Impedance measurement system and impedance measurement method of new energy grid-connected system

Abstract

The invention relates to an impedance measurement system and an impedance measurement method for a new energy grid-connected system. The impedance measurement system comprises a first measurement device, a second measurement device, a third measurement device and a control device, the control device is connected with the first measuring device, the second measuring device and the third measuring device; the fifth end of the first measuring device outputs disturbance current of a first phase; the fifth end of the second measuring device outputs disturbance current of a second phase; and the fifth end of the third measuring device outputs disturbance current of a third phase. And the control device is used for determining the impedance of the new energy grid-connected system and controlling the first measurement device, the second measurement device and the third measurement device to operate based on the disturbance current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the power grid voltage of the first phase, the power grid voltage of the second phase and the power grid voltage of the third phase. By adopting the method, the measurement effect of the impedance of the new energy grid-connected system and the reliability of the measurement result can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of impedance measurement, and in particular to an impedance measurement system and an impedance measurement method for a new energy grid-connected system. Background Art

[0002] The new energy grid-connected system refers to a system that connects the electric energy generated by new energy power generation equipment (such as solar photovoltaic panels, wind turbines, etc.) into the power grid for transmission and use. The three-phase converter for new energy grid-connected is a converter that converts the DC power generated by new energy such as solar photovoltaics into AC power and connects the AC power into the power grid.

[0003] The impedance of the renewable energy grid-connected system (i.e., the impedance of the power grid and the three-phase converter) is an important parameter for analyzing and predicting the operational stability of the renewable energy grid-connected system. When measuring the impedance of the renewable energy grid-connected system, the traditional scheme generally uses an impedance measurement system to inject disturbances of different frequencies into the renewable energy grid-connected system, and then further calculates the wide-band impedance of the system through sampling data. However, the existing impedance measurement system cannot simultaneously and accurately control the three-phase disturbance of the three-phase converter, resulting in poor measurement results and low reliability of the measurement results.

[0004] How to improve the measurement effect and reliability of the impedance of the new energy grid-connected system is still an urgent problem to be solved. Summary of the invention

[0005] Based on this, 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 impedance of the new energy grid-connected system in response to the above technical problems.

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

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

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

[0009] The third measuring device has a first end connected to the first end of the third DC capacitor, a second end connected to the second end of the third DC capacitor, a third end connected to the third phase of the three-phase converter, a fourth end connected to the fourth end of the second measuring device, and a fifth end outputting the disturbance current of the third phase; wherein the third DC capacitor is arranged 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 comprises: a sampling unit, a controller and a driver; the input end of the controller is connected to the output end of the sampling unit; the input end of the driver is connected to the output end of the controller, and the output end 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 then output system voltage and current data;

[0013] The controller is used to output a control signal according to the system voltage and current data;

[0014] The driver is used to output a driving 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] Wherein, 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 disturbance current reference value of the first phase, the disturbance current reference value of the second phase and the disturbance current reference value of the third phase;

[0016] Among them, 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 disturbance current reference value of the first phase, the disturbance current reference value of the second phase and the disturbance current reference value of 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 end of the phase-locked loop control unit is connected to the output end of the sampling unit, and the output end is connected to the input end of the DC voltage control unit; the output end of the DC voltage control unit is connected to the input end of the output disturbance control unit; the output end 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 according to the system voltage and current data;

[0020] The DC voltage control unit is used to output the voltage adjustment amount of the first DC capacitor, the voltage adjustment amount of the second DC capacitor and the voltage adjustment amount of the third DC capacitor according to 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 according to the voltage adjustment amount of the first DC capacitor, the voltage adjustment amount of the second DC capacitor, the voltage adjustment 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 end of the filter is connected to the output end of the sampling unit, and the output end is connected to the input end of the phase-locked loop module; the output end of the phase-locked loop module is connected to the input end of the phase calculation module; the output end 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 according to the system voltage and current data after filtering;

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

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

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

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

[0029] A calculation module is used to output the voltage adjustment amount of the first DC capacitor according to the first adjustment reference value and the phase information of the first phase, output the voltage adjustment 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 adjustment 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 according to a disturbance current reference value of the first phase, a disturbance current reference value of the second phase, a 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 adjustment amount of the first DC capacitor, the voltage adjustment amount of the second DC capacitor and the voltage adjustment amount of the third DC capacitor, a preset disturbance output number and a disturbance output frequency;

[0032] The inner loop control unit is used to output a second control signal according to 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 comprises: a first bridge conversion circuit and a first filtering circuit;

[0035] A first end of the first bridge conversion circuit is connected to a first end of the first DC capacitor, a second end is connected to the control device, and a third end is connected to a first end of the first filter circuit;

[0036] The second end of the first filter circuit is connected to the first phase, and the third end is connected to the fourth end of the first bridge conversion circuit;

[0037] The second measuring device comprises: a second bridge conversion circuit and a second filtering circuit;

[0038] A first end of the second bridge conversion circuit is connected to a first end of the second DC capacitor, a second end is connected to the control device, and a third end is connected to a second end of the second filter circuit;

[0039] The second end of the second filter circuit is connected to the second phase, and the third end is connected to the fourth end of the second bridge conversion circuit;

[0040] The third measuring device comprises: a third bridge conversion circuit and a third filtering circuit;

[0041] The first end of the third bridge conversion circuit is connected to the first end of the third DC capacitor, the second end is connected to the control device, and the third end is connected to the second end of the third filter circuit;

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

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

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

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

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

[0047] Acquiring a first-phase grid voltage, a second-phase grid voltage, and a third-phase grid voltage;

[0048] 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 according to 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;

[0049] The operating states of the first measuring device, the second measuring device and the third measuring device are displayed, and the obtained wide-band impedance parameters of the three-phase converter and the power grid in the new energy grid-connected system are displayed.

[0050] In a third aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the method described in the second aspect are implemented.

[0051] In a fourth aspect, the present application provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the steps of the method described in the second aspect are implemented.

[0052] The control device in the impedance measurement system provided above 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. In this way, through the control device, the three-phase disturbance of the three-phase converter can be simultaneously controlled and controlled with high precision according to the disturbance current of each phase of the three-phase converter, so that the measurement result is more reliable and more accurate. It is also possible to maintain the DC voltage balance of the three-phase converter during the disturbance output, ensure the normal operation of the three-phase converter, and reduce the negative impact of impedance measurement on the new energy grid-connected system. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0054] FIG1 is a schematic diagram of an impedance measurement system according to an embodiment;

[0055] FIG2 is a schematic diagram of a partial structure of an impedance measurement system in one embodiment;

[0056] FIG3 is a schematic diagram of a partial structure of an impedance measurement system in one embodiment;

[0057] FIG4 is a schematic diagram of a partial structure of an impedance measurement system in another embodiment;

[0058] FIG5 is a schematic diagram of a partial structure of an impedance measurement system in one embodiment;

[0059] FIG6 is a schematic diagram of a partial structure of an impedance measurement system in another embodiment;

[0060] FIG7 is a schematic diagram of a partial structure of an impedance measurement system in one embodiment;

[0061] FIG8 is a schematic flow chart of an impedance measurement method in one embodiment;

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

[0063] Description of reference numerals:

[0064] 10, impedance measurement system; 11, first measurement device; 12, second measurement device; 13, third measurement device; 14, control device;

[0065] 20, three-phase converter; 21, first DC capacitor; 22, second DC capacitor; 23, third DC capacitor;

[0066] 110, a first bridge conversion circuit; 111, a first filter circuit; 112, a first filter inductor; 113, a first filter capacitor;

[0067] 120, a second bridge conversion circuit; 121, a second filter circuit; 122, a second filter inductor; 123, a second filter capacitor;

[0068] 130, a third bridge conversion circuit; 131, a third filter circuit; 132, a third filter inductor; 133, a 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 DESCRIPTION

[0070] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0071] A new energy grid-connected system refers to a system that connects the electric energy generated by new energy power generation equipment (such as solar photovoltaic panels, wind turbines, etc.) to the power grid for transmission and use. The three-phase converter for new energy grid-connected is a converter that converts the DC power generated by new energy such as solar photovoltaics into AC power and connects the AC power to the power grid. The impedance of the new energy grid-connected system (i.e., the impedance of the power grid and the three-phase converter) is an important parameter for analyzing and predicting the operating stability of the new energy grid-connected system. When measuring the impedance of the new energy grid-connected system, the traditional scheme generally uses an impedance measurement system to inject disturbances of different frequencies into the new energy grid-connected system, and then further calculates the wide-band impedance of the system through sampling data. However, the existing impedance measurement system cannot simultaneously control the three-phase disturbance of the three-phase converter with high precision, resulting in poor measurement effect and low reliability of the measurement results.

[0072] Based on the above problems, the present application provides an impedance measurement system and an impedance measurement method for a new energy grid-connected system.

[0073] In an exemplary embodiment, as shown in FIG. 1 , the impedance measurement system 10 includes a first measurement device 11 , a second measurement device 12 , a third measurement 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 end 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 arranged on the DC side. The first DC capacitor 21 is arranged corresponding to the first phase, and the first DC capacitor 21 is arranged on the first corresponding DC side. The second DC capacitor 22 is arranged corresponding to the second phase, and the second DC capacitor 22 is arranged on the second corresponding DC side. The third DC capacitor 23 is arranged corresponding to the third phase, and the third DC capacitor 23 is arranged 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 a first end connected to the first end of the third DC capacitor 23, a second end connected to the second end of the third DC capacitor 23, a third end connected to the third phase of the three-phase converter 20, a fourth end connected to the fourth end of the second measuring device 12, and a 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 current of the first phase, the disturbance current of the second phase, and the disturbance current of the third phase 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 current of the first phase, the disturbance current of the second phase, the disturbance current of the third phase, the power grid voltage of the first phase, the power grid voltage of the second phase, and the power 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 topological structure.

[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 first measuring device 11, the second measuring device 12 and the third measuring device 13 are controlled to operate, for example, 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 are controlled. The three-phase disturbance of the three-phase converter 20 by the impedance measurement system 10 is controlled by controlling the operation of the first measuring device 11, the second measuring device 12 and the third measuring device 13. The control device 14 also determines how 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 and the disturbance current of the third phase in combination with other parameters. The other parameters are, 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 device itself (such as voltage, current, etc.).

[0083] The control device 14 may include a driver 143, a controller 142, a sampling unit 141, etc. The sampling unit 141 collects information, and the controller 142 processes the information to generate a control signal to the driver 143. The driver 143 controls the operation of the first measuring device 11, the second measuring device 12, and the third measuring device 13 under the action of the control signal.

[0084] In summary, the control device 14 in the impedance measurement system 10 provided in the present embodiment is used to determine the impedance of the new energy grid-connected system and 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 and the disturbance current of the third phase. In this way, through the control device 14, the three-phase disturbance of the three-phase converter 20 can be simultaneously controlled and controlled with high precision according to the disturbance current of each phase of the three-phase converter 20, so that the measurement result is more reliable and the accuracy is higher. It is also possible to maintain the DC voltage balance of the three-phase converter 20 when the disturbance is output, ensure the normal operation of the three-phase converter 20, and reduce the negative impact of impedance measurement on the new energy grid-connected system.

[0085] In an exemplary embodiment, as shown in FIG. 2 , the control device 14 includes: a sampling unit 141 , a controller 142 , and a driver 143 .

[0086] The input end of the controller 142 is connected to the output end of the sampling unit 141 . The input end of the driver 143 is connected to the output end of the controller 142 , and the output end 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 then output system voltage and current data.

[0088] Among them, 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 disturbance current reference value of the first phase, the disturbance current reference value of the second phase and the disturbance current reference value of the third phase.

[0089] Among them, 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 disturbance current reference value of the first phase, the disturbance current reference value of the second phase and the disturbance current reference value of the third phase.

[0090] The sampling unit 141 may include a voltage detector, a current detector, etc., which is not limited in this embodiment.

[0091] The controller 142 is used to output a control signal according to the system voltage and current data. After receiving the system voltage and current data, the controller 142 executes a corresponding control program to finally generate a control signal for each phase and input the control signal to the driver 143 .

[0092] The controller 142 may include a central processing unit (CPU), a micro control unit (MCU), etc., which is not limited in this embodiment.

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

[0094] The driver 143 may be a pulse width modulation (PWM) driver 143. The driver 143 receives control instructions from the controller 142, converts the control instructions into corresponding drive signals, and inputs them into 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 the measuring devices of each phase.

[0095] In the impedance test system provided in the present embodiment, the control device 14 includes a sampling unit 141, a controller 142 and a driver 143. The sampling unit 141 is used to output system voltage and current data after collecting electrical parameters. The controller 142 is used to output a control signal according to the system voltage and current data. The driver 143 is used to output a drive signal 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. Through the drive signal output by the driver 143, the disturbance current of each phase of the three-phase converter 20 can be controlled simultaneously and with high precision, so that the measurement result is more reliable and more accurate. It is also possible to maintain the DC voltage balance of the three-phase converter 20 when the disturbance is output, ensure the normal operation of the three-phase converter 20, and reduce the negative impact of impedance measurement on the new energy grid-connected system.

[0096] In an exemplary embodiment, as shown in FIG. 3 , 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 end of the phase-locked loop control unit 144 is connected to the output end of the sampling unit 141, and the output end is connected to the input end of the DC voltage control unit 145. The output end of the DC voltage control unit 145 is connected to the input end of the output disturbance control unit 146. The output end 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 according to the voltage and current data of the system.

[0099] As described above, the system voltage and current data 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. The input of the phase-locked loop control unit 144 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.

[0100] The phase-locked loop control unit 144 is used to lock the voltage phase of the grid connection point (access point) of the impedance measurement system 10 according to the access point voltage of the first phase, the access point voltage of the second phase and the access 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 voltage of the first phase, the access point voltage of the second phase, and the access point voltage of the third phase. SRF-PLL processing is to obtain the phase information of the voltage by converting the three-phase voltage signal into a synchronous rotating coordinate system, using the phase detection effect of the rotating coordinate transformation, and adjusting the system output frequency to synchronize the voltage vector with the D axis of the rotating coordinate system, thereby achieving phase locking. The three-phase voltage signal refers to the access point voltage of the first phase, the access point voltage of the second phase, and the access point voltage of the third phase described in this embodiment.

[0102] Before the PLL processing is performed on the three-phase voltage signal, the PLL control unit 144 may also perform filtering processing to improve the quality of the three-phase voltage signal.

[0103] The DC voltage control unit 145 is used to output the voltage adjustment amount of the first DC capacitor 21, the voltage adjustment amount of the second DC capacitor 22, and the voltage adjustment amount of the third DC capacitor 23 according to 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 adjust the voltage of the DC side capacitor of the three-phase inverter, that is, to adjust 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 according to the voltage adjustment amount of the first DC capacitor 21, the voltage adjustment amount of the second DC capacitor 22, the voltage adjustment 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 output disturbance amplitude, output disturbance phase and output disturbance frequency. The output disturbance control unit 146 controls the three-phase disturbance of the three-phase converter 20 through the control signal. The output disturbance control unit 146 can also control the adjustment speed of the three-phase disturbance of the impedance measurement system 10, and can speed up or slow down the adjustment speed of the three-phase disturbance according to actual needs.

[0106] In the impedance measurement system 10 provided in this embodiment, the driving signal output by the output disturbance control unit 146 can simultaneously control and highly accurately control the disturbance current of each phase of the three-phase converter 20, and then the three-phase disturbance of the three-phase converter 20, so that the measurement result is more reliable and more accurate. It is also possible to maintain the DC voltage balance of the three-phase converter 20 when the disturbance is output, ensure the normal operation of the three-phase converter 20, and reduce the negative impact of impedance measurement on the new energy grid-connected system.

[0107] In an exemplary embodiment, as shown in FIG. 4 , 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 end of the filter 147 is connected to the output end of the sampling unit 141, and the output end is connected to the input end of the phase-locked loop module 148. The output end of the phase-locked loop module 148 is connected to the input end of the phase calculation module 149. The output end 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 system voltage and current data to remove impurity data in the system voltage and current data, smooth 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 according to 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 according to the phase information of the first phase. Specifically, the phase calculation module 149 is used to obtain the phase information of the second phase (the phase information of the B phase) and the phase information of the third phase (the phase information of the C phase) by 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 to the DC link voltage control unit.

[0114] In the impedance measurement system 10 provided in this embodiment, the phase-locked loop control unit 144 can improve the quality of the voltage and current data of the system by filtering and processing the voltage and current data of the system, thereby improving the accuracy and reliability of the phase information of the first phase, the phase information of the second phase, and the phase information of the third phase. Indirectly improving the ability of the impedance measurement system 10 to simultaneously control and high-precision control of the three-phase disturbance of the three-phase converter 20, so that the measurement result is more reliable and more accurate.

[0115] In an exemplary embodiment, as shown in FIG. 5 , 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 end of the comparison module 150 is connected to the output end of the phase-locked loop control unit 144, and the output end is connected to the input end of the proportional-integral control module 151. The output end of the proportional-integral control module 151 is connected to the input end of the calculation module 152. The output end of the calculation module 152 is the output end of the DC voltage control unit 145.

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

[0118] The first voltage reference value, the second voltage reference value and the third voltage reference value refer to the voltage reference value of 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 may be equal and may be u ref_dcThe voltage value of the first DC capacitor 21, the voltage value of the second DC capacitor 22 and the voltage value of the third DC capacitor 23 refer to the measured voltage value of 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 Then output the first voltage comparison value.

[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 Then output the third voltage comparison value.

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

[0123] The proportional-integral control module 151 may be a proportional-integral (PI) module. PI is a control strategy widely used in the automatic control device 14. It combines proportional control and integral control to achieve precise control of the output, and is particularly suitable for systems with relatively slow changes in temperature, pressure, flow, etc. Therefore, this embodiment adopts the proportional-integral control module 151, so that the first voltage comparison value can be output as a more accurate first adjustment reference value, the second voltage comparison value can be output as a more accurate second adjustment reference value, and the third voltage comparison value can be output as a more accurate third adjustment reference value.

[0124] The calculation module 152 is configured to output a voltage adjustment amount of the first DC capacitor 21 according to the first adjustment reference value and the phase information of the first phase, output a voltage adjustment amount of the second DC capacitor 22 according to the second adjustment reference value and the phase information of the second phase, and output a voltage adjustment amount of the third DC capacitor 23 according to 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 (the θ a ) is multiplied by the voltage adjustment value of the first DC capacitor 21 (Δu dc_aThe 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 -120) to obtain the voltage adjustment value of the second DC capacitor 22 (Δu 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). a +120) to obtain the voltage adjustment value of the third DC capacitor 23 (Δu dc_c ).

[0126] This embodiment adopts the proportional-integral control module 151, which can make the first voltage comparison value output as the more accurate first adjustment reference value, the second voltage comparison value output as the more accurate second adjustment reference value, and the third voltage comparison value output as the more accurate third adjustment reference value.

[0127] In an exemplary embodiment, as shown in FIG. 6 , the first measuring device 11 includes a first bridge conversion circuit 110 and a first filtering circuit 111 .

[0128] The first end of the first bridge conversion circuit 110 is connected to the first end of the first DC capacitor 21, the second end is connected to the control device 14, and the third end is connected to the first end of the first filter circuit 111. The second end of the first filter circuit 111 is connected to the first phase, and the third end is connected to the fourth end of the first bridge conversion 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 conversion circuit 120 and a second filter circuit 121. The first end of the second bridge conversion circuit 120 is connected to the first end of the second DC capacitor 22, the second end is connected to the control device 14, and the third end is connected to the second end of the second filter circuit 121. The second end of the second filter circuit 121 is connected to the second phase, and the third end is connected to the fourth end of the second bridge conversion 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 conversion circuit 130 and a third filter circuit 131. The first end of the third bridge conversion circuit 130 is connected to the first end of the third DC capacitor 23, the second end is connected to the control device 14, and the third end is connected to the second end of the third filter circuit 131. The second end of the third filter circuit 131 is connected to the second phase, and the third end is connected to the fourth end of the third bridge conversion 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 high-frequency switching subharmonics generated by the corresponding bridge conversion circuit, thereby ensuring the quality of the disturbance current output by the impedance measurement system 10 .

[0132] The first bridge conversion circuit 110 can be composed of an H-bridge conversion circuit, and the first bridge conversion circuit 110 includes four insulated gate bipolar transistors (IGBT). In this way, the inductance and current inside the first bridge conversion circuit 110 can achieve bidirectional flow, that is, bidirectional flow of energy can be achieved. Then, through the operation of the first bridge conversion circuit 110, the voltage of the first DC capacitor 21 can be adjusted, and the voltage of the first DC capacitor 21 can be converted into a first disturbance current of a single frequency or multiple frequencies.

[0133] Similarly, the second bridge circuit 120 can be composed of an H-bridge conversion circuit, and the second bridge circuit 120 includes four insulated gate bipolar transistors (IGBT). In this way, the inductance and current inside the second bridge circuit 120 can achieve bidirectional flow, that is, bidirectional flow of energy can be achieved, and through the operation of the second bridge circuit 120, the voltage of the second DC capacitor 22 can be regulated, and the voltage of the second DC capacitor 22 can be converted into a second disturbance current of a single frequency or multiple frequencies.

[0134] Similarly, the third bridge circuit 130 can be composed of an H-bridge conversion circuit, and the third bridge circuit 130 includes four insulated gate bipolar transistors (IGBT). In this way, the inductance and current inside the third bridge circuit 130 can achieve bidirectional flow, that is, bidirectional flow of energy can be achieved, and through the action of the third bridge circuit 130, the voltage of the third DC capacitor 23 can be regulated, and the voltage of the third DC capacitor 23 can be converted into a third disturbance current of a single frequency or multiple frequencies.

[0135] In an exemplary embodiment, as shown in FIG7 , 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 control the disturbance current reference value of the first phase (as shown in FIG. refo_a ), the disturbance current reference value of the second phase (as shown in the figure refo_b ), the third phase disturbance current reference value (as shown in the figure i refo_c ), the disturbance current of the first phase (as shown in the figure o_a ), the disturbance current of the second phase (as shown in the figure o_b ), the third phase disturbance current (as shown in the figure o_c ), the voltage adjustment amount of the first DC capacitor 21 (as described above and shown in the figure Δu dc_a ), the voltage adjustment amount of the second DC capacitor 22 (as described above and shown in the figure Δu dc_b ) and the voltage regulation amount of the third DC capacitor 23 (Δu as described above and shown in the figure) dc_c ), preset disturbance output number and disturbance output frequency, and output a first control signal.

[0137] Among them, the disturbance current reference value of the first phase, the disturbance current reference value of the second phase and the disturbance current reference value of the third phase can be set according to historical experience or actual needs.

[0138] The outer loop control unit 153 can adopt a multi-proportional resonance (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, and is particularly suitable for harmonic suppression and reactive power compensation in power electronic systems. By adjusting the number n and resonance parameters of the PR controller 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 c_a ), the current of the second filter capacitor (i c_b ) and the current of the third filter capacitor (i c_c ), outputs a second control signal.

[0140] As shown in the figure, the inner loop control unit 154 can generate the second control signal by using filter capacitor current feedback. The second control signal is used to adjust the adjustment speed of the impedance measurement system 10 for the above-mentioned multiple disturbances.

[0141] It can be 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 adopts a bridge circuit (such as three half-bridge circuits) to construct the main conversion circuit of the impedance measurement system 10, and at the same time proposes a DC outer loop control strategy (implemented by the outer loop control unit 153) and a current inner loop double closed-loop control strategy (implemented by the inner loop control unit 154) of the phase-split design of the impedance measurement device, wherein the current inner loop adopts multiple PR loops to form a disturbance control outer loop, and the inner loop adopts PI control to achieve simultaneous high-precision control of multi-frequency disturbances, and the voltage outer loop adopts PI control, and the phase is introduced to achieve DC voltage stability control.

[0143] In addition, the existing devices for impedance measurement of medium and high voltage new energy grid-connected systems have complex topological structures, large volumes, and high costs. They are difficult to move directly for impedance measurement of low voltage new energy grid-connected systems, and have poor economic efficiency. The existing impedance measurement devices suitable for low voltage new energy grid-connected systems have the defect of not being able to be applied to both 380V and 690V voltage level systems at the same time, and also lack the ability to control the simultaneous output of multiple frequency disturbances. The impedance measurement system 10 provided in the above embodiment is not only suitable for low voltage new energy grid-connected systems, but also can control and adjust the simultaneous output of multiple frequency disturbances, and is suitable for both 380V and 690V voltage level systems.

[0144] In an exemplary embodiment, as shown in Fig. 8, an impedance measurement method is further provided. The impedance measurement method is applied to the impedance measurement system provided in any of the above embodiments.

[0145] The impedance measurement method includes:

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

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

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

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

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

[0151] The disturbance current of the third phase of the three-phase converter is obtained based on the third measuring device. The relevant description of the third measuring device can refer to the relevant description of the third measuring device above, which will not be repeated here.

[0152] S840: Obtain a first-phase grid voltage, a second-phase grid voltage, and a third-phase grid voltage.

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

[0154] S850. 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 according to 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.

[0155] The operation of the first measuring device, the second measuring device and the third measuring device is controlled, for example, the output disturbance amplitude, output disturbance phase and output disturbance frequency of the first measuring device, the second measuring device and the third measuring device are controlled. The three-phase disturbance of the three-phase converter by the impedance measurement system is controlled by controlling the operation of the first measuring device, the second measuring device and the third measuring device. The control device also determines how to 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 in combination with other parameters. The other parameters are, for example, the voltage of the first DC capacitor, the voltage of the second DC capacitor, the voltage of the third DC capacitor, and the electrical parameters of the measuring device itself (such as voltage, current, etc.).

[0156] S860, displaying the operating status of the first measuring device, the second measuring device and the third measuring device, and displaying the obtained wide-band impedance parameters of the three-phase converter and the power grid in the new energy grid-connected system.

[0157] The operating state can be, for example, normal operation, stopped operation, suspended operation, etc. The operating states of the first measuring device, the second measuring device, and the third measuring device can be determined by judging the outputs of the first measuring device, the second measuring device, and the third measuring device.

[0158] The broadband impedance parameter can be understood as the impedance of the above-mentioned new energy grid-connected system.

[0159] The impedance measurement method provided in the present embodiment 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, 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. According to the disturbance current of each phase of the three-phase converter, the three-phase disturbance of the three-phase converter can be simultaneously controlled and controlled with high precision, so that the measurement result is more reliable and the accuracy is higher. It is also possible to maintain the DC voltage balance of the three-phase converter during the disturbance output, ensure the normal operation of the three-phase converter, and reduce 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 embodiments described above are shown in sequence according to the instructions of the arrows, these steps are not necessarily performed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be performed in other orders. Moreover, at least a portion of the steps in the flowcharts of the embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily performed at the same time, but can be performed at different times, and the execution order of these steps or stages is not necessarily performed in sequence, but can be performed in turn or alternately with other steps or at least a portion of the steps or stages in other steps.

[0161] Based on the same inventive concept, the embodiment of the present application also provides an impedance measuring device for implementing the impedance measuring method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more impedance measuring device embodiments provided below can refer to the limitations on the impedance measuring method above, and will not be repeated here.

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

[0163] An 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 acquire the grid voltage of the first phase, the grid voltage of the second phase and the grid voltage of the third phase.

[0164] A processing module, 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 according to 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] The processing module is also used to display the operating status of the first measuring device, the second measuring device and the third measuring device, and to display the acquired broadband impedance parameters of the three-phase converter and the power grid in the new energy grid-connected system.

[0166] Each module in the above impedance measurement device can be implemented in whole or in part by software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in an electronic device in the form of hardware, or can be stored in a memory in an electronic device in the form of software, so that the processor can call and execute operations corresponding to each module.

[0167] In an exemplary embodiment, an electronic device is provided, which may be a terminal, and its internal structure diagram may be shown in FIG9. The electronic device includes a processor, a memory, an input / output interface, a communication interface, a display unit, and an input device. The processor, the memory, and the input / output interface are connected via a system bus, and the communication interface, the display unit, and the input device are connected to the system bus via the input / output interface. The processor of the electronic device is used to provide computing and control capabilities. The memory of the electronic device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the electronic device is used to exchange information between the processor and an external device. The communication interface of the electronic device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a mobile cellular network, a near field communication (NFC) or other technologies. When the computer program is executed by the processor, an impedance measurement method is implemented.

[0168] Those skilled in the art will understand that the structure shown in FIG. 9 is merely a block diagram of a partial structure related to the scheme of the present application, and does not constitute a limitation on the electronic device to which the scheme of 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 a different arrangement of components.

[0169] In an exemplary embodiment, an electronic device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the steps involved in the impedance measurement method provided in any of the above embodiments are implemented, for example, the steps are executed:

[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 three, obtaining 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 five, according to 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, 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 measuring device, the second measuring device and the third measuring device, and display the obtained wide-band 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, on which a computer program is stored. When the computer program is executed by a processor, the steps involved in the impedance measurement method provided in any of the above embodiments are implemented, for example, the steps of:

[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 three, obtaining 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 five, determining the impedance of the new energy grid-connected system and controlling the operation of the first measuring device, the second measuring device and the third measuring device according to the disturbance current of the first phase, the disturbance current of the second phase and the disturbance current of the third phase.

[0182] Step six, display the operating status of the first measuring device, the second measuring device and the third measuring device, and display the obtained wide-band impedance parameters of the three-phase converter and the power grid in the new energy grid-connected system.

[0183] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present 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. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., but are not limited to this.

[0184] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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 only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached 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 end connected to the first end of the first DC capacitor, a second end connected to the second end of the first DC capacitor, a third end connected to the first phase of the three-phase converter, and a fifth end outputting the disturbance current of the first phase; wherein the first DC capacitor is arranged corresponding to the first phase; The second measuring device has a first end connected to the first end of the second DC capacitor, a second end connected to the second end of the second DC capacitor, a third end connected to the second phase of the three-phase converter, a fourth end connected to the fourth end of the first measuring device, and a fifth end outputting the disturbance current of the second phase; wherein the second DC capacitor is arranged corresponding to the second phase; The third measuring device has a first end connected to the first end of the third DC capacitor, a second end connected to the second end of the third DC capacitor, a third end connected to the third phase of the three-phase converter, a fourth end connected to the fourth end of the second measuring device, and a fifth end outputting the disturbance current of the third phase; wherein the third DC capacitor is arranged corresponding to 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 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, 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.

2. The impedance measurement system according to claim 1, characterized in that: The control device comprises: a sampling unit, a controller and a driver; the input end of the controller is connected to the output end of the sampling unit; the input end of the driver is connected to the output end of the controller, and the output end 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 then output system voltage and current data; The controller is used to output a control signal according to the system voltage and current data; The driver is used to output a driving 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; Wherein, 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 disturbance current reference value of the first phase, the disturbance current reference value of the second phase and the disturbance current reference value of the third phase; Among them, 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 disturbance current reference value of the first phase, the disturbance current reference value of the second phase and the disturbance current reference value of the third phase.

3. The impedance measurement system according to claim 2, characterized in that: The controller comprises: a phase-locked loop control unit, a DC voltage control unit and an output disturbance control unit; The input end of the phase-locked loop control unit is connected to the output end of the sampling unit, and the output end is connected to the input end of the DC voltage control unit; the output end of the DC voltage control unit is connected to the input end of the output disturbance control unit; the output end 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 according to the system voltage and current data; The DC voltage control unit is used to output the voltage adjustment amount of the first DC capacitor, the voltage adjustment amount of the second DC capacitor and the voltage adjustment amount of the third DC capacitor according to 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 according to the voltage adjustment amount of the first DC capacitor, the voltage adjustment amount of the second DC capacitor, the voltage adjustment 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 end of the filter is connected to the output end of the sampling unit, and the output end is connected to the input end of the phase-locked loop module; the output end of the phase-locked loop module is connected to the input end of the phase calculation module; the output end 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 according to the system voltage and current data after filtering; The phase calculation module is used to determine the phase information of the second phase and the phase information of the third phase according to 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 control module and a calculation module; the input end of the comparison module is connected to the output end of the phase-locked loop control unit, and the output end is connected to the input end of the proportional-integral control module; the output end of the proportional-integral control module is connected to the input end of the calculation module; the output end of the calculation module is the output end of the DC voltage control unit; The comparison module is used to output a first voltage comparison value according to the voltage value of the first DC capacitor and the first voltage reference value, output a second voltage comparison value according to the voltage value of the second DC capacitor and the second voltage reference value, and output a third voltage comparison value according to the voltage value of the third DC capacitor and the third voltage reference value; The proportional-integral control module is used to output a first adjustment reference value according to the first voltage comparison value, output a second adjustment reference value according to the second voltage comparison value, and output a third adjustment reference value according to the third voltage comparison value; A calculation module is used to output the voltage adjustment amount of the first DC capacitor according to the first adjustment reference value and the phase information of the first phase, output the voltage adjustment 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 adjustment 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 comprises a first filter capacitor, the second measuring device comprises a second filter capacitor, and the third measuring device comprises a third filter capacitor; the output disturbance control unit comprises: an outer loop control unit and an inner loop control unit; The outer loop control unit is used to output a first control signal according to a disturbance current reference value of the first phase, a disturbance current reference value of the second phase, a 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 adjustment amount of the first DC capacitor, the voltage adjustment amount of the second DC capacitor and the voltage adjustment amount of the third DC capacitor, a preset disturbance output number and a disturbance output frequency; The inner loop control unit is used to output a second control signal according to 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 to 6, characterized in that: The first measuring device comprises: a first bridge conversion circuit and a first filtering circuit; A first end of the first bridge conversion circuit is connected to a first end of the first DC capacitor, a second end is connected to the control device, and a third end is connected to a first end of the first filter circuit; The second end of the first filter circuit is connected to the first phase, and the third end is connected to the fourth end of the first bridge conversion circuit; The second measuring device comprises: a second bridge conversion circuit and a second filtering circuit; A first end of the second bridge conversion circuit is connected to a first end of the second DC capacitor, a second end is connected to the control device, and a third end is connected to a second end of the second filter circuit; The second end of the second filter circuit is connected to the second phase, and the third end is connected to the fourth end of the second bridge conversion circuit; The third measuring device comprises: a third bridge conversion circuit and a third filtering circuit; The first end of the third bridge conversion circuit is connected to the first end of the third DC capacitor, the second end is connected to the control device, and the third end is connected to the second end of the third filter circuit; The second end of the third filter circuit is connected to the second phase, and the third end is connected to the fourth end of the third bridge conversion circuit.

8. A method for measuring impedance of a new energy grid-connected system, characterized in that: The impedance measurement system according to any one of claims 1 to 7 comprises: Acquire the disturbance current of the first phase of the three-phase converter output by the first measuring device; obtaining a disturbance current of a second phase of the three-phase converter output by a second measuring device; obtaining a disturbance current of a third phase of the three-phase converter output by a third measuring device; Acquiring a first-phase grid voltage, a second-phase grid voltage, and a third-phase grid voltage; 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 according to 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; The operating states of the first measuring device, the second measuring device and the third measuring device are displayed, and the obtained wide-band impedance parameters of the three-phase converter and the power grid in the new energy grid-connected system are displayed.

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

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to claim 8 are implemented.

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