Overvoltage protection method and device, electronic equipment and medium

Abstract

The invention discloses an overvoltage protection method and device, electronic equipment and a medium, and relates to the field of new energy, and the method comprises the steps: determining a PWM (Pulse Width Modulation) wave sealing value of any IGBT (Insulated Gate Bipolar Translator) in a rotor side converter and a power grid side converter in a wind turbine generator, and determining a first overvoltage fault protection value of a DC bus capacitor corresponding to the converter according to the PWM wave sealing value; the first overvoltage fault protection value must be larger than the PWM wave sealing value, when the current voltage value of the direct current bus capacitor is larger than the PWM wave sealing value, all IGBTs need to be controlled to be turned off, whether the current voltage value is larger than the first overvoltage fault protection value or not is judged, and if the current voltage value is larger than the first overvoltage fault protection value, it is judged that the direct current bus capacitor has an overvoltage fault; and controlling the wind turbine generator to break away from the power grid. According to the scheme, the wind turbine generator is controlled to be separated from the power grid only when the DC bus voltage is greater than the first overvoltage fault protection value, the probability that the wind turbine generator is separated from the power grid is greatly reduced, and the stability of the power grid is improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy, and in particular to an overvoltage protection method, device, electronic equipment and medium. Background Art

[0002] At present, the competition in the new energy industry is fierce. Many manufacturers have reduced costs in device selection. Device performance is more likely to reach critical values ​​under extreme working conditions, especially for converters. Doubly fed asynchronous wind turbine generator (DFIG, DoublyFed Induction Generator), rotor side converter, DC bus capacitor, grid side converter, and grid are connected in sequence. The structure is as follows Figure 1 As shown, the protection voltage value of the rotor-side converter is equal to the protection voltage value of the grid-side converter. If the protection voltage value of the rotor-side converter and the grid-side converter is exceeded, the wind turbine will actively shut down and disconnect from the grid. For example, when the grid voltage suddenly drops, due to the inertia of the generator rotor of the wind turbine, the excess active power cannot be transmitted, and will flow into the DC bus capacitor, the rotor-side converter and the grid-side converter, causing the DC bus and the converter voltage in the wind turbine to increase.

[0003] Since both the rotor-side converter and the grid-side converter contain multiple IGBTs (Insulate-Gate Bipolar Transistor, insulated gate bipolar transistor), and the protection voltage value of each IGBT is the same, and the voltage of the IGBT cannot be directly measured, so the overvoltage protection of the IGBT is protected by the voltage of the DC bus capacitor, that is, when it is detected that the DC bus capacitor voltage exceeds the preset value, all IGBTs in the rotor-side converter and the grid-side converter are controlled to be turned off, but because of the IGBT characteristic-there is a turn-off voltage spike, so the maximum withstand voltage of the IGBT in the operating state is lower than the maximum withstand voltage of the IGBT in the closed state. For example, the protection voltage of the IGBT with a rated voltage of 1700V should be set to less than 1200V when it is in action, but it can withstand a higher voltage in the closed state. The allowable withstand voltage of the DC bus capacitor is generally higher than the protection voltage of the IGBT in the operating state, but in order to protect the IGBT in the prior art, the DC bus capacitor overvoltage threshold is generally set to the protection voltage value of the IGBT. This method cannot give full play to the voltage resistance of the DC bus capacitor. Under extreme grid conditions, it is easier to trigger the overvoltage threshold, resulting in an increased probability of wind turbine failure and disconnection from the grid, which further impacts the grid. Summary of the invention

[0004] The purpose of the present invention is to provide an overvoltage protection method, device, electronic device and medium. This scheme will control the wind turbine to be disconnected from the power grid only when the DC bus voltage is greater than the first overvoltage fault protection value, which greatly reduces the probability of the wind turbine being disconnected from the power grid and improves the stability of the power grid.

[0005] In order to solve the above technical problems, the present invention provides an overvoltage protection method, comprising:

[0006] Obtaining a rated protection voltage value when any IGBT in the converter of the wind turbine generator set is in operation, and using the rated protection voltage value as a PWM wave envelope value of each IGBT, wherein the converter comprises: a rotor-side converter and a grid-side converter, and the rated protection voltage values ​​of each IGBT in operation are equal;

[0007] Setting a first overvoltage fault protection value of a DC bus capacitor corresponding to the converter according to the PWM wave-enclosing value, wherein the first overvoltage fault protection value is greater than the PWM wave-enclosing value, and the first overvoltage fault protection value meets the voltage protection requirements of the DC bus capacitor and each of the IGBTs in the off state;

[0008] Collecting the current voltage value of the DC bus capacitor, and determining whether the current voltage value is greater than the PWM wave-sealing value;

[0009] If the current voltage value is greater than the PWM envelope value, a shutdown signal is sent to each IGBT in the rotor-side converter and the grid-side converter to control each IGBT to shut down, and determine whether the current voltage value is greater than the first overvoltage fault protection value;

[0010] If the current voltage value is greater than the first overvoltage fault protection value, it is determined that an overvoltage fault occurs in the DC bus capacitor, and the wind turbine is controlled to be disconnected from the power grid.

[0011] Optionally, controlling each of the IGBTs to turn off includes:

[0012] Continuously sending the shutdown signal to each of the IGBTs within a first preset time period to control each of the IGBTs to shut down;

[0013] After controlling each of the IGBTs to turn off, the method further includes:

[0014] collecting the voltage of the DC bus capacitor after the first preset time period;

[0015] Determining whether the voltage of the DC bus capacitor after the first preset time period is less than the PWM wave-sealing value;

[0016] If the voltage of the DC bus capacitor after the first preset time period is less than the PWM envelope value, a start signal is sent to each of the IGBTs to control each of the IGBTs to turn on.

[0017] Optionally, after controlling each of the IGBTs to turn off, the method further includes:

[0018] Determining an actual turn-off time of each of the IGBTs;

[0019] Determine whether the actual shutdown time is greater than a preset shutdown time threshold;

[0020] If the actual shutdown time is greater than the preset shutdown time threshold, it is determined that a long blocking time fault occurs in each of the IGBTs, and the wind turbine is controlled to shut down.

[0021] Optionally, determining the actual turn-off time of each IGBT includes:

[0022] Determine the first moment when the current voltage value is equal to the PWM envelope value for the first time;

[0023] Determine a second moment when the current voltage value is equal to the PWM envelope value for the second time;

[0024] The actual turn-off time is determined according to the difference between the second moment and the first moment.

[0025] Optionally, also include:

[0026] Obtaining a current value of the DC bus capacitor;

[0027] Determining whether the current value is greater than a preset current threshold;

[0028] If the current current value is greater than the preset current threshold, the shutdown signal is sent to each IGBT in the rotor-side converter and the grid-side converter to control each IGBT to be shut down.

[0029] Optionally, before determining whether the current voltage value is greater than the first overvoltage fault protection value, the method further includes:

[0030] The second overvoltage fault protection value of the DC bus capacitor is set according to the first overvoltage fault protection value and the PWM wave-enclosing value, wherein the second overvoltage fault protection value is greater than the PWM wave-enclosing value, and the second overvoltage fault protection value is less than the first overvoltage fault protection value;

[0031] Determining whether the current voltage value is greater than the second overvoltage fault protection value;

[0032] If the current voltage value is greater than the second overvoltage fault protection value, a step of determining whether the current voltage value is greater than the first overvoltage fault protection value is triggered.

[0033] Optionally, after the current voltage value is greater than the second overvoltage fault protection value, the method further includes:

[0034] Determining whether the voltage of the power grid is less than a preset voltage threshold within a second preset time period;

[0035] If the voltage of the power grid is less than a preset voltage threshold value within a second preset time period, until the voltage of the power grid is not less than the preset voltage threshold value, triggering the step of collecting the current voltage value of the DC bus capacitor and determining whether the current voltage value is greater than the PWM wave value;

[0036] If the voltage of the power grid is not less than the preset voltage threshold within the second preset time period, the step of determining whether the current voltage value is greater than the first overvoltage fault protection value is triggered.

[0037] In order to solve the above technical problems, the present invention also provides an overvoltage protection device, comprising:

[0038] An acquisition unit is used to acquire a rated protection voltage value when any IGBT in a converter in a wind turbine generator set is in operation, and use the rated protection voltage value as a PWM wave envelope value of each IGBT, wherein the converter includes: a rotor-side converter and a grid-side converter, and the rated protection voltage values ​​of each IGBT in operation are equal;

[0039] A setting unit, configured to set a first overvoltage fault protection value of a DC bus capacitor corresponding to the converter according to the PWM wave-enclosing value, wherein the first overvoltage fault protection value is greater than the PWM wave-enclosing value, and the first overvoltage fault protection value satisfies a voltage protection requirement of the DC bus capacitor and each of the IGBTs in a shutdown state;

[0040] A collection unit, used for collecting the current voltage value of the DC bus capacitor and determining whether the current voltage value is greater than the PWM wave-sealing value;

[0041] a first determination unit, configured to send a shutdown signal to each IGBT in the rotor-side converter and the grid-side converter to control each IGBT to shut down when the current voltage value is greater than the PWM envelope value, and to determine whether the current voltage value is greater than the first overvoltage fault protection value;

[0042] The second determination unit is used to determine that an overvoltage fault occurs in the DC bus capacitor when the current voltage value is greater than the first overvoltage fault protection value, and to control the wind turbine to be disconnected from the power grid.

[0043] In order to solve the above technical problems, the present invention further provides an electronic device, comprising:

[0044] Memory for storing computer programs;

[0045] A processor is used to implement the steps of the overvoltage protection method as described above when executing the computer program.

[0046] In order to solve the above technical problem, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the overvoltage protection method as described above are implemented.

[0047] The purpose of the present invention is to provide an overvoltage protection method, device, electronic device and medium, to determine the PWM wave-blocking value of any IGBT in the rotor-side converter and the grid-side converter in the wind turbine, and to determine the first overvoltage fault protection value of the DC bus capacitor corresponding to the converter according to the PWM wave-blocking value, and the first overvoltage fault protection value must be greater than the PWM wave-blocking value. When the current voltage value of the DC bus capacitor is greater than the PWM wave-blocking value, it is necessary to control all IGBTs to be turned off, and to determine whether the current voltage value is greater than the first overvoltage fault protection value. If the current voltage value is greater than the first overvoltage fault protection value, it is determined that the DC bus capacitor has an overvoltage fault, and the wind turbine is controlled to be disconnected from the grid. This scheme will control the wind turbine to be disconnected from the grid only when the DC bus voltage is greater than the first overvoltage fault protection value, which greatly reduces the probability of the wind turbine being disconnected from the grid and improves the stability of the grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0049] Figure 1 A schematic diagram of the electrical structure of a doubly-fed wind turbine provided by the present invention;

[0050] Figure 2 A process flow chart of an overvoltage protection method provided by the present invention;

[0051] Figure 3 A schematic diagram of a DC bus capacitor overvoltage triggering PWM wave sealing I protection and maintaining normal operation provided by the present invention;

[0052] Figure 4A schematic diagram of a DC bus capacitor overvoltage triggering stage I protection provided by the present invention, but maintaining normal operation after receiving a fault ride-through signal;

[0053] Figure 5 A schematic diagram of a DC bus capacitor overvoltage triggering stage II protection provided by the present invention, in which the machine stops faulting after receiving no fault ride-through signal for 10ms;

[0054] Figure 6 A schematic diagram of a DC bus capacitor overvoltage triggering stage III protection and immediate fault shutdown provided by the present invention;

[0055] Figure 7 A schematic diagram of a converter A phase and a DC side circuit provided by the present invention;

[0056] Figure 8 A schematic structural diagram of an overvoltage protection device provided by the present invention;

[0057] Fig. 9 The present invention provides a schematic structural diagram of an electronic device. DETAILED DESCRIPTION

[0058] The core of the present invention is to provide an overvoltage protection method, device, electronic equipment and medium. This scheme will control the wind turbine to be disconnected from the power grid only when the DC bus voltage is greater than the first overvoltage fault protection value, which greatly reduces the probability of the wind turbine being disconnected from the power grid and improves the stability of the power grid.

[0059] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] Please refer to Figure 2 , Figure 2 A process flow chart of an overvoltage protection method provided by the present invention. The overvoltage protection method comprises:

[0061] S11: obtaining a rated protection voltage value when any IGBT in the converter of the wind turbine generator set is in operation, and using the rated protection voltage value as a PWM wave envelope value of each IGBT, the converter includes: a rotor-side converter and a grid-side converter, and the rated protection voltage value of each IGBT in operation is equal;

[0062] S12: setting a first overvoltage fault protection value of a DC bus capacitor corresponding to the converter according to the PWM wave blocking value, the first overvoltage fault protection value being greater than the PWM wave blocking value, and the first overvoltage fault protection value meeting the voltage protection requirements of the DC bus capacitor and each IGBT in the off state;

[0063] S13: Collect the current voltage value of the DC bus capacitor and determine whether the current voltage value is greater than the PWM wave-sealing value;

[0064] S14: If the current voltage value is greater than the PWM wave-sealing value, a shutdown signal is sent to each IGBT in the rotor-side converter and the grid-side converter to control each IGBT to shut down, and determine whether the current voltage value is greater than the first overvoltage fault protection value;

[0065] S15: If the current voltage value is greater than the first overvoltage fault protection value, it is determined that an overvoltage fault occurs in the DC bus capacitor, and the wind turbine is controlled to be disconnected from the grid.

[0066] In the present invention, considering that in the prior art, in order to protect the IGBT, the DC bus capacitor overvoltage threshold is generally set to the protection voltage value of the IGBT, this method cannot give full play to the voltage resistance capability of the DC bus capacitor, and it is more likely to trigger the overvoltage threshold under extreme grid conditions, resulting in an increased probability of wind turbine failure and disconnection from the grid, further causing impact on the grid. Therefore, in order to reduce the probability of wind turbines being triggered off the grid, this application uses the rated protection voltage value when the IGBT is in action as its own PWM (Pulse Width Modulation) blocking value. When the current voltage value of the DC bus capacitor is greater than the PWM blocking value, the IGBT is controlled to be turned off, and the first overvoltage fault protection value of the DC bus capacitor corresponding to the converter is determined according to the PWM blocking value. The first overvoltage fault protection value must be greater than the PWM blocking value, and the first overvoltage fault protection value needs to meet the voltage protection requirements of the DC bus capacitor and each IGBT in the off state, that is, the triggering of the first overvoltage fault protection value needs to simultaneously protect the IGBT and the DC bus capacitor in the off state. When the current voltage value of the DC bus capacitor is greater than the first overvoltage fault protection value, it is determined that the DC bus capacitor has an overvoltage fault, and the wind turbine is controlled to be disconnected from the grid. Because the voltage value that triggers the wind turbine to be disconnected from the grid is greater than the rated protection voltage value of the IGBT, this solution greatly reduces the probability of the wind turbine being disconnected from the grid and improves the stability of the grid.

[0067] It should be noted that this application innovatively designs an IGBT module PWM overvoltage blocking algorithm, and optimizes the DC bus capacitor overvoltage fault protection, combining the two protection methods of PWM blocking and fault shutdown to form a three-stage overvoltage protection algorithm. It not only effectively protects the IGBT module, but also makes full use of the voltage resistance of the DC bus capacitor, and increases the original DC bus capacitor overvoltage fault threshold from B1 (PWM blocking value) to P2 (second overvoltage fault protection value). When the grid voltage fails, the probability of the wind turbine unit shutting down and disconnecting from the grid can be reduced, and when an overvoltage fault actually occurs, it can also quickly disconnect from the grid to protect the unit safety. Only by optimizing the software, without increasing the cost of hardware transformation, the stability of the grid and the safety of the unit can be improved, which has certain economic benefits.

[0068] It should also be noted that the overvoltage protection process of this application is roughly as follows:

[0069] Step 1: Set the PWM wave value to B1 according to the protection voltage under the IGBT action state, which is stage I protection;

[0070] Step 2: Set the DC bus capacitor stage I overvoltage fault protection value P1 (first overvoltage fault protection value), P1>B1, for stage II protection;

[0071] Step 3: Set the DC bus capacitor stage II overvoltage fault protection value P2 (second overvoltage fault protection value), P2>P1. This protection value needs to protect both the IGBT and the DC bus capacitor in the off state, which is stage III protection.

[0072] Step 4: Figure 3 As shown, if the DC bus voltage exceeds the B1 value, the IGBT is immediately blocked for 10ms (all IGBTs are controlled to be closed for 10ms), and the IGBT is restarted only after the 10ms (first preset time period) timing ends and the voltage value of the DC bus capacitor is lower than the B1 value;

[0073] Step 5: If the blocking time exceeds 30ms (the preset shutdown time threshold), a blocking time too long fault is reported and the machine shuts down.

[0074] Step 6: Figure 4 As shown in the figure, if the voltage value of the DC bus capacitor exceeds the P1 value, the fault is not immediately reported and the network is disconnected. It waits for 10ms (the second preset time period). If a fault ride-through signal is detected during the waiting period, the fault is shielded until the fault ride-through state is exited and normal operation continues. Figure 5 As shown in the figure, if no fault crossing signal is detected within 10ms, the overvoltage fault of the DC bus capacitor section II will be reported immediately after 10ms and the grid will be disconnected;

[0075] Step 7: Figure 6As shown, if the voltage value of the DC bus capacitor exceeds the P2 value, the DC bus capacitor section III overvoltage fault will be reported immediately and the grid will be disconnected;

[0076] Step 8: In order not to affect the IGBT overcurrent protection, the overvoltage protection flag and the overcurrent protection flag should use "OR" logic, and once triggered, they must be immediately blocked (IGBT will be shut down if overvoltage or overcurrent occurs).

[0077] It should also be noted that if Figure 7 As shown in the figure, in order to protect the IGBT and DC bus capacitor from overvoltage, a chopper module is connected in parallel to the DC bus capacitor. When the DC bus capacitor voltage rises to the chopper module trigger threshold, the chopper resistor is turned on to release excess energy and reduce the DC bus voltage. If the chopper fails to release energy in time, causing the DC bus capacitor to overvoltage, the overvoltage protection will be triggered and the unit will be disconnected from the grid.

[0078] This embodiment provides an overvoltage protection method, which determines the PWM wave-blocking value of any IGBT in the rotor-side converter and the grid-side converter in the wind turbine, and determines the first overvoltage fault protection value of the DC bus capacitor corresponding to the converter according to the PWM wave-blocking value, and the first overvoltage fault protection value must be greater than the PWM wave-blocking value. When the current voltage value of the DC bus capacitor is greater than the PWM wave-blocking value, it is necessary to control all IGBTs to turn off, and determine whether the current voltage value is greater than the first overvoltage fault protection value. If the current voltage value is greater than the first overvoltage fault protection value, it is determined that the DC bus capacitor has an overvoltage fault, and the wind turbine is controlled to disconnect from the grid. This solution will control the wind turbine to disconnect from the grid only when the DC bus voltage is greater than the first overvoltage fault protection value, which greatly reduces the probability of the wind turbine disconnecting from the grid and improves the stability of the grid.

[0079] Based on the above embodiments:

[0080] As an optional embodiment, controlling each IGBT to turn off includes:

[0081] Continuously sending a shutdown signal to each IGBT within a first preset time period to control each IGBT to shut down;

[0082] After controlling each IGBT to turn off, it also includes:

[0083] Collecting the voltage of the DC bus capacitor after a first preset time period;

[0084] Determine whether the voltage of the DC bus capacitor after the first preset time period is less than the PWM blocking wave value;

[0085] If the voltage of the DC bus capacitor after the first preset time period is less than the PWM blocking value, a start signal is sent to each IGBT to control each IGBT to turn on.

[0086] In this description, it is considered that after the IGBT is turned off for the first time, it is necessary to ensure that the voltage value of the DC bus capacitor is less than the PWM wave-blocking value when it is turned on again, and the shutdown needs to be maintained for at least a certain time, otherwise the IGBT is prone to failure. Among them, the specific process of controlling the shutdown of each IGBT is to continuously send a shutdown signal to each IGBT within the first preset time period to control the shutdown of each IGBT. Secondly, after controlling the shutdown of each IGBT, this scheme will collect the voltage of the DC bus capacitor after the first preset time period, that is, monitor the voltage of the DC bus capacitor in real time, and determine whether the voltage of the DC bus capacitor after the first preset time period is less than the PWM wave-blocking value. If the voltage of the DC bus capacitor after the first preset time period is less than the PWM wave-blocking value, a start signal can be sent to each IGBT to control the opening of each IGBT; on the contrary, if the voltage of the DC bus capacitor after the first preset time period is not less than the PWM wave-blocking value, it cannot be guaranteed that the voltage of the IGBT drops below the PWM wave-blocking value, and in fact, each IGBT cannot be controlled to be turned on, which improves the reliability and safety of the scheme.

[0087] As an optional embodiment, after controlling each IGBT to turn off, the method further includes:

[0088] Determine the actual turn-off time of each IGBT;

[0089] Determine whether the actual shutdown time is greater than the preset shutdown time threshold;

[0090] If the actual shutdown time is greater than the preset shutdown time threshold, it is determined that each IGBT has a long blocking time fault and the wind turbine is controlled to shut down.

[0091] In the present invention, considering that if the IGBT is shut down because the voltage of the DC bus capacitor is greater than the PWM blocking value, if the shutdown time is too long, it may cause damage to the wind turbine. Therefore, this scheme needs to determine the actual shutdown time of each IGBT and judge whether the actual shutdown time is greater than the preset shutdown time threshold. If the actual shutdown time is greater than the preset shutdown time threshold, each IGBT may have a long blocking time fault. At this time, in order to ensure the safety of the wind turbine, it is necessary to control the wind turbine to shut down, thereby improving the safety of the scheme.

[0092] As an optional embodiment, determining the actual turn-off time of each IGBT includes:

[0093] Determine the first moment when the current voltage value is equal to the PWM envelope value for the first time;

[0094] Determine the second moment when the current voltage value is equal to the PWM envelope value for the second time;

[0095] The actual turn-off time is determined according to the difference between the second moment and the first moment.

[0096] In the present invention, considering that the turn-off time of the IGBT is positively correlated with whether the voltage value of the DC bus capacitor is greater than the PWM blocking value, the specific process of determining the actual turn-off time of each IGBT is: first determine the first moment when the current voltage value is equal to the PWM blocking value for the first time, and then determine the second moment when the current voltage value is equal to the PWM blocking value for the second time. Therefore, the time between the first moment and the second moment is the actual turn-off time of the IGBT. Therefore, the actual turn-off time can be accurately determined according to the difference between the second moment and the first moment, thereby ensuring the accuracy of the actual turn-off time determination process.

[0097] As an optional embodiment, it also includes:

[0098] Get the current value of the DC bus capacitor;

[0099] Determine whether the current value is greater than a preset current threshold;

[0100] If the current value is greater than the preset current threshold, a shutdown signal is sent to each IGBT in the rotor-side converter and the grid-side converter to control each IGBT to shut down.

[0101] In the present invention, it is considered that in actual applications, when an overvoltage fault occurs in the IGBT, it is necessary to control the IGBT to shut down to ensure the safety of the IGBT. In addition, when an overcurrent fault occurs in the IGBT, it is also necessary to control the IGBT to shut down to ensure the safety of the IGBT. The overvoltage shutdown and the overcurrent shutdown are in an "or" relationship, so this scheme also needs to additionally obtain the current current value of the DC bus capacitor and determine whether the current current value is greater than the preset current threshold. If the current current value is greater than the preset current threshold, it is also necessary to send a shutdown signal to each IGBT in the rotor-side converter and the grid-side converter to control the shutdown of each IGBT. This scheme adds an overcurrent protection process on the basis of overvoltage protection, thereby providing double protection for the safety of the wind turbine.

[0102] As an optional embodiment, before determining whether the current voltage value is greater than the first overvoltage fault protection value, the method further includes:

[0103] The second overvoltage fault protection value of the DC bus capacitor is set according to the first overvoltage fault protection value and the PWM wave-sealing value, wherein the second overvoltage fault protection value is greater than the PWM wave-sealing value, and the second overvoltage fault protection value is less than the first overvoltage fault protection value;

[0104] Determine whether the current voltage value is greater than the second overvoltage fault protection value;

[0105] If the current voltage value is greater than the second overvoltage fault protection value, the step of determining whether the current voltage value is greater than the first overvoltage fault protection value is triggered.

[0106] In the present invention, considering that there is only one layer of voltage protection of the DC bus capacitor, errors are prone to occur, and overvoltage faults may be triggered multiple times due to the influence of environmental factors, thereby causing the wind turbine to be disconnected from the grid multiple times, affecting the stability of the power grid. Therefore, this scheme will also determine the second overvoltage fault protection value of the DC bus capacitor based on the first overvoltage fault protection value and the PWM wave sealing value, wherein the second overvoltage fault protection value must be greater than the PWM wave sealing value and must be less than the first overvoltage fault protection value. At this time, it is judged whether the current voltage value is greater than the second overvoltage fault protection value. If the second current voltage value is greater than the second overvoltage fault protection value, the step of judging whether the current voltage value is greater than the first overvoltage fault protection value is triggered, thereby reducing the triggering probability of the wind turbine being disconnected from the grid and simultaneously ensuring the safety of the converter and the DC bus capacitor.

[0107] As an optional embodiment, after the current voltage value is greater than the second overvoltage fault protection value, the method further includes:

[0108] Determine whether the voltage of the power grid is less than a preset voltage threshold within a second preset time period;

[0109] If the voltage of the power grid is less than the preset voltage threshold value within the second preset time period, until the voltage of the power grid is not less than the preset voltage threshold value, trigger the step of collecting the current voltage value of the DC bus capacitor and judging whether the current voltage value is greater than the PWM wave sealing value;

[0110] If the voltage of the power grid is not less than the preset voltage threshold value within the second preset time period, the step of determining whether the current voltage value is greater than the first overvoltage fault protection value is triggered.

[0111] In the present invention, taking into account the existing low voltage ride-through test, the converter will send out a fault ride-through signal when it detects that the grid voltage is reduced. Because when the grid voltage drops, the excess active power charges the DC bus capacitor, which can easily cause bus overvoltage. Therefore, the second overvoltage fault protection value is set. If it exceeds the second overvoltage fault protection value but the fault ride-through signal is detected, it means that there is a grid fault and there is no need to report the fault at this time. However, if the fault ride-through signal is not detected at this time, it means that it is not a grid problem, but a problem with the converter's own control or components that causes the DC bus capacitor to overvoltage. At this time, the fault should be reported to protect the converter. Therefore, after determining that the current voltage value is greater than the second overvoltage fault protection value, this scheme will determine whether the grid voltage is less than the preset voltage threshold in the second preset time period thereafter. If the second If the voltage of the power grid is less than the preset voltage threshold within the preset time period, the step of collecting the current voltage value of the DC bus capacitor and judging whether the current voltage value is greater than the PWM sealing wave value is triggered until the voltage of the power grid is not less than the preset voltage threshold, that is, until the power grid leaves the low voltage state and then operates normally; conversely, if the voltage of the power grid is not less than the preset voltage threshold within the second preset time period, the step of judging whether the current voltage value is greater than the first overvoltage fault protection value is directly triggered, because at this time it is proved that the problem is not the power grid, but the problem of the converter's own control or the device causes the voltage of the DC bus capacitor to exceed the second overvoltage fault protection value. At this time, it is necessary to continue to judge whether the current voltage is greater than the first overvoltage fault protection value to judge whether an overvoltage fault has actually occurred at the current moment, thereby improving the accuracy of the solution.

[0112] Please refer to Figure 8 , Figure 8 The present invention provides a schematic diagram of the structure of an overvoltage protection device. The overvoltage protection device includes:

[0113] The acquisition unit 11 is used to acquire the rated protection voltage value when any IGBT in the converter of the wind turbine is in operation, and use the rated protection voltage value as the PWM wave value of each IGBT, the converter includes: a rotor-side converter and a grid-side converter, and the rated protection voltage value of each IGBT in operation is equal;

[0114] A setting unit 12, used to set a first overvoltage fault protection value of a DC bus capacitor corresponding to the converter according to the PWM wave-blocking value, the first overvoltage fault protection value is greater than the PWM wave-blocking value, and the first overvoltage fault protection value meets the voltage protection requirements of the DC bus capacitor and each IGBT in the off state;

[0115] The acquisition unit 13 is used to acquire the current voltage value of the DC bus capacitor and determine whether the current voltage value is greater than the PWM wave value;

[0116] The first determination unit 14 is used to send a shutdown signal to each IGBT in the rotor-side converter and the grid-side converter to control each IGBT to shut down when the current voltage value is greater than the PWM envelope value, and to determine whether the current voltage value is greater than the first overvoltage fault protection value;

[0117] The second determination unit 15 is used to determine that an overvoltage fault occurs in the DC bus capacitor when the current voltage value is greater than the first overvoltage fault protection value, and control the wind turbine to disconnect from the power grid.

[0118] The overvoltage protection device provided in this embodiment corresponds to the above method, and thus has the same beneficial effects as the above method. Therefore, for the embodiments of the overvoltage protection device part, please refer to the description of the embodiments of the method part, which will not be repeated here.

[0119] Please refer to Fig. 9 , Fig. 9 A schematic diagram of the structure of an electronic device provided by the present invention. The electronic device comprises:

[0120] A memory 20, used for storing computer programs;

[0121] The processor 21 is used to implement the steps of the above-mentioned overvoltage protection method when executing a computer program.

[0122] The electronic device provided in this embodiment may include but is not limited to a smart phone, a tablet computer, a laptop computer or a desktop computer.

[0123] Among them, the processor 21 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 21 can be implemented in at least one hardware form of a digital signal processor (DSP), a field-programmable gate array (FPGA), and a programmable logic array (PLA). The processor 21 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a central processing unit (CPU); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 21 may be integrated with a graphics processing unit (GPU), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 21 may also include an artificial intelligence (AI) processor, which is used to process computing operations related to machine learning.

[0124] The memory 20 may include one or more computer-readable storage media, which may be non-transitory. The memory 20 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In this embodiment, the memory 20 is at least used to store the following computer program 201, wherein, after the computer program is loaded and executed by the processor 21, it can implement the relevant steps of the overvoltage protection method disclosed in any of the aforementioned embodiments. In addition, the resources stored in the memory 20 may also include an operating system 202 and data 203, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system 202 may include Windows, Unix, Linux, etc. Data 203 may include but is not limited to overvoltage protection methods, etc.

[0125] In some embodiments, the electronic device may further include a display screen 22 , an input / output interface 23 , a communication interface 24 , a power source 25 , and a communication bus 26 .

[0126] Those skilled in the art will understand that Fig. 9 The structure shown in the figure does not constitute a limitation on the electronic device, and may include more or fewer components than shown in the figure.

[0127] The purpose of this embodiment is to provide an electronic device, in which the memory 20 is used to store computer programs, and the processor 21 is used to implement the steps of the above-mentioned overvoltage protection method when executing the computer program, so that the overvoltage protection process is more efficient and accurate.

[0128] The present invention also provides an embodiment corresponding to a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the overvoltage protection method described above are implemented.

[0129] It is understandable that if the method in the above embodiment is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium to execute all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program codes.

[0130] The computer-readable storage medium provided in this embodiment corresponds to the above method, and therefore has the same beneficial effects as the above method. Therefore, for the embodiments of the computer-readable storage medium part, please refer to the description of the embodiments of the method part, which will not be repeated here.

[0131] It should be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0132] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An overvoltage protection method, characterized in that: include: Obtaining a rated protection voltage value when any IGBT in the converter of the wind turbine generator set is in operation, and using the rated protection voltage value as a PWM wave envelope value of each IGBT, wherein the converter comprises: a rotor-side converter and a grid-side converter, and the rated protection voltage values ​​of each IGBT in operation are equal; Setting a first overvoltage fault protection value of a DC bus capacitor corresponding to the converter according to the PWM wave-enclosing value, wherein the first overvoltage fault protection value is greater than the PWM wave-enclosing value, and the first overvoltage fault protection value meets the voltage protection requirements of the DC bus capacitor and each of the IGBTs in the off state; Collecting the current voltage value of the DC bus capacitor, and determining whether the current voltage value is greater than the PWM wave-sealing value; If the current voltage value is greater than the PWM envelope value, a shutdown signal is sent to each IGBT in the rotor-side converter and the grid-side converter to control each IGBT to shut down, and determine whether the current voltage value is greater than the first overvoltage fault protection value; If the current voltage value is greater than the first overvoltage fault protection value, it is determined that an overvoltage fault occurs in the DC bus capacitor, and the wind turbine is controlled to be disconnected from the power grid.

2. The overvoltage protection method according to claim 1, characterized in that: Controlling each of the IGBTs to turn off, comprising: Continuously sending the shutdown signal to each of the IGBTs within a first preset time period to control each of the IGBTs to shut down; After controlling each of the IGBTs to turn off, the method further includes: collecting the voltage of the DC bus capacitor after the first preset time period; Determining whether the voltage of the DC bus capacitor after the first preset time period is less than the PWM wave-sealing value; If the voltage of the DC bus capacitor after the first preset time period is less than the PWM envelope value, a start signal is sent to each of the IGBTs to control each of the IGBTs to turn on.

3. The overvoltage protection method according to claim 1, characterized in that: After controlling each of the IGBTs to turn off, the method further includes: Determining an actual turn-off time of each of the IGBTs; Determine whether the actual shutdown time is greater than a preset shutdown time threshold; If the actual shutdown time is greater than the preset shutdown time threshold, it is determined that a long blocking time fault occurs in each of the IGBTs, and the wind turbine is controlled to shut down.

4. The overvoltage protection method according to claim 3, characterized in that: Determining the actual turn-off time of each IGBT includes: Determine the first moment when the current voltage value is equal to the PWM envelope value for the first time; Determine a second moment when the current voltage value is equal to the PWM envelope value for the second time; The actual turn-off time is determined according to the difference between the second moment and the first moment.

5. The overvoltage protection method according to claim 1, characterized in that: Also includes: Obtaining a current value of the DC bus capacitor; Determining whether the current value is greater than a preset current threshold; If the current current value is greater than the preset current threshold, the shutdown signal is sent to each IGBT in the rotor-side converter and the grid-side converter to control each IGBT to be shut down.

6. The overvoltage protection method according to any one of claims 1 to 5, characterized in that: Before determining whether the current voltage value is greater than the first overvoltage fault protection value, the method further includes: The second overvoltage fault protection value of the DC bus capacitor is set according to the first overvoltage fault protection value and the PWM wave-enclosing value, wherein the second overvoltage fault protection value is greater than the PWM wave-enclosing value, and the second overvoltage fault protection value is less than the first overvoltage fault protection value; Determining whether the current voltage value is greater than the second overvoltage fault protection value; If the current voltage value is greater than the second overvoltage fault protection value, a step of determining whether the current voltage value is greater than the first overvoltage fault protection value is triggered.

7. The overvoltage protection method according to claim 6, characterized in that: After the current voltage value is greater than the second overvoltage fault protection value, the method further includes: Determining whether the voltage of the power grid is less than a preset voltage threshold within a second preset time period; If the voltage of the power grid is less than a preset voltage threshold value within a second preset time period, until the voltage of the power grid is not less than the preset voltage threshold value, triggering the step of collecting the current voltage value of the DC bus capacitor and determining whether the current voltage value is greater than the PWM wave value; If the voltage of the power grid is not less than the preset voltage threshold within the second preset time period, the step of determining whether the current voltage value is greater than the first overvoltage fault protection value is triggered.

8. An overvoltage protection device, Its characteristics include: An acquisition unit is used to acquire a rated protection voltage value when any IGBT in a converter in a wind turbine generator set is in operation, and use the rated protection voltage value as a PWM wave envelope value of each IGBT, wherein the converter includes: a rotor-side converter and a grid-side converter, and the rated protection voltage values ​​of each IGBT in operation are equal; A setting unit, configured to set a first overvoltage fault protection value of a DC bus capacitor corresponding to the converter according to the PWM wave-enclosing value, wherein the first overvoltage fault protection value is greater than the PWM wave-enclosing value, and the first overvoltage fault protection value satisfies a voltage protection requirement of the DC bus capacitor and each of the IGBTs in a shutdown state; A collection unit, used for collecting the current voltage value of the DC bus capacitor and determining whether the current voltage value is greater than the PWM wave-sealing value; a first determination unit, configured to send a shutdown signal to each IGBT in the rotor-side converter and the grid-side converter to control each IGBT to shut down when the current voltage value is greater than the PWM envelope value, and to determine whether the current voltage value is greater than the first overvoltage fault protection value; The second determination unit is used to determine that an overvoltage fault occurs in the DC bus capacitor when the current voltage value is greater than the first overvoltage fault protection value, and to control the wind turbine to be disconnected from the power grid.

9. An electronic device, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the overvoltage protection method according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the overvoltage protection method according to any one of claims 1 to 7 are implemented.

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