A hybrid electromechanical-electromagnetic simulation method and device based on hybrid DC system

Abstract

The present invention discloses an electromechanical-electromagnetic hybrid simulation method and device based on a hybrid DC system. The method obtains basic parameters of a simulation network containing a parallel hybrid DC system. Based on simulation requirements, the simulation network is divided to obtain an electromagnetic transient subsystem, an electromechanical transient subsystem, and hybrid simulation interface locations, which are then modeled to generate an electromagnetic transient model, an electromechanical transient model, and an interface model. These multiple models are then spliced ​​together to form a first electromechanical-electromagnetic hybrid simulation model. Based on the obtained basic parameters, the first electromechanical-electromagnetic hybrid simulation model is optimized to generate a second electromechanical-electromagnetic hybrid simulation model for simulating the power grid to be simulated. Compared to existing technologies, the present invention partially utilizes electromagnetic transient simulation in addition to electromechanical transient simulation to achieve electromechanical-electromagnetic transient hybrid simulation calculations, improving simulation accuracy and facilitating accurate and rapid simulation analysis of large power grids.

Description

Technical Field

[0001] The present invention relates to the technical field of power system simulation and control, and in particular to an electromechanical-electromagnetic hybrid simulation method and device based on a hybrid direct current system. Background Art

[0002] Currently, HVDC systems, characterized by large transmission capacity, high voltage levels, and long transmission distances, have been widely used in my country. However, these systems are prone to commutation failures, resulting in power interruptions and impacting the safe and stable operation of the receiving grid. Furthermore, with the increasing number of UHV and ultra-large capacity DC transmission feed-in points, the problem of simultaneous commutation failures on multiple DC lines has become more prominent. In recent years, flexible DC transmission technology based on fully controlled devices has rapidly developed in my country due to its advantages of good controllability, flexible operation, and strong adaptability. Hybrid DC systems combine the advantages of conventional and flexible DC systems. Using flexible DC transmission at the receiving end avoids commutation failures and improves controller flexibility, making them an important development direction for future HVDC transmission in my country.

[0003] The construction and commissioning of large-capacity hybrid DC transmission projects have placed higher demands on large-scale power grid simulation capabilities. Traditional electromechanical transient simulation uses quasi-steady-state models, which cannot accurately simulate the dynamic characteristics of converter valves. Electromagnetic transient simulation, due to its complex models and small computational step sizes, is difficult to achieve rapid simulation of large-scale power grids, resulting in low simulation efficiency. Therefore, single electromechanical transient simulation and electromagnetic transient simulation cannot effectively meet the simulation speed and accuracy requirements of large-scale power grids. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an electromechanical-electromagnetic hybrid simulation method and device based on a hybrid DC system. On the basis of electromechanical transient simulation, electromagnetic transient simulation is partially adopted to realize electromechanical-electromagnetic transient hybrid simulation calculation, thereby improving the simulation accuracy and facilitating accurate and rapid simulation analysis of large power grids.

[0005] In order to solve the above technical problems, the present invention provides an electromechanical-electromagnetic hybrid simulation method and device based on a hybrid DC system, comprising:

[0006] Obtain basic parameters of the simulation network containing the parallel hybrid DC system;

[0007] According to simulation requirements, the simulation network is divided to obtain an electromagnetic transient subsystem and an electromechanical transient subsystem, and a hybrid simulation interface position is selected;

[0008] Modeling the electromagnetic transient subsystem, the electromechanical transient subsystem, and the hybrid simulation interface position to generate an electromagnetic transient model, an electromechanical transient model, and an interface model, and splicing the electromagnetic transient model and the electromechanical transient model through the interface model to form a first electromechanical-electromagnetic hybrid simulation model;

[0009] The first electromechanical-electromagnetic hybrid simulation model is optimized according to the obtained basic parameters to generate a second electromechanical-electromagnetic hybrid simulation model; and simulation calculations are performed on the power grid to be simulated using the second electromechanical-electromagnetic hybrid simulation model.

[0010] Furthermore, the basic parameters of the simulation network containing the parallel hybrid DC system are obtained, specifically:

[0011] Obtaining the topological structure of each parallel hybrid DC system in the simulation network, and simultaneously obtaining the grid structure parameters, technical parameters, and operating parameters of the simulation network;

[0012] The grid structure parameters include the number of parallel hybrid DC systems, the number of LCC converter stations and the number of VSC converter stations contained in each parallel hybrid DC system;

[0013] The technical parameters include parameters of each parallel hybrid DC system and technical parameters of the AC network;

[0014] The operating parameters include the arranged active power, reactive power, AC voltage and current, DC voltage and current, converter tap position, filter activation and deactivation status, and the command value, control mode, and selected balancing station of each converter station in each parallel hybrid DC system.

[0015] Furthermore, according to the simulation requirements, the simulation network is divided to obtain the electromagnetic transient subsystem and the electromechanical transient subsystem, and the hybrid simulation interface position is selected, specifically:

[0016] According to the simulation requirements, the simulation network containing the parallel hybrid DC system is divided into a network so that the simulation network divides the traditional AC power grid into an electromechanical transient subsystem and the parallel hybrid DC system into an electromagnetic transient subsystem, and the position of the hybrid simulation interface is set.

[0017] Furthermore, the first electromechanical-electromagnetic hybrid simulation model is optimized, specifically:

[0018] Performing DC initialization adjustment and model verification on the first electromechanical-electromagnetic hybrid simulation model;

[0019] By reading and adjusting the converter tap information of the LCC converter station according to the power flow data, so that the variables of the LCC converter station in the electromagnetic transient model are consistent with the power flow data;

[0020] The operating parameters of the VSC converter station are read and set according to the power flow calculation results, and the consistency of the data of the electromechanical transient model and the data of the electromagnetic transient model is verified to obtain the electromechanical-electromagnetic hybrid simulation data of stable operation.

[0021] Furthermore, the electromagnetic transient subsystem, the electromechanical transient subsystem and the hybrid simulation interface position are modeled to generate an electromagnetic transient model, an electromechanical transient model and an interface model, specifically:

[0022] Build the model of each component in the electromechanical transient network based on the electromechanical transient program, and form and establish the electromechanical transient model based on the corresponding electromechanical data file;

[0023] Based on the electromagnetic transient program, a model of each component in the electromagnetic transient network including the parallel hybrid DC system is constructed, and an electromagnetic transient model is established based on the corresponding electromagnetic data file;

[0024] According to the interface position, the interface data is constructed, and based on the PSD-PSMODEL simulation program, the interface model of the electromechanical transient subsystem is established, and the interface model of the electromagnetic transient subsystem is also established.

[0025] Furthermore, the present invention also provides an electromechanical-electromagnetic hybrid simulation device based on a hybrid DC system, comprising: an acquisition module, a network division module, a model splicing module and a model optimization module;

[0026] The acquisition module is used to obtain basic parameters of a simulation network containing a parallel hybrid DC system;

[0027] The network partitioning module is used to partition the simulation network according to simulation requirements to obtain an electromagnetic transient subsystem and an electromechanical transient subsystem, and simultaneously select a hybrid simulation interface position;

[0028] The model splicing module is used to model the electromagnetic transient subsystem, the electromechanical transient subsystem and the hybrid simulation interface position to generate an electromagnetic transient model, an electromechanical transient model and an interface model, and splice the electromagnetic transient model and the electromechanical transient model through the interface model to form a first electromechanical-electromagnetic hybrid simulation model;

[0029] The model optimization module is used to optimize the first electromechanical-electromagnetic hybrid simulation model according to the obtained basic parameters to generate a second electromechanical-electromagnetic hybrid simulation model; and perform simulation calculations on the power grid to be simulated through the second electromechanical-electromagnetic hybrid simulation model.

[0030] Furthermore, the acquisition module is used to obtain basic parameters of the simulation network containing the parallel hybrid DC system, specifically:

[0031] Obtaining the topological structure of each parallel hybrid DC system in the simulation network, and simultaneously obtaining the grid structure parameters, technical parameters, and operating parameters of the simulation network;

[0032] The grid structure parameters include the number of parallel hybrid DC systems, the number of LCC converter stations and the number of VSC converter stations contained in each parallel hybrid DC system;

[0033] The technical parameters include parameters of each parallel hybrid DC system and technical parameters of the AC network;

[0034] The operating parameters include the arranged active power, reactive power, AC voltage and current, DC voltage and current, converter tap position, filter activation and deactivation status, and the command value, control mode, and selected balancing station of each converter station in each parallel hybrid DC system.

[0035] Furthermore, the network partitioning module is used to partition the simulation network according to simulation requirements to obtain an electromagnetic transient subsystem and an electromechanical transient subsystem, and select the location of the hybrid simulation interface, specifically:

[0036] According to the simulation requirements, the simulation network containing the parallel hybrid DC system is divided into a network so that the simulation network divides the traditional AC power grid into an electromechanical transient subsystem and the parallel hybrid DC system into an electromagnetic transient subsystem, and the position of the hybrid simulation interface is set.

[0037] Furthermore, the model optimization module is used to optimize the first electromechanical-electromagnetic hybrid simulation model, specifically:

[0038] Performing DC initialization adjustment and model verification on the first electromechanical-electromagnetic hybrid simulation model;

[0039] By reading and adjusting the converter tap information of the LCC converter station according to the power flow data, so that the variables of the LCC converter station in the electromagnetic transient model are consistent with the power flow data;

[0040] The operating parameters of the VSC converter station are read and set according to the power flow calculation results, and the consistency of the data of the electromechanical transient model and the data of the electromagnetic transient model is verified to obtain the electromechanical-electromagnetic hybrid simulation data of stable operation.

[0041] Furthermore, the model splicing module is used to model the electromagnetic transient subsystem, the electromechanical transient subsystem and the hybrid simulation interface position to generate an electromagnetic transient model, an electromechanical transient model and an interface model, specifically:

[0042] Build the model of each component in the electromechanical transient network based on the electromechanical transient program, and form and establish the electromechanical transient model based on the corresponding electromechanical data file;

[0043] Based on the electromagnetic transient program, a model of each component in the electromagnetic transient network including the parallel hybrid DC system is constructed, and an electromagnetic transient model is established based on the corresponding electromagnetic data file;

[0044] According to the interface position, the interface data is constructed, and based on the PSD-PSMODEL simulation program, the interface model of the electromechanical transient subsystem is established, and the interface model of the electromagnetic transient subsystem is also established.

[0045] The electromechanical-electromagnetic hybrid simulation method and device based on a hybrid DC system according to the embodiment of the present invention have the following beneficial effects compared with the prior art:

[0046] By first obtaining the basic parameters of a simulation network containing a parallel hybrid DC system, the simulation network is divided according to simulation requirements, so that the present invention only includes an electromechanical transient subsystem, an electromagnetic transient subsystem, and an interface, forming a "one-to-one" interface mode. At the same time, based on the obtained basic parameters of the simulation network, each divided part is modeled to generate an electromagnetic transient model, an electromechanical transient model, and an interface model. The electromagnetic transient model and the electromechanical transient model are then spliced ​​together through the interface model to generate a second electromechanical-electromagnetic hybrid simulation model for simulating the power grid. Compared with the existing technology, the present invention partially adopts electromagnetic transient simulation on the basis of electromechanical transient simulation for the parallel type, realizes electromechanical-electromagnetic transient hybrid simulation calculation, improves simulation accuracy, and facilitates accurate and rapid simulation analysis of large power grids. It has important engineering application value for subsequent large power grid power system dynamic characteristic mechanism analysis, power system security and stability analysis, and large power grid fault inversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a flow chart of an embodiment of an electromechanical-electromagnetic hybrid simulation method based on a hybrid DC system provided by the present invention;

[0048] Figure 2 This is a structural diagram of an embodiment of an electromechanical-electromagnetic hybrid simulation device based on a hybrid DC system provided by the present invention;

[0049] Figure 3 1. A schematic diagram of the topological structure of a parallel hybrid DC system according to an embodiment of an electromechanical-electromagnetic hybrid simulation method and apparatus based on a hybrid DC system provided by the present invention;

[0050] Figure 4 It is a schematic diagram of the topological structure of a parallel hybrid DC system according to an embodiment of an electromechanical-electromagnetic hybrid simulation method and device based on a hybrid DC system provided by the present invention. DETAILED DESCRIPTION

[0051] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making any creative efforts shall fall within the scope of protection of the present invention.

[0052] Example 1

[0053] See also Figure 1 , Figure 1 FIG. 1 is a flow chart of an embodiment of an electromechanical-electromagnetic hybrid simulation method based on a hybrid DC system provided by the present invention. Figure 1 As shown, the method includes steps 101 to 104, which are specifically as follows:

[0054] Step 101: Obtain basic parameters of a simulation network containing a parallel hybrid DC system.

[0055] In this embodiment, the topology of each parallel hybrid DC system in the simulation network is obtained, and the grid structure parameters, technical parameters and operating parameters of the simulation network are obtained at the same time. The topology of the parallel hybrid DC system is as follows: Figure 3 shown.

[0056] In this embodiment, the grid structure parameters of the simulation network include the number of parallel hybrid DC systems, the number of LCC converter stations and the number of VSC converter stations contained in each parallel hybrid DC system, and the LCC converter stations are respectively denoted as S Lcc1 , S Lcc2 ,…,S Lccn , SC converter stations are respectively denoted as S vsc1 , S vsc2 ,…,S vscm .

[0057] In this embodiment, the technical parameters of the simulation network include the parameters of each parallel hybrid DC system and the technical parameters of the AC network. Specifically, the converter parameters, DC line parameters, filter parameters, etc. of each LCC converter station in each parallel hybrid DC system are obtained. At the same time, the converter transformer parameters, MMC converter valve parameters, DC line parameters, etc. of each VSC converter station in each parallel hybrid DC system are obtained. In addition, the parameters of each component in the AC network, such as the generator parameters, line parameters, and load parameters, are obtained.

[0058] In this embodiment, the operating parameters of the simulation network include the arranged active power, reactive power, AC voltage and current, DC voltage and current, converter tap position, filter activation and deactivation status, and the command value, control mode, and selected balancing station of each converter station in each parallel hybrid DC system.

[0059] Step 102: Divide the simulation network according to simulation requirements to obtain an electromagnetic transient subsystem and an electromechanical transient subsystem, and select a hybrid simulation interface position.

[0060] In this embodiment, according to the simulation requirements, the simulation network containing the parallel hybrid DC system is divided into a network so that the simulation network divides the traditional AC power grid into an electromechanical transient subsystem and the parallel hybrid DC system into an electromagnetic transient subsystem, and the position of the hybrid simulation interface is set.

[0061] In this embodiment, a parallel hybrid DC system is divided into an electromagnetic transient subsystem, and detailed electromagnetic transient modeling and analysis is performed on the parallel hybrid DC system. Depending on the simulation analysis requirements, the electromagnetic transient subsystem can include only a single parallel hybrid DC system. Alternatively, based on the connection relationship between the DC systems, as an example in this embodiment, if multiple DC lines with the same receiving or sending end are divided into the same electromagnetic subsystem, the AC network connecting each DC line needs to be divided into the electromagnetic subsystem as well, facilitating the analysis of the mutual influence between the individual DC lines.

[0062] In this embodiment, the hybrid simulation interface location is selected based on actual simulation requirements. Since network division can occur on any AC tie line or tie transformer, any AC busbar can be selected as the interface busbar. Therefore, in this embodiment, the commutation busbar can be selected as the interface busbar. Alternatively, the interface busbar can be expanded within the AC system based on simulation requirements, allowing a portion of the AC network to be allocated to the electromagnetic transient subsystem, increasing flexibility in selecting the simulation interface location.

[0063] In this embodiment, the interface bus is used as the dividing line to divide the traditional AC power grid into the electromechanical transient network, and the parallel hybrid DC system is divided into the electromagnetic transient network. This network division method ensures that the hybrid simulation system only includes one electromechanical transient subsystem, one electromagnetic transient subsystem and one interface, forming a "one-to-one" interface mode. The simulation network division diagram is shown in Figure 4.

[0064] In this embodiment, the simulation network is divided. Different from the prior art in which the simulation system is divided into multiple sub-networks, in this embodiment, there is no need to consider the differences in transient response speed and computational complexity of multiple sub-networks, and there is no need to consider the coordination and cooperation between multiple sub-networks. The simulation interface is single, the interface data interaction volume is small, and the interface design is simple and reliable, which reduces the impact of the interface equivalent model on the calculation, helps to improve the simulation calculation accuracy, and can also meet the calculation speed requirements of electromagnetic-electromechanical hybrid simulation including parallel hybrid DC systems.

[0065] Step 103: Modeling the electromagnetic transient subsystem, the electromechanical transient subsystem, and the hybrid simulation interface position to generate an electromagnetic transient model, an electromechanical transient model, and an interface model; and splicing the electromagnetic transient model and the electromechanical transient model through the interface model to form a first electromechanical-electromagnetic hybrid simulation model.

[0066] In this embodiment, the electromagnetic transient subsystem, electromechanical transient subsystem, and hybrid simulation interface locations are modeled separately. Models of each component in the electromechanical transient network are constructed based on the electromechanical transient program, and an electromechanical transient model is established based on the corresponding electromechanical data files. Specifically, based on, but not limited to, the PSD-PSMODEL simulation program, a power flow data file *.dat and an electromechanical transient data file *.swi are established. The power flow data includes AC node data, AC line data, transformer data, and data on the DC lines, nodes, and converter transformers of the parallel hybrid DC system. The electromechanical transient data includes AC equipment data models such as generators, excitation, and speed regulation, as well as models of the LCC and VSC control systems in the parallel hybrid DC system.

[0067] In this embodiment, a model of each component in an electromagnetic transient network including a parallel hybrid DC system is constructed based on an electromagnetic transient program, and an electromagnetic transient model is generated and established based on the corresponding electromagnetic data file. Specifically, based on but not limited to the PSD-PSMODEL simulation program, a primary system and a control and protection system model including a parallel hybrid DC model are established. The primary system includes components such as a converter transformer, a 6-pulse / 12-pulse converter valve, an MMC converter valve, a smoothing reactor, a DC line, an AC filter, a DC filter, a grounding electrode, and a grounding electrode lead. As an example in this embodiment, the line can adopt a single / three-phase multi-PI model, a Bergeron model, or a frequency-dependent model; the converter transformer can adopt a dual-winding or triple-winding model; the converter valve can adopt a detailed model or a Thevenin equivalent model, or an integrated six-pulse converter model, an MMC average value model, or the like. Based on the parallel hybrid DC topology determined in step 101, the connection relationship between the components is established to form a primary system data file *.psm file. The control and protection system model adopts a hierarchical modular structure. The LCC converter station control system module includes control components such as the constant voltage control module, constant current control module, AMAX control module, and low-voltage current limiting module. The VSC converter station control system includes the outer-loop active power control module, the outer-loop reactive power control module, the inner-loop current control module, and the low-voltage ride-through module. Furthermore, it includes a coordinated control strategy module between the LCC and VSC converter stations, and a priority strategy table for each balancing station. In this embodiment, the control mode of each parallel hybrid DC system is determined based on the actual project design. Based on these control modules, the control and protection system files (*.udm files) for each parallel hybrid DC system are generated.

[0068] In this embodiment, interface data is constructed based on the selection of interface locations. The selection of interface locations must take into account the complexity of the interface algorithm and data processing to ensure the computational efficiency and numerical stability of the hybrid simulation. Typical interface data includes interface location information, network equivalence methods, iteration methods, data interaction, and the like. As an example in this embodiment, based on, but not limited to, the PSD-PSMODEL simulation program, an interface model for the electromechanical transient subsystem is established, and an interface model for the electromagnetic transient subsystem is also established. Specifically, the interface data includes interface information for the electromechanical portion and interface information in the electromagnetic transient file. The interface information in the electromagnetic transient file includes interface bus information, current, voltage, and power information at the interface bus, and the like. This interface information is reflected in the primary system file *.psm. The interface information in the electromechanical transient file includes interface location information, iteration methods, exchange power, and the like. This interface information is reflected in the electromechanical transient data file *.swi. Furthermore, the electromechanical transient interface information also needs to include the required electromagnetic transient model file.

[0069] In this embodiment, there is no need to set up multiple different simulation interface models, which simplifies the simulation interface model and reduces the impact of the interface equivalent model on the calculation, which helps to improve the accuracy of the simulation calculation. At the same time, it can also meet the calculation speed requirements of the electromechanical-electromagnetic hybrid simulation including the parallel hybrid DC system.

[0070] In this embodiment, after modeling the electromagnetic transient subsystem, electromechanical transient subsystem, and hybrid simulation interface locations, the electromechanical model and electromagnetic model are spliced ​​together using the interface data to establish an initial electromechanical-electromagnetic hybrid simulation model. Information such as the power exchanged at the interface is recorded. Specifically, based on, but not limited to, the PSD-PSMODEL simulation program, the established electromechanical interface model is entered in the form of a data card in a *.swi file, and the electromagnetic transient interface model is entered in a *.psm file. All power flow data *.dat, electromechanical transient data *.swi, electromagnetic transient primary files *.psm, and electromagnetic transient model control files *.udm are placed in the same folder. The electromagnetic and electromechanical data are spliced ​​together using the data card to form the first electromechanical-electromagnetic hybrid simulation model.

[0071] In this embodiment, the simulation program can call the corresponding electromagnetic transient model file by reading the electromechanical transient interface information data card, and enable the electromagnetic transient program by enabling the electromechanical transient program.

[0072] Step 104: Optimize the first electromechanical-electromagnetic hybrid simulation model according to the obtained basic parameters to generate a second electromechanical-electromagnetic hybrid simulation model; and perform simulation calculations on the power grid to be simulated using the second electromechanical-electromagnetic hybrid simulation model.

[0073] In this embodiment, DC initialization adjustment and model verification are performed on the first electromechanical-electromagnetic hybrid simulation model; the basic parameters of the simulation network containing the parallel hybrid DC system obtained in step 101 are combined with the first electromechanical-electromagnetic hybrid simulation model obtained in step 103 to perform power flow calculation, and obtain power flow data and power flow calculation results; the power flow data and the power flow calculation results are read as the basic operating points of the hybrid DC system, and the hybrid DC system is initialized and adjusted based on the power flow results, so as to obtain the first electromechanical-electromagnetic hybrid simulation data for stable operation.

[0074] Specifically, this embodiment completes the initialization and adjustment of a parallel hybrid DC system through a classified, step-by-step zero-start simulation method based on power flow results. Initialization of the hybrid DC system is first divided into two parts: initialization of the LCC converter station and initialization of the VSC converter station. In this embodiment, the converter tap information of the LCC converter station is first adjusted based on the power flow data. Since LCC converter stations generally use a constant current control mode, the DC voltage of the LCC converter station is first established. Constant current starting control is then performed to establish the DC current and complete the DC starting. Due to the differences between the electromagnetic simulation model and the power flow model, the converter tap information and other information are repeatedly adjusted to ensure that the DC voltage, trigger angle, and arc extinction angle of the LCC converter station in the electromagnetic transient model are consistent with the power flow data results.

[0075] In this embodiment, since there is only one balancing station in the hybrid DC system, and the VSC station is generally selected as the balancing station, first obtain the balancing station by obtaining the power flow data and the power flow calculation results, and record it as S vcsk The voltage operating point of the entire DC network is determined based on the voltage command value of the balancing station. Based on the power flow results, the command values ​​and control modes for active / reactive power, DC / AC voltage, and other VSC converter stations are obtained. The command values ​​for active / reactive power, DC / AC voltage, and control mode are set for each VSC converter station. The control mode and priority of each VSC converter station as a balancing station are also set. Simulation methods are used to directly start each VSC station, establish the voltage of the entire DC network, and complete the initialization of each VSC station.

[0076] In this embodiment, by verifying the consistency of the data of the electromechanical transient model and the data of the electromagnetic transient model, the first electromechanical-electromagnetic simulation data of stable operation is obtained, and based on the obtained first electromechanical-electromagnetic simulation data of stable operation, the data of the first electromechanical-electromagnetic hybrid simulation model is updated to obtain the second electromechanical-electromagnetic hybrid simulation model.

[0077] As an example in this embodiment, the hybrid simulation model may be optimized by verifying with other simulation models and measured waveforms.

[0078] In this embodiment, based on grid simulation requirements, a second electromechanical-electromagnetic hybrid simulation model is used to simulate and calculate typical grid faults and analyze grid characteristics. Specifically, faults such as AC short circuits and line breaks, as well as DC faults and DC restarts, are simulated and analyzed. The voltage, current, and trigger angle waveforms of the parallel hybrid DC system are analyzed, along with the transient characteristics of the parallel hybrid DC system and its interaction with the AC and DC grids.

[0079] See also Figure 2 , Figure 2FIG. 1 is a structural diagram of an embodiment of an electromechanical-electromagnetic hybrid simulation device based on a hybrid DC system provided by the present invention. Figure 2 As shown, the structure includes an acquisition module 201, a network division module 202, a model splicing module 203 and a model optimization module 204, which are specifically as follows:

[0080] The acquisition module 201 is used to acquire basic parameters of a simulation network including a parallel hybrid DC system.

[0081] In this embodiment, the topology of each parallel hybrid DC system in the simulation network is obtained, and the grid structure parameters, technical parameters and operating parameters of the simulation network are obtained at the same time. The topology of the parallel hybrid DC system is as follows: Figure 3 shown.

[0082] In this embodiment, the grid structure parameters of the simulation network include the number of parallel hybrid DC systems, the number of LCC converter stations and the number of VSC converter stations contained in each parallel hybrid DC system, and the LCC converter stations are respectively denoted as S Lcc1 , S Lcc2 ,…,S Lccn , SC converter stations are respectively denoted as S vsc1 , S vsc2 ,…,S vscm .

[0083] In this embodiment, the technical parameters of the simulation network include the parameters of each parallel hybrid DC system and the technical parameters of the AC network. Specifically, the converter parameters, DC line parameters, filter parameters, etc. of each LCC converter station in each parallel hybrid DC system are obtained. At the same time, the converter transformer parameters, MMC converter valve parameters, DC line parameters, etc. of each VSC converter station in each parallel hybrid DC system are obtained. In addition, the parameters of each component in the AC network, such as the generator parameters, line parameters, and load parameters, are obtained.

[0084] In this embodiment, the operating parameters of the simulation network include the arranged active power, reactive power, AC voltage and current, DC voltage and current, converter tap position, filter activation and deactivation status, and the command value, control mode, and selected balancing station of each converter station in each parallel hybrid DC system.

[0085] The network partitioning module 202 is used to partition the simulation network according to simulation requirements, obtain an electromagnetic transient subsystem and an electromechanical transient subsystem, and select a hybrid simulation interface position.

[0086] In this embodiment, according to the simulation requirements, the simulation network containing the parallel hybrid DC system is divided into a network so that the simulation network divides the traditional AC power grid into an electromechanical transient subsystem and the parallel hybrid DC system into an electromagnetic transient subsystem, and the position of the hybrid simulation interface is set.

[0087] In this embodiment, a parallel hybrid DC system is divided into an electromagnetic transient subsystem, and detailed electromagnetic transient modeling and analysis is performed on the parallel hybrid DC system. Depending on the simulation analysis requirements, the electromagnetic transient subsystem can include only a single parallel hybrid DC system, or it can be based on the connection relationship between the DC systems. As an example in this embodiment, if multiple DC lines with the same receiving or sending end are divided into the same electromagnetic subsystem, the AC network connecting each DC line needs to be divided into the electromagnetic subsystem as well to facilitate analysis of the mutual influence between the DC lines.

[0088] In this embodiment, the hybrid simulation interface location is selected based on actual simulation requirements. Since network division can be performed on any AC tie line or tie transformer, any AC bus can serve as the interface bus. Therefore, in this embodiment, the commutation bus can be selected as the interface bus. Alternatively, the interface bus can be expanded within the AC system based on simulation requirements, allowing a portion of the AC network to be allocated to the electromagnetic transient subsystem, increasing flexibility in selecting the simulation interface location.

[0089] In this embodiment, the interface bus is used as the dividing line to divide the traditional AC power grid into the electromechanical transient network, and the parallel hybrid DC system is divided into the electromagnetic transient network. This network division method ensures that the hybrid simulation system only includes one electromechanical transient subsystem, one electromagnetic transient subsystem and one interface, forming a "one-to-one" interface mode. The simulation network division diagram is shown in Figure 4.

[0090] In this embodiment, the simulation network is divided. Different from the prior art in which the simulation system is divided into multiple sub-networks, in this embodiment, there is no need to consider the differences in transient response speed and computational complexity of multiple sub-networks, and there is no need to consider the coordination and cooperation between multiple sub-networks. The simulation interface is single, the interface data interaction volume is small, and the interface design is simple and reliable, which reduces the impact of the interface equivalent model on the calculation, helps to improve the simulation calculation accuracy, and can also meet the calculation speed requirements of electromagnetic-electromechanical hybrid simulation including parallel hybrid DC systems.

[0091] The model splicing module 203 is used to model the electromagnetic transient subsystem, the electromechanical transient subsystem and the hybrid simulation interface position, generate an electromagnetic transient model, an electromechanical transient model and an interface model, and splice the electromagnetic transient model and the electromechanical transient model through the interface model to form a first electromechanical-electromagnetic hybrid simulation model.

[0092] In this embodiment, the electromagnetic transient subsystem, electromechanical transient subsystem, and hybrid simulation interface locations are modeled separately. Models of each component in the electromechanical transient network are constructed based on the electromechanical transient program, and an electromechanical transient model is established based on the corresponding electromechanical data files. Specifically, based on, but not limited to, the PSD-PSMODEL simulation program, a power flow data file *.dat and an electromechanical transient data file *.swi are established. The power flow data includes AC node data, AC line data, transformer data, and data on the DC lines, nodes, and converter transformers of the parallel hybrid DC system. The electromechanical transient data includes AC equipment data models such as generators, excitation, and speed regulation, as well as models of the LCC and VSC control systems in the parallel hybrid DC system.

[0093] In this embodiment, a model of each component in the electromagnetic transient network including a parallel hybrid DC system is constructed based on an electromagnetic transient program, and an electromagnetic transient model is generated and established based on the corresponding electromagnetic data file. Specifically, based on but not limited to the PSD-PSMODEL simulation program, a primary system and control and protection system model including the parallel hybrid DC model is established. The primary system includes components such as a converter transformer, a 6-pulse / 12-pulse converter valve, an MMC converter valve, a smoothing reactor, a DC line, an AC filter, a DC filter, a grounding electrode, and a grounding electrode lead. As an example in this embodiment, the line can adopt a single / three-phase multi-PI model, a Bergeron model, or a frequency-dependent model; the converter transformer can adopt a dual-winding or triple-winding model; the converter valve can adopt a detailed model or a Thevenin equivalent model, or an integrated six-pulse converter model, an MMC average value model, or the like. Based on the parallel hybrid DC topology determined in the acquisition module 201, the connection relationship between the components is established to form a primary system data file *.psm file. The control and protection system model adopts a hierarchical modular structure. The LCC converter station control system module includes control components such as the constant voltage control module, constant current control module, AMAX control module, and low-voltage current limiting module. The VSC converter station control system includes the outer-loop active power control module, the outer-loop reactive power control module, the inner-loop current control module, and the low-voltage ride-through module. Furthermore, it includes a coordinated control strategy module between the LCC and VSC converter stations, and a priority strategy table for each balancing station. In this embodiment, the control mode of each parallel hybrid DC system is determined based on the actual project design. Based on these control modules, the control and protection system files (*.udm files) for each parallel hybrid DC system are generated.

[0094] In this embodiment, interface data is constructed based on the selection of interface locations. The selection of interface locations must take into account the complexity of the interface algorithm and data processing to ensure the computational efficiency and numerical stability of the hybrid simulation. Typical interface data includes interface location information, network equivalence methods, iteration methods, data interaction, and the like. As an example in this embodiment, based on, but not limited to, the PSD-PSMODEL simulation program, an interface model for the electromechanical transient subsystem is established, and an interface model for the electromagnetic transient subsystem is also established. Specifically, the interface data includes interface information for the electromechanical portion and interface information in the electromagnetic transient file. The interface information in the electromagnetic transient file includes interface bus information, current, voltage, and power information at the interface bus, and the like. This interface information is reflected in the primary system file *.psm. The interface information in the electromechanical transient file includes interface location information, iteration methods, exchange power, and the like. This interface information is reflected in the electromechanical transient data file *.swi. Furthermore, the electromechanical transient interface information also needs to include the required electromagnetic transient model file.

[0095] In this embodiment, there is no need to set up multiple different simulation interface models, which simplifies the simulation interface model and reduces the impact of the interface equivalent model on the calculation, which helps to improve the accuracy of the simulation calculation. At the same time, it can also meet the calculation speed requirements of the electromechanical-electromagnetic hybrid simulation including the parallel hybrid DC system.

[0096] In this embodiment, after modeling the electromagnetic transient subsystem, electromechanical transient subsystem, and hybrid simulation interface locations, the electromechanical model and electromagnetic model are spliced ​​together using the interface data to establish an initial electromechanical-electromagnetic hybrid simulation model. Information such as the power exchanged at the interface is recorded. Specifically, based on, but not limited to, the PSD-PSMODEL simulation program, the established electromechanical interface model is entered in the form of a data card in a *.swi file, and the electromagnetic transient interface model is entered in a *.psm file. All power flow data *.dat, electromechanical transient data *.swi, electromagnetic transient primary files *.psm, and electromagnetic transient model control files *.udm are placed in the same folder. The electromagnetic and electromechanical data are spliced ​​together using the data card to form the first electromechanical-electromagnetic hybrid simulation model.

[0097] In this embodiment, the simulation program can call the corresponding electromagnetic transient model file by reading the electromechanical transient interface information data card, and enable the electromagnetic transient program by enabling the electromechanical transient program.

[0098] The model optimization module 204 is used to optimize the first electromechanical-electromagnetic hybrid simulation model according to the obtained basic parameters to generate a second electromechanical-electromagnetic hybrid simulation model; and perform simulation calculations on the power grid to be simulated through the second electromechanical-electromagnetic hybrid simulation model.

[0099] In this embodiment, DC initialization adjustment and model verification are performed on the first electromechanical-electromagnetic hybrid simulation model; the basic parameters of the simulation network containing the parallel hybrid DC system obtained in the acquisition module 201 are combined with the first electromechanical-electromagnetic hybrid simulation model obtained in the model splicing module 203 to perform power flow calculation, and obtain power flow data and power flow calculation results; the power flow data and power flow calculation results are read as the basic operating points of the hybrid DC system, and the hybrid DC system is initialized and adjusted based on the power flow results, so as to obtain the first electromechanical-electromagnetic hybrid simulation data for stable operation.

[0100] Specifically, this embodiment completes the initialization and adjustment of a parallel hybrid DC system through a classified, step-by-step zero-start simulation method based on power flow results. Initialization of the hybrid DC system is first divided into two parts: initialization of the LCC converter station and initialization of the VSC converter station. In this embodiment, the converter tap information of the LCC converter station is first adjusted based on the power flow data. Since LCC converter stations generally use a constant current control mode, the DC voltage of the LCC converter station is first established. Constant current starting control is then performed to establish the DC current and complete the DC starting. Due to the differences between the electromagnetic simulation model and the power flow model, the converter tap information and other information are repeatedly adjusted to ensure that the DC voltage, trigger angle, and arc extinction angle of the LCC converter station in the electromagnetic transient model are consistent with the power flow data results.

[0101] In this embodiment, since there is only one balancing station in the hybrid DC system, and the VSC station is generally selected as the balancing station, first obtain the balancing station by obtaining the power flow data and the power flow calculation results, and record it as S vcsk The voltage operating point of the entire DC network is determined based on the voltage command value of the balancing station. Based on the power flow results, the command values ​​and control modes for active / reactive power, DC / AC voltage, and other VSC converter stations are obtained. The command values ​​for active / reactive power, DC / AC voltage, and control mode are set for each VSC converter station. The control mode and priority of each VSC converter station as a balancing station are also set. Simulation methods are used to directly start each VSC station, establish the voltage of the entire DC network, and complete the initialization of each VSC station.

[0102] In this embodiment, by verifying the consistency of the data of the electromechanical transient model and the data of the electromagnetic transient model, the first electromechanical-electromagnetic simulation data of stable operation is obtained, and based on the obtained first electromechanical-electromagnetic simulation data of stable operation, the data of the first electromechanical-electromagnetic hybrid simulation model is updated to obtain the second electromechanical-electromagnetic hybrid simulation model.

[0103] As an example in this embodiment, the hybrid simulation model may be optimized by verifying with other simulation models and measured waveforms.

[0104] In this embodiment, based on grid simulation requirements, a second electromechanical-electromagnetic hybrid simulation model is used to simulate and calculate typical grid faults and analyze grid characteristics. Specifically, faults such as AC short circuits and line breaks, as well as DC faults and DC restarts, are simulated and analyzed. The voltage, current, and trigger angle waveforms of the parallel hybrid DC system are analyzed, along with the transient characteristics of the parallel hybrid DC system and its interaction with the AC and DC grids.

[0105] In summary, the present invention provides an electromechanical-electromagnetic hybrid simulation method and device based on a hybrid DC system. The method obtains the basic parameters of a simulation network containing a parallel hybrid DC system; divides the simulation network according to simulation requirements to obtain an electromagnetic transient subsystem and an electromechanical transient subsystem, and simultaneously selects a hybrid simulation interface location; models the electromagnetic transient subsystem, the electromechanical transient subsystem, and the hybrid simulation interface location to generate an electromagnetic transient model, an electromechanical transient model, and an interface model; and splices the electromagnetic transient model and the electromechanical transient model through the interface model to form a first electromechanical-electromagnetic hybrid simulation model; optimizes the first electromechanical-electromagnetic hybrid simulation model based on the obtained basic parameters to generate a second electromechanical-electromagnetic hybrid simulation model; and simulates the power grid to be simulated through the second electromechanical-electromagnetic hybrid simulation model. Compared with the prior art, the present invention partially adopts electromagnetic transient simulation on the basis of electromechanical transient simulation to achieve electromechanical-electromagnetic transient hybrid simulation calculation, improves simulation accuracy, and facilitates accurate and rapid simulation analysis of large power grids.

[0106] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A hybrid electromechanical-electromagnetic simulation method based on a hybrid DC system, characterized in that: include: Obtain basic parameters of the simulation network containing the parallel hybrid DC system; According to simulation requirements, the simulation network is divided to obtain an electromagnetic transient subsystem and an electromechanical transient subsystem, and a hybrid simulation interface position is selected; Modeling the electromagnetic transient subsystem, the electromechanical transient subsystem, and the hybrid simulation interface position to generate an electromagnetic transient model, an electromechanical transient model, and an interface model, and splicing the electromagnetic transient model and the electromechanical transient model through the interface model to form a first electromechanical-electromagnetic hybrid simulation model; performing DC initialization adjustment and model verification on the first electromechanical-electromagnetic hybrid simulation model based on the obtained basic parameters; adjusting the converter tap information of the LCC converter station by reading and adjusting the converter tap information of the LCC converter station based on the power flow data so that the variables of the LCC converter station in the electromagnetic transient model are consistent with the power flow data; The operating parameters of the VSC converter station are read and set according to the power flow calculation results, and the consistency of the data of the electromechanical transient model and the data of the electromagnetic transient model is verified to obtain the electromechanical-electromagnetic hybrid simulation data of stable operation, and the data of the first electromechanical-electromagnetic hybrid simulation model is updated according to the electromechanical-electromagnetic hybrid simulation data of stable operation to generate a second electromechanical-electromagnetic hybrid simulation model; and the power grid to be simulated is simulated by using the second electromechanical-electromagnetic hybrid simulation model.

2. The electromechanical-electromagnetic hybrid simulation method based on a hybrid DC system according to claim 1, characterized in that: Obtain the basic parameters of the simulation network containing the parallel hybrid DC system, specifically: Obtaining the topological structure of each parallel hybrid DC system in the simulation network, and simultaneously obtaining the grid structure parameters, technical parameters, and operating parameters of the simulation network; The grid structure parameters include the number of parallel hybrid DC systems, the number of LCC converter stations and the number of VSC converter stations contained in each parallel hybrid DC system; The technical parameters include parameters of each parallel hybrid DC system and technical parameters of the AC network; The operating parameters include the arranged active power, reactive power, AC voltage and current, DC voltage and current, converter tap position, filter activation and deactivation status, and the command value, control mode, and selected balancing station of each converter station in each parallel hybrid DC system.

3. The electromechanical-electromagnetic hybrid simulation method based on a hybrid DC system according to claim 2, characterized in that: According to the simulation requirements, the simulation network is divided into the electromagnetic transient subsystem and the electromechanical transient subsystem, and the hybrid simulation interface position is selected, specifically: According to the simulation requirements, the simulation network containing the parallel hybrid DC system is divided into a network so that the simulation network divides the traditional AC power grid into an electromechanical transient subsystem and the parallel hybrid DC system into an electromagnetic transient subsystem, and the position of the hybrid simulation interface is set.

4. The electromechanical-electromagnetic hybrid simulation method based on a hybrid DC system according to claim 3, characterized in that: Modeling the electromagnetic transient subsystem, the electromechanical transient subsystem, and the hybrid simulation interface position to generate an electromagnetic transient model, an electromechanical transient model, and an interface model, specifically: Build the model of each component in the electromechanical transient network based on the electromechanical transient program, and form and establish the electromechanical transient model based on the corresponding electromechanical data file; Based on the electromagnetic transient program, a model of each component in the electromagnetic transient network including the parallel hybrid DC system is constructed, and an electromagnetic transient model is established based on the corresponding electromagnetic data file; According to the interface position, the interface data is constructed, and based on the PSD-PSMODEL simulation program, the interface model of the electromechanical transient subsystem is established, and the interface model of the electromagnetic transient subsystem is established at the same time.

5. An electromechanical-electromagnetic hybrid simulation device based on a hybrid DC system, characterized in that: include: Acquisition module, network partition module, model splicing module and model optimization module; The acquisition module is used to obtain basic parameters of a simulation network containing a parallel hybrid DC system; The network partitioning module is used to partition the simulation network according to simulation requirements to obtain an electromagnetic transient subsystem and an electromechanical transient subsystem, and simultaneously select a hybrid simulation interface position; The model splicing module is used to model the electromagnetic transient subsystem, the electromechanical transient subsystem and the hybrid simulation interface position to generate an electromagnetic transient model, an electromechanical transient model and an interface model, and splice the electromagnetic transient model and the electromechanical transient model through the interface model to form a first electromechanical-electromagnetic hybrid simulation model; The model optimization module is configured to perform DC initialization adjustment and model verification on the first electromechanical-electromagnetic hybrid simulation model based on the acquired basic parameters; and to adjust the converter tap information of the LCC converter station by reading and adjusting the converter tap information based on the power flow data so that the variables of the LCC converter station in the electromagnetic transient model are consistent with the power flow data. The operating parameters of the VSC converter station are read and set according to the power flow calculation results, and the consistency of the data of the electromechanical transient model and the data of the electromagnetic transient model is verified to obtain the electromechanical-electromagnetic hybrid simulation data of stable operation, and the data of the first electromechanical-electromagnetic hybrid simulation model is updated according to the electromechanical-electromagnetic hybrid simulation data of stable operation to generate a second electromechanical-electromagnetic hybrid simulation model; and the power grid to be simulated is simulated by using the second electromechanical-electromagnetic hybrid simulation model.

6. The electromechanical-electromagnetic hybrid simulation device based on a hybrid DC system according to claim 5, characterized in that: The acquisition module is used to obtain basic parameters of the simulation network containing the parallel hybrid DC system, specifically: Obtaining the topological structure of each parallel hybrid DC system in the simulation network, and simultaneously obtaining the grid structure parameters, technical parameters, and operating parameters of the simulation network; The grid structure parameters include the number of parallel hybrid DC systems, the number of LCC converter stations and the number of VSC converter stations contained in each parallel hybrid DC system; The technical parameters include parameters of each parallel hybrid DC system and technical parameters of the AC network; The operating parameters include the arranged active power, reactive power, AC voltage and current, DC voltage and current, converter tap position, filter activation and deactivation status, and the command value, control mode, and selected balancing station of each converter station in each parallel hybrid DC system.

7. The electromechanical-electromagnetic hybrid simulation device based on a hybrid DC system according to claim 6, characterized in that: The network partitioning module is used to partition the simulation network according to simulation requirements to obtain the electromagnetic transient subsystem and the electromechanical transient subsystem, and select the hybrid simulation interface position, specifically: According to the simulation requirements, the simulation network containing the parallel hybrid DC system is divided into a network so that the simulation network divides the traditional AC power grid into an electromechanical transient subsystem and the parallel hybrid DC system into an electromagnetic transient subsystem, and the position of the hybrid simulation interface is set.

8. The electromechanical-electromagnetic hybrid simulation device based on a hybrid DC system according to claim 7, characterized in that: The model splicing module is used to model the electromagnetic transient subsystem, the electromechanical transient subsystem and the hybrid simulation interface position to generate an electromagnetic transient model, an electromechanical transient model and an interface model, specifically: Build the model of each component in the electromechanical transient network based on the electromechanical transient program, and form and establish the electromechanical transient model based on the corresponding electromechanical data file; Based on the electromagnetic transient program, a model of each component in the electromagnetic transient network including the parallel hybrid DC system is constructed, and an electromagnetic transient model is established based on the corresponding electromagnetic data file; According to the interface position, the interface data is constructed, and based on the PSD-PSMODEL simulation program, the interface model of the electromechanical transient subsystem is established, and the interface model of the electromagnetic transient subsystem is established at the same time.

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