CN103630748B  A kind of device and method measured for microgrid harmonic impedance  Google Patents
A kind of device and method measured for microgrid harmonic impedance Download PDFInfo
 Publication number
 CN103630748B CN103630748B CN201310562344.7A CN201310562344A CN103630748B CN 103630748 B CN103630748 B CN 103630748B CN 201310562344 A CN201310562344 A CN 201310562344A CN 103630748 B CN103630748 B CN 103630748B
 Authority
 CN
 China
 Prior art keywords
 harmonic
 circuit
 voltage
 signal
 micro
 Prior art date
Links
 244000171263 Ribes grossularia Species 0.000 claims abstract description 90
 238000002347 injection Methods 0.000 claims abstract description 28
 239000007924 injections Substances 0.000 claims abstract description 28
 238000000034 methods Methods 0.000 claims abstract description 8
 238000005070 sampling Methods 0.000 claims abstract description 8
 230000003321 amplification Effects 0.000 claims description 25
 238000003199 nucleic acid amplification method Methods 0.000 claims description 25
 235000019800 disodium phosphate Nutrition 0.000 claims description 13
 230000003750 conditioning Effects 0.000 claims description 8
 238000001914 filtration Methods 0.000 claims description 8
 238000006243 chemical reactions Methods 0.000 claims description 5
 238000002847 impedance measurement Methods 0.000 abstract description 8
 239000011159 matrix materials Substances 0.000 description 12
 238000010586 diagrams Methods 0.000 description 9
 238000004458 analytical methods Methods 0.000 description 8
 230000002159 abnormal effects Effects 0.000 description 2
 239000003990 capacitor Substances 0.000 description 2
 230000000875 corresponding Effects 0.000 description 2
 280000139470 Prime Power companies 0.000 description 1
 230000015572 biosynthetic process Effects 0.000 description 1
 238000004364 calculation methods Methods 0.000 description 1
 230000000694 effects Effects 0.000 description 1
 238000005516 engineering processes Methods 0.000 description 1
 238000005755 formation reactions Methods 0.000 description 1
 238000005259 measurements Methods 0.000 description 1
 239000000203 mixtures Substances 0.000 description 1
 230000000051 modifying Effects 0.000 description 1
 230000001105 regulatory Effects 0.000 description 1
 238000001228 spectrum Methods 0.000 description 1
 230000001360 synchronised Effects 0.000 description 1
Abstract
Description
[technical field]
The present invention relates to micro power network field, particularly a kind of device and method measured for microgrid harmonic impedance.
[background technology]
Micro power network contains multiple distributed power source, and distributed power source is accessed in micro power network by converters mostly.Reciprocation between converters and the reciprocation between converters and electrical network can reduce the stability of micro power network system greatly.Therefore, the stability of system must be considered in the design and working of micro power network.And the stability of system and the harmonic impedance parameter of system have close relationship, stability analyze of method to system adopting harmonic impedance parameter identification is current study hotspot, and therefore the Measurement accuracy of microgrid harmonic impedance just seems particularly important.
The main method that current system impedance is measured has switched capacitor method, thyristor branch road switching method and harmonic current injection etc.Switched capacitor method is reduced investment outlay, but the harmonic wave that this method produces is uncontrollable, fractional harmonic electric current may be caused to lack, and amplitude is too small, and radiofrequency component decay is very large; Thyristor branch road switching method can control the size of harmonic electric current, but accurately can not control the harmonic frequency of injected system, and signal HFS lacks; Two kinds of abovementioned methods all can not the harmonic impedance of Measurement accuracy micro power network.
Harmonic current injection then utilizes harmonic current source to inject a controlled harmonic current directly to system, thus can obtain comparatively accurately, system harmonic impedance that frequency spectrum is complete.
Traditional harmonic current source generally adopts the mode of PWM, is both regulated the characteristic of harmonic electric current by the breakmake of gauge tap pipe.But the method is subject to the impact of switching tube switching frequency, the harmonic current of injection is generally at below 1KHz.In some specifically research, harmonic impedance as threephase alternating current system needs the harmonic impedance matrix of measuring system under dq coordinate system, now in measuring, often need to inject one by multiple signal madulation sophisticated signal together to system, now PWM often can not meet the demands.
Therefore how to inject a high frequency in electrical network and the harmonic current signal that can also control easily such as its phase place, amplitude, waveform, how the network after harmonic is carried out to the detection of harmonic voltage, harmonic current, the how harmonic impedance of computational grid each several part, and for the stability analysis etc. of system, be the key issue of research.
[summary of the invention]
The object of the present invention is to provide a kind of device and method measured for microgrid harmonic impedance, all controlled harmonic current of phase place, frequency, amplitude, waveform can be injected to electrical network, with the harmonic impedance of Measurement accuracy micro power network more accurately.
To achieve these goals, the present invention adopts following technical scheme:
For the device that microgrid harmonic impedance is measured, comprise harmonic current source injection device, harmonic voltage and Harmonic currents detection device, data collector, host computer;
Harmonic current source injection device comprises testing circuit, signal generating circuit, amplifying circuit and interface circuit; Testing circuit, for detection of grid voltage signal and after filtering after input signal circuit for generating; Signal generating circuit comprises DSP, D/A converting circuit and FPGA; The output terminal of the input end connection detection circuit of DSP, the voltage signal of DSP to input carries out the phaselocked phase information obtaining voltage signal, then harmonic voltage waveform, harmonic voltage frequency, harmonic voltage amplitude and harmonic voltage waveform phase difference is synthesized with the phase information of voltage signal, generate harmonic voltage signal and export to FPGA; FPGA exports amplifying circuit to after harmonic voltage signal being exported to D/A converting circuit conversion; Amplifying circuit comprises amplitude amplifying circuit and power amplification circuit; The amplitude of harmonic voltage signal that amplitude amplifying circuit logarithmic mode changeover circuit exports exports power amplification circuit to after amplifying; Power amplification circuit exports to interface circuit to after the power amplification of the harmonic voltage signal of input; Interface circuit, the harmonic voltage signal for being exported by power amplification circuit converts harmonic current signal injection to in electrical network;
Harmonic voltage and harmonic current detection circuit, for detecting micro power network before and after harmonic current injection, the harmonic voltage size in network and harmonic current size;
Data collector, samples for the signal detected harmonic voltage and harmonic current detection circuit, and data is fed through host computer;
Host computer, calculating harmonic voltage and harmonic current variable quantity for carrying out process to the signal of sampling, calculating the harmonic impedance of micro power network each several part.
The present invention further improves and is: described testing circuit comprises voltage hall sensor and sample circuit, voltage hall sensor is used for the singlephase or ployphase voltages signal of detection of grid, and the voltage signal that sample circuit is used for voltage hall sensor detects carries out filtering.
The present invention further improves and is: FPGA is for judging that the harmonic voltage signal inputted is whether within default value limited field.
The present invention further improves and is: described signal generating circuit also comprises signal conditioning circuit, is transferred to FPGA carries out protection judgement after the harmonic current signal that the harmonic voltage signal that the temperature signal of the power amplification circuit of collection, power amplification circuit export by described signal conditioning circuit, interface circuit export carries out filtering by DSP.
The present invention further improves and is: described DSP is DSP2812.
For the method that microgrid harmonic impedance is measured, comprise the following steps: adopt and be used for the device that microgrid harmonic impedance measures and inject twice separate harmonic current to micro power network; Detect micro power network before and after twice harmonic current injection by harmonic voltage and Harmonic currents detection device, the harmonic voltage size in network and harmonic current size are also uploaded to host computer by data collecting card; Before and after twice harmonic current injection that host computer is uploaded according to data collecting card, the harmonic voltage size in network and harmonic current size calculate the harmonic impedance of micro power network each several part.
The present invention further improves and is: before and after twice harmonic current injection, and the two groups of harmonic voltages produced in network and current disturbing signal are respectively with
Harmonic impedance matrix in micro power network dq coordinate system is:
Wherein
Relative to prior art, the present invention has following beneficial effect: harmonic current injection device of the present invention to injecting all controllable harmonic current of amplitude, frequency, phase place, waveform in electrical network, thus can improve the precision of network harmonic impedance measurement; Apparatus of the present invention control simple and reliable, and precision is high, and cost is low, to be applicable in low voltage electric network that harmonic impedance is measured, the engineer applied occasion such as design of filter and stability analysis.The inventive method injects independently twice phase place, amplitude, all controllable harmonic current of frequency by harmonic current injection device to electrical network, and adopt the harmonic current of each several part and the harmonic voltage of correspondence thereof in wide band voltage, current Hall sensor Sampling network, after data collector sampling, be fed through the calculating carrying out harmonic impedance in host computer; The inventive method is simple, accuracy is high.
[accompanying drawing explanation]
Fig. 1 micro power network structural representation;
The structured flowchart that Fig. 2 (a) is apparatus of the present invention; The hardware schematic diagram that Fig. 2 (b) is signal generating circuit;
Fig. 3 (a) is the hardwareinitiated process flow diagram of signal generating circuit; The process flow diagram that Fig. 3 (b) occurs for harmonic signal;
Fig. 4 is harmonic impedance calculation flow chart;
Fig. 5 is the threephase alternating current system schematic of equivalence;
Fig. 6 is threephase alternating current system smallsignal model schematic diagram;
Fig. 7 (a) is inverter output impedance selfimpedance measurement result schematic diagram; Fig. 7 (b) is inverter output impedance transimpedance measurement result schematic diagram;
Fig. 8 (a) is load harmonic impedance selfimpedance measurement result schematic diagram; Fig. 8 (b) is load harmonic impedance transimpedance measurement result schematic diagram;
Fig. 9 is stability analysis result schematic diagram.
[embodiment]
As shown in Figure 1, the multiple distributed power source such as photovoltaic generating system, wind power system of having guaranteed replacement in micro power network, in order to the harmonic impedance of measuring system, a kind of device for microgrid harmonic impedance measurement proposed in the present invention as shown in Figure 2.
Refer to shown in Fig. 2 (a) to 3 (b), a kind of device measured for microgrid harmonic impedance of the present invention, comprises harmonic current source injection device, harmonic voltage and Harmonic currents detection device, data collector, host computer.
Harmonic current source injection device is made up of testing circuit, signal generating circuit, amplifying circuit, interface circuit.The core of signal generating circuit is DSP2812 control circuit, and it is by the line voltage of sampling, can be controlled the phase place of output signal, meanwhile, can also be controlled the key element such as amplitude, frequency outputed signal by programming easily by soft phaselocked method.The synthetic schemes of soft phaselocked and harmonic signal is as shown in Fig. 3 (a) He Fig. 3 (b).
Testing circuit is made up of voltage hall sensor and sample circuit, and voltage hall sensor is used for threephase voltage signal Ua, Ub, Uc of detection of grid; Voltage hall sensor connects sample circuit, electrical network threephase voltage signal Ua, Ub, Uc that voltage hall sensor detects in real time deliver in signal generating circuit after the analog to digital conversion and conditioning (filtering) of oversampling circuit, are used for calculating amplitude, the phase place of line voltage.
The hardware of signal generating circuit is take DSP2812 as the control circuit of core, and it also comprises signal conditioning circuit, D/A converting circuit, power module and FPGA.
The input end of DSP2812 receives the threephase voltage signal U of the micro power network gathered _{a}, U _{b}, U _{c}, DSP2812 is to the threephase voltage signal U of input _{a}, U _{b}, U _{c}carry out software phlase locking and obtain threephase voltage signal U _{a}, U _{b}, U _{c}phase information, then by the instruction of harmonic voltage waveform, harmonic voltage frequency instruction, the instruction of harmonic voltage amplitude and the instruction and threephase voltage signal U of harmonic voltage waveform phase difference _{a}, U _{b}, U _{c}phase information synthesize, the harmonic voltage signal generating phase place, frequency, amplitude, waveform controlled exports to FPGA; FPGA is for judging whether the harmonic voltage signal inputted (prevents from damaging followup modulate circuit, power amplifier and interface circuit), if by this harmonic voltage signal U within limited field within limited field _{p}amplifying circuit is exported to after exporting D/A converting circuit conversion to.
Amplifying circuit comprises amplitude amplifying circuit and power amplification circuit, adopts the mode of Linear Amplifer, by harmonic voltage signal U _{p}carry out amplitude amplification and power amplification, in order to make the signal after amplification undistorted, amplifying circuit has the bandwidth of 1MHz, and wherein harmonic distortion is less than 0.01, and signal to noise ratio (S/N ratio) is greater than 95dB, fully meets the requirement of amplification.The harmonic voltage signal U that amplitude amplifying circuit exports DSP _{p}amplitude amplify after export power amplification circuit to; Power amplification circuit is to the harmonic voltage signal U of input _{p}interface circuit is exported to after the power amplification of `.
Harmonic current injection interface circuit, primarily of voltagecurrent converter circuit composition, by the harmonic voltage signal U that prime power amplification circuit exports _{p}`` converts harmonic current signal i to _{p}be injected in electrical network.
Adopt DSP control circuit and power amplification circuit to produce the method for harmonic signal, avoid the restriction of conventional P WM method breaker in middle pipe switching frequency, more required harmonic signals can be produced.
Signal generating circuit also comprises signal conditioning circuit, and the input end of signal conditioning circuit connects temperature signal, the harmonic voltage signal U of power amplification circuit _{p}``, harmonic current signal i _{p}, and be transferred to FPGA by DSP after filtering is carried out to these signals and judge, judge that whether these signals are abnormal, send corresponding alarm signal if abnormal.
Harmonic voltage and harmonic current detection circuit are made up of Hall element, detect micro power network before and after harmonic current injection, the harmonic voltage size in network and harmonic current size.
Data collector, adopts highspeed data acquisition card, samples, and data are fed through host computer to the signal that Hall element detects.
The signal of host computer to sampling processes, and calculates harmonic voltage and harmonic current variable quantity, calculates the harmonic impedance of micro power network each several part.
The measuring method flow process of system harmonic impedance parameter:
In threephase alternating current system, for threephase symmetrical system, its dq coordinate system medium frequency is ω _{h}current disturbing and its corresponding voltage disturbance between relation can be designated as:
For two groups of separate voltage and current disturbing signals with then have:
Wherein
Thus the harmonic impedance matrix that can obtain in dq coordinate system is now:
As can be seen from the above equation, in order to obtain the harmonic impedance of system at a certain Frequency point, needing to inject at this frequency place twice separate harmonic current, namely must ensure that the square formation that two groups of current disturbing signals form is nonsingular matrix.
To the flow process of system harmonic electric current and data collection and analysis as shown in Figure 4.
As can be seen from Figure 4, the separate harmonic current of two groups of injection needs to carry out dq conversion and fft analysis respectively, then substitutes in impedance matrix and solves impedance parameter.
The stability analysis of micro power network system:
By the power module in micro power network integrally, integrally, then system can be equivalent to a threephase alternating current system as shown in Figure 5 to loading section, if mains side be input as u _{s}, its voltage gain transport function is G _{s}, the output of loadside is u _{o}, voltage gain transport function is G _{l}.
In synchronous rotating frame, modeling is carried out to this threephase alternating current system, its smallsignal model can be obtained as shown in Figure 6, wherein for the smallsignal disturbance of power input voltage, with be respectively busbar voltage and load output voltage to the response of this smallsignal disturbance.Z _{s}(s) and Y _{l}s () is respectively mains side equivalent output impedance matrix and loadside equivalent inpnt admittance matrix.
Load output voltage response can be obtained by Fig. 6 to be shown below with the transport function relation between power input voltage disturbance:
Due to voltage gain transport function G _{sdq}(s) and G _{ldq}s generally there is not RHP limit in (), therefore the stability of system depends on back rate matrix L (s)=Z _{s}(s) Y _{l}(s).
When power subsystem and load subsystem independent operating are stablized, i.e. mains side equivalent output impedance matrix Z _{s}(s) and loadside equivalent inpnt admittance matrix Y _{l}when () does not all exist RHP limit s, two of L (s) characteristic locuses are limited in the stability that can ensure system in s planar unit circle.The eigenwert of matrix when point on characteristic locus represents a certain frequency, therefore, when all eigenwerts of L (s) are all within unit circle, AC system is stablized.
λ _{i}(jω)<1∞<ω<∞,i＝1,2
Adopt above impedance measurement method, to the harmonic impedance measurement result of system as shown in Fig. 7 ~ Fig. 8, wherein comparatively smooth curve is theoretical value, and another curve is experimental measurements.Wherein Fig. 7 (a) output impedance selfimpedance Z under dq coordinate system that is source inventer in micro power network _{dd}measurement result, Fig. 7 (b) is inverter output impedance transimpedance Z _{dq}measurement result.Fig. 8 (a) load selfimpedance Z _{dd}measurement result, as can be seen from the figure, measured value and the theoretical value of harmonic impedance are consistent, demonstrate the validity of measurement mechanism.Host computer to the result of system stability analysis as shown in Figure 9, as can be seen from the figure return the eigenvalue of rate matrix all within unit circle, now stablize by system.
The present invention gives a kind of device and method measured for microgrid harmonic impedance, and built experiment porch and verify, as can be seen from experimental waveform, harmonic current injection device to injecting all controllable harmonic current of amplitude, frequency, phase place, waveform in electrical network, can meet above requirement; The present invention can measure each several part harmonic impedance of micro power network accurately, and can analyze the stability of system accurately.Compared to other scheme, it controls reliable, and precision is high, and cost is low, is applicable to the engineer applied occasions such as the impedance measurement of low pressure micro power network and stability analysis.
Claims (6)
Priority Applications (1)
Application Number  Priority Date  Filing Date  Title 

CN201310562344.7A CN103630748B (en)  20131111  20131111  A kind of device and method measured for microgrid harmonic impedance 
Applications Claiming Priority (1)
Application Number  Priority Date  Filing Date  Title 

CN201310562344.7A CN103630748B (en)  20131111  20131111  A kind of device and method measured for microgrid harmonic impedance 
Publications (2)
Publication Number  Publication Date 

CN103630748A CN103630748A (en)  20140312 
CN103630748B true CN103630748B (en)  20160330 
Family
ID=50212004
Family Applications (1)
Application Number  Title  Priority Date  Filing Date 

CN201310562344.7A CN103630748B (en)  20131111  20131111  A kind of device and method measured for microgrid harmonic impedance 
Country Status (1)
Country  Link 

CN (1)  CN103630748B (en) 
Families Citing this family (8)
Publication number  Priority date  Publication date  Assignee  Title 

CN104269850B (en) *  20140730  20160817  西安交通大学  A kind of control method of the active harmonics resistance being applied to shnt capacitor 
CN104898019A (en) *  20150511  20150909  国家电网公司  Harmonic source positioning and harmonic responsibility division method applied to active distribution network 
CN106329563B (en)  20150628  20190528  华为技术有限公司  A kind of method and inverter of the inspection of gridconnected inverters stability 
CN105717360A (en) *  20160126  20160629  云南电网有限责任公司电力科学研究院  Lowvoltage singlephase harmonic impedance measuring method and device 
CN106908665B (en) *  20170210  20190329  西南交通大学  A kind of onephase ACsystem dq decomposition impedance measurement method 
CN107064646B (en) *  20170523  20200221  广西大学  Power grid impedance realtime identification method for multiinput multioutput asymmetric system 
CN109038534A (en) *  20180717  20181218  中国南方电网有限责任公司  A kind of novel DC transmission system harmonic impedance scanning means 
CN111175578A (en) *  20200116  20200519  武汉大学  Impedance detection system and method for singlephase or threephase inverter gridconnected system under complex working condition 
Citations (3)
Publication number  Priority date  Publication date  Assignee  Title 

CN101706532A (en) *  20091125  20100512  国网电力科学研究院武汉南瑞有限责任公司  Method and device for measuring harmonic impedance 
CN102749521A (en) *  20120718  20121024  华北电力大学（保定）  Method for computing harmonic impedance of power system 
CN102914697A (en) *  20121030  20130206  西安交通大学  Microgrid harmonic impedance measuring method based on threephase symmetrical square wave current injection 
Family Cites Families (2)
Publication number  Priority date  Publication date  Assignee  Title 

EP2220767B1 (en) *  20070913  20130904  Microchip Technology Germany II GmbH & Co. KG  Method and circuit for detecting an approach to an electrode device 
CN102499678B (en) *  20110923  20131106  中国人民解放军第四军医大学  Impedance measuring device and measuring method of portable impedance imaging system 

2013
 20131111 CN CN201310562344.7A patent/CN103630748B/en active IP Right Grant
Patent Citations (3)
Publication number  Priority date  Publication date  Assignee  Title 

CN101706532A (en) *  20091125  20100512  国网电力科学研究院武汉南瑞有限责任公司  Method and device for measuring harmonic impedance 
CN102749521A (en) *  20120718  20121024  华北电力大学（保定）  Method for computing harmonic impedance of power system 
CN102914697A (en) *  20121030  20130206  西安交通大学  Microgrid harmonic impedance measuring method based on threephase symmetrical square wave current injection 
NonPatent Citations (1)
Title 

电力系统谐波阻抗特性及测量方法的探讨;王彦东等;《电工技术杂志》;20041231(第3期);6467 * 
Also Published As
Publication number  Publication date 

CN103630748A (en)  20140312 
Similar Documents
Publication  Publication Date  Title 

de Souza et al.  A method for extracting the fundamentalfrequency positivesequence voltage vector based on simple mathematical transformations  
Ciobotaru et al.  Online grid impedance estimation based on harmonic injection for gridconnected PV inverter  
CN103545838B (en)  A kind of combining inverter mixing damping adaptive control method be applicable under light current net access conditions  
CN103487652B (en)  Frequency selfadaptive realtime fractional harmonic wave detection method  
CN102664413B (en)  Method for controlling harmonic current of fullpower converter for suppressing wind power grid integration and controller  
CN105071405A (en)  Microgrid system with asymmetric nonlinear load and power balancing control method  
CN106526328B (en)  It is a kind of suitable for the generalized impedance of power grid and networked devices measurement and calculation method  
CN101459334A (en)  Electrical power system failure information obtaining method  
CN105259414B (en)  A kind of electric network impedance online test method based on inverter  
CN103515955B (en)  Grid side converter dead beat Poewr control method under unbalanced source voltage  
CN101055299A (en)  Impact load electric energy metering method  
CN204882843U (en)  Transformer remanence detects and demagnetization device  
CN103558436A (en)  Method for network voltage amplitude, frequency and phase angle detection based on onephase phaselocked loop algorithm  
CN101793918A (en)  Voltage sag detection method  
CN102832620A (en)  System and method for harmonic detection and control of APF (active power filter) based on windowed allphase FFT (fast Fourier transform)  
CN103376363B (en)  Impedance measurement method of threephase alternating current system  
CN204758716U (en)  Dc to ac converter is at ring testing arrangement  
CN103199791B (en)  Threephase current reconstruction method using single sampling resistance  
TWI227325B (en)  Display device of electric power saving effect using for inverter apparatus  
CN102590618B (en)  Detection method of positive sequence voltage phase of fundamental wave for power grid  
Knop et al.  High frequency grid impedance analysis by current injection  
CN101907697B (en)  Dynamic property tester of electric energy meter  
CN103344368A (en)  Squirrelcage type asynchronous motor energy efficiency online monitoring method based on measurable electrical amount  
CN101706532B (en)  Method and device for measuring harmonic impedance  
CN101726656B (en)  Harmonic current detection and filtration method and device of active power filter 
Legal Events
Date  Code  Title  Description 

PB01  Publication  
C10  Entry into substantive examination  
SE01  Entry into force of request for substantive examination  
C14  Grant of patent or utility model  
GR01  Patent grant 