CN113162044B - Optimization method and device for frequency measurement of frequency-dependent impulse response (FIR) filter by digital subscriber unit (DN-PMU) - Google Patents
Optimization method and device for frequency measurement of frequency-dependent impulse response (FIR) filter by digital subscriber unit (DN-PMU) Download PDFInfo
- Publication number
- CN113162044B CN113162044B CN202110212367.XA CN202110212367A CN113162044B CN 113162044 B CN113162044 B CN 113162044B CN 202110212367 A CN202110212367 A CN 202110212367A CN 113162044 B CN113162044 B CN 113162044B
- Authority
- CN
- China
- Prior art keywords
- filter
- performance
- bandwidth
- frequency
- optimized
- 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
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/70—Smart grids as climate change mitigation technology in the energy generation sector
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/22—Flexible AC transmission systems [FACTS] or power factor or reactive power compensating or correcting units
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Filters That Use Time-Delay Elements (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
The invention discloses an optimization method and device of an FIR filter for realizing frequency measurement by DN-PMU, wherein the method comprises the following steps: the differential passband performance, the stop band performance of each subharmonic and the full-band anti-noise performance of the filter to be optimized are respectively represented by technical indexes; establishing a cost function according to the characterized technical indexes; determining the order, fundamental wave bandwidth and each subharmonic bandwidth of a filter to be optimized according to PMU standards; bringing the cost function, the order of the filter to be optimized, the fundamental wave bandwidth and the bandwidth of each subharmonic into a calculation formula to generate an optimization problem containing constraint; solving the optimization problem containing the constraint, and optimizing the filter to be optimized according to the solving result. Aiming at severe three-phase imbalance of a power distribution network and a severe signal environment containing a large amount of harmonic waves and noise, the method can effectively inhibit the influence of the harmonic waves and the noise on frequency measurement, and realizes quick and high-accuracy measurement of the frequency of the power distribution network.
Description
Technical Field
The invention relates to the technical field of electromagnetic measuring instruments, in particular to an optimization method and device of an FIR filter for realizing frequency measurement by DN-PMU.
Background
The synchronous phasor measurement unit (Distribution Network Phasor Measurement Unit, DN-PMU) of the distribution network is a basic unit of the intelligent distribution network measurement system, and has the main functions of measuring the physical quantities such as the synchronous phasor and the frequency of the voltage and the current of the distribution network at the node in real time, transmitting the data of each node to the wide area measurement system (Wide Area Measurement System, WAMS) and providing information support for the monitoring, the control, the protection and the like of the distribution network. With more renewable energy sources (such as wind power and photovoltaic power generation) and energy storage equipment being connected into a power distribution network, the operation mode of the power distribution network presents new complex forms of multi-element interaction, bidirectional tide, potential micro-grids and the like, and the operation and control of the power grid are severely struggled. The DN-PMU technology is used for providing sufficient and reliable information support for the state monitoring, control and protection of the power distribution network.
DN-PMU was developed based on conventional PMU technology applied to the power transmission network. Conventional PMUs have experienced thirty years of development and are well established in technology. Currently, PMU devices are mass assembled in domestic and foreign main grids, and PMU measurement standards are subject to multiple revisions, and the current latest PMU international measurement standard is IEEE C37.118.1-2011 and its revisions IEEE c37.118.1a-2014. In contrast to PMUs, DN-PMUs are in a fast-evolving stage, the technology is not fully mature, and unified DN-PMU measurement standards are not currently established. DN-PMU is more difficult to design in measurement algorithm than PMU: on the one hand, because the distribution network faces a worse signal environment (strong harmonics, strong noise, three-phase imbalance, etc.), on the other hand, some technical indicators of DN-PMUs are more severe than PMUs. Taking frequency measurement as an example, in a power transmission network, as three-phase voltage and current have good symmetry, the measurement accuracy of the positive sequence phasors is little influenced by factors such as power network harmonic waves and frequency fluctuation, and the high-accuracy measurement of the frequency can be realized by simply differentiating the measured positive sequence phasor phase sequences. However, in the power distribution network, due to the lack of three-phase symmetry, or only single-phase signals, harmonic waves, noise, frequency fluctuation and other factors can be obtained, so that a great error is caused to the positive sequence (or single-phase) phase measurement, if a simple differential method is adopted in the DN-PMU frequency measurement for the measured positive sequence (or single-phase) phasor phase sequence, the frequency measurement accuracy can not be ensured.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems in the related art to some extent.
Therefore, one purpose of the invention is to provide an optimization method of an FIR filter for realizing frequency measurement by DN-PMU, which aims at severe three-phase imbalance of a power distribution network and severe signal environment containing a large amount of harmonic waves and noise, can effectively inhibit the influence of the harmonic waves and noise on the frequency measurement, and realizes rapid and high-accuracy measurement of the frequency of the power distribution network.
Another object of the present invention is to propose an optimization device of an FIR filter for frequency measurement by DN-PMU.
In order to achieve the above objective, an embodiment of an aspect of the present invention provides a method for optimizing an FIR filter for implementing frequency measurement by DN-PMU, including:
the differential passband performance, the stop band performance of each subharmonic and the full-band anti-noise performance of the filter to be optimized are respectively represented by technical indexes;
establishing a cost function according to the characterized technical indexes;
determining the order, fundamental wave bandwidth and each subharmonic bandwidth of the filter to be optimized according to PMU standard;
carrying the cost function, the order, the fundamental wave bandwidth and the subharmonic bandwidth of the filter to be optimized into a calculation formula to generate an optimization problem containing constraint;
and solving the optimization problem containing the constraint, and optimizing the filter to be optimized according to a solving result.
According to the optimization method of the FIR filter for realizing frequency measurement by the DN-PMU, which is disclosed by the embodiment of the invention, the length of the actual filter is limited due to the fact that the PMU measurement rapidly responds to the requirement, and the ideal frequency characteristic cannot be realized. According to the signal environment of the power distribution network and DN-PMU measurement characteristics, on the premise of ensuring passband differential characteristics preferentially, harmonic suppression is focused, and then the anti-noise performance is considered. Therefore, the limited data window can be utilized to the maximum extent, various performance indexes are considered, and the rapid and accurate measurement of the frequency is realized.
In addition, the optimization method of the FIR filter for realizing frequency measurement by using the DN-PMU 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 characterizing the differential passband performance, the impedance band performance of each sub-harmonic, and the full-band anti-noise performance of the filter to be optimized with technical indexes includes:
wherein delta 1 For differential passband performance of the filter, H (e jω ) For the frequency response characteristics of the filter to be optimized, ω1 is the normalized bandwidth of the fundamental wave, δ q Omega for each subharmonic stop band performance 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s For the sampling frequency of the synchronous phasor measurement unit of the distribution network, Δω q ＝2πB q /f s Normalized bandwidth for q-th harmonic, B q For the q-order harmonic bandwidth, G n Is the full-band anti-noise performance.
Further, in an embodiment of the present invention, the establishing a cost function according to the characterized technical index includes:
wherein W is p Weight coefficient for differential passband performance, W h Is the harmonic stop band performance weighting coefficient, W n Is of full frequencyWeight coefficient of section anti-noise performance, H (e jω ) For the frequency response characteristic of the filter to be optimized omega 1 Normalized bandwidth for fundamental wave, delta q Omega for each subharmonic stop band performance 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s For the sampling frequency of a synchronous phase measuring unit of a power distribution network, delta omega q ＝2πB q /f s Normalized bandwidth for q-th harmonic, B q Is the q-th harmonic bandwidth.
Further, in one embodiment of the present invention, the optimization problem including constraints is:
wherein α= (α) 1 ,L,α M/2 ) M is the filter order, W p Weight coefficient for differential passband performance, W h The harmonic resistance is provided with a performance weight coefficient, W n Is the weight coefficient of the full-band anti-noise performance, ωp normalized bandwidth for p-th harmonic, alpha k Is the independent variable of the objective function, k is the sum coefficient omega 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s For sampling frequency of synchronous phasor measurement unit of power distribution network, delta omega q ＝2πB q /f s Normalized bandwidth for q-th harmonic, B q Is the q-th harmonic bandwidth.
Further, in an embodiment of the present invention, solving the optimization problem including constraints, and optimizing the filter to be optimized according to a solution result includes:
definition:
wherein lambda is Lagrange eigenvalue, alpha k An argument for an objective function;
order theFinally, the equation set is obtained as
Wherein the method comprises the steps of
Solving the linear equation set to obtain alpha= (alpha) 1 ,L,α M/2 ) According to alpha= (alpha) 1 ,L,α M/2 ) Optimizing the filter to be optimized, wherein the filter to be optimized is
Further, in one embodiment of the invention, determining the order of the filter to be optimized based on PMU criteria includes: according to PMU measurement standard and harmonic suppression function filter of filter to be optimized, the filter to be optimized has notch effect at integral multiple frequency of fundamental wave, length of the filter to be optimizedAt 1/f 0 ～2.5/f 0 Between them.
Further, in one embodiment of the invention, determining the fundamental bandwidth and the respective subharmonic bandwidths from the PMU standard includes: the q-order harmonic frequency is q times of the fundamental wave frequency, requiring B q ＝q×B，B q The q-th harmonic bandwidth and B the fundamental bandwidth.
To achieve the above objective, another embodiment of the present invention provides an optimization apparatus for an FIR filter for implementing frequency measurement by DN-PMU, including:
the characterization module is used for respectively characterizing the differential passband performance, the stop band performance of each subharmonic and the full-band anti-noise performance of the filter to be optimized by using technical indexes;
the establishing module is used for establishing a cost function according to the characterized technical indexes;
the parameter selection module is used for determining the order, the fundamental wave bandwidth and each harmonic bandwidth of the filter to be optimized according to PMU standards;
the generating module is used for bringing the cost function, the order of the filter to be optimized, the fundamental wave bandwidth and each subharmonic bandwidth into a calculation formula to generate an optimization problem containing constraint;
the optimization module is used for solving the optimization problem containing the constraint and optimizing the filter to be optimized according to the solving result
According to the optimizing device of the FIR filter for realizing frequency measurement by the DN-PMU, which is disclosed by the embodiment of the invention, the length of the actual filter is limited due to the fact that the PMU measurement rapidly responds to the requirement, and the ideal frequency characteristic cannot be realized. According to the signal environment of the power distribution network and DN-PMU measurement characteristics, on the premise of ensuring passband differential characteristics preferentially, harmonic suppression is focused, and then the anti-noise performance is considered. Therefore, the limited data window can be utilized to the maximum extent, various performance indexes are considered, and the rapid and accurate measurement of the frequency is realized.
In addition, the optimization device of the FIR filter for realizing frequency measurement by using the DN-PMU 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 characterizing the differential passband performance, the impedance band performance of each sub-harmonic, and the full-band anti-noise performance of the filter to be optimized with technical indexes includes:
wherein delta 1 For differential passband performance of the filter, H (e jω ) For the frequency response characteristic of the filter to be optimized omega 1 Normalized bandwidth for fundamental wave, delta q Omega for each subharmonic stop band performance 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s For the sampling frequency of the synchronous phasor measurement unit of the distribution network, Δω q ＝2πB q /f s Normalized bandwidth for q-th harmonic, B q For the q-order harmonic bandwidth, G n Is the full-band anti-noise performance.
Further, in an embodiment of the present invention, the establishing a cost function according to the characterized technical index includes:
wherein W is p Weight coefficient for differential passband performance, W h Is the harmonic stop band performance weighting coefficient, W n Weight coefficient for full-band anti-noise performance, H (e jω ) For the frequency response characteristic of the filter to be optimized omega 1 Normalized bandwidth for fundamental wave, delta q Omega for each subharmonic stop band performance 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s For the sampling frequency of a synchronous phase measuring unit of a power distribution network, delta omega q ＝2πB q /f s Normalized bandwidth for q-th harmonic, B q Is the q-th harmonic bandwidth.
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 invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a flow chart of an optimization method of an FIR filter for frequency measurement by DN-PMU according to one embodiment of the present invention;
fig. 2 is a schematic diagram of the filter coefficients of a low-pass digital differential filter for implementing frequency measurement by a distribution network synchronous phasor measurement unit (DN-PMU) according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a frequency response characteristic of a low-pass digital differential filter for implementing frequency measurement by a distribution network synchronous phasor measurement unit (DN-PMU) according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a simulation test of frequency measurement errors of a DN-PMU with a differential three-phase algorithm and a single-phase differential algorithm under a grid frequency offset condition according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a simulation test curve of frequency measurement errors of DN-PMU under the condition of 1% harmonic distortion rate with a differential three-phase algorithm and a single phase difference algorithm according to an embodiment of the invention;
fig. 6 is a schematic diagram of a simulation test of frequency measurement errors of DN-PMU under a condition of 10% harmonic distortion rate with a differential three-phase algorithm and a single-phase differential algorithm according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a simulation test of frequency measurement errors of a DN-PMU under sinusoidal amplitude modulation with a differential three-phase algorithm and a single-phase differential algorithm according to one embodiment of the present invention;
FIG. 8 is a schematic diagram of a simulation test of frequency measurement errors of a DN-PMU under sinusoidal phase modulation with a differential three-phase algorithm and a single-phase differential algorithm according to one embodiment of the present invention;
fig. 9 is a schematic diagram of an optimization device structure of an FIR filter for implementing frequency measurement by DN-PMU according to an embodiment of the invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
The following describes an optimization method and device of an FIR filter for realizing frequency measurement by DN-PMU according to the embodiment of the invention with reference to the accompanying drawings.
An optimization method of an FIR filter for realizing frequency measurement by using a DN-PMU according to an embodiment of the present invention will be described with reference to the accompanying drawings.
Fig. 1 is a flowchart of an optimization method of an FIR filter for implementing frequency measurement by DN-PMU according to an embodiment of the invention.
As shown in fig. 1, the optimization method of the FIR filter for realizing frequency measurement by using the DN-PMU comprises the following steps:
and step S101, the differential passband performance, the stop band performance of each subharmonic and the full-band anti-noise performance of the filter to be optimized are respectively represented by technical indexes.
Specifically, the calculation formula is as follows:
wherein delta 1 For differential passband performance of the filter, H (e jω ) For the frequency response characteristic of the filter to be optimized omega 1 Normalized bandwidth for fundamental wave, delta q Omega for each subharmonic stop band performance 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s For the sampling frequency of the synchronous phasor measurement unit of the distribution network, Δω q ＝2πB q /f s Normalized bandwidth for q-th harmonic, B q Is q-order harmonic bandwidth, unit is Hz, G n Is the full-band anti-noise performance.
Step S102, a cost function is established according to the characterized technical indexes.
Specifically, the calculation formula is as follows:
wherein W is p Weight coefficient for differential passband performance, W h Is the harmonic stop band performance weighting coefficient, W n Weight coefficient for full-band anti-noise performance, H (e jω ) For the frequency response characteristic of the filter to be optimized omega 1 Normalized bandwidth for fundamental wave, delta q Omega for each subharmonic stop band performance 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s For the sampling frequency of a synchronous phase measuring unit of a power distribution network, delta omega q ＝2πB q /f s Normalized bandwidth for q-th harmonic, B q Is the q-th harmonic bandwidth.
Step S103, determining the order, fundamental wave bandwidth and each subharmonic bandwidth of the filter to be optimized according to PMU standard.
Specifically, the length (or order) of the filter, the bandwidth of the fundamental wave and the bandwidth of each subharmonic are selected by DN-PMU fast response performance requirements.
Further, in determining the length or the order of the filter, the filter is required to have a notch effect at an integer multiple frequency of the fundamental wave according to PMU measurement standards and harmonic suppression function of the filter to be designed, and the filter length should be limited to 1/f 0 ～2.5/f 0 Between them.
Bandwidth B of fundamental wave and bandwidth B of each subharmonic q Considering that the q-th harmonic frequency is q times the fundamental frequency, requires B q =q×b. If b=4 Hz is required according to the P-type measurement, then B q ＝4qHz。
Step S104, bringing the cost function, the order of the filter to be optimized, the fundamental wave bandwidth and the bandwidth of each subharmonic into a calculation formula to generate an optimization problem containing constraint.
Specifically, the optimization problem containing constraints is defined as follows:
wherein α= (α) 1 ,L,α M/2 ) M is the filter order, W p Weight coefficient for differential passband performance, W h The harmonic resistance is provided with a performance weight coefficient, W n Weight coefficient omega for full-band anti-noise performance p Normalized bandwidth for p-th harmonic, alpha k Is the independent variable of the objective function, k is the sum coefficient omega 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s For sampling frequency of synchronous phasor measurement unit of power distribution network, delta omega q ＝2πB q /f s Normalized bandwidth for q-th harmonic, B q Is the q-th harmonic bandwidth.
Step S105, solving the optimization problem containing the constraint, and optimizing the filter to be optimized according to the solving result.
The solving process is as follows:
definition of the definition
Wherein lambda is Lagrange eigenvalue, alpha k An argument for an objective function;
order theThe final set of equations is:
wherein the method comprises the steps of
Solving the linear equation set to obtain alpha= (alpha) 1 ,L,α M/2 ) The system function expression of the FIR low-pass digital differential filter is obtained by the following steps:
the embodiment of the invention provides a design method of a low-pass digital differential filter for DN-PMU frequency measurement, which can overcome the influence of factors such as harmonic waves, noise, frequency fluctuation and the like on frequency measurement and realize quick and accurate measurement of the frequency of a power distribution network under the data window length required by P-type (quick response type) PMUs.
In the above step, the signal sampling frequency f is set s =2.4 kHz, grid standard frequency f 0 =50 Hz, fundamental bandwidth b=4hz, q-th harmonic bandwidth B q Q×b=4 qHz, filter order m=70 (filter length 1.48 cycles), weighting coefficients W respectively p ＝1000,W h =100 and W n The filter coefficients of the designed FIR low-pass digital differential filter are shown in fig. 2, and the amplitude-frequency response of the filter is shown in fig. 3.
The embodiment of the invention evaluates the design result by referring to IEEE C37.118.1-2011 and revisions of IEEE C37.118.1a-2014, and compares the design result with the frequency measurement reference algorithm measurement result provided by IEEE C37.118.1-2011 and revisions of IEEE C37.118.1a-2014 appendix C, thereby fully describing the superior performance of the design filter of the method. The embodiment of the present invention employs the FIR low-pass digital differential filter shown in fig. 2, and the frequency measurement is implemented by filtering the single-phase synchronous phasor phase sequence (hereinafter referred to as the algorithm of the present invention, or the single-phase low-pass differential algorithm) assuming that only a single-phase (a-phase) input signal is obtained. The frequency calculation formula of the reference algorithm is IEEE C37.118.1a-2014 (C.3), and frequency measurement is realized by respectively carrying out differential calculation on the phase sequence of the phase A and the phase sequence of the phase of the positive sequence (hereinafter referred to as a single-phase differential algorithm and a three-phase differential algorithm) under the assumption that only single-phase (A phase) signals are obtained and fully symmetrical three-phase signals are obtained. The synchronous phasors processed by the embodiment of the invention and the reference algorithm are measured under the following test conditions by a P-type phasor measurement scheme (see IEEE C37.118.1-2011 figure C.1) provided by an IEEE C37.118.1-2011 annex C, wherein the A-phase sequence of the synchronous phasors obtained by measurement is provided for the embodiment of the invention, and the A-phase sequence of the synchronous phasors obtained by measurement and the positive-sequence synchronous phasor sequence are provided for the reference algorithm.
With reference to IEEE C37.118.1-2011 and its revisions IEEE c37.118.1a-2014, the set of test conditions are shown below, where a) to c) are used to test measurement accuracy under static grid conditions, d) and e) are used to test measurement accuracy under dynamic grid conditions, experiment f) tests the measured fast response performance, statistical maximum response time:
a) Fundamental frequency offset: the power grid signal only contains fundamental waves, the fundamental waves are ideal sine waves, and the frequency deviation range is-2 Hz.
b) Harmonic interference: the power grid signal contains 2, 3, 5, 7, 9 and 11 harmonics in addition to the fundamental wave; the fundamental wave and the harmonic wave are ideal sine waves, the frequency offset range of the fundamental wave is-2 Hz, and the harmonic frequency is integer times corresponding to the fundamental wave frequency; 2. the amplitudes of the 3 rd harmonic and the 5 th harmonic are the same, the amplitudes of the 7 th harmonic, the 9 th harmonic and the 11 th harmonic are the same, the amplitude of the first 3 rd harmonic is 2 times of the amplitude of the last 3 rd harmonic, and the total harmonic distortion is set to be 1% and 10%.
c) Fundamental sine amplitude and phase modulation: the network signal contains only fundamental waves, which are respectively frequency f m Sine wave amplitude modulation and phase modulation, the modulation depth is 0.1, the fundamental wave has no static frequency offset, and the modulation frequency f m Is 0-2 Hz.
d) Fundamental chirp: the grid signal contains only the fundamental wave, whose frequency varies linearly with time (increasing from 48Hz to 52Hz and decreasing from 52Hz to 48 Hz), with a frequency variation rate of 1Hz/s.
e) Fundamental amplitude and phase step transitions: the standard power frequency sine wave generates a + -10% amplitude step jump and a + -10 DEG phase step jump respectively.
The frequency error simulation curves for tests a) to d) under the three frequency measurement modes are given in fig. 4 to 8, respectively, and the maximum values of the frequency measurement errors under the three measurement modes are listed in table 1; the response times of the frequency measurements under test e) are listed in table 2. From the error statistics it can be seen that: 1) The direct application of the single-phase differential algorithm to single-phase frequency measurement can generate very large error, and effective measurement cannot be realized; 2) The single-phase low-pass differential algorithm provided by the invention shows very high measurement precision under various test conditions, and is particularly suitable for the environmental measurement of a power distribution network due to excellent harmonic resistance (obviously superior to a three-phase differential algorithm). From the frequency measurement response times listed in table 2, although the inventive algorithm increases the measurement response time by about 1 power frequency period compared to the reference algorithm, it clearly meets the measurement standard requirements. Table 1 shows the statistical comparison results of the maximum frequency measurement error values of DN-PMU under the sine phase modulation condition and the differential three-phase algorithm and the single-phase differential algorithm under the typical static and dynamic conditions of the power grid. Table 2 shows the statistical comparison result of the frequency measurement response time measured by DN-PMU under the sine phase modulation condition and the differential three-phase algorithm and the single-phase differential algorithm under the fundamental wave amplitude and phase jump condition.
TABLE 1
TABLE 2
According to the optimization method of the FIR filter for realizing frequency measurement by using the DN-PMU, which is provided by the embodiment of the invention, the length of the actual filter is limited due to the quick response requirement of the PMU measurement, and the ideal frequency characteristic can not be realized. According to the signal environment of the power distribution network and DN-PMU measurement characteristics, on the premise of ensuring passband differential characteristics preferentially, harmonic suppression is focused, and then the anti-noise performance is considered. Therefore, the limited data window can be utilized to the maximum extent, various performance indexes are considered, and the rapid and accurate measurement of the frequency is realized.
Next, an optimization device of an FIR filter for realizing frequency measurement by using a DN-PMU according to an embodiment of the present invention will be described with reference to the accompanying drawings.
Fig. 9 is a schematic diagram of an optimization device structure of an FIR filter for implementing frequency measurement by DN-PMU according to an embodiment of the invention.
As shown in fig. 9, the optimization device of the FIR filter for realizing frequency measurement by using the DN-PMU includes: a characterization module 901, an establishment module 902, a parameter selection module 903, a generation module 904 and an optimization module 905.
The characterization module 901 is configured to characterize the differential passband performance, the stopband performance of each subharmonic, and the anti-noise performance of the full frequency band of the filter to be optimized with technical indexes.
A building module 902, configured to build a cost function according to the characterized technical index.
The parameter selection module 903 is configured to determine an order, a fundamental bandwidth, and a bandwidth of each subharmonic of the filter to be optimized according to PMU standards.
The generating module 904 is configured to bring the cost function and the order, the fundamental bandwidth, and the subharmonic bandwidth of the filter to be optimized into a calculation formula to generate an optimization problem including constraints.
And the optimization module 905 is configured to solve an optimization problem including constraints, and optimize the filter to be optimized according to the solution result.
Further, in an embodiment of the present invention, the differential passband performance, the impedance band performance of each sub-harmonic, and the full-band anti-noise performance of the filter to be optimized are respectively represented by technical indexes, including:
wherein delta 1 For differential passband performance of the filter, H (e jω ) For the frequency response characteristic of the filter to be optimized omega 1 Normalized bandwidth for fundamental wave, delta q Omega for each subharmonic stop band performance 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s For the sampling frequency of the synchronous phasor measurement unit of the distribution network, Δω q ＝2πB q /f s Normalized bandwidth for q-th harmonic, B q For the q-order harmonic bandwidth, G n Is the full-band anti-noise performance.
Further, in one embodiment of the present invention, establishing a cost function according to the characterized technical index includes:
wherein W is p Weight coefficient for differential passband performance, W h Is the harmonic stop band performance weighting coefficient, W n Weight coefficient for full-band anti-noise performance, H (e jω ) For the frequency response characteristic of the filter to be optimized omega 1 Normalized bandwidth for fundamental wave, delta q Omega for each subharmonic stop band performance 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s Sampling for synchronous phase measurement units of power distribution networkSample frequency, deltaomega q ＝2πB q /f s Normalized bandwidth for q-th harmonic, B q Is the q-th harmonic bandwidth.
It should be noted that the foregoing explanation of the method embodiment is also applicable to the apparatus of this embodiment, and will not be repeated here.
According to the optimization device of the FIR filter for realizing frequency measurement by using the DN-PMU, which is provided by the embodiment of the invention, the length of the actual filter is limited due to the quick response requirement of the PMU measurement, and the ideal frequency characteristic can not be realized. According to the signal environment of the power distribution network and DN-PMU measurement characteristics, on the premise of ensuring passband differential characteristics preferentially, harmonic suppression is focused, and then the anti-noise performance is considered. Therefore, the limited data window can be utilized to the maximum extent, various performance indexes are considered, and the rapid and accurate measurement of the frequency is realized.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (6)
1. An optimization method of an FIR filter for realizing frequency measurement by DN-PMU is characterized by comprising the following steps:
the differential passband performance, the stop band performance of each subharmonic and the full-band anti-noise performance of the filter to be optimized are respectively represented by technical indexes;
establishing a cost function according to the characterized technical indexes;
determining the order, fundamental wave bandwidth and each subharmonic bandwidth of the filter to be optimized according to PMU standard;
bringing the cost function, the order of the filter to be optimized, the fundamental wave bandwidth and the bandwidth of each subharmonic into a calculation formula to generate an optimization problem containing constraint;
solving the optimization problem containing the constraint, and optimizing the filter to be optimized according to a solving result;
the step of establishing the cost function according to the characterized technical indexes comprises the following steps:
wherein W is p Weight coefficient for differential passband performance, W h Is the harmonic stop band performance weighting coefficient, W n Weight coefficient for full band anti-noise performance, H (e jω ) For the frequency response of the filter to be optimized, Δω 1 Normalized bandwidth for fundamental wave omega 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s For sampling frequency of synchronous phasor measurement unit of power distribution network, delta omega q ＝2πB q /f s Normalized band for q-th harmonicWidth B q The q-th harmonic bandwidth;
the optimization problem including constraint is:
wherein α= (α) 1 ,L,α M/2 ) M is the filter order, ω p Normalized frequency, alpha, of the p-th harmonic k K is a sum coefficient, which is an argument of the objective function.
2. The method of claim 1, wherein characterizing the differential passband performance, the subharmonic stopband performance, and the full band anti-noise performance of the filter to be optimized with the respective specifications comprises:
wherein delta 1 Delta for differential passband performance of filter q G for each subharmonic stop band performance n Is the full-band anti-noise performance.
3. The method of claim 1, wherein determining the order of the filter to be optimized based on PMU criteria comprises: according to PMU measurement standard and harmonic suppression function filter of the filter to be optimized, the filter to be optimized has notch effect at integral multiple frequency of fundamental wave, and the length of the filter to be optimized is 1/f 0 ～2.5/f 0 Between, where f 0 ＝50Hz。
4. The method of claim 1, wherein determining the fundamental bandwidth and the respective subharmonic bandwidths based on PMU standards comprises: the q-order harmonic frequency is q times of the fundamental wave frequency, requiring B q ＝q×B，B q The q-th harmonic bandwidth and B the fundamental bandwidth.
5. An optimization device of an FIR filter for realizing frequency measurement by using a DN-PMU, comprising:
the characterization module is used for respectively characterizing the differential passband performance, the stop band performance of each subharmonic and the full-band anti-noise performance of the filter to be optimized by using technical indexes;
the establishing module is used for establishing a cost function according to the characterized technical indexes;
the parameter selection module is used for determining the order, the fundamental wave bandwidth and each subharmonic bandwidth of the filter to be optimized according to PMU standards;
the generating module is used for bringing the cost function, the order, the fundamental wave bandwidth and the subharmonic bandwidth of the filter to be optimized into a calculation formula to generate an optimization problem containing constraint;
the optimization module is used for solving the optimization problem containing the constraint and optimizing the filter to be optimized according to the solving result;
the step of establishing the cost function according to the characterized technical indexes comprises the following steps:
wherein W is p Weight coefficient for differential passband performance, W h Is the harmonic stop band performance weighting coefficient, W n Weight coefficient for full band anti-noise performance, H (e jω ) For the frequency response of the filter to be optimized, Δω 1 Normalized bandwidth for fundamental wave omega 0 ＝2πf 0 /f s Normalized frequency of fundamental wave, f 0 ＝50Hz，f s For sampling frequency of synchronous phasor measurement unit of power distribution network, delta omega q ＝2πB q /f s Normalized bandwidth for q-th harmonic, B q The q-th harmonic bandwidth;
the optimization problem including constraint is:
wherein α= (α) 1 ,L,α M/2 ) M is the filter order, ω p Normalized frequency, alpha, of the p-th harmonic k K is a sum coefficient, which is an argument of the objective function.
6. The apparatus of claim 5, wherein the characterizing the differential passband performance, the subharmonic stopband performance, and the full band anti-noise performance of the filter to be optimized with the respective specifications comprises:
wherein delta 1 Delta for differential passband performance of filter q G for each subharmonic stop band performance n Is the full-band anti-noise performance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110212367.XA CN113162044B (en) | 2021-02-25 | 2021-02-25 | Optimization method and device for frequency measurement of frequency-dependent impulse response (FIR) filter by digital subscriber unit (DN-PMU) |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110212367.XA CN113162044B (en) | 2021-02-25 | 2021-02-25 | Optimization method and device for frequency measurement of frequency-dependent impulse response (FIR) filter by digital subscriber unit (DN-PMU) |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113162044A CN113162044A (en) | 2021-07-23 |
| CN113162044B true CN113162044B (en) | 2023-09-01 |
Family
ID=76883503
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110212367.XA Active CN113162044B (en) | 2021-02-25 | 2021-02-25 | Optimization method and device for frequency measurement of frequency-dependent impulse response (FIR) filter by digital subscriber unit (DN-PMU) |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113162044B (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107104741A (en) * | 2017-05-02 | 2017-08-29 | 浙江金之路信息科技有限公司 | A kind of index coefficient of low time delay digital filter determines method |
| CN109444519A (en) * | 2018-10-30 | 2019-03-08 | 国网上海市电力公司 | Substation's noise source separation method towards complicated acoustic environment |
| CN110389312A (en) * | 2019-07-17 | 2019-10-29 | 华北电力大学 | A kind of calibrator phasor measurement method being applicable in PMU test on site |
| US10884038B1 (en) * | 2020-06-08 | 2021-01-05 | North China Electric Power University | Phasor estimation algorithm for PMU calibration |
| CN112305310A (en) * | 2020-10-19 | 2021-02-02 | 华北电力大学 | Synchronous phasor measurement method suitable for different application scenes |
-
2021
- 2021-02-25 CN CN202110212367.XA patent/CN113162044B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107104741A (en) * | 2017-05-02 | 2017-08-29 | 浙江金之路信息科技有限公司 | A kind of index coefficient of low time delay digital filter determines method |
| CN109444519A (en) * | 2018-10-30 | 2019-03-08 | 国网上海市电力公司 | Substation's noise source separation method towards complicated acoustic environment |
| CN110389312A (en) * | 2019-07-17 | 2019-10-29 | 华北电力大学 | A kind of calibrator phasor measurement method being applicable in PMU test on site |
| US10884038B1 (en) * | 2020-06-08 | 2021-01-05 | North China Electric Power University | Phasor estimation algorithm for PMU calibration |
| CN112305310A (en) * | 2020-10-19 | 2021-02-02 | 华北电力大学 | Synchronous phasor measurement method suitable for different application scenes |
Non-Patent Citations (1)
| Title |
|---|
| 脉冲噪声干扰下同步相量测量;汪芙平等;《中国电机工程学报》;20200305;第40卷(第5期);第1673-1682、S26页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113162044A (en) | 2021-07-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Kamwa et al. | Adaptive phasor and frequency-tracking schemes for wide-area protection and control | |
| Asiminoaei et al. | A digital controlled PV-inverter with grid impedance estimation for ENS detection | |
| CN110231514B (en) | Synchronous phasor measurement method suitable for broadband measurement | |
| CN107345984B (en) | A kind of adaptive synchronicity phasor measurement method based on signal identification | |
| CN103401238B (en) | A kind of power load modelling approach based on Measurement-based approach | |
| CN103983847B (en) | Based on the adaptive frequency track measuring method of RLS in a kind of synchronous phasor measurement | |
| CN109490630B (en) | Dynamic phasor measurement method based on matrix beam | |
| CN112865181B (en) | Photovoltaic inverter parameter identification method and device based on port impedance characteristics | |
| Ikken et al. | PLL synchronization method based on second-order generalized integrator for single phase grid connected inverters systems during grid abnormalities | |
| CN103515955A (en) | Deadbeat power control method for grid-side converter under network voltage unbalance | |
| CN112213560A (en) | High-precision power grid broadband signal measuring method based on Z-ADALINE | |
| Zhang et al. | Shifting window average method for phasor measurement at offnominal frequencies | |
| CN108414838B (en) | Method for measuring line impedance of inverter parallel system | |
| CN112511056A (en) | Robust generator dynamic state estimation method based on phasor measurement | |
| Novanda et al. | Assessment of frequency and harmonic distortions during wind farm rejection test | |
| CN109145825A (en) | A kind of coherent noise filtering method and system | |
| CN104007408A (en) | Method and device for on-line detection of dynamic performance of PMU | |
| CN113162044B (en) | Optimization method and device for frequency measurement of frequency-dependent impulse response (FIR) filter by digital subscriber unit (DN-PMU) | |
| CN207472983U (en) | A kind of electric network impedance on-line identification device based on PRBS disturbance injections | |
| Fang et al. | Response time of reactive power based on different definitions and algorithms | |
| Kušljević et al. | Active power measurement algorithm for power system signals under non-sinusoidal conditions and wide-range frequency deviations | |
| Adžić et al. | Improved pll for power generation systems operating under real grid conditions | |
| Begovic et al. | Issues related to the implementation of synchrophasor measurements | |
| Kunac et al. | Grid Voltage Amplitude and Frequency Real-Time Estimation using Linear Kalman Filter | |
| CN112688321B (en) | Large power grid subsynchronous oscillation path acquisition method and system |
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 |