Impedance measurement method and system for flexible DC power transmission system

Abstract

The invention relates to the technical field of flexible direct-current power transmission, and mainly discloses an impedance measurement method for a flexible direct-current power transmission system, which comprises the steps of simulation starting, simulation conversion, disturbance injection and impedance calculation. The invention further discloses an impedance measurement system for the flexible direct-current power transmission system. The impedance measurement system comprises an upper computer control unit, a real-time digital simulation unit, a flexible direct-current power transmission control unit and a disturbance injection unit. According to the flexible direct current power transmission system impedance measurement method provided by the invention, on the premise that an actual flexible direct current power transmission system controller and real disturbance injection are reserved, the power grid architecture and operation parameters are simplified, the change and setting of a main circuit and control parameters of the flexible direct current power transmission system are simplified, and the reliability of the flexible direct current power transmission system is improved. The capacity requirement of the broadband impedance measurement module is reduced, and the cost of impedance measurement of the flexible direct current power transmission system is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible direct current power transmission, and in particular to an impedance measurement method and system for a flexible direct current power transmission system. Background Art

[0002] The impedance of the flexible DC transmission system, including the impedance of the interconnected power grid and the converter station of the flexible DC transmission system, is an important parameter for analyzing and predicting the operating stability of the flexible DC transmission system. In the analysis of actual engineering problems, it is often necessary to obtain the broadband impedance of the grid side and the converter station.

[0003] In order to obtain the impedance of the flexible DC transmission system, an impedance measurement device is generally used to inject disturbances of different frequencies into the system, and then the wide-band impedance of the system is further calculated through sampling data. However, the impedance measurement cost of the actual flexible DC transmission system is high, and it is generally impossible to obtain the wide-band impedance under different parameters and scenarios. Therefore, a flexible DC transmission system impedance measurement method is needed. Using power-in-the-loop technology, the impedance measurement cost of the flexible DC transmission system is greatly reduced while retaining the actual flexible DC transmission system controller and real disturbance injection, and the flexibility and efficiency of impedance measurement are improved. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is that the impedance measurement cost of an actual flexible direct current transmission system is high, and it is generally impossible to obtain wide-band impedance under different parameters and scenarios.

[0005] The above technical problems are solved by the following technical solutions:

[0006] The present invention provides an impedance measurement method for a flexible direct current power transmission system, which comprises start-up simulation, simulation transformation, disturbance injection and impedance calculation.

[0007] In a preferred implementation of the impedance measurement method for a flexible direct current transmission system described in the present invention: starting the simulation, the real-time digital simulation unit receives and loads the parameters set by the host computer control unit, and starts the power grid model and the converter station main circuit simulation; simulation transformation, the flexible direct current transmission control unit receives the simulation data output by the real-time digital simulation unit and generates a control instruction, which is fed back to the real-time digital simulation unit; disturbance injection, the disturbance injection unit generates a disturbance signal and injects it into the real-time digital simulation unit; impedance calculation, the host computer control unit collects the power grid data after the disturbance and calculates the impedance of the power grid side and the converter station.

[0008] In a preferred implementation manner of the impedance measurement method for a flexible direct current transmission system described in the present invention: the startup simulation includes: the host computer control unit sets the voltage source, inductance and resistance parameters of the power grid model, and the main circuit parameters of the converter station through the model control module; the parameters are transmitted to the second communication module of the real-time digital simulation unit via the first communication module; the real-time digital simulation unit loads the parameters and starts the real-time simulation model including the power grid model and the flexible direct current transmission main circuit model.

[0009] In a preferred implementation of the impedance measurement method for a flexible direct current transmission system of the present invention: the power grid model includes a voltage source and an impedance network connected in series, the impedance network includes an inductor and a resistor, and is used to simulate the internal impedance characteristics of an actual power grid, and the amplitude and frequency of the voltage source and the inductor and resistor of the impedance network are dynamically adjusted by a model control module of a host computer control unit; the flexible direct current transmission main circuit model includes a sending-end converter station, a direct current line, and a receiving-end converter station, wherein the sending-end converter station is connected to the receiving-end converter station through a direct current transmission line to form a direct current transmission loop based on a modular multilevel converter, the sending end adopts a fixed direct current voltage control, the receiving end adopts a fixed active power control, and the direct current line simulates the actual resistance, inductance and capacitance characteristics.

[0010] In a preferred implementation manner of the impedance measurement method for a flexible direct current transmission system described in the present invention: the simulation transformation includes: the voltage and current signals output by the real-time digital simulation unit are transmitted to the voltage transformer and current transformer of the flexible direct current transmission control unit through the control signal input and output module; the flexible direct current transmission converter station controller generates control instructions based on the collected signals, converts them into PWM modulation waves through the drive module, and feeds back to the real-time simulation model to control the operation of the converter station.

[0011] In a preferred implementation manner of the impedance measurement method for a flexible direct current transmission system described in the present invention: the disturbance injection includes: a wide-band impedance measurement module generates a multi-band disturbance signal, which is amplified by a power amplifier and then injected into an impedance measurement access point of a real-time simulation model through a voltage signal input and output board and a current signal input and output board.

[0012] In a preferred implementation of the impedance measurement method for a flexible direct current transmission system described in the present invention: the impedance calculation includes: a data acquisition board collects the voltage and current data after the disturbance and transmits them to an impedance calculation module; the impedance calculation module performs a fast Fourier transform on the data to extract the amplitude and phase of each frequency component, and calculates the grid side impedance and the converter station impedance.

[0013] The present invention also proposes an impedance measurement system for a flexible direct current transmission system, which comprises a host computer control unit, a real-time digital simulation unit, a flexible direct current transmission control unit and a disturbance injection unit.

[0014] In a preferred embodiment of the impedance measurement system for a flexible DC power transmission system of the present invention: a host computer control unit is used to set simulation parameters, collect disturbance data and calculate impedance;

[0015] Real-time digital simulation unit, used to run real-time simulation of power grid model and flexible DC transmission main circuit model, and exchange signals with external units;

[0016] A flexible direct current transmission control unit, used for generating a converter station control instruction according to the simulation signal, and feeding back the command to the real-time digital simulation unit;

[0017] A disturbance injection unit, including a broadband impedance measurement module and a power amplifier;

[0018] The broadband impedance measurement module is used to generate a broadband disturbance signal. The power amplifier is connected to the real-time digital simulation unit and is used to amplify the broadband disturbance signal injected into the real-time digital simulation unit.

[0019] In a preferred embodiment of the impedance measurement system for a flexible DC power transmission system of the present invention: the host computer control unit includes a local workstation, a model control module, an impedance calculation module, a first communication module and a data acquisition board;

[0020] The model control module transmits parameters to the real-time digital simulation unit through the first communication module, and the data acquisition board collects the voltage and current data output by the real-time digital simulation unit and transmits them to the impedance calculation module.

[0021] In a preferred embodiment of the impedance measurement system for a flexible DC power transmission system of the present invention: the real-time digital simulation unit includes a second communication module, a digital quantity output board, a voltage signal input and output board, a current signal input and output board, a control signal input and output module and a real-time simulation model;

[0022] The second communication module is connected to the first communication module to receive the power grid model and the flexible direct current transmission main circuit parameters;

[0023] The digital quantity output board is connected to the data acquisition board to output simulated voltage and current data;

[0024] The voltage signal input and output board card and the current signal input and output board card are connected to the power amplifier to inject a disturbance signal;

[0025] The control signal input and output module is connected to the flexible DC power transmission control unit, outputs simulation signals and receives PWM control instructions;

[0026] The real-time simulation model includes a power grid model and a flexible direct current transmission main circuit model.

[0027] In a preferred embodiment of the impedance measurement system for a flexible direct current transmission system of the present invention: the flexible direct current transmission control unit includes a voltage transformer, a current transformer, a flexible direct current transmission converter station controller and a drive module;

[0028] The voltage transformer and the current transformer collect voltage and current signals output by the real-time digital simulation unit, and the converter station controller generates control instructions and converts them into PWM modulation waves through the driving module and feeds them back to the real-time digital simulation unit.

[0029] The beneficial effects of the present invention are: providing an impedance measurement method for a flexible direct current transmission system, simplifying the grid architecture and operating parameters, simplifying the change and setting of the main circuit and control parameters of the flexible direct current transmission system while retaining the actual flexible direct current transmission system controller and real disturbance injection, reducing the capacity requirement of the wide-band impedance measurement module, and reducing the cost of impedance measurement of the flexible direct current transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments of the present invention. Obviously, the drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0031] Figure 1 A flow chart of a method for measuring impedance of a flexible DC transmission system is shown;

[0032] Figure 2 A schematic diagram of an impedance measurement system for a flexible DC transmission system is shown;

[0033] Figure 3 A schematic diagram of a real-time simulation model for an impedance measurement system of a flexible DC transmission system is shown. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with specific implementation methods and drawings.

[0035] The terms used in the present invention are those general terms currently widely used in the art in consideration of the functions of the present invention, but these terms may vary according to the intention of a person of ordinary skill in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in this case, their detailed meanings will be described in the detailed description of the present invention. Therefore, the terms used in the specification should not be understood as simple names, but rather as a general description based on the meaning of the terms and the present invention.

[0036] Reference Figure 1 , Figure 2 and Figure 3 , this embodiment provides an impedance measurement method for a flexible direct current transmission system, including startup simulation, simulation transformation, disturbance injection and impedance calculation.

[0037] The startup simulation is used to build a configurable real-time simulation environment, replacing the actual physical system. The grid model parameters, including the voltage source Ug, inductance Lg and resistance Rg, are set through the model control module 12 of the host computer control unit 1. The main circuit parameters of the converter station, including the DC line impedance, are also set; the parameters are transmitted to the second communication module 21 of the real-time digital simulation unit 2 via the first communication module 14; the real-time simulation model 26 loads the transmitted parameters and starts the real-time simulation including the grid model and the flexible DC transmission main circuit model. Multi-scenario impedance measurement is supported through parameterized modeling to avoid the high cost of actual system construction.

[0038] Simulation transformation realizes the hardware-in-the-loop interaction between the actual controller 33 and the simulation model 26. The voltage and current signals output by the real-time simulation model 26 are transmitted to the voltage transformer 31 and the current transformer 32 of the flexible DC transmission control unit 3 through the control signal input and output module 25; the converter station controller 33 executes the control algorithm according to the collected signal, generates a PWM modulation wave, and feeds it back to the real-time simulation model 26 through the drive module 34 to control the operation of the converter station. It can retain the real controller logic and ensure that the control behavior is consistent with the actual project.

[0039] Disturbance injection, injecting controllable disturbance into the simulation system to stimulate impedance response, the wide-band impedance measurement module 42 generates a multi-band disturbance signal, which is amplified by the power amplifier 41 and injected into the impedance measurement access point of the real-time simulation model 26 through the voltage signal input and output board 24 and the current signal input and output board 23. The real disturbance environment is realized through power-level disturbance injection, avoiding the limitations of traditional small signal injection.

[0040] Impedance calculation, based on the extraction of wide-band impedance characteristics based on the disturbance response data, the data acquisition board 15 of the host computer control unit 1 collects the voltage and current data after the disturbance and transmits them to the impedance calculation module 13; the impedance calculation module 13 performs fast Fourier transform on the data, calculates the voltage / current amplitude ratio and phase difference at each frequency point, and obtains the grid side impedance Zg and the converter station impedance Zc, automates data processing and calculation, and improves measurement efficiency and accuracy.

[0041] Reference Figure 1 , Figure 2 and Figure 3This embodiment provides an impedance measurement method for a flexible direct current transmission system, including starting simulation, simulation transformation, disturbance injection and impedance calculation. The real-time digital simulation unit 2 runs the power grid and main circuit model, the flexible direct current transmission control unit 3 realizes the closed-loop interaction between the real controller and the simulation, the disturbance injection unit 4 injects a broadband disturbance signal, and the host computer control unit 1 completes data acquisition and impedance calculation.

[0042] The host computer control unit 1 sets the voltage source, inductance and resistance parameters of the power grid model, as well as the main circuit parameters of the converter station through the model control module 12; the parameters are transmitted to the second communication module 21 of the real-time digital simulation unit 2 via the first communication module 14; the real-time digital simulation unit 2 loads the parameters and starts the real-time simulation model 26 including the power grid model and the flexible direct current transmission main circuit model.

[0043] The power grid model includes a voltage source and an impedance network in series, the impedance network includes an inductor and a resistor, and is used to simulate the internal impedance characteristics of the actual power grid. The amplitude and frequency of the voltage source and the inductor and resistor of the impedance network are dynamically adjusted by the model control module 12 of the host computer control unit 1; the flexible DC transmission main circuit model includes a sending-end converter station, a DC line, and a receiving-end converter station, wherein the sending-end converter station is connected to the receiving-end converter station through a DC transmission line to form a DC transmission circuit based on a modular multi-level converter, the sending end adopts a fixed DC voltage control, and the receiving end adopts a fixed active power control, and the DC line simulates the actual resistance, inductance and capacitance characteristics.

[0044] The model control module 12 of the host computer control unit 1 sets the grid model parameters, including the voltage source Ug, inductance Lg, resistance Rg, and also the main circuit parameters of the converter station. The parameters are transmitted to the second communication module 21 of the real-time digital simulation unit 2 through the first communication module 14. The real-time simulation model 26 loads the parameters and starts the simulation.

[0045] The grid model is composed of a voltage source Ug and a series impedance network including an inductor Lg and a resistor Rg, simulating the internal impedance characteristics of an actual grid, wherein the amplitude and frequency of Ug, Lg and Rg parameters can be dynamically adjusted by the host computer control unit 1.

[0046] The voltage and current signals output by the real-time digital simulation unit 2 are transmitted to the voltage transformer 31 and the current transformer 32 of the flexible DC transmission control unit 3 through the control signal input and output module 25; the flexible DC transmission converter station controller 33 generates control instructions according to the collected signals, converts them into PWM modulation waves through the drive module 34, and feeds them back to the real-time simulation model 26 to control the operation of the converter station.

[0047] The control signal input and output module 25 of the real-time digital simulation unit 2 transmits the voltage and current signals output by the simulation model to the voltage transformer 31 and the current transformer 32 of the flexible DC transmission control unit 3. The converter station controller 33 generates a modulation signal based on algorithms such as real double closed-loop vector control. The drive module 34 converts it into a PWM wave and feeds it back to the real-time simulation model 26 to control the on and off of the converter station switching devices, forming a closed-loop simulation of the controller hardware in the loop.

[0048] The broadband impedance measurement module 42 generates a multi-band disturbance signal, which is amplified by the power amplifier 41 and then injected into the impedance measurement access point of the real-time simulation model 26 through the voltage signal input and output board 24 and the current signal input and output board 23 .

[0049] The wideband impedance measurement module 42 generates a multi-band disturbance signal, amplifies the disturbance voltage / current amplitude to the acceptable range of the system through the power amplifier 41, and injects it into the impedance measurement access point of the simulation model through the voltage signal input and output board 24 and the current signal input and output board 23 of the real-time digital simulation unit 2. The disturbance signal is superimposed on the original signal of the simulation model to stimulate the wideband response of the system.

[0050] The data acquisition board 15 collects the voltage and current data after the disturbance and transmits them to the impedance calculation module 13; the impedance calculation module 13 performs fast Fourier transform on the data to extract the amplitude and phase of each frequency component, and calculates the grid side impedance and the converter station impedance.

[0051] The data acquisition board 15 collects the disturbed voltage and current time domain data at a high sampling rate, transmits it to the impedance calculation module 13, performs FFT transformation, obtains the frequency domain signal, calculates the impedance amplitude and phase difference at each frequency point, and finally generates the frequency domain curves of the grid side impedance and the converter station impedance.

[0052] Reference Figure 2 and Figure 3 This embodiment provides an impedance measurement system for a flexible direct current transmission system, including a host computer control unit 1, a real-time digital simulation unit 2, a flexible direct current transmission control unit 3 and a disturbance injection unit 4.

[0053] The host computer control unit 1 comprises a local workstation 11, a model control module 12, an impedance calculation module 13, a first communication module 14 and a data acquisition board 15, which are used for test data acquisition, impedance calculation and real-time simulation system parameter setting.

[0054] The local workstation 11 is connected to a model control module 12 and an impedance calculation module 13, wherein the model control module 12 is used for the user to view and operate relevant real-time simulation model information and impedance measurement results.

[0055] The model control module 12 is connected to the local workstation 11 and the first communication module 14, and is used to control and adjust the structure and parameters of the model. For example, the impedance measurement of different grid parameters or flexible DC transmission converter stations can be carried out. The main circuit parameters or structure of the grid model and the flexible DC transmission converter station in the real-time simulation system can be adjusted through the model control module 12.

[0056] The impedance calculation module 13 is connected to the local workstation 11 and the data acquisition board 15, and is used to process the voltage and current data required for impedance measurement. Fast Fourier transform can be used to obtain the voltage, current amplitude and phase information at the measurement frequency, and the impedance of the grid side and the converter station of the flexible DC transmission system can be calculated based on this.

[0057] The first communication module 14 of the host control unit 1 is connected to the model control module 12 and the second communication module 21 of the real-time digital simulation unit 2, and is used to realize communication between the host control unit 1 and the real-time digital simulation unit 2, such as the transmission of the real-time simulation model 26 structure and parameter signals.

[0058] The host computer data acquisition board 15 is connected to the impedance calculation module 13 and the digital quantity output board 22 module in the real-time digital simulation unit 2, and is used to obtain the test data of the real-time simulation model and transmit the collected data to the impedance calculation module. For example, the voltage and current raw data required by the impedance calculation module all rely on the collection of this module.

[0059] The real-time digital simulation unit 2 includes a second communication module 21, a digital output board 22, a voltage signal input and output board 24, a current signal input and output board 23, a control signal input and output module 25 and a real-time simulation model 26, which is used to execute the constructed real-time simulation model of the flexible direct current transmission system, including a power grid model and a main circuit model of the flexible direct current transmission converter station.

[0060] The power grid model is composed of a voltage source and an impedance network in series, where the voltage source is represented by Ug, and the series impedance network includes an inductor Lg and a resistor Rg, which are used to simulate the actual power grid voltage and internal impedance, and can be adjusted according to the parameters and structures of different application requirements; the main circuit model of the flexible DC transmission system includes a sending-end converter station, a DC transmission line and a receiving-end converter station, which is used to simulate the main circuit of the flexible DC transmission system.

[0061] The control signal input and output module 25 is respectively connected to the voltage transformer 31, the current transformer 32 and the drive module 34, and is used to output the voltage and current signals of the real-time simulator model, and at the same time receive the switch drive signal from the drive module 34 in the flexible DC transmission control unit 3, so as to realize the interaction between the real-time simulation model 26 and the flexible DC transmission converter station controller 33.

[0062] The flexible direct current transmission control unit 3 is used to control the operation of the real-time simulation model of the flexible direct current transmission system. At the same time, the controller supports the modification of the control mode and control parameters to meet the impedance measurement requirements of different flexible direct current transmission systems.

[0063] The voltage transformer 31 and the current transformer 32 are connected to the control signal input and output module 25 of the real-time digital simulation unit 2 and the flexible DC transmission converter station controller 33, and are used to collect the analog voltage and current signals output by the real-time digital simulation unit 2, and transmit the sampled signals to the flexible DC transmission converter station controller 33.

[0064] The flexible DC transmission converter station controller 33 is connected to the voltage transformer 31, the current transformer 32 and the drive module 34, and is used to receive sampling signals, execute the control program of the flexible DC transmission sending-end converter station and the receiving-end converter station, and input the control instructions to the drive module 34;

[0065] The drive module 34 is connected to the flexible DC transmission converter station controller 33 and the control signal input and output module 25 of the real-time digital simulation unit 2, and is used to convert the instructions of the flexible DC transmission converter station controller 33 into switch drive signals and transmit them to the real-time digital simulation unit 2.

[0066] The disturbance injection unit 4 comprises a power amplifier 41 and a broadband impedance measurement module 42, and is used for injecting a real broadband disturbance into the flexible direct current transmission system under test.

[0067] The broadband impedance measurement module 42 is connected to the power amplifier 41 and is used to generate a broadband disturbance signal and transmit it to the power amplifier 41 to realize the injection of real disturbance in the impedance measurement of the flexible DC transmission system.

[0068] The right side of the power amplifier 41 is connected to the impedance measuring device, and the left side is connected to the voltage signal input and output board 24 and the current signal input and output board 23 of the real-time digital simulation unit 2, which are used to transmit the voltage and current signals of the access point of the impedance measuring device in the real-time simulation model 26, and at the same time transmit the disturbance signal input by the impedance measuring device to the real-time simulation model 26 of the real-time digital simulation unit 2. The real-time simulation model 26 simulates the flexible direct current transmission system after the disturbance injection intensity is injected. The above means are used to realize the wide-band impedance measurement of the flexible direct current transmission system with the disturbance power in the loop, thereby improving the accuracy of the impedance measurement of the flexible direct current transmission system.

[0069] Finally, it should be pointed out that the methods and devices described in detail above are only embodiments, and those skilled in the art can modify these embodiments in different ways without departing from the scope of the present invention.

Claims

1. An impedance measurement method for a flexible direct current transmission system, characterized in that: include, The simulation is started, and the real-time digital simulation unit (2) receives and loads the parameters set by the host computer control unit (1), and starts the simulation of the power grid model and the main circuit of the converter station; Simulation transformation, the flexible direct current transmission control unit (3) receives the simulation data output by the real-time digital simulation unit (2) and generates a control instruction, which is fed back to the real-time digital simulation unit (2); Disturbance injection, the disturbance injection unit (4) generates a disturbance signal and injects it into the real-time digital simulation unit (2); Impedance calculation: the host computer control unit (1) collects the power grid data after the disturbance and calculates the impedance of the power grid side and the converter station.

2. The impedance measurement method for a flexible DC power transmission system according to claim 1, characterized in that: The startup simulation includes: the host computer control unit (1) sets the voltage source, inductance and resistance parameters of the power grid model and the main circuit parameters of the converter station through the model control module (12); The parameters are transmitted to the second communication module (21) of the real-time digital simulation unit (2) via the first communication module (14); The real-time digital simulation unit (2) loads parameters and starts a real-time simulation model (26) including a power grid model and a flexible direct current transmission main circuit model.

3. The impedance measurement method for a flexible DC power transmission system according to claim 2, characterized in that: The power grid model comprises a voltage source and an impedance network connected in series, wherein the impedance network comprises an inductor and a resistor, and is used to simulate the internal impedance characteristics of an actual power grid, and the amplitude and frequency of the voltage source and the inductor and resistor of the impedance network are dynamically adjusted by a model control module (12) of a host computer control unit (1); The flexible DC transmission main circuit model includes a sending-end converter station, a DC line, and a receiving-end converter station, wherein the sending-end converter station is connected to the receiving-end converter station through a DC transmission line to form a DC transmission loop based on a modular multi-level converter. The sending end adopts a fixed DC voltage control, the receiving end adopts a fixed active power control, and the DC line simulates actual resistance, inductance and capacitance characteristics.

4. The impedance measurement method for a flexible DC power transmission system according to claim 3, characterized in that: The simulation transformation includes: the voltage and current signals output by the real-time digital simulation unit (2) are transmitted to the voltage transformer (31) and the current transformer (32) of the flexible direct current transmission control unit (3) through the control signal input and output module (25); The flexible direct current transmission converter station controller (33) generates a control instruction based on the collected signal, converts it into a PWM modulation wave through a driving module (34), and feeds it back to the real-time simulation model (26) to control the operation of the converter station.

5. The impedance measurement method for a flexible DC power transmission system according to claim 4, characterized in that: The disturbance injection comprises: a broadband impedance measurement module (42) generates a multi-band disturbance signal, which is amplified by a power amplifier (41) and then injected into an impedance measurement access point of a real-time simulation model (26) through a voltage signal input and output board (24) and a current signal input and output board (23).

6. The impedance measurement method for a flexible DC power transmission system according to claim 5, characterized in that: The impedance calculation includes: a data acquisition board (15) acquires the voltage and current data after the disturbance and transmits the data to an impedance calculation module (13); The impedance calculation module (13) performs fast Fourier transform on the data to extract the amplitude and phase of each frequency component, and calculates the grid side impedance and the converter station impedance.

7. An impedance measurement system for a flexible DC transmission system, characterized in that: include, A host computer control unit (1) is used to set simulation parameters, collect disturbance data and calculate impedance; A real-time digital simulation unit (2), used for running real-time simulation of a power grid model and a flexible DC transmission main circuit model, and exchanging signals with external units; A flexible direct current transmission control unit (3), used for generating a converter station control instruction according to the simulation signal, and feeding back the command to the real-time digital simulation unit (2); A disturbance injection unit (4) comprising a broadband impedance measurement module (42) and a power amplifier (41); The broadband impedance measurement module (42) is used to generate a broadband disturbance signal, and the power amplifier (41) is connected to the real-time digital simulation unit (2) and is used to amplify the broadband disturbance signal injected into the real-time digital simulation unit (2).

8. The impedance measurement system for a flexible DC power transmission system according to claim 7, characterized in that: The host computer control unit (1) comprises a local workstation (11), a model control module (12), an impedance calculation module (13), a first communication module (14) and a data acquisition board (15); The model control module (12) transmits parameters to the real-time digital simulation unit (2) via the first communication module (14), and the data acquisition board (15) acquires voltage and current data output by the real-time digital simulation unit (2) and transmits the data to the impedance calculation module (13).

9. The impedance measurement system for a flexible DC power transmission system according to claim 8, characterized in that: The real-time digital simulation unit (2) comprises a second communication module (21), a digital quantity output board (22), a voltage signal input and output board (24), a current signal input and output board (23), a control signal input and output module (25) and a real-time simulation model (26); The second communication module (21) is connected to the first communication module (14) to receive the power grid model and the flexible direct current transmission main circuit parameters; The digital quantity output board (22) is connected to the data acquisition board (15) to output simulated voltage and current data; The voltage signal input and output board (24) and the current signal input and output board (23) are connected to the power amplifier (41) to inject a disturbance signal; The control signal input and output module (25) is connected to the flexible direct current transmission control unit (3), outputs simulation signals and receives PWM control instructions; The real-time simulation model (26) comprises a power grid model and a flexible direct current transmission main circuit model.

10. The impedance measurement system for a flexible DC power transmission system according to claim 7, characterized in that: The flexible direct current transmission control unit (3) comprises a voltage transformer (31), a current transformer (32), a flexible direct current transmission converter station controller (33) and a drive module (34); The voltage transformer (31) and the current transformer (32) collect voltage and current signals output by the real-time digital simulation unit (2), and the converter station controller (33) generates a control instruction and converts it into a PWM modulation wave through a drive module (34) and feeds it back to the real-time digital simulation unit (2).

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