Flexible direct current electromagnetic transient modeling method and system

Abstract

The invention discloses a flexible direct-current electromagnetic transient modeling method. The method comprises the following steps: acquiring data information of a target flexible direct-current power system; carrying out modular modeling on the target flexible DC power system based on simulation software; modeling a structured controller of the target flexible DC power system based on simulation software; establishing an electromagnetic transient simulation model of the target flexible DC power system; performing simulation test and correction on the electromagnetic transient simulation model of the target flexible DC power system; and final flexible direct current electromagnetic transient modeling is completed according to a correction result. The invention also discloses a system for realizing the flexible direct current electromagnetic transient modeling method. According to the method, modular modeling and correction are carried out on each part of the target flexible direct-current power system, flexible direct-current electromagnetic transient modeling is realized, the simulation requirements of the power system in different stages such as planning, design and dispatching operation can be met, the reliability is higher, and the flexibility is better.

Description

Technical Field

[0001] The invention belongs to the field of electrical automation, and in particular relates to a flexible direct current electromagnetic transient modeling method and system. Background Art

[0002] With the development of economy and technology and the improvement of people's living standards, electricity has become an indispensable secondary energy source in people's production and life, bringing endless convenience to people's production and life. Therefore, ensuring the stable and reliable supply of electricity has become one of the most important tasks of the power system.

[0003] Power system simulation is an important way to fully understand the transient and dynamic characteristics of power systems. Its basic principle is to obtain the dynamic behavior and operating characteristics of power systems through calculations based on the established mathematical model of power system components. Power system dynamic simulation technology can be divided into short-term electromagnetic transient simulation, long-term electromechanical transient simulation, and medium- and long-term dynamic simulation based on the time scale. Among them, electromagnetic transient simulation is mainly used to simulate the mutual conversion of electricity and magnetism in power systems and the transition process of circuits in detail. It can study the transient problems of power system operation, resonance transient, fault transient, and control system. Electromechanical transient simulation starts from the perspective of the power system as a whole and studies three types of stability problems: synchronous operation stability, frequency stability, and voltage stability of the power system.

[0004] Flexible DC technology has been widely used in power systems due to its flexibility in topology and control strategy. Therefore, power system simulation for flexible DC technology is particularly important. Flexible DC technology has different simulation modeling requirements for electromagnetic transient models in different stages such as grid planning, design, and dispatching and operation. In the planning and design stage, the model needs to be adjusted flexibly and quickly according to the future grid characteristics and DC construction conditions; in the dispatching and operation stage after commissioning, the simulation accuracy of the model needs to be improved to ensure that the model can accurately depict the transient characteristics of the actual flexible DC. However, the current power system simulation solution is not suitable for the simulation requirements of today's flexible DC technology in terms of simulation flexibility. Summary of the invention

[0005] One of the purposes of the present invention is to provide a flexible DC electromagnetic transient modeling method with high reliability and good flexibility.

[0006] A second objective of the present invention is to provide a system for implementing the flexible DC electromagnetic transient modeling method.

[0007] The flexible DC electromagnetic transient modeling method provided by the present invention comprises the following steps:

[0008] S1. Acquire data information of the target flexible DC power system;

[0009] S2. According to the data information obtained in step S1, modular modeling of the target flexible DC power system is performed based on simulation software;

[0010] S3. Model the structured controller of the target flexible DC power system based on simulation software;

[0011] S4. Based on the model obtained in step S2 and step S3, an electromagnetic transient simulation model of the target flexible DC power system is established;

[0012] S5. Perform simulation test on the electromagnetic transient simulation model of the target flexible DC power system obtained in step S4, and make corrections;

[0013] S6. According to the correction result obtained in step S5, the final flexible DC electromagnetic transient modeling is completed.

[0014] According to the data information obtained in step S1, modular modeling of the target flexible DC power system is performed based on simulation software in step S2, which specifically includes the following steps:

[0015] Based on the PSModel simulation software, the topology structure is modified according to the modeling requirements of the electromagnetic transient model; the modification includes modifying the .psm file of electrical component information, modifying the .psm file of node information, and modifying the .sub file of the converter station topology structure;

[0016] Based on the PSModel simulation software, the parameters of each device are modified according to the modeling requirements of the electromagnetic transient model; the modification includes: modifying the .con file to modify the system parameters, and the system parameters include the capacity reference value, DC voltage reference value, grid-side and valve-side line voltage reference value, transformer capacity, reactance value, copper loss, number of converter valve submodules, converter valve submodule capacitance and converter valve bridge arm inductance.

[0017] The step S3 of modeling the structured controller of the target flexible DC power system based on the simulation software specifically includes the following steps:

[0018] Modeling structured controllers;

[0019] Determine the control strategy of each converter station; the control strategy includes a passive control mode, a DC voltage mode and a fixed active power mode;

[0020] Adjust the control system parameters:

[0021] Determine whether the converter station is in constant DC voltage mode:

[0022] If the converter station is in the constant DC voltage mode, the DC side line is disconnected and the active output current i dand reactive output current i q Whether it is possible to track the active current reference value i dref and reactive current reference value i qref According to the change of i dref and i qref Whether it is possible to track changes in DC voltage and reactive power or AC voltage and adjust the outer loop control parameters;

[0023] If the converter station is not in the constant DC voltage mode, the DC circuit is disconnected and the constant voltage source is connected; according to the active output current i d and reactive output current i q Can it track the active current reference value i dref and reactive current reference value i qref The control parameters of the phase-locked loop and the current inner loop are adjusted according to the change of the active current reference value i dref and reactive current reference value i qref Whether it is possible to track changes in active power and reactive power or AC side voltage and adjust the outer loop control parameters.

[0024] The modeling of the structured controller specifically includes the following steps:

[0025] A dual-loop control structure based on Park transformation is adopted to model the structured controller into a measurement unit, an outer-loop control unit, an inner-loop control unit and a valve control unit.

[0026] The measuring unit includes a filtering module, a three-phase-dq conversion module, a power calculation module, a phase-locked loop module, a power synchronization loop module and a fixed angular frequency module; the output end of the filtering module is connected to the power calculation module through the three-phase-dq conversion module; at the same time, the output end of the filtering module also outputs the output signal of the measuring unit through the phase-locked loop module, the power synchronization loop module and the fixed angular frequency module; the output of the power calculation module and the output of the filtering module are also the output of the measuring unit; the output of the measuring unit is used as a key signal;

[0027] The outer loop control unit includes a d-axis voltage control module, an active power control module, a DC voltage control module, a q-axis voltage control module, a five-power power control module, an AC voltage control module and a fault ride-through module; the input of the outer loop control unit is the output of the measurement unit; the outputs of the d-axis voltage control module, the active power control module and the DC voltage control module are all used as inputs of the fault ride-through module; the outputs of the q-axis voltage control module, the five-power power control module and the AC voltage control module are all used as inputs of the fault ride-through module; the output of the fault ride-through module is the output of the outer loop control unit; the output of the outer loop control unit is used as a current instruction;

[0028] The inner loop control unit includes a current inner loop control module, a DC control loop module and a three-phase-dq conversion module; the input of the inner loop control unit is the output of the outer loop control unit; the output of the current inner loop control module is converted by the three-phase-dq conversion module and used as the output of the inner loop control unit; the output of the inner loop control unit is used as a voltage command;

[0029] The valve control unit includes a circulating current suppression module and a sorting and pressure balancing module; the output of the circulating current suppression unit, the output of the inner loop control unit and the output of the DC control loop module are multiplied and processed by the sorting and pressure balancing module to obtain the output of the valve control unit; the output of the valve control unit is used as a trigger instruction.

[0030] The step S4, based on the model obtained in step S2 and step S3, establishes an electromagnetic transient simulation model of the target flexible DC power system, which specifically includes the following steps:

[0031] Initialize the target flexible DC power system: first start the fixed DC voltage control, then start the sending and receiving end converter stations to determine whether the constraints are met:

[0032]

[0033] Where P 送 is the active power output by all sending-end converter stations; P 受 Active power transmitted to all receiving converter stations; is the rated capacity of the fixed DC voltage station;

[0034] If the constraints are met, the simulation is performed directly;

[0035] If the constraints are not met, the unlocking sequence of the sending and receiving converter stations is modified and the constraints are checked again.

[0036] The step S5 of performing simulation test on the electromagnetic transient simulation model of the target flexible DC power system obtained in step S4 and correcting the model specifically includes the following steps:

[0037] Conduct steady-state performance test on the established electromagnetic transient simulation model of the target flexible DC power system: connect an ideal voltage source to the AC system, conduct step response test, change the active power, reactive power and DC voltage reference values, and judge whether the output active power, reactive power and established DC voltage of each converter station can meet the corresponding reference values ​​set: if not, modify the model;

[0038] Conduct fault performance test on the established electromagnetic transient simulation model of the target flexible DC power system: simulate short circuit faults at the AC side access points of different converter stations to observe whether the system model can recover and operate normally after the fault; if not, modify the model.

[0039] The present invention also provides a system for implementing the flexible DC electromagnetic transient modeling method, comprising a data acquisition module, a modular modeling module, a controller modeling module, a simulation modeling module, a model correction module and a modeling completion module; the data acquisition module, the modular modeling module, the controller modeling module, the simulation modeling module, the model correction module and the modeling completion module are connected in series in sequence; the data acquisition module is used to acquire data information of the target flexible DC power system and upload the data information to the modular modeling module; the modular modeling module is used to perform modular modeling of the target flexible DC power system based on the received data information and the acquired data information, based on the simulation software, and upload the data information to the controller modeling module; the control The device modeling module is used to model the structured controller of the target flexible DC power system based on the simulation software according to the received data information, and upload the data information to the simulation modeling module; the simulation modeling module is used to establish the electromagnetic transient simulation model of the target flexible DC power system based on the obtained model according to the received data information, and upload the data information to the model correction module; the model correction module is used to simulate and test the electromagnetic transient simulation model of the target flexible DC power system obtained according to the received data information, and correct it, and upload the data information to the modeling completion module; the modeling completion module is used to complete the final flexible DC electromagnetic transient modeling according to the received data information and the obtained correction results.

[0040] The flexible DC electromagnetic transient modeling method and system provided by the present invention not only realizes flexible DC electromagnetic transient modeling by modularly modeling and correcting various parts of the target flexible DC power system, but also can meet the simulation requirements of the power system at different stages such as planning, design, scheduling and operation, with higher reliability and better flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The figure is a schematic diagram of the method flow of the present invention.

[0042] Figure 2 It is a schematic diagram of the topological structure of the flexible DC structured control system model in the method of the present invention.

[0043] Figure 3 This is a schematic diagram of a typical scenario of large-scale renewable energy through flexible direct current networking in an embodiment of the method of the present invention.

[0044] Figure 4 Schematic diagram of the DC voltage waveform of the flexible DC system according to the method embodiment of the present invention.

[0045] Figure 5 Schematic diagram of AC voltage waveform of flexible DC system according to the method embodiment of the present invention.

[0046] Figure 6Schematic diagram of active power waveform of flexible direct current system according to the method embodiment of the present invention.

[0047] Figure 7 Schematic diagram of reactive power waveform of flexible DC system according to the method embodiment of the present invention.

[0048] Figure 8 This is a schematic diagram of the positive high-end power waveform of the converter station S2 during the fault test of the converter station S2 of the flexible direct current system according to the method embodiment of the present invention.

[0049] Fig. 9 Schematic diagram of power waveform of converter station S1 during fault test of flexible direct current system S2 according to the method embodiment of the present invention.

[0050] Fig.10 Schematic diagram of the functional modules of the system of the present invention. DETAILED DESCRIPTION

[0051] like Figure 1 The method flow chart of the method of the present invention is shown as follows: the flexible DC electromagnetic transient modeling method disclosed in the present invention comprises the following steps:

[0052] S1. Acquire data information of the target flexible DC power system;

[0053] S2. According to the data information obtained in step S1, modular modeling of the target flexible DC power system is performed based on simulation software; specifically, the steps include:

[0054] Based on the PSModel simulation software, the topology structure is modified according to the modeling requirements of the electromagnetic transient model; the modification includes modifying the .psm file of electrical component information, modifying the .psm file of node information, and modifying the .sub file of the converter station topology structure;

[0055] Based on the PSModel simulation software, the parameters of each device are modified according to the modeling requirements of the electromagnetic transient model; the modification includes: modifying the .con file to modify the system parameters, and the system parameters include the capacity reference value, the DC voltage reference value, the grid-side and valve-side line voltage reference value, the transformer capacity, the reactance value, the copper loss, the number of converter valve submodules, the converter valve submodule capacitance and the converter valve bridge arm inductance;

[0056] S3. Modeling the structured controller of the target flexible DC power system based on simulation software; specifically including the following steps:

[0057] Modeling a structured controller such as Figure 2 As shown; specifically includes the following steps:

[0058] A dual-loop control structure based on Park transformation is adopted to model the structured controller into a measurement unit, an outer-loop control unit, an inner-loop control unit and a valve control unit.

[0059] The measuring unit includes a filtering module, a three-phase-dq conversion module, a power calculation module, a phase-locked loop module, a power synchronization loop module and a fixed angular frequency module; the output end of the filtering module is connected to the power calculation module through the three-phase-dq conversion module; at the same time, the output end of the filtering module also outputs the output signal of the measuring unit through the phase-locked loop module, the power synchronization loop module and the fixed angular frequency module; the output of the power calculation module and the output of the filtering module are also the output of the measuring unit; the output of the measuring unit is used as a key signal;

[0060] The outer loop control unit includes a d-axis voltage control module, an active power control module, a DC voltage control module, a q-axis voltage control module, a five-power power control module, an AC voltage control module and a fault ride-through module; the input of the outer loop control unit is the output of the measurement unit; the outputs of the d-axis voltage control module, the active power control module and the DC voltage control module are all used as inputs of the fault ride-through module; the outputs of the q-axis voltage control module, the five-power power control module and the AC voltage control module are all used as inputs of the fault ride-through module; the output of the fault ride-through module is the output of the outer loop control unit; the output of the outer loop control unit is used as a current instruction;

[0061] The inner loop control unit includes a current inner loop control module, a DC control loop module and a three-phase-dq conversion module; the input of the inner loop control unit is the output of the outer loop control unit; the output of the current inner loop control module is converted by the three-phase-dq conversion module and used as the output of the inner loop control unit; the output of the inner loop control unit is used as a voltage command;

[0062] The valve control unit includes a circulation suppression module and a sorting and pressure balancing module; the output of the circulation suppression unit, the output of the inner loop control unit and the output of the DC control loop module are multiplied, and then processed by the sorting and pressure balancing module to obtain the output of the valve control unit; the output of the valve control unit is used as a trigger instruction;

[0063] Determine the control strategy of each converter station; the control strategy includes a passive control mode, a DC voltage mode and a fixed active power mode;

[0064] Adjust the control system parameters:

[0065] Determine whether the converter station is in constant DC voltage mode:

[0066] If the converter station is in the constant DC voltage mode, the DC side line is disconnected and the active output current i d and reactive output current i q Whether it is possible to track the active current reference value i drefand reactive current reference value i qref According to the change of i dref and i qref Whether it is possible to track changes in DC voltage and reactive power or AC voltage and adjust the outer loop control parameters;

[0067] If the converter station is not in the constant DC voltage mode, the DC circuit is disconnected and the constant voltage source is connected; according to the active output current i d and reactive output current i q Can it track the active current reference value i dref and reactive current reference value i qref The control parameters of the phase-locked loop and the current inner loop are adjusted according to the change of the active current reference value i dref and reactive current reference value i qref Whether it is possible to track the changes in active power and reactive power or AC side voltage and adjust the outer loop control parameters;

[0068] S4. Based on the models obtained in step S2 and step S3, an electromagnetic transient simulation model of the target flexible DC power system is established; specifically comprising the following steps:

[0069] Initialize the target flexible DC power system: first start the fixed DC voltage control, then start the sending and receiving end converter stations to determine whether the constraints are met:

[0070]

[0071] Where P 送 is the active power output by all sending-end converter stations; P 受 Active power transmitted to all receiving converter stations; is the rated capacity of the fixed DC voltage station;

[0072] If the constraints are met, the simulation is performed directly;

[0073] If the constraints are not met, the unlocking order of the sending and receiving converter stations is modified and the constraint conditions are checked again;

[0074] S5. Perform simulation test on the electromagnetic transient simulation model of the target flexible DC power system obtained in step S4 and correct it; specifically comprising the following steps:

[0075] Conduct steady-state performance test on the established electromagnetic transient simulation model of the target flexible DC power system: connect an ideal voltage source to the AC system, conduct step response test, change the active power, reactive power and DC voltage reference values, and judge whether the output active power, reactive power and established DC voltage of each converter station can meet the corresponding reference values ​​set: if not, modify the model;

[0076] Conduct fault performance tests on the established electromagnetic transient simulation model of the target flexible DC power system: simulate short-circuit faults at the AC access points of different converter stations to observe whether the system model can recover and operate normally after the fault. If not, modify the model;

[0077] S6. According to the correction result obtained in step S5, the final flexible DC electromagnetic transient modeling is completed.

[0078] The method of the present invention is further described below in conjunction with an embodiment:

[0079] like Figure 3 The following is a typical scenario of large-scale renewable energy connected to the grid through flexible direct current (DC), including four modes of flexible direct current access to the grid:

[0080] When the converter station is connected to the clean energy island power grid - after the large-scale new energy base is collected through the AC line, the power is directly sent out through the converter station, and there is no AC electrical connection with the main grid at the sending end. The converter station adopts a passive or grid-forming control mode;

[0081] The converter station is connected to the AC main grid at the sending end: large-scale new energy bases are connected to the AC main grid at the sending end, and then the power is sent out through the converter station. The clean energy base has an AC electrical connection with the main grid, and the converter station adopts a grid-following or grid-building control mode;

[0082] The converter station is connected to the receiving AC main grid - the flexible DC converter station is connected to the load center of the receiving grid, which contains multiple types of equipment such as new energy, synchronous machines, static loads and dynamic loads. The converter station adopts a grid-following control mode of fixed DC voltage or fixed active power;

[0083] The converter station is connected to the load isolated network - the flexible DC converter station is connected to the load isolated network, and the isolated network only includes static load and dynamic load. The converter station adopts passive or grid-building control mode to supply power to the load isolated network.

[0084] The topological structure and equipment parameters of each flexible direct current converter station are preliminarily determined. Considering the large capacity of each flexible direct current converter station in this scenario, a true bipolar wiring form is adopted. The equipment parameters of each converter station are shown in Table 1 below:

[0085] Table 1 Schematic diagram of flexible DC converter station parameters

[0086] parameter S1 S2 S3 S4 Rated frequency on AC side 50HZ 50HZ 50HZ 50HZ DC voltage reference value 400kV 400kV 400kV 800kV Capacity benchmark 500MVA 1000MVA 1000MVA 1000MVA Converter capacity 600MVA 1200MVA 1200MVA 1200MVA Commutation Reactance 18％ 18％ 18％ 18％ Commutation ratio 525kV / 232.7kV 525kV / 232.7kV 525kV / 232.7kV 230kV / 460kV Number of submodules 244 244 244 244 Bridge arm inductance 0.075H 0.075H 0.075H 0.075H Submodule capacitance 15000μF 15000μF 15000μF 15000μF

[0087] According to the planning scheme, based on the PSModel simulation platform, flexible direct current electromagnetic transient modeling is carried out to modify the electrical system and control system parameters:

[0088] Build a detailed electromagnetic transient model of a hybrid cascaded multi-terminal DC electrical system. Take the flexible direct access typical scenario 1 as an example, where the converter station S1 is connected to the clean energy island grid. Modify the electrical parameters in the .con file, including the DC voltage reference value, transmission capacity reference value, and converter transformer and converter valve parameters.

[0089] Modify the control system parameters according to the access situation. Converter station S1 is connected to the clean energy island grid, where passive control is adopted. Modify the control parameters in the .con file, including d and q axis control methods, AC and DC voltage reference values, and active power reference values. In addition, in this example, converter stations S1 and S4 adopt passive control, converter station S2 adopts grid-forming control, and converter station S3 adopts fixed DC voltage grid-following control;

[0090] Initialize the flexible direct current electromagnetic transient model and check the voltage and power of key equipment in the system:

[0091] Determine the unlocking sequence of the flexible DC converter station: start the fixed DC voltage station first, and then start other sending and receiving converter stations. Unlock the S3 converter station in 0.1s, unlock the S2 converter station in 0.5s, and unlock the S1 and S4 converter stations at the same time in 1.0s. According to the control mode of each converter station, determine the initialization strategy of the converter station and the access to the power grid as follows:

[0092] For the S1 converter station and the connected AC power grid, it is set to start the clamping voltage source of the new energy side and the S1 converter station at 0.0s, unlock the new energy equipment at 0.1s, unlock the S1 converter station at 1.0s, cut off the clamping voltage source on the new energy side at 2.3s, and cut off the clamping voltage source of the S1 converter station at 3.0s, and merge into the S1 converter station at the same time.

[0093] For the S2 converter station and the connected AC power grid, it is set to start the clamped voltage source, synchronous machine and motor on the new energy side at 0.0s, unlock the new energy equipment at 0.1s, unlock the flexible DC converter station at 0.5s, cut off the clamped voltage source on the new energy side at 2.3s, unlock the speed of the AC synchronous machine and motor at 2.5s, and start the excitation and speed regulation system of the AC synchronous machine at 2.8.

[0094] For the S3 converter station and the connected AC power grid, the clamping voltage sources of the AC synchronous machine, motor, renewable energy side and flexible DC side are started at 0.0s, the renewable energy equipment and flexible DC converter station are unlocked at 0.1s, the clamping voltage source on the flexible DC side is cut off at 1.6s, the clamping voltage source on the renewable energy side is cut off at 2.3s, the speed of the AC synchronous machine and motor is unlocked at 2.5s, and the excitation and speed regulation system of the AC synchronous machine is started at 2.8s.

[0095] For the S4 converter station and the connected AC power grid, set the start clamping voltage source at 0.0s, unlock the converter station at 1.0s, cut off the S4 clamping voltage source at 2.5s and merge into the converter station, and unlock the motor speed at 3.0s.

[0096] Check the voltage and power of key system equipment. Figure 4 is the initialization waveform of the multi-terminal flexible DC. Figure 4 is the bipolar DC voltage, the red and blue curves represent the DC voltage of pole 1 and pole 2 respectively; Figure 5 is the AC voltage at the converter station connection point, Figure 6 is the active power of the converter station, Figure 7 is the reactive power of the converter station. The red, blue, green and pink curves represent the S1, S2, S3 and S4 converter stations respectively. Within 4.0s, the DC voltage, AC voltage and AC power of each converter station reached a stable state. During the initialization process, S3 was able to maintain a constant DC voltage, and the flexible DC system was able to maintain stable operation.

[0097] Conduct steady-state performance tests on converter stations S1, S2, S3 and S4 respectively to verify whether the output power and established DC voltage of each converter station meet the requirements;

[0098] Conduct three-phase instantaneous short-circuit fault tests at the AC interface of the converter stations S1, S2, S3 and S4 respectively to observe whether the flexible DC model can operate normally after the fault. If not, continue to adjust the control system to achieve normal operation of the flexible DC model after the fault. Here, the three-phase instantaneous short-circuit fault test is conducted on the AC side of the S2 converter station. The short-circuit fault is connected 3s after the flexible DC system is started. Figure 8 Output active power and reactive power curves of the positive high-end converter valve of S2 converter station. Fig. 9 The active power and reactive power output by the S1 converter station. It can be seen that after the short-circuit fault occurs, the power curve can recover to a stable operation after fluctuations. Similarly, it can be checked whether the output power of other converters can operate normally;

[0099] After completing the above tests, a full electromagnetic transient simulation verification is carried out. The outputs of the flexible DC model normally meet the grid operation requirements, and the flexible DC electromagnetic transient modeling based on the PSModel simulation software is completed.

[0100] like Fig.10The functional module schematic diagram of the system of the present invention is shown as follows: the system disclosed in the present invention for implementing the flexible DC electromagnetic transient modeling method comprises a data acquisition module, a modular modeling module, a controller modeling module, a simulation modeling module, a model correction module and a modeling completion module; the data acquisition module, the modular modeling module, the controller modeling module, the simulation modeling module, the model correction module and the modeling completion module are connected in series in sequence; the data acquisition module is used to acquire data information of the target flexible DC power system and upload the data information to the modular modeling module; the modular modeling module is used to perform modular modeling of the target flexible DC power system based on the received data information and the acquired data information, based on the simulation software, and upload the data information to the controller The controller modeling module is used to model the structured controller of the target flexible DC power system based on the simulation software according to the received data information, and upload the data information to the simulation modeling module; the simulation modeling module is used to establish the electromagnetic transient simulation model of the target flexible DC power system based on the obtained model according to the received data information, and upload the data information to the model correction module; the model correction module is used to simulate and test the electromagnetic transient simulation model of the target flexible DC power system obtained according to the received data information, and correct it, and upload the data information to the modeling completion module; the modeling completion module is used to complete the final flexible DC electromagnetic transient modeling according to the received data information and the obtained correction results.

Claims

1. A flexible DC electromagnetic transient modeling method, comprising the following steps: S1. Acquire data information of the target flexible DC power system; S2. According to the data information obtained in step S1, modular modeling of the target flexible DC power system is performed based on simulation software; S3. Model the structured controller of the target flexible DC power system based on simulation software; S4. Based on the model obtained in step S2 and step S3, an electromagnetic transient simulation model of the target flexible DC power system is established; S5. Perform simulation test on the electromagnetic transient simulation model of the target flexible DC power system obtained in step S4, and make corrections; S6. According to the correction result obtained in step S5, the final flexible DC electromagnetic transient modeling is completed.

2. The flexible DC electromagnetic transient modeling method according to claim 1 is characterized in that According to the data information obtained in step S1, modular modeling of the target flexible DC power system is performed based on simulation software in step S2, which specifically includes the following steps: Based on the PSModel simulation software, the topology structure is modified according to the modeling requirements of the electromagnetic transient model; the modification includes modifying the .psm file of electrical component information, modifying the .psm file of node information, and modifying the .sub file of the converter station topology structure; Based on the PSModel simulation software, the parameters of each device are modified according to the modeling requirements of the electromagnetic transient model; the modification includes: modifying the .con file to modify the system parameters, and the system parameters include the capacity reference value, DC voltage reference value, grid-side and valve-side line voltage reference value, transformer capacity, reactance value, copper loss, number of converter valve submodules, converter valve submodule capacitance and converter valve bridge arm inductance.

3. The flexible DC electromagnetic transient modeling method according to claim 2 is characterized in that The step S3 of modeling the structured controller of the target flexible DC power system based on the simulation software specifically includes the following steps: Modeling structured controllers; Determine the control strategy of each converter station; the control strategy includes a passive control mode, a DC voltage mode and a fixed active power mode; Adjust the control system parameters: Determine whether the converter station is in constant DC voltage mode: If the converter station is in the constant DC voltage mode, the DC side line is disconnected and the active output current i d and reactive output current i q Whether it is possible to track the active current reference value i dref and reactive current reference value i qref According to the change of i dref and i qref Whether it is possible to track changes in DC voltage and reactive power or AC voltage and adjust the outer loop control parameters; If the converter station is not in the constant DC voltage mode, the DC circuit is disconnected and the constant voltage source is connected; according to the active output current i d and reactive output current i q Can it track the active current reference value i dref and reactive current reference value i qref Adjust the control parameters of the phase-locked loop and the current inner loop according to the change of According to the active current reference value i dref and reactive current reference value i qref Whether it is possible to track changes in active power and reactive power or AC side voltage and adjust the outer loop control parameters.

4. The flexible DC electromagnetic transient modeling method according to claim 3 is characterized in that The modeling of the structured controller specifically includes the following steps: A dual-loop control structure based on Park transformation is adopted to model the structured controller into a measurement unit, an outer-loop control unit, an inner-loop control unit and a valve control unit. The measuring unit includes a filtering module, a three-phase-dq conversion module, a power calculation module, a phase-locked loop module, a power synchronization loop module and a fixed angular frequency module; the output end of the filtering module is connected to the power calculation module through the three-phase-dq conversion module; at the same time, the output end of the filtering module also outputs the output signal of the measuring unit through the phase-locked loop module, the power synchronization loop module and the fixed angular frequency module; the output of the power calculation module and the output of the filtering module are also the output of the measuring unit; the output of the measuring unit is used as a key signal; The outer loop control unit includes a d-axis voltage control module, an active power control module, a DC voltage control module, a q-axis voltage control module, a five-power power control module, an AC voltage control module and a fault ride-through module; the input of the outer loop control unit is the output of the measurement unit; the outputs of the d-axis voltage control module, the active power control module and the DC voltage control module are all used as inputs of the fault ride-through module; the outputs of the q-axis voltage control module, the five-power power control module and the AC voltage control module are all used as inputs of the fault ride-through module; the output of the fault ride-through module is the output of the outer loop control unit; the output of the outer loop control unit is used as a current instruction; The inner loop control unit includes a current inner loop control module, a DC control loop module and a three-phase-dq conversion module; the input of the inner loop control unit is the output of the outer loop control unit; the output of the current inner loop control module is converted by the three-phase-dq conversion module and used as the output of the inner loop control unit; the output of the inner loop control unit is used as a voltage command; The valve control unit includes a circulating current suppression module and a sorting and pressure balancing module; the output of the circulating current suppression unit, the output of the inner loop control unit and the output of the DC control loop module are multiplied and processed by the sorting and pressure balancing module to obtain the output of the valve control unit; the output of the valve control unit is used as a trigger instruction.

5. The flexible DC electromagnetic transient modeling method according to claim 4 is characterized in that The step S4, based on the model obtained in step S2 and step S3, establishes an electromagnetic transient simulation model of the target flexible DC power system, which specifically includes the following steps: Initialize the target flexible DC power system: first start the fixed DC voltage control, then start the sending and receiving end converter stations to determine whether the constraints are met: Where P 送 is the active power output by all sending-end converter stations; P 受 The active power transmitted by all receiving converter stations; P VDC is the rated capacity of the fixed DC voltage station; If the constraints are met, the simulation is performed directly; If the constraints are not met, the unlocking sequence of the sending and receiving converter stations is modified and the constraints are checked again.

6. The flexible DC electromagnetic transient modeling method according to claim 5 is characterized in that The step S5 of performing simulation test on the electromagnetic transient simulation model of the target flexible DC power system obtained in step S4 and correcting the model specifically includes the following steps: Conduct steady-state performance test on the established electromagnetic transient simulation model of the target flexible DC power system: connect an ideal voltage source to the AC system, conduct step response test, change the active power, reactive power and DC voltage reference values, and judge whether the output active power, reactive power and established DC voltage of each converter station can meet the corresponding reference values ​​set: if not, modify the model; Conduct fault performance test on the established electromagnetic transient simulation model of the target flexible DC power system: simulate short circuit faults at the AC side access points of different converter stations to observe whether the system model can recover and operate normally after the fault; if not, modify the model.

7. A system for implementing the flexible DC electromagnetic transient modeling method according to any one of claims 1 to 6, characterized in that It includes a data acquisition module, a modular modeling module, a controller modeling module, a simulation modeling module, a model correction module and a modeling completion module; the data acquisition module, the modular modeling module, the controller modeling module, the simulation modeling module, the model correction module and the modeling completion module are connected in series in sequence; the data acquisition module is used to acquire data information of the target flexible DC power system and upload the data information to the modular modeling module; The modular modeling module is used to perform modular modeling of the target flexible DC power system based on the received data information and the acquired data information based on the simulation software, and upload the data information to the controller modeling module; The controller modeling module is used to model the structured controller of the target flexible DC power system based on the received data information and the simulation software, and upload the data information to the simulation modeling module; The simulation modeling module is used to establish an electromagnetic transient simulation model of the target flexible DC power system based on the received data information and the obtained model, and upload the data information to the model correction module; The model correction module is used to simulate and test the electromagnetic transient simulation model of the target flexible DC power system according to the received data information, and correct it, and upload the data information to the modeling completion module; The modeling completion module is used to complete the final flexible DC electromagnetic transient modeling according to the received data information and the obtained correction results.

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