Simplified equivalent method, storage medium and equipment for high-proportion new energy DC transmission power grid

Abstract

The invention discloses a simplified equivalent method, storage medium and device for a DC power grid with a high proportion of new energy, belonging to the technical field of power system modeling. In order to solve the problem that the current power system simplification method is less practical in a DC power grid with a high proportion of new energy, the invention first determines the scope and network of the retained power grid, counts and divides the low-voltage level loads and generators; then divides the low-voltage network components by type, and determines the equivalent structure of the low-voltage network; then, obtains the parameters of the low-voltage network components, that is, obtains the equivalent parameters of the new energy generator, the equivalent three-winding transformer, the equivalent machine-end transformer parameters, the equivalent load, the equivalent capacitance reactance and the equivalent line; finally, sets the balancing node and the flow section, builds the PSASP power grid model and balances the flow, and forms a simplified model of the DC power grid with a high proportion of new energy.

Description

Technical Field

[0001] The present invention belongs to the technical field of power system modeling, and relates to a simplified equivalent method, storage medium and equipment for a new energy direct current sending-end power grid. Background Art

[0002] The simplified equivalent methods of power systems include the synchronous equivalent method, physical equivalent method, model equivalent method and estimated equivalent method. Currently, the synchronous equivalent method and physical equivalent method are the most widely used. The synchronous equivalent method divides the synchronous generators into the same synchronous group and aggregates the synchronous group. This method is suitable for simplifying traditional power grids with synchronous generators as the main power source, but cannot be applied to multi-feed AC / DC hybrid power grids. The physical equivalent method mainly focuses on the main grid with voltage levels of 500kV and above, and divides all generators in the low-voltage network at the same 500kV voltage level into a synchronous group. This method is more complicated to implement when simplifying the DC sending-end power grid with a high proportion of renewable energy. In existing studies, there is no mention of how to improve the grid equivalent in the new energy gathering area at the DC sending end. Relying only on the existing grid equivalent method, it is not possible to simplify the grid while meeting the simulation accuracy requirements of the power system with a high proportion of renewable energy. For this reason, a simplified equivalent method for the DC sending-end power grid with a high proportion of renewable energy is needed to reduce the system scale while meeting the grid simulation accuracy. Summary of the invention

[0003] In order to solve the problem that the current power system simplification method has poor practicality in the DC sending-end power grid containing a high proportion of renewable energy.

[0004] A simplified equivalent method for a high-proportion new energy DC sending-end power grid comprises the following steps:

[0005] Step 1: Based on the fault simulation results of the original power grid, the internal and external networks are divided according to the transient overvoltage of the busbar under the DC bipolar blocking fault, and the DC near-zone power grid area to be retained is divided into the internal network, and the rest is divided into the external network;

[0006] According to the voltage level of the original power grid, high and low voltage grids are divided;

[0007] According to the above classification standards, the medium and high voltage grid of the internal network is retained as the backbone grid;

[0008] Step 2: The loads and generators in the low-voltage grid of the original power grid are assigned to the adjacent high-voltage busbars, and the power flow of the original power grid is counted as the initial power flow. According to the principle that the active power distribution of the power flow of the main grid after the assignment remains unchanged, the division results of the loads and generators are adjusted;

[0009] Step 3: For the main grid, retain the generators, DC lines, capacitors and reactances directly connected to the main grid and the conventional power supply connected to the low-voltage busbar, simplify the low-voltage grid in the inner network, and form a typical collection station equivalent structure;

[0010] Step 4: The conventional units are directly connected to the low-voltage busbar, and the new energy units are aggregated to form equivalent new energy units connected to the low-voltage busbar;

[0011] Step 5. After the original internal network is equalized, continue to equalize the external network and find the high-voltage level line connecting the internal network and the external network. According to the power of the corresponding line, the external network is equalized to the synchronous machine with the same power, and the synchronous machine with the largest power is set as the balancing machine. The bus connected to the synchronous machine is the balancing node.

[0012] Furthermore, the criterion for dividing the inner and outer networks according to the transient overvoltage of the bus under a DC bipolar blocking fault is whether the transient overvoltage of the bus under a DC bipolar blocking fault reaches 1.3pu. The area reaching 1.3pu is the DC near-zone power grid area to be retained and is divided into the inner network, and the rest is the outer network.

[0013] Furthermore, in the process of dividing the high and low voltage grids according to the voltage level of the original power grid, the high voltage grid is a power grid of 500 kV and above, and the low voltage grid is a power grid below 500 kV.

[0014] Furthermore, the typical aggregation station equivalent structure formed in step 3 includes:

[0015] Conventional units, equivalent new energy units, equivalent loads, equivalent three-winding transformers, equivalent machine-end transformers, equivalent capacitors and reactances, equivalent lines and busbars in the low-voltage grid under the collection station; among them,

[0016] The conventional units in the low-voltage grid under the collection station are the same as the original grid;

[0017] The equivalent load is obtained by adding the loads in the low-voltage grid under the collection station;

[0018] The equivalent three-winding transformer and the equivalent machine-end transformer are calculated using the capacity weighting method;

[0019] The equivalent capacitive reactance is obtained by adding the capacitive reactance in the low-voltage grid under the collection station;

[0020] The equivalent lines are calculated using the capacity weighted method.

[0021] Furthermore, in the process of aggregating the new energy units in step 4, the new energy units of the same type are aggregated and equalized.

[0022] Furthermore, in the process of aggregating and equating the new energy units of the same type, the parameters of the equivalent new energy units include the operating parameters of the equivalent new energy units, and the operating parameters of the equivalent new energy units are calculated as follows:

[0023] Assuming that a group contains h renewable energy units, the equivalent wind speed / light intensity of a single renewable energy unit in the group is expressed as:

[0024]

[0025] In the formula, Indicates the wind speed / light intensity of a single renewable energy unit, subscript l Indicates the new energy unit number, It indicates the equivalent wind speed / light intensity after the group of new energy units are equivalent to one equivalent unit; f Represents the wind / solar power function of the new energy unit.

[0026] Furthermore, in the process of aggregating and valuing the same type of new energy units, the equivalent new energy unit parameters include the body parameters of the equivalent new energy unit, and the body parameters of the equivalent new energy unit include the equivalent generator parameters, shaft system parameters and transformer parameters. The calculation process is as follows:

[0027] The equivalent generator parameters are expressed as:

[0028]

[0029] In the formula, S Indicates the capacity of a single generator; the subscript "eq" represents equal value, is the equivalent generator capacity; x 1 、x 2 They represent the stator reactance and rotor reactance of the generator respectively; r 1 、r 2 They represent the stator resistance and rotor resistance of the generator respectively; x m represents the generator magnetizing reactance;

[0030] The axis parameters are expressed as:

[0031]

[0032] In the formula, H g represents the rotor inertia constant of the generator; H t represents the rotor inertia constant of the wind turbine; K srepresents the shafting stiffness coefficient;

[0033] The transformer parameters are expressed as:

[0034]

[0035] In the formula, S T Indicates the transformer capacity, Z T Represents the transformer impedance.

[0036] Furthermore, in the process of aggregating and valuing the new energy units of the same type, the parameters of the equivalent new energy units include the collector network parameters of the equivalent new energy units, wherein the calculation process of the collector network parameters of the equivalent new energy units is as follows:

[0037] The parameters of the collector network are equivalent based on the principle that the injected current and power of the nodes before and after are equal. h The equivalent value of a unit is one equivalent unit;

[0038] Before and after the equalization, the injected current and power of the node are equal, which means that the current and power emitted by the equalization machine are equal to the sum of the current and power emitted by all the units in the group before the equalization;

[0039] Equivalent voltage at the equivalent machine end It is expressed as:

[0040]

[0041] The equivalent impedance of the collector network corresponding to the equivalent machine is:

[0042]

[0043] In the formula, represents the equivalent impedance of the collector network of the equivalent machine; Represents the voltage at the common node.

[0044] A computer storage medium stores at least one instruction, which is loaded and executed by a processor to implement a simplified equivalent method for a high-proportion new energy DC sending-end power grid.

[0045] A simplified equivalent device for a high-proportion new energy DC sending-end power grid, the device comprising a processor and a memory, the memory storing at least one instruction, the at least one instruction being loaded and executed by the processor to implement the simplified equivalent method for a high-proportion new energy DC sending-end power grid.

[0046] The present invention first determines the scope and network of the reserved power grid, counts and divides the low-voltage level loads and generators; then divides the low-voltage network components by type, and determines the equivalent structure of the low-voltage network; then, obtains the parameters of the low-voltage network components, that is, obtains the equivalent parameters of the new energy generator, the equivalent three-winding transformer, the equivalent machine-end transformer parameters, the equivalent load, the equivalent capacitance reactance and the equivalent line; finally, sets the balance node and the flow section, builds the PSASP power grid model and balances the flow, and forms a simplified model of the high-proportion new energy DC sending-end power grid. The present invention can simplify the equivalent complex high-proportion new energy DC sending-end power grid model, not only provides an effective model support for the stability analysis of the power grid, but also has good practicality in the DC sending-end power grid containing a high proportion of new energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Flowchart established for the simplified model of power grid equivalent;

[0048] Figure 2 This is the equivalent structure diagram of a typical collection station;

[0049] Figure 3 This is a schematic diagram of a single new energy equivalent machine;

[0050] Figure 4 This is a 500kV grid structure diagram of a DC sending-end power grid;

[0051] Figure 5 It is the transient response curve diagram of DC bipolar blocking voltage before and after equalization;

[0052] Figure 6 It is the transient response curve diagram of DC unipolar blocking voltage before and after equalization;

[0053] Figure 7 It is the transient response curve of DC commutation failure voltage before and after equalization. DETAILED DESCRIPTION

[0054] In order to solve the problem that the current power system simplification method is less practical in the DC sending-end power grid containing a high proportion of new energy (the power grid with a new energy power generation capacity of more than 15% belongs to a high proportion of new energy power grid), the present invention proposes a simplified equivalent method for the DC sending-end power grid with a high proportion of new energy, by aggregating low-voltage network components by type under the collection station to simplify the complex equivalent model of the DC sending-end power grid with a high proportion of new energy. The present invention divides the low-voltage network components by type, proposes an equivalent structure of a typical collection station, and combines the calculation of new energy equivalent machine parameters with the calculation of collection network equivalent parameters to establish an equivalent simplified model of the DC sending-end power grid. It has been verified by a certain actual DC sending-end power grid containing a high proportion of new energy that the proposed method can simplify the power grid while meeting the simulation accuracy requirements of the power system, verifying the effectiveness of the proposed method. The present invention is further described below in conjunction with specific implementation methods.

[0055] Specific implementation method: Figure 1 , Attachment Figure 2 and attached Figure 3 This embodiment will be described.

[0056] The simplified equivalent method of a high-proportion new energy DC sending-end power grid described in this embodiment includes the following steps:

[0057] Step 1: Based on the fault simulation results of the original power grid, the inner and outer networks are divided. The DC near-zone power grid area to be retained is divided into the inner network, and the rest is divided into the outer network (the division standard is whether the transient overvoltage of the bus under the DC bipolar blocking fault reaches 1.3pu. Those that reach 1.3pu are divided into the inner network, and the rest are the outer network);

[0058] According to the voltage level of the original power grid, high and low voltage grids are divided (in the present invention, the high voltage grid is a grid of 500 kV and above, and the low voltage grid is a grid below 500 kV);

[0059] According to the above classification standards, the high voltage level grid of the internal network is retained as the backbone grid, and the equivalent remaining grid structure is simplified.

[0060] Step 2: Assign the loads and generators in the low-voltage grid of the original power grid to the adjacent high-voltage busbar, and calculate the flow of the original power grid as the initial flow. According to the principle that the active power distribution of the main grid after the calculation remains unchanged, adjust the division results of the loads and generators.

[0061] Step 3: For the main grid, after retaining the generators, DC lines, capacitors and reactances directly connected to the main grid and the conventional power supply (specific professional terminology) connected to the low-voltage bus, it is necessary to simplify the low-voltage grid in the internal network to form a typical collection station equivalent structure.

[0062] Typical collection station equivalent structure is as follows Figure 2 As shown, it includes: conventional units in the low-voltage grid under the collection station, equivalent new energy units, equivalent loads, equivalent three-winding transformers, equivalent machine-end transformers, equivalent capacitors and reactances, equivalent lines and busbars (high-voltage busbar, low-voltage busbar, generator busbar, load busbar).

[0063] Among them, the conventional units in the low-voltage grid under the collection station are the same as the original power grid; the equivalent load is obtained by adding the loads in the low-voltage grid under the collection station; the equivalent three-winding transformer and the equivalent machine-end transformer are calculated using the capacity weighted method; the equivalent capacitive reactance is obtained by adding the capacitive reactance in the low-voltage grid under the collection station; the equivalent line is calculated using the capacity weighted method.

[0064] Step 4: Conventional units have large capacity and small number, and can be directly connected to the low-voltage busbar. However, new energy units have small capacity and large number, and need to be aggregated to form equivalent new energy units to be connected to the low-voltage busbar. The present invention aggregates the same type of new energy units to be equivalent, and the parameters of the equivalent new energy units are divided into the operating parameters, body parameters and collector network parameters of the equivalent new energy units. The operating parameter calculation process of the equivalent new energy units is as follows:

[0065] The operating parameters of the equivalent new energy units are equivalent wind speed / light (wind turbine units are wind speed, photovoltaic units are light), which is the equivalent wind speed / light corresponding to the average power of the sum of the outputs of all new energy units in the group. The specific process is as follows:

[0066] Assuming that a group contains h renewable energy units, the equivalent wind speed / sunlight of a single renewable energy unit in the group can be expressed as:

[0067]

[0068] In the formula, Indicates the wind speed / light intensity of a single renewable energy unit, subscript l Indicates the new energy unit number, It indicates the equivalent wind speed / light intensity after the group of new energy units are equivalent to one equivalent unit; f Represents the wind / solar power function of the new energy unit.

[0069] The body parameters of the equivalent new energy unit are divided into equivalent generator parameters, shaft system parameters and transformer parameters. The calculation process is as follows:

[0070] The equivalent generator parameters can be expressed as:

[0071]

[0072] In the formula, S represents the capacity of a single generator; the subscript "eq" represents the equivalent value, is the equivalent generator capacity; x 1 、x 2 They represent the stator reactance and rotor reactance of the generator respectively; r 1 、r 2 They represent the stator resistance and rotor resistance of the generator respectively; x m Represents the generator magnetizing reactance.

[0073] The axis parameters can be expressed as:

[0074]

[0075] In the formula, H g represents the rotor inertia constant of the generator; H t represents the rotor inertia constant of the wind turbine; K s Represents the shafting stiffness coefficient.

[0076] The transformer parameters can be expressed as:

[0077]

[0078] In the formula, S T Indicates the transformer capacity, Z T Represents the transformer impedance.

[0079] The calculation process of the collector network parameters of the equivalent new energy unit is as follows:

[0080] The parameters of the collector network are equivalent based on the principle that the injected current and power of the nodes before and after are equal. Figure 3 As shown, assuming h The value of a unit is equal to one equivalent unit.

[0081] Before and after the equalization, the injected current and power of the node are equal, which means that the current and power emitted by the equalization machine are equal to the sum of the current and power emitted by all units in the group before the equalization. Then the equivalent power and equivalent current corresponding to the equivalent machine can be expressed as:

[0082]

[0083] In the formula, Indicates the complex power of a single fan; Indicates the voltage of a single fan; Indicates the current of a single fan; represents the complex power of the equivalent machine; represents the current of the isotype machine; the superscript * indicates conjugation.

[0084] Then the equivalent voltage at the equivalent machine end is It can be expressed as:

[0085]

[0086] According to Ohm's law, the equivalent impedance of the collector network corresponding to the equivalent machine is:

[0087]

[0088] In the formula, represents the equivalent impedance of the collector network of the equivalent machine; Represents the voltage at the common node.

[0089] Step 5. After processing the equivalent of the network in the original power grid, the next step is to equivalent the external network, find the high-voltage level line connecting the internal network and the external network, and according to the power of the corresponding line, the external network is equivalent to the synchronous machine with the same power, and the synchronous machine with the largest power is set as the balancing machine. The bus connected to the synchronous machine is the balancing node.

[0090] Step 6. Based on the equivalents of the above steps, a simplified equivalent model of the high-proportion renewable energy DC sending-end power grid can be obtained. The simplified power grid model (including the high-voltage main grid of the internal network, the equivalent grids of each collection station and their equivalent components, and the equivalent synchronous machine of the external network) is built in PSASP, and the simplified power grid flow is balanced according to the flow data of the original power grid model.

[0091] Example

[0092] Use attached Figure 4 Taking a high-proportion new energy DC sending-end power grid as an example, it is equivalently simplified and a simplified DC sending-end power grid model is built in PSASP.

[0093] The steady-state characteristics of the original model and the simplified model are compared, the bus voltages and trunk line flows of each high voltage level are statistically analyzed, and the errors and mean absolute errors are calculated, as shown in Tables 1 and 2.

[0094] Table 1 Comparison of bus voltages of various high voltage levels before and after equalization

[0095]

[0096]

[0097]

[0098] Table 2 Comparison of active power of trunk lines before and after equalization

[0099]

[0100] From Table 1 and Table 2, it can be seen that the maximum error of the high voltage bus voltage in the grid is 0.43% in steady state, and the average absolute error is 0.10%; the error of the active power of the trunk line is within 14.34%, and the average absolute error is 1.98%. It can be seen that the simplified model has the same steady-state power flow characteristics as the original model.

[0101] By comparing the transient characteristics of the original model and the simplified model, the short-circuit currents of the high-voltage buses in the system before and after the equalization are first counted, and the errors and mean absolute errors are calculated, as shown in Table 3.

[0102] Table 3 Comparison of short-circuit current of each high voltage level busbar in the system before and after equalization

[0103]

[0104]

[0105]

[0106] It can be seen from Table 3 that the error of the short-circuit current of each high-voltage busbar in the system before and after the equalization is within 13.03%, and the average absolute error is 3.42%, which is within the acceptable error range.

[0107] The simulation was carried out in the original model and the simplified model, and the DC bipolar blocking, unipolar blocking and single commutation failure faults were set respectively. The transient response curves of the DC sending end bus voltage and the DC near-zone new energy collection area bus voltage before and after the equivalent value were compared. The simulation results are shown in the attached figure. Figure 5 , Attachment Figure 6 and attached Figure 7 As shown in the figure, the transient corresponding trends and amplitudes of the voltages of the sending-end bus and some buses in the DC near-zone new energy collection area are basically consistent. The transient overvoltage and low-high voltage interlocking simulation data of the model before and after the equivalent value are checked, and the results are shown in Table 4.

[0108] Table 4 Comparison of system failures before and after equalization

[0109]

[0110] It can be seen from Table 4 that the errors of overvoltage and low-high voltage interlocking of the sending-end bus and some buses in the DC near-zone new energy collection area caused by system faults before and after the equivalent value are all within 5.96%, and the average absolute error is 4.47%. It can be considered that the simplified model has the same steady-state characteristic trend as the original power grid model.

[0111] In summary, the present invention proposes a simplified equivalent method for a DC sending-end power grid with a high proportion of new energy, thereby achieving equivalent simplification of a complex DC sending-end power grid model. Specific implementation method 2:

[0113] This embodiment is a computer storage medium, in which at least one instruction is stored. The at least one instruction is loaded and executed by a processor to implement the simplified equivalent method of a high-proportion new energy DC sending-end power grid.

[0114] It should be understood that the instructions include computer program products, software or computerized methods corresponding to any method described in the present invention; the instructions can be used to program a computer system, or other electronic device. Computer storage media may include readable media on which instructions are stored, which may include but are not limited to magnetic storage media, optical storage media; magneto-optical storage media include read-only memory ROM, random access memory RAM, erasable programmable memory (e.g., EPROM and EEPROM) and flash memory layers, or other types of media suitable for storing electronic instructions. Specific implementation method three:

[0116] This embodiment is a simplified equivalent device of a high-proportion new energy DC sending-end power grid, the device includes a processor and a memory. It should be understood that including any device including a processor and a memory described in the present invention, the device may also include other units and modules that perform display, interaction, processing, control, etc. and other functions through signals or instructions;

[0117] At least one instruction is stored in the memory, and the at least one instruction is loaded and executed by the processor to implement the simplified equivalent method of the high-proportion new energy DC sending-end power grid.

[0118] Those skilled in the art will appreciate that at least one instruction stored is a computer program product corresponding to the method or system. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The solutions in the embodiments of the present application may be implemented in various computer languages, for example, object-oriented programming language Java and interpreted scripting language JavaScript, etc.

[0119] The present application is described with reference to the flowcharts and / or block diagrams of the methods, systems, and computer program products according to the embodiments of the present application, and may also be used for corresponding devices. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0120] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0121] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0122] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0123] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A simplified equivalent method for a high-proportion new energy DC sending-end power grid, characterized in that: The following steps are involved: Step 1: Based on the fault simulation results of the original power grid, the internal and external networks are divided according to the transient overvoltage of the busbar under the DC bipolar blocking fault. The division standard is whether the transient overvoltage of the busbar under the DC bipolar blocking fault reaches 1.3pu. The area reaching 1.3pu is the DC near-zone power grid area to be retained and is divided into the inner network, and the rest is the outer network; According to the voltage level of the original power grid, high and low voltage grids are divided, wherein the high voltage grid is a grid of 500 kV and above, and the low voltage grid is a grid below 500 kV; According to the above classification standards, the medium and high voltage grid of the internal network is retained as the backbone grid; Step 2: The loads and generators in the low-voltage grid of the original power grid are assigned to the adjacent high-voltage busbars, and the power flow of the original power grid is counted as the initial power flow. According to the principle that the active power distribution of the power flow of the main grid after the assignment remains unchanged, the division results of the loads and generators are adjusted; Step 3: For the main grid, retain the generators, DC lines, capacitors and reactances directly connected to the main grid and the conventional power supply connected to the low-voltage busbar, simplify the low-voltage grid in the inner network, and form a typical collection station equivalent structure; Step 4: The conventional units are directly connected to the low-voltage busbar, and the new energy units are aggregated to form equivalent new energy units connected to the low-voltage busbar; Step 5. After the original internal network is equalized, continue to equalize the external network and find the high-voltage level line connecting the internal network and the external network. According to the power of the corresponding line, the external network is equalized to the synchronous machine with the same power, and the synchronous machine with the largest power is set as the balancing machine. The bus connected to the synchronous machine is the balancing node.

2. A simplified equivalent method for a high-proportion new energy DC sending-end power grid according to claim 1, characterized in that: The typical equivalent structure of the collection station formed in step 3 includes: Conventional units, equivalent new energy units, equivalent loads, equivalent three-winding transformers, equivalent machine-end transformers, equivalent capacitors and reactances, equivalent lines and busbars in the low-voltage grid under the collection station; among them, The conventional units in the low-voltage grid under the collection station are the same as the original grid; The equivalent load is obtained by adding the loads in the low-voltage grid under the collection station; The equivalent three-winding transformer and the equivalent machine-end transformer are calculated using the capacity weighting method; The equivalent capacitive reactance is obtained by adding the capacitive reactance in the low-voltage grid under the collection station; The equivalent lines are calculated using the capacity weighted method.

3. A simplified equivalent method for a high-proportion new energy DC sending-end power grid according to any one of claims 1 to 2, characterized in that: In the process of aggregating the new energy units in step 4, the new energy units of the same type are aggregated and equalized.

4. The simplified equivalent method of a high-proportion new energy DC sending-end power grid according to claim 3 is characterized in that: In the process of aggregating and equating the new energy units of the same type, the parameters of the equivalent new energy units include the operating parameters of the equivalent new energy units. The calculation process of the operating parameters of the equivalent new energy units is as follows: Assuming that a group contains h renewable energy units, the equivalent wind speed / light intensity of a single renewable energy unit in the group is expressed as: Where, ν l represents the wind speed / sunlight of a single renewable energy unit, subscript l represents the renewable energy unit number, ν eq It represents the equivalent wind speed / light intensity after the group of new energy units are equivalent to one equivalent unit; f represents the wind / light power function of the new energy unit.

5. The simplified equivalent method of a high-proportion new energy DC sending-end power grid according to claim 4 is characterized in that: In the process of aggregating and equating the new energy units of the same type, the parameters of the equivalent new energy units include the body parameters of the equivalent new energy units, and the body parameters of the equivalent new energy units include the equivalent generator parameters, shaft system parameters and transformer parameters. The calculation process is as follows: The equivalent generator parameters are expressed as: Where S represents the capacity of a single generator; the subscript "eq" represents the equivalent value, S eq is the equivalent generator capacity; x1 and x2 represent the generator stator reactance and rotor reactance respectively; r1 and r2 represent the generator stator resistance and rotor resistance respectively; x m represents the generator magnetizing reactance; The axis parameters are expressed as: In the formula, H g Represents the rotor inertia constant of the generator; H t Represents the rotor inertia constant of the wind turbine; K s represents the shafting stiffness coefficient; The transformer parameters are expressed as: In the formula, S T Indicates the transformer capacity, Z T Represents the transformer impedance.

6. A simplified equivalent method for a high-proportion new energy DC transmission-end power grid according to claim 5, characterized in that: In the process of aggregating and valuing new energy units of the same type, the parameters of the equivalent new energy units include the collector network parameters of the equivalent new energy units. The calculation process of the collector network parameters of the equivalent new energy units is as follows: The parameters of the collector network are equivalent based on the principle that the injected current and power of the nodes before and after the equivalent value are equal, assuming that h units are equivalent to one equivalent unit; Before and after the equalization, the injected current and power of the node are equal, which means that the current and power emitted by the equalization machine are equal to the sum of the current and power emitted by all the units in the group before the equalization; Equivalent voltage at the equivalent machine end It is expressed as: The equivalent impedance of the collector network corresponding to the equivalent machine is: In the formula, represents the equivalent impedance of the collector network of the equivalent machine; Represents the voltage at the common node.

7. A computer storage medium, characterized in that: The storage medium stores at least one instruction, and the at least one instruction is loaded and executed by the processor to implement the simplified equivalent method of a high-proportion new energy DC sending-end power grid as described in any one of claims 1 to 6.

8. A simplified equivalent device for a high-proportion new energy DC sending-end power grid, characterized in that: The device includes a processor and a memory, wherein the memory stores at least one instruction, and the at least one instruction is loaded and executed by the processor to implement a simplified equivalent method for a high-proportion new energy DC sending-end power grid as described in any one of claims 1 to 6.

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