A Fault Ride-Through Fast Detection and Control Method, Device and Equipment for a New Energy Unit

Abstract

The present invention relates to the technical field of power grid maintenance, and particularly to a method, device and equipment for quickly detecting and controlling the fault ride-through of new energy units. The method includes: setting a sampling interval time, and performing three-phase grid connection point voltage acquisition and processing of the new energy unit once every sampling interval time; analyzing the grid connection point voltage situation at the current moment with the first positive sequence component value obtained from the N dq components closest to the current moment and the second positive sequence component value obtained from the N dq components before the N dq components closest to the current moment; judging the specific overvoltage state and whether it is in the overvoltage fault ride-through, and executing a voltage regulation strategy, so that the detection delay of each execution of the voltage regulation strategy is controlled within the total time of obtaining 2N dq components, reducing the delay time while ensuring the detection accuracy, alleviating the overvoltage reverse regulation situation, and improving the operation stability and reliability of the power grid.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid maintenance, and in particular to a method, device and equipment for rapid detection and control of fault ride-through of a new energy generator set. Background Art

[0002] As the scale of renewable energy units connected to the power grid becomes larger and larger, the interactive coupling of DC and renewable energy characteristics in the renewable energy DC transmission system makes the voltage of the sending-end system more complex, resulting in increasingly serious transient overvoltage problems.

[0003] To ensure stability in overvoltage conditions, the inverter controls the active and reactive currents and takes corresponding control measures based on changes in the terminal voltage. However, due to the existence of measurement and filtering links, the inverter responds to grid voltage changes with a delay of approximately 10 to 20 ms. When the grid experiences continuous undervoltage or overvoltage faults, the delay can easily lead to the execution of high-voltage measures under low-voltage conditions, or the execution of low-voltage measures under high-voltage conditions, resulting in an overvoltage "reverse regulation" phenomenon, further reducing the stability and reliability of the grid. Summary of the Invention

[0004] The present invention provides a new energy unit fault ride-through rapid detection and control method for solving the problem in the prior art of high delay in responding to grid voltage changes, resulting in overvoltage reverse regulation and reduced grid temperature and reliability.

[0005] A first aspect of the present invention provides a method for rapid detection and control of fault ride-through of a new energy generator set, comprising:

[0006] A sampling interval is set, and every time the sampling interval passes, the three-phase grid-connected point voltage of the new energy unit is collected; the collected three-phase grid-connected point voltage is normalized and instantaneously decomposed into dq to obtain the dq components at the corresponding sampling time;

[0007] After each new dq component is obtained, the average values of the 1st to Nth dq components whose sampling times are closest to the current time are calculated to obtain the first active component average value and the first reactive component average value, and the square root of the sum of the squares of the two is calculated to obtain the first positive-sequence component value; the average values of the N+1th to 2Nth dq components whose sampling times are closest to the current time are calculated to obtain the second active component average value and the second reactive component average value, and the square root of the sum of the squares of the two is calculated to obtain the second positive-sequence component value; the product of the sampling interval and 2N is less than or equal to a response threshold; the response threshold is the maximum delay time that will not cause reverse regulation when continuous voltage fluctuations occur in the power grid;

[0008] Obtain the voltage change condition based on the positive or negative of the difference between the first positive sequence component value and the second positive sequence component value; obtain the type of crossing according to the magnitude of the second positive sequence component value relative to the voltage component standard value, and determine whether to enter the corresponding fault state with the hysteresis threshold corresponding to the type of crossing;

[0009] Make a judgment based on the voltage change condition and the fault state. If the type of crossing is high-voltage crossing, enter the fault state and the voltage change condition is increasing, or the type of crossing is low-voltage crossing, enter the fault state and the voltage change condition is decreasing, then perform voltage regulation.

[0010] Optionally, the determining the voltage change condition according to the positive or negative of the difference between the first positive sequence component value and the second positive sequence component value specifically includes:

[0011] Calculate the voltage change rate between the first positive sequence component value and the second positive sequence component value. If the voltage change rate is positive, it indicates that the voltage change trend is increasing. If the voltage change rate is negative, it indicates that the voltage change trend is decreasing.

[0012] Optionally, the determining whether to enter the corresponding fault state with the hysteresis threshold corresponding to the type of crossing specifically includes:

[0013] In the case of low-voltage crossing, subtract the low-voltage fault threshold from the second positive sequence component value. If the difference is greater than or equal to the low-voltage hysteresis threshold, enter the low-voltage fault state; in the case of high-voltage crossing, subtract the high-voltage fault threshold from the positive sequence component value. If the difference is less than or equal to the high-voltage hysteresis threshold, enter the high-voltage fault state.

[0014] Optionally, the performing voltage regulation is specifically: calculate the fault reactive power support current value, and set the reactive current reference value of the new energy unit to the fault reactive power support current value. The calculation model of the fault reactive power support current value is:

[0015]

[0016] In the formula, K r is the voltage change rate, ΔV is the voltage hysteresis threshold corresponding to the type of fault crossing, K is the reactive power support coefficient, I qnom is the reactive current reference value without fault.

[0017] Optionally, after the performing voltage regulation, it further includes: if it recovers from the high-voltage fault state to the fault-free state and the voltage change condition is decreasing, or if it recovers from the low-voltage fault state to the fault-free state and the voltage change condition is increasing, then terminate the voltage regulation.

[0018] Optionally, the per-unit value processing specifically involves substituting the instantaneous nominal values of the three-phase voltages at the three-phase grid connection point into the per-unit value processing model to obtain the corresponding per-unit values of the three-phase instantaneous voltages. The per-unit value processing model is specifically as follows:

[0019]

[0020] In the formula, U pcci is the per-unit value of the three-phase instantaneous voltage, u pcci is the instantaneous nominal value of the three-phase voltage, and U r is the rated peak value of the voltage.

[0021] Optionally, the instantaneous dq decomposition specifically involves substituting the per-unit values of the three-phase instantaneous voltages into the instantaneous dq decomposition model to obtain the active component V d and the reactive component V q . The instantaneous dq decomposition model is specifically as follows:

[0022]

[0023] In the formula, V d is the active component, and V q is the reactive component; ω is the grid synchronous angular frequency. [[ID=3I]]

[0024] Optionally, after obtaining the second positive sequence component value, if the number of sampled dq components cannot meet the calculation requirements of the first positive sequence component value or the second positive sequence component value, the un-sampled dq components are replaced with preset standard values.

[0025] The second aspect of the present application provides a new energy unit fault ride-through fast detection and control device, including:

[0026] A data sampling module, which is used to set the sampling interval time, and perform a three-phase grid connection point voltage acquisition of the new energy unit every time the sampling interval time elapses; perform per-unit value processing and instantaneous dq decomposition on the acquired three-phase grid connection point voltage to obtain the dq components at the corresponding sampling moment;

[0027] A positive sequence component value calculation module, which is used to, after obtaining new dq components each time, calculate the average value of the 1st to Nth dq components whose sampling moments are closest to the current moment according to the sampling moment sorting, obtain the first active component average value and the first reactive component average value, calculate the square root of the sum of their squares to obtain the first positive sequence component value; calculate the average value of the (N + 1)th to 2Nth dq components whose sampling moments are closest to the current moment, obtain the second active component average value and the second reactive component average value, calculate the square root of the sum of their squares to obtain the second positive sequence component value; the product of the sampling interval time and 2N is less than or equal to the response threshold; the response threshold is the maximum delay time that will not cause reverse regulation when the grid undergoes continuous voltage fluctuations;

[0028] A fault judgment and recognition module, configured to obtain the voltage change situation according to the positive or negative of the difference between the first positive sequence component value and the second positive sequence component value; obtain the crossing type according to the magnitude of the second positive sequence component value relative to the voltage component standard value, and judge whether to enter the corresponding fault state with the hysteresis threshold corresponding to the crossing type.

[0029] A voltage regulation and stability control module, configured to make a judgment according to the voltage change situation and the fault state. If the crossing type is high-voltage crossing, enter the fault state and the voltage change situation is increasing, or the crossing type is low-voltage crossing, enter the fault state and the voltage change situation is decreasing, perform voltage regulation.

[0030] The third aspect of the present application provides a new energy unit fault crossing rapid detection and control device, and the device includes a processor and a memory:

[0031] The memory is used to store program codes and transmit the program codes to the processor;

[0032] The processor is used to execute the new energy unit fault crossing rapid detection and control method according to any one of the first aspects of the present invention according to the instructions in the program codes.

[0033] It can be seen from the above technical solutions that the present invention has the following advantages: By setting the sampling interval time, and performing three-phase grid connection point voltage acquisition and processing of the new energy unit once every sampling interval time; using the first positive sequence component value obtained from the N dq components closest to the current moment and the second positive sequence component value obtained from the N dq components before the N dq components closest to the current moment to analyze the grid connection point voltage situation at the current moment; judging the specific overvoltage state and whether it is in the overvoltage fault crossing, and then executing the voltage regulation strategy, so that the detection delay of each execution of the voltage regulation strategy is controlled within the total time of obtaining 2N dq components. While ensuring the detection accuracy, the delay time is reduced, the overvoltage reverse regulation situation is alleviated, and the grid operation stability and reliability are improved. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings.

[0035] Figure 1 It is the first flowchart of the new energy unit fault crossing rapid detection and control method;

[0036] Figure 2 It is the second flowchart of the fast detection and control method for the fault ride-through of new energy units;

[0037] Figure 3 It is the third flowchart of the fast detection and control method for the fault ride-through of new energy units;

[0038] Figure 4 It is the diagram of the fast detection and control device for the fault ride-through of new energy units. Specific implementation manners

[0039] In order to make the invention purpose, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0040] The present invention provides a fast detection and control method for the fault ride-through of new energy units, which is used to solve the problems in the prior art that due to the high delay in responding to the change of the grid voltage, overvoltage reverse regulation occurs, reducing the grid temperature and reliability.

[0041] Please refer to Figure 1 , Figure 1 It is the first flowchart of the fast detection and control method for the fault ride-through of new energy units provided by the embodiments of the present invention.

[0042] S100, set the sampling interval time, and perform a three-phase grid connection point voltage acquisition of the new energy unit every time the sampling interval time elapses; perform per-unit conversion and instantaneous dq decomposition on the collected three-phase grid connection point voltage to obtain the dq components at the corresponding sampling moments;

[0043] It should be noted that after performing per-unit conversion on the three-phase grid connection point voltage, the unit levels of each phase voltage are unified, and then instantaneous dq decomposition is performed to decompose the voltage value change into active and reactive components; by performing sampling, per-unit conversion, and instantaneous dq decomposition every time the sampling interval time elapses, the dq components at several sampling moments are obtained.

[0044] S200, after each new dq component is obtained, sorting by sampling time, calculating the average value of the 1st to Nth dq components whose sampling times are closest to the current time, obtaining a first active component average value and a first reactive component average value, calculating the square root of the sum of the squares of the two, and obtaining a first positive-sequence component value; calculating the average value of the N+1th to 2Nth dq components whose sampling times are closest to the current time, obtaining a second active component average value and a second reactive component average value, and calculating the square root of the sum of the squares of the two, and obtaining a second positive-sequence component value; the product of the sampling interval and 2N is less than or equal to a response threshold; the response threshold is the maximum delay time that will not cause reverse regulation when continuous voltage fluctuations occur in the power grid;

[0045] It should be noted that, starting from the most recently collected dq component in chronological order, they are numbered 1 to 2N in sequence. The active component and reactive component in the 1st to Nth dq components are summed and divided by N to obtain the first active component average value and the first reactive component average value; the active component and reactive component in the N+1th to 2Nth dq components are summed and divided by N to obtain the second active component average value and the second reactive component average value; and each time a new dq component is obtained, the new first positive sequence component value and second positive sequence component value at the current moment can be calculated;

[0046] The product of the sampling interval and 2N corresponds to the time span of the first positive-sequence component value and the second positive-sequence component value. The product of the sampling interval and 2N is limited to be less than or equal to the response threshold. The response threshold is the maximum delay time that will not cause reverse regulation when continuous voltage fluctuations occur in the power grid. Therefore, when the voltage regulation judgment is performed in the subsequent steps based on the first positive-sequence component value and the second positive-sequence component value, the overall judgment time is less than or equal to the response threshold. In actual implementation, the specific values of the sampling interval and 2N are set according to the actual detection situation, and N is a positive integer. The response threshold is generally set to 2ms and can be adjusted according to actual response requirements.

[0047] At step S300, a voltage change is determined based on the sign of the difference between the first positive sequence component value and the second positive sequence component value; a ride-through type is determined based on the magnitude of the second positive sequence component value relative to a standard voltage component value; and a hysteresis threshold corresponding to the ride-through type is used to determine whether a corresponding fault state has occurred.

[0048] It should be noted that the sampling time corresponding to the first positive sequence component value is later than that of the second positive sequence component value. Therefore, the positive or negative value of the difference between the first positive sequence component value and the second positive sequence component value can reflect whether the voltage is increasing or decreasing. To ensure the continuous operation of the new energy unit without disconnecting from the grid, when the second positive sequence component value is greater than the voltage component standard value, the new energy unit will enter high-voltage ride-through. When the second positive sequence component value is smaller than the voltage component standard value, the new energy unit will enter low-voltage ride-through. The hysteresis thresholds used for hysteresis judgment under corresponding high and low voltage ride-throughs are different. After hysteresis judgment, it can be determined whether to enter the corresponding high-voltage fault or low-voltage fault during the fault ride-through process. The specific voltage classification standard value and hysteresis threshold are set according to specific requirements.

[0049] S400. Judge according to the voltage change situation and the fault state. If the ride-through type is high-voltage ride-through, enter the fault state and the voltage change situation is increasing, or the ride-through type is low-voltage ride-through, enter the fault state and the voltage change situation is decreasing, perform voltage regulation.

[0050] It should be noted that based on the fact that the times corresponding to the obtained fault state and voltage change situation are continuous and one before the other, when judging in combination with the fault state and voltage change situation, in the case of a high-voltage fault state and an increasing voltage change situation, it indicates that the grid voltage is still increasing under the high-voltage fault, that is, it indicates that voltage reduction regulation needs to be performed. In the case of a low-voltage fault state and a decreasing voltage change situation, it indicates that the grid voltage is still decreasing under the low-voltage fault, that is, it indicates that voltage increase regulation needs to be performed.

[0051] In this embodiment, by setting the sampling interval time, and every time the sampling interval time elapses, the three-phase grid connection point voltage of the new energy unit is collected and processed. The first positive sequence component value obtained from the N dq components closest to the current moment and the second positive sequence component value obtained from the N dq components before the N dq components closest to the current moment are used to analyze the grid connection point voltage situation at the current moment. Judge the specific overvoltage state and whether it is in the overvoltage fault ride-through, and execute the voltage regulation strategy, so that the detection delay of each execution of the voltage regulation strategy is controlled within the total time of obtaining 2N dq components. While ensuring the detection accuracy, the delay time is reduced, the overvoltage reverse regulation situation is alleviated, and the operation stability and reliability of the power grid are improved.

[0052] The above is the detailed description of the first embodiment of a method for quickly detecting and controlling the fault ride-through of a new energy unit provided by this application. The following is the detailed description of the second embodiment of a method for quickly detecting and controlling the fault ride-through of a new energy unit provided by this application.

[0053] In this embodiment, a specific embodiment of a method for quickly detecting and controlling the fault ride-through of a new energy unit is further provided. Please refer to Figure 2 In step S300 of the foregoing embodiment, steps S301 - S303 are specifically included, and the details are as follows:

[0054] S301, calculate the voltage change rate between the first positive sequence component value and the second positive sequence component value. If the voltage change rate is positive, set the first state value to 1. If the voltage change rate is negative, set the first state value to -1;

[0055] It should be noted that let the first positive sequence component value be Y pos1 The second positive sequence component value be V pos2 , and the calculation model of the voltage change rate is:

[0056]

[0057] In the formula, K r is the voltage change rate, and Δt is the sampling interval time;

[0058] The positive or negative of the voltage change rate is equivalent to the positive or negative of the difference between the first positive sequence component value and the second positive sequence component value. Being positive indicates that the voltage change trend is increasing, and being negative indicates that the voltage change trend is decreasing; after setting the first state value F1 according to the positive or negative of the voltage change rate, the voltage change situation can be directly determined according to the first state value in the subsequent steps of judging and performing voltage regulation;

[0059] Furthermore, if the voltage change rate is zero, set the first state value to 0, indicating that the voltage remains stable at this time.

[0060] S302, subtract the second positive sequence component value from the voltage component standard value. If the difference is positive, it is in high voltage ride-through. If the difference is negative, it is in low voltage ride-through;

[0061] It should be noted that the grid-connected voltage has a preset calibration value, which is the voltage component standard value. When the second positive sequence component value fluctuates due to grid disturbances and the power station can still operate continuously without tripping, it is the voltage ride-through situation. At this time, according to the positive or negative relative to the standard value, it is judged whether the fluctuation in this ride-through situation is a high voltage or a low voltage, so as to guide subsequent calculations and judgments.

[0062] S303, in the case of low voltage ride-through, subtract the low voltage fault threshold from the second positive sequence component value. If the difference is greater than or equal to the low voltage hysteresis threshold, set the second state value to 1. If not, set the second state value to 0; in the case of high voltage ride-through, subtract the high voltage fault threshold from the positive sequence component value. If the difference is less than or equal to the high voltage hysteresis threshold, set the second state value to -1. If not, set the second state value to 0;

[0063] It should be noted that the fault threshold and the hysteresis threshold adopted in different voltage ride-through situations are different. During specific implementation, the low-voltage fault threshold V lref can be set to 0.9, and the low-voltage hysteresis threshold ΔV l can be set to 0.01. The high-voltage fault threshold V href can be set to 1.1, and the high-voltage hysteresis threshold ΔV h can be set to -0.01. The specific threshold settings are adjusted according to actual requirements. After setting the second state value F2 according to the hysteresis judgment, during the subsequent steps of judging and performing voltage regulation, it can be directly determined whether it is in a fault state and the specific type of ride-through according to the second state value.

[0064] Please refer to Figure 3 , in step S400 of the foregoing embodiment, it specifically includes steps S401 - S402, and the details are as follows:

[0065] S401, set the fault flag bit and the current transmission flag bit according to the changes of the first state value and the second state value. If the first state value is -1 and the second state value was 0 at the previous moment and is 1 at the current moment, then set the current transmission flag bit CTR to 1 and the low-voltage fault flag bit LCTR to 1; if the second state value is 1 and the first state value was 0 at the previous moment and is -1 at the current moment, then set the current transmission flag bit CTR to 1 and the high-voltage fault flag bit HCTR to 1;

[0066] It should be noted that by the change of the second state value between the previous moment and the current moment, it is judged whether the current voltage change enters the fault ride-through situation from a non-fault state, and then combined with the first state value, it is judged whether the voltage change conforms to the corresponding high-voltage or low-voltage ride-through, so as to determine that a fault state has been entered.

[0067] Furthermore, if the first state value is 1 and the second state value was 1 at the previous moment and is 0 at the current moment, it indicates that the low-voltage fault ride-through has recovered, then set the current transmission flag bit CTR to 0 and the low-voltage fault flag bit LCTR to 0, indicating that the current moment is normal; if the second state value is -1 and the first state value was -1 at the previous moment and is 0 at the current moment, it indicates that the high-voltage fault ride-through has recovered, then set the current transmission flag bit CTR to 0 and the high-voltage fault flag bit HCTR to 0, indicating that the current moment is normal.

[0068] S402, perform voltage regulation according to the current transmission flag bit CTR.

[0069] It should be noted that when the current transmission flag bit CTR is 1, it represents that there is a fault ride-through situation in the power grid, and voltage regulation needs to be performed. Set the reactive current reference value I qref0 to the fault reactive support current value I qf; When the current transmission flag bit CTR is 0, it means that the grid output has returned to a steady state, there is no need to perform voltage regulation, the voltage regulation strategy is terminated, and the reactive current reference value I of the new energy unit is qref0 set to the fault-free reactive current reference value I qnom That's it. The fault-free reactive current reference value is calculated by the constant reactive power outer loop or the constant voltage outer loop.

[0070] Furthermore, the calculation model of the fault reactive support current value I qf is specifically as follows:

[0071]

[0072] In the formula, K r is the voltage change rate, ΔV is the voltage hysteresis threshold corresponding to the fault crossing type, and K is the reactive power support coefficient, which is taken between 1.5 and 3 according to the fault flag bit as required by the national standard.

[0073] Furthermore, in a more specific embodiment, the per-unit conversion process of the foregoing step S100 is specifically to substitute the three-phase instantaneous nominal values of the three-phase grid connection point voltage into the per-unit conversion model respectively to obtain the corresponding three-phase instantaneous voltage per-unit values. The per-unit conversion model is specifically as follows:

[0074]

[0075] In the formula, U pcci is the three-phase instantaneous voltage per-unit value, u pcci is the three-phase instantaneous nominal value of the voltage, and U r is the rated peak value of the voltage;

[0076] Furthermore, the instantaneous dq decomposition is specifically to substitute the three-phase instantaneous voltage per-unit value into the instantaneous dq decomposition model to obtain the active component V d and the reactive component V q , and the instantaneous dq decomposition model is specifically as follows:

[0077]

[0078] In the formula, V d is the active component, and V q is the reactive component; ω is the grid synchronous angular frequency, which can be obtained by the phase-locked loop PLL. Since the grid frequency changes very little, ω can be updated at a certain interval. In actual implementation, it can be updated once every 10 minutes. Before the update, ω can be considered to remain unchanged to reduce the impact of the PLL dynamic process on the detection.

[0079] Further, in the initial stage of detection control, when the number of dq components obtained by sampling calculation does not meet N or 2N, a preset standard value can be used to replace the unsampled dq components, and the preset standard value is set according to the value during the actual stable operation of the power grid.

[0080] In this embodiment, by processing the first positive sequence component value and the second positive sequence component value, the specific situation of the power grid voltage change is analyzed, and the fault reactive power support current is set based on the average voltage change rate within two threshold time periods, improving the accuracy and effect of voltage regulation in the voltage regulation strategy, and further improving the stability and reliability of the power grid.

[0081] The above is the detailed description of the second embodiment of a new energy unit fault ride-through fast detection and control method provided by this application. Next is the detailed description of a new energy unit fault ride-through fast detection and control device provided by the second aspect of this application.

[0082] Please refer to Figure 4 , Figure 4 which is the diagram of the new energy unit fault ride-through fast detection and control device. This embodiment provides a new energy unit fault ride-through fast detection and control device, including:

[0083] A data sampling module 10, configured to set a sampling interval time, and perform a three-phase grid connection point voltage acquisition of the new energy unit every time the sampling interval time elapses; perform per-unit conversion processing and instantaneous dq decomposition on the acquired three-phase grid connection point voltage to obtain dq components at the corresponding sampling moments;

[0084] A positive sequence component value calculation module 20, configured to, after obtaining a new dq component each time, calculate the average value of the 1st to Nth dq components whose sampling moments are closest to the current moment according to the sampling moment sorting, obtain the first active component average value and the first reactive component average value, calculate the square root of the sum of the squares of the two, and obtain the first positive sequence component value; calculate the average value of the (N + 1)th to 2Nth dq components whose sampling moments are closest to the current moment, obtain the second active component average value and the second reactive component average value, calculate the square root of the sum of the squares of the two, and obtain the second positive sequence component value; the product of the sampling interval time and 2N is less than or equal to the response threshold; the response threshold is the maximum delay time when continuous voltage fluctuations in the power grid will not cause reverse regulation;

[0085] A fault judgment and identification module 30, configured to obtain the voltage change situation according to the positive or negative of the difference between the first positive sequence component value and the second positive sequence component value; obtain the crossing type according to the magnitude of the second positive sequence component value relative to the voltage component standard value, and judge whether to enter the corresponding fault state with the hysteresis threshold corresponding to the crossing type;

[0086] The voltage regulation and stability control module 40 is used to make a judgment according to the voltage change situation and the fault state. If the crossing type is high-voltage crossing, entering the fault state and the voltage change situation is increasing, or the crossing type is low-voltage crossing, entering the fault state and the voltage change situation is decreasing, voltage regulation is executed.

[0087] The third aspect of this application also provides a new energy unit fault crossing rapid detection and control device, including a processor and a memory: The memory is used to store program codes and transmit the program codes to the processor; the processor is used to execute the above-mentioned new energy unit fault crossing rapid detection and control method according to the instructions in the program codes.

[0088] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the above-described devices and equipment can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0089] In several embodiments provided by this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection can be through some interfaces. The indirect coupling or communication connection of the device or unit can be in electrical, mechanical or other forms.

[0090] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0091] In addition, in each embodiment of the present invention, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0092] When the integrated unit 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, in essence, 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. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs.

[0093] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A rapid detection and control method for a new energy unit to ride through faults, characterized in that Including: Set the sampling interval time, and perform three-phase grid connection point voltage acquisition of the new energy unit once every sampling interval time; Perform per-unit conversion and instantaneous dq decomposition on the acquired three-phase grid connection point voltage to obtain the dq components at the corresponding sampling moment; After obtaining a new dq component each time, according to the sampling moment sorting, calculate the average value of the 1st to Nth dq components whose sampling moments are closest to the current moment to obtain the first active component average value and the first reactive component average value, and calculate the square root of the sum of the squares of the two to obtain the first positive sequence component value; Calculate the average value of the (N + 1)th to 2Nth dq components whose sampling moments are closest to the current moment to obtain the second active component average value and the second reactive component average value, and calculate the square root of the sum of the squares of the two to obtain the second positive sequence component value; the product of the sampling interval time and 2N is less than or equal to the response threshold; the response threshold is the maximum delay time when continuous voltage fluctuations in the power grid will not cause reverse regulation; Obtain the voltage change situation according to the positive or negative of the difference between the first positive sequence component value and the second positive sequence component value; obtain the crossing type according to the magnitude of the second positive sequence component value relative to the voltage component standard value, and judge whether to enter the corresponding fault state with the hysteresis threshold corresponding to the crossing type; Make a judgment according to the voltage change situation and the fault state. If the crossing type is high voltage crossing, enter the fault state and the voltage change situation is increasing, or the crossing type is low voltage crossing, enter the fault state and the voltage change situation is decreasing, perform voltage regulation.

2. The method for quickly detecting and controlling the fault ride-through of a new energy unit according to claim 1, characterized in that The specific method of judging the voltage change situation according to the positive or negative of the difference between the first positive sequence component value and the second positive sequence component value includes: Calculate the voltage change rate between the first positive sequence component value and the second positive sequence component value. If the voltage change rate is positive, it means that the voltage change trend is increasing. If the voltage change rate is negative, it means that the voltage change trend is decreasing.

3. A method for quickly detecting and controlling a new energy unit's fault ride-through, according to claim 1, characterized in that The specific method of judging whether to enter the corresponding fault state with the hysteresis threshold corresponding to the crossing type includes: In the case of low voltage crossing, subtract the low voltage fault threshold from the second positive sequence component value. If the difference is greater than or equal to the low voltage hysteresis threshold, enter the low voltage fault state; in the case of high voltage crossing, subtract the high voltage fault threshold from the positive sequence component value. If the difference is less than or equal to the high voltage hysteresis threshold, enter the high voltage fault state.

4. A method for quickly detecting and controlling the fault ride-through of a new energy unit according to claim 1, characterized in that, The specific implementation of the voltage regulation is: calculate the fault reactive power support current value, and set the reactive current reference value of the new energy unit to the fault reactive power support current value. The calculation model of the fault reactive power support current value is: Where, K r is the voltage change rate, ΔV is the voltage hysteresis threshold corresponding to the type of fault ride-through, K is the reactive power support coefficient, and I qnom is the reference value of the non-fault reactive current.

5. A method for quickly detecting and controlling the fault ride-through of a new energy unit according to claim 1, characterized in that, After performing the voltage regulation, it further includes: if it recovers from the high voltage fault state to the fault-free state and the voltage change situation is decreasing, or if it recovers from the low voltage fault state to the fault-free state and the voltage change situation is increasing, terminate the voltage regulation.

6. A fault ride-through rapid detection and control method for a new energy unit according to claim 1, characterized in that, The per-unit conversion is specifically to substitute the three-phase voltage instantaneous nominal values of the three-phase grid connection point voltage into the per-unit conversion model respectively to obtain the corresponding three-phase instantaneous voltage per-unit values. The per-unit conversion model is specifically: Where U pcci is the per-unit value of the three-phase instantaneous voltage, u pcci is the instantaneous nominal value of the three-phase voltage, and U r is the rated peak value of the voltage.

7. A method for quickly detecting and controlling the fault ride-through of a new energy unit according to claim 6, characterized in that The specific instantaneous dq decomposition is to substitute the per-unit values of the three-phase instantaneous voltages into the instantaneous dq decomposition model to obtain the active component V d and the reactive component V q . The specific instantaneous dq decomposition model is as follows: where V d is the active component, and V q is the reactive component; ω is the grid synchronous angular frequency.

8. The method for quickly detecting and controlling the fault ride-through of the new energy unit according to claim 1, characterized in that, After obtaining the second positive sequence component value, it further includes that if the number of dq components obtained by sampling calculation cannot meet the calculation of the first positive sequence component value or the second positive sequence component value, the non-sampled dq components are replaced with preset standard values.

9. A fast detection and control device for a new energy unit to ride through faults, characterized in that, It includes: A data sampling module, configured to set a sampling interval time, and perform three-phase grid connection point voltage acquisition of a new energy unit every time the sampling interval time elapses; Perform per-unit processing and instantaneous dq decomposition on the acquired three-phase grid connection point voltage to obtain dq components at the corresponding sampling moment; A positive sequence component value calculation module, configured to, after obtaining a new dq component each time, calculate the average value of the 1st to Nth dq components whose sampling moments are closest to the current moment according to the sampling moment sorting, obtain the first active component average value and the first reactive component average value, calculate the square root of the sum of the squares of the two, and obtain the first positive sequence component value; Calculate the average value of the (N + 1)th to 2Nth dq components whose sampling moments are closest to the current moment, obtain the second active component average value and the second reactive component average value, calculate the square root of the sum of the squares of the two, and obtain the second positive sequence component value; the product of the sampling interval time and 2N is less than or equal to the response threshold; The response threshold is the maximum delay time that will not cause reverse regulation when continuous voltage fluctuations occur in the power grid; A fault judgment and identification module, configured to obtain the voltage change situation according to the positive or negative of the difference between the first positive sequence component value and the second positive sequence component value; obtain the crossing type according to the magnitude of the second positive sequence component value relative to the voltage component standard value, and judge whether to enter the corresponding fault state with the hysteresis threshold corresponding to the crossing type; A voltage regulation and stability control module, configured to make a judgment according to the voltage change situation and the fault state. If the crossing type is high voltage crossing, enter the fault state and the voltage change situation is increasing, or the crossing type is low voltage crossing, enter the fault state and the voltage change situation is decreasing, perform voltage regulation.

10. A new energy unit fault ride-through rapid detection and control device, characterized in that, The device includes a processor and a memory: The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the method according to any one of claims 1 - 8 according to the instructions in the program codes.

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