Staged grouping method and system for whole wind power plant fault process and electronic equipment

Abstract

The invention discloses a staged grouping method and system for a whole wind power plant fault process and electronic equipment, and the method comprises the steps: carrying out the grouping equivalence of a whole wind power plant group based on a slip ratio and an rsc inner ring proportionality coefficient of a rotor-side converter in an unreacted stage of a converter; when at least one fan action enters a crowbar protection Crowbar input-asynchronous machine stage, performing initial classification on a whole fan group based on whether the fan action exists, and performing grouping equivalence based on a slip ratio and an inner ring proportionality coefficient of a rotor side converter on the basis of an initial classification result; and when the Crowbar exits and all the fans return to the rsc control stage, keeping the grouping result until the fault is removed. According to the method, the wind power plant short-circuit current dynamic characteristics in the whole fault process can be accurately described, accurate calculation of the wind power plant short-circuit current is achieved, and technical support is provided for high-proportion new energy power system short-circuit calculation and wind power plant equivalent grouping.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system relay protection, and more particularly, to a wind farm fault whole-process phased grouping method, system and electronic equipment. BACKGROUND

[0002] Under the "double carbon" goal, accelerating the replacement of traditional fossil energy power generation with new energy power generation and building a new power system with gradually increasing new energy proportion has become the main direction of the development of China's power system. The proportion of wind power and photovoltaic power generation is increasing. The current calculation method for short-circuit current after the access of new energy farm group mainly includes: first, based on the fault response mechanism of a single unit, the short-circuit current calculation model of the unit group is derived; second, based on the difference law of the fault transient characteristics of the unit group, the electromagnetic transient aggregation model of the large-scale unit group is established. In terms of short-circuit calculation model of unit group, some methods are based on the operation mode that Crowbar circuit is always put into during fault, and by analyzing the transient behavior characteristics of DFIG unit, the short-circuit current calculation method of wind power unit group is derived. Some methods derive the short-circuit current calculation model of wind power unit group by studying the steady-state fault response characteristics of DFIG unit under the control of rotor converter. The above methods all assume that DFIG unit group is in the same operation control mode under fault, and do not consider the difference of operation control mode of unit group. At the same time, most of the existing methods only design the wind farm grouping scheme for a certain control stage after the fault of wind power generator, and the established equivalent model is difficult to accurately reflect the whole process of fault dynamics of the farm group. Therefore, it is very important to analyze the influence of low voltage ride through and crowbar control of doubly-fed wind power generator on short-circuit current during fault, and to establish an accurate wind farm model for the analysis of new power system.

[0003] Therefore, there is a need for a wind farm fault whole-process phased grouping method. SUMMARY

[0004] The present application provides a wind farm fault whole-process phased grouping method, system and electronic equipment to solve the problem of how to group the whole process of wind farm fault.

[0005] In order to solve the above problems, according to one aspect of the present application, a wind farm fault whole-process phased grouping method is provided, which comprises:

[0006] In the non-reactive stage of the converter, the whole wind farm group is grouped and equivalent based on the slip ratio and the rsc inner loop proportional coefficient of the rotor side converter;

[0007] When there is at least one wind turbine action entering Crowbar into asynchronous machine stage, the whole wind farm group is initially classified based on whether the wind turbine is in action, and then the whole wind farm group is classified and equivalent based on the slip rate and the inner loop proportional coefficient of the rotor side converter on the basis of the initial classification result;

[0008] When the Crowbar is withdrawn and all wind turbines return to the rsc control stage, the above classification result is maintained until the fault is cleared.

[0009] Preferably, wherein the whole wind farm group is classified and equivalent based on the slip rate and the rsc inner loop proportional coefficient of the rotor side converter, comprising:

[0010] According to the slip rate greater than or equal to 0 or less than 0, the whole wind farm group is classified to obtain a first wind turbine group and a second wind turbine group;

[0011] According to the rsc inner loop proportional coefficient of the rotor side converter greater than or equal to 0.5 or less than 0.5, the first wind turbine group and the second wind turbine group are classified to obtain a plurality of wind turbine subgroups;

[0012] Each wind turbine subgroup is equivalent to one wind turbine, and the equivalent parameters are calculated according to the single machine multiplication principle.

[0013] Preferably, wherein the method further comprises:

[0014] According to the wind speed and the wind turbine voltage drop amount, the Crowbar action wind turbine is identified in combination with the MPPT curve and the Crowbar action demarcation line analysis formula.

[0015] Preferably, wherein the whole wind farm group is initially classified based on whether the wind turbine is in action, and then the whole wind farm group is classified and equivalent based on the slip rate and the inner loop proportional coefficient of the rotor side converter on the basis of the initial classification result, comprising:

[0016] The whole wind farm group is divided into a wind turbine action group and a wind turbine non-action group based on whether the wind turbine is in action;

[0017] According to the slip rate greater than or equal to 0 or less than 0, the wind turbine action group is classified to obtain a plurality of wind turbine subgroups;

[0018] According to the slip rate greater than or equal to 0 or less than 0, the wind turbine non-action group is first classified, and then on the basis of the first classification result, the rsc inner loop proportional coefficient of the rotor side converter greater than or equal to 0.5 or less than 0 is used for secondary classification to obtain a plurality of wind turbine subgroups;

[0019] Each wind turbine subgroup is equivalent to one wind turbine, and the equivalent parameters are calculated according to the single machine multiplication principle.

[0020] Preferably, wherein each fan subgroup is equivalent to a fan, and the equivalent parameters are calculated according to the single machine multiplication principle, including:

[0021] For any fan subgroup, the capacity of the equivalent fan is determined according to the sum of the capacities of all fans in the any fan subgroup, the slip rate of the equivalent fan is determined according to the average of the slip rates of all fans in the any fan subgroup, and the rsc inner loop proportional coefficient of the rotor side converter of the equivalent fan is determined according to the average of the rsc inner loop proportional coefficients of the rotor side converters of all fans in the any fan subgroup;

[0022] The total current of the equivalent fan injected into the PCC of the wind farm is determined according to the sum of the currents output by all fans in the any fan subgroup;

[0023] The terminal voltage of the equivalent fan is determined according to the average of the terminal voltages of all fans in the any fan subgroup;

[0024] The connecting impedance Z between the equivalent fan and the PCC of the wind farm is calculated by the following formula eq , including:

[0025]

[0026] Wherein, U eq is the terminal voltage of the equivalent fan; U PCC is the voltage of the PCC of the wind farm; I eq is the total current of the equivalent fan injected into the PCC of the wind farm.

[0027] According to another aspect of the present application, a phased and grouped system for the whole process of wind farm fault is provided, the system comprising:

[0028] The first phase grouping unit is used to group and equivalent the whole wind farm based on the slip rate and the rsc inner loop proportional coefficient of the rotor side converter when the converter is in the non-reactive stage;

[0029] The second phase grouping unit is used to initially classify the whole wind farm based on whether the fan is in action when there is at least one fan in action entering the Crowbar input-asynchronous machine stage, and then group and equivalent the whole wind farm based on the slip rate and the inner loop proportional coefficient of the rotor side converter based on the initial classification result;

[0030] The third phase grouping unit is used to maintain the above grouping result when the Crowbar exits and all fans return to the rsc control stage until the fault is removed.

[0031] Preferably, wherein the first phase grouping unit groups and equivalents the whole wind farm based on the slip rate and the rsc inner loop proportional coefficient of the rotor side converter, including:

[0032] According to the slip greater than or equal to 0 or less than 0, the whole wind farm group is classified to obtain a first wind farm group and a second wind farm group;

[0033] According to the rsc inner loop proportional coefficient of the rotor side converter greater than or equal to 0.5 or less than 0, the first wind farm group and the second wind farm are classified to obtain a plurality of wind farm subgroups;

[0034] Each wind farm subgroup is equivalent to a wind turbine, and the equivalent parameters are calculated according to the single machine multiplication principle.

[0035] Preferably, wherein the system further comprises:

[0036] The Crowbar action wind turbine identification unit is used for identifying the Crowbar action wind turbine according to the wind speed and the wind turbine voltage drop amount, combining the MPPT curve and the Crowbar action demarcation line analysis formula.

[0037] Preferably, wherein the second stage grouping unit classifies the whole wind farm group based on whether the wind turbine is in action, and then classifies and equivalently calculates the wind turbine based on the slip and the rsc inner loop proportional coefficient of the rotor side converter, comprising:

[0038] The whole wind farm group is divided into a wind turbine action group and a wind turbine non-action group based on whether the wind turbine is in action;

[0039] The wind turbine action group is classified according to the slip greater than or equal to 0 or less than 0 to obtain a plurality of wind turbine subgroups;

[0040] The wind turbine non-action group is classified according to the slip greater than or equal to 0 or less than 0 for the first time, and then classified according to the rsc inner loop proportional coefficient of the rotor side converter greater than or equal to 0.5 or less than 0 for the second time based on the first classification result to obtain a plurality of wind turbine subgroups;

[0041] Each wind turbine subgroup is equivalent to a wind turbine, and the equivalent parameters are calculated according to the single machine multiplication principle.

[0042] Preferably, wherein the first stage grouping unit and the second stage grouping unit equivalently calculate each wind turbine subgroup to a wind turbine, and calculate the equivalent parameters according to the single machine multiplication principle, comprising:

[0043] For any wind turbine subgroup, the capacity of the equivalent wind turbine is determined according to the sum of the capacities of all wind turbines in the any wind turbine subgroup, the slip of the equivalent wind turbine is determined according to the average of the slips of all wind turbines in the any wind turbine subgroup, and the rsc inner loop proportional coefficient of the rotor side converter of the equivalent wind turbine is determined according to the average of the rsc inner loop proportional coefficients of the rotor side converters of all wind turbines in the any wind turbine subgroup.

[0044] determining the total current of the equivalent wind turbine injected into the PCC of the wind farm grid-connected point according to the sum of the currents of all wind turbines in the wind turbine sub-group;

[0045] determining the terminal voltage of the equivalent wind turbine according to the average of the terminal voltages of all wind turbines in the wind turbine sub-group;

[0046] calculating the connecting impedance Z between the equivalent wind turbine and the PCC of the wind farm grid-connected point by using the following formula eq , comprising:

[0047]

[0048] wherein, U eq is the terminal voltage of the equivalent wind turbine; U PCC is the voltage of the PCC of the wind farm grid-connected point; and I eq is the total current of the equivalent wind turbine injected into the PCC of the wind farm grid-connected point.

[0049] Based on another aspect of the present application, the present application provides a computer readable storage medium, which stores a computer program, and the program is executed by a processor to realize the steps of any one of the wind farm fault whole-process phased grouping methods.

[0050] Based on another aspect of the present application, the present application provides an electronic device, comprising:

[0051] the above computer readable storage medium; and

[0052] one or more processors for executing the program in the computer readable storage medium.

[0053] The present application provides a wind farm fault whole-process phased grouping method, system and electronic device, comprising: in the converter non-response stage, grouping and equivalent of the whole wind farm group based on the slip ratio and the rsc inner loop proportional coefficient of the rotor side converter; when there is at least one wind turbine action entering the Crowbar input-asynchronous machine stage, initial classification of the whole wind farm group based on whether the wind turbine is in action, and then grouping and equivalent of the wind farm group based on the slip ratio and the inner loop proportional coefficient of the rotor side converter based on the initial classification result; when the Crowbar exits and all wind turbines return to the rsc control stage, the above grouping result is maintained until the fault is removed. The present application can accurately depict the dynamic characteristics of the short-circuit current of the wind farm in the whole fault process, realize accurate calculation of the short-circuit current of the wind farm, and provide technical support for short-circuit calculation of high-proportion new energy power systems and equivalent grouping of wind farms. BRIEF DESCRIPTION OF DRAWINGS

[0054] The exemplary embodiments of the present application can be more completely understood by reference to the following drawings:

[0055] Figure 1 Flow chart of the phased and grouped method 100 of the whole process of wind farm fault according to the embodiment of the present application;

[0056] Figure 2 Analysis diagram of the influence of slip s on short-circuit current according to the embodiment of the present application;

[0057] Figure 3 Analysis diagram of the influence of rsc inner loop proportional coefficient on short-circuit current according to the embodiment of the present application;

[0058] Figure 4 Analysis diagram of the influence of gsc inner loop proportional coefficient on short-circuit current according to the embodiment of the present application;

[0059] Figure 5 Analysis diagram of the influence of gsc outer loop proportional coefficient on short-circuit current according to the embodiment of the present application;

[0060] Figure 6 Analysis diagram of the influence of gsc outer loop integral coefficient on short-circuit current according to the embodiment of the present application;

[0061] Figure 7 Diagram of the grouping strategy of wind farm group according to the embodiment of the present application;

[0062] Figure 8 Diagram of the whole process of grouping equivalent of wind farm group according to the embodiment of the present application;

[0063] Figure 9 Diagram of the example system of wind farm group according to the embodiment of the present application;

[0064] Figure 10 Diagram of the equivalent system model of wind farm group according to the embodiment of the present application;

[0065] Figure 11 Comparison diagram of three-phase short-circuit current of detailed model and equivalent model of example 1 according to the embodiment of the present application;

[0066] Figure 12 Comparison diagram of short-circuit current of phase A, phase B and phase C of example 1 according to the embodiment of the present application;

[0067] Figure 13 Comparison diagram of three-phase short-circuit current of detailed model and equivalent model of example 2 according to the embodiment of the present application;

[0068] Figure 14 Comparison diagram of short-circuit current of phase A, phase B and phase C of example 2 according to the embodiment of the present application;

[0069] Figure 15 A structure diagram of the wind farm fault whole-process phased-grouping system 1500 according to the embodiment of the present application. DETAILED DESCRIPTION

[0070] The present application can be implemented in many different forms and is not limited to the embodiments described herein, which are provided for the purpose of fully and completely disclosing the present application and to convey the full scope of the application to those skilled in the art. The terminology used in the description presented herein is not intended to be limiting with respect to the present application. Identical elements in the exemplary embodiments shown in the drawings are denoted by the same reference numerals.

[0071] Unless otherwise defined, the terms (including technical terms) used herein have the meanings commonly understood by one of ordinary skill in the art. In addition, it is to be understood that the terminology used herein is to be interpreted in the context of the relevant art and not in an idealized or overly formal sense.

[0072] Figure 1 A flowchart of the wind farm fault whole-process phased-grouping method 100 according to the embodiment of the present application. As shown in Figure 1 The wind farm fault whole-process phased-grouping method provided by the embodiment of the present application can accurately depict the dynamic characteristics of the wind farm short-circuit current in the whole fault process, realize accurate calculation of the wind farm short-circuit current, and provide technical support for short-circuit calculation of high-proportion new energy power systems and equivalent grouping of wind farms. The wind farm fault whole-process phased-grouping method 100 provided by the embodiment of the present application starts from step 101, in step 101, in the non-reactive stage of the converter, the entire wind farm group is grouped and equivalent based on the slip ratio and the rsc inner loop proportional coefficient of the rotor-side converter. Preferably, the grouping and equivalence of the entire wind farm group based on the slip ratio and the rsc inner loop proportional coefficient of the rotor-side converter comprises:

[0073] According to the slip ratio greater than or equal to 0 or less than 0, the entire wind farm group is classified to obtain a first wind turbine group and a second wind turbine group;

[0074] According to the rsc inner loop proportional coefficient of the rotor-side converter greater than or equal to 0.5 or less than 0.5, the first wind turbine group and the second wind turbine group are classified to obtain a plurality of wind turbine subgroups;

[0075] Each wind turbine subgroup is equivalent to a wind turbine, and the equivalent parameters are calculated according to the single-machine multiplication principle.

[0076] In step 102, when there is at least one fan action entering Crowbar input-asynchronous machine stage, the entire wind farm group is initially classified based on whether the fan is in action, and then based on the slip rate and the inner loop proportional coefficient of the rotor side converter, the group is classified and equivalent.

[0077] Preferably, wherein the method further comprises:

[0078] According to the wind speed and the fan voltage drop amount, combined with the MPPT curve and the Crowbar action demarcation line analysis formula, the identification of the Crowbar action fan is performed.

[0079] Preferably, wherein the entire wind farm group is initially classified based on whether the fan is in action, and then based on the slip rate and the inner loop proportional coefficient of the rotor side converter, the group is classified and equivalent, comprising:

[0080] The entire wind farm group is divided into a fan action group and a fan non-action group based on whether the fan is in action;

[0081] The fan action group is classified according to whether the slip rate is greater than or equal to 0 or less than 0, to obtain a plurality of fan subgroups;

[0082] The fan non-action group is first classified according to whether the slip rate is greater than or equal to 0 or less than 0, and then based on the first classification result, the rotor side converter rsc inner loop proportional coefficient is greater than or equal to 0.5 or less than 0.5 to perform secondary classification, to obtain a plurality of fan subgroups;

[0083] Each fan subgroup is equivalent to one fan, and the equivalent parameters are calculated according to the single machine multiplication principle.

[0084] Step 103, when the Crowbar exits and all fans return to the rsc control stage, the above grouping results are maintained until the fault is removed.

[0085] In the present application, the influence of fan parameter change on short-circuit current is analyzed. By finding the main factors affecting the DGIG short-circuit current, and according to these factors, all fans in the wind farm are grouped and equivalent to several fans, so that the short-circuit current characteristics of the equivalent fans are consistent with the total short-circuit current characteristics of the wind farm before equivalent, providing grouping scheme and theoretical basis for wind farm fault equivalence.

[0086] Based on PSCAD simulation platform, a typical DFIG wind turbine model is built, the transformer voltage level is 690V / 35kV, the wind turbine rated power value is 2MW, and the initial values of other main parameters affecting short-circuit current are shown in Table 1. In Table 1, rsc-d-out-p refers to the outer loop proportional coefficient of the d-axis control loop of the grid side converter (rsc), gsc-q-in-i refers to the inner loop integral coefficient of the q-axis control loop of the rotor side converter (gsc), rsc-pll-p refers to the proportional coefficient of the phase-locked loop (pll) control loop of the rsc, and the naming method of other parameters is the same. In the DFIG model, the fault type is set to AB two-phase ground short circuit, and the short-circuit point is located on the collector line, and the voltage measurement point is located at the outlet of the box transformer.

[0087] Table 1 Main parameters affecting short-circuit current

[0088] Parameter Initial value Parameter Initial value rsc-d-out-p 0.5 rsc-q-out-p 0.5 rsc-d-out-i 0.1 rsc-q-out-i 0.1 rsc-d-in-p 0.5 rsc-q-in-p 0.5 rsc-d-in-i 0.1 rsc-q-in-i 0.1 rsc-pll-p 60 rsc-pll-i 0.000 71429 gsc-d-out-p 5 gsc-d-out-i 0.004 gsc-d-in-p 0.2 gsc-q-p 0.2 gsc-d-in-i 0.1 gsc-q-i 0.1 gsc-pll-p 500 gsc-pll-i 0.000 71429 Slip s 1

[0089] In the present application, based on the exhaustive method of modifying parameters in proportion, the variation boundary of the parameters is found, that is, the extreme value that will cause control instability or almost no longer have an impact on control. A line and ratio switching method and system for self-calibration of a standard current transformer

[0090] By analyzing the influence of the 19 main parameters in Table 2 on the short-circuit current, it is found that the crowbar switching, the slip s, the proportional coefficient of the rsc inner loop, the proportional coefficient of the gsc inner loop and the proportional integral coefficient of the gsc outer loop have a more obvious influence on the short-circuit current.

[0091] The slip s affects the steady-state characteristics of the short-circuit current, and the slip can directly reflect the wind speed and distribution characteristics of the wind turbine. The slip is used as a bridge to connect the wind speed, power and short-circuit current, as shown in Figure 2 When the rsc outer loop is not cut off, the steady-state current mainly depends on the electromagnetic torque input by the outer loop, at this time the change of the slip has little effect on the steady-state current, and after the outer loop is cut off, the different slips have a more obvious influence on the short-circuit current. The slip is inversely proportional to the short-circuit current, the larger the slip, the smaller the wind speed, and the smaller the short-circuit current.

[0092] The proportional and integral coefficients of the rsc and gsc affect the transient characteristics of the short-circuit current, among which the proportional coefficient has a more obvious influence on the short-circuit current, as shown in Figure 3 and Figure 4As the proportional coefficient of rsc and gsc increases, the transient amplitude of short-circuit current presents a trend of first decreasing and then increasing. The outer loop control loop of rsc is cut off when the fault occurs, so the parameter change of the outer loop of rsc has no effect on the short-circuit current. And the transient short-circuit current oscillation frequency when the inner loop proportional coefficient of rsc is less than 0.5 is obviously different from the transient short-circuit current oscillation frequency when the inner loop proportional coefficient of rsc is greater than or equal to 0.5.

[0093] Some wind turbines will cut off the outer loop of gsc during the fault period, because if the outer loop control of gsc is retained, the reference value of the current will be increased, which is not conducive to the suppression of short-circuit current; if the outer loop of gsc is not cut off, the change of the proportional coefficient and the integral coefficient of the outer loop of gsc has a greater effect on the short-circuit current, as shown in Figure 5 and Figure 6 .

[0094] According to the above analysis of the application, among all the parameters affecting the short-circuit current, whether the Crowbar is put in or not changes the topology of the wind turbine, which has the greatest effect on the short-circuit current. Secondly, the change of the slip s changes the steady-state value of the short-circuit current, which has the greatest effect on the short-circuit current. Finally, among all the parameters affecting the transient characteristics of the short-circuit current, the inner loop proportional coefficient of rsc has the greatest effect on the transient characteristics of the short-circuit current, and other parameters have relatively small effects.

[0095] The dynamic process of DFIG after the fault can be summarized as three stages: the converter non-reaction stage, the Crowbar input-asynchronous machine stage, and the Crowbar exit-rsc control stage. The converter non-reaction stage lasts for about 2-5 ms from the fault time, then some wind turbines in the field group act the Crowbar, entering the Crowbar input-asynchronous machine stage, which lasts for 20 ms, and then the Crowbar exits, returning to the rsc control stage, entering the fault steady state, until the fault is removed. The rest of the wind turbines in the field group that do not act the Crowbar always maintain rsc control. Since the Crowbar switching changes the topology inside the wind turbine, it has a greater effect on the short-circuit current, so the grouping of the double-fed wind farm group needs to consider the dynamic similarity of DFIG in the whole fault process.

[0096] Therefore, the application adopts fault stage grouping and equivalence of wind turbines.

[0097] Wherein, in the converter unreacted stage, when all the Crowbar of the field group are not in action, only according to the slip ratio and the rsc inner loop proportional coefficient, the field group is classified and equivalent. Specifically, firstly, the field group is classified according to whether the slip ratio is greater than or equal to 0 or less than 0, and secondly, the field group is further classified according to whether the rsc inner loop proportional coefficient is greater than or equal to 0.5 or less than 0.5, so that the field group is divided into at most 4 small groups, and then each small group is equivalent to a fan, and the equivalent parameters are calculated according to the single machine multiplication principle.

[0098] After the fault occurs, according to the wind speed and the voltage drop of the fan, combined with the MPPT curve and the Crowbar action demarcation line analysis formula derived above, all the Crowbar action fans can be accurately identified without relying on the fan internal data which is difficult to obtain in real time in engineering practice, which is in line with engineering practice and has feasibility.

[0099] Wherein, when part of the fans act into the Crowbar input-asynchronous machine stage, the field group needs to be reclassified. Specifically, firstly, the field group is divided into two groups according to whether the Crowbar is in action. Secondly, for the fan group with Crowbar action, the control system inputs the Crowbar circuit and locks the rsc, thereby limiting the short-circuit current and protecting the rsc, at this time the parameter difference in the rsc has no effect on the short-circuit current, so the fan group with Crowbar action is further classified according to whether the slip ratio is greater than or equal to 0 or less than 0. For the fan group without Crowbar action, the fan maintains rsc control, so the classification strategy is consistent with the field group classification strategy in the first stage of the fault, the difference is that the number of fans is less than the number of fans in the first stage, only including the fans without Crowbar action instead of all the fans in the field group. Thus, the field group can be divided into at most 6 small groups. Finally, each small group is equivalent to a fan, and the equivalent parameters are calculated according to the single machine multiplication principle.

[0100] Wherein, in the Crowbar exit, all the fans return to the rsc control stage, since the Crowbar action has a great influence on the transient characteristics of the fan short-circuit current, the fan that has experienced Crowbar switching has a great difference in short-circuit current with the fan that has not experienced Crowbar switching after returning to the rsc control stage, and cannot be classified into a group. Therefore, the classification result of the third stage of the fault is consistent with the second stage of the fault until the fault is removed.

[0101] As Figure 7As shown, according to different fault stages and different Crowbar actions of the wind turbine, the whole wind turbines in the whole time period in the field group can be divided into six parts. For the fault characteristics presented by each part, three different grouping schemes are formulated. In the first stage of the fault, the Crowbar of all wind turbines in the whole field group is not in action, the fault characteristics have no big difference, and the whole field group is regarded as a whole for grouping, that is, the first stage of the fault in the blue part of Fig. 1. Figure 7 From the second stage of the fault, the Crowbar of part of the wind turbines is put into action, the fault characteristics of the wind turbines with Crowbar action are quite different from those of the wind turbines without Crowbar action, and the internal topology of the wind turbines is no longer consistent, so the whole field group is divided into two groups according to the Crowbar action, and the two groups are further grouped. For the group of wind turbines with Crowbar action, since the rsc is locked, the influence of the control parameters in the rsc on the short-circuit current need not be considered, and the wind turbines are only grouped according to the different slip rates, that is, the blue part of Fig. 1. Figure 7 For the group of wind turbines without Crowbar action, since the internal topology of the wind turbines is not changed, the wind turbines are still grouped according to the different slip rates and the different proportional coefficients in the rsc inner loop, but the number of wind turbines is less than that in the first stage of the fault, that is, the red part of Fig. 1. Figure 7 After entering the third stage of the fault, although the internal topology of the wind turbines in the whole field group is restored to be consistent, the short-circuit current of the wind turbines with Crowbar action is still quite different from that of the wind turbines without Crowbar action, and if the whole field group is re-grouped, the accuracy of the equivalent model will be reduced, so the grouping result in the third stage of the fault is consistent with that in the second stage of the fault.

[0102] Preferably, each wind turbine subgroup is equivalent to a wind turbine, and the equivalent parameters are calculated according to the single-machine multiplication principle, including:

[0103] For any wind turbine subgroup, the capacity of the equivalent wind turbine is determined according to the sum of the capacities of all wind turbines in the wind turbine subgroup, the slip rate of the equivalent wind turbine is determined according to the average of the slip rates of all wind turbines in the wind turbine subgroup, and the rsc inner loop proportional coefficient of the rotor side converter of the equivalent wind turbine is determined according to the average of the rsc inner loop proportional coefficients of the rotor side converters of all wind turbines in the wind turbine subgroup;

[0104] The total current of the equivalent wind turbine injected into the PCC of the wind farm is determined according to the sum of the currents output by all wind turbines in the wind turbine subgroup;

[0105] The terminal voltage of the equivalent wind turbine is determined according to the average of the terminal voltages of all wind turbines in the wind turbine subgroup;

[0106] The connecting impedance Z between the equivalent wind turbine and the PCC of the wind farm is calculated by the following formula eq , including:

[0107]

[0108] wherein, U eq is the terminal voltage of the equivalent wind turbine; U PCC is the voltage of the wind farm grid-connected point; I eq is the total current injected by the equivalent wind turbine into the wind farm grid-connected point PCC.

[0109] In the present application, each small group is equivalent to a wind turbine after the field groups are divided. Assuming that there are n wind turbines in a small group, P i , s i , k pi , v i are the capacity, the slip, the rsc inner loop proportional coefficient and the wind speed of the i-th wind turbine in the group respectively, i = 1, 2, …, n, s i of the i-th wind turbine can be obtained from v i and the MPPT curve. Assuming that the capacity, the slip, the rsc inner loop proportional coefficient and the wind speed of the corresponding equivalent wind turbine are P eq , s eq , k peq , v eq , then v eq of the equivalent wind turbine can be obtained from s eq and the MPPT curve.

[0110] The parameters of the field group network topology have an influence on the power distribution, the network loss and the terminal voltage of the wind turbines inside the wind farm, and further affect the dynamic response characteristics of the system. Therefore, the injection current conservation criterion is adopted in the present application to deduce the equivalent model parameters of the field group network topology. Assuming that there are n wind turbines in a small group, I i is the current output by the i-th wind turbine in the group, U i is the terminal voltage of the i-th wind turbine in the group, i = 1, 2, …, n, the small group is equivalent to a wind turbine. The total current injected by the small group into the wind farm grid-connected point PCC is terminal voltage of the equivalent wind turbine The voltage of the wind farm grid-connected point is U PCC , then the connecting impedance between the equivalent wind turbine and the wind farm grid-connected point is

[0111] The phase-by-phase and group-by-group equivalent process of the whole process of the wind farm fault provided by the present application is shown in Figure 8 .

[0112] In order to verify the effectiveness of the aforementioned wind farm group division method of the present application, a simulation platform is constructed as shown in Figure 9The double-fed wind farm group example system shown has a simulation step of 10 μs. The wind farm group in the example includes 15 double-fed wind turbines. Each double-fed wind turbine is connected to the grid at the wind farm grid connection point PCC after two times of voltage step-up through a 690 V / 35 kV transformer and a 35 kV / 110 kV main transformer. The fault point is located at the outlet of the wind farm grid connection point PCC, and the fault occurs at 1.5 s, and the fault type is a three-phase short-circuit fault. The system rated frequency is 50 Hz, and the line impedance is 1.5 Ω. The lengths of the 1st to 15th lines are all 20 km.

[0113] Suppose that a certain grouping divides the wind farm group into 4 small groups, and the equivalent system model of the wind farm group is shown in Figure 10 .

[0114] The difference in short-circuit current between the detailed model and the grouping equivalent model within 200 ms after the fault is compared to prove the effectiveness and accuracy of the grouping equivalent model proposed in the application. Three different example systems are formed by changing the transition resistance value of the short-circuit point, the slip of each wind turbine, and the rsc inner loop proportional coefficient to simulate the operation of the farm group under different conditions. To compare the accuracy of the grouping equivalent model, the equivalent error δ is defined as:

[0115]

[0116] In the formula, y is the short-circuit current value, y i and are the short-circuit current values of the detailed model and the grouping equivalent model at the wind farm grid connection point PCC at the sampling time i, respectively, and n is the total number of sampling points. In the example, the sampling interval is 0.00025 s, and sampling starts from the fault instant.

[0117] The smaller the equivalent error, i.e., the smaller the difference between the detailed model and the grouping equivalent model, the more accurate the grouping equivalent model

[0118] Example 1: 9 wind turbines of the 15 wind turbines are Crowbar-activated during the fault duration, and 6 wind turbines are not Crowbar-activated. The slip of the 15 wind turbines and the rsc inner loop proportional coefficient parameters, and the Crowbar action of each wind turbine at the fault occurrence are shown in Table 2.

[0119] Table 2: Wind turbine parameters in Example 1

[0120] Fan Slip rsc inner loop proportional coefficient Crowbar action condition 1 -0.2 0.125 Action 2 -0.1 0.25 Action 3 0 0.5 Action 4 0.1 1 No action 5 0.2 2 No action 6 -0.2 0.125 Action 7 -0.1 0.25 Action 8 0 0.5 Action 9 0.1 1 No action 10 0.2 2 No action 11 -0.2 0.125 Action 12 -0.1 0.25 Action 13 0 0.5 Action 14 0.1 1 No action 15 0.2 2 No action

[0121] The simulation comparison results are shown in Figure 11 and Figure 12 , Figure 11The diagram shows a comparison of the three-phase short-circuit current between the detailed model and the grouped equivalent model in Example 1. The gray dashed line represents the boundary between the first and second stages of the fault when the wind turbine Crowbar is put into operation, and the blue dashed line represents the boundary between the second and third stages of the fault when the wind turbine Crowbar is deactivated. Figure 12 The following are comparison diagrams of the short-circuit currents of phases A, B, and C in Example 1.

[0122] The equivalence error results of the cluster equivalence model in Example 1 are shown in Table 3.

[0123] Table 3 Equivalent Error in Example 1

[0124] Parameter name Equivalent error δ A-phase current 0.0215 B-phase current 0.0216 C-phase current 0.0218 Three-phase current average 0.0216

[0125] Example 2: During the fault, the Crowbars of 3 out of 15 wind turbines were engaged, while those of the remaining 12 were not. Table 4 shows the slip rate and RSC inner loop proportional coefficient parameters of the 15 wind turbines at the time of the fault, as well as the Crowbar operation status of each turbine.

[0126] Table 4. Fan parameters for Example 2

[0127]

[0128]

[0129] Simulation comparison results are as follows Figure 13 and Figure 14 As shown, Figure 13 The diagram shows a comparison of the three-phase short-circuit current between the detailed model and the grouped equivalent model in Example 2. The gray dashed line represents the boundary between the first and second stages of the fault when the wind turbine Crowbar is put into operation, and the blue dashed line represents the boundary between the second and third stages of the fault when the wind turbine Crowbar is deactivated. Figure 14 The following are comparison diagrams of the short-circuit currents of phases A, B, and C in Example 2.

[0130] In the two examples above, the three-phase short-circuit currents of the detailed model and the grouped equivalent model are almost completely consistent, with very small absolute deviations. This demonstrates the effectiveness and accuracy of the method proposed in this invention, exhibiting good equivalent accuracy. The method of this invention comprehensively considers the dynamic characteristics of the entire fault process, which also confirms the necessity of considering the dynamic characteristics of the entire fault process in grouped equivalent modeling.

[0131] The application provides a wind farm fault whole-process phased grouping method, which extracts key parameters affecting short-circuit current of a wind turbine through analysis, and further establishes a wind farm grouping method considering a fault dynamic process.

[0132] Figure 15 A structure diagram of a wind farm fault whole-process phased grouping system 1500 according to an embodiment of the application is shown in FIG. 1. Figure 15 As shown in FIG. 1, the wind farm fault whole-process phased grouping system 1500 provided by the embodiment of the application comprises a first-stage grouping unit 1501, a second-stage grouping unit 1502 and a third-stage grouping unit 1503.

[0133] Preferably, the first-stage grouping unit 1501 is configured to group and equalize the whole wind farm group based on a slip ratio and an rsc inner loop proportional coefficient of a rotor-side converter in a converter non-response stage.

[0134] Preferably, the first-stage grouping unit 1501 groups and equalizes the whole wind farm group based on the slip ratio and the rsc inner loop proportional coefficient of the rotor-side converter, and the grouping and equalization comprises:

[0135] classifying the whole wind farm group according to whether the slip ratio is greater than or equal to 0 or less than 0 to obtain a first wind turbine group and a second wind turbine group;

[0136] classifying the first wind turbine group and the second wind turbine group according to whether the rsc inner loop proportional coefficient of the rotor-side converter is greater than or equal to 0.5 or less than 0.5 to obtain a plurality of wind turbine subgroups;

[0137] equalizing each wind turbine subgroup to one wind turbine, and calculating equivalent parameters according to a single-machine multiplication principle.

[0138] Preferably, the second-stage grouping unit 1502 is configured to initially classify the whole wind farm group based on whether a wind turbine is in action when at least one wind turbine is in action and enters a Crowbar input-asynchronous machine stage, and then group and equalize the whole wind farm group based on the slip ratio and the inner loop proportional coefficient of the rotor-side converter on the basis of the initial classification result.

[0139] Preferably, the system further comprises:

[0140] The crowbar action wind turbine identification unit is used to identify the wind turbine with crowbar action according to the wind speed and the wind turbine voltage drop amount, in combination with the MPPT curve and the crowbar action demarcation line analysis formula.

[0141] Preferably, the second-stage grouping unit 1502 performs initial classification on the entire wind farm group based on whether the wind turbine is in action, and then performs grouping equivalence based on the slip rate and the inner loop proportional coefficient of the rotor-side converter on the basis of the initial classification result, including:

[0142] The entire wind farm group is divided into a wind turbine action group and a wind turbine non-action group based on whether the wind turbine is in action;

[0143] The wind turbine action group is classified according to whether the slip rate is greater than or equal to 0 or less than 0, to obtain a plurality of wind turbine subgroups;

[0144] The wind turbine non-action group is classified for the first time according to whether the slip rate is greater than or equal to 0 or less than 0, and then classified for the second time according to whether the rsc inner loop proportional coefficient of the rotor-side converter is greater than or equal to 0.5 or less than 0.5 on the basis of the first classification result, to obtain a plurality of wind turbine subgroups;

[0145] Each wind turbine subgroup is equivalent to a wind turbine, and the equivalent parameters are calculated according to the single-machine multiplication principle.

[0146] Preferably, the first-stage grouping unit 1501 and the second-stage grouping unit 1502 each wind turbine subgroup is equivalent to a wind turbine, and the equivalent parameters are calculated according to the single-machine multiplication principle, including:

[0147] For any wind turbine subgroup, the capacity of the equivalent wind turbine is determined according to the sum of the capacities of all wind turbines in the any wind turbine subgroup, the slip rate of the equivalent wind turbine is determined according to the average of the slip rates of all wind turbines in the any wind turbine subgroup, and the rsc inner loop proportional coefficient of the rotor-side converter of the equivalent wind turbine is determined according to the average of the rsc inner loop proportional coefficients of the rotor-side converters of all wind turbines in the any wind turbine subgroup;

[0148] The total current of the equivalent wind turbine injected into the PCC of the wind farm is determined according to the sum of the currents output by all wind turbines in the any wind turbine subgroup;

[0149] The terminal voltage of the equivalent wind turbine is determined according to the average of the terminal voltages of all wind turbines in the any wind turbine subgroup;

[0150] The connecting impedance Z between the equivalent wind turbine and the PCC of the wind farm is calculated by the following formula eq , including:

[0151]

[0152] wherein, U eq is the terminal voltage of the equivalent wind turbine; U PCC is the voltage at the point of common coupling (PCC) of the wind farm; I eq is the total current injected by the equivalent wind turbine into the PCC of the wind farm.

[0153] Preferably, the third stage grouping unit 1503 is configured to maintain the above grouping result when all wind turbines return to the rsc control stage after the Crowbar is withdrawn, until the fault is cleared.

[0154] The wind farm fault whole-process phased grouping system 1500 of the embodiment of the present application corresponds to the wind farm fault whole-process phased grouping method 100 of another embodiment of the present application, which will not be described here again.

[0155] Based on another aspect of the present application, the present application provides a computer readable storage medium, which stores a computer program, the program being executed by a processor to implement the steps of any one of the wind farm fault whole-process phased grouping methods.

[0156] Based on another aspect of the present application, the present application provides an electronic device, comprising:

[0157] the above computer readable storage medium; and

[0158] one or more processors configured to execute the program in the computer readable storage medium.

[0159] The present application has been described with reference to a few embodiments. However, other embodiments known to those of ordinary skill in the art, which are within the scope of the present application, are equally foreseeable.

[0160] Generally, all terms used in the present application are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a" or "an" means "at least one" unless otherwise clearly indicated by the context of the only language "the". The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

[0161] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, systems, or computer program products. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage media, etc.) embodying computer usable program code.

[0162] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0163] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0164] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0165] Finally, it should be noted that the above-mentioned embodiments are merely used to illustrate the technical solutions of the present application, but are not intended to limit the present application. Although the present application has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced, and any modification or replacement without departing from the spirit and scope of the present application should be covered within the protection scope of the present application.

Claims

1. A phased clustering method for the entire fault process of a wind farm, characterized in that, The method includes: During the unresponsive phase of the converter, the entire wind farm group is grouped and equalized based on the slip rate and the RSC inner loop proportional coefficient of the rotor-side converter. When at least one wind turbine operates and enters the crowbar-asynchronous machine phase, the entire wind farm group is initially classified based on whether the wind turbine operates. Then, based on the initial classification results, the group is further subdivided and valued according to the slip ratio and the inner loop proportional coefficient of the rotor-side converter. When Crowbar exits and all fans return to the RSC control phase, the above grouping results are maintained until the fault is cleared.

2. The method according to claim 1, characterized in that, The entire wind farm group is grouped and equalized based on slip ratio and the RSC inner loop proportional coefficient of the rotor-side converter, including: The entire wind turbine cluster is classified according to whether the slip ratio is greater than or equal to 0 or less than 0, thus obtaining the first wind turbine group and the second wind turbine group. The first and second wind turbine groups are classified according to whether the RSC inner loop proportional coefficient of the rotor-side converter is greater than or equal to 0.5 or less than 0.5, so as to obtain multiple wind turbine subgroups. Each wind turbine subgroup is treated as a single wind turbine, and the equivalent parameters are calculated according to the single-machine multiplication principle.

3. The method according to claim 1, characterized in that, The method further includes: Based on wind speed and fan voltage drop, combined with MPPT curves and the analytical formula for Crowbar action boundary line, the fan with Crowbar action is identified.

4. The method according to claim 1, characterized in that, The entire wind farm group is initially classified based on whether the wind turbines are operating. Then, based on the initial classification results, further grouping and equivalence are performed based on slip rate and the inner loop proportional coefficient of the rotor-side converter, including: Based on whether the wind turbines are operating, the entire wind farm group is divided into a wind turbine operating group and a wind turbine non-operating group. The wind turbine action groups are classified according to whether the forwarding rate is greater than or equal to 0 or less than 0, so as to obtain multiple wind turbine subgroups; The non-operational wind turbine groups are first classified according to whether the slip ratio is greater than or equal to 0 or less than 0. Then, based on the results of the first classification, a second classification is performed according to whether the RSC inner loop proportional coefficient of the rotor-side converter is greater than or equal to 0.5 or less than 0.5, so as to obtain multiple wind turbine subgroups. Each wind turbine subgroup is treated as a single wind turbine, and the equivalent parameters are calculated according to the single-machine multiplication principle.

5. The method according to claim 2 or 4, characterized in that, Each wind turbine subgroup is equivalent to one wind turbine, and the equivalent parameters are calculated according to the single-unit multiplication principle, including: For any wind turbine subgroup, the capacity of the equivalent wind turbine is determined by the sum of the capacities of all wind turbines in the subgroup, the slip of the equivalent wind turbine is determined by the average slip of all wind turbines in the subgroup, and the RSC inner loop proportional coefficient of the rotor-side converter of the equivalent wind turbine is determined by the average RSC inner loop proportional coefficient of the rotor-side converter of all wind turbines in the subgroup. The total current injected into the grid connection point PCC of the wind farm by the equivalent wind turbine is determined by the sum of the current output of all wind turbines in any wind turbine subgroup. The terminal voltage of the equivalent fan is determined based on the average terminal voltage of all fans within any given fan subgroup. The connection impedance Z between the equivalent wind turbine and the grid connection point of the wind farm is calculated using the following formula. eq ,include: Among them, U eq U is the equivalent terminal voltage of the blower; PCC I is the voltage at the grid connection point of the wind farm. eq The total current injected into the PCC at the grid connection point of the wind farm for the equivalent wind turbine.

6. A phased clustering system for the entire fault process of a wind farm, characterized in that, The system includes: The first-stage grouping unit is used to group the entire wind farm group equally based on the slip rate and the RSC inner loop proportional coefficient of the rotor-side converter during the unresponsive phase of the converter. The second-stage grouping unit is used to perform an initial classification of the entire wind farm group based on whether the wind turbine is in operation when at least one wind turbine is activated and enters the crowbar-asynchronous machine stage. Then, based on the initial classification results, grouping is performed based on the slip rate and the inner loop proportional coefficient of the rotor-side converter. The third-stage grouping unit is used to maintain the above grouping results when Crowbar exits and all fans return to the RSC control stage, until the fault is cleared.

7. The system according to claim 6, characterized in that, The first-stage grouping unit, based on the slip rate and the RSC inner loop proportional coefficient of the rotor-side converter, performs grouping and equalization of the entire wind farm group, including: The entire wind turbine cluster is classified according to whether the slip ratio is greater than or equal to 0 or less than 0, thus obtaining the first wind turbine group and the second wind turbine group. The first and second wind turbine groups are classified according to whether the RSC inner loop proportional coefficient of the rotor-side converter is greater than or equal to 0.5 or less than 0.5, so as to obtain multiple wind turbine subgroups. Each wind turbine subgroup is treated as a single wind turbine, and the equivalent parameters are calculated according to the single-machine multiplication principle.

8. The system according to claim 6, characterized in that, The system also includes: The Crowbar Action Fan Identification Unit is used to identify fans exhibiting Crowbar Action based on wind speed and fan voltage drop, combined with MPPT curves and Crowbar Action Boundary Line analytical formulas.

9. The system according to claim 6, characterized in that, The second-stage grouping unit performs an initial classification of the entire wind farm group based on whether the wind turbines are operating. Then, based on the initial classification results, it performs grouping equivalence based on slip and the inner loop proportional coefficient of the rotor-side converter, including: Based on whether the wind turbines are operating, the entire wind farm group is divided into a wind turbine operating group and a wind turbine non-operating group. The wind turbine action groups are classified according to whether the forwarding rate is greater than or equal to 0 or less than 0, so as to obtain multiple wind turbine subgroups; The non-operational wind turbine groups are first classified according to whether the slip ratio is greater than or equal to 0 or less than 0. Then, based on the results of the first classification, a second classification is performed according to whether the RSC inner loop proportional coefficient of the rotor-side converter is greater than or equal to 0.5 or less than 0.5, so as to obtain multiple wind turbine subgroups. Each wind turbine subgroup is treated as a single wind turbine, and the equivalent parameters are calculated according to the single-machine multiplication principle.

10. The system according to claim 7 or 9, characterized in that, The first-stage clustering unit and the second-stage clustering unit treat each wind turbine subgroup as equivalent to one wind turbine, and calculate the equivalent parameters according to the single-machine multiplication principle, including: For any wind turbine subgroup, the capacity of the equivalent wind turbine is determined by the sum of the capacities of all wind turbines in the subgroup, the slip of the equivalent wind turbine is determined by the average slip of all wind turbines in the subgroup, and the RSC inner loop proportional coefficient of the rotor-side converter of the equivalent wind turbine is determined by the average RSC inner loop proportional coefficient of the rotor-side converter of all wind turbines in the subgroup. The total current injected into the grid connection point PCC of the wind farm by the equivalent wind turbine is determined by the sum of the current output of all wind turbines in any wind turbine subgroup. The terminal voltage of the equivalent fan is determined based on the average terminal voltage of all fans within any given fan subgroup. The connection impedance Z between the equivalent wind turbine and the grid connection point of the wind farm is calculated using the following formula. eq ,include: Among them, U eq U is the equivalent terminal voltage of the blower; PCC I is the voltage at the grid connection point of the wind farm. eq The total current injected into the PCC at the grid connection point of the wind farm for the equivalent wind turbine.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 1-5.

12. An electronic device, characterized in that, include: The computer-readable storage medium as described in claim 11; as well as One or more processors for executing a program in the computer-readable storage medium.

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