CN116087623A - Method and device for measuring overall impedance of new energy grid-connected system - Google Patents
Method and device for measuring overall impedance of new energy grid-connected system Download PDFInfo
- Publication number
- CN116087623A CN116087623A CN202310173496.1A CN202310173496A CN116087623A CN 116087623 A CN116087623 A CN 116087623A CN 202310173496 A CN202310173496 A CN 202310173496A CN 116087623 A CN116087623 A CN 116087623A
- Authority
- CN
- China
- Prior art keywords
- grid
- disturbance
- voltage
- frequency
- connected system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/08—Measuring resistance by measuring both voltage and current
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
The invention discloses a method and a device for measuring the overall impedance of a new energy grid-connected system. According to the invention, the voltage disturbance is applied to the grid-connected point, the disturbance voltage and the grid-connected current are recorded and analyzed, the disturbance voltage and the grid-connected current in the time domain are further converted into the frequency domain, and the integral impedance of the grid-connected system is calculated according to the frequency domain information of the disturbance voltage and the grid-connected current, so that the method can be directly used for analyzing the stability of the grid-connected system. Compared with the existing grid-connected system integral impedance measurement method, the method has the advantages that the electric quantity required to be measured is small, the number of required sensors can be reduced, and the impedance characteristic measurement cost is obviously reduced; the invention has small calculation amount of Fourier analysis, can reduce the calculation force requirement of the measuring device and improve the impedance characteristic measuring efficiency.
Description
Technical Field
The invention belongs to the technical field of impedance measurement, and relates to a method and a device for measuring the overall impedance of a new energy grid-connected system.
Background
With the development of power electronics technology, stability analysis methods based on grid-connected inverter impedance and grid impedance are widely used. How to effectively acquire the impedance of the grid-connected system and judge the stability of the grid-connected system by using the impedance is a current research hot spot.
The present impedance analysis method has two forms of impedance ratio and overall impedance, wherein the overall impedance shows the inverter impedance and the grid impedance as a whole. It is therefore critical to use it for stability analysis to obtain the overall impedance. In the existing research, the inverter impedance and the power grid impedance are respectively measured, and then the overall impedance is indirectly obtained by adding the inverter impedance and the power grid impedance, however, the oscillation phenomenon of grid-connected operation of the power generation equipment has frequency coupling characteristics, and the power grid impedance influences the inverter impedance through coupling frequency. The measuring method has the problems that a plurality of groups of voltage and current sensors and impedance calculating devices are needed for simultaneously measuring the impedance of the inverter and the impedance of the power grid
Disclosure of Invention
The invention provides a method and a device for measuring the overall impedance of a new energy grid-connected system. The method overcomes the defects of the existing measurement method, realizes direct measurement of the integral impedance of the grid-connected system, reduces the integral impedance measurement cost and improves the impedance measurement efficiency.
The aim of the invention can be achieved by the following technical scheme: a method for measuring the overall impedance of a new energy grid-connected system comprises the following steps:
step S1: for a grid-connected system, configuring a positive sequence disturbance signal;
step S2: injecting disturbance at a grid-connected point by using a harmonic injection device;
step S3: sampling and obtaining disturbance voltage and inverter output current injected with disturbance signal by using sampling equipment to obtain disturbance voltage v inj (t), inverter output current i inv (t)；
Step S4: configuring a negative sequence disturbance signal aiming at a grid-connected system;
step S5: repeating steps S2 and S3, and recording the positive sequence disturbance voltage and the negative sequence disturbance voltage as v respectively inj_p (t)、v inj_n (t) the corresponding inverter response output currents are respectively denoted as i inv_p (t)、i inv_n (t)；
Step S6: using Fourier transforms to correct sequence perturbation voltages v inj_p (t), positive sequence inverter response output current i inv_p (t), negative sequence disturbance voltage v inj_n (t), negative sequence inverter responsive to output current i inv_p (t) performing harmonic extraction, and converting harmonic components from a time domain to a frequency domain to obtain complex frequency domain harmonic components: positive sequence disturbance voltage V inj_p (s), positive sequence inverter response output current I inv_p (s) negative sequence disturbance Voltage V inj_n (s), negative sequence inverter responsive to output current I inv_n (s)；
Step S7: according to the complex frequency domain harmonic component, calculating the integral impedance Z of the grid-connected system sys (s):
The invention also provides a device for measuring the overall impedance of the grid-connected system, which comprises the following modules:
a first configuration module: configuring a positive sequence disturbance signal aiming at a grid-connected system;
and (3) an application module: applying voltage disturbance at a grid-connected point through a harmonic injection device;
and the acquisition module is used for: sampling and obtaining disturbance voltage and inverter output current injected with disturbance signal by using sampling equipment to obtain disturbance voltage v inj (t), inverter output current i inv (t)；；
And a second configuration module: configuring a negative sequence disturbance signal aiming at a grid-connected system;
and (3) repeating the module: repeating steps S2 and S3, and recording the positive sequence disturbance voltage and the negative sequence disturbance voltage as v respectively inj_p (t)、v inj_n (t) the corresponding inverter response output currents are respectively denoted as i inv_p (t)、i inv_n (t)；
And an extraction module: using Fourier transforms to correct sequence perturbation voltages v inj_p (t), positive sequence inverter response output current i inv_p (t), negative sequence disturbance voltage v inj_n (t), negative sequence inverter responsive to output current i inv_p (t) performing harmonic extraction, and converting harmonic components from a time domain to a frequency domain to obtain complex frequency domain harmonic components: positive sequence disturbance voltage V inj_p (s), positive sequence inverter response output current I inv_p (s) negative sequence disturbance Voltage V inj_n (s), negative sequence inverter responsive to output current I inv_n (s)；
The calculation module: according to the complex frequency domain harmonic component, calculating the integral impedance Z of the grid-connected system sys (s):
The invention has the beneficial effects that: compared with the existing method for indirectly measuring the integral impedance of the grid-connected system, the method directly measures the integral impedance of the grid-connected system, on one hand, the investment of sampling equipment can be reduced, and only one group of voltage and current sensors are needed; on the other hand, the calculated amount of Fourier analysis can be reduced, and the impedance measurement efficiency is improved.
Drawings
The invention is further described below with reference to the accompanying drawings.
FIG. 1 is a flow chart of the steps of the present invention;
FIG. 2 is a schematic diagram of a circuit topology and inverter control method for an example three-phase grid-tie system of the present invention;
FIG. 3 is a schematic diagram illustrating the overall impedance measurement of an exemplary three-phase grid-tie system according to the present invention;
FIG. 4 is a schematic diagram of a small signal for overall impedance measurement of an example three-phase grid-connected system according to the present invention;
FIG. 5 is a flow chart of overall impedance measurement for an example grid-tie system of the present invention;
FIG. 6 is a diagram of the positive overall impedance Bode of the grid-connected system for different grid impedances according to an embodiment of the present invention;
FIG. 7 is a diagram showing the overall negative-sequence Bode diagram of the grid-connected system for different grid impedances according to an embodiment of the present invention;
fig. 8 is a block flow diagram of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In order to enhance the understanding and appreciation for the invention, the invention will be further described with reference to the drawings and the detailed description.
Example 1: the method and the device for measuring the overall impedance of the new energy grid-connected system comprise the following specific implementation steps: s1, configuring a positive sequence disturbance signal aiming at a grid-connected system; s2, injecting disturbance at a grid-connected point by using a harmonic injection device; s3, sampling and obtaining disturbance voltage and inverter output current after disturbance signal injection by using sampling equipment to obtain disturbance voltage and inverter response output current; s4, configuring a negative sequence disturbance signal aiming at a grid-connected system; s5, repeating the steps S2 and S3, and respectively recording positive sequence disturbance voltage and negative sequence disturbance voltage and inverter response output current; s6, extracting harmonic components of disturbance signals and response currents and performing time-frequency conversion on the harmonic components; and S7, calculating the overall impedance according to the harmonic component.
The specific process of configuring the positive sequence disturbance signal comprises the following steps:
s11-determining a three-phase disturbance phase sequence, wherein the A phase leads the B phase by 120 degrees, the B phase leads the C phase by 120 degrees, and the C phase leads the A phase by 120 degrees;
s12, configuring the amplitude of the disturbance signal according to the voltage level of the access point of the inverter, and generally designing the amplitude V of the disturbance signal on the principle that the steady-state working point is not affected inj No more than 5% of the access point voltage amplitude;
s13-determining the frequency band of the impedance measurement as [ f min ,f max ]Wherein f min For measuring the lowest frequency of the frequency band, f max Measuring the highest frequency of the frequency band for the impedance;
s14-determining the number of points N of impedance measurement frequency and disturbance frequency, wherein the measurement frequency is uniformly distributed in a logarithmic coordinate system, for example, determining the frequency band of impedance measurement to be [1Hz,1000Hz ], and determining the number of points N of measurement to be 4, and the disturbance frequency to be 1Hz,10 Hz,100 Hz and 1000Hz;
s2, injecting disturbance at a grid-connected point by using a harmonic injection device, wherein the specific implementation process comprises the following steps:
s21, generating a disturbance signal by using a frequency response analyzer;
s22, amplifying the disturbance signal into disturbance voltage by using a linear power amplifier and injecting the disturbance voltage into a grid-connected system.
And S3, sampling and obtaining the disturbance voltage and the inverter output current after the disturbance signal is injected by using sampling equipment, so as to obtain the disturbance voltage and the inverter response output current. The specific implementation process is as follows:
s31, determining a sampling frequency. Sampling frequency f according to shannon's sampling theorem sample Should be greater than or equal to 2 times the maximum impedance measurement frequency f max I.e. f sample ≥2f max 。
S32-determining the duration sampling time. The frequency resolution of the fourier analysis result is inversely proportional to the duration of the sampling time, T sample Should be greater than or equal to 1/f min 。
S32, recording disturbance voltage and inverter response output current.
Step S4, the specific process of configuring the negative sequence disturbance signal comprises the following steps:
s41-determining a three-phase disturbance phase sequence, wherein the phase B is 120 degrees after the phase A, the phase C is 120 degrees after the phase B, and the phase A is 120 degrees after the phase C;
s41-configuring the amplitude of the disturbance signal according to the voltage level of the access point of the inverter, and generally designing the amplitude V of the disturbance signal on the principle that the steady-state working point is not affected inj No more than 5% of the access point voltage amplitude;
s42-determining the frequency band of the impedance measurement as [ f min ,f max ]Wherein f min For measuring the lowest frequency of the frequency band, f max Measuring the highest frequency of the frequency band for the impedance;
s43, determining the number of points N of the impedance measurement frequency and the disturbance frequency, wherein the measurement frequency is uniformly distributed in a logarithmic coordinate system, for example, determining the frequency band of impedance measurement to be [1Hz,1000Hz ], and determining the number of points N of the impedance measurement to be 4, and the disturbance frequency to be 1Hz,10 Hz,100 Hz and 1000Hz;
step S5, repeating steps S2 and S3, wherein the positive sequence disturbance voltage and the negative sequence disturbance voltage are respectively marked as v inj_p (t)、v inj_n (t) the corresponding inverter response output currents are respectively denoted as i inv_p (t)、i inv_n (t)；
S6, using Fourier transformation to correct sequence disturbance voltage v inj_p (t), positive sequence inverter response output current i inv_p (t), negative sequence disturbance voltage v inj_n (t), negative sequence inverter responsive to output current i inv_p (t) performing harmonic extraction, and converting harmonic components from a time domain to a frequency domain to obtain complex frequency domain harmonic components: positive sequence disturbance voltage V inj_p (s), positive sequence inverter response output current I inv_p (s) negative sequence disturbance Voltage V inj_n (s), negative sequence inverter responsive to output current I inv_n (s)；
S7, calculating the integral impedance Z of the grid-connected system according to the complex frequency domain harmonic component sys (s):
Application examples:
referring to fig. 1-8, a main circuit and inverter control method of a typical grid-tie system is shown in fig. 1. The direct current side of the main circuit part can be regarded as a direct current source with constant voltage, the direct current-alternating current conversion part is realized by a three-phase full-bridge inverter circuit consisting of 6 IGBTs, and the current output by the bridge arm is connected into a power grid after being filtered by an LCL. An inverter control part, wherein the voltage of the output end is input into a phase-locked loop (Phase Locked Loop, PLL) through a sampling link to obtain phase information, and the phase information is used for realizing the PARK forward conversion of the sampling current and the PARK reverse conversion of a control signal; the current control is realized by adopting PI control under the dq rotating coordinate system, and the output quantity of the controller generates a driving signal through coordinate inverse transformation and space vector modulation SVPWM to drive the IGBT.
The main parameter values of this embodiment are as follows: DC side voltage V dc =770V, inverter side filter inductance L 1 =1mh, net side filter inductance L 2 =1mh, filter capacitor C f =10uf, damping resistor R d =1.01Ω, ac busbar phase voltage effective value 220V, ac busbar voltage frequency f 0 =50hz, inverter switching frequency 16kHz, current loop controller scaling factor K pCC =4, integral coefficient K of current loop controller iCC =200, phase-locked loop controller scaling factor K pPLL =0.53, phase-locked loop controller integral coefficient K iPLL ＝31。
Since the feedback signal of the current control loop is the grid-side inductor current, the grid-connected system common connection point (Point of Common Coupling, PCC) is shown in fig. 2. Fig. 3 is a schematic diagram of overall impedance measurement of a three-phase grid-connected system. And injecting voltage disturbance in series at the PCC point through a harmonic injection device, and recording disturbance voltage and inverter response output current through sampling equipment. Fig. 4 is a schematic diagram of a small signal for overall impedance measurement of a grid-connected system, and a voltage disturbance is injected in series at a PCC point according to a conventional measurement method. And recording the voltage and the current at the two sides of the disturbance point by using a sampling device, carrying out Fourier analysis on the voltage and the current, obtaining a frequency domain signal through time-frequency conversion, respectively calculating the impedance of the inverter and the impedance of the power grid, and adding the two to obtain the integral impedance of the grid-connected system. As known from kirchhoff's voltage law, series injection voltage disturbances at PCC points can be equivalently series injection voltage disturbances at an ideal grid. According to kirchhoff current law, the inverter output current is equal to the current flowing through the grid impedance, so that voltage disturbance is injected into a PCC point, disturbance voltage and inverter output current are sampled and recorded, voltage disturbance can be equivalently injected into an ideal grid side, grid-connected system voltage and grid-connected system response current are sampled and recorded, and the overall impedance of the grid-connected system is calculated.
In the present embodiment, the disturbance voltage amplitude amp=v inj =3.11v, 1% of the grid voltage amplitude 311V. The frequency range to be measured is [1Hz,10000Hz]Measurement frequency points n=44, in order to uniformly distribute measurement frequency points in the frequency range to be measured, the measurement frequency points are: 1Hz, 2Hz, 3Hz, 4Hz, 5Hz, 6Hz, 8Hz, 9Hz, 11Hz, 13Hz, 16Hz, 19Hz, 23Hz, 28Hz, 35Hz, 42Hz, 51Hz, 62Hz, 75Hz, 91Hz, 111Hz, 135Hz, 164Hz, 199Hz, 242Hz, 294Hz, 358Hz, 435Hz, 529Hz, 644Hz, 783Hz, 953Hz, 1159Hz, 1410Hz, 1715Hz, 2086Hz, 2537Hz, 3086Hz, 3754Hz, 4567Hz, 5555Hz, 6758Hz, 8221Hz, 10000Hz. The sampling frequency of the sampling equipment is 20000Hz, the continuous sampling time is 1s, and the ith (i E [1, N)]) The positive sequence disturbance voltage of the secondary injection is v inj_p (i, t) the corresponding inverter responds to the output current i inv_p (i, t) ith (i.e. [1, N)]) The negative sequence disturbance voltage of the secondary injection is v inj_n (i, t) the corresponding inverter responding to the output currenti inv_n (i, t). For recorded positive sequence disturbance voltage v inj_p (i, t), negative sequence disturbance voltage v inj_n (i, t), inverter positive sequence response output current i inv_p (i, t), inverter negative sequence response output current i inv_n (i, t) performing Fourier analysis, extracting harmonic components, and applying positive sequence disturbance voltage v inj_p (i, t), negative sequence disturbance voltage v inj_n (i, t), inverter positive sequence response output current i inv_p (i, t), inverter negative sequence response output current i inv_n (i, t) converting from the time domain to the frequency domain to obtain a positive-sequence disturbance voltage v containing amplitude and phase information inj_p (i, s), negative sequence disturbance voltage v inj_n (i, s), inverter positive sequence response output current i inv_p (i, s), inverter negative sequence response output current i inv_n (i,s)。
Grid-connected system positive sequence integral impedance Z at corresponding frequency point sys_p (i,s)＝v inj_p (i,s)/i inv_p (i, s) grid-connected system negative sequence overall impedance Z sys_n (i,s)＝v inj_n (i,s)/i inv_n (i, s). And drawing positive sequence and negative sequence overall impedance of the grid-connected system according to analysis and calculation results at different frequency points.
Because of the frequency coupling effect, the impedance of the power grid can influence the impedance of the inverter, and the overall impedance of the grid-connected system also changes, in order to verify the effectiveness of the method for measuring the overall impedance of the grid-connected system, a simulation model is built in MATALB/Simulink for measurement verification. In the actual power grid, the power grid impedance mainly presents the inductance, and fig. 6 shows the comparison of the theoretical curve and the measurement result of the positive sequence overall impedance of the grid-connected system when the equivalent inductance of the power grid impedance is 1mH, 5mH and 8mH respectively. The triangle is the positive overall impedance of the grid-connected system measured when the equivalent inductance of the grid impedance is 1mH, the solid line is the theoretical curve of the positive overall impedance of the grid-connected system measured when the equivalent inductance of the grid impedance is 1mH, the circle is the theoretical curve of the positive overall impedance of the grid-connected system measured when the equivalent inductance of the grid impedance is 5mH, the dash line is the theoretical curve of the positive overall impedance of the grid-connected system measured when the equivalent inductance of the grid impedance is 5mH, the square is the theoretical curve of the positive overall impedance of the grid-connected system measured when the equivalent inductance of the grid impedance is 8mH, and the dotted line is the theoretical curve of the positive overall impedance of the grid-connected system measured when the impedance of the grid is 8 mH. FIG. 7 shows a comparison between a theoretical negative-sequence overall impedance curve and a measurement result of the grid-connected system when the equivalent impedance of the power grid is 1mH, 5mH and 8mH respectively. The triangle is the negative sequence integral impedance of the grid-connected system measured when the equivalent inductance of the power grid impedance is 1mH, the solid line is the theoretical curve of the negative sequence integral impedance of the grid-connected system measured when the equivalent inductance of the power grid impedance is 1mH, the circle is the negative sequence integral impedance of the grid-connected system measured when the equivalent inductance of the power grid is 5mH, the dash line is the theoretical curve of the negative sequence integral impedance of the grid-connected system measured when the equivalent inductance of the power grid is 5mH, the square is the negative sequence integral impedance of the grid-connected system measured when the equivalent inductance of the power grid is 8mH, and the dotted line is the theoretical curve of the negative sequence integral impedance of the grid-connected system measured when the equivalent inductance of the power grid is 8 mH. In conclusion, by comparing the measurement result with the theoretical curve, the method can accurately measure the integral impedance of the grid-connected system.
It should be noted that the above-mentioned embodiments are merely preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and equivalent substitutions or alternatives made on the basis of the above-mentioned technical solutions are all included in the scope of the present invention.
In the description of the present specification, the descriptions of the terms "one embodiment," "example," "specific example," and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims.
Claims (10)
1. The method and the device for measuring the overall impedance of the new energy grid-connected system are characterized by comprising the following steps:
s1, configuring a positive sequence disturbance signal aiming at a grid-connected system;
s2, applying voltage disturbance at a grid-connected point through a harmonic injection device;
s3, collecting disturbance voltage and network access current;
s4, configuring a negative sequence disturbance signal aiming at a grid-connected system;
s5, repeating the step S2 and the step S3;
s6, extracting harmonic components of the disturbance voltage and the network access current and performing time-frequency conversion;
s7, calculating the integral impedance of the grid-connected system according to the harmonic component.
2. The method for measuring the overall impedance of the grid-connected system according to claim 1, wherein the step S1 is to configure a positive sequence disturbance signal for the grid-connected system, and specifically comprises the following steps:
s11-determining the phase sequence of a three-phase positive sequence disturbance signal;
s12, configuring the amplitude of the disturbance signal according to the voltage level of the grid-connected point;
s13, determining a frequency band of impedance measurement;
s14, determining the number of impedance measurement frequency points and the frequency of each point to be measured.
3. The method for measuring the overall impedance of the grid-connected system according to claim 1, wherein the step S2 of applying the disturbance voltage to the grid-connected point through the harmonic injection device specifically comprises the following steps:
s21, generating a disturbance signal by using a frequency response analyzer;
s22, amplifying the disturbance signal into disturbance voltage by using a linear power amplifier and injecting the disturbance voltage into a grid-connected system.
4. The method for measuring the overall impedance of the grid-connected system according to claim 1, wherein the step S3 of collecting the disturbance voltage and the grid-in current specifically comprises the following steps:
s31, determining the sampling frequency of the sampling equipment according to the highest frequency to be detected;
s32-determining the continuous sampling time of the sampling equipment according to the lowest frequency to be detected;
s33, recording disturbance voltage and network access current by using sampling equipment.
5. The method for measuring the overall impedance of the grid-connected system according to claim 1, wherein the step S4 is to configure a negative sequence disturbance signal for the grid-connected system, and specifically comprises the following steps:
s41-determining the phase sequence of the three-phase negative sequence disturbance signal;
s42, configuring the amplitude of the disturbance signal according to the voltage level of the grid-connected point;
s43, determining a frequency band of impedance measurement;
s44, determining the number of impedance measurement frequency points and the frequency of each point to be measured.
6. The method for measuring the overall impedance of the grid-connected system according to claim 1, wherein the step S6 is to extract harmonic components of the disturbance voltage and the grid-connected current and perform time-frequency conversion, and specifically comprises the following steps: using Fourier transforms to correct sequence perturbation voltages v inj_p (t), positive sequence inverter response output current i inv_p (t), negative sequence disturbance voltage v inj_n (t), negative sequence inverter responsive to output current i inv_p (t) performing harmonic extraction, and converting harmonic components from a time domain to a frequency domain to obtain complex frequency domain harmonic components: positive sequence disturbance voltage V inj_p (s), positive sequence inverter response output current I inv_p (s) negative sequence disturbance Voltage V inj_n (s), negative sequence inverter responsive to output current I inv_n (s)。
7. The method for measuring the overall impedance of the grid-connected system according to claim 1, wherein the step S7 is to calculate the overall impedance of the grid-connected system according to harmonic components, specifically as follows: calculating the overall impedance of the grid-connected systemZ sys (s):
8. A grid-tie system overall impedance measurement apparatus, comprising:
a first configuration module: configuring a positive sequence disturbance signal aiming at a grid-connected system;
and (3) an application module: applying voltage disturbance at a grid-connected point through a harmonic injection device;
and the acquisition module is used for: collecting disturbance voltage and network access current;
and a second configuration module: configuring a negative sequence disturbance signal aiming at a grid-connected system;
and (3) repeating the module: repeating the step S2 and the step S3;
and an extraction module: extracting harmonic components of disturbance voltage and network access current and performing time-frequency conversion;
the calculation module: and calculating the integral impedance of the grid-connected system according to the harmonic components.
9. The grid-tie system overall impedance measurement apparatus of claim 8, wherein the first configuration module comprises the steps of:
determining the phase sequence of a three-phase positive sequence disturbance signal;
configuring the amplitude of the disturbance signal according to the voltage level of the grid-connected point;
determining a frequency band of impedance measurement;
determining the number of impedance measurement frequency points and the frequency of each point to be measured;
the application module comprises the following steps:
generating a disturbance signal by using a frequency response analyzer;
amplifying the disturbance signal into disturbance voltage by using a linear power amplifier and injecting the disturbance voltage into a grid-connected system;
the acquisition module comprises the following steps:
determining the sampling frequency of the sampling equipment according to the highest frequency to be detected;
determining the continuous sampling time of the sampling equipment according to the lowest frequency to be detected;
and recording disturbance voltage and network access current by using sampling equipment.
10. The grid-tie system overall impedance measurement apparatus of claim 8, wherein the second configuration module comprises the steps of:
determining the phase sequence of a three-phase negative sequence disturbance signal;
configuring the amplitude of the disturbance signal according to the voltage level of the grid-connected point;
determining a frequency band of impedance measurement;
determining the number of impedance measurement frequency points and the frequency of each point to be measured;
the extraction module comprises the following steps: using Fourier transforms to correct sequence perturbation voltages v inj_p (t), positive sequence inverter response output current i inv_p (t), negative sequence disturbance voltage v inj_n (t), negative sequence inverter responsive to output current i inv_p (t) performing harmonic extraction, and converting harmonic components from a time domain to a frequency domain to obtain complex frequency domain harmonic components: positive sequence disturbance voltage V inj_p (s), positive sequence inverter response output current I inv_p (s) negative sequence disturbance Voltage V inj_n (s), negative sequence inverter responsive to output current I inv_n (s)；
The computing module includes: calculating the integral impedance Z of the grid-connected system sys (s):
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310173496.1A CN116087623A (en) | 2023-02-28 | 2023-02-28 | Method and device for measuring overall impedance of new energy grid-connected system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310173496.1A CN116087623A (en) | 2023-02-28 | 2023-02-28 | Method and device for measuring overall impedance of new energy grid-connected system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116087623A true CN116087623A (en) | 2023-05-09 |
Family
ID=86200895
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310173496.1A Pending CN116087623A (en) | 2023-02-28 | 2023-02-28 | Method and device for measuring overall impedance of new energy grid-connected system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116087623A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116735971A (en) * | 2023-05-12 | 2023-09-12 | 武汉大学 | Multi-node impedance measurement device and method for power distribution network |
-
2023
- 2023-02-28 CN CN202310173496.1A patent/CN116087623A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116735971A (en) * | 2023-05-12 | 2023-09-12 | 武汉大学 | Multi-node impedance measurement device and method for power distribution network |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112103982B (en) | MMC small-signal impedance modeling method based on Fourier decomposition | |
| Buticchi et al. | A DC offset current compensation strategy in transformerless grid-connected power converters | |
| CN101615854B (en) | Control method of three-phase voltage type PWM rectifier under unbalance voltage of power grid | |
| CN104052323B (en) | Neutral-point voltage balance system and method based on power-factor angle | |
| CN106505840A (en) | A kind of grid-connected photovoltaic inverter harmonic wave management method | |
| CN103904922A (en) | Control method based on virtual flux linkage orientation and used for voltage-type rectifier | |
| CN106950512B (en) | Energy storage converter grid-connected and grid-disconnected characteristic integrated detection system and method | |
| CN110198130A (en) | More vector optimization control systems and method under the conditions of a kind of unbalanced power grid | |
| Shen et al. | Current control optimization for grid-tied inverters with grid impedance estimation | |
| CN103166489A (en) | Control circuit for three-phase high power factor rectifier | |
| CN116087623A (en) | Method and device for measuring overall impedance of new energy grid-connected system | |
| CN111505439A (en) | Impedance frequency sweeping device for direct current system, control method thereof and storage medium | |
| CN111682542A (en) | Harmonic coupling external characteristic prediction method of three-phase rectification circuit | |
| CN102290587B (en) | Redox flow cell simulation method and simulator | |
| CN114142751B (en) | Three-phase CSR proportional integral resonance control method under unbalanced power grid voltage | |
| CN109120013B (en) | Method and device for detecting injection disturbance quantity of power grid adaptability detection device | |
| Lin et al. | NOC-based multiple low-order harmonic currents suppression method | |
| CN113839387A (en) | LCL type active power filter system and method of passive interface | |
| CN114172394A (en) | Control system and control method of energy-feedback type alternating current electronic load | |
| CN107482616B (en) | Distributed power supply high-frequency impedance equivalent modeling method | |
| CN107565564A (en) | Active Power Filter-APF and its quick composite control method based on quick Repetitive controller | |
| CN110011524B (en) | Control method, device and equipment for harmonic suppression and readable storage medium | |
| CN106385030B (en) | A kind of harmonic voltage control method of Active Power Filter-APF | |
| CN110829489B (en) | Estimation method for disturbance-free signal injection weak power grid and series compensation power grid | |
| CN108899906B (en) | Built-in repetitive dead beat control method for three-phase four-wire APF |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |