Impedance measurement system and method for new energy grid-connected systems

Abstract

This application relates to an impedance measurement system and method for a new energy grid-connected system, comprising: a first measuring device, a second measuring device, a third measuring device, and a control device; the control device is connected to the first, second, and third measuring devices; the fifth terminal of the first measuring device outputs the disturbance current of the first phase; the fifth terminal of the second measuring device outputs the disturbance current of the second phase; and the fifth terminal of the third measuring device outputs the disturbance current of the third phase. The control device is used to determine the impedance of the new energy grid-connected system and control the operation of the first, second, and third measuring devices based on the disturbance currents of the first, second, and third phases, the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase. This method can improve the measurement effect and reliability of the impedance of the new energy grid-connected system.

Description

Technical Field

[0001] This application relates to the field of impedance measurement technology, and in particular to an impedance measurement system and method for a new energy grid-connected system. Background Technology

[0002] A renewable energy grid-connected system refers to a system that integrates the electrical energy generated by renewable energy power generation equipment (such as solar photovoltaic panels, wind turbines, etc.) into the power grid for transmission and use. A three-phase converter for renewable energy grid connection is a device that converts direct current (DC) power generated by renewable energy sources such as solar photovoltaic power into alternating current (AC) power, and then integrates the AC power into the power grid.

[0003] The impedance of a renewable energy grid-connected system (i.e., the impedance of the grid and the three-phase converter) is a crucial parameter for analyzing and predicting the operational stability of such systems. Traditional methods for measuring the impedance of renewable energy grid-connected systems typically involve injecting disturbances of different frequencies into the system using an impedance measurement system, and then calculating the system's broadband impedance using sampled data. However, existing impedance measurement systems cannot simultaneously and precisely control the three-phase disturbances of the three-phase converter, resulting in poor measurement performance and low reliability of the measurement results.

[0004] Improving the measurement effect and reliability of the measurement results of the impedance of new energy grid-connected systems remains an urgent problem to be solved. Summary of the Invention

[0005] Therefore, it is necessary to provide an impedance measurement system, impedance measurement method, storage medium, and program product that can improve the measurement effect and reliability of the measurement results of the impedance of the new energy grid-connected system, in response to the above-mentioned technical problems.

[0006] In a first aspect, this application provides an impedance measurement system, comprising: a first measuring device, a second measuring device, a third measuring device, and a control device; the control device is connected to the first measuring device, the second measuring device, and the third measuring device.

[0007] The first measuring device has a first terminal connected to the first terminal of a first DC capacitor, a second terminal connected to the second terminal of the first DC capacitor, a third terminal connected to the first phase of a three-phase converter, and a fifth terminal outputting the disturbance current of the first phase; wherein the first DC capacitor is provided corresponding to the first phase.

[0008] The second measuring device has a first terminal connected to the first terminal of the second DC capacitor, a second terminal connected to the second terminal of the second DC capacitor, a third terminal connected to the second phase of the three-phase converter, a fourth terminal connected to the fourth terminal of the first measuring device, and a fifth terminal outputting the disturbance current of the second phase; wherein the second DC capacitor is configured corresponding to the second phase.

[0009] The third measuring device has a first terminal connected to the first terminal of the third DC capacitor, a second terminal connected to the second terminal of the third DC capacitor, a third terminal connected to the third phase of the three-phase converter, a fourth terminal connected to the fourth terminal of the second measuring device, and a fifth terminal outputting the disturbance current of the third phase; wherein, the third DC capacitor is provided corresponding to the third phase.

[0010] The control device is used to determine the impedance of the new energy grid-connected system and control the operation of the first measuring device, the second measuring device and the third measuring device based on the disturbance current of the first phase, the disturbance current of the second phase and the disturbance current of the third phase, the grid voltage of the first phase, the grid voltage of the second phase and the grid voltage of the third phase.

[0011] In one embodiment, the control device includes: a sampling unit, a controller, and a driver; the input terminal of the controller is connected to the output terminal of the sampling unit; the input terminal of the driver is connected to the output terminal of the controller, and the output terminal is connected to the first measuring device, the second measuring device, and the third measuring device.

[0012] The sampling unit is used to collect electrical parameters and output system voltage and current data;

[0013] The controller is used to output control signals based on the system voltage and current data;

[0014] The driver is configured to output a drive signal to the first measuring device, the second measuring device, and the third measuring device according to the control signal, so as to drive the first measuring device, the second measuring device, and the third measuring device to operate;

[0015] The electrical parameters include the grid voltage of the first phase, the grid voltage of the second phase, the grid voltage of the third phase, the disturbance current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the voltage of the first DC capacitor, the voltage of the second DC capacitor, the voltage of the third DC capacitor, the reference value of the disturbance current of the first phase, the reference value of the disturbance current of the second phase, and the reference value of the disturbance current of the third phase.

[0016] The system voltage and current data include the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase; the disturbance current of the first phase, the disturbance current of the second phase, and the disturbance current of the third phase; the voltage of the first DC capacitor, the voltage of the second DC capacitor, and the voltage of the third DC capacitor; and the reference values ​​of the disturbance current of the first phase, the second phase, and the third phase.

[0017] In one embodiment, the controller includes: a phase-locked loop control unit, a DC voltage control unit, and an output disturbance control unit;

[0018] The input terminal of the phase-locked loop control unit is connected to the output terminal of the sampling unit, and the output terminal is connected to the input terminal of the DC voltage control unit; the output terminal of the DC voltage control unit is connected to the input terminal of the output disturbance control unit; the output terminal of the output disturbance control unit outputs the control signal.

[0019] The phase-locked loop control unit is used to output the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase based on the system voltage and current data.

[0020] The DC voltage control unit is used to output the voltage regulation amount of the first DC capacitor, the voltage regulation amount of the second DC capacitor, and the voltage regulation amount of the third DC capacitor based on the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase.

[0021] The output disturbance control unit is used to output the control signal based on the voltage regulation amount of the first DC capacitor, the voltage regulation amount of the second DC capacitor, the voltage regulation amount of the third DC capacitor, the disturbance current of the first phase, the disturbance current of the second phase, and the disturbance current of the third phase.

[0022] In one embodiment, the phase-locked loop control unit includes: a filter, a phase-locked loop module, and a phase calculation module;

[0023] The input terminal of the filter is connected to the output terminal of the sampling unit, and the output terminal is connected to the input terminal of the phase-locked loop module; the output terminal of the phase-locked loop module is connected to the input terminal of the phase calculation module; the output terminal of the phase calculation module outputs the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase.

[0024] The phase-locked loop module is used to output the phase information of the first phase based on the filtered system voltage and current data;

[0025] The phase calculation module is used to determine the phase information of the second phase and the phase information of the third phase based on the phase information of the first phase.

[0026] In one embodiment, the DC voltage control unit includes: a comparison module, a proportional-integral (PI) control module, and a calculation module; the input terminal of the comparison module is connected to the output terminal of the phase-locked loop (PLL) control unit, and the output terminal is connected to the input terminal of the PI control module; the output terminal of the PI control module is connected to the input terminal of the calculation module; the output terminal of the calculation module is the output terminal of the DC voltage control unit.

[0027] The comparison module is used to output a first voltage comparison value based on the voltage value of the first DC capacitor and a first voltage reference value, output a second voltage comparison value based on the voltage value of the second DC capacitor and a second voltage reference value, and output a third voltage comparison value based on the voltage value of the third DC capacitor and a third voltage reference value.

[0028] The proportional-integral control module is used to output a first adjustment reference value based on the first voltage comparison value, a second adjustment reference value based on the second voltage comparison value, and a third adjustment reference value based on the third voltage comparison value.

[0029] The calculation module is used to output the voltage regulation amount of the first DC capacitor according to the first adjustment reference value and the phase information of the first phase, output the voltage regulation amount of the second DC capacitor according to the second adjustment reference value and the phase information of the second phase, and output the voltage regulation amount of the third DC capacitor according to the third adjustment reference value and the phase information of the third phase.

[0030] In one embodiment, the first measuring device includes a first filter capacitor, the second measuring device includes a second filter capacitor, and the third measuring device includes a third filter capacitor; the output disturbance control unit includes an outer loop control unit and an inner loop control unit.

[0031] The outer loop control unit is used to output a first control signal based on the disturbance current reference value of the first phase, the disturbance current reference value of the second phase, the disturbance current reference value of the third phase, the disturbance current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the voltage regulation amount of the first DC capacitor, the voltage regulation amount of the second DC capacitor and the voltage regulation amount of the third DC capacitor, the preset number of disturbance outputs and the disturbance output frequency.

[0032] The inner loop control unit is used to output a second control signal based on the current of the first filter capacitor, the current of the second filter capacitor, and the current of the third filter capacitor;

[0033] The control signal includes the first control signal and the second control signal.

[0034] In one embodiment, the first measuring device includes: a first bridge converter circuit and a first filter circuit;

[0035] The first terminal of the first bridge converter circuit is connected to the first terminal of the first DC capacitor, the second terminal is connected to the control device, and the third terminal is connected to the first terminal of the first filter circuit.

[0036] The second terminal of the first filter circuit is connected to the first phase, and the third terminal is connected to the fourth terminal of the first bridge converter circuit.

[0037] The second measuring device includes: a second bridge converter circuit and a second filter circuit;

[0038] The first terminal of the second bridge converter circuit is connected to the first terminal of the second DC capacitor, the second terminal is connected to the control device, and the third terminal is connected to the second terminal of the second filter circuit.

[0039] The second terminal of the second filter circuit is connected to the second phase, and the third terminal is connected to the fourth terminal of the second bridge converter circuit.

[0040] The third measuring device includes: a third bridge converter circuit and a third filter circuit;

[0041] The first terminal of the third bridge converter circuit is connected to the first terminal of the third DC capacitor, the second terminal is connected to the control device, and the third terminal is connected to the second terminal of the third filter circuit.

[0042] The second terminal of the third filter circuit is connected to the second phase, and the third terminal is connected to the fourth terminal of the third bridge converter circuit.

[0043] Secondly, this application provides an impedance measurement method for a new energy grid-connected system, applied to the impedance measurement system as described in the first aspect, comprising:

[0044] Obtain the disturbance current of the first phase of the three-phase converter output by the first measuring device;

[0045] Obtain the disturbance current of the second phase of the three-phase converter output by the second measuring device;

[0046] Obtain the disturbance current of the third phase of the three-phase converter output by the third measuring device;

[0047] Obtain the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase;

[0048] Based on the disturbance current of the first phase, the disturbance current of the second phase, and the disturbance current of the third phase, as well as the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase, the impedance of the new energy grid-connected system is determined, and the operation of the first measuring device, the second measuring device, and the third measuring device is controlled.

[0049] The system displays the operating status of the first, second, and third measuring devices, as well as the broadband impedance parameters of the three-phase converter and the power grid in the new energy grid-connected system.

[0050] Thirdly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the second aspect.

[0051] Fourthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the method described in the second aspect.

[0052] The control device in the impedance measurement system described above is used to determine the impedance of the renewable energy grid-connected system based on the disturbance currents of the first phase, the second phase, and the third phase, and to control the operation of the first, second, and third measuring devices. Thus, through this control device, the three-phase disturbances of the three-phase converter can be simultaneously and precisely controlled based on the disturbance currents of each phase, resulting in more reliable and accurate measurement results. It can also maintain the DC voltage balance of the three-phase converter during disturbance output, ensuring the normal operation of the three-phase converter and reducing the negative impact of impedance measurement on the renewable energy grid-connected system. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 This is a schematic diagram of an impedance measurement system in one embodiment;

[0055] Figure 2 This is a schematic diagram of a portion of the structure in an impedance measurement system in one embodiment;

[0056] Figure 3 This is a schematic diagram of a portion of the structure in an impedance measurement system in one embodiment;

[0057] Figure 4 This is a schematic diagram of a portion of the structure in the impedance measurement system in another embodiment;

[0058] Figure 5 This is a schematic diagram of a portion of the structure in an impedance measurement system in one embodiment;

[0059] Figure 6 This is a schematic diagram of a portion of the structure in the impedance measurement system in another embodiment;

[0060] Figure 7 This is a schematic diagram of a portion of the structure in an impedance measurement system in one embodiment;

[0061] Figure 8 This is a flowchart illustrating an impedance measurement method in one embodiment;

[0062] Figure 9 This is a diagram of the internal structure of an electronic device in one embodiment.

[0063] Explanation of reference numerals in the attached figures:

[0064] 10. Impedance measurement system; 11. First measuring device; 12. Second measuring device; 13. Third measuring device; 14. Control device;

[0065] 20, Three-phase converter; 21, First DC capacitor; 22, Second DC capacitor; 23, Third DC capacitor;

[0066] 110, First bridge converter circuit; 111, First filter circuit; 112, First filter inductor; 113, First filter capacitor;

[0067] 120, Second bridge converter circuit; 121, Second filter circuit; 122, Second filter inductor; 123, Second filter capacitor;

[0068] 130, Third bridge converter circuit; 131, Third filter circuit; 132, Third filter inductor; 133, Third filter capacitor;

[0069] 141, Sampling unit; 142, Controller; 143, Driver; 144, Phase-locked loop control unit; 145, DC voltage control unit; 146, Output disturbance control unit; 147, Filter; 148, Phase-locked loop module; 149, Phase calculation module; 150, Comparison module; 151, Proportional-integral control module; 152, Calculation module; 153, Outer loop control unit; 154, Inner loop control unit. Detailed Implementation

[0070] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0071] A renewable energy grid-connected system refers to a system that integrates the electrical energy generated by renewable energy power generation equipment (such as solar photovoltaic panels and wind turbines) into the power grid for transmission and use. A three-phase converter for renewable energy grid connection is a device that converts direct current (DC) energy generated by renewable energy sources such as solar photovoltaic power into alternating current (AC) energy, and then integrates this AC energy into the power grid. The impedance of a renewable energy grid-connected system (i.e., the impedance of the power grid and the three-phase converter) is a crucial parameter for analyzing and predicting the operational stability of such systems. Traditional methods for measuring the impedance of renewable energy grid-connected systems typically involve injecting disturbances of different frequencies into the system using an impedance measurement system, and then calculating the system's broadband impedance using sampled data. However, existing impedance measurement systems cannot simultaneously and precisely control the three-phase disturbances of the three-phase converter, resulting in poor measurement performance and low reliability of the measurement results.

[0072] To address the aforementioned issues, this application provides an impedance measurement system and method for a new energy grid-connected system.

[0073] In one exemplary embodiment, such as Figure 1 As shown, the impedance measurement system 10 includes a first measuring device 11, a second measuring device 12, a third measuring device 13, and a control device 14.

[0074] The three-phase converter 20 of the new energy grid-connected system includes a first phase (phase A as shown in the figure), a second phase (phase B as shown in the figure), and a third phase (phase C as shown in the figure), and is connected to the input terminal of the power grid through the first phase, the second phase, and the third phase. The three-phase converter 20 also includes a first DC capacitor 21, a second DC capacitor 22, and a third DC capacitor 23 disposed on the DC side. The first DC capacitor 21 is disposed on the first corresponding DC side. The second DC capacitor 22 is disposed on the second corresponding DC side. The third DC capacitor 23 is disposed on the third corresponding DC side.

[0075] The first measuring device 11 has a first end connected to the first end of the first DC capacitor 21, a second end connected to the second end of the first DC capacitor 21, a third end connected to the first phase of the three-phase converter 20, and a fifth end outputting the disturbance current of the first phase.

[0076] The second measuring device 12 has a first end connected to the first end of the second DC capacitor 22, a second end connected to the second end of the second DC capacitor 22, a third end connected to the second phase of the three-phase converter 20, a fourth end connected to the fourth end of the first measuring device 11, and a fifth end outputting the disturbance current of the second phase.

[0077] The third measuring device 13 has its first end connected to the first end of the third DC capacitor 23, its second end connected to the second end of the third DC capacitor 23, its third end connected to the third phase of the three-phase converter 20, its fourth end connected to the fourth end of the second measuring device 12, and its fifth end outputting the disturbance current of the third phase.

[0078] That is, the first measuring device 11 outputs the disturbance current of the first phase, the second measuring device 12 outputs the disturbance current of the second phase, and the third measuring device 13 outputs the disturbance current of the third phase. The disturbance currents of the first, second, and third phases are used to measure the impedance of the power grid and the three-phase converter 20. The control device 14 is used to determine the impedance of the new energy grid-connected system based on the disturbance currents of the first, second, and third phases, the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase.

[0079] The first measuring device 11, the second measuring device 12, and the third measuring device 13 have the same topology.

[0080] The first measuring device 11 may include a bridge circuit, a filter circuit, etc., the second measuring device 12 may include a bridge circuit, a filter circuit, etc., and the third measuring device 13 may include a bridge circuit, a filter circuit, etc.

[0081] The control device 14 is used to control the operation of the first measuring device 11, the second measuring device 12 and the third measuring device 13 based on the disturbance current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the grid voltage of the first phase, the grid voltage of the second phase and the grid voltage of the third phase.

[0082] The control device 14 controls the operation of the first measuring device 11, the second measuring device 12, and the third measuring device 13, for example, by controlling the output disturbance amplitude, output disturbance phase, and output disturbance frequency of the first measuring device 11, the second measuring device 12, and the third measuring device 13. By controlling the operation of the first measuring device 11, the second measuring device 12, and the third measuring device 13, the three-phase disturbance of the impedance measurement system 10 is controlled. Based on the disturbance current of the first phase, the disturbance current of the second phase, and the disturbance current of the third phase, the control device 14, in conjunction with other parameters, determines how to control the operation of the first measuring device 11, the second measuring device 12, and the third measuring device 13. These other parameters include, for example, the voltage of the first DC capacitor 21, the voltage of the second DC capacitor 22, the voltage of the third DC capacitor 23, and the electrical parameters of the measuring devices themselves (such as voltage, current, etc.).

[0083] The control device 14 may include a driver 143, a controller 142, a sampling unit 141, etc. Information is collected by the sampling unit 141, and after the controller 142 processes the information, a control signal is generated and sent to the driver 143. Under the action of the control signal, the driver 143 controls the operation of the first measuring device 11, the second measuring device 12, and the third measuring device 13.

[0084] In summary, the control device 14 in the impedance measurement system 10 provided in this embodiment is used to determine the impedance of the new energy grid-connected system based on the disturbance current of the first phase, the disturbance current of the second phase, and the disturbance current of the third phase, and to control the operation of the first measuring device 11, the second measuring device 12, and the third measuring device 13. Thus, through the control device 14, the three-phase disturbances of the three-phase converter 20 can be simultaneously and precisely controlled according to the disturbance currents of each phase, making the measurement results more reliable and accurate. It can also maintain the DC voltage balance of the three-phase converter 20 during disturbance output, ensuring the normal operation of the three-phase converter 20 and reducing the negative impact of impedance measurement on the new energy grid-connected system.

[0085] In one exemplary embodiment, such as Figure 2 As shown, the control device 14 includes a sampling unit 141, a controller 142, and a driver 143.

[0086] The input terminal of the controller 142 is connected to the output terminal of the sampling unit 141. The input terminal of the driver 143 is connected to the output terminal of the controller 142, and the output terminal is connected to the first measuring device 11, the second measuring device 12, and the third measuring device 13.

[0087] The sampling unit 141 is used to collect electrical parameters and output system voltage and current data.

[0088] The electrical parameters include the grid voltage of the first phase, the grid voltage of the second phase, the grid voltage of the third phase, the disturbance current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the voltage of the first DC capacitor 21, the voltage of the second DC capacitor 22, the voltage of the third DC capacitor 23, the reference value of the disturbance current of the first phase, the reference value of the disturbance current of the second phase, and the reference value of the disturbance current of the third phase.

[0089] The system voltage and current data include the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase, the disturbance current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the voltage of the first DC capacitor, the voltage of the second DC capacitor, the voltage of the third DC capacitor, the reference value of the disturbance current of the first phase, the reference value of the disturbance current of the second phase, and the reference value of the disturbance current of the third phase.

[0090] The sampling unit 141 may include a voltage detector, a current detector, etc., but this embodiment does not limit it.

[0091] The controller 142 is used to output control signals based on the system voltage and current data. After receiving the system voltage and current data, the controller 142 executes the corresponding control program, ultimately generating control signals for each phase, and inputs the control signals to the driver 143.

[0092] The controller 142 may include a central processing unit (CPU), a micro control unit (MCU), etc., but this embodiment does not limit it.

[0093] The driver 143 is used to output drive signals to the first measuring device 11, the second measuring device 12 and the third measuring device 13 to drive the first measuring device 11, the second measuring device 12 and the third measuring device 13 to operate.

[0094] The driver 143 can be a pulse-width modulation (PWM) driver 143. The driver 143 receives control commands from the controller 142 and converts the control commands into corresponding drive signals, which are then input to the measuring devices of each phase (i.e., the first measuring device 11, the second measuring device 12, and the third measuring device 13). The drive signals determine the operating state of each measuring device.

[0095] In the impedance testing system provided in this embodiment, the control device 14 includes a sampling unit 141, a controller 142, and a driver 143. The sampling unit 141 collects electrical parameters and outputs system voltage and current data. The controller 142 outputs control signals based on the system voltage and current data. The driver 143 outputs drive signals to the first measuring device 11, the second measuring device 12, and the third measuring device 13 to drive their operation. Through the drive signals output by the driver 143, simultaneous and high-precision control of the three-phase disturbances of the three-phase converter 20 can be achieved based on the disturbance currents of each phase, resulting in more reliable and accurate measurement results. Furthermore, it can maintain the DC voltage balance of the three-phase converter 20 during disturbance output, ensuring the normal operation of the three-phase converter 20 and reducing the negative impact of impedance measurement on the new energy grid-connected system.

[0096] In one exemplary embodiment, such as Figure 3As shown, the controller 142 includes: a phase-locked loop control unit 144, a DC voltage control unit 145, and an output disturbance control unit 146.

[0097] The input terminal of the phase-locked loop control unit 144 is connected to the output terminal of the sampling unit 141, and its output terminal is connected to the input terminal of the DC voltage control unit 145. The output terminal of the DC voltage control unit 145 is connected to the input terminal of the output disturbance control unit 146. The output terminal of the output disturbance control unit 146 outputs the control signal.

[0098] The phase-locked loop control unit 144 is used to output the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase based on the voltage and current data of the system.

[0099] As described above, the system voltage and current data includes the access point voltage of the first measuring device 11 connected to the first phase, the access point voltage of the second measuring device 12 connected to the second phase, and the access point voltage of the third measuring device 13 connected to the third phase. The inputs of the phase-locked loop control unit 144 include the access point voltage of the first measuring device 11 connected to the first phase, the access point voltage of the second measuring device 12 connected to the second phase, and the access point voltage of the third measuring device 13 connected to the third phase.

[0100] The phase-locked loop control unit 144 is used to lock the voltage phase of the connection point (connection point) of the impedance measurement system 10 based on the connection point voltage of the first phase, the connection point voltage of the second phase, and the connection point voltage of the third phase. The voltage phase includes the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase.

[0101] The phase-locked loop control unit 144 can perform synchronous reference frame phase-locked loop (SRF-PLL) processing on the access point voltages of the first phase, the second phase, and the third phase. SRF-PLL processing involves converting the three-phase voltage signals into a synchronous rotating coordinate system, utilizing the phase detection effect of the rotating coordinate transformation to obtain the phase information of the voltages, and adjusting the system output frequency to keep the voltage vector synchronized with the D-axis of the rotating coordinate system, thereby achieving phase locking. The three-phase voltage signals refer to the access point voltages of the first phase, the second phase, and the third phase as described in this embodiment.

[0102] Before performing SRF-PLL processing on the three-phase voltage signal, the phase-locked loop control unit 144 can also perform filtering to improve the quality of the three-phase voltage signal.

[0103] The DC voltage control unit 145 is used to output the voltage regulation amount of the first DC capacitor 21, the voltage regulation amount of the second DC capacitor 22, and the voltage regulation amount of the third DC capacitor 23 based on the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase. The DC voltage control unit 145 is used to regulate the voltage of the DC-side capacitors of the three-phase inverter, specifically the voltage of the first DC capacitor 21, the voltage of the second DC capacitor 22, and the voltage of the third DC capacitor 23.

[0104] The output disturbance control unit 146 is used to output the control signal based on the voltage regulation amount of the first DC capacitor 21, the voltage regulation amount of the second DC capacitor 22, the voltage regulation amount of the third DC capacitor 23, the disturbance current of the first phase, the disturbance current of the second phase, and the disturbance current of the third phase.

[0105] The control signal is used to control the amplitude, phase, and frequency of the output disturbance. The output disturbance control unit 146 uses this control signal to control the three-phase disturbance of the three-phase converter 20. The output disturbance control unit 146 can also control the adjustment speed of the impedance measurement system 10 for the three-phase disturbance, allowing for adjustments that can be accelerated or decelerated as needed.

[0106] In the impedance measurement system 10 provided in this embodiment, the drive signal output by the output disturbance control unit 146 enables simultaneous and high-precision control of the three-phase disturbance of the three-phase converter 20 based on the disturbance current of each phase, resulting in more reliable and accurate measurement results. It can also maintain the DC voltage balance of the three-phase converter 20 during disturbance output, ensuring the normal operation of the three-phase converter 20 and reducing the negative impact of impedance measurement on the new energy grid-connected system.

[0107] In one exemplary embodiment, such as Figure 4 As shown, the phase-locked loop control unit 144 includes: a filter 147, a phase-locked loop module 148, and a phase calculation module 149.

[0108] The input terminal of the filter 147 is connected to the output terminal of the sampling unit 141, and the output terminal is connected to the input terminal of the phase-locked loop module 148. The output terminal of the phase-locked loop module 148 is connected to the input terminal of the phase calculation module 149. The output terminal of the phase calculation module 149 outputs the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase.

[0109] The filter 147 is used to filter the voltage and current data of the system to remove impurities from the system voltage and current data, smooth out the typical data, and improve the quality of the system voltage and current data.

[0110] The phase-locked loop module 148 is used to output the phase information of the first phase based on the filtered system voltage and current data. The phase-locked loop module 148 is used to perform SRF-PLL processing on the filtered system voltage and current data to lock the phase information of the first phase (phase information of phase A).

[0111] The phase calculation module 149 is used to determine the phase information of the second phase and the phase information of the third phase based on the phase information of the first phase. Specifically, the phase calculation module 149 is used to obtain the phase information of the second phase (phase information of phase B) and the phase information of the third phase (phase information of phase C) through angle conversion.

[0112] For example, the phase information of the first phase is θ a Then the phase information of the second phase is θ. a -120, the phase information of the third phase is θ a +120.

[0113] The phase calculation module 149 inputs the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase into the DC-side voltage control unit.

[0114] In the impedance measurement system 10 provided in this embodiment, the phase-locked loop control unit 144 improves the quality of the system's voltage and current data by filtering it, thereby enhancing the accuracy and reliability of the phase information of the first phase, the second phase, and the third phase. This indirectly improves the impedance measurement system 10's ability to simultaneously and precisely control the three-phase disturbances of the three-phase converter 20, resulting in more reliable and accurate measurement results.

[0115] In one exemplary embodiment, such as Figure 5 As shown, the DC voltage control unit 145 includes: a comparison module 150, a proportional-integral control module 151, and a calculation module 152.

[0116] The input terminal of the comparison module 150 is connected to the output terminal of the phase-locked loop control unit 144, and its output terminal is connected to the input terminal of the proportional-integral control module 151. The output terminal of the proportional-integral control module 151 is connected to the input terminal of the calculation module 152. The output terminal of the calculation module 152 is the output terminal of the DC voltage control unit 145.

[0117] The comparison module 150 is used to output a first voltage comparison value based on the voltage value of the first DC capacitor 21 and a first voltage reference value, output a second voltage comparison value based on the voltage value of the second DC capacitor 22 and a second voltage reference value, and output a third voltage comparison value based on the voltage value of the third DC capacitor 23 and a third voltage reference value.

[0118] Wherein, the first voltage reference value, the second voltage reference value, and the third voltage reference value refer to the voltage reference values ​​on the DC side of the three-phase converter 20. The first voltage reference value, the second voltage reference value, and the third voltage reference value can be equal, and all can be u. ref_dc The voltage values ​​of the first DC capacitor 21, the second DC capacitor 22, and the third DC capacitor 23 refer to the measured voltage values ​​on the DC side of the three-phase converter 20. The voltage value of the first DC capacitor 21 can be u. dc_a The voltage value of the second DC capacitor 22 can be u. dc_b The voltage value of the third DC capacitor 23 can be u. dc_c .

[0119] The comparison module 150 compares u dc_a and u ref_dc The first voltage comparison value is then output.

[0120] The comparison module 150 compares u dc_b and u ref_dc Then output the second voltage comparison value.

[0121] The comparison module 150 compares u dc_c and u ref_dc The third voltage comparison value is then output.

[0122] The proportional-integral control module 151 is used to output a first adjustment reference value based on the first voltage comparison value, output a second adjustment reference value based on the second voltage comparison value, and output a third adjustment reference value based on the third voltage comparison value.

[0123] The proportional-integral (PI) control module 151 can be a proportional-integral (PI) module. PI is a control strategy widely used in automatic control devices 14. It achieves precise control of the output by combining proportional control and integral control, and is particularly suitable for systems where temperature, pressure, flow rate, and other parameters change slowly. Therefore, by using the PI control module 151 in this embodiment, the first voltage comparison value output can be a more accurate first adjustment reference value, the second voltage comparison value output can be a more accurate second adjustment reference value, and the third voltage comparison value output can be a more accurate third adjustment reference value.

[0124] The calculation module 152 is used to output the voltage regulation amount of the first DC capacitor 21 based on the first adjustment reference value and the phase information of the first phase. It also outputs the voltage regulation amount of the second DC capacitor 22 based on the second adjustment reference value and the phase information of the second phase. Finally, it outputs the voltage regulation amount of the third DC capacitor 23 based on the third adjustment reference value and the phase information of the third phase.

[0125] Specifically, the calculation module 152 is used to calculate the first adjustment reference value and the phase information of the first phase (as described above, θ) a Multiplying these values ​​yields the voltage regulation of the first DC capacitor 21 (Δu as shown in the figure). dc_a The calculation module 152 is used to calculate the second adjustment reference value and the phase information of the second phase (as described above, θ). a Multiplying by -120 gives the voltage regulation of the second DC capacitor 22 (Δu as shown in the figure). dc_b The calculation module 152 is used to calculate the third adjustment reference value and the phase information of the third phase (as described above, θ). a Multiplying by +120 gives the voltage regulation of the third DC capacitor 23 (Δu as shown in the figure). dc_c ).

[0126] In this embodiment, the proportional-integral control module 151 is used to make the first voltage comparison value output as a more accurate first adjustment reference value, the second voltage comparison value output as a more accurate second adjustment reference value, and the third voltage comparison value output as a more accurate third adjustment reference value.

[0127] In one exemplary embodiment, such as Figure 6 As shown, the first measuring device 11 includes a first bridge converter circuit 110 and a first filter circuit 111.

[0128] The first terminal of the first bridge converter circuit 110 is connected to the first terminal of the first DC capacitor 21, the second terminal is connected to the control device 14, and the third terminal is connected to the first terminal of the first filter circuit 111. The second terminal of the first filter circuit 111 is connected to the first phase, and the third terminal is connected to the fourth terminal of the first bridge converter circuit 110. The first filter circuit 111 may include a first filter inductor 112 and a first filter capacitor 113 as shown in the figure.

[0129] The second measuring device 12 includes a second bridge converter circuit 120 and a second filter circuit 121. The first terminal of the second bridge converter circuit 120 is connected to the first terminal of the second DC capacitor 22, the second terminal is connected to the control device 14, and the third terminal is connected to the second terminal of the second filter circuit 121. The second terminal of the second filter circuit 121 is connected to the second phase, and the third terminal is connected to the fourth terminal of the second bridge converter circuit 120. The second filter circuit 121 may include a second filter inductor 122 and a second filter capacitor 123 as shown in the figure.

[0130] The third measuring device 13 includes a third bridge converter circuit 130 and a third filter circuit 131. The first terminal of the third bridge converter circuit 130 is connected to the first terminal of the third DC capacitor 23, the second terminal is connected to the control device 14, and the third terminal is connected to the second terminal of the third filter circuit 131. The second terminal of the third filter circuit 131 is connected to the second phase, and the third terminal is connected to the fourth terminal of the third bridge converter circuit 130. The third filter circuit 131 may include a third filter inductor 132 and a third filter capacitor 133 as shown in the figure.

[0131] The first filter circuit 111, the second filter circuit 121 and the third filter circuit 131 all adopt an LCL filter structure, which can filter out the high-frequency switching subharmonics generated by the corresponding bridge converter circuit, and ensure the quality of the disturbance current output by the impedance measurement system 10.

[0132] The first bridge converter circuit 110 can be constructed from an H-bridge converter circuit, which includes four insulated gate bipolar transistors (IGBTs). Thus, the inductance and current within the first bridge converter circuit 110 can flow bidirectionally, enabling bidirectional energy flow. Furthermore, through the operation of the first bridge converter circuit 110, the voltage of the first DC capacitor 21 can be regulated, and the voltage of the first DC capacitor 21 can be converted into a first disturbance current of single or multiple frequencies.

[0133] Similarly, the second bridge circuit 120 can be constructed from an H-bridge converter circuit, which includes four insulated-gate bipolar transistors (IGBTs). Thus, the inductance and current within the second bridge circuit 120 can flow bidirectionally, enabling bidirectional energy flow. Furthermore, the operation of the second bridge circuit 120 can regulate the voltage of the second DC capacitor 22 and convert its voltage into a second disturbance current of single or multiple frequencies.

[0134] Similarly, the third bridge circuit 130 can be constructed from an H-bridge converter circuit, which includes four insulated-gate bipolar transistors (IGBTs). Thus, the inductance and current within the third bridge circuit 130 can flow bidirectionally, enabling bidirectional energy flow. Furthermore, the operation of the third bridge circuit 130 can regulate the voltage of the third DC capacitor 23 and convert its voltage into a single or multiple frequency third disturbance current.

[0135] In one exemplary embodiment, such as Figure 7 As shown, when the first measuring device 11 includes a first filter capacitor 113, the second measuring device 12 includes a second filter capacitor 123, and the third measuring device 13 includes a third filter capacitor 133, the output disturbance control unit 146 includes an outer loop control unit 153 and an inner loop control unit 154.

[0136] The outer loop control unit 153 is used to determine the disturbance current reference value of the first phase (as shown in the figure). refo_a The reference value of the disturbance current of the second phase (as shown in the figure i) refo_b The reference value of the disturbance current of the third phase (as shown in the figure). refo_c The disturbance current of the first phase (as shown in the figure i) o_a The disturbance current of the second phase (as shown in the figure i) o_b The disturbance current of the third phase (as shown in the figure i) o_c The voltage regulation of the first DC capacitor 21 (as described above and shown in the figure, Δu) dc_a The voltage regulation of the second DC capacitor 22 (as described above and shown in the figure, Δu) dc_b The voltage regulation of the third DC capacitor 23 (as described above and shown in the figure, Δu) and the voltage regulation of the third DC capacitor 23 dc_c The system outputs the first control signal based on the preset number of disturbance outputs and disturbance output frequency.

[0137] The reference values ​​for the disturbance current of the first phase, the second phase, and the third phase can be set based on historical experience or actual needs.

[0138] The outer loop control unit 153 can adopt a multi-proportional resonant (PR) control structure as shown in the figure, that is, it includes multiple PR controllers 142. The PR controller 142 is a control strategy for accurately tracking AC signals, particularly suitable for harmonic suppression and reactive power compensation in power electronic systems. By adjusting the number n and resonant parameters of the PR controllers 142, accurate control of multiple disturbances (i.e., the first disturbance current, the second disturbance current, and the third disturbance current) can be achieved.

[0139] The inner loop control unit 154 is used to determine the current (i) of the first filter capacitor. c_a The current of the second filter capacitor (i) c_b ) and the current (i) of the third filter capacitor c_c ), outputting the second control signal.

[0140] As shown in the figure, the inner loop control unit 154 can use filter capacitor current feedback to generate the second control signal. This second control signal is used to adjust the adjustment speed of the impedance measurement system 10 to the aforementioned multiple disturbances.

[0141] It is understood that the control signal output by the output disturbance control unit 146 includes the first control signal and the second control signal.

[0142] The impedance measurement system provided in this embodiment constructs the main conversion circuit of the impedance measurement system 10 using a bridge circuit (such as three half-bridge circuits). It also proposes a DC outer loop control strategy (implemented by the outer loop control unit 153) and a current inner loop dual closed-loop control strategy (implemented by the inner loop control unit 154) for the phase-separated design of the impedance measurement device. The current inner loop uses multiple PR loops to form a disturbance control outer loop, and the inner loop uses PI control to achieve high-precision control while handling multi-frequency disturbances. The voltage outer loop uses PI control and introduces phase to achieve stable DC voltage control.

[0143] In addition, existing devices for impedance measurement in medium- and high-voltage renewable energy grid-connected systems are complex in topology, large in size, and expensive. Their direct application to impedance measurement in low-voltage renewable energy grid-connected systems is difficult due to mobility issues and poor economic efficiency. Existing impedance measurement devices for low-voltage renewable energy grid-connected systems also lack the ability to simultaneously operate on both 380V and 690V voltage levels, and further lack the control capability for simultaneous output of multi-frequency disturbances. The impedance measurement system 10 provided in the above embodiment is not only suitable for low-voltage renewable energy grid-connected systems, but also capable of controlling and adjusting the simultaneous output of multi-frequency disturbances, making it applicable to both 380V and 690V voltage levels.

[0144] In one exemplary embodiment, such as Figure 8As shown, an impedance measurement method is also provided. This impedance measurement method is applied to the impedance measurement system provided in any of the above embodiments.

[0145] This impedance measurement method includes:

[0146] S810: Obtain the disturbance current of the first phase of the three-phase converter output by the first measuring device.

[0147] The disturbance current of the first phase of the three-phase converter is obtained based on the first measuring device. A description of the first measuring device can be found above, and will not be repeated here.

[0148] S820: Obtain the disturbance current of the second phase of the three-phase converter output by the second measuring device.

[0149] The disturbance current of the second phase of the three-phase converter is obtained based on the second measuring device. A description of the second measuring device can be found above, and will not be repeated here.

[0150] S830: Obtain the disturbance current of the third phase of the three-phase converter output by the third measuring device.

[0151] The disturbance current of the third phase of the three-phase converter is obtained based on the third measuring device. A description of this third measuring device can be found above, and will not be repeated here.

[0152] S840: Obtain the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase.

[0153] The grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase can be obtained through sampling.

[0154] S850. Based on the disturbance current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase, determine the impedance of the new energy grid-connected system and control the operation of the first measuring device, the second measuring device, and the third measuring device.

[0155] The control device controls the operation of the first, second, and third measuring devices, for example, by controlling the output disturbance amplitude, output disturbance phase, and output disturbance frequency of the first, second, and third measuring devices. By controlling the operation of the first, second, and third measuring devices, the impedance measurement system controls the three-phase disturbances to the three-phase converter. Based on the disturbance currents of the first, second, and third phases, and in conjunction with other parameters, the control device determines how to control the operation of the first, second, and third measuring devices. These other parameters include, for example, the voltages of the first, second, and third DC capacitors, and the electrical parameters of the measuring devices themselves (such as voltage and current).

[0156] S860 displays the operating status of the first, second, and third measuring devices, as well as the broadband impedance parameters of the three-phase converter and the power grid in the new energy grid-connected system.

[0157] The operating status includes, for example, normal operation, stopped operation, or aborted operation. The operating status of the first measuring device, the second measuring device, and the third measuring device can be determined by judging their outputs.

[0158] This broadband impedance parameter can be understood as the impedance of the aforementioned new energy grid-connected system.

[0159] The impedance measurement method provided in this embodiment is used to determine the impedance of a new energy grid-connected system and control the operation of the first, second, and third measuring devices based on the disturbance currents of the first, second, and third phases, the grid voltage of the first, second, and third phases, and the grid voltage of the third phase. It can simultaneously and with high precision control of the three-phase disturbances of the three-phase converter based on the disturbance currents of each phase, making the measurement results more reliable and accurate. It can also maintain the DC voltage balance of the three-phase converter during disturbance output, ensuring the normal operation of the three-phase converter and reducing the negative impact of impedance measurement on the new energy grid-connected system.

[0160] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0161] Based on the same inventive concept, this application also provides an impedance measuring device for implementing the impedance measuring method described above. The solution provided by this device is similar to the implementation described in the above method; therefore, the specific limitations in one or more impedance measuring device embodiments provided below can be found in the limitations of the impedance measuring method described above, and will not be repeated here.

[0162] In one exemplary embodiment, an impedance measurement device is provided, comprising: an acquisition module and a processing module, wherein:

[0163] The acquisition module is used to acquire the disturbance current of the first phase of the three-phase converter output by the first measuring device; acquire the disturbance current of the second phase of the three-phase converter output by the second measuring device; acquire the disturbance current of the third phase of the three-phase converter output by the third measuring device; and also to acquire the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase.

[0164] The processing module is used to determine the impedance of the new energy grid-connected system and control the operation of the first measuring device, the second measuring device and the third measuring device based on the disturbance current of the first phase, the disturbance current of the second phase and the disturbance current of the third phase, the grid voltage of the first phase, the grid voltage of the second phase and the grid voltage of the third phase.

[0165] This processing module is also used to display the operating status of the first, second, and third measuring devices, as well as to display the broadband impedance parameters of the three-phase converter and the power grid in the new energy grid-connected system.

[0166] Each module in the aforementioned impedance measurement device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of the electronic device in hardware form or independent of it, or stored in the memory of the electronic device in software form, so that the processor can call and execute the corresponding operations of each module.

[0167] In one exemplary embodiment, an electronic device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 9 As shown, this electronic device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computational and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage medium. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When the computer program is executed by the processor, it implements an impedance measurement method.

[0168] Those skilled in the art will understand that Figure 9 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the electronic device to which the present application is applied. The specific electronic device may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0169] In one exemplary embodiment, an electronic device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps involved in the impedance measurement method provided in any of the preceding embodiments, such as performing the following steps:

[0170] Step 1: Obtain the disturbance current of the first phase of the three-phase converter output by the first measuring device.

[0171] Step 2: Obtain the disturbance current of the second phase of the three-phase converter output by the second measuring device.

[0172] Step 3: Obtain the disturbance current of the third phase of the three-phase converter output by the third measuring device.

[0173] Step 4: Obtain the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase.

[0174] Step 5: Based on the disturbance current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase, determine the impedance of the new energy grid-connected system and control the operation of the first measuring device, the second measuring device, and the third measuring device.

[0175] Step six: Display the operating status of the first, second, and third measuring devices, as well as the broadband impedance parameters of the three-phase converter and the power grid in the new energy grid-connected system.

[0176] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps involved in the impedance measurement method provided in any of the preceding embodiments, such as performing the following steps:

[0177] Step 1: Obtain the disturbance current of the first phase of the three-phase converter output by the first measuring device.

[0178] Step 2: Obtain the disturbance current of the second phase of the three-phase converter output by the second measuring device.

[0179] Step 3: Obtain the disturbance current of the third phase of the three-phase converter output by the third measuring device.

[0180] Step 4: Obtain the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase.

[0181] Step 5: Based on the disturbance current of the first phase, the disturbance current of the second phase, and the disturbance current of the third phase, determine the impedance of the new energy grid-connected system and control the operation of the first measuring device, the second measuring device, and the third measuring device.

[0182] Step six: Display the operating status of the first, second, and third measuring devices, as well as the broadband impedance parameters of the three-phase converter and the power grid in the new energy grid-connected system.

[0183] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0184] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0185] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An impedance measurement system for a new energy grid-connected system, characterized in that, include: A first measuring device, a second measuring device, a third measuring device, and a control device; The control device is connected to the first measuring device, the second measuring device, and the third measuring device; The first measuring device has a first terminal connected to the first terminal of a first DC capacitor, a second terminal connected to the second terminal of the first DC capacitor, a third terminal connected to the first phase of a three-phase converter, and a fifth terminal outputting the disturbance current of the first phase; wherein the first DC capacitor is provided corresponding to the first phase. The second measuring device has a first terminal connected to the first terminal of the second DC capacitor, a second terminal connected to the second terminal of the second DC capacitor, a third terminal connected to the second phase of the three-phase converter, a fourth terminal connected to the fourth terminal of the first measuring device, and a fifth terminal outputting the disturbance current of the second phase; wherein the second DC capacitor is configured corresponding to the second phase. The third measuring device has a first terminal connected to the first terminal of the third DC capacitor, a second terminal connected to the second terminal of the third DC capacitor, a third terminal connected to the third phase of the three-phase converter, a fourth terminal connected to the fourth terminal of the second measuring device, and a fifth terminal outputting the disturbance current of the third phase; wherein, the third DC capacitor is provided corresponding to the third phase. The control device is used to determine the impedance of the new energy grid-connected system based on the disturbance current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase; and, The control device is also used to adjust the voltage of the first DC capacitor, the voltage of the second DC capacitor, and the voltage of the third DC capacitor based on the phase information of each grid voltage, so as to control the operation of the first measuring device, the second measuring device, and the third measuring device, and control the three-phase disturbance of the three-phase converter to maintain the DC voltage balance of the three-phase converter.

2. The impedance measurement system according to claim 1, characterized in that, The control device includes: a sampling unit, a controller, and a driver; the input terminal of the controller is connected to the output terminal of the sampling unit; the input terminal of the driver is connected to the output terminal of the controller, and the output terminal is connected to the first measuring device, the second measuring device, and the third measuring device. The sampling unit is used to collect electrical parameters and output system voltage and current data; The controller is used to output control signals based on the system voltage and current data; The driver is configured to output a drive signal to the first measuring device, the second measuring device, and the third measuring device according to the control signal, so as to drive the first measuring device, the second measuring device, and the third measuring device to operate; The electrical parameters include the grid voltage of the first phase, the grid voltage of the second phase, the grid voltage of the third phase, the disturbance current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the voltage of the first DC capacitor, the voltage of the second DC capacitor, the voltage of the third DC capacitor, the reference value of the disturbance current of the first phase, the reference value of the disturbance current of the second phase, and the reference value of the disturbance current of the third phase. The system voltage and current data include the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase; the disturbance current of the first phase, the disturbance current of the second phase, and the disturbance current of the third phase; the voltage of the first DC capacitor, the voltage of the second DC capacitor, and the voltage of the third DC capacitor; and the reference values ​​of the disturbance current of the first phase, the second phase, and the third phase.

3. The impedance measurement system according to claim 2, characterized in that, The controller includes: a phase-locked loop control unit, a DC voltage control unit, and an output disturbance control unit; The input terminal of the phase-locked loop control unit is connected to the output terminal of the sampling unit, and the output terminal is connected to the input terminal of the DC voltage control unit; the output terminal of the DC voltage control unit is connected to the input terminal of the output disturbance control unit; the output terminal of the output disturbance control unit outputs the control signal. The phase-locked loop control unit is used to output the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase based on the system voltage and current data. The DC voltage control unit is used to output the voltage regulation amount of the first DC capacitor, the voltage regulation amount of the second DC capacitor, and the voltage regulation amount of the third DC capacitor based on the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase. The output disturbance control unit is used to output the control signal based on the voltage regulation amount of the first DC capacitor, the voltage regulation amount of the second DC capacitor, the voltage regulation amount of the third DC capacitor, the disturbance current of the first phase, the disturbance current of the second phase, and the disturbance current of the third phase.

4. The impedance measurement system according to claim 3, characterized in that, The phase-locked loop control unit includes: a filter, a phase-locked loop module, and a phase calculation module; The input terminal of the filter is connected to the output terminal of the sampling unit, and the output terminal is connected to the input terminal of the phase-locked loop module; the output terminal of the phase-locked loop module is connected to the input terminal of the phase calculation module; the output terminal of the phase calculation module outputs the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase. The phase-locked loop module is used to output the phase information of the first phase based on the filtered system voltage and current data; The phase calculation module is used to determine the phase information of the second phase and the phase information of the third phase based on the phase information of the first phase.

5. The impedance measurement system according to claim 3, characterized in that, The DC voltage control unit includes: a comparison module, a proportional-integral (PI) control module, and a calculation module; the input terminal of the comparison module is connected to the output terminal of the phase-locked loop (PLL) control unit, and the output terminal is connected to the input terminal of the PI control module; the output terminal of the PI control module is connected to the input terminal of the calculation module; the output terminal of the calculation module is the output terminal of the DC voltage control unit. The comparison module is used to output a first voltage comparison value based on the voltage value of the first DC capacitor and a first voltage reference value, output a second voltage comparison value based on the voltage value of the second DC capacitor and a second voltage reference value, and output a third voltage comparison value based on the voltage value of the third DC capacitor and a third voltage reference value. The proportional-integral control module is used to output a first adjustment reference value based on the first voltage comparison value, a second adjustment reference value based on the second voltage comparison value, and a third adjustment reference value based on the third voltage comparison value. The calculation module is used to output the voltage regulation amount of the first DC capacitor according to the first adjustment reference value and the phase information of the first phase, output the voltage regulation amount of the second DC capacitor according to the second adjustment reference value and the phase information of the second phase, and output the voltage regulation amount of the third DC capacitor according to the third adjustment reference value and the phase information of the third phase.

6. The impedance measurement system according to claim 3, characterized in that, The first measuring device includes a first filter capacitor, the second measuring device includes a second filter capacitor, and the third measuring device includes a third filter capacitor; the output disturbance control unit includes an outer loop control unit and an inner loop control unit; The outer loop control unit is used to output a first control signal based on the disturbance current reference value of the first phase, the disturbance current reference value of the second phase, the disturbance current reference value of the third phase, the disturbance current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the voltage regulation amount of the first DC capacitor, the voltage regulation amount of the second DC capacitor and the voltage regulation amount of the third DC capacitor, the preset number of disturbance outputs and the disturbance output frequency. The inner loop control unit is used to output a second control signal based on the current of the first filter capacitor, the current of the second filter capacitor, and the current of the third filter capacitor; The control signal includes the first control signal and the second control signal.

7. The impedance measurement system according to any one of claims 1-6, characterized in that, The first measuring device includes: a first bridge converter circuit and a first filter circuit; The first terminal of the first bridge converter circuit is connected to the first terminal of the first DC capacitor, the second terminal is connected to the control device, and the third terminal is connected to the first terminal of the first filter circuit. The second terminal of the first filter circuit is connected to the first phase, and the third terminal is connected to the fourth terminal of the first bridge converter circuit. The second measuring device includes: a second bridge converter circuit and a second filter circuit; The first terminal of the second bridge converter circuit is connected to the first terminal of the second DC capacitor, the second terminal is connected to the control device, and the third terminal is connected to the second terminal of the second filter circuit. The second terminal of the second filter circuit is connected to the second phase, and the third terminal is connected to the fourth terminal of the second bridge converter circuit. The third measuring device includes: a third bridge converter circuit and a third filter circuit; The first terminal of the third bridge converter circuit is connected to the first terminal of the third DC capacitor, the second terminal is connected to the control device, and the third terminal is connected to the second terminal of the third filter circuit. The second terminal of the third filter circuit is connected to the second phase, and the third terminal is connected to the fourth terminal of the third bridge converter circuit.

8. An impedance measurement method for a new energy grid-connected system, characterized in that, Applied to the impedance measurement system as described in any one of claims 1-7, comprising: Obtain the disturbance current of the first phase of the three-phase converter output by the first measuring device; Obtain the disturbance current of the second phase of the three-phase converter output by the second measuring device; Obtain the disturbance current of the third phase of the three-phase converter output by the third measuring device; Obtain the grid voltage of the first phase, the grid voltage of the second phase, and the grid voltage of the third phase; Based on the disturbance currents of the first phase, the second phase, and the third phase, and the grid voltages of the first, second, and third phases, the impedance of the new energy grid-connected system is determined; and, Based on the phase information of each grid voltage, the voltage of the first DC capacitor, the voltage of the second DC capacitor, and the voltage of the third DC capacitor are adjusted to control the operation of the first measuring device, the second measuring device, and the third measuring device, and to control the three-phase disturbance of the three-phase converter and maintain the DC voltage balance of the three-phase converter. Control the operation of the first measuring device, the second measuring device, and the third measuring device; The system displays the operating status of the first, second, and third measuring devices, as well as the broadband impedance parameters of the three-phase converter and the power grid in the new energy grid-connected system.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method of claim 8.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the method of claim 8.

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