positive and negative sequence current command value calculation module is used to calculate the command values ​​of the positive and negative sequence current of the outer loop control according to the outer loop control parameters of the power electronic equipment in the dual closed-loop control mode; The positive and negative sequence current command value limiting module is used to limit the command values ​​of the positive and negative sequence currents, and perform vector fusion on the command values ​​of the positive and negative sequence currents after the limit, so as to obtain the positive and negative sequence current command values ​​after limiting the maximum value; The low voltage ride-through module is used to perform positive and negative sequence current control according to the positive and negative sequence current command values ​​after limiting the maximum value, so as to complete the low voltage ride-through.

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