Power electronic equipment low voltage ride through control method and device

Abstract

The invention provides a power electronic equipment low voltage ride through control method and device. The low-voltage ride-through control method for the power electronic equipment comprises the steps that the voltage of the power electronic equipment is acquired, and the voltage of the power electronic equipment comprises the positive sequence voltage and the negative sequence voltage; carrying out amplitude limiting on the voltage based on a preset amplitude limiting range to obtain the voltage after initial amplitude limiting; and performing composite vector amplitude limiting on the voltage after the initial amplitude limiting based on a preset maximum amplitude limiting value to obtain a voltage after the composite vector amplitude limiting. According to the invention, voltage distortion and relatively high harmonic current can be avoided, so that the effects of harmonic current suppression and distortion suppression are realized.

Description

Technical Field

[0001] The present application relates to the field of power electronic control, and in particular to a method and device for controlling low voltage ride-through of power electronic equipment. Background Art

[0002] With the widespread application of power electronic equipment, the stability and reliability of power electronic equipment are becoming more and more important. As an important indicator to measure the performance of power electronic equipment, low voltage ride-through capability is receiving great attention. Since power grid fluctuations or failures may cause voltage drops, power electronic equipment with low voltage ride-through capability can maintain stable operation when the voltage is abnormal, avoiding equipment damage or data loss. Therefore, improving the low voltage ride-through capability of power electronic equipment is of great significance to ensuring equipment stability and improving system reliability.

[0003] In the prior art, high voltage fluctuations are often generated during low voltage ride-through of power electronic equipment, and extremely high harmonic currents are also generated. Summary of the invention

[0004] In order to solve the problem in the prior art that high voltage fluctuation, voltage distortion and high harmonic current are generated during low voltage ride-through of power electronic equipment, the present application provides a low voltage ride-through control method and device for power electronic equipment.

[0005] On the one hand, the present application proposes a low voltage ride-through control method for power electronic equipment, which control method may include: obtaining the voltage of the power electronic equipment, the voltage of the power electronic equipment includes a positive sequence voltage and a negative sequence voltage; based on a preset limiting range, limiting the voltage to obtain the voltage after the initial limiting; based on a preset maximum limiting value, performing composite vector limiting on the voltage after the initial limiting to obtain the voltage after composite vector limiting.

[0006] Optionally, the limiting range includes a positive-sequence voltage limiting range and a negative-sequence voltage limiting range; based on the preset limiting range, the voltage is limited to obtain the voltage after the initial limiting step, including: according to the positive-sequence voltage limiting range, the positive-sequence voltage is limited to within the positive-sequence voltage limiting range, and the positive-sequence voltage after the initial limiting is obtained; according to the negative-sequence voltage limiting range, the negative-sequence voltage is limited to within the negative-sequence voltage limiting range, and the negative-sequence voltage after the initial limiting is obtained.

[0007] Optionally, the minimum value of the positive-sequence voltage limiting range is the first positive-sequence limiting value, and the maximum value of the positive-sequence voltage limiting range is the second positive-sequence limiting value; according to the positive-sequence voltage limiting range, the positive-sequence voltage is limited to within the positive-sequence voltage limiting range, and the step of obtaining the positive-sequence voltage after initial limiting includes: when the positive-sequence voltage is less than the first positive-sequence limiting value, the first positive-sequence limiting value is determined as the positive-sequence voltage after initial limiting; when the positive-sequence voltage is greater than or equal to the first positive-sequence limiting value and less than or equal to the second positive-sequence limiting value, the positive-sequence voltage is determined as the positive-sequence voltage after initial limiting; when the positive-sequence voltage is greater than the second positive-sequence limiting value, the second positive-sequence limiting value is determined as the positive-sequence voltage after initial limiting.

[0008] Optionally, the minimum value of the negative-sequence voltage limiting range is the first negative-sequence limiting value, and the maximum value of the negative-sequence voltage limiting range is the second negative-sequence limiting value; according to the negative-sequence voltage limiting range, the negative-sequence voltage is limited to within the negative-sequence voltage limiting range, and the step of obtaining the negative-sequence voltage after initial limiting includes: when the negative-sequence voltage is less than the first negative-sequence limiting value, the first negative-sequence limiting value is determined as the negative-sequence voltage after initial limiting; when the negative-sequence voltage is greater than or equal to the first negative-sequence limiting value and less than or equal to the second negative-sequence limiting value, the negative-sequence voltage is determined as the negative-sequence voltage after initial limiting; when the negative-sequence voltage is greater than the second negative-sequence limiting value, the second negative-sequence limiting value is determined as the negative-sequence voltage after initial limiting.

[0009] Optionally, based on a preset maximum limiting value, composite vector limiting is performed on the voltage after initial limiting to obtain the voltage after composite vector limiting, comprising: performing composite vector limiting on the positive sequence voltage after initial limiting according to the maximum limiting value, the positive sequence voltage after initial limiting and the negative sequence voltage after initial limiting to obtain the positive sequence voltage after composite vector limiting; performing composite vector limiting on the negative sequence voltage after initial limiting according to the maximum limiting value, the positive sequence voltage after initial limiting and the negative sequence voltage after initial limiting to obtain the negative sequence voltage after composite vector limiting.

[0010] Optionally, the positive sequence voltage after the initial limiting includes the Q axis positive sequence voltage after the initial limiting and the D axis positive sequence voltage after the initial limiting, and the negative sequence voltage after the initial limiting includes the Q axis negative sequence voltage after the initial limiting and the D axis negative sequence voltage after the initial limiting; and the step of performing composite vector limiting on the positive sequence voltage after the initial limiting according to the maximum limiting value, the positive sequence voltage after the initial limiting and the negative sequence voltage after the initial limiting to obtain the positive sequence voltage after composite vector limiting includes:

[0011] The limiting proportional coefficient is calculated using the Q-axis positive sequence voltage after the initial limiting, the D-axis positive sequence voltage after the initial limiting, the Q-axis negative sequence voltage after the initial limiting, and the D-axis negative sequence voltage after the initial limiting. The limiting proportional coefficient satisfies:

[0012]

[0013] Where V mag represents the limiting ratio coefficient, Indicates the positive sequence voltage of the D axis after the initial limiting. is the Q-axis positive sequence voltage after the initial limiting, is the negative sequence voltage of the D axis after the initial limiting, is the Q-axis negative sequence voltage after the initial limiting;

[0014] The D-axis positive sequence voltage after composite vector limiting is calculated using the maximum limiting value, limiting ratio coefficient and D-axis positive sequence voltage after initial limiting. The D-axis positive sequence voltage after composite vector limiting satisfies the following relationship with the D-axis positive sequence voltage after initial limiting:

[0015]

[0016] In the formula, Represents the D-axis positive sequence voltage after composite vector limiting, V max Indicates the maximum limit value;

[0017] The Q-axis positive sequence voltage after composite vector limiting is calculated using the maximum limiting value, limiting ratio coefficient and the Q-axis positive sequence voltage after initial limiting. The Q-axis positive sequence voltage after composite vector limiting satisfies the following relationship with the Q-axis positive sequence voltage after initial limiting:

[0018]

[0019] In the formula, Represents the Q-axis positive sequence voltage after composite vector limiting.

[0020] Optionally, the step of performing composite vector limiting on the negative sequence voltage after the initial limiting according to the maximum limiting value, the positive sequence voltage after the initial limiting, and the negative sequence voltage after the initial limiting to obtain the negative sequence voltage after the composite vector limiting includes:

[0021] The Q-axis negative sequence voltage after composite vector limiting is calculated using the maximum limiting value, limiting ratio coefficient and the Q-axis negative sequence voltage after initial limiting. The Q-axis negative sequence voltage after composite vector limiting satisfies the following relationship with the Q-axis negative sequence voltage after initial limiting:

[0022]

[0023] In the formula, It represents the negative sequence voltage of D axis after the composite vector is limited;

[0024] The D-axis negative sequence voltage after composite vector limiting is calculated using the maximum limiting value, limiting ratio coefficient and the D-axis negative sequence voltage after initial limiting. The D-axis negative sequence voltage after composite vector limiting satisfies the following relationship with the D-axis negative sequence voltage after initial limiting:

[0025]

[0026] In the formula, Represents the Q-axis negative sequence voltage after composite vector limiting.

[0027] Optionally, the step of obtaining the voltage of the power electronic equipment includes: performing inner-loop positive-sequence current control on the positive-sequence input to obtain a Q-axis positive-sequence voltage and a D-axis positive-sequence voltage, wherein the positive-sequence input includes an initial Q-axis positive-sequence current, an initial D-axis positive-sequence current, an actually measured value of the Q-axis positive-sequence current, an actually measured value of the D-axis positive-sequence current, a grid-side positive-sequence voltage, and a grid-side negative-sequence voltage; performing inner-loop negative-sequence current control on the negative-sequence input to obtain a Q-axis negative-sequence voltage and a D-axis negative-sequence voltage, wherein the negative-sequence input includes a Q-axis negative-sequence current, a D-axis negative-sequence current, an actually measured value of the Q-axis negative-sequence current, an actually measured value of the D-axis negative-sequence current, a grid-side positive-sequence voltage, and a grid-side negative-sequence voltage.

[0028] Optionally, after the step of performing composite vector limiting on the voltage after initial limiting based on a preset maximum limiting value to obtain the composite vector limited voltage, the control method further comprises: performing coordinate system conversion on the composite vector limited voltage to obtain a voltage command value.

[0029] On the other hand, the present application also provides a low voltage ride-through control device for power electronic equipment, characterized in that the control device includes: an acquisition module for acquiring the voltage of the power electronic equipment, the voltage of the power electronic equipment including a positive sequence voltage and a negative sequence voltage; a first limiting module for limiting the voltage based on a preset limiting range to obtain the voltage after the initial limiting; a second limiting module for limiting the voltage after the initial limiting based on a preset maximum limiting value to obtain the voltage after composite vector limiting.

[0030] Compared with the prior art, the beneficial effects of this application are:

[0031] The low voltage ride-through control method of power electronic equipment provided in the present application obtains the voltage of the power electronic equipment, limits the voltage based on a preset limit range, and obtains the voltage after the initial limit; based on a preset maximum limit value, performs composite vector limit on the voltage after the initial limit, and obtains the voltage after the composite vector limit. It can be seen that after obtaining the voltage of the power electronic equipment, the present application first limits the voltage, and then performs a recheck vector limit on the voltage after the initial limit. That is to say, in the present application, the voltage of the power electronic equipment is limited twice, thereby improving the voltage fluctuation during the low voltage ride-through process, thereby avoiding the generation of voltage distortion and higher harmonic current, and further achieving the effect of harmonic current suppression and distortion suppression.

[0032] The low voltage ride-through control device for power electronic equipment provided in the present application includes an acquisition module for acquiring the voltage of the power electronic equipment; a first limiting module for limiting the voltage based on a preset limiting range to obtain the voltage after the initial limiting; and a second limiting module for limiting the voltage after the initial limiting based on a preset maximum limiting value to obtain the voltage after composite vector limiting. By acquiring the voltage of the power electronic equipment, the voltage is limited based on a preset limiting range to obtain the voltage after the initial limiting; and the voltage after the initial limiting is subjected to composite vector limiting based on a preset maximum limiting value to obtain the voltage after composite vector limiting. It can be seen that after obtaining the voltage of the power electronic equipment, the present application first limits the voltage, and then verifies the vector limiting of the voltage after the initial limiting. That is, in the present application, the voltage of the power electronic equipment is limited twice, thereby improving the voltage fluctuation during the low voltage ride-through process, thereby avoiding the generation of voltage distortion and higher harmonic current, and thus achieving the effect of harmonic current suppression and distortion suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of a flow chart of a low voltage ride-through control method for power electronic equipment in an embodiment of the present application;

[0034] Figure 2 for Figure 1 Specific flow diagram of step S20;

[0035] Figure 3 for Figure 1 Specific flow diagram of step S30;

[0036] Figure 4 for Figure 3 Specific flow diagram of step S31;

[0037] Figure 5 for Figure 3 Specific flow diagram of step S32;

[0038] Figure 6 for Figure 1 Specific flow diagram of step S10;

[0039] Figure 7 Another schematic diagram of a low voltage ride-through control method for power electronic equipment in an embodiment of the present application;

[0040] Figure 8 for Figure 1 Specific flow diagram of step S40;

[0041] Fig. 9 A schematic diagram of a structure of a low voltage ride through control device for power electronic equipment in an embodiment of the present application;

[0042] Fig.10 It is a schematic diagram of the structure of a computer device in an embodiment of the present application. DETAILED DESCRIPTION

[0043] Embodiment 1:

[0044] In order to solve the problem of high voltage fluctuation, voltage distortion and high harmonic current generated during low voltage ride-through of power electronic equipment in the prior art, such as Figure 1 As shown, this embodiment provides a low voltage ride-through control method for power electronic equipment. The control method may include:

[0045] S10, obtaining the voltage of the power electronic equipment.

[0046] Before obtaining the voltage of the power electronic equipment, a control mode may be preset, for example, the control mode may include an inner loop current control mode, or the control mode may include an inner loop current control mode and an outer loop current control mode. The voltage of the power electronic equipment includes a positive sequence voltage and a negative sequence voltage. The inner loop current control mode includes a positive sequence current control and a negative sequence current control.

[0047] In power electronic equipment, the input mode of the input quantity of the inner loop current control can be pre-set or the output of the outer loop current control mode. Here, the outer loop current control mode can be a grid-following outer loop control mode or a grid-forming outer loop control mode. In this embodiment, the input mode of the input quantity of the inner loop current control can be one of the above three modes, thereby achieving more accurate and efficient current control, thereby improving the stability and other performances of the power system where the power electronic equipment is located.

[0048] S20, based on a preset limiting range, limiting the voltage to obtain a voltage after initial limiting.

[0049] The limiting range may be a range pre-set according to actual working requirements of the power electronic equipment. Based on the range, the voltage may be initially limited and the voltage after the initial limiting may be obtained.

[0050] S30, performing composite vector limiting on the voltage after initial limiting based on a preset maximum limiting value to obtain a composite vector limited voltage.

[0051] The maximum limit value may be a maximum value pre-set according to the actual working requirements of the power electronic equipment. Based on the maximum limit value, the voltage after the initial limiting may be subjected to composite vector limiting, that is, secondary limiting may be performed to obtain the voltage after composite vector limiting.

[0052] Compared with the prior art, the beneficial effects of the embodiments of the present application are:

[0053] The low voltage ride-through control method for power electronic equipment provided in the embodiment of the present application obtains the voltage of the power electronic equipment, limits the voltage based on a preset limit range, and obtains the voltage after the initial limit; based on a preset maximum limit value, performs composite vector limit on the voltage after the initial limit, and obtains the voltage after the composite vector limit. It can be seen that after obtaining the voltage of the power electronic equipment, the present application first limits the voltage, and then performs a recheck vector limit on the voltage after the initial limit. That is to say, in the present application, the voltage of the power electronic equipment is limited twice, thereby improving the voltage fluctuation during the low voltage ride-through process, thereby avoiding the generation of voltage distortion and higher harmonic current, and further achieving the effect of harmonic current suppression and distortion suppression.

[0054] Optionally, the voltage of the power electronic equipment includes a positive sequence voltage and a negative sequence voltage, and the limit range includes a positive sequence voltage limit range and a negative sequence voltage limit range, wherein both the positive sequence voltage limit range and the negative sequence voltage limit range can be pre-set according to the actual working requirements of the power electronic equipment.

[0055] like Figure 2 As shown above Figure 1 The process step S20 shown in the figure limits the voltage based on the preset limiting range to obtain the voltage after the initial limiting, including:

[0056] S21, according to the positive sequence voltage limiting range, limiting the positive sequence voltage to within the positive sequence voltage limiting range, and obtaining the positive sequence voltage after the initial limiting.

[0057] That is to say, in this embodiment, the positive-sequence voltage after the initial amplitude limiting is within the positive-sequence voltage amplitude limiting range.

[0058] S22, according to the negative sequence voltage limiting range, limiting the negative sequence voltage to within the negative sequence voltage limiting range, and obtaining the negative sequence voltage after the initial limiting.

[0059] That is to say, in this embodiment, the negative sequence voltage after the initial amplitude limiting is within the negative sequence voltage amplitude limiting range.

[0060] Therefore, this embodiment limits the positive sequence voltage to a preset positive sequence voltage limit range, and limits the negative sequence voltage to a preset negative sequence voltage limit range, thereby preventing the positive sequence voltage from being too high or too low, thereby affecting the reliability of the power electronic equipment.

[0061] Optionally, the minimum value of the positive sequence voltage limit range is the first positive sequence limit value, the maximum value of the positive sequence voltage limit range is the second positive sequence limit value, and the second positive sequence limit value is greater than the first positive sequence limit value. For example, the first positive sequence limit value may be -1.2 times the per-unit value, and the second positive sequence limit value may be 1.2 times the per-unit value.

[0062] Above Figure 2 The process step S21 shown in the figure, according to the positive sequence voltage limiting range, limits the positive sequence voltage to within the positive sequence voltage limiting range, and obtains the positive sequence voltage after the initial limiting, including:

[0063] When the positive sequence voltage is less than the first positive sequence limit value, the first positive sequence limit value is determined as the positive sequence voltage after the initial limit. When the positive sequence voltage is greater than or equal to the first positive sequence limit value, and less than or equal to the second positive sequence limit value, the positive sequence voltage is determined as the positive sequence voltage after the initial limit. When the positive sequence voltage is greater than the second positive sequence limit value, the second positive sequence limit value is determined as the positive sequence voltage after the initial limit. In this way, the positive sequence voltage can be limited to between the first positive sequence limit value and the second positive sequence limit value.

[0064] It can be seen that in this embodiment, when the positive sequence voltage exceeds the positive sequence voltage limiting range, the positive sequence voltage can be limited, and it can be limited to between the first positive sequence limiting value and the second positive sequence limiting value, ensuring that the positive sequence voltage after the initial limiting does not exceed the set limiting value. In this way, the voltage of the power system where the power electronic equipment is located can be avoided to be too high or too low, thereby protecting the power system from the influence of too high or too low voltage, ensuring the stable operation of the power system and avoiding the voltage from exceeding the safety range, thereby improving the stability and reliability of the power system. Moreover, by limiting the positive sequence voltage in this way, the power system can better adapt to different operating conditions and environmental requirements.

[0065] In addition, the positive sequence voltage may include the Q axis positive sequence voltage and the D axis positive sequence voltage. Assuming that the first positive sequence amplitude limit value is L1 and the second positive sequence amplitude limit value is L2, the Q axis positive sequence voltage after the initial amplitude limit is U Q+ Satisfy: L1 ≥ U Q+ ≥L2. D-axis positive sequence voltage U after initial limiting D+ Also satisfies: L1≥U D+ ≥L2.

[0066] Optionally, the minimum value of the negative sequence voltage limit range is a first negative sequence limit value, the maximum value of the negative sequence voltage limit range is a second negative sequence limit value, and the second negative sequence limit value is greater than the first negative sequence limit value.

[0067] Above Figure 2 The process step S22 shown in the figure limits the negative sequence voltage to within the negative sequence voltage limiting range according to the negative sequence voltage limiting range, and obtains the negative sequence voltage after the initial limiting, including:

[0068] When the negative sequence voltage is less than the first negative sequence limit value, the first negative sequence limit value is determined as the negative sequence voltage after the initial limit. When the negative sequence voltage is greater than or equal to the first negative sequence limit value and less than or equal to the second negative sequence limit value, the negative sequence voltage is determined as the negative sequence voltage after the initial limit. When the negative sequence voltage is greater than the second negative sequence limit value, the second negative sequence limit value is determined as the negative sequence voltage after the initial limit. Thus, the negative sequence voltage can be limited to between the first negative sequence limit value and the second negative sequence limit value.

[0069] It can be seen that in this embodiment, when the negative sequence voltage exceeds the negative sequence voltage limiting range, the negative sequence voltage can be limited, and it can be limited to between the first negative sequence limiting value and the second negative sequence limiting value, ensuring that the negative sequence voltage after the initial limiting does not exceed the set limiting value. In this way, the voltage of the power system where the power electronic equipment is located can be avoided to be too high or too low, thereby protecting the power system from the influence of too high or too low voltage, ensuring the stable operation of the power system and avoiding the voltage from exceeding the safety range, thereby improving the stability and reliability of the power system. Moreover, by limiting the negative sequence voltage in this way, the power system can better adapt to different operating conditions and environmental requirements.

[0070] In addition, the negative sequence voltage may include the Q axis negative sequence voltage and the D axis negative sequence voltage. Assuming that the first negative sequence amplitude limit value is L3 and the second negative sequence amplitude limit value is L4, the Q axis negative sequence voltage U after the initial amplitude limit is Q- Satisfy: L3 ≥ U Q- ≥L4. D-axis negative sequence voltage U after initial limiting D- Also satisfies: L3 ≥ U D- ≥L4.

[0071] Alternatively, if Figure 3 As shown above Figure 1 The process step S30 shown in the figure performs composite vector limiting on the voltage after the initial limiting based on the preset maximum limiting value to obtain the voltage after the composite vector limiting, including:

[0072] S31, performing composite vector limiting on the positive sequence voltage after the initial limiting according to the maximum limiting value, the positive sequence voltage after the initial limiting, and the negative sequence voltage after the initial limiting, to obtain the positive sequence voltage after the composite vector limiting.

[0073] S32, performing composite vector limiting on the negative sequence voltage after the initial limiting according to the maximum limiting value, the positive sequence voltage after the initial limiting, and the negative sequence voltage after the initial limiting, to obtain the negative sequence voltage after the composite vector limiting.

[0074] In this way, when composite vector limiting is performed on the positive sequence voltage after initial limiting, the positive sequence voltage after initial limiting and the negative sequence voltage after initial limiting are fully considered, thereby enabling the composite vector limiting of the positive sequence voltage after initial limiting and the negative sequence voltage after initial limiting to be more accurate.

[0075] Optionally, the positive sequence voltage after initial limiting includes the Q axis positive sequence voltage after initial limiting and the D axis positive sequence voltage after initial limiting, and the negative sequence voltage after initial limiting includes the Q axis negative sequence voltage after initial limiting and the D axis negative sequence voltage after initial limiting.

[0076] like Figure 4 As shown above Figure 3 The process step S31 shown in the figure, according to the maximum limit value, the positive sequence voltage after the initial limit and the negative sequence voltage after the initial limit, performs composite vector limit on the positive sequence voltage after the initial limit to obtain the positive sequence voltage after the composite vector limit, includes:

[0077] S311, using the Q-axis positive sequence voltage after initial limiting, the D-axis positive sequence voltage after initial limiting, the Q-axis negative sequence voltage after initial limiting, and the D-axis negative sequence voltage after initial limiting, the limiting proportional coefficient is calculated, and the limiting proportional coefficient satisfies:

[0078]

[0079] Where V mag represents the limiting ratio coefficient, Indicates the positive sequence voltage of the D axis after the initial limiting. is the Q-axis positive sequence voltage after the initial limiting, is the negative sequence voltage of the D axis after the initial limiting, It is the Q-axis negative sequence voltage after the initial limiting.

[0080] S312, using the maximum limit value, the limit ratio coefficient and the D-axis positive sequence voltage after the initial limit, the D-axis positive sequence voltage after the composite vector limit is calculated, and the D-axis positive sequence voltage after the composite vector limit and the D-axis positive sequence voltage after the initial limit satisfy:

[0081]

[0082] In the formula, Represents the positive sequence voltage of the D axis after the composite vector is limited, V max Indicates the maximum limit value.

[0083] During the operation of the power system, the voltage may fluctuate greatly, and there may be a short-term situation where the positive sequence voltage and negative sequence voltage are superimposed by 2 times. In order to meet specific operation requirements or safety standards, the maximum limit value may be between 1.2 and 1.7. For example, 1.2, 1.5 or 1.7.

[0084] S313, using the maximum limit value, the limit ratio coefficient and the Q-axis positive sequence voltage after the initial limit, the Q-axis positive sequence voltage after the composite vector limit is calculated, and the Q-axis positive sequence voltage after the composite vector limit and the Q-axis positive sequence voltage after the initial limit satisfy:

[0085]

[0086] In the formula, Represents the Q-axis positive sequence voltage after composite vector limiting.

[0087] In this embodiment, after the initial amplitude limiting of the Q-axis positive sequence voltage and the D-axis positive sequence voltage is completed, the Q-axis positive sequence voltage after the initial amplitude limiting and the D-axis positive sequence voltage after the initial amplitude limiting can then be proportionally limited. Specifically, the amplitude limiting proportional coefficient can be calculated according to the above calculation formula. Since the amplitude limiting proportional coefficient is calculated based on the Q-axis positive sequence voltage after the initial amplitude limiting, the D-axis positive sequence voltage after the initial amplitude limiting, the Q-axis negative sequence voltage after the initial amplitude limiting, and the D-axis negative sequence voltage after the initial amplitude limiting, it reflects the comprehensive amplitude of the voltage. Then, the amplitude limiting proportional coefficient and the maximum amplitude limiting value are used to limit the Q-axis positive sequence voltage after the initial amplitude limiting and the D-axis positive sequence voltage after the initial amplitude limiting, respectively, so as to obtain the Q-axis positive sequence voltage after the composite vector amplitude limiting and the D-axis positive sequence voltage after the composite vector amplitude limiting. In the entire amplitude limiting process, after the initial amplitude limiting, the power system can still make further proportional adjustments according to the maximum amplitude limiting value. This amplitude limiting method helps to improve the flexibility and adaptability of the power system, while ensuring that the voltage always remains within a safe range.

[0088] Alternatively, if Figure 5 As shown above Figure 3 The process step S32 shown in the figure performs composite vector limiting on the negative sequence voltage after the initial limiting according to the maximum limiting value, the positive sequence voltage after the initial limiting and the negative sequence voltage after the initial limiting to obtain the negative sequence voltage after the composite vector limiting, including:

[0089] S321, using the maximum limit value, the limit ratio coefficient and the Q-axis negative sequence voltage after the initial limit, calculate the Q-axis negative sequence voltage after the composite vector limit, and the Q-axis negative sequence voltage after the composite vector limit and the Q-axis negative sequence voltage after the initial limit satisfy:

[0090]

[0091] In the formula, Represents the D-axis negative sequence voltage after composite vector limiting.

[0092] S322, using the maximum limit value, the limit ratio coefficient and the D-axis negative sequence voltage after the initial limit, the D-axis negative sequence voltage after the composite vector limit is calculated, and the D-axis negative sequence voltage after the composite vector limit and the D-axis negative sequence voltage after the initial limit satisfy:

[0093]

[0094] In the formula, Represents the Q-axis negative sequence voltage after composite vector limiting.

[0095] In this embodiment, after the initial amplitude limiting of the Q-axis negative sequence voltage and the D-axis negative sequence voltage is completed, the Q-axis negative sequence voltage after the initial amplitude limiting and the D-axis negative sequence voltage after the initial amplitude limiting can then be proportionally limited. Specifically, the amplitude limiting proportional coefficient can be calculated according to the above calculation formula. Since the amplitude limiting proportional coefficient is calculated based on the Q-axis positive sequence voltage after the initial amplitude limiting, the D-axis positive sequence voltage after the initial amplitude limiting, the Q-axis negative sequence voltage after the initial amplitude limiting, and the D-axis negative sequence voltage after the initial amplitude limiting, it reflects the comprehensive amplitude of the voltage. Then, the amplitude limiting proportional coefficient and the maximum amplitude limiting value are used to limit the Q-axis negative sequence voltage after the initial amplitude limiting and the D-axis negative sequence voltage after the initial amplitude limiting, respectively, so as to obtain the Q-axis negative sequence voltage after the composite vector amplitude limiting and the D-axis negative sequence voltage after the composite vector amplitude limiting. In the entire amplitude limiting process, after the initial amplitude limiting, the power system can still make further proportional adjustments according to the maximum amplitude limiting value. This amplitude limiting method helps to improve the flexibility and adaptability of the power system, while ensuring that the voltage always remains within a safe range.

[0096] Alternatively, if Figure 6 As shown, Figure 1 The process step S10 shown is to obtain the voltage of the power electronic equipment, including:

[0097] S11, performing inner loop positive sequence current control on the positive sequence input quantity to obtain the Q axis positive sequence voltage and the D axis positive sequence voltage.

[0098] Among them, the positive sequence input is the initial Q-axis positive sequence current, the initial D-axis positive sequence current, the measured value of the Q-axis positive sequence current, the measured value of the D-axis positive sequence current, the grid-side positive sequence voltage and the grid-side negative sequence voltage. Moreover, the grid-side positive sequence voltage and the grid-side negative sequence voltage are both measured values. Therefore, in this embodiment, by taking the initial Q-axis positive sequence current, the initial D-axis positive sequence current, the measured value of the Q-axis positive sequence current, the measured value of the D-axis positive sequence current, the grid-side positive sequence voltage and the grid-side negative sequence voltage as the positive sequence input, the output of the inner loop positive sequence current control is the Q-axis positive sequence voltage and the D-axis positive sequence voltage, and the Q-axis positive sequence voltage and the D-axis positive sequence voltage can be used to further control the current, thereby ensuring the stable operation of the power system. Moreover, the inner loop positive sequence current control method has the characteristics of high accuracy and high flexibility, which helps to improve the overall performance of the entire power system.

[0099] S12, performing inner loop negative sequence current control on the negative sequence input quantity to obtain the Q axis negative sequence voltage and the D axis negative sequence voltage.

[0100] Among them, the negative-sequence input quantity includes the Q-axis negative-sequence current, the D-axis negative-sequence current, the Q-axis negative-sequence current measured value, the D-axis negative-sequence current measured value, the grid-side positive-sequence voltage and the grid-side negative-sequence voltage.

[0101] In this embodiment, by taking the initial Q-axis negative-sequence current, the initial D-axis negative-sequence current, the Q-axis negative-sequence current measured value, the D-axis negative-sequence current measured value, the grid-side positive-sequence voltage and the grid-side negative-sequence voltage as negative-sequence input quantities, the output quantities of the inner-loop negative-sequence current control are the Q-axis negative-sequence voltage and the D-axis negative-sequence voltage, and the Q-axis negative-sequence voltage and the D-axis negative-sequence voltage can be used to further control the current, thereby ensuring the stable operation of the power system. Moreover, the inner-loop negative-sequence current control method has the characteristics of high accuracy and high flexibility, which helps to improve the overall performance of the entire power system.

[0102] Alternatively, if Figure 7 As shown, in Figure 1 In step S30 of the process shown, based on a preset maximum limit value, composite vector limit is performed on the voltage after the initial limit, and after the composite vector limit voltage is obtained, the control method further includes:

[0103] S40, converting the voltage after the composite vector is limited into a coordinate system to obtain a voltage command value.

[0104] For example, the dq coordinate system can be converted to the abc coordinate system, and the obtained voltage command value can be used as a modulation reference value for the subsequent modulation voltage wave.

[0105] Optionally, the voltage command value includes a positive sequence command value and a negative sequence command value. Figure 8 As shown above Figure 7 The process step S40 shown in the figure, converting the voltage after the composite vector is limited into a coordinate system to obtain a voltage command value, includes:

[0106] S41, coordinate conversion is performed on the D-axis positive sequence voltage after the composite vector is limited and the Q-axis positive sequence voltage after the composite vector is limited to obtain a positive sequence command value.

[0107] S42, coordinate conversion is performed on the D-axis negative-sequence voltage after the composite vector is limited and the Q-axis negative-sequence voltage after the composite vector is limited to obtain a negative-sequence command value.

[0108] In this embodiment, after completing the two limiting of the positive sequence voltage, the D-axis positive sequence voltage after the composite vector limiting and the Q-axis positive sequence voltage after the composite vector limiting are converted from the dq coordinate system to the abc coordinate system, and the D-axis negative sequence voltage after the composite vector limiting and the Q-axis negative sequence voltage after the composite vector limiting are converted from the dq coordinate system to the abc coordinate system. It can be understood that the dq coordinate system is usually used to represent the rotating voltage or current, while the abc coordinate system represents the fixed coordinates in the three-phase system. In this way, the voltage or current in the rotating dq coordinate system can be converted into the actual voltage or current value in the fixed coordinate system. The positive sequence command value and the negative sequence command value after conversion to the abc coordinate system are more suitable for directly controlling the three-phase power supply or load in the power system, thereby ensuring the stable and effective operation of the power system to improve the reliability and other performance of the power system.

[0109] Therefore, this embodiment can be applied to power systems with different structures, and the power system can achieve closed-loop, reliable and efficient execution through data collection, analysis and control.

[0110] Embodiment 2:

[0111] Based on the same inventive concept, this embodiment also provides a low voltage ride through control device for power electronic equipment, such as Fig. 9 As shown, the control device includes:

[0112] The acquisition module 91 is used to acquire the voltage of the power electronic equipment. The voltage of the power electronic equipment includes a positive sequence voltage and a negative sequence voltage.

[0113] The first limiting module 92 is used to limit the voltage based on a preset limiting range to obtain the voltage after the initial limiting.

[0114] The second limiting module 93 is used to limit the voltage after the initial limiting based on a preset maximum limiting value to obtain the voltage after the composite vector limiting.

[0115] Optionally, the limiting range includes a positive sequence voltage limiting range and a negative sequence voltage limiting range.

[0116] Fig. 9 The first limiting module 92 shown includes:

[0117] A first limiting submodule is used to limit the positive sequence voltage to within the positive sequence voltage limiting range according to the positive sequence voltage limiting range, and obtain the positive sequence voltage after the initial limiting;

[0118] The second limiting submodule is used to limit the negative sequence voltage to within the negative sequence voltage limiting range according to the negative sequence voltage limiting range, and obtain the negative sequence voltage after the initial limiting.

[0119] Optionally, the minimum value of the positive-sequence voltage limit range is a first positive-sequence limit value, and the maximum value of the positive-sequence voltage limit range is a second positive-sequence limit value;

[0120] The first clipping submodule specifically includes:

[0121] A first determining unit is used to determine the first positive sequence amplitude limiting value as the positive sequence voltage after initial amplitude limiting when the positive sequence voltage is less than the first positive sequence amplitude limiting value;

[0122] a second determining unit, configured to determine the positive sequence voltage as the positive sequence voltage after primary amplitude limiting when the positive sequence voltage is greater than or equal to the first positive sequence amplitude limiting value and less than or equal to the second positive sequence amplitude limiting value;

[0123] The third determining unit is used to determine the second positive sequence amplitude limiting value as the positive sequence voltage after initial amplitude limiting when the positive sequence voltage is greater than the second positive sequence amplitude limiting value.

[0124] Optionally, the minimum value of the negative-sequence voltage limiting range is the first negative-sequence limiting value, and the maximum value of the negative-sequence voltage limiting range is the second negative-sequence limiting value;

[0125] The first clipping submodule specifically includes:

[0126] a fourth determining unit, configured to determine the first negative sequence amplitude limiting value as the negative sequence voltage after initial amplitude limiting when the negative sequence voltage is less than the first negative sequence amplitude limiting value;

[0127] a fifth determining unit, configured to determine the negative sequence voltage as the negative sequence voltage after primary limiting when the negative sequence voltage is greater than or equal to the first negative sequence limiting value and less than or equal to the second negative sequence limiting value;

[0128] The sixth determining unit is configured to determine the second negative sequence amplitude limiting value as the negative sequence voltage after initial amplitude limiting when the negative sequence voltage is greater than the second negative sequence amplitude limiting value.

[0129] Optionally, Fig. 9 The second limiting module 93 shown includes:

[0130] The third limiting submodule is used to perform composite vector limiting on the positive sequence voltage after the initial limiting according to the maximum limiting value, the positive sequence voltage after the initial limiting, and the negative sequence voltage after the initial limiting, so as to obtain the positive sequence voltage after the composite vector limiting;

[0131] The fourth limiting submodule is used to perform composite vector limiting on the negative sequence voltage after initial limiting according to the maximum limiting value, the positive sequence voltage after initial limiting and the negative sequence voltage after initial limiting to obtain the negative sequence voltage after composite vector limiting.

[0132] Optionally, the positive sequence voltage after the initial limiting includes the Q axis positive sequence voltage after the initial limiting and the D axis positive sequence voltage after the initial limiting, and the negative sequence voltage after the initial limiting includes the Q axis negative sequence voltage after the initial limiting and the D axis negative sequence voltage after the initial limiting;

[0133] The third clipping submodule specifically includes:

[0134] The first calculation unit is used to calculate the limiting proportional coefficient by using the Q-axis positive sequence voltage after the initial limiting, the D-axis positive sequence voltage after the initial limiting, the Q-axis negative sequence voltage after the initial limiting, and the D-axis negative sequence voltage after the initial limiting, and the limiting proportional coefficient satisfies:

[0135]

[0136] Where V mag represents the limiting ratio coefficient, Indicates the positive sequence voltage of the D axis after the initial limiting. is the Q-axis positive sequence voltage after the initial limiting, is the negative sequence voltage of the D axis after the initial limiting, is the Q-axis negative sequence voltage after the initial limiting;

[0137] The second calculation unit is used to calculate the D-axis positive sequence voltage after the composite vector is limited by using the maximum limit value, the limit ratio coefficient and the D-axis positive sequence voltage after the initial limit, and the D-axis positive sequence voltage after the composite vector is limited and the D-axis positive sequence voltage after the initial limit satisfies:

[0138]

[0139] In the formula, Represents the positive sequence voltage of the D axis after the composite vector is limited, V max Indicates the maximum limit value;

[0140] The third calculation unit is used to calculate the Q-axis positive sequence voltage after the composite vector is limited by using the maximum limit value, the limit ratio coefficient and the Q-axis positive sequence voltage after the initial limit, and the Q-axis positive sequence voltage after the composite vector is limited and the Q-axis positive sequence voltage after the initial limit satisfies:

[0141]

[0142] In the formula, Represents the Q-axis positive sequence voltage after composite vector limiting.

[0143] The fourth clipping submodule specifically includes:

[0144] The fourth calculation unit is used to calculate the Q-axis negative sequence voltage after the composite vector is limited by using the maximum limit value, the limit ratio coefficient and the Q-axis negative sequence voltage after the initial limit, and the Q-axis negative sequence voltage after the composite vector is limited and the Q-axis negative sequence voltage after the initial limit satisfies:

[0145]

[0146] In the formula, It represents the negative sequence voltage of D axis after the composite vector is limited;

[0147] The fifth calculation unit is used to calculate the D-axis negative sequence voltage after the composite vector is limited by using the maximum limit value, the limit ratio coefficient and the D-axis negative sequence voltage after the initial limit, and the D-axis negative sequence voltage after the composite vector is limited and the D-axis negative sequence voltage after the initial limit satisfies:

[0148]

[0149] In the formula, Represents the Q-axis negative sequence voltage after composite vector limiting.

[0150] Fig. 9 The acquisition module 91 shown specifically includes:

[0151] The first control submodule is used to perform inner loop positive sequence current control on the positive sequence input quantity to obtain the Q axis positive sequence voltage and the D axis positive sequence voltage, wherein the positive sequence input quantity is the initial Q axis positive sequence current, the initial D axis positive sequence current, the measured value of the Q axis positive sequence current, the measured value of the D axis positive sequence current, the grid side positive sequence voltage and the grid side negative sequence voltage;

[0152] The second control submodule is used to perform inner loop negative sequence current control on the negative sequence input quantity to obtain the Q axis negative sequence voltage and the D axis negative sequence voltage. The negative sequence input quantity includes the Q axis negative sequence current, the D axis negative sequence current, the Q axis negative sequence current measured value, the D axis negative sequence current measured value, the grid side positive sequence voltage and the grid side negative sequence voltage.

[0153] Optionally, the low voltage ride through control device for power electronic equipment further includes:

[0154] The conversion module is used to convert the voltage after the composite vector is limited into a coordinate system to obtain a voltage command value.

[0155] Optionally, the voltage command value includes a positive sequence command value and a negative sequence command value.

[0156] The above conversion module specifically includes:

[0157] The first conversion submodule is used to perform coordinate conversion on the D-axis positive sequence voltage after the composite vector is limited and the Q-axis positive sequence voltage after the composite vector is limited to obtain a positive sequence command value;

[0158] The second conversion submodule is used to perform coordinate conversion on the negative-sequence voltage of the D axis after the composite vector is limited and the negative-sequence voltage of the Q axis after the composite vector is limited to obtain a negative-sequence command value.

[0159] Embodiment 3:

[0160] Based on the same inventive concept, Fig.10 As shown, the present invention also provides a computer device, which includes a processor 901 and a storage medium 902, and the processor 901 and the storage medium 902 are connected via a bus 903. The storage medium 901 is used to store an executable computer program, and the computer program includes program instructions, and the processor is used to execute 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 (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 the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of a low voltage ride-through control method for power electronic equipment in the above embodiment.

[0161] The bus 903 connects the above-mentioned multiple components, and at the same time connects the above-mentioned components to the display controller 904 and the display device and the input / output (I / O) device 905. The input / output (I / O) device 905 can be a mouse, a keyboard, a modem, a network interface, a touch input device, a somatosensory input device, a printer, and other devices. In addition, the input / output device 905 is connected to the power system through the input / output (I / O) controller 906.

[0162] Embodiment 4:

[0163] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in a computer device and, of course, extended storage media supported by the computer device. The computer-readable 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 computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of a low voltage ride-through control method for power electronic equipment in the above embodiment.

[0164] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may 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 code.

[0165] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of 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 produce 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.

[0166] 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.

[0167] 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 in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0168] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A low voltage ride-through control method for power electronic equipment, characterized in that: include: The control method comprises: Acquiring a voltage of the power electronic equipment, where the voltage of the power electronic equipment includes a positive sequence voltage and a negative sequence voltage; Based on a preset limiting range, the voltage is limited to obtain a voltage after initial limiting; Based on a preset maximum amplitude limiting value, composite vector amplitude limiting is performed on the voltage after the initial amplitude limiting to obtain the voltage after composite vector amplitude limiting.

2. The control method according to claim 1, characterized in that: The limiting range includes a positive sequence voltage limiting range and a negative sequence voltage limiting range; The step of limiting the voltage based on a preset limiting range to obtain the voltage after initial limiting includes: According to the positive sequence voltage limiting range, limiting the positive sequence voltage to within the positive sequence voltage limiting range, and obtaining the positive sequence voltage after the initial limiting; According to the negative-sequence voltage limiting range, the negative-sequence voltage is limited to within the negative-sequence voltage limiting range, and the negative-sequence voltage after initial limiting is obtained.

3. The control method according to claim 2, characterized in that: The minimum value of the positive sequence voltage limiting range is the first positive sequence limiting value, and the maximum value of the positive sequence voltage limiting range is the second positive sequence limiting value; The step of limiting the positive sequence voltage to within the positive sequence voltage limiting range according to the positive sequence voltage limiting range and obtaining the positive sequence voltage after initial limiting comprises: When the positive-sequence voltage is less than the first positive-sequence amplitude limiting value, determining the first positive-sequence amplitude limiting value as the positive-sequence voltage after the initial amplitude limiting; When the positive-sequence voltage is greater than or equal to the first positive-sequence amplitude limiting value and less than or equal to the second positive-sequence amplitude limiting value, determining the positive-sequence voltage as the positive-sequence voltage after the initial amplitude limiting; When the positive-sequence voltage is greater than the second positive-sequence amplitude limiting value, the second positive-sequence amplitude limiting value is determined as the positive-sequence voltage after the initial amplitude limiting.

4. The control method according to claim 2 or 3, characterized in that: The minimum value of the negative sequence voltage limiting range is the first negative sequence limiting value, and the maximum value of the negative sequence voltage limiting range is the second negative sequence limiting value; The step of limiting the negative sequence voltage to within the negative sequence voltage limiting range according to the negative sequence voltage limiting range and obtaining the negative sequence voltage after initial limiting includes: When the negative sequence voltage is less than the first negative sequence amplitude limiting value, determining the first negative sequence amplitude limiting value as the negative sequence voltage after the initial amplitude limiting; When the negative sequence voltage is greater than or equal to the first negative sequence amplitude limiting value and less than or equal to the second negative sequence amplitude limiting value, the negative sequence voltage is determined as the negative sequence voltage after the initial amplitude limiting; When the negative-sequence voltage is greater than the second negative-sequence amplitude limiting value, the second negative-sequence amplitude limiting value is determined as the negative-sequence voltage after the initial amplitude limiting.

5. The control method according to claim 4, characterized in that: The step of performing composite vector limiting on the voltage after the initial limiting based on the preset maximum limiting value to obtain the voltage after composite vector limiting includes: According to the maximum amplitude limiting value, the positive sequence voltage after the initial amplitude limiting and the negative sequence voltage after the initial amplitude limiting, composite vector amplitude limiting is performed on the positive sequence voltage after the initial amplitude limiting to obtain the positive sequence voltage after the composite vector amplitude limiting; According to the maximum amplitude limiting value, the positive sequence voltage after the initial amplitude limiting and the negative sequence voltage after the initial amplitude limiting, composite vector amplitude limiting is performed on the negative sequence voltage after the initial amplitude limiting to obtain the negative sequence voltage after composite vector amplitude limiting.

6. The control method according to claim 5, characterized in that: The positive sequence voltage after the initial amplitude limiting includes the Q axis positive sequence voltage after the initial amplitude limiting and the D axis positive sequence voltage after the initial amplitude limiting, and the negative sequence voltage after the initial amplitude limiting includes the Q axis negative sequence voltage after the initial amplitude limiting and the D axis negative sequence voltage after the initial amplitude limiting; The step of performing composite vector limiting on the positive sequence voltage after the initial limiting according to the maximum limiting value, the positive sequence voltage after the initial limiting, and the negative sequence voltage after the initial limiting to obtain the positive sequence voltage after composite vector limiting includes: The limiting proportional coefficient is calculated using the Q-axis positive sequence voltage after the initial limiting, the D-axis positive sequence voltage after the initial limiting, the Q-axis negative sequence voltage after the initial limiting, and the D-axis negative sequence voltage after the initial limiting. The limiting proportional coefficient satisfies: Where V mag represents the clipping ratio coefficient, Indicates the positive sequence voltage of the D axis after the initial limiting. is the Q-axis positive sequence voltage after the initial limiting, is the negative sequence voltage of the D axis after the initial limiting, is the Q-axis negative sequence voltage after initial limiting; The D-axis positive sequence voltage after composite vector limiting is calculated by using the maximum limiting value, the limiting proportional coefficient and the D-axis positive sequence voltage after the initial limiting, and the D-axis positive sequence voltage after composite vector limiting satisfies the following relationship with the D-axis positive sequence voltage after the initial limiting: In the formula, represents the D-axis positive sequence voltage after the composite vector is limited, V max represents the maximum limit value; The Q-axis positive-sequence voltage after composite vector limiting is calculated by using the maximum limiting value, the limiting proportional coefficient and the Q-axis positive-sequence voltage after the initial limiting, and the Q-axis positive-sequence voltage after composite vector limiting satisfies the following relationship with the Q-axis positive-sequence voltage after the initial limiting: In the formula, Represents the Q-axis positive sequence voltage after composite vector limiting.

7. The control method according to claim 6, characterized in that: The step of performing composite vector limiting on the negative sequence voltage after the initial limiting according to the maximum limiting value, the positive sequence voltage after the initial limiting, and the negative sequence voltage after the initial limiting to obtain the negative sequence voltage after composite vector limiting includes: The Q-axis negative-sequence voltage after composite vector limiting is calculated by using the maximum limiting value, the limiting proportional coefficient and the Q-axis negative-sequence voltage after the initial limiting, and the Q-axis negative-sequence voltage after composite vector limiting satisfies the following relationship with the Q-axis negative-sequence voltage after the initial limiting: In the formula, It represents the negative sequence voltage of D axis after the composite vector is limited; The D-axis negative-sequence voltage after composite vector limiting is calculated by using the maximum limiting value, the limiting proportional coefficient and the D-axis negative-sequence voltage after the initial limiting, and the D-axis negative-sequence voltage after composite vector limiting satisfies the following relationship with the D-axis negative-sequence voltage after the initial limiting: In the formula, Represents the Q-axis negative sequence voltage after composite vector limiting.

8. The control method according to claim 1, characterized in that: The step of obtaining the voltage of the power electronic equipment comprises: Performing inner loop positive-sequence current control on the positive-sequence input quantity to obtain a Q-axis positive-sequence voltage and a D-axis positive-sequence voltage, wherein the positive-sequence input quantity is an initial Q-axis positive-sequence current, an initial D-axis positive-sequence current, a measured value of the Q-axis positive-sequence current, a measured value of the D-axis positive-sequence current, a grid-side positive-sequence voltage, and a grid-side negative-sequence voltage; An inner loop negative-sequence current control is performed on the negative-sequence input quantity to obtain a Q-axis negative-sequence voltage and a D-axis negative-sequence voltage. The negative-sequence input quantity includes a Q-axis negative-sequence current, a D-axis negative-sequence current, a Q-axis negative-sequence current measured value, a D-axis negative-sequence current measured value, the grid-side positive-sequence voltage, and the grid-side negative-sequence voltage.

9. The control method according to claim 8, characterized in that: After the step of performing composite vector limiting on the voltage after the initial limiting based on the preset maximum limiting value to obtain the voltage after composite vector limiting, the control method further includes: The voltage after the composite vector is limited is subjected to coordinate system transformation to obtain a voltage command value.

10. A low voltage ride through control device for power electronic equipment, characterized in that: The control device comprises: An acquisition module, used for acquiring the voltage of the power electronic equipment, where the voltage of the power electronic equipment includes a positive sequence voltage and a negative sequence voltage; A first limiting module, used for limiting the voltage based on a preset limiting range to obtain a voltage after initial limiting; The second limiting module is used to limit the voltage after the initial limiting based on a preset maximum limiting value to obtain the voltage after the composite vector limiting.

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