Equivalent modeling method and system suitable for safe and stable operation of new energy stations

Abstract

The present application relates to an equivalent modeling method and system suitable for the safe and stable operation of a new energy station, including: obtaining the original topological structure of the target new energy station, the information of each unit and the station collector line information; establishing the road matrix and impedance matrix of the station collector line; converting the original topological structure into a radial topological structure to obtain the equivalent impedance of the converter collector line of each unit; obtaining fault-related information when a fault occurs in the new energy station, and calculating the terminal voltage vector of each unit after the fault; dividing all units into X clusters; obtaining the voltage on the low-voltage side of the main transformer of the target new energy station, and performing equivalent calculations on the X clusters respectively to obtain the equivalent model of the detailed model of the target new energy station. The equivalent method of the present application can fit the dynamic characteristics of the detailed model of the new energy station when the station is in steady state, fault, and fault recovery, which is conducive to ensuring the safe and stable operation of the new energy station.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to an equivalent modeling method and system suitable for the safe and stable operation of new energy stations. Background Art

[0002] At present, the research on equivalent modeling of new energy stations focuses on three aspects: unit classification index, grouping method and equivalent parameter calculation. In terms of classification index selection, the voltage results of power flow calculation, voltage during fault, power and other electrical quantities can be used as characteristic information. For wind turbines, the Crowbar and Chopper protection action states during faults can also be considered as the basis for grouping. In terms of grouping methods, K-means and its improved algorithms are widely used because of their simple principles. Other clustering algorithms such as fuzzy C-means and its improved algorithms and neural network-based clustering algorithms are also applied to the equivalent calculation of new energy stations.

[0003] The existing method for calculating the equivalent value of the detailed model of the new energy station is to collect the voltage, power and other indicators during the fault period of the detailed model; use kmeans and other methods to group; calculate the equivalent parameters after grouping, among which the calculation method of the equivalent parameters of the collector line can be divided into weighted voltage difference and equal loss method; form an equivalent model;

[0004] Problems with existing methods: 1. The current calculation method of equivalent parameters of collector lines is complex, resulting in limitations in calculating equivalent parameters of different topologies. 2. The unit status (whether the unit enters low voltage ride-through) is not considered during the grouping process, and the equivalent results are inaccurate. 3. It is necessary to obtain the electrical quantity information of the detailed model of the new energy station during the fault period, which is not suitable for the equivalent of new energy stations in large power grids. Summary of the invention

[0005] In response to the above problems, the present application provides an equivalent modeling method and system suitable for the safe and stable operation of new energy stations, which solves the technical problems in related technologies such as complex calculation methods, grouping without considering the unit status, resulting in inaccurate equivalent results and limited scope of application.

[0006] In a first aspect, the present application provides an equivalent modeling method applicable to the safe and stable operation of a new energy station, the method comprising:

[0007] Obtain the original topological structure of the target new energy station, information about each unit, and information about the station's power collection lines;

[0008] According to the original topological structure, the information of each unit and the information of the station collection line, a road matrix T and an impedance matrix Z of the station collection line are established;

[0009] According to the information of each unit and the station collector line information, as well as the road matrix T and the impedance matrix Z, the original topology is converted into a radial topology to obtain the equivalent impedance Z of the converter collector line of each unit. b ;

[0010] When a fault occurs at the new energy station, fault-related information is obtained, and a terminal voltage vector U of each unit after the fault is calculated based on the fault-related information, the road matrix T and the impedance matrix Z;

[0011] Clustering all the units according to the terminal voltage vector U of each unit after the fault and the information of each unit, and dividing all the units into X cluster groups;

[0012] Obtain the low-voltage side voltage of the main transformer of the target new energy station, and calculate the equivalent impedance Z of the converter collector line of each unit according to the impedance Z of the converter collector line of each unit. b and the information of each unit, respectively perform equivalent operations on the X cluster groups to obtain an equivalent model of the target new energy site detailed model.

[0013] In some embodiments, the crew information includes:

[0014] The output current of the converter in the unit, the low voltage side voltage of the transformer, the transformer impedance, the transformer capacity and the active power of the unit. Each unit includes a converter and a transformer connected to the converter.

[0015] In some embodiments, the station collection line information includes:

[0016] Station collection line model, line resistance, and line reactance.

[0017] In some embodiments, the original topology structure includes:

[0018] The target new energy station includes n units, which are connected by collector lines, and there are m line collection points in the collector lines. The low-voltage side of the main transformer of the target new energy station is the root node R, and the original topological structure of the typical tree structure is formed starting from the root node R.

[0019] In some embodiments, clustering all the units according to the terminal voltage vector U of each unit after the fault and the information of each unit, and dividing all the units into X cluster groups, includes:

[0020] According to the terminal voltage vector U of each unit after the fault, whether each unit enters the low voltage ride-through state is determined to obtain a determination result;

[0021] If the judgment result indicates that all units have entered the low voltage ride-through state, the units are divided into two clusters of high power low voltage and low power high voltage according to the unit active power of each unit and the terminal voltage vector U of each unit after the fault;

[0022] If the judgment result indicates that not all units have entered the low voltage ride-through state, all units are divided into two groups according to whether they have entered the low voltage ride-through, and the group of units entering the low voltage ride-through is grouped again according to the preset ratio threshold and the active power of the units, and finally X cluster groups are obtained.

[0023] In a second aspect, an equivalent modeling system suitable for safe and stable operation of a new energy station is provided, the system comprising:

[0024] An acquisition unit is used to acquire the original topological structure of the target new energy station, information of each unit and station collection line information;

[0025] An establishing unit, used for establishing a road matrix T and an impedance matrix Z of a station collector line according to the original topological structure, the information of each unit and the station collector line information;

[0026] A conversion unit is used to convert the original topology into a radial topology according to the information of each unit and the station collector line information, the road matrix T and the impedance matrix Z, and obtain the equivalent impedance Z of the converter collector line of each unit. b ;

[0027] A calculation unit, used for obtaining fault-related information when a fault occurs in a new energy station, and calculating a terminal voltage vector U of each unit after the fault according to the fault-related information, the road matrix T and the impedance matrix Z;

[0028] A clustering unit, used for clustering all the units according to the terminal voltage vector U of each unit after the fault and the information of each unit, and dividing all the units into X cluster groups;

[0029] The equivalent unit is used to obtain the low-voltage side voltage of the main transformer of the target new energy station, and according to the equivalent impedance Z of the converter collector line of each unit b and the information of each unit, respectively perform equivalent operations on the X cluster groups to obtain an equivalent model of the target new energy site detailed model.

[0030] In some embodiments, the crew information includes:

[0031] The output current of the converter in the unit, the low voltage side voltage of the transformer, the transformer impedance, the transformer capacity and the active power of the unit. Each unit includes a converter and a transformer connected to the converter.

[0032] In some embodiments, the station collection line information includes:

[0033] Station collection line model, line resistance, and line reactance.

[0034] In some embodiments, the original topology structure includes:

[0035] The target new energy station includes n units, which are connected by collector lines, and there are m line collection points in the collector lines. The low-voltage side of the main transformer of the target new energy station is the root node R, and the original topological structure of the typical tree structure is formed starting from the root node R.

[0036] In some embodiments, the clustering unit is used to determine whether each unit enters a low voltage ride-through state according to the terminal voltage vector U of each unit after the fault, and obtain a judgment result; if the judgment result indicates that all units enter a low voltage ride-through state, then the units are divided into two clustering groups of high power low voltage and low power high voltage according to the unit active power of each unit and the terminal voltage vector U of each unit after the fault; if the judgment result indicates that not all units enter a low voltage ride-through state, then all units are divided into two groups according to whether they enter a low voltage ride-through, and the group to which the units entering the low voltage ride-through belong is grouped again according to a preset ratio threshold and the unit active power, and finally X clustering groups are obtained.

[0037] The present application provides an equivalent modeling method and system suitable for safe and stable operation of a new energy station, including: obtaining the original topological structure of the target new energy station, information of each unit and information of the station collector line; establishing a road matrix T and an impedance matrix Z of the station collector line according to the original topological structure, the information of each unit and the station collector line information; according to the information of each unit and the station collector line information, as well as the road matrix T and the impedance matrix Z, converting the original topological structure into a radial topological structure, and obtaining the equivalent impedance Z of the converter collector line of each unit b ; When a fault occurs in a new energy station, obtain fault-related information, and calculate the terminal voltage vector U of each unit after the fault according to the fault-related information, the road matrix T and the impedance matrix Z; cluster all units according to the terminal voltage vector U of each unit after the fault and the information of each unit, and divide all units into X cluster groups; obtain the low-voltage side voltage of the main transformer of the target new energy station, and according to the equivalent impedance Z of the converter collector line of each unit band the information of each unit, respectively perform equivalence on the X cluster groups to obtain an equivalence model of the target new energy station detailed model. The equivalence method of the present application can fit the dynamic characteristics of the new energy station detailed model when the station is in steady state, fault, and fault recovery, which is conducive to ensuring the safe and stable operation of the new energy station. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0039] Figure 1 A flow chart of an equivalent modeling method applicable to the safe and stable operation of a new energy station provided in an embodiment of the present application;

[0040] Figure 2 A schematic diagram of the network topology structure of a new energy station before and after conversion provided in an embodiment of the present application;

[0041] Figure 3 A schematic diagram of the structure of a new energy delivery system provided in an embodiment of the present application;

[0042] Figure 4 A schematic diagram of the original topological structure of a new energy station provided in another embodiment of the present application;

[0043] Figure 5 A schematic diagram of detailed model voltage distribution during steady state and fault period of a new energy station provided by another embodiment of the present application;

[0044] Figure 6 A schematic diagram of comparing the status of units during a failure of a new energy station provided by another embodiment of the present application;

[0045] Figure 7a A comparison diagram of 35kV bus voltage equivalents for a new energy station provided in another embodiment of the present application;

[0046] Figure 7b A comparison diagram of the output active power equivalents of a new energy station provided in another embodiment of the present application;

[0047] Figure 7c A comparison diagram of reactive power output equivalents of a new energy station provided in another embodiment of the present application;

[0048] Figure 8 A structural schematic diagram of an equivalent modeling system suitable for safe and stable operation of new energy stations provided in an embodiment of the present application. DETAILED DESCRIPTION

[0049] The following will describe the implementation methods of the present application in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present application applies technical means to solve technical problems and achieve corresponding technical effects can be fully understood and implemented accordingly. The embodiments of the present application and the various features in the embodiments can be combined with each other without conflict, and the technical solutions formed are all within the scope of protection of the present application.

[0050] Embodiment 1

[0051] Figure 1 A flow chart of an equivalent modeling method for the safe and stable operation of a new energy station provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the method includes:

[0052] S101, obtaining the original topological structure of the target new energy station, information of each unit and information of the station collection line;

[0053] In some embodiments, the crew information includes:

[0054] The output current of the converter in the unit, the low voltage side voltage of the transformer, the transformer impedance, the transformer capacity and the active power of the unit. Each unit includes a converter and a transformer connected to the converter.

[0055] In some embodiments, the station collection line information includes:

[0056] Station collection line model, line resistance, and line reactance.

[0057] In some embodiments, the original topology structure includes:

[0058] The target new energy station includes n units, which are connected by collector lines, and there are m line collection points in the collector lines. The low-voltage side of the main transformer of the target new energy station is the root node R, and the original topological structure of the typical tree structure is formed starting from the root node R.

[0059] S102, establishing a road matrix T and an impedance matrix Z of a station collector line according to the original topological structure, the information of each unit and the station collector line information;

[0060] It can be seen from the content of step S101 that the new energy station has n converters, and the corresponding nodes are N1, N2...Nn, and each converter is connected to a 35kV box-type step-up transformer. There are m line collection points in the collector line, and the corresponding nodes are Nn+1, Nn+2...Nn+m. The low-voltage side of the 330kV main transformer of the station is node R. Since there is no ring network in the collector line of the new energy station, it is a typical tree structure, in which the root node is R, and the direction of each branch pointing to the root node is stipulated to be the positive direction, and the branch number is consistent with its starting point number. The node Ni is used as the starting point, and the branch number pointing to R is bi. The road of a node refers to the set of branches on the path from the node along the tree to the root. Therefore, for a collector line network, a unique road matrix T can be obtained, and it is a square matrix with a dimension of n+m. The element tik in the i-th row and the k-th column of the T matrix is:

[0061]

[0062] From this, we can get the collector line road matrix T:

[0063]

[0064] Assume the impedance of the kth branch is zk, and the impedances of the m+n branches in the station form a matrix Z, that is,

[0065]

[0066] In engineering applications, the station collector line layout information can be completely stored in the road matrix T and the impedance matrix Z, which is convenient for subsequent equivalent calculations.

[0067] S103, according to the information of each unit and the station collector line information, as well as the road matrix T and the impedance matrix Z, the original topology structure is converted into a radial topology structure to obtain the equivalent impedance Z of the converter collector line of each unit b ;

[0068] It should be noted that the topology transformation of the collector line is the basis of equivalent calculation. First, the complex original topology of the station is transformed into a radial topology, and then the equivalent impedance of each converter is obtained. Then, the subsequent unit clustering and equivalent machine impedance calculation are performed. The topology transformation process follows the principle of unchanged line loss. Figure 2 The figure shows the schematic diagram of the network topology structure of new energy stations before and after the conversion.

[0069] It should be further explained that the equivalent value machine is to cluster the existing units and then equate the units in the same cluster group to all the same equivalent value machines.

[0070] Specifically, when the original topology is converted to the radial topology, assuming that the output currents I1, I2, ...Ih of h converters flow through branch k, the equivalent impedance of branch k is:

[0071]

[0072] Since there is no injected power from node Nn+1 to node Nn+m, there is no need to calculate its equivalent impedance in the equivalent calculation. Therefore, the first n rows in the T matrix are taken as the equivalent road matrix TG, and the station current vector is:

[0073]

[0074] The current flowing through each branch is:

[0075]

[0076] The square of the current flowing through each branch, that is, the numerator expression of the equivalent impedance is:

[0077]

[0078] In the formula, Indicates the Hadamard product of the calculation matrix. The sum of the squares of the current flowing through each branch, that is, the denominator of the equivalent impedance expression is:

[0079]

[0080] From this, the equivalent impedance matrix expression of the kth branch in the network can be obtained as follows:

[0081]

[0082] The equivalent impedance vector is obtained as follows:

[0083]

[0084] The equivalent impedance Zbi of the collector line of the i-th converter is the sum of the equivalent impedances Zeqx of all branches on the converter line, where x is the specific number of branches of all branches. The equivalent impedance of the collector line of each converter is:

[0085]

[0086] Based on the road matrix, the equivalent impedance vector can be obtained:

[0087]

[0088] in,

[0089]

[0090] In this way, the equivalent impedance of the collector line of each converter in the new energy station can be obtained, and the complex original topology of the collector line is converted into a radial topology, which serves as the basis for subsequent equivalent calculations.

[0091] S104, when a fault occurs at the new energy station, obtaining fault-related information, and calculating the terminal voltage vector U of each unit after the fault according to the fault-related information, the road matrix T and the impedance matrix Z;

[0092] It should be noted that when a new energy station fails, the relationship between the fault node and the equivalent node of the external power grid is considered on the basis of the road matrix. Specifically, Figure 3 The figure shows the schematic diagram of the structure of the new energy transmission system.

[0093] Depend on Figure 3 It can be seen that on the basis of the new energy station road matrix, by adding the columns corresponding to zw, zs1, and zs2, and the rows corresponding to R, W, and F, the delivery system road matrix can be obtained:

[0094]

[0095] The node impedance matrix of the sending-end system containing the new energy station can be expressed by the road matrix and the branch impedance matrix:

[0096]

[0097] After the fault occurs, the terminal voltage of the i-th unit in the new energy station can be expressed as:

[0098]

[0099] In the formula, is the transformer low-voltage side voltage of the new energy unit i before the fault occurs, is the voltage generated by the fault current acting on node i alone, and Zif is the mutual impedance between nodes i and F in the node impedance matrix. The fault point f must meet the fault boundary conditions:

[0100]

[0101] In the formula, , are the voltage at the fault point f before and after the fault occurs, Z ff is the self-impedance of the fault node F in the node impedance matrix, z f Including the transition resistance and the asymmetric short-circuit additional impedance based on the positive sequence equivalent rule, the low-voltage side voltage of the transformer of the i-th new energy unit after the fault occurs is:

[0102]

[0103] Since for a network without a connecting branch, the self-impedance of point F is zs2, and the mutual impedance between node i of the new energy unit and node F is zs2, the voltage fault component is the same for different new energy units.

[0104] Considering that the transformation ratio of the i-th transformer is tki, the terminal voltage vector of the new energy unit after the fault can be calculated based on the steady-state voltage distribution of each unit in the station:

[0105]

[0106] Furthermore, U can be used to determine whether the new energy generating units in the station have entered the low voltage ride-through state.

[0107] S105, clustering all the units according to the terminal voltage vector U of each unit after the fault and the information of each unit, and dividing all the units into X cluster groups;

[0108] In some embodiments, clustering all the units according to the terminal voltage vector U of each unit after the fault and the information of each unit, and dividing all the units into X cluster groups, includes:

[0109] According to the terminal voltage vector U of each unit after the fault, whether each unit enters the low voltage ride-through state is determined to obtain a determination result;

[0110] If the judgment result indicates that all units have entered the low voltage ride-through state, the units are divided into two clusters of high power low voltage and low power high voltage according to the unit active power of each unit and the terminal voltage vector U of each unit after the fault;

[0111] If the judgment result indicates that not all units have entered the low voltage ride-through state, all units are divided into two groups according to whether they have entered the low voltage ride-through, and the group of units entering the low voltage ride-through is grouped again according to the preset ratio threshold and the active power of the units, and finally X cluster groups are obtained.

[0112] It should be noted that the Kmeans algorithm can be used to cluster all new energy units.

[0113] Specifically, whether the unit enters low voltage ride through can be determined by judging whether the terminal voltage vector U of each unit is less than 0.9 unit terminal voltage per unit value (i.e. 0.9pu). If all units enter low voltage ride through, the station is divided into four groups according to the voltage and power distribution. If the equivalent model is further simplified, it can be divided into two groups: high power low voltage and low power high voltage.

[0114] If not all units enter low-voltage penetration, they will first be divided into two groups based on whether they have entered low-voltage penetration. For the units that have entered the low-voltage penetration group, if the proportion of their units in the station units reaches 50%, they will be divided into two groups based on active power, that is, the station as a whole will be divided into three groups. If the proportion reaches 75%, they will be divided into three groups based on active power, that is, the station as a whole will be divided into four groups.

[0115] The preset ratio thresholds are the two thresholds where the ratio of units to station units reaches 50% and 75%.

[0116] During the clustering process, since the method proposed in this application does not require electromechanical transient simulation of the detailed station model to obtain a lot of information, the data set only contains unit voltage and active power. Therefore, after the two types of data are normalized, the K-means algorithm is used for clustering. This can meet the calculation requirements while making the present application have better engineering practicality than existing methods.

[0117] S106, obtaining the low voltage side voltage of the main transformer of the target new energy station, and according to the equivalent impedance Z of the converter collector line of each unit b and the information of each unit, respectively perform equivalent operations on the X cluster groups to obtain an equivalent model of the target new energy site detailed model.

[0118] It should be noted that the detailed model refers to the actual model of the new energy station, including various parameters of the actual unit.

[0119] It should be noted that since each converter is the same and the connected transformer is also the same, considering that all transformers in the new energy station are of the same model and have equal impedance, the single-machine multiplication method is used for equalization. The transformer impedance of the j-th equivalent machine is:

[0120]

[0121] In the formula, ZT is the transformer impedance before the unit is equivalent, and N is the number of converters in the cluster where the equivalent machine is located. The equivalent transformer capacity is:

[0122]

[0123] ST is the transformer capacity before the unit is equalized. For the jth equivalent unit, assuming there are N converters in the group, the equivalent impedance of the jth equivalent unit is:

[0124]

[0125] In the formula, zi=Zbi is the equivalent impedance of the collector line of the i-th converter, and Ii is the output current of the i-th converter. The j-th equivalent power is:

[0126]

[0127] Among them, it is generally believed that voltage is 1, so power can be replaced by I instead of P.

[0128] It should be further explained that, for the equivalent value of the collector line, in order to make the equivalent value machine reflect the voltage drop situation of the station, the collector line parameters can be calculated according to the average steady-state machine terminal voltage in the machine group, which is the equal voltage drop method.

[0129] Specifically, obtain the low-voltage side voltage of the main transformer of the new energy station , for the N units in the cluster where the j-th equivalent unit is located, assuming that the steady-state terminal voltage of the equivalent unit is the average terminal voltage of the N units, then the steady-state terminal voltage of the j-th equivalent unit is:

[0130]

[0131] In the formula is the terminal voltage of the N units in the cluster where the jth equivalent unit is located, and the total equivalent impedance of the collector line and the equivalent transformer is calculated as

[0132]

[0133] In the formula, is the low-voltage side voltage of the main transformer of the new energy station, and then the equivalent impedance of the collector line is obtained:

[0134]

[0135] Where ZT is the transformer impedance before the unit is equalized.

[0136] At the same time, in order to make the total output power of the new energy station consistent, the comparative equal loss method is used to compensate the power of the equivalent value machine. For the jth equivalent value machine, assuming that there are N converters in the group where it belongs, its equal loss impedance can be calculated using the equivalent impedance formula:

[0137]

[0138] Where, zi=Zbi is the equivalent impedance of the collector line of the i-th converter, and Ii is the output current of the i-th converter.

[0139] The difference in total loss of equal value machine j on the collector circuit is calculated using the equal voltage drop method and the equal loss method. In the per-unit value system, we have:

[0140]

[0141] Where: ∆S is the power to be compensated for the equivalent machine. It can be obtained that after compensating for line loss, the output current of the equivalent machine j is:

[0142]

[0143] Therefore, by combining the above content, we can get the power Idj, collector line impedance Zdzj, equivalent machine transformer impedance ZTj, and equivalent machine transformer capacity STj of the equivalent machine. Then, we can obtain the transformer reactance and collector line reactance through calculation, complete the equivalent machine parameters, and complete the equivalent model.

[0144] In order to facilitate understanding of the technical solution of this application, the following examples are given for illustration:

[0145] Taking a photovoltaic power station in Shaanxi Province as an example, a detailed model is built in PSASP, and the equivalent modeling is performed using the method proposed in this paper. The terminal voltage of the photovoltaic power station is 35kV, the rated installed capacity is 100MW, there are 32 unit transformers in the station, each unit transformer is equivalent to a power generation unit, its rated capacity is 3.3MW, there are four types of collector line conductors, and the impedance values ​​are shown in Table 1.

[0146] Table 1

[0147]

[0148] The schematic diagram of the original topological structure of the new energy station in this embodiment is as follows: Figure 4 As shown, 32 unit transformers are connected to the 35kV busbars at both ends through collector lines, and then collected to the grid connection point, and then stepped up to 220kV through the main transformer to be connected to the grid.

[0149] Assume that the first branch number on the road from each node to the root node (grid connection point) is consistent with the node number, and the branch line models and impedances of the new energy station are shown in Table 2.

[0150] Table 2

[0151] Branch Road model Resistance (pu) Reactance (pu) Branch Road model Resistance (pu) Reactance (pu) b1 1 0.0094 0.0059 b18 1 0.0094 0.0059 b2 1 0.0122 0.0077 b19 2 0.0074 0.0057 b3 1 0.0104 0.0066 b20 3 0.0051 0.0056 b4 1 0.0746 0.0470 b21 1 0.0094 0.0059 b5 1 0.0104 0.0065 b22 2 0.0074 0.0057 b6 1 0.0094 0.0059 b23 1 0.0094 0.0059 b7 1 0.0094 0.0059 b24 1 0.0094 0.0059 b8 1 0.0088 0.0056 b25 2 0.0074 0.0057 b9 2 0.02470 0.0190 b26 3 0.0351 0.0385 b10 1 0.0094 0.0059 b27 1 0.0094 0.0059 b11 1 0.0094 0.0059 b28 1 0.0094 0.0059 b12 1 0.0094 0.0059 b29 1 0.0094 0.0059 b13 1 0.0094 0.0059 b30 1 0.0094 0.0059 b14 2 0.0461 0.0353 b31 2 0.0074 0.0057 b15 1 0.0094 0.0059 b32 3 0.0102 0.0112 b16 1 0.0094 0.0059 b33 4 0.0188 0.0589 b17 1 0.0094 0.0059 b34 4 0.0188 0.0589

[0152] The output active power of each power generation unit in the station is set to be in the range of 1.6MW-3.3MW, as shown in Table 3. The output active power of the new energy station is 80.7MW.

[0153] Table 3

[0154] Serial number Power(MW) Serial number Power(MW) Serial number Power(MW) Serial number Power(MW) 1 2.03 9 2.29 17 2.50 25 1.69 2 3.03 10 3.28 18 3.30 26 2.06 3 3.15 11 1.75 19 3.06 27 2.49 4 2.79 12 2.15 20 2.94 28 3.25 5 2.83 13 2.47 21 1.64 29 2.81 6 1.99 14 1.70 22 2.37 30 2.13 7 2.58 15 2.83 23 2.88 31 2.1 8 2.98 16 2.55 24 1.79 32 3.29

[0155] The unit transformer capacity is 3.3MW, and the parameters of the 32 unit transformers are the same, as shown in Table 4.

[0156] Table 4

[0157] Parameter name unit Numeric Rated capacity MVA 3.3 High voltage side rated voltage kV 37±2×25% Low voltage side rated voltage kV 0.8 Short circuit impedance % 4.5 Short circuit loss kW 27.62 No-load current % 2.5 No-load loss kW 2.81

[0158] Set the new energy to be sent out through a 500kV line, the line distance is 400km, the equivalent impedance of the receiving system is 0.1∠85°, set the three-phase short-circuit fault at the end of the 500kV line, and the transition resistance is 0.17pu. Figure 5 The figure shows a detailed model voltage distribution diagram of a new energy station in steady state and during faults.

[0159] As can be seen from Figure 7, at this time, some units in the new energy station enter low voltage ride-through control, and the voltage distribution in the station is calculated using the method of this application. The results are shown in Table 5.

[0160] Table 5

[0161] Serial number Voltage (pu) Serial number Voltage (pu) Serial number Voltage (pu) Serial number Voltage (pu) 1 0.9047 9 0.8992 17 0.8992 25 0.8985 2 0.9051 10 0.9037 18 0.8989 26 0.8985 3 0.9046 11 0.9026 19 0.8979 27 0.8996 4 0.9036 12 0.9025 20 0.8976 28 0.8997 5 0.9016 13 0.9020 21 0.9001 29 0.8991 6 0.9009 14 0.9008 22 0.9005 30 0.8980 7 0.9008 15 0.9001 23 0.9005 31 0.8971 8 0.9004 16 0.8997 24 0.8993 32 0.8962

[0162] like Figure 6 The figure shows a schematic diagram of the comparison of unit status during a new energy station failure.

[0163] Figure 6 In the figure, the left side shows the detailed model unit status of the new energy station, and the right side shows the unit status obtained by the method of this application. It can be seen that the unit status obtained by the method of this application does not enter the low voltage ride-through group 1, which contains 17 units, and the unit status obtained by the method of this application includes 15 units. By comparing the detailed model unit status of the new energy station with the unit status obtained by the method of this application, the low voltage ride-through of each unit, the status of 27 units in the station is accurately judged, with an accuracy rate of 84.5%. The equivalent machine, unit transformer and collector line parameters of groups 1 and 2 are further calculated.

[0164] All the units in the new energy station are divided into two groups: those that have entered low voltage ride through and those that have not entered low voltage ride through. Based on the grouping results of the units, equivalent values ​​are obtained to obtain equivalent unit power Idj, collector line impedance Zdjz, equivalent transformer impedance ZTj, and equivalent transformer capacity STj, as shown in Table 6.

[0165] Table 6

[0166] Parameter name Equivalent machine 1 Equivalent machine 2 Unit transformer capacity (MVA) 56.1MVA 49.5MVA Unit transformer resistance (pu) 0.016 0.018 Unit transformer reactance (pu) 0.0026 0.0023 Line resistance (pu) 0.0193 0.0236 Line reactance (pu) 0.0342 0.0587 Compensation power (pu) -0.0014-0.0069j 0-0.0016j Rated power(pu) 0.3811-0.0069j 0.4245-0.0016j

[0167] The setting values ​​of the steady-state and voltage ride-through control parameters of the equivalent machine are the same as those of the detailed model of the station. The equivalent method proposed in this application is compared with the two-machine equivalent method that does not consider the voltage distribution, as shown in Figure 7.

[0168] in, Figure 7a This is a comparison chart of 35kV bus voltage equivalents at new energy stations; Figure 7b It is a comparison chart of the output active power equivalent of new energy stations; Figure 7c This is a comparison chart of reactive power output equivalents of new energy stations.

[0169] As can be seen from Figure 7, the existing equivalent method does not consider the voltage distribution characteristics inside the new energy station, and cannot distinguish between the units that enter the low voltage ride-through and the units that do not enter the low voltage ride-through, resulting in the equivalent results during the fault period not being able to reflect the dynamic process of the detailed model. The method proposed in this application can better distinguish whether the unit enters the low voltage ride-through, and its performance in steady state, during the fault period, and during the fault recovery process is better than the existing two-machine equivalent method, which fits the dynamic characteristics of the detailed model of the station.

[0170] In summary, the embodiment of the present application provides an equivalent modeling method suitable for the safe and stable operation of a new energy station, including: obtaining the original topological structure, information of each unit and information of the station collector line of the target new energy station; establishing a road matrix T and an impedance matrix Z of the station collector line according to the original topological structure, the information of each unit and the station collector line information; according to the information of each unit and the station collector line information, as well as the road matrix T and the impedance matrix Z, converting the original topological structure into a radial topological structure, and obtaining the equivalent impedance Z of the converter collector line of each unit. b ; When a fault occurs in a new energy station, obtain fault-related information, and calculate the terminal voltage vector U of each unit after the fault according to the fault-related information, the road matrix T and the impedance matrix Z; cluster all units according to the terminal voltage vector U of each unit after the fault and the information of each unit, and divide all units into X cluster groups; obtain the low-voltage side voltage of the main transformer of the target new energy station, and according to the equivalent impedance Z of the converter collector line of each unit b and the information of each unit, respectively perform equivalence on the X cluster groups to obtain an equivalence model of the target new energy station detailed model. The equivalence method of the present application can fit the dynamic characteristics of the new energy station detailed model when the station is in steady state, fault, and fault recovery, which is conducive to ensuring the safe and stable operation of the new energy station.

[0171] In addition, the equivalent method of this application is more convenient to calculate the equivalent parameters of complex station topologies. It only needs to change the road matrix, and the subsequent calculation formula is the same, which can quickly calculate the equivalent parameters of the collector line. The steady-state voltage and fault data of each node can also be used to calculate the detailed voltage distribution according to the station topology, and the status of the units in the station (entering or not entering low voltage crossing) can be judged based on this method, and then grouping and equivalent can be performed. The simulation results under different fault types and voltage drop degrees show that the proposed method has a better equivalent effect in the transient process, which is conducive to ensuring the safe and stable operation of new energy stations.

[0172] Embodiment 2

[0173] Based on the equivalent modeling method disclosed in the above embodiment of the present invention, which is applicable to the safe and stable operation of new energy stations, Figure 8Specifically disclosed is an equivalent modeling system suitable for the safe and stable operation of new energy stations using the equivalent modeling method suitable for the safe and stable operation of new energy stations.

[0174] like Figure 8 As shown, an embodiment of the present invention discloses an equivalent modeling system suitable for safe and stable operation of a new energy station, the system comprising:

[0175] The acquisition unit 801 is used to acquire the original topological structure of the target new energy station, information of each unit and station collection line information;

[0176] An establishing unit 802 is used to establish a road matrix T and an impedance matrix Z of a station collector line according to the original topology structure, the information of each unit and the station collector line information;

[0177] The conversion unit 803 is used to convert the original topology into a radial topology according to the information of each unit and the station collector line information, the road matrix T and the impedance matrix Z, and obtain the equivalent impedance Z of the converter collector line of each unit. b ;

[0178] The calculation unit 804 is used to obtain fault-related information when a fault occurs in the new energy station, and calculate the terminal voltage vector U of each unit after the fault according to the fault-related information, the road matrix T and the impedance matrix Z;

[0179] A clustering unit 805 is used to cluster all the units according to the terminal voltage vector U of each unit after the fault and the information of each unit, and divide all the units into X cluster groups;

[0180] The equivalent unit 806 is used to obtain the low voltage side voltage of the main transformer of the target new energy station, and calculate the equivalent impedance Z of the collector line of the converter of each unit according to the equivalent impedance Z of the converter b and the information of each unit, respectively perform equivalent operations on the X cluster groups to obtain an equivalent model of the target new energy station detailed model.

[0181] In some embodiments, the crew information includes:

[0182] The output current of the converter in the unit, the low voltage side voltage of the transformer, the transformer impedance, the transformer capacity and the active power of the unit. Each unit includes a converter and a transformer connected to the converter.

[0183] In some embodiments, the station collection line information includes:

[0184] Station collection line model, line resistance, and line reactance.

[0185] In some embodiments, the original topology structure includes:

[0186] The target new energy station includes n units, which are connected by collector lines, and there are m line collection points in the collector lines. The low-voltage side of the main transformer of the target new energy station is the root node R, and the original topological structure of the typical tree structure is formed starting from the root node R.

[0187] In some embodiments, the clustering unit is used to determine whether each unit enters a low voltage ride-through state according to the terminal voltage vector U of each unit after the fault, and obtain a judgment result; if the judgment result indicates that all units enter a low voltage ride-through state, then the units are divided into two clustering groups of high power low voltage and low power high voltage according to the unit active power of each unit and the terminal voltage vector U of each unit after the fault; if the judgment result indicates that not all units enter a low voltage ride-through state, then all units are divided into two groups according to whether they enter a low voltage ride-through, and the group to which the units entering the low voltage ride-through belong is grouped again according to a preset ratio threshold and the unit active power, and finally X clustering groups are obtained.

[0188] For the specific working process of the acquisition unit 801, the establishment unit 802, the conversion unit 803, the calculation unit 804, the clustering unit 805 and the equivalent unit 806 in the equivalent modeling system for safe and stable operation of the new energy station disclosed in the above embodiment of the present invention, please refer to the corresponding content in the equivalent modeling method for safe and stable operation of the new energy station disclosed in the above embodiment of the present invention, which will not be repeated here.

[0189] In summary, the embodiment of the present application provides an equivalent modeling system suitable for the safe and stable operation of a new energy station, including: obtaining the original topological structure, information of each unit and information of the station collector line of the target new energy station; establishing a road matrix T and an impedance matrix Z of the station collector line according to the original topological structure, the information of each unit and the station collector line information; according to the information of each unit and the station collector line information, as well as the road matrix T and the impedance matrix Z, converting the original topological structure into a radial topological structure, and obtaining the equivalent impedance Z of the converter collector line of each unit. b ; When a fault occurs in a new energy station, obtain fault-related information, and calculate the terminal voltage vector U of each unit after the fault according to the fault-related information, the road matrix T and the impedance matrix Z; cluster all units according to the terminal voltage vector U of each unit after the fault and the information of each unit, and divide all units into X cluster groups; obtain the low-voltage side voltage of the main transformer of the target new energy station, and according to the equivalent impedance Z of the converter collector line of each unitb and the information of each unit, respectively perform equivalence on the X cluster groups to obtain an equivalence model of the target new energy station detailed model. The equivalence method of the present application can fit the dynamic characteristics of the new energy station detailed model when the station is in steady state, fault, and fault recovery, which is conducive to ensuring the safe and stable operation of the new energy station.

[0190] In the several embodiments provided in the present application, it should be understood that the disclosed method can also be implemented in other ways. The method embodiments described above are merely illustrative.

[0191] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0192] Although the implementation methods disclosed in this application are as above, the above contents are only the implementation methods adopted for facilitating the understanding of this application, and are not intended to limit this application. Any technician in the technical field to which this application belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this application, but the scope of patent protection of this application shall still be based on the scope defined in the attached claims.

Claims

1. An equivalent modeling method suitable for the safe and stable operation of new energy stations, characterized in that: The method comprises: Obtain the original topological structure of the target new energy station, information about each unit, and information about the station's power collection lines; Crew information includes: The output current of the converter in the unit, the voltage on the low voltage side of the transformer, the transformer impedance, the transformer capacity and the active power of the unit, where each unit includes a converter and a transformer connected to the converter; According to the original topological structure, the information of each unit and the information of the station collection line, a road matrix T and an impedance matrix Z of the station collection line are established; According to the information of each unit and the station collector line information, as well as the road matrix T and the impedance matrix Z, the original topology is converted into a radial topology to obtain the equivalent impedance Z of the converter collector line of each unit. b ; The equivalent impedance vector of the collector line of the converter : In the formula, is the equal-value road matrix, is the equivalent impedance vector of the branch; When a fault occurs at the new energy station, fault-related information is obtained, and a terminal voltage vector U of each unit after the fault is calculated based on the fault-related information, the road matrix T and the impedance matrix Z; All the units are clustered according to the terminal voltage vector U of each unit after the fault and the information of each unit, and all the units are divided into X cluster groups, including: According to the terminal voltage vector U of each unit after the fault, whether each unit enters the low voltage ride-through state is determined to obtain a determination result; If the judgment result indicates that all units have entered the low voltage ride-through state, the units are divided into two clusters of high power low voltage and low power high voltage according to the unit active power of each unit and the terminal voltage vector U of each unit after the fault; If the judgment result indicates that not all units have entered the low voltage ride-through state, all units are divided into two groups according to whether they have entered the low voltage ride-through state, and the group of units entering the low voltage ride-through state is grouped again according to the preset ratio threshold and the active power of the units, and finally X cluster groups are obtained; Obtain the low-voltage side voltage of the main transformer of the target new energy station, and calculate the equivalent impedance Z of the converter collector line of each unit according to the impedance Z of the converter collector line of each unit. b and the information of each unit, respectively perform equivalent operations on the X cluster groups to obtain an equivalent model of the target new energy site detailed model.

2. The method according to claim 1, characterized in that: The station collection line information includes: Station collection line model, line resistance, and line reactance.

3. The method according to claim 1, characterized in that The original topological structure includes: The target new energy station includes n units, which are connected by collector lines, and there are m line collection points in the collector lines. The low-voltage side of the main transformer of the target new energy station is the root node R, and the original topological structure of the typical tree structure is formed starting from the root node R.

4. An equivalent modeling system suitable for safe and stable operation of new energy stations, characterized in that: The equivalent modeling system is used to implement the equivalent modeling method applicable to the safe and stable operation of the new energy station as described in any one of claims 1 to 3; The system comprises: The acquisition unit is used to acquire the original topological structure of the target new energy station, the information of each unit and the station collection line information; the unit information includes: The output current of the converter in the unit, the voltage on the low voltage side of the transformer, the transformer impedance, the transformer capacity and the active power of the unit, where each unit includes a converter and a transformer connected to the converter; An establishing unit, used for establishing a road matrix T and an impedance matrix Z of a station collector line according to the original topological structure, the information of each unit and the station collector line information; A conversion unit is used to convert the original topology into a radial topology according to the information of each unit and the station collector line information, the road matrix T and the impedance matrix Z, and obtain the equivalent impedance Z of the converter collector line of each unit. b ; A calculation unit, used for obtaining fault-related information when a fault occurs in a new energy station, and calculating a terminal voltage vector U of each unit after the fault according to the fault-related information, the road matrix T and the impedance matrix Z; A clustering unit is used to cluster all the units according to the terminal voltage vector U of each unit after the fault and the information of each unit, and divide all the units into X cluster groups; the clustering unit is used to judge whether each unit enters the low voltage ride-through state according to the terminal voltage vector U of each unit after the fault, and obtain a judgment result; if the judgment result indicates that all units enter the low voltage ride-through state, then according to the unit active power of each unit and the terminal voltage vector U of each unit after the fault, the units are divided into two cluster groups of high power low voltage and low power high voltage; if the judgment result indicates that not all units enter the low voltage ride-through state, then all units are divided into two groups according to whether they enter the low voltage ride-through, and the group of the units entering the low voltage ride-through is grouped again according to the preset ratio threshold and the unit active power, and finally X cluster groups are obtained; The equivalent unit is used to obtain the low-voltage side voltage of the main transformer of the target new energy station, and according to the equivalent impedance Z of the converter collector line of each unit b and the information of each unit, respectively perform equivalent operations on the X cluster groups to obtain an equivalent model of the target new energy site detailed model.

5. The system according to claim 4, characterized in that The station collection line information includes: Station collection line model, line resistance, and line reactance.

6. The system according to claim 4, characterized in that The original topological structure includes: The target new energy station includes n units, which are connected by collector lines, and there are m line collection points in the collector lines. The low-voltage side of the main transformer of the target new energy station is the root node R, and the original topological structure of the typical tree structure is formed starting from the root node R.

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