Power limit calculation method and device for power transmission network
By performing voltage phase locking and topological equivalents to the grid-connected points of the new energy power generation station, a grid-equivalent circuit is formed, which solves the problem of inaccurate calculation of the active power limit during reactive compensation of the new energy station, and improves the accuracy of calculations Sex and stability.
Patent Information
- Application Number
- CN202411437702.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-15
- Publication Date
- 2024-12-20
AI Technical Summary
When the existing active power limit calculation method is missing the reactive power compensation device of the new energy station, the calculation results are not accurate enough, resulting in dynamic changes in the active power limit and is difficult to apply.
By voltage-locking the network connection points of the new energy power generation station, the equivalent topology is simplified, the grid equivalent circuit is formed, the active power data is determined, and the active power limit value is calculated based on these data.
It improves the accuracy of the calculation of active power limits and provides an effective data reference for the stable operation of the flexible DC transmission system of the new energy power station.
Smart Images
Figure CN119171434A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of power grid power calculation, and in particular to a method and device for calculating the power limit of a transmission network. Background Art
[0002] At present, the installed capacity and power generation ratio of new energy sites such as wind power and solar power are gradually increasing. New energy sites can be directly connected to the AC grid through inverters. Considering that the scale of new energy sites is constantly expanding and they are usually far away from the load center, the flexible DC system based on modular multilevel converters can realize the long-distance transmission of large-scale renewable energy power generation.
[0003] When there is sufficient reactive power compensation in the power grid system, the grid connection point of the new energy station can always be maintained near the rated voltage. However, when there is no reactive power compensation device in the new energy station, the voltage at the new energy grid connection point changes with the output power, and will obviously deviate from the rated voltage when the output power is large. This causes the active power limit to change dynamically, making the existing active power limit calculation method difficult to apply and the calculation result is not accurate enough. Summary of the invention
[0004] In view of this, the present invention provides a method and device for calculating the power limit of a transmission network, which solves the technical problem that the existing active power limit calculation method is not accurate enough.
[0005] A first aspect of the present invention provides a method for calculating a power limit of a transmission network, comprising:
[0006] Phase-lock the voltage at the grid connection point of the new energy power station, simplify and equate the topological structure contained in the grid connection area of the new energy power station and the flexible DC system, and obtain the equivalent circuit of the power grid and the equivalent parameters of each equivalent structure in the equivalent circuit of the power grid;
[0007] Determining active power data that changes with current at a grid connection point of the new energy power generation station according to the grid equivalent circuit;
[0008] The active power limit value is determined based on the active power data that varies with the current.
[0009] Preferably, the step of phase-locking the voltage at the grid connection point of the new energy power generation station, simplifying and equilibrating the topological structure contained in the grid connection area of the new energy power generation station and the flexible DC system, and obtaining the grid equivalent circuit and equivalent parameters of each equivalent structure in the grid equivalent circuit includes:
[0010] Phase-locking the voltage at the grid connection point of the new energy power generation station, and treating the new energy power generation station as a current source according to the voltage at the grid connection point after phase locking;
[0011] The flexible DC sending-end converter station in the flexible DC system is equivalent to a voltage source according to the voltage at the grid connection point after phase locking;
[0012] The connecting element between the new energy power generation station and the flexible DC sending-end converter station is equivalent to an equivalent reactance, and the current source is connected to the voltage source through the equivalent reactance to form a loop, thereby forming an equivalent circuit of a power grid.
[0013] Preferably, the equivalent parameters of the current source are:
[0014]
[0015] In the formula, is the output current of the current source, I is the measured amplitude of the current at the grid connection point of the new energy power station, The angle at which the current measured at the grid connection point of a new energy power station leads the voltage measured at the grid connection point. , are respectively the active current component and reactive current component of the current source, and j is the imaginary unit; among them,
[0016]
[0017] In the formula, is the angular frequency, t is the time, The voltage measured at the grid-connected point leads the phase of the current measured at the grid-connected point.
[0018] Preferably, the equivalent parameters of the voltage source are:
[0019]
[0020] In the formula, is the voltage of the voltage source, is the voltage amplitude measured at the flexible DC sending-end converter station, β is the angle at which the measured voltage at the flexible DC sending-end converter station lags behind the measured voltage at the new energy station grid connection point, , are the active voltage component and reactive voltage component of the voltage source respectively; among them,
[0021]
[0022] In the formula, is the angular frequency, t is the time, The voltage measured at the grid-connected point leads the phase of the current measured at the grid-connected point.
[0023] Preferably, the step of determining active power data varying with current at the grid connection point of the new energy power generation station according to the grid equivalent circuit comprises:
[0024] The voltage across the two ends of the current source is determined according to the current source and the voltage source, and the voltage across the two ends of the current source is:
[0025]
[0026] In the formula, is the voltage across the current source, is the equivalent reactance;
[0027] The voltage at both ends of the current source is transformed according to the imaginary part and the real part of the voltage at both ends of the current source. The voltage at both ends of the current source after the transformation is:
[0028]
[0029] The active power at the grid connection point of the new energy power generation station that changes with the current is determined according to the voltage and current at both ends of the transformed current source. The active power is:
[0030]
[0031] Where P is the active power.
[0032] Preferably, the step of determining the active power limit value according to the active power data varying with the current comprises:
[0033] The maximum active power value is determined as the active power limit value according to the active power data that varies with the current.
[0034] In a second aspect, the present invention further provides a power limit calculation device for a transmission network, comprising:
[0035] An equivalent module is used to phase-lock the voltage at the grid connection point of the new energy power station, simplify and equalize the topological structure contained in the grid connection area of the new energy power station and the flexible DC system, and obtain the grid equivalent circuit and the equivalent parameters of each equivalent structure in the grid equivalent circuit;
[0036] A power calculation module, used to determine the active power data of the grid connection point of the new energy power generation station as it changes with the current according to the grid equivalent circuit;
[0037] The power limit determination module is used to determine the active power limit value according to the active power data that varies with the current.
[0038] In a third aspect, the present invention further provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the power limit calculation method of the transmission network as described in the first aspect.
[0039] In a fourth aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed, implements the steps of the method for calculating the power limit of a transmission network as described in the first aspect.
[0040] In a fifth aspect, the present invention further provides a computer program product, comprising a computer program stored on a non-transitory computer-readable storage medium, wherein the computer program comprises program instructions, wherein when the program instructions are executed by a computer, the computer executes the steps of the method for calculating the power limit of a transmission network as described in the first aspect.
[0041] It can be seen from the above technical solutions that the present invention phase-locks the voltage at the grid connection point of the new energy power station so that the output power of the new energy power station follows the phase change of the voltage at the grid connection point of the new energy power station, thereby avoiding inaccurate calculation results due to the obvious deviation of the grid connection point voltage from the rated voltage. The topological structure contained in the grid connection area of the new energy power station and the flexible DC system is simplified and equivalent, and the active power data of the grid connection point of the new energy power station that changes with the current is determined by using an equivalent circuit, thereby determining the active power limit value, thereby improving the accuracy of the active power limit calculation, and providing effective data reference for the stable operation of the new energy power station through the flexible DC transmission system. BRIEF DESCRIPTION OF THE DRAWINGS
[0042] Figure 1 An application environment diagram of a power limit calculation method for a transmission network provided by an embodiment of the present invention;
[0043] Figure 2 A flow chart of a method for calculating a power limit of a transmission network provided by an embodiment of the present invention;
[0044] Figure 3 A schematic diagram of an equivalent circuit of a power grid provided by an embodiment of the present invention;
[0045] Figure 4 A simulation model diagram of a new energy station through a flexible DC transmission system provided in an embodiment of the present invention;
[0046] Figure 5 A simulation waveform diagram of a system in stable operation provided by an embodiment of the present invention;
[0047] Figure 6 A simulation waveform diagram of a system instability provided by an embodiment of the present invention;
[0048] Figure 7 A curve showing the change of active power outputted by a new energy station with respect to active current provided by an embodiment of the present invention;
[0049] Figure 8A schematic diagram of the structure of a power limit calculation device for a transmission network provided by an embodiment of the present invention;
[0050] Fig. 9 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION
[0051] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0052] The power limit calculation method of the transmission network provided in the embodiment of the present application can be applied to Figure 1 In the application environment shown. Among them, the transmission network system communicates with the server 102 through the network, and the transmission network system includes a new energy station, a grid-connected inverter, a transformer, an AC line, a flexible DC system and an AC system connected in sequence, wherein the flexible DC system includes a sending-end converter station, a DC line and a receiving-end converter station connected in sequence. The data storage system can store the data that the server 102 needs to process. The data storage system can be integrated on the server 102, or it can be placed on the cloud or other network servers. The server 102 can be an independent physical server, or it can be a server cluster or distributed system composed of multiple physical servers, or it can be a cloud server that provides cloud computing services.
[0053] like Figure 2 As shown, the embodiment of the present application provides a method for calculating the power limit of a transmission network, and the method is applied to Figure 1 The server 102 in the example is used as an example to illustrate the method, which includes the following steps S1 to S3. Among them:
[0054] Step S1, phase-locking the voltage at the grid connection point of the new energy power station, simplifying and equating the topological structure contained in the grid connection area of the new energy power station and the flexible DC system, and obtaining the equivalent circuit of the power grid and the equivalent parameters of each equivalent structure in the equivalent circuit of the power grid.
[0055] Among them, the new energy power generation station can be a new energy station, and the topological structure contained in the grid-connected area of the new energy power generation station and the flexible DC system includes but is not limited to the new energy station, grid-connected inverter, transformer, AC line and flexible DC system.
[0056] Equivalent parameters refer to the structural parameters after the topological structure is equivalent, such as current, voltage, etc.
[0057] It can be understood that the voltage at the grid connection point of the renewable energy power station is phase-locked so that the system tracks the voltage at the grid connection point of the renewable energy power station.
[0058] Specifically, in step S1, the voltage at the grid connection point of the new energy power station is phase-locked, and the topological structure contained in the grid connection area of the new energy power station and the flexible DC system is simplified and equivalent, including steps S101~S103.
[0059] Step S101, phase-locking the voltage at the grid connection point of the new energy power generation station, and treating the new energy power generation station as a current source according to the voltage at the grid connection point after phase locking.
[0060] Among them, taking the voltage phase at the grid connection point as a reference, the equivalent current source of the new energy power generation station changes with the voltage change at the grid connection point after phase locking.
[0061] Among them, the equivalent parameters of the current source are:
[0062]
[0063] In the formula, is the output current of the current source, I is the measured amplitude of the current at the grid connection point of the new energy power station, The angle at which the current measured at the grid connection point of a new energy power station leads the voltage measured at the grid connection point. , are respectively the active current component and reactive current component of the current source, and j is the imaginary unit; among them,
[0064]
[0065] In the formula, is the angular frequency, t is the time, The voltage measured at the grid-connected point leads the phase of the current measured at the grid-connected point.
[0066] Step S102: The flexible DC sending-end converter station in the flexible DC system is equivalent to a voltage source according to the voltage at the grid connection point after phase locking.
[0067] Among them, taking the voltage phase at the grid connection point as a reference, the equivalent voltage source of the flexible DC sending-end converter station changes with the voltage change at the grid connection point after phase locking.
[0068] Among them, the equivalent parameters of the voltage source are:
[0069]
[0070] In the formula, is the voltage of the voltage source, is the voltage amplitude measured at the flexible DC sending-end converter station, β is the angle at which the measured voltage at the flexible DC sending-end converter station lags behind the measured voltage at the new energy station grid connection point, , are the active voltage component and reactive voltage component of the voltage source respectively; among them,
[0071]
[0072] In the formula, is the angular frequency, t is the time, The voltage measured at the grid-connected point leads the phase of the current measured at the grid-connected point.
[0073] Step S103: Equivalent the connection element between the new energy power generation station and the flexible DC sending-end converter station to an equivalent reactance, and connect the current source to the voltage source through the equivalent reactance to form a loop, thereby forming an equivalent circuit of the power grid.
[0074] The connecting elements include transformers and AC lines, etc., and the current source is connected to the voltage source through an equivalent reactance to form a loop, such as Figure 3 The grid equivalent circuit is shown.
[0075] Step S2: determining active power data that changes with current at the grid connection point of the new energy power generation station according to the grid equivalent circuit.
[0076] Specifically, the process of determining the active power data of the grid connection point of the new energy power generation station according to the grid equivalent circuit in step S2 as the current changes includes steps S201 to S203. Among them:
[0077] Step S201: Determine the voltage at both ends of the current source according to the current source and the voltage source. The voltage at both ends of the current source is:
[0078]
[0079] In the formula, is the voltage across the current source, is the equivalent reactance.
[0080] Among them, the voltage of the converter station at the sending end of the new energy station is equal to the voltage at the flexible DC sending end plus the voltage on the equivalent reactance of the transformer and AC line.
[0081] Step S202: transform the voltage at both ends of the current source according to the imaginary part and the real part of the voltage at both ends of the current source. The voltage at both ends of the current source after the transformation is:
[0082]
[0083] Step S203: Determine the active power at the grid connection point of the new energy power generation station that changes with the current according to the voltage and current at both ends of the transformed current source. The active power is:
[0084]
[0085] Where P is the active power.
[0086] Among them, according to the instantaneous power theory, it can be obtained that the active power P sent by the new energy station through the flexible DC system satisfies the following relationship:
[0087]
[0088] pass The calculation method of the active power in step S203 is easy to obtain.
[0089] Step S3: determining the active power limit value according to the active power data that varies with the current.
[0090] Among them, the active power data that changes with the current can be displayed in a curve form, and the maximum active power value is determined as the active power limit value based on the active power data that changes with the current. Among them, the active power data that changes with the current within a predetermined range of the current power grid operation time can be selected to determine the maximum active power value within the predetermined range as the active power limit value of the current power grid operation time.
[0091] It should be noted that the embodiment of the present application phase-locks the voltage at the grid connection point of the new energy power station so that the output power of the new energy power station follows the phase change of the voltage at the grid connection point of the new energy power station, thereby avoiding inaccurate calculation results due to the obvious deviation of the grid connection point voltage from the rated voltage. The topological structure contained in the grid connection area of the new energy power station and the flexible DC system is simplified and equivalent, and the active power data of the grid connection point of the new energy power station that changes with the current is determined by using an equivalent circuit, thereby determining the active power limit value, thereby improving the accuracy of the active power limit calculation, and providing an effective data reference for the stable operation of the new energy power station through the flexible DC transmission system.
[0092] In PSCAD (Power Systems Computer Aided Design, electromagnetic transient simulation software) / EMTDC (Electromagnetic Transients including DC, direct current electromagnetic transient calculation program) software, build the following Figure 4The simulation model of the new energy station sent through the flexible DC system verifies the rationality of the theory. The sending-end converter station adopts island control, and the grid-connected converter of the new energy station adopts constant DC voltage and constant reactive power control. The reactive current of the new energy station is -385.4 A.
[0093] The main parameters of the simulation model are shown in Table 1:
[0094] Table 1
[0095]
[0096] In the simulation conducted in PSCAD / EMTDC, the wind speed was 7m / s 5 seconds ago, and the output active power of the new energy station was 392.663 MW. Figure 5 As shown in the figure, the wind speed increases to 7.6 m / s at 5s, and the output active power of the new energy station begins to increase. After a few seconds of fluctuation, the output active power of the new energy station stabilizes at 496 MW. Figure 6 As shown in the figure, the wind speed increases to 7.7 m / s at 5s, the active power output of the new energy station oscillates greatly, and the system becomes unstable. Figure 5 and Figure 6 According to the simulation results, the simulated value of active power limit is 496 MW.
[0097] According to the calculation method proposed in the present invention, U=188 kV, , i q =-385.4 A, let id gradually increase from 0, and draw as Figure 7 The curve of the active power of the wind farm through the flexible DC transmission system changes with the active current. Figure 7 It is known that when When the active power is 2.04 kA, the active power reaches the maximum value of 467 MW, so the calculated value of the active power limit is 467 MW, and the error with the simulated value of the active power limit is only 5.8%. It can be seen that the calculation results of the calculation method proposed in the present invention are similar to the simulation results of the international mainstream simulation software PSCAD / EMTDC, which can provide effective data reference for the stable operation of the flexible DC transmission system of the new energy station.
[0098] Based on the same inventive concept, an embodiment of the present application further provides a power limit calculation device for a power transmission network for implementing the above-mentioned power limit calculation method for a power transmission network.
[0099] The implementation solution to the problem provided by the device is similar to the implementation solution recorded in the above method, so the specific limitations in the embodiments of the power limit calculation device for one or more transmission networks provided below can refer to the limitations on the power limit calculation method for the transmission network above, and will not be repeated here.
[0100] like Figure 8 As shown, the embodiment of the present application also provides a power limit calculation device for a transmission network, comprising:
[0101] The equivalent module 100 is used to phase-lock the voltage at the grid connection point of the new energy power station, simplify and equalize the topological structure contained in the grid connection area of the new energy power station and the flexible DC system, and obtain the equivalent circuit of the power grid and the equivalent parameters of each equivalent structure in the equivalent circuit of the power grid;
[0102] The power calculation module 200 is used to determine the active power data of the grid connection point of the new energy power generation station that varies with the current according to the grid equivalent circuit;
[0103] The power limit determination module 300 is used to determine the active power limit value according to the active power data that varies with the current.
[0104] In some embodiments, the equivalent module 100 is used to phase-lock the voltage at the grid-connected point of the new energy power station, and to equate the new energy power station to a current source according to the voltage at the grid-connected point after phase-locking; to equate the flexible DC sending-end converter station in the flexible DC system to a voltage source according to the voltage at the grid-connected point after phase-locking; to equate the connecting elements between the new energy power station and the flexible DC sending-end converter station to equivalent reactance, and to connect the current source to the voltage source through the equivalent reactance to form a loop, and to form a power grid equivalent circuit.
[0105] Among them, the equivalent parameters of the current source are:
[0106]
[0107] In the formula, is the output current of the current source, I is the measured amplitude of the current at the grid connection point of the new energy power station, The angle at which the current measured at the grid connection point of a new energy power station leads the voltage measured at the grid connection point. , are respectively the active current component and reactive current component of the current source, and j is the imaginary unit; among them,
[0108]
[0109] In the formula, is the angular frequency, t is the time, The voltage measured at the grid-connected point leads the phase of the current measured at the grid-connected point.
[0110] Among them, the equivalent parameters of the voltage source are:
[0111]
[0112] In the formula, is the voltage of the voltage source, is the voltage amplitude measured at the flexible DC sending-end converter station, β is the angle at which the measured voltage at the flexible DC sending-end converter station lags behind the measured voltage at the new energy station grid connection point, , are the active voltage component and reactive voltage component of the voltage source respectively; among them,
[0113]
[0114] In the formula, is the angular frequency, t is the time, The voltage measured at the grid-connected point leads the phase of the current measured at the grid-connected point.
[0115] In some embodiments, the power calculation module 200 is used to determine the voltage across the current source according to the current source and the voltage source. The voltage across the current source is:
[0116]
[0117] In the formula, is the voltage across the current source, is the equivalent reactance;
[0118] The voltage at both ends of the current source is transformed according to the imaginary part and the real part of the voltage at both ends of the current source. The voltage at both ends of the current source after the transformation is:
[0119]
[0120] According to the voltage and current at both ends of the transformed current source, the active power at the grid connection point of the new energy power station that changes with the current is determined. The active power is:
[0121]
[0122] Where P is the active power.
[0123] In some embodiments, the power limit determination module 300 is used to determine the maximum active power value as the active power limit value according to the active power data that varies with the current.
[0124] like Fig. 9As shown, an embodiment of the present application also provides an electronic device, the electronic device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the power limit calculation method of the power transmission network in any of the above embodiments.
[0125] An embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed, the steps of the method for calculating the power limit of a transmission network as in any of the above embodiments are implemented.
[0126] An embodiment of the present application also provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, and the computer program includes program instructions, wherein when the program instructions are executed by a computer, the computer executes the steps of the power limit calculation method of the transmission network in any of the above embodiments.
[0127] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described systems, electronic devices, computer storage media and computer program products can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.
[0128] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatus.
[0129] In several embodiments provided by the present invention, it is understood that each box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and a part of a module, a program segment or a code includes one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved.
[0130] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, electronic devices, computer storage media, computer program products and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.
[0131] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
[0132] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.
[0133] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for executing all or part of the steps of the method described in each embodiment of the present invention through a computer device (which can be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (full name in English: Read-Only Memory, English abbreviation: ROM), random access memory (full name in English: Random Access Memory, English abbreviation: RAM), disk or optical disk and other media that can store program codes.
[0134] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for calculating the power limit of a transmission network, characterized in that: include: Phase-lock the voltage at the grid connection point of the new energy power station, simplify and equate the topological structure contained in the grid connection area of the new energy power station and the flexible DC system, and obtain the equivalent circuit of the power grid and the equivalent parameters of each equivalent structure in the equivalent circuit of the power grid; Determining active power data that changes with current at a grid connection point of the new energy power generation station according to the grid equivalent circuit; The active power limit value is determined based on the active power data that varies with the current.
2. The method for calculating the power limit of a transmission network according to claim 1, characterized in that: The step of phase-locking the voltage at the grid connection point of the new energy power generation station, simplifying and equilibrating the topological structure contained in the grid connection area of the new energy power generation station and the flexible DC system, and obtaining the grid equivalent circuit and the equivalent parameters of each equivalent structure in the grid equivalent circuit includes: Phase-locking the voltage at the grid connection point of the new energy power generation station, and treating the new energy power generation station as a current source according to the voltage at the grid connection point after phase locking; The flexible DC sending-end converter station in the flexible DC system is equivalent to a voltage source according to the voltage at the grid connection point after phase locking; The connecting element between the new energy power generation station and the flexible DC sending-end converter station is equivalent to an equivalent reactance, and the current source is connected to the voltage source through the equivalent reactance to form a loop, thereby forming an equivalent circuit of a power grid.
3. The method for calculating the power limit of a transmission network according to claim 2, characterized in that: The equivalent parameters of the current source are: In the formula, is the output current of the current source, I is the measured amplitude of the current at the grid connection point of the new energy power station, The angle at which the current measured at the grid connection point of a new energy power station leads the voltage measured at the grid connection point. , are respectively the active current component and reactive current component of the current source, and j is the imaginary unit; among them, In the formula, is the angular frequency, t is the time, The voltage measured at the grid-connected point leads the phase of the current measured at the grid-connected point.
4. The method for calculating the power limit of a transmission network according to claim 2, characterized in that: The equivalent parameters of the voltage source are: In the formula, is the voltage of the voltage source, is the voltage amplitude measured at the flexible DC sending-end converter station, β is the angle at which the measured voltage at the flexible DC sending-end converter station lags behind the measured voltage at the new energy station grid connection point, , are the active voltage component and reactive voltage component of the voltage source respectively; among them, In the formula, is the angular frequency, t is the time, The voltage measured at the grid-connected point leads the phase of the current measured at the grid-connected point.
5. The method for calculating the power limit of a transmission network according to claim 2, characterized in that: The step of determining the active power data varying with the current at the grid connection point of the new energy power generation station according to the grid equivalent circuit comprises: The voltage across the two ends of the current source is determined according to the current source and the voltage source, and the voltage across the two ends of the current source is: In the formula, is the voltage across the current source, is the equivalent reactance; The voltage at both ends of the current source is transformed according to the imaginary part and the real part of the voltage at both ends of the current source. The voltage at both ends of the current source after the transformation is: The active power at the grid connection point of the new energy power generation station that changes with the current is determined according to the voltage and current at both ends of the transformed current source. The active power is: Where P is the active power.
6. The method for calculating the power limit of a transmission network according to claim 1, characterized in that: The step of determining the active power limit value according to the active power data varying with the current comprises: The maximum active power value is determined as the active power limit value according to the active power data that varies with the current.
7. A power limit calculation device for a transmission network, characterized in that: include: An equivalent module is used to phase-lock the voltage at the grid connection point of the new energy power station, simplify and equalize the topological structure contained in the grid connection area of the new energy power station and the flexible DC system, and obtain the grid equivalent circuit and the equivalent parameters of each equivalent structure in the grid equivalent circuit; A power calculation module, used to determine the active power data of the grid connection point of the new energy power generation station as it changes with the current according to the grid equivalent circuit; The power limit determination module is used to determine the active power limit value according to the active power data that varies with the current.
8. An electronic device, characterized in that: The electronic device includes a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the processor executes the steps of the method for calculating the power limit of a power transmission network as claimed in any one of claims 1 to 6.
9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed, the steps of the method for calculating the power limit of a power transmission network according to any one of claims 1 to 6 are implemented.
10. A computer program product, characterized in that The computer program product comprises a computer program stored on a non-transitory computer-readable storage medium, wherein the computer program comprises program instructions, wherein when the program instructions are executed by a computer, the computer is caused to perform the steps of the method for calculating the power limit of a transmission network as claimed in any one of claims 1 to 6.