CN109188084B - Method and system for measuring and distinguishing impedance model of power system - Google Patents
Method and system for measuring and distinguishing impedance model of power system Download PDFInfo
- Publication number
- CN109188084B CN109188084B CN201811005330.4A CN201811005330A CN109188084B CN 109188084 B CN109188084 B CN 109188084B CN 201811005330 A CN201811005330 A CN 201811005330A CN 109188084 B CN109188084 B CN 109188084B
- Authority
- CN
- China
- Prior art keywords
- current
- impedance model
- power frequency
- vector
- phasor
- 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
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
Abstract
The invention discloses a measuring and distinguishing method and a system of an impedance model of a power system, wherein the method comprises the following steps: adjusting port power frequency voltage and port power frequency current to set a steady-state working point, and adding a preset signal harmonic interference source into an equipment port; collecting voltage and current of an equipment port, and calculating power frequency phasor and harmonic phasor of the voltage and the current through Fourier analysis; working condition row vectors are obtained through calculation according to the power frequency voltage current phasor, and the operating working conditions are changed to obtain different coefficient row vectors; obtaining a coefficient matrix according to different coefficient row vectors, expanding the coefficient matrix, and constructing a column vector; and solving the equipment parameters according to the expanded coefficient matrix and the column vector to obtain an impedance model of the equipment. The method effectively realizes accurate calculation of the equipment impedance model under the condition that the operation working condition is constantly changed, and effectively improves the stability of the power system.
Description
Technical Field
The invention relates to the technical field of analysis and control of a power system, in particular to a measuring and distinguishing method and system of an impedance model of the power system.
Background
In recent years, clean renewable energy power generation technologies such as wind power and photovoltaic power generation based on power electronic converters are rapidly developed, and the proportion of power electronic equipment in a power system is greatly increased. The access of high-proportion power electronic equipment increases the unstable factors of the power system, and simultaneously brings challenges to stability analysis correspondingly.
For evaluating the stability of a power system with high power electronization, an impedance model method can be generally adopted. The impedance model analysis method is an accurate and effective method, and the method firstly carries out impedance modeling on each power device in a power system and then converts a complex system into a series-parallel relation among different impedances, thereby greatly reducing the complexity of system stability analysis.
However, as a small signal model, the size of the impedance model of the device is closely related to its operating condition, that is, if the power frequency voltage and current of the grid-connected point port change, the impedance model of the device also changes accordingly, and the change is nonlinear. Therefore, under the condition that the operation condition is constantly changed, if the constant impedance model is used for analyzing the stability of the system, a large error can be caused.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.
Therefore, an object of the present invention is to provide a method for measuring and identifying an impedance model of an electrical power system, which effectively realizes accurate calculation of an impedance model of equipment under a condition that an operation condition is constantly changed, and effectively improves the stability of the electrical power system.
Another object of the present invention is to provide a system for identifying an impedance model of an electrical power system.
In order to achieve the above object, an embodiment of the present invention provides a method for measuring and identifying an impedance model of an electrical power system, in which device parameters and operating conditions in the impedance model of the electrical power system are decoupled so as to determine the impedance model according to grid-connected point conditions, where the method includes the following steps: adjusting port power frequency voltage and port power frequency current to set a steady-state working point, and adding a preset signal harmonic interference source into an equipment port; collecting voltage and current of the equipment port, and calculating power frequency phasor and harmonic phasor of the voltage and the current through Fourier analysis; working condition row vectors are obtained through calculation according to the power frequency voltage current phasor, and the operating working conditions are changed to obtain different coefficient row vectors; obtaining a coefficient matrix according to the different coefficient row vectors, expanding the coefficient matrix, and constructing a column vector; and solving the equipment parameters according to the expanded coefficient matrix and the column vector to obtain an impedance model of the equipment.
According to the method for measuring and distinguishing the impedance model of the power system, the device parameters and the operation conditions in the impedance model are decoupled, so that in the actual operation process of the device, if the device parameters are known, the impedance model can be determined only by measuring the grid-connected point conditions, the device parameters are measured and calculated, the values of the device parameters are determined, the impedance model of the device is further determined, accurate calculation of the impedance model of the device under the condition that the operation conditions are constantly changed is effectively achieved, and the stability of the power system is effectively improved.
In addition, the method for measuring and identifying the impedance model of the power system according to the above embodiment of the present invention may further have the following additional technical features:
further, in an embodiment of the present invention, the obtaining an impedance model of the device further includes: under any working condition, detecting the voltage and the current of the equipment port to obtain the power frequency voltage and the current phasor of the working condition; and substituting the equipment parameters into a first formula to obtain a first vector, substituting the power frequency voltage and current phasor of the working condition and the first vector into a second formula to obtain a working condition row vector and an equipment parameter matrix, and obtaining the impedance model according to the first vector, the working condition row vector and the equipment parameter matrix through a third formula.
Further, in one embodiment of the present invention, the first formula is:
wherein x isisk、yisk、xick、yick、xvsk、yvsk、xvck、yvck、αvsk、βvsk、αvck、βvckAre all equipment parameters, where k is 1,2,3, 4.
Further, in one embodiment of the present invention, the second formula is:
wherein, O is a working condition row vector,
is the power frequency voltage phasor, and the power frequency voltage phasor is obtained,
is the phase quantity of the power frequency current,
the conjugate value of the power frequency current phasor; p0、P11、P12、P21And P22Is a device parameter matrix; x is the number ofis，xic，xvs，xvc，yis，yic，yvs，yvc，αvs，αvc，βvs，βvcIs a first vector, upThe corner mark "T" represents a vector transpose; gamma is a phase-locked loop parameter.
Further, in one embodiment of the present invention, the third formula is:
wherein O is a working condition row vector, P0、P11、P12、P21And P22Is a device parameter matrix; y is11，Y12，Y21And Y22In the admittance form of the impedance model.
In order to achieve the above object, an embodiment of another aspect of the present invention provides a system for measuring and identifying an impedance model of an electrical power system, in which device parameters and operating conditions in the impedance model of the electrical power system are decoupled so as to determine the impedance model according to grid-connected point conditions, where the system includes: the signal generation module is used for generating three-phase disturbance harmonic interference and adding the preset signal harmonic interference source into an equipment port; the signal acquisition module is used for acquiring the voltage and the current of the equipment port and calculating the power frequency phasor and the harmonic phasor of the voltage and the current through Fourier analysis; and the impedance parameter calculation module is used for calculating working condition row vectors according to the power frequency voltage and current phasors, obtaining different coefficient row vectors after the working condition is changed, obtaining a coefficient matrix according to the different coefficient row vectors, expanding the coefficient matrix, constructing column vectors, and solving the equipment parameters according to the expanded coefficient matrix and the column vectors so as to obtain the impedance model of the equipment.
According to the measuring and distinguishing system of the impedance model of the power system, provided by the embodiment of the invention, the device parameters and the operation conditions in the impedance model are decoupled, so that in the actual operation process of the device, if the device parameters are known, the impedance model can be determined only by measuring the grid-connected point conditions, and the device parameters are measured and calculated to determine the values of the device parameters, so that the impedance model of the device is further determined, therefore, the accurate calculation of the impedance model of the device under the condition that the operation conditions are constantly changed is effectively realized, and the stability of the power system is effectively improved.
In addition, the measurement and identification system of the impedance model of the power system according to the above embodiment of the present invention may further have the following additional technical features:
further, in an embodiment of the present invention, the impedance parameter calculation module is further configured to detect a voltage and a current of the device port under any working condition to obtain a power frequency voltage and a current phasor of the working condition, substitute the device parameter into a first formula to obtain a first vector, substitute the power frequency voltage, the current phasor of the working condition and the first vector into a second formula to obtain a working condition row vector and a device parameter matrix, and obtain the impedance model according to the first vector, the working condition row vector and the device parameter matrix by a third formula.
Further, in one embodiment of the present invention, the first formula is:
wherein x isisk、yisk、xick、yick、xvsk、yvsk、xvck、yvck、αvsk、βvsk、αvck、βvckAre all equipment parameters, where k is 1,2,3, 4.
Further, in one embodiment of the present invention, the second formula is:
wherein, O is a working condition row vector,
is the power frequency voltage phasor, and the power frequency voltage phasor is obtained,
is the phase quantity of the power frequency current,
the conjugate value of the power frequency current phasor; p0、P11、P12、P21And P22Is a device parameter matrix; x is the number ofis，xic，xvs，xvc，yis，yic，yvs，yvc，αvs，αvc，βvs，βvcFor the first vector, the superscript "T" represents the vector transpose; gamma is a phase-locked loop parameter.
Further, in one embodiment of the present invention, the third formula is:
wherein O is a working condition row vector, P0、P11、P12、P21And P22Is a device parameter matrix; y is11，Y12，Y21And Y22In the admittance form of the impedance model.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a flow diagram of a method for identifying an impedance model of a power system, according to one embodiment of the invention;
FIG. 2 is a schematic diagram of a system for identifying impedance models of an electrical power system, according to one embodiment of the present invention;
FIG. 3 is a schematic diagram of a system for identifying impedance models of an electrical power system according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
The method and system for determining the impedance model of the power system according to the embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a flow chart of a method for identifying an impedance model of a power system according to an embodiment of the present invention.
As shown in fig. 1, in the method for measuring and identifying the impedance model of the power system, the device parameters and the operating conditions in the impedance model of the power system are decoupled so as to determine the impedance model according to the conditions of the grid-connected point, wherein the method comprises the following steps:
in step S101, port power frequency voltage and port power frequency current are adjusted to set a steady-state operating point, and a preset signal harmonic interference source is added to the device port.
It can be understood that the embodiment of the invention sets the steady-state operating point, namely, adjusts the power frequency voltage of the port
Electric current
A small-signal harmonic interference source is added to an equipment port, for example, a harmonic voltage source or a harmonic current source can be generally adopted; the amplitude of the interference signal is about 1% -10% of the power frequency amplitude, and can generally adopt 5% of the power frequency amplitude.
In step S102, the voltage and current at the device port are collected, and the power frequency phasor and the harmonic phasor of the voltage and current are calculated through fourier analysis.
It can be understood that the embodiment of the invention collects the voltage and current data of the port of the equipment, and calculates the power frequency phasor and the harmonic phasor contained in the voltage and the current through Fourier analysis, wherein the power frequency phasorVoltage and current phasors used respectively
And
showing that the harmonic phasor contains two different frequencies fsAnd fcWherein the frequency is fsRespectively using voltage and current phasors
Anddenotes a frequency fcRespectively using voltage and current phasors
And
and (4) showing. The phasor can use a per unit value, or a famous value, and when the famous value is used, the unit of voltage and current can use kilovolt (kV) and kiloampere (kA), or the unit of voltage (V) and ampere (A);
in step S103, a working condition row vector is obtained by calculation according to the power frequency voltage current phasor, and the operating condition is changed to obtain different coefficient row vectors.
It can be understood that the embodiment of the invention obtains the row vector z by calculation according to the power frequency voltage current phasoropWherein
And calculating to obtain a coefficient row vector a containing 28 elements1Wherein
Changing the operation condition, repeating step S102 to obtain different coefficient row vectors a2～aN。
In step S104, a coefficient matrix is obtained from different coefficient row vectors, the coefficient matrix is expanded, and a column vector is constructed.
It will be appreciated that the coefficient row vector akN, k being 1,2, …, form a coefficient matrix a, where a being [ a ═ a1；a2；…,aN](ii) a Calculating the rank of the matrix A, if the rank is greater than or equal to 26, expanding the coefficient matrix A, and after expansion, setting the matrix A' as [ A; e.g. of the typei；ej]And satisfies A' is 28, wherein ei、ejUnit row vectors of the ith element and the jth element which are respectively 1 and the rest elements which are 0; if the rank is less than 26, changing the operation condition, repeating the steps S102 and S103, and obtaining more different coefficient row vectors an，n>N。
In addition, the embodiment of the present invention constructs a column vector b as [0 ═ 01×N,d1,d2]TWherein d is1，d2It may be any constant not being 0 at the same time, and d may be generally selected1＝1，d20 or d1＝0，d2＝1；
Selecting a group d1And d2And solving the equation set. For example when d1＝1，d2When 0, solve the system of equations a' x b to get x, where x is xI,xII,xIII,xIV]T，
Selecting another group d which is linearly independent1And d2And solving the equation set. For example when d1＝0，d2When the value is 1, solving the equation set A' y b to obtain y, wherein y is [ y ═ bI,yII,yIII,yIV]T，
In step S105, the device parameters are solved according to the expanded coefficient matrix and the column vector, so as to obtain an impedance model of the device.
In one embodiment of the present invention, obtaining an impedance model of a device further comprises: under any working condition, detecting the voltage and current of the equipment port to obtain the power frequency voltage and current phasor of the working condition; and substituting the equipment parameters into a first formula to obtain a first vector, substituting the power frequency voltage and current phasor of the working condition and the first vector into a second formula to obtain a working condition row vector and an equipment parameter matrix, and obtaining the impedance model according to the first vector, the working condition row vector and the equipment parameter matrix through a third formula.
It is understood that the embodiment of the present invention further solves γ, x according to the formula 1 and the formula 2isk，xick，xvsk，xvck，αvsk，αvck，yisk，yick，yvsk，yvck，βvsk，βvckAnd k is 1,2,3,4 and other equipment parameters. The calculation method of the impedance model comprises the following steps:
1) under any working condition, firstly measuring the voltage and current data of the equipment port, and calculating the power frequency voltage and current phasor
And
2) will be in working condition
And
substituting the formula second formula to obtain a working condition row vector O, substituting the obtained equipment parameter into the formula first formula, and substituting the obtained equipment parameter into the formula second formula to obtain P0，P11，P12，P21，P22Finally, O and P are added0，P11，P12，P21，P22Substituting the third formula to obtain the impedance model of the equipment.
In one embodiment of the present invention, the first formula is:
wherein x isisk、yisk、xick、yick、xvsk、yvsk、xvck、yvck、αvsk、βvsk、αvck、βvckAre all equipment parameters, where k is 1,2,3, 4.
Further, in one embodiment of the present invention, the second formula is:
wherein, O is a working condition row vector,
is the power frequency voltage phasor, and the power frequency voltage phasor is obtained,
is the phase quantity of the power frequency current,
the conjugate value of the power frequency current phasor; p0、P11、P12、P21And P22Is a device parameter matrix; x is the number ofis，xic，xvs，xvc，yis，yic，yvs，yvc，αvs，αvc，βvs，βvcFor the first vector, the superscript "T" represents the vector transpose; gamma is a phase-locked loop parameter.
Further, in one embodiment of the present invention, the third formula is:
wherein O is the working conditionLine vector, P0、P11、P12、P21And P22Is a device parameter matrix; y is11，Y12，Y21And Y22In the admittance form of the impedance model.
Specifically, the solution of the impedance model with decoupled device parameters and operating conditions is as follows:
for a power device, the small signal input-output relationship under a specific working condition is represented by the following impedance model:
wherein: the matrix Y of 2 x 2 orders is the admittance form of the impedance model;
and
representing the frequency f in the voltage and current of the equipment portsThe phasor of the harmonic wave of (a),
andrepresenting the frequency f in the voltage and current of the equipment portcThe frequency of the harmonic component satisfies fs+fc＝2f1(ii) a "+" indicates taking the conjugate of the phasor, i.e.
Andare respectively
And
conjugation of (1).
After decoupling the plant parameters from the operating conditions, each admittance can be represented using the following equation 4:
wherein the content of the first and second substances,
wherein the content of the first and second substances,
and
the power frequency voltage and current of the grid-connected point are respectively defined as:
wherein, V1Is the power frequency voltage amplitude, I1Is the power frequency current amplitude, phii1The phase of the power frequency current relative to the power frequency voltage.
Wherein, in the formula 4,
in the formula 7, the first and second groups,
note that x in equation 8isk,yisk,xick,yick,xvsk,yvsk,xvck,yvck,αvsk,βvsk,αvck,βvckAnd k is 1,2,3,4, etc. all are equipment parameters, namely, the control strategy and the control parameters of the controller are determinedThe values of these parameters are independent of the operating conditions, i.e. of the port voltage, of the specific equipment
Electric currentIs irrelevant.
The decoupling of the equipment parameters and the operation conditions is realized by the impedance model with the decoupling of the equipment parameters and the operation conditions, namely, the impedance model can be accurately calculated when the operation conditions change under the condition that the equipment parameters are determined, and the problem that the traditional impedance model is difficult to accurately obtain along with the change of the operation conditions is solved.
Further, when the linear equation set a ' x ═ b or a ' y ═ b is solved in the impedance model measurement and identification method, the matrix a ' is of 28 orders, so that the measurement times are large, and certain difficulty is brought to calculation. After analysis, it can be determined that each item in x or y has the following relationship:
a)xis3,αxis3,xic4,αxic4,xvs2,xvc2,xvs3,xvc4,αvs1,αvc1is 0; y isis3,βyis3,yic4,βyic4,yvs2,yvc2,yvs3,yvc4,βvs1,βvc1Is 0;
b)αvsk＝-αvck,βvsk＝-βvck,k＝1,2,3,4；
according to a) and b), the method for detecting and distinguishing can be simplified, and elements with constant 0 are removed, so that the specific steps of the impedance model simplified method for detecting and distinguishing comprise:
(1) setting steady-state operating points, i.e. adjusting port power-frequency voltage
Electric current
(2) Adding a small-signal harmonic interference source at an equipment port, wherein a harmonic voltage source or a harmonic current source can be generally adopted; the amplitude of the interference signal is about 1% -10% of the power frequency amplitude, and can generally adopt 5% of the power frequency amplitude.
(3) Acquiring voltage and current data of a port of equipment, and calculating power frequency phasor and harmonic phasor contained in the voltage and the current through Fourier analysis, wherein the power frequency voltage phasor and the power frequency current phasor are respectively used
And
showing that the harmonic phasor contains two different frequencies fsAnd fcWherein the frequency is fsRespectively using voltage and current phasors
And
denotes a frequency fcRespectively using voltage and current phasors
And
and (4) showing. The phasors may use per unit values, or by using known values, where kilovolts (kV) and kiloamperes (kA) or volts (V) and amperes (a) may be used for voltage and current units.
(4) Calculating to obtain a row vector z according to the power frequency voltage and current phasorsopWhereinAnd calculating to obtain a coefficient row vector a containing 28 elements1Wherein
(5) Changing the operation condition, repeating (2) - (4) to obtain different coefficient row vectors a2～aN。
(6) Coefficient row vector akN, k being 1,2, …, form a coefficient matrix a, where a being [ a ═ a1；a2；…,aN](ii) a Simplifying the matrix A, and removing the 3 rd, 6 th, 11 th, 14 th, 19 th, 20 th, 26 th and 28 th columns of the matrix A to obtain the simplified A1Calculating the matrix A1If the rank is greater than or equal to 18, proceed to (7), otherwise, continue to (5).
(7) Expansion coefficient matrix A1Expanded matrix A2＝[A1；ei；ej]And satisfy A2Is 20, wherein ei、ejThe unit row vectors are respectively the ith and jth elements as 1, and the rest elements as 0.
(8) Construct column vector b ═ 01×N,d1,d2]TWherein d is1，d2It may be any constant not being 0 at the same time, and d may be generally selected1＝1，d20 or d1＝0，d2＝1；
Selecting a group d1And d2And solving the equation set. For example when d1＝1，d2When 0, solve the system of equations A2x ═ b, yielding x, where x ═ xI,xII,xIII,xIV]T，
Selecting another group d which is linearly independent1And d2And solving the equation set. For example when d1＝0，d2When the value is 1, solving the equation set A' y b to obtain y, wherein y is [ y ═ bI,yII,yIII,yIV]T，
(9) Further solution according to equations 9 and 10Goes out of gamma, xisk，xick，xvsk，xvck，αvsk，αvck，yisk，yick，yvsk，yvck，βvsk，βvckAnd k is 1,2,3,4 and other equipment parameters. The calculation method of the impedance model comprises the following steps:
(10) under any working condition, firstly measuring the voltage and current data of the equipment port, and calculating the power frequency voltage and current phasor
And
(11) will be in working conditionAnd
substituting formula 5 to obtain operating condition row vector O, substituting formula 8 with the equipment parameters obtained in step (9), and substituting formula 7 to obtain P0，P11，P12，P21，P22Finally, O and P are added0，P11，P12，P21，P22The impedance model of the device can be obtained by substituting the equation 4.
The method for measuring and distinguishing the impedance model of the power system is further described below by way of specific embodiments, and for the electrical equipment of which the impedance model needs to be measured, the method for measuring and distinguishing the impedance model of the power system provided by the embodiments of the present invention is designed and implemented according to the following steps:
step 1: establishing a steady state operating point
An impedance model measuring and distinguishing system is constructed according to the figure 2, and a data acquisition module is configured to ensure enough sampling frequency and sampling time. And adjusting the power grid impedance and the control reference value of the power equipment to enable the power equipment to reach a steady-state working point.
Step 2: applying a perturbation signal
Configuring a signal generation module to obtain a proper disturbance voltage source uhOr a disturbance current source ihAnd the same time axis as the data acquisition module is adopted as much as possible, so that the impedance model can be conveniently identified later.
And step 3: collecting data and calculating voltage and current phasors
The data acquisition module is used for recording the voltage and the current of the measuring point in real time, and extracting the power frequency voltage component through Fourier transform
Component of current
Harmonic voltage, current components
And 4, step 4: calculating a row vector a
Calculating to obtain a row vector z according to the power frequency voltage and current phasorsopWherein
And calculating to obtain a coefficient row vector a containing 28 elements1Wherein
Removing the 3 rd, 6 th, 11 th, 14 th, 19 th, 20 th, 26 th and 28 th elements of a to obtain a simplified a1'。
And 5: repeated measurement test
Changing the control reference value and the power grid impedance of the equipment, changing the steady-state operating point (operating condition), the amplitude, the phase and the like of the disturbance signal, repeating the measurement of the step 3-4 to obtain a plurality of groups of data and obtain a plurality of groups of a2'～aN'。
Step 6: obtaining a coefficient matrix
Computing the matrix A1＝[a1'；a2'；…,aN']If the rank is greater than or equal to 18, go to step 7, otherwise, continue the step5。
And 7: expansion coefficient matrix
Expansion matrix A1Adding two unit row vectors (only one non-zero element and 1) to expand the matrix A2Is 20. A. the2＝[A1；ei；ej]Wherein e isiAnd ejThe ith and jth elements of the unit row direction are 1;
two values are selected, d, not all being 011And d12Generally, can be taken d11＝1,d120, structure b1＝[0,…,0,d11,d12]T. Solving for A2x＝b1Its solution is x, x ═ x1,x2,…,x20]T；
Selecting two other values, d, not all being 021And d22Generally, can be taken d21＝0,d221, structure b2＝[0,…,0,d21,d22]T. Solving for A2y＝b2Its solution is y, y ═ y1,y2,…,y20]T。
And 8: calculating device parameters
Solving for γ according to equation 11;
solving other parameters:
xis＝[x1/γ,x4,0,x5]T，xic＝[x6/γ,x9,x10,0]T，xvs＝[x11/γ,0,0,x15]T，xvc＝[x16/γ,0,x20,0]T，αvs＝[0,x12-x11/γ,x13,x14-γx15]T，αvc＝-αvs；yis＝[y1/γ,y4,0,y5]T，yic＝[y6/γ,y9,y10,0]T，yvs＝[y11/γ,0,0,y15]T，yvc＝[y16/γ,0,y20,0]T，βvs＝[0,y12-y11/γ,y13,y14-γy15]T，βvc＝-βvs。
and step 9: calculating an impedance model
The device parameters and the grid-connected point voltage calculated in the step 8 are compared
Electric currentAnd (5) substituting the equations 7, 5 and 4 to obtain an admittance matrix Y of the impedance model.
According to the method for measuring and distinguishing the impedance model of the power system provided by the embodiment of the invention, the device parameters and the operation conditions in the impedance model are decoupled, so that in the actual operation process of the device, if the device parameters are known, the impedance model can be determined only by measuring the grid-connected point conditions, the measurement and calculation of the device parameters are also carried out, and the values of the device parameters are determined, so that the impedance model of the device is further determined, therefore, the accurate calculation of the impedance model of the device under the condition that the operation conditions are constantly changed is effectively realized, and the stability of the power system is effectively improved.
Next, a description will be given of a measurement system of an impedance model of an electric power system according to an embodiment of the present invention with reference to the drawings.
FIG. 3 is a schematic diagram of a system for identifying impedance models of an electrical power system according to an embodiment of the present invention.
As shown in fig. 3, in the identification system of the impedance model of the power system, the device parameters and the operation conditions in the impedance model of the power system are decoupled, so as to determine the impedance model according to the grid-connected point conditions, wherein the system 10 includes: the system comprises a signal generation module 100, a signal acquisition module 200 and an impedance parameter calculation module 300.
The signal generating module 100 is configured to generate three-phase disturbance harmonic interference, and add the preset signal harmonic interference source to the device port. The signal acquisition module 200 is used for acquiring voltage and current of the equipment port, and calculating power frequency phasor and harmonic phasor of the voltage and the current through Fourier analysis. The impedance parameter calculation module 300 is configured to obtain a working condition row vector according to the power frequency voltage current phasor calculation, obtain different coefficient row vectors after the working condition changes, obtain a coefficient matrix according to the different coefficient row vectors, expand the coefficient matrix, construct a column vector, and solve the device parameter according to the expanded coefficient matrix and column vector to obtain an impedance model of the device. The system 10 of the embodiment of the invention effectively realizes the accurate calculation of the equipment impedance model under the condition that the operation condition is constantly changed, and effectively improves the stability of the power system.
Specifically, as shown in fig. 2, the system 10 includes a signal generation module 100, a signal acquisition module 200, an impedance parameter calculation module 300, and the like. The signal generation module 100 generates a disturbance signal and injects the disturbance signal into the device port; the signal acquisition module 200 acquires voltage and current data at a device port; the impedance parameter calculating module 300 calculates the identification device parameter according to the voltage and current data. The specific functions are as follows:
(1) the signal generation module 100 generates a three-phase disturbance signal, the amplitude of the disturbance signal cannot affect the normal operation of the system, generally is 1% -10% of the amplitude of the power frequency signal of the working point, and 5% of the amplitude of the power frequency signal is recommended to be selected; the frequency, amplitude, initial phase and the like of the disturbance signal can be adjusted according to the requirement.
(2) After the signal acquisition module 200 acquires the disturbance signal and injects the disturbance signal into the system, the voltage and current waveform data of the equipment port are acquired and stored.
(3) The impedance parameter calculating module 300 calculates the phasor of each frequency in the voltage and the current according to the voltage and the current data stored by the signal acquisition module: voltage at power frequency
Electric current
Harmonic voltage,Component of current
And calculating the equipment parameters and the impedance model according to the measuring and distinguishing method of the impedance model or the simplified measuring and distinguishing method.
Further, in an embodiment of the present invention, the impedance parameter calculation module 300 is further configured to detect a voltage and a current of the device port under any working condition to obtain a power frequency voltage and a current phasor of the working condition, obtain a first vector according to a first formula of the power frequency voltage and the current phasor of the working condition, substitute the device parameter into a second formula and the first formula to obtain a working condition row vector and a working condition matrix, and obtain the impedance model according to the first vector, the working condition row vector, and the working condition matrix by a third formula.
Further, in one embodiment of the present invention, the first formula is:
wherein x isisk、yisk、xick、yick、xvsk、yvsk、xvck、yvck、αvsk、βvsk、αvck、βvckAre all equipment parameters, where k is 1,2,3, 4.
Further, in one embodiment of the present invention, the second formula is:
wherein, O is a working condition row vector,
is the power frequency voltage phasor, and the power frequency voltage phasor is obtained,
is the phase quantity of the power frequency current,
the conjugate value of the power frequency current phasor; p0、P11、P12、P21And P22Is a device parameter matrix; x is the number ofis，xic，xvs，xvc，yis，yic，yvs，yvc，αvs，αvc，βvs，βvcFor the first vector, the superscript "T" represents the vector transpose; gamma is a phase-locked loop parameter.
Further, in one embodiment of the present invention, the third formula is:
wherein O is a working condition row vector, P0、P11、P12、P21And P22Is a device parameter matrix; y is11，Y12，Y21And Y22In the admittance form of the impedance model.
It should be noted that the explanation of the embodiment of the method for determining an impedance model of an electric power system is also applicable to the determination system of the impedance model of the electric power system of the embodiment, and is not repeated herein.
According to the measuring and distinguishing system of the impedance model of the power system, provided by the embodiment of the invention, the decoupling of the equipment parameters and the operation conditions in the impedance model is realized, and in the actual operation process of the equipment, if the equipment parameters are known, the impedance model can be determined only by measuring the grid-connected point conditions, and the measurement and calculation of the equipment parameters are also carried out, so that the value of the equipment parameters is determined, the impedance model of the equipment is further determined, the accurate calculation of the impedance model of the equipment under the condition that the operation conditions are constantly changed is effectively realized, and the stability of the power system is effectively improved.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., 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 invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A method for measuring and distinguishing an impedance model of an electric power system is characterized in that equipment parameters and operation conditions in the impedance model of the electric power system are decoupled so as to determine the impedance model according to grid-connected point conditions, wherein the method comprises the following steps:
adjusting port power frequency voltage and port power frequency current to set a steady-state working point, and adding a preset signal harmonic interference source into an equipment port;
collecting voltage and current of the equipment port, and calculating power frequency phasor and harmonic phasor of the voltage and the current through Fourier analysis;
working condition row vectors are obtained through calculation according to the power frequency voltage current phasor, and the operating working conditions are changed to obtain different coefficient row vectors;
obtaining a coefficient matrix according to the different coefficient row vectors, expanding the coefficient matrix, and constructing a column vector; and
and solving the equipment parameters according to the expanded coefficient matrix and the column vector to obtain an impedance model of the equipment.
2. The method of claim 1, wherein the obtaining the impedance model of the device further comprises:
under any working condition, detecting the voltage and the current of the equipment port to obtain the power frequency voltage and the current phasor of the working condition;
substituting the equipment parameters into a first formula to obtain a first vector, and substituting the power frequency voltage, the current phasor and the first vector of the working condition into a second formula to obtain a working condition row vector and an equipment parameter matrix;
and obtaining the impedance model through a third formula according to the first vector, the working condition row vector and the equipment parameter matrix.
3. The method of claim 2, wherein the step of determining the impedance of the power system comprises,
the first formula is:
wherein x isisk、yisk、xick、yick、xvsk、yvsk、xvck、yvck、αvsk、βvsk、αvckAnd βvckAre all equipment parameters, where k is 1,2,3, 4.
4. The method of claim 3, wherein the step of determining the impedance of the power system comprises,
the second formula is:
wherein, O is a working condition row vector,
is the power frequency voltage phasor, and the power frequency voltage phasor is obtained,
is the phase quantity of the power frequency current,
the conjugate value of the power frequency current phasor; p0、P11、P12、P21And P22Is a device parameter matrix; x is the number ofis、xic、xvs、xvc、yis、yic、yvs、yvc、αvs、αvc、βvsAnd βvcFor the first vector, the superscript "T" represents the vector transpose; gamma is a phase-locked loop parameter.
5. The method of claim 4, wherein the step of determining the impedance of the power system comprises,
the third formula is:
wherein O is a working condition row vector, P0、P11、P12、P21And P22Is a device parameter matrix; y is11，Y12，Y21And Y22In the admittance form of the impedance model.
6. A system for measuring and distinguishing an impedance model of a power system, wherein equipment parameters and operating conditions in the impedance model of the power system are decoupled so as to determine the impedance model according to grid-connected point conditions, wherein the system comprises:
the signal generation module is used for generating three-phase disturbance harmonic interference and adding a preset signal harmonic interference source into an equipment port;
the signal acquisition module is used for acquiring the voltage and the current of the equipment port and calculating the power frequency phasor and the harmonic phasor of the voltage and the current through Fourier analysis; and
and the impedance parameter calculation module is used for calculating to obtain a working condition row vector according to the power frequency voltage current phasor, calculating to obtain different coefficient row vectors after the working condition is changed, obtaining a coefficient matrix according to the different coefficient row vectors, expanding the coefficient matrix, constructing a column vector, and solving the equipment parameters according to the expanded coefficient matrix and the column vector so as to obtain the impedance model of the equipment.
7. The system of claim 6, wherein the impedance parameter calculation module is further configured to detect a voltage and a current at the device port under any operating condition to obtain a power frequency voltage and a current phasor of the operating condition, substitute the device parameter into a first formula to obtain a first vector, substitute the power frequency voltage and the current phasor of the operating condition and the first vector into a second formula to obtain an operating condition row vector and a device parameter matrix, and obtain the impedance model according to the first vector, the operating condition row vector and the device parameter matrix by using a third formula.
8. The identification system of the impedance model of the power system according to claim 7,
the first formula is:
wherein x isisk、yisk、xick、yick、xvsk、yvsk、xvck、yvck、αvsk、βvsk、αvckAnd βvckAre all equipment parameters, where k is 1,2,3, 4.
9. The identification system of the impedance model of the power system according to claim 8,
the second formula is:
wherein, O is a working condition row vector,
is the power frequency voltage phasor, and the power frequency voltage phasor is obtained,is the phase quantity of the power frequency current,
the conjugate value of the power frequency current phasor; p0、P11、P12、P21And P22Is a device parameter matrix; x is the number ofis、xic、xvs、xvc、yis、yic、yvs、yvc、αvs、αvc、βvsAnd βvcFor the first vector, the superscript "T" represents the vector transpose; gamma is a phase-locked loop parameter.
10. The identification system of the impedance model of the power system according to claim 9,
the third formula is:
wherein O is a working condition row vector, P0、P11、P12、P21And P22Is a device parameter matrix; y is11，Y12，Y21And Y22In the admittance form of the impedance model.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811005330.4A CN109188084B (en) | 2018-08-30 | 2018-08-30 | Method and system for measuring and distinguishing impedance model of power system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811005330.4A CN109188084B (en) | 2018-08-30 | 2018-08-30 | Method and system for measuring and distinguishing impedance model of power system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109188084A CN109188084A (en) | 2019-01-11 |
| CN109188084B true CN109188084B (en) | 2020-02-04 |
Family
ID=64917118
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811005330.4A Active CN109188084B (en) | 2018-08-30 | 2018-08-30 | Method and system for measuring and distinguishing impedance model of power system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109188084B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109782068B (en) * | 2019-01-21 | 2021-02-23 | 清华大学 | Broadband impedance scanning method and system based on real-time digital simulator |
| CN110866338B (en) * | 2019-11-13 | 2021-08-17 | 清华大学 | Method and device for solving apparent impedance model based on coupling impedance model |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104007321A (en) * | 2014-06-17 | 2014-08-27 | 华北电力大学（保定） | Method for online identification of parameters of reactive compensation capacitor bank |
| CN107402334A (en) * | 2017-07-10 | 2017-11-28 | 清华大学 | The frequency domain identification method and system of power system time/supersynchronous coupled impedance model |
| CN107994605A (en) * | 2017-11-27 | 2018-05-04 | 浙江大学 | A kind of grid-connected inverter system method for analyzing stability based on harmonics matrix transmission function |
| CN107994586A (en) * | 2017-09-07 | 2018-05-04 | 国网山东省电力公司淄博供电公司 | A kind of high and low pressure network voltage dynamic response decoupling method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2506626B (en) * | 2012-10-03 | 2018-02-07 | Imperial Innovations Ltd | Frequency estimation |
-
2018
- 2018-08-30 CN CN201811005330.4A patent/CN109188084B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104007321A (en) * | 2014-06-17 | 2014-08-27 | 华北电力大学（保定） | Method for online identification of parameters of reactive compensation capacitor bank |
| CN107402334A (en) * | 2017-07-10 | 2017-11-28 | 清华大学 | The frequency domain identification method and system of power system time/supersynchronous coupled impedance model |
| CN107994586A (en) * | 2017-09-07 | 2018-05-04 | 国网山东省电力公司淄博供电公司 | A kind of high and low pressure network voltage dynamic response decoupling method |
| CN107994605A (en) * | 2017-11-27 | 2018-05-04 | 浙江大学 | A kind of grid-connected inverter system method for analyzing stability based on harmonics matrix transmission function |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109188084A (en) | 2019-01-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102998535B (en) | Method for computing harmonic impedance of system based on maximum likelihood estimation theory | |
| CN104050366B (en) | A kind of dynamic reactive compensation device response time method of testing | |
| CN107453351B (en) | Power distribution network operation topology identification method based on node injection power | |
| CN108414872A (en) | A kind of earth-fault detecting method for adjusting power source system for power plant's system | |
| CN107402334B (en) | Electric system time/supersynchronous coupled impedance model frequency domain identification method and system | |
| Khoshkhoo et al. | On-line dynamic voltage instability prediction based on decision tree supported by a wide-area measurement system | |
| CN101349731B (en) | Real time evaluating method of voltage stability | |
| CN105938578A (en) | Large-scale photovoltaic power station equivalent modeling method based on clustering analysis | |
| CN103345162A (en) | Power level digital-analog hybrid simulation system | |
| CN105548781A (en) | Bus short-circuit capacity testing method, device and system | |
| CN109188084B (en) | Method and system for measuring and distinguishing impedance model of power system | |
| CN110348114B (en) | Non-precise fault identification method for power grid completeness state information reconstruction | |
| CN109523165A (en) | A kind of voltage dip situation estimation method based on limited information | |
| CN109193635A (en) | A kind of power distribution network topological structure method for reconstructing based on adaptive sparse homing method | |
| CN109490630A (en) | A kind of dynamic phasor measurement method based on pencil of matrix | |
| CN113937764A (en) | Low-voltage distribution network high-frequency measurement data processing and topology identification method | |
| CN109659957A (en) | Based on APIT-MEMD low-frequency oscillation of electric power system pattern identification method | |
| CN111654392A (en) | Low-voltage distribution network topology identification method and system based on mutual information | |
| CN103995948A (en) | Oscillation center voltage prediction method based on polynomial model | |
| CN109494743A (en) | The estimation method of electric system mains by harmonics state based on matrix reconstruction | |
| CN108336730B (en) | Thevenin equivalent parameter identification method based on reduced order self-sensitivity | |
| CN103972889B (en) | A kind of distribution line impedance on-line identification method | |
| CN109782068B (en) | Broadband impedance scanning method and system based on real-time digital simulator | |
| CN105701265A (en) | Double-fed wind generator modeling method and apparatus | |
| CN115343535A (en) | System harmonic impedance estimation method based on Kalman filtering |
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 |