CN111209527B - Generalized impedance measuring method for non-variable working condition inverter with secondary side applying disturbance - Google Patents

Generalized impedance measuring method for non-variable working condition inverter with secondary side applying disturbance Download PDF

Info

Publication number
CN111209527B
CN111209527B CN201911418200.8A CN201911418200A CN111209527B CN 111209527 B CN111209527 B CN 111209527B CN 201911418200 A CN201911418200 A CN 201911418200A CN 111209527 B CN111209527 B CN 111209527B
Authority
CN
China
Prior art keywords
disturbance
inverter
current
sampling
impedance
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.)
Active
Application number
CN201911418200.8A
Other languages
Chinese (zh)
Other versions
CN111209527A (en
Inventor
辛焕海
万炜
汪震
鞠平
蒙志全
杨超然
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zhejiang University ZJU
State Grid Corp of China SGCC
State Grid Zhejiang Electric Power Co Ltd
Original Assignee
Zhejiang University ZJU
State Grid Corp of China SGCC
State Grid Zhejiang Electric Power Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Zhejiang University ZJU, State Grid Corp of China SGCC, State Grid Zhejiang Electric Power Co Ltd filed Critical Zhejiang University ZJU
Priority to CN201911418200.8A priority Critical patent/CN111209527B/en
Publication of CN111209527A publication Critical patent/CN111209527A/en
Application granted granted Critical
Publication of CN111209527B publication Critical patent/CN111209527B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
    • G06F17/141—Discrete Fourier transforms
    • 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

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Computational Mathematics (AREA)
  • Mathematical Analysis (AREA)
  • Mathematical Optimization (AREA)
  • Pure & Applied Mathematics (AREA)
  • Data Mining & Analysis (AREA)
  • Theoretical Computer Science (AREA)
  • Discrete Mathematics (AREA)
  • Algebra (AREA)
  • Databases & Information Systems (AREA)
  • Software Systems (AREA)
  • General Engineering & Computer Science (AREA)
  • Measurement Of Resistance Or Impedance (AREA)

Abstract

The invention discloses a generalized impedance measuring method of a non-variable working condition inverter with secondary side applying disturbance. Applying disturbance to a current reference value of an inner control ring by an inverter inner ring current control input end of the inverter grid-connected system controlled by the double-ring vector; sampling three-phase voltage and current output by the inverter before and after disturbance application by using sampling equipment; calculating the disturbance quantity, and transforming the disturbance quantity from a time domain to a frequency domain by using discrete Fourier transform; calculating different applied disturbances to obtain generalized impedance; and changing the frequency of the applied disturbance to sweep frequency until the generalized impedance of all frequency points in the frequency band to be measured is measured. The invention measures the generalized impedance of the inverter, has more convenient measurement and lower cost, does not change the working condition, and also reduces the interference of field factors generated by multiple measurements.

Description

Generalized impedance measuring method for non-variable working condition inverter with secondary side applying disturbance
Technical Field
The invention relates to a method for measuring inverter parameters, in particular to a method for measuring generalized impedance of an inverter under any power factor under the same working condition based on secondary side applied disturbance.
Background
With the aggravation of global energy crisis and the aggravation of environmental pollution problems, renewable clean energy represented by wind power and photovoltaic is increasingly valued by the energy industry. On one hand, the new energy power generation generally has strong randomness, intermittency and fluctuation, belongs to a power supply with strong random fluctuation and low controllability, and the problem of the overall safety of a power grid can be caused when the power grid is accessed in a large scale. On the other hand, the access of large-scale power electronic equipment changes the dynamic characteristics of a power grid, so that the power electronic characteristics of a power system become more and more obvious. In recent years, many oscillation problems related to new energy units have occurred around the world, and new challenges are brought to the safe and stable operation of power systems.
The stability of the grid-connected system can be judged by establishing an impedance model and analyzing the impedance of the inverter and the network, and guidance is given to the design of inverter control. The generalized impedance of the three-phase grid-connected system is strictly derived mathematically to obtain an inverter generalized admittance matrix in a diagonal form and a network generalized admittance matrix in a symmetrical form (the generalized impedance is the inverse of the generalized admittance), so that the grid-connected stability of the inverter can be conveniently analyzed.
The generalized impedance model can be obtained by an analytical method or a method of externally adding a measuring device. The existing impedance measurement method injects disturbance by a method of externally adding high-voltage equipment, and the equipment is expensive and the operation is more complicated. The disturbance is injected by the inverter and the device of the power grid for measurement, and particularly, the disturbance is added on the secondary side, namely a control part, so that the equipment is more convenient and the cost is lower.
The existing generalized impedance measurement technology for secondary side injection disturbance mostly needs variable working condition measurement under the premise that the power factor is 1, the power factor is not 1, the experiment times are more, the variable working condition is more complex, and thus, the method is not only inconvenient, and more uncertain errors are introduced by multiple measurements.
Disclosure of Invention
In order to solve the problems in the background art, the invention discloses a generalized impedance measuring method of a non-variable working condition inverter with disturbance applied to a secondary side, which is a generalized impedance measuring method of a converter under any power factor of a non-variable working condition of secondary system injection disturbance. The method can be used for measuring the generalized impedance of the inverter when the inverter is connected to the grid under the condition that the power factor is 1 under the same working condition, and third-party software is adopted in a computer for off-line processing.
The secondary side is the low-voltage side of the inverter grid-connected system, and the disturbance applied to the secondary side is applied to a control loop of the inverter. The non-variable condition refers to the measurement under the same condition.
As shown in fig. 1, the technical scheme of the invention adopts the following steps:
1) aiming at a double-loop vector control inverter grid-connected system, an inverter is connected to a power grid to form the inverter grid-connected system, the power factor of the inverter grid-connected system is not 1, and disturbance is applied to a current reference value of an inner control loop at the current control input end of the inner loop of the inverter;
2) sampling three-phase voltage and current output by the inverter before and after disturbance application by using sampling equipment to obtain sampling values, and obtaining components of the voltage and the current in a dq coordinate system after coordinate transformation of the obtained sampling values;
3) calculating the disturbance quantity, and transforming the disturbance quantity from a time domain to a frequency domain by using discrete Fourier transform;
4) repeating the steps 1) to 3) and applying different disturbances in the step 1), carrying out measurement twice in total, and calculating to obtain generalized impedance by using the applied disturbances, the calculated disturbance quantity and the transmission parameter of the phase-locked loop according to the generalized impedance port characteristic of the inverter;
5) and (3) repeating the steps 1) to 4) and changing the frequency of the disturbance applied in the step 1) to sweep frequency until the generalized impedance of all frequency points in the frequency band to be measured is measured.
In the step 1), the grid-connected inverter adopts double-loop vector control, and the inner loop is a vectorCurrent control, power control on the outer ring, and d-axis component I of current ring vector control reference value on the inner ring current control input end of the inverter for applying disturbancedrefQ-axis component I of the sum current loop vector control reference valueqrefA sinusoidal perturbation is applied.
The step 4) is specifically as follows:
in the conventional method, when the power factor is 1, the generalized impedance port characteristic of the inverter when the current reference value is disturbed is expressed by the following formula:
Figure BDA0002351712820000021
in the present invention, however, different generalized impedance port characteristics of the inverter are established.
4.1) establishing the following generalized impedance port characteristics of the inverter when a perturbation is applied to the current reference:
Figure BDA0002351712820000022
wherein, Delta U ', Delta I'),
Figure BDA0002351712820000023
Delta' represents the voltage amplitude U, the current amplitude I and the current phase angle of the sampling value under the global rotating polar coordinate
Figure BDA0002351712820000024
And the result of the discrete Fourier transform of the disturbance variable of the voltage phase angle delta, i.e. the result of step 3), delta l'dperAnd Δ I'qperDiscrete Fourier transform results, Y, of d-axis and q-axis components respectively representing applied disturbances on current reference values of the inner control loopg1(s)、Yg2(s)、Yg3(s)、Yg4(s) respectively represent a first, a second, a third and a fourth transfer parameter, Yg5(s)、Yg6(s)、Yg7(s)、Yg8(s) represents the disturbance from the current reference value to the three-phase current amplitude disturbanceThe fifth, sixth, seventh and eighth transfer parameters of the momentum delta I;
wherein the content of the first and second substances,
Figure BDA0002351712820000031
a generalized impedance matrix.
The global rotation polar coordinate system is a coordinate system which takes an infinite power grid as a reference system and takes voltage in the power grid as a polar axis. The angle theta of the global rotating polar coordinate system relative to the static coordinate system adopts a given mode, adopts a waveform which changes along with time as a sawtooth wave, and the slope is (2 pi x 50) rad/s, namely, the synchronous rotating speed omega is adopted0(100 π rad/s) increases with a period of 0.02s and an amplitude of 2 π. The static coordinate system refers to an abc three-phase coordinate system
4.2) repeating the steps 1) to 3), applying disturbance with the same frequency and different amplitudes in the step 1), and carrying out measurement twice to obtain a disturbance quantity delta D of each electrical parameter and a frequency domain result of discrete Fourier transform, wherein each electrical parameter comprises three-phase voltage and three-phase current output by the inverter;
4.3) then solving is carried out on the dq coordinate system by using the result obtained in the step 4.2), and then the solution is converted into a global polar coordinate system to obtain generalized impedance:
4.3.1) obtaining the discrete Fourier transform result of the electrical parameter disturbance quantity delta D under the frequency domain by using two times of measurement, substituting the discrete Fourier transform result into the following formula to calculate and obtain the transfer parameter under the dq axis in the generalized impedance matrix:
Figure BDA0002351712820000032
wherein subscripts 1 and 2 denote the two sets of results, Δ l ', measured after two perturbations were applied'dper1And Δ I'dper2Represents the discrete Fourier transform results, Δ l ', of the d-axis component of the applied disturbance at the current reference values of the inner control loop after the first and second applied disturbances, respectively'qper1And Δ I'qper2Discrete Fourier components representing q-axis components of applied perturbations on current references of the inner control loop after a first application of perturbation and after a second application of perturbation, respectivelyLeaf transform result, Δ U'd1And delta U'd2The results of discrete Fourier transform of the disturbance amounts of the d-axis components of the voltages after the first disturbance application and the second disturbance application, respectively, are shown as Δ U'q1And delta U'q2Represents the discrete Fourier transform results, Delta I ', of the disturbance quantities of the q-axis components of the voltages after the first and second measurements, respectively'd1And Δ I'd2Representing the results of discrete Fourier transforms, DI ', of the perturbation quantities of the d-axis components of the currents after the first and after the second measurements, respectively'q1And Δ I'q2Discrete Fourier transform results respectively representing disturbance quantities of q-axis components of the current after the first measurement and after the second measurement; y isdd、Ydq、Yqq、YperRespectively a first impedance port characteristic parameter, a second impedance port characteristic parameter, a third impedance port characteristic parameter and a fourth impedance port characteristic parameter under a dq coordinate system;
first, second, third and fourth impedance port characteristic parameters Ydd、Ydq、Yqq、YperThe characteristic parameters of the impedance port under the dq coordinate system are as follows:
Figure BDA0002351712820000033
then the first, the second and the third impedance port characteristic parameters Y are measureddd、Ydq、YqqSubstituting the following formula to calculate and obtain a first transfer parameter Y, a second transfer parameter Y, a third transfer parameter Y and a fourth transfer parameter Yg1(s)、Yg2(s)、Yg3(s)、Yg4(s)：
Figure BDA0002351712820000041
Wherein Hpll(s) is a transfer parameter of the phase locked loop, IdAnd IqRespectively representing the d-and q-axis components, U, of the steady-state current output by the converter under non-varying conditionsdRepresents the d-axis component of the steady-state voltage under the working condition, delta is the voltage phase angle under the global rotating polar coordinate,
Figure BDA0002351712820000042
is a current phase angle under a global rotating polar coordinate;
4.3.2) finally forming a generalized impedance matrix from the eight obtained transfer parameters.
The prior art solves the problem of measuring the power factor which is not 1, and adopts a processing method of variable working condition measurement. The invention makes the system operate under no-load and normal two working conditions by non-variable working condition, carries out four times of disturbance injection, and then solves Yg1(s)、Yg2(s)、Yg3(s)、Yg4(s)、Yg5(s)、Yg6(s)、Yg7(s)、Yg8(s), the invention carries out measurement under the same working condition, and only 2 times of disturbance injection is needed for measurement.
In the step 4.2), the disturbance quantity Δ D is calculated by using the following formula:
ΔD(kΔt)＝D(kΔt)-D(kΔt-T)
wherein D represents an electrical parameter, Δ D represents the disturbance quantity of each electrical parameter, k Δ T represents the sampling period in a disturbance state, k Δ T-T represents the sampling period in an undisturbed state, T represents the time difference of the starting point of sampling before and after disturbance application, k represents the ordinal number of each sampling in the sampling before and after disturbance application, and Δ T represents the sampling interval.
In the step 2), the sampling device is a six-circuit AD sampling device with a synchronous sampling function, and the sampling value comprises a three-phase voltage Ua、Ub、UcAnd three-phase current Ia、Ib、IcFor a total of six electrical parameters.
And in the step 2), AD sampling is carried out after the transient process of the system is finished, sampling is carried out when the system runs at a stable working point before disturbance application, and sampling is carried out after the system stably runs at sinusoidal disturbance after disturbance application.
In the step 2), the coordinate transformation is processed by adopting the following formula to obtain the voltage and current values under the dq coordinate system:
Figure BDA0002351712820000043
Figure BDA0002351712820000044
wherein, Ua、Ub、UcRepresenting three-phase voltages, I, in a sampled stationary coordinate systema、Ib、IcRepresenting the three-phase current in the sampled stationary coordinate system, theta representing the angle of the global rotating coordinate system with respect to the stationary coordinate system, Ud、UqRespectively representing d-axis and q-axis voltage values in a global rotation rectangular coordinate system, Id、IqRespectively representing d-axis and q-axis current values under a global rotation rectangular coordinate system;
and then the amplitude and the phase angle of the voltage and the current under the global rotating polar coordinate system are calculated and obtained by adopting the following formulas:
Figure BDA0002351712820000051
Figure BDA0002351712820000052
Figure BDA0002351712820000053
Figure BDA0002351712820000054
wherein U represents a voltage amplitude in a global rotation polar coordinate, I represents a current amplitude in the global rotation polar coordinate,
Figure BDA0002351712820000055
represents the current phase angle under the global rotation polar coordinate, delta is the voltage phase angle under the global rotation polar coordinate, Ux、UyRespectively representing all in steady stateD-axis component and q-axis component of voltage in local rectangular coordinate system, Ix、IyRespectively representing the d-axis component and the q-axis component of the current in a global rectangular coordinate system in a steady state.
The global rectangular coordinate system is a coordinate system which takes an infinite power grid as a reference system and takes voltage in the power grid as an x-axis.
The invention obtains the generalized admittance characteristics of the inverter port through an actual measurement method, and the generalized admittance characteristics are used as a judgment basis of the stability of the grid-connected inverter or provide reference for the design of a controller, thereby providing early warning and guidance for oscillation risks possibly existing during new energy grid connection, and also providing new technical standards for the design of new energy.
The invention has the beneficial effects that:
according to the invention, the generalized impedance of the inverter is measured by using the original equipment of the inverter grid-connected system, high-voltage equipment is not required to be added for controlling system injection disturbance, the operation is more convenient and faster, and the cost is lower; the sampled signals are converted into a dq coordinate system for calculation and then converted into a global coordinate system, and the number of parameters to be measured is reduced in the method.
Compared with the conventional measuring method for the injection disturbance of the control system, the method can measure the condition that the power factor is not 1, does not need to change working conditions, is more convenient and accurate, saves cost, reduces the interference of field factors generated by multiple measurements, and can be used for the stability analysis of a grid-connected system and the control design of an inverter.
Therefore, the method of applying disturbance on the secondary side is adopted, the existing controller equipment is utilized, the disturbance is applied to the control ring, the disturbance injection equipment does not need to be connected to the high-voltage end, the grid disconnection of the inverter is not needed, the measurement can be carried out when the inverter is connected to the grid, and the accurate measurement can be realized.
Drawings
Fig. 1 is a schematic diagram of generalized impedance measurement process steps.
Fig. 2 is a schematic diagram of an inverter grid-connected system.
Fig. 3 is a waveform of the global transformation angle θ as a function of time.
FIG. 4 is a schematic view of a current-voltage vector of a global rotating coordinate system.
Fig. 5 is a schematic diagram of two-injection perturbation.
FIG. 6 is a comparison of the magnitude of various parameters of theoretical and measured values of generalized impedance.
FIG. 7 is a phase angle comparison of various parameters for theoretical and measured values of generalized impedance.
Detailed Description
The invention is described in further detail below with reference to the drawings and the specific embodiments.
The embodiment and the implementation process of the complete method according to the invention content are as follows:
as shown in fig. 2, the grid-connected inverter system according to the embodiment of the present invention has an inverter output connected to an LCL filter, and the grid-connected inverter uses dual-loop vector control, in which an inner loop is vector current control and an outer loop is PQ control. A simulation model shown in figure 2 is established in MATLAB/Simulink, the direct-current voltage of an inverter is constant, LC filtering is adopted for output, and reference values of active current and reactive current of the inverter are IdrefAnd IqrefThe parameters used by the inverter are shown in table 1.
TABLE 1
Description of the invention Numerical value
Base value of system power 2000VA
Base value of system voltage 575V
LC filter inductor 0.05pu
LC filter capacitor 0.05pu
Inner loop PI proportional gain 0.3
Inner loop PI integral gain 10
Phase-locked loop PI proportional gain 60
Phase-locked loop PI integral gain 1400
Power outer loop PI proportional gain 1
Power outer loop PI integral gain 5
Inverter control frequency 10kHz
Sampling rate of measuring device 0.2MHz
Disturbance injected by inner ring is inner ring current reference value IdrefAnd IqrefSuperimposing a sinusoidal signal, as shown in fig. 2, a sinusoidal disturbance signal Δ I is superimposed to the control moduledperAnd Δ IqperThree-phase voltage U output to inverter by using sampling modulea、Ub、UcAnd three-phase current Ia、Ib、IcAnd (5) sampling and recording.
SamplingThe object is shown in FIG. 2 and comprises three-phase voltage Ua、Ub、UcAnd three-phase current Ia、Ib、IcThe three-phase voltage is the voltage of an output point of the inverter filter, the three-phase current is the current on an output filter inductor of the inverter, and the AD sampling equipment is 6 paths of AD sampling equipment with a synchronous sampling function.
When applying a disturbance, the waveform of the angle θ of the global rotating coordinate system relative to the stationary coordinate system as a function of time is shown in FIG. 3 at a synchronous rotational speed ω0(100. pi. rad/s) increased.
The current and voltage vectors in the global rotation coordinate are shown in fig. 4, the current and voltage vectors can be expressed in rectangular coordinates and polar coordinates, and the global rotation rectangular coordinate is transformed to the global rotation polar coordinate by coordinate transformation according to a formula.
In the embodiment, two times of disturbance injection are performed on generalized impedance of the same frequency, as shown in fig. 5, multiple dq-axis reference value disturbance injected at one frequency point have the same frequency and different amplitude values relatively, and vectors formed on a dq coordinate system are linearly independent.
Therefore, by using the generalized impedance measurement and calculation method of the invention, the transmission parameters of the generalized impedance port characteristics within 0-100Hz are calculated, the amplitude-frequency characteristics and the phase-frequency characteristics are drawn, and the results are shown in fig. 6 and 7 by comparing with the transmission parameters obtained by theoretical calculation.
As can be seen from fig. 6 and 7, the amplitude-frequency characteristic of the generalized impedance transfer parameter measured by the generalized impedance measurement method of the present invention substantially matches the phase-frequency characteristic and the theoretically calculated generalized impedance. This shows that the generalized impedance port characteristic of the inverter can be calculated accurately by using the invention.
According to the simulation example, the generalized impedance method based on the secondary side disturbance can accurately measure the characteristics of the inverter of the grid-connected system and the generalized impedance port of the grid side. According to the measuring method provided by the invention, high-voltage equipment is not required to be added for controlling system injection disturbance, the operation is more convenient and faster, and the cost is lower; compared with the traditional measuring method for the injection disturbance of the control system, the method does not need to change working conditions, is more convenient and accurate, and saves cost.
The foregoing detailed description is intended to illustrate and not limit the invention, which is intended to be within the spirit and scope of the appended claims, and any changes and modifications that fall within the true spirit and scope of the invention are intended to be covered by the following claims.

Claims (4)

1. A generalized impedance measuring method of a non-variable working condition inverter with disturbance applied to the secondary side is characterized by comprising the following three steps:
1) for a double-loop vector control inverter grid-connected system, applying disturbance to a current reference value of an inner control loop at an inner loop current control input end of an inverter;
2) sampling three-phase voltage and current output by the inverter before and after disturbance application by using sampling equipment to obtain sampling values, and obtaining components of the voltage and the current in a dq coordinate system after coordinate transformation of the obtained sampling values;
3) calculating the disturbance quantity, and transforming the disturbance quantity from a time domain to a frequency domain by using discrete Fourier transform;
4) repeating the steps 1) to 3) and applying different disturbances in the step 1), carrying out measurement twice in total, and calculating to obtain generalized impedance by using the applied disturbances, the calculated disturbance quantity and the transmission parameter of the phase-locked loop according to the generalized impedance port characteristic of the inverter;
5) repeating the steps 1) to 4) and changing the frequency of the disturbance applied in the step 1) to sweep frequency until the generalized impedance of all frequency points in the frequency band to be measured is measured;
the method is characterized in that: the step 4) is specifically as follows:
4.1) establishing the following generalized impedance port characteristics of the inverter when a perturbation is applied to the current reference:
Figure FDA0003194031840000011
wherein, Delta U ', Delta I'),
Figure FDA0003194031840000012
Delta' represents the voltage amplitude U, the current amplitude I and the current phase angle of the sampling value under the global rotating polar coordinate
Figure FDA0003194031840000013
And the result of a discrete Fourier transform of the disturbance variable of the voltage phase angle delta, Delta l'dperAnd Δ I'qperDiscrete Fourier transform results, Y, of d-axis and q-axis components respectively representing applied disturbances on current reference values of the inner control loopg1(s)、Yg2(s)、Yg3(s)、Yg4(s) respectively represent a first, a second, a third and a fourth transfer parameter, Yg5(s)、Yg6(s)、Yg7(s)、Yg8(s) fifth, sixth, seventh, eighth transfer parameters;
4.2) repeating the steps 1) to 3), applying disturbance with the same frequency and different amplitudes in the step 1), and carrying out measurement twice to obtain a disturbance quantity delta D of each electrical parameter and a frequency domain result of discrete Fourier transform, wherein each electrical parameter comprises three-phase voltage and three-phase current output by the inverter;
4.3) then solving is carried out on the dq coordinate system by using the result obtained in the step 4.2), and then the solution is converted into a global polar coordinate system to obtain generalized impedance:
4.3.1) obtaining the discrete Fourier transform result of the electrical parameter disturbance quantity delta D under the frequency domain by using two times of measurement, substituting the discrete Fourier transform result into the following formula to calculate and obtain the transfer parameter under the dq axis in the generalized impedance matrix:
Figure FDA0003194031840000021
wherein subscripts 1 and 2 denote the two sets of results, Δ l ', measured after two perturbations were applied'dper1And Δ I'dper2Represents the discrete Fourier transform results, Δ l ', of the d-axis component of the applied disturbance at the current reference values of the inner control loop after the first and second applied disturbances, respectively'qper1And ΔI′qper2Represents the discrete Fourier transform results, Δ U ', of the q-axis component of the applied disturbance on the current reference values of the inner control loop after the first application of disturbance and after the second application of disturbance, respectively'd1And delta U'd2The results of discrete Fourier transform of the disturbance amounts of the d-axis components of the voltages after the first disturbance application and the second disturbance application, respectively, are shown as Δ U'q1And delta U'q2Represents the discrete Fourier transform results, Delta I ', of the disturbance quantities of the q-axis components of the voltages after the first and second measurements, respectively'd1And Δ I'd2Represents the discrete Fourier transform results, Delta I ', of the disturbance quantities of the d-axis components of the currents after the first and second measurements, respectively'q1And Δ I'q2Discrete Fourier transform results respectively representing disturbance quantities of q-axis components of the current after the first measurement and after the second measurement; y isdd、Ydq、Yqq、YperRespectively a first impedance port characteristic parameter, a second impedance port characteristic parameter, a third impedance port characteristic parameter and a fourth impedance port characteristic parameter under a dq coordinate system;
first, second, third and fourth impedance port characteristic parameters Ydd、Ydq、Yqq、YperThe characteristic parameters of the impedance port under the dq coordinate system are as follows:
Figure FDA0003194031840000022
then the first, the second and the third impedance port characteristic parameters Y are measureddd、Ydq、YqqSubstituting the following formula to calculate and obtain a first transfer parameter Y, a second transfer parameter Y, a third transfer parameter Y and a fourth transfer parameter Yg1(s)、Yg2(s)、Yg3(s)、Yg4(s)：
Figure FDA0003194031840000023
Wherein Hpll(s) is a transfer parameter of the phase locked loop, IdAnd IqRespectively representing non-varying operating conditionsD-and q-axis components, U, of the steady-state current output by the time-varying converterdThe d-axis component representing the steady state voltage at this condition,
Figure FDA0003194031840000024
is a current phase angle under a global rotating polar coordinate;
4.3.2) finally forming a generalized impedance matrix from the eight obtained transfer parameters.
2. The method for measuring the generalized impedance of the non-variable condition inverter with the secondary side applying disturbance according to claim 1, is characterized in that: in the step 1), the grid-connected inverter adopts double-loop vector control, the inner loop is vector current control, the outer loop is power control, and the disturbance is applied by a d-axis component I of a current loop vector control reference value at the current control input end of the inner loop of the inverterdrefQ-axis component I of the sum current loop vector control reference valueqrefA sinusoidal perturbation is applied.
3. The method for measuring the generalized impedance of the non-variable condition inverter with the secondary side applying disturbance according to claim 1, is characterized in that: in the step 4.2), the disturbance quantity Δ D is calculated by using the following formula:
ΔD(kΔt)＝D(kΔt)-D(kΔt-T)
wherein D represents an electrical parameter, Δ D represents the disturbance quantity of each electrical parameter, k Δ T represents the sampling period in a disturbance state, k Δ T-T represents the sampling period in an undisturbed state, T represents the time difference of the starting point of sampling before and after disturbance application, k represents the ordinal number of each sampling in the sampling before and after disturbance application, and Δ T represents the sampling interval.
4. The method for measuring the generalized impedance of the non-variable condition inverter with the secondary side applying disturbance according to claim 1, is characterized in that:
in the step 2), the sampling device is a six-circuit AD sampling device with a synchronous sampling function, and the sampling value comprises a three-phase voltage Ua、Ub、UcAnd three-phase current Ia、Ib、IcFor a total of six electrical parameters.
CN201911418200.8A 2019-12-31 2019-12-31 Generalized impedance measuring method for non-variable working condition inverter with secondary side applying disturbance Active CN111209527B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201911418200.8A CN111209527B (en) 2019-12-31 2019-12-31 Generalized impedance measuring method for non-variable working condition inverter with secondary side applying disturbance

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201911418200.8A CN111209527B (en) 2019-12-31 2019-12-31 Generalized impedance measuring method for non-variable working condition inverter with secondary side applying disturbance

Publications (2)

Publication Number Publication Date
CN111209527A CN111209527A (en) 2020-05-29
CN111209527B true CN111209527B (en) 2021-09-28

Family

ID=70789893

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201911418200.8A Active CN111209527B (en) 2019-12-31 2019-12-31 Generalized impedance measuring method for non-variable working condition inverter with secondary side applying disturbance

Country Status (1)

Country Link
CN (1) CN111209527B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112649670B (en) * 2020-11-20 2022-03-22 武汉大学 Grid-connected converter system impedance measurement method under unfavorable power grid condition and related equipment
CN114325097A (en) * 2021-11-18 2022-04-12 浙江大学 Doubly-fed power generation equipment impedance measurement method based on secondary side disturbance injection

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106526328A (en) * 2016-12-08 2017-03-22 浙江大学 Generalized impedance measurement and calculation method applicable to power grid and networking equipment
CN107608933A (en) * 2017-08-11 2018-01-19 浙江大学 A kind of inverter generalized impedance measuring method for applying disturbance based on secondary side

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9562939B2 (en) * 2012-07-30 2017-02-07 Huntington Ingalls Incorporated System and method for impedance measurement using series and shunt injection
CN109787280B (en) * 2019-01-17 2020-07-07 合肥工业大学 Inverter system line impedance simulation method based on initial impedance angle

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106526328A (en) * 2016-12-08 2017-03-22 浙江大学 Generalized impedance measurement and calculation method applicable to power grid and networking equipment
CN107608933A (en) * 2017-08-11 2018-01-19 浙江大学 A kind of inverter generalized impedance measuring method for applying disturbance based on secondary side

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Equivalent Power System Impedance Estimation Using Voltage and Current Measurements;Brandon L. Eidson et al.;《2014 Clemson University Power Systems Conference》;20140311;第1-6页 *
带阻抗观测器的单相逆变器抗扰控制;闫士杰 等;《电机与控制学报》;20140731;第18卷(第7期);第44-50页，第59页 *

Also Published As

Publication number Publication date
CN111209527A (en) 2020-05-29

Similar Documents

Publication Publication Date Title
CN107608933B (en) Inverter generalized impedance measurement method based on secondary side disturbance
CN108616141A (en) The control method of LCL gird-connected inverters power nonlinear in micro-capacitance sensor
CN111239491B (en) Generalized impedance real-time experimental measurement method adopting physical controller disturbance injection
CN107121609A (en) A kind of electric network impedance on-line identification method and device that injection is disturbed based on PRBS
CN108280271B (en) Unified power flow controller equivalent modeling method based on switching period average principle
CN106936125B (en) Generalized second-order integral phase-locked loop small signal impedance modeling method
CN107611991B (en) Parameter design method of LC coupling type SVG under unbalanced power grid and control method and system thereof
CN111209527B (en) Generalized impedance measuring method for non-variable working condition inverter with secondary side applying disturbance
CN109586337B (en) Frequency domain modeling-based VSC grid-connected system subsynchronous oscillation risk assessment method
CN114325097A (en) Doubly-fed power generation equipment impedance measurement method based on secondary side disturbance injection
CN111157798A (en) Impedance measurement system based on real-time simulator and object controller
Kong et al. Phase-locked strategy of photovoltaic connected to distribution network with high proportion electric arc furnace
CN207472983U (en) A kind of electric network impedance on-line identification device based on PRBS disturbance injections
CN110266036B (en) Dimension reduction method for multi-dimensional frequency domain impedance of current transformer
CN111308207A (en) Dq impedance measuring method for single-phase alternating current system
CN111525567B (en) Method and device for calculating fault current of photovoltaic grid-connected inverter
CN114509628A (en) Method and system for detecting grid-connected performance of high-capacity new energy and energy storage unit
CN108680792B (en) Dynamic admittance measuring method for new energy grid-connected system with power electronic device
CN107017643A (en) A kind of static reacance generator of dead-beat current control
CN112994113A (en) Doubly-fed wind generator sequence impedance modeling method and system
Zhang et al. Detection of Harmonic Components using the FFT and Instantaneous Reactive Power Theory
CN109742758A (en) A kind of APF compensation method based on Dyn11 transformer
Guo et al. Improved park inverse transform algorithm for positive and negative sequence separation of grid voltage under unbalanced grid conditions
Chen et al. Detection method of grid voltage sag for offshore wind power converter
Niu et al. Research on Linear Active Disturbance Rejection Control Strategy of Single-phase Inverter Constant Current Source

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
GR01 Patent grant
GR01 Patent grant