New energy ac-dc hybrid dynamic platform supporting multiple types of dc power transmission

Abstract

The utility model discloses a new energy ac-dc hybrid dynamic model platform of supporting multiple types of direct current transmission belongs to dynamic model experiment technical field. In the new energy ac-dc hybrid dynamic model platform of supporting multiple types of direct current transmission, the power grid simulation system includes power grid simulator, adopts full four quadrant feedback type framework, the AC simulation system includes superior line simulation unit, static var generator branch, synchronous machine branch and inferior line simulation unit, and inferior line simulation unit connects new energy simulation unit, and its built-in multiple parallel general grid-connected inverter is configured with open hardware burning interface, and adjustable tap inductance is arranged in superior line simulation unit and inferior line simulation unit, and the direct current transmission system includes the conventional direct current conversion unit and the flexible direct current conversion unit of selective connection through switch unit, and constructs at least two different types of direct current transmission topology. The utility model realizes the fine simulation of complex AC power grid characteristic and the flexible reconstruction of multiple types of direct current transmission topology.

Description

Technical Field

[0001] This utility model belongs to the field of dynamic model experimental technology, specifically relating to a new energy AC / DC hybrid dynamic model platform that supports multiple types of DC power transmission. Background Technology

[0002] The statements herein provide only background information related to this invention and do not necessarily constitute prior art.

[0003] With the advancement of the "dual carbon" target, the proportion of new energy power generation, represented by wind power and photovoltaics, continues to increase. New power systems are exhibiting new characteristics such as a high proportion of power electronic devices, low system inertia, and prominent broadband oscillation risks. To study the operating characteristics and control strategies of large-scale new energy transmission through AC / DC hybrid power grids, dynamic model experimental platforms have become an important verification method.

[0004] Existing dynamic model experimental platforms have the following main shortcomings in supporting research on novel power systems:

[0005] First, the AC side lacks multi-machine interaction and impedance simulation capabilities. Traditional platforms mostly adopt simple parallel structures, lacking multi-machine refined simulation cabinets and layered line impedance simulation designs, and usually do not have open hardware programming interfaces, making it difficult to reproduce the complex dynamic characteristics under high proportion of new energy access and wide range of grid strength adaptability experiments.

[0006] Second, the DC transmission system suffers from limited configuration and lacks topology reconfiguration capabilities. Most existing platforms are not equipped with LCC and MMC converters, or only support a single fixed topology. They cannot achieve multiple combination modes of LCC and MMC through hardware switching, making it difficult to simulate the complex operating scenario of high proportion of new energy being transmitted via AC / DC hybrid interconnection.

[0007] Therefore, existing dynamic model experimental platforms still have significant shortcomings in terms of refined simulation on the AC side and flexible topology reconstruction on the DC side, which greatly restricts the dynamic model experimental research capabilities of high-proportion new energy AC / DC hybrid systems. Utility Model Content

[0008] The purpose of this invention is to provide a new energy AC / DC hybrid dynamic simulation platform that supports multiple types of DC power transmission, in order to solve the shortcomings of existing dynamic simulation platforms in terms of lack of AC multi-machine interaction and impedance simulation capabilities, single configuration of DC power transmission systems, and lack of topology reconfiguration capabilities.

[0009] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0010] The technical solution of this utility model provides a new energy AC / DC hybrid simulation platform that supports multiple types of DC power transmission, including: a power grid simulation system, an AC simulation system, and a DC transmission system;

[0011] The power grid simulation system includes a power grid simulator, which adopts a full four-quadrant feedback architecture;

[0012] The AC simulation system includes an upper-level line simulation unit and multiple branch units connected to the upper-level line simulation unit; the multiple branch units include a static var generator branch, a synchro branch, and at least one lower-level line simulation unit.

[0013] Each lower-level line simulation unit is connected to a new energy simulation unit; the new energy simulation unit includes multiple parallel universal grid-connected inverters and is equipped with an open hardware programming interface.

[0014] Both the upper-level and lower-level line simulation units are equipped with adjustable tapped inductors for simulating collector line impedance under different short-circuit ratios.

[0015] The DC transmission system includes independent conventional DC LCC converter units and flexible DC MMC converter units, which are selectively connected through switching units to construct at least two different types of DC transmission topologies.

[0016] In at least one embodiment, the power grid simulator is configured in power supply mode, specifically: the power grid simulator is connected to the bus of the AC simulation system as a power source.

[0017] In at least one embodiment, the power grid simulator is configured in load mode, specifically: the power grid simulator is connected to the receiving end of the DC transmission system as a load.

[0018] In at least one embodiment, the power grid simulation system further includes a main transformer simulation cabinet connected to the power grid simulator, wherein an isolation transformer is configured inside the main transformer simulation cabinet.

[0019] In at least one embodiment, a cascaded enhanced SVG is configured in the static var generator branch.

[0020] In at least one embodiment, the synchronous machine branch is connected to an electrically excited synchronous generator set; the electrically excited synchronous generator set is equipped with a prime mover simulation device.

[0021] In at least one embodiment, the adjustable tap inductor is composed of multiple inductor coils connected in series and has multiple tap terminals, and the inductance value is adjusted by changing the position of the access terminals.

[0022] In at least one embodiment, the different types of DC transmission topologies specifically include four DC transmission topologies: LCC-LCC, MMC-MMC, LCC-MMC, and MMC-LCC.

[0023] In at least one embodiment, the DC transmission system further includes a DC line simulation unit and an AC line simulation unit, which are used to simulate the impedance characteristics of the DC transmission line and the near-field AC line, respectively.

[0024] In at least one embodiment, both the DC line simulation unit and the AC line simulation unit are equipped with multi-tap adjustable inductors, and the impedance characteristics of DC lines of different lengths are simulated by switching the tap inductance values.

[0025] The beneficial effects of the above-described technical solution of this utility model are as follows:

[0026] (1) The new energy AC / DC hybrid linkage model platform supporting multiple types of DC power transmission of this utility model can realistically reproduce the multi-machine coupling oscillation characteristics of high-proportion new energy power plants through the design of layered line simulation units and new energy multi-machine parallel structure, and supports wide-range short-circuit ratio adaptability experiments from strong power grid to extremely weak power grid. The combined use of the upper-level line simulation unit and the lower-level line simulation unit can accurately simulate the impedance characteristics of collector lines at different voltage levels.

[0027] (2) The new energy AC / DC hybrid linkage platform supporting multiple types of DC power transmission of this utility model can realize full parameter programmable adjustment of voltage, frequency and impedance and load mode reuse through the full four-quadrant feedback grid simulator. It can simulate various typical faults and extreme working conditions such as low voltage ride-through and frequency fluctuation, and has energy feedback function, which is energy-saving and environmentally friendly.

[0028] (3) The new energy AC / DC hybrid linkage module platform supporting multiple types of DC power transmission supports the rapid implantation of user-defined control modules and hardware-in-the-loop testing. It can be used to study the coupling oscillation characteristics and collaborative control strategies of multiple inverters in parallel operation, providing a convenient way for the research and development and verification of new grid-connected control strategies.

[0029] (4) The new energy AC / DC hybrid linkage module platform supporting multiple types of DC power transmission can flexibly construct multiple DC power transmission topologies on the same physical platform through the design of independent LCC / MMC converter units and switching units, including pure conventional DC, pure flexible DC and hybrid DC and other combination modes, providing a hardware foundation for comparative research on different technical routes, and facilitating the verification of system interaction characteristics and control coordination under multiple DC topology combinations.

[0030] (5) The new energy AC / DC hybrid linkage module platform that supports multiple types of DC power transmission constructs a real physical experimental environment for the multi-dimensional dynamic characteristics of AC / DC hybrid systems with a high proportion of power electronic equipment by integrating and coordinating the new energy inverter, synchronous generator, SVG and DC power transmission system on the same platform. This can fully verify the feasibility of the system-level control strategy. Attached Figure Description

[0031] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0032] Figure 1 This is a schematic diagram of the system electrical topology of the new energy AC / DC hybrid linkage platform supporting multiple types of DC power transmission disclosed in Embodiment 1 of this utility model;

[0033] Figure 2 This is a schematic diagram of the internal structure of the adjustable tap inductor disclosed in Embodiment 1 of this utility model.

[0034] The distances or dimensions between parts have been exaggerated to show their positions; the diagram is for illustrative purposes only. Detailed Implementation

[0035] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0036] For ease of description, the words "up," "down," "left," and "right" appearing in this utility model only indicate that they are consistent with the up, down, left, and right directions of the accompanying drawings. They do not limit the structure and are merely for the purpose of facilitating the description of this utility model and simplifying the description. They do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0037] Terminology Explanation: The terms "installation," "connection," "linking," and "fixing" in this utility model should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction relationship between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0038] As described in the background section, the purpose of this invention is to provide a new energy AC / DC hybrid dynamic simulation platform that supports multiple types of DC power transmission, in order to solve the shortcomings of existing dynamic simulation platforms in terms of lack of AC multi-machine interaction and impedance simulation capabilities, single configuration of DC power transmission systems, and lack of topology reconfiguration capabilities.

[0039] Example 1

[0040] In a typical embodiment of this utility model, such as Figure 1 and Figure 2 As shown in the figure, this embodiment discloses a new energy AC / DC hybrid linkage model platform that supports multiple types of DC power transmission, which mainly includes three core modules: a power grid simulation system, an AC simulation system, and a DC transmission system.

[0041] In this embodiment, the power grid simulation system includes a power grid simulator. The power grid simulator adopts a full four-quadrant feedback architecture and has bidirectional configuration capabilities: it can be configured as a power supply mode, outputting programmable voltage and frequency to simulate different power grid operating conditions; it can also be configured as a load mode, acting as a full four-quadrant electronic load to absorb system power and simulate the characteristics of the receiving-end power grid or load. Through the full four-quadrant feedback power grid simulator, programmable adjustment of all parameters of voltage, frequency, and impedance, as well as load mode reuse, can be achieved. It can simulate various typical faults and extreme operating conditions such as low voltage ride-through and frequency fluctuations, while also possessing energy feedback functionality, thus saving energy and protecting the environment.

[0042] As a further implementation, the power grid simulation system also includes a main transformer simulation cabinet connected to the power grid simulator. This cabinet contains an isolation transformer. When a short circuit or other fault occurs within the platform, the isolation transformer can limit the fault current, preventing it from spreading to the upstream power source, thus achieving electrical isolation and simulating the physical characteristics of an actual grid-connected transformer. As a further implementation, the isolation transformer built into the main transformer simulation cabinet uses a 1:1 turns ratio isolation transformer for electrical isolation, protecting personnel and equipment and enhancing reliability.

[0043] Considering that traditional dynamic simulation test platforms struggle to achieve full-element hybrid access of new energy inverters, synchronous generators, SVG, and DC transmission systems within a single system, which limits the multi-dimensional dynamic characteristic analysis of AC / DC hybrid systems containing a high proportion of power electronic equipment, this embodiment includes an upper-level line simulation unit and multiple branch units connected to the upper-level line simulation unit. As an example, such as... Figure 1 As shown, the upper-level line simulation unit is an upper-level line simulation cabinet, which contains bus I. Bus I is connected to a grid switch to lead out four branch units. The four branch units include a static var generator branch, a synchronous machine branch, and two lower-level line simulation units. As an optional implementation, the number of branch units can be expanded according to actual needs.

[0044] As a further implementation, a cascaded enhanced SVG is configured in the static var generator branch (SVG branch) to provide dynamic reactive power support and impedance reshaping control, which can effectively suppress broadband oscillations.

[0045] In the synchronous machine branch, an electrically excited synchronous generator set is connected. This electrically excited synchronous generator set is equipped with a prime mover simulation device, which can be flexibly configured to simulate the generator mode of a conventional generator set or to provide reactive power support and rotational inertia in the mode of a synchronous condenser.

[0046] Each lower-level line simulation unit is connected to a new energy simulation unit. As an example, the lower-level line simulation unit can be a lower-level line simulation cabinet, used to simulate the impedance characteristics of the internal collector lines of a wind farm or photovoltaic power station. The new energy simulation unit is a four-unit new energy simulation cabinet, containing four universal grid-connected inverters connected in parallel via independent branches. Each universal grid-connected inverter is equipped with an open hardware programming interface, supporting the rapid implantation of user-defined control modules and hardware-in-the-loop testing. This can be used to study the coupling oscillation characteristics and collaborative control strategies of multiple inverters operating in parallel, providing a convenient way for the research and verification of new grid-connected control strategies.

[0047] In this embodiment, both the upper-level and lower-level line simulation units integrate adjustable tapped inductors to simulate the collector line impedance under different short-circuit ratios. For example... Figure 2 As shown, the adjustable tap inductor consists of four inductor coils connected in series, each with a fixed inductance of 0.5mH. Five taps, Tap1 to Tap5, are led out from the two ends and the middle connection point of the inductor coils. The inflow and outflow ends of the circuit can be arbitrarily connected to different taps. By changing the tap positions connected to the inflow and outflow ends, the number of turns of the inductor coil connected to the circuit can be adjusted, thereby changing the inductance value. For example, when both the inflow and outflow ends are connected to Tap1, the inductance is 0mH; when the inflow end is connected to Tap1 and the outflow end is connected to Tap5, all four inductor coils are connected, and the total inductance is 2.0mH. This tiered adjustment method can accurately simulate different short-circuit ratio conditions from strong to extremely weak power grids, as well as the impedance characteristics of lines of different lengths.

[0048] By designing a hierarchical line simulation unit and a multi-unit parallel structure for new energy power plants, the multi-unit coupled oscillation characteristics of high-proportion new energy power plants can be realistically reproduced, and wide-range short-circuit ratio adaptability experiments from strong grids to extremely weak grids can be supported. The combined use of upper-level and lower-level line simulation units can accurately simulate the collector line impedance characteristics at different voltage levels.

[0049] The DC transmission system provides flexible DC topology reconfiguration capabilities. This system includes independent conventional DC LCC converter units and flexible DC MMC converter units. These units are not fixedly connected but selectively connected via switching units to construct at least two different types of DC transmission topologies. As an example, the conventional DC LCC converter unit can be a conventional DC LCC converter cabinet, the flexible DC MMC converter unit can be a flexible DC MMC converter cabinet, and the switching unit can be a switch matrix. The conventional DC LCC converter cabinet and the flexible DC MMC converter cabinet are physically reconfigured through the switch matrix. By switching the on / off states of the switches in the switch matrix, various DC transmission topologies can be flexibly constructed, including but not limited to LCC-LCC, MMC-MMC, LCC-MMC, and MMC-LCC DC transmission topologies. By designing independent LCC / MMC converter units and switching units, various DC transmission topologies can be flexibly constructed on the same physical platform, including pure conventional DC, pure flexible DC, and hybrid DC, providing a hardware foundation for comparative studies of different technical routes and facilitating the verification of system interaction characteristics and control coordination under various DC topology combinations.

[0050] As a further embodiment, the DC transmission system also includes a DC line simulation unit and an AC line simulation unit, used to simulate the impedance characteristics of the DC transmission line and the near-field AC line, respectively. As an example, the DC line simulation unit can be a DC line simulation cabinet, and the AC line simulation unit can be an AC line simulation cabinet. Both the DC line simulation unit and the AC line simulation unit are equipped with... Figure 2 The multi-tap adjustable inductor shown can simulate the impedance characteristics of DC lines of different lengths by switching the tap inductance values.

[0051] In this embodiment, the power grid simulator can be selectively connected to either the AC simulation system or the DC transmission system. Specifically, it is connected to bus I of the AC simulation system and the receiving end of the DC transmission system via contactors or circuit breakers, respectively. When the power grid simulator is connected to bus I, it serves as the power source for the AC simulation system, providing a programmable grid voltage to the entire AC side. When the power grid simulator is connected to the receiving end of the DC transmission system, it operates in load mode, simulating the characteristics of the receiving end grid or load, absorbing power from the DC system, and realizing bidirectional power flow and energy feedback.

[0052] This embodiment of the new energy AC / DC hybrid linkage module platform supporting multiple types of DC power transmission constructs a real physical experimental environment for the multi-dimensional dynamic characteristics of AC / DC hybrid systems with a high proportion of power electronic devices by integrating and coordinating new energy inverters, synchronous generators, SVG and DC power transmission systems on the same platform. This allows for comprehensive verification of the feasibility of system-level control strategies.

[0053] The new energy AC / DC hybrid transmission platform supporting multiple types of DC power transmission in this embodiment can achieve the following experimental verifications through existing software and hardware control:

[0054] (1) Basic characteristics test of new energy grid connection: Using the programming function of the grid simulator, the grid fault conditions such as voltage fault ride-through, frequency fluctuation and harmonic injection can be simulated to verify the grid connection adaptability and fault response capability of new energy inverters in extreme environments.

[0055] (2) Multi-machine coupling oscillation suppression test: Using the four-machine parallel structure of the new energy simulation unit and the layered impedance design of the adjustable inductor, the multi-machine broadband oscillation phenomenon of high-proportion new energy power stations is reproduced to verify the effectiveness of oscillation suppression strategies such as SVG impedance reshaping and virtual synchronous machine control.

[0056] (3) Open control strategy verification test: Relying on the open hardware programming interface of the general grid-connected inverter, it supports the rapid implantation of user-defined control algorithms and hardware-in-the-loop testing to verify the feasibility of the new grid-connected control strategy.

[0057] (4) DC transmission base operation test: By switching the state of the switch unit, an independent LCC or MMC DC transmission system can be constructed to simulate the impedance of different line lengths and verify the steady-state operation characteristics, start-stop control and fault protection logic of conventional DC and flexible DC systems.

[0058] (5) Hybrid DC topology reconfiguration test: By flexibly switching the switching matrix, the LCC-MMC hybrid DC transmission scenario simulation is realized, and the system interaction characteristics, power coordination control and fault ride-through strategies under various DC topology combinations are verified.

[0059] (6) New energy transmission via DC system-level test: The new energy cluster of the AC simulation system is connected to the DC transmission system to simulate the full working conditions of the Shagohuang large base via DC transmission, and to verify the overall stability, transient response characteristics and coordinated control strategy of the AC-DC hybrid system.

[0060] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A new energy AC / DC hybrid transmission platform supporting multiple types of DC power transmission, characterized in that: include: Power grid simulation system, AC simulation system and DC transmission system; The power grid simulation system includes a power grid simulator, which adopts a full four-quadrant feedback architecture; The AC simulation system includes an upper-level line simulation unit and multiple branch units connected to the upper-level line simulation unit; the multiple branch units include a static var generator branch, a synchro branch, and at least one lower-level line simulation unit. Each lower-level line simulation unit is connected to a new energy simulation unit; the new energy simulation unit includes multiple parallel universal grid-connected inverters and is equipped with an open hardware programming interface. Both the upper-level and lower-level line simulation units are equipped with adjustable tapped inductors for simulating collector line impedance under different short-circuit ratios. The DC transmission system includes independent conventional DC LCC converter units and flexible DC MMC converter units, which are selectively connected through switching units to construct at least two different types of DC transmission topologies.

2. The new energy AC / DC hybrid transmission platform supporting multiple types of DC power transmission as described in claim 1, characterized in that, The power grid simulator is configured in power supply mode, specifically: the power grid simulator is connected to the bus of the AC simulation system as a power source.

3. The new energy AC / DC hybrid transmission platform supporting multiple types of DC power transmission as described in claim 1, characterized in that, The power grid simulator is configured in load mode, specifically: the power grid simulator is connected to the receiving end of the DC transmission system as a load.

4. The new energy AC / DC hybrid transmission platform supporting multiple types of DC power transmission as described in claim 1, characterized in that, The power grid simulation system also includes a main transformer simulation cabinet connected to the power grid simulator, which contains an isolation transformer.

5. The new energy AC / DC hybrid transmission platform supporting multiple types of DC power transmission as described in claim 1, characterized in that, The static var generator branch is equipped with a cascaded enhanced SVG.

6. The new energy AC / DC hybrid transmission platform supporting multiple types of DC power transmission as described in claim 1, characterized in that, The synchronous machine branch is connected to the electrically excited synchronous generator set; the electrically excited synchronous generator set is equipped with a prime mover simulation device.

7. The new energy AC / DC hybrid transmission platform supporting multiple types of DC power transmission as described in claim 1, characterized in that, An adjustable tap inductor consists of multiple inductor coils connected in series and has multiple tap terminals. The inductance value can be adjusted by changing the position of the connected terminals.

8. The new energy AC / DC hybrid transmission platform supporting multiple types of DC power transmission as described in claim 1, characterized in that, The different types of DC transmission topologies specifically include four types: LCC-LCC, MMC-MMC, LCC-MMC, and MMC-LCC.

9. The new energy AC / DC hybrid transmission platform supporting multiple types of DC power transmission as described in claim 1, characterized in that, The DC transmission system also includes a DC line simulation unit and an AC line simulation unit, which are used to simulate the impedance characteristics of DC transmission lines and near-area AC lines, respectively.

10. The new energy AC / DC hybrid transmission platform supporting multiple types of DC power transmission as described in claim 9, characterized in that, Both the DC line simulation unit and the AC line simulation unit are equipped with multi-tap adjustable inductors, which can simulate the impedance characteristics of DC lines of different lengths by switching the tap inductance values.

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