CN101814718A - Microcomputer-based differential protection method of frequency-conversion and speed-regulation motor - Google Patents
Microcomputer-based differential protection method of frequency-conversion and speed-regulation motor Download PDFInfo
- Publication number
- CN101814718A CN101814718A CN 201010146226 CN201010146226A CN101814718A CN 101814718 A CN101814718 A CN 101814718A CN 201010146226 CN201010146226 CN 201010146226 CN 201010146226 A CN201010146226 A CN 201010146226A CN 101814718 A CN101814718 A CN 101814718A
- Authority
- CN
- China
- Prior art keywords
- frequency
- differential protection
- microcomputer
- current
- speed
- 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.)
- Granted
Links
Images
Landscapes
- Control Of Ac Motors In General (AREA)
Abstract
The invention discloses a microcomputer-based differential protection method of a frequency-conversion and speed-regulation motor, comprising the following steps of: (1) respectively sampling inflow current and outflow current of a controlled motor; (2) directly comparing the size of an inflow current sampling value with an outflow current sampling value at a time; (3) calculating the proportion between the comparison value number which satisfies fault conditions and the comparison value number which does not satisfy the fault conditions at a time interval; and (4) and sending a protection action signal when the proportion is greater than a setting numerical value. The microcomputer-based differential protection method just needs to compare the size relationship of each sampling point without calculating the effective value of the current, thereby being unnecessary to carry out Fourier calculation. The method has less calculation amount and fast response speed, overcomes the defects of the prior art as the Fourier calculation is not needed and can adapt to the differential protection of the frequency-conversion and speed-regulation motor.
Description
[technical field]
The present invention relates to the motor differential protecting technology, relate in particular to a kind of microcomputer-based differential protection method of frequency-conversion and speed-regulation motor.
[background technology]
Since differential protection have be swift in motion, highly sensitive and install characteristics such as simple, in high capacity motor, obtained using widely." thermal power plant station service designing technique regulation " requirement, 2Mw and above motor should be installed differential protection.Have the motor of branch phase terminal for the following neutral point of 2Mw, when the current quick sensitivity is not enough, also should install differential protection.
Differential protection constitutes by means of the difference of protected element current amplitude, phase place when the internal fault traditionally, i.e. the principle of top and end current numerical values recited and phase place formation relatively.
Tradition microcomputer type motor differential protection all is based on the phasor differential principle; promptly utilize the discrete fourier algorithm to calculate real, the imaginary part of electric current according to a cycle sampled point; calculate the amplitude and the phase place of differential current and stalling current again, by relatively constituting operating criterion.Yet internal microcomputer type differential protection designs according to industry standard Microcomputer Protection general technical specifications at present.The rated frequency of general technical specifications regulation is 50Hz.The Digital Signal Processing of microcomputer-based differential protection device is based on Fourier transform; Fourier transform has a fundamental frequency; can only the computes integer order harmonic components; microcomputer protecting device is provided with low pass filter; the fundamental frequency following range of Fourier transform is 45～55Hz; much smaller than the frequency converter frequency transformation range, so conventional microcomputer-based differential protection is not suitable for the frequency conversion loop.
For adapting to frequency change, can pass through following method improvement, but all be difficult to satisfy the demand fully:
(1) keep sample rate constant, this moment, the ripple sampling number changed with frequency shift weekly.This scheme then needs the Fourier coefficient of real-time calculating sampling point, and Fourier coefficient is calculated as the surmount function computing, and amount of calculation is bigger, so this method is difficult to realize.
(2) keep that the ripple sampling number is constant weekly, need real-time frequency measurement to adjust sample rate this moment.The advantage of this method is to carry out Fourier when calculating, and the coefficient of each sampled point is fixed, and amount of calculation is less.The pass of sampling number N and sample rate S, system frequency F is: N=S/F, and the microcomputer-based differential protection device generally is equipped with low pass filter, knows S＞2F1 by sampling thheorem, F1 is a low pass filter cutoff frequency.But when the frequency converter running frequency is very little, know that by S＞2F1 low pass filter cutoff frequency is very low, frequency be higher than cut-off frequency all by elimination, sample magnitude reduces greatly, has a strong impact on certainty of measurement.
Comprehensive above reason, traditional microcomputer-based differential protection operating criterion can't be used to use the differential protection of the motor of frequency converter.
[summary of the invention]
The technical problem to be solved in the present invention provides that a kind of amount of calculation is little, speed is fast, is fit to the microcomputer-based differential protection method that frequency-conversion and speed-regulation motor uses.
In order to solve the problems of the technologies described above, the technical solution used in the present invention is that a kind of microcomputer-based differential protection method of frequency-conversion and speed-regulation motor may further comprise the steps:
1) controlled motor being flow to electric current samples respectively with the outflow electric current;
2) directly compare the size that synchronization flows to current sampling data and flows out current sampling data;
3) calculate comparison value number that satisfies fault condition in the period and the ratio that does not satisfy the comparison value number of fault condition;
4) when described ratio during, send the protection actuating signal greater than the numerical value set.
Above-described microcomputer-based differential protection method of frequency-conversion and speed-regulation motor; may further comprise the steps: the power frequency that calculates controlled motor according to current sampling data in real time; according to the real-time length of adjusting the described period of power frequency, the length of described period is directly proportional with the current cycle of controlled motor.The described period is the integral multiple of current cycle, and length is greater than 5 current cycles.
The magnitude relationship of each sampled point of microcomputer-based differential protection method of frequency-conversion and speed-regulation motor comparison of the present invention does not need to calculate the effective value of electric current; so not needing to carry out Fourier calculates; therefore not only amount of calculation is little for this method; reaction speed is fast; because not needing to carry out Fourier calculates; overcome the shortcoming of prior art, can apply to the frequency-conversion and speed-regulation motor microcomputer-based differential protection easily.
[description of drawings]
The present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.
Fig. 1 is a system schematic of implementing microcomputer-based differential protection method of frequency-conversion and speed-regulation motor of the present invention.
Fig. 2 is the flow chart of microcomputer-based differential protection method of frequency-conversion and speed-regulation motor of the present invention.
[embodiment]
As shown in Figure 1, the device of implementing microcomputer-based differential protection method of frequency-conversion and speed-regulation motor of the present invention mainly is made up of signal gathering unit, signal processing unit, CPU element and signal output unit.Signal gathering unit is gathered the current signal at motor two ends in real time; deliver to CPU after treatment; CPU goes out the frequency of electric current according to the calculated signals of sending here; CPU also is responsible for comparing the current signal 1 of synchronization and the size of current signal 2 sampled values; it also wants statistical computation to go out the number of samples that satisfies the number of samples of fault condition and do not satisfy fault condition in the several current cycles of protected equipment in addition; calculate both ratios; when this ratio reaches certain condition; can think that fault has appearred in equipment; satisfied the protection operation condition; CPU externally sends the protection actuating signal immediately, by control unit motor is protected.
Here adopted new differential protection operating criterion, i.e. the real-time differential protection of fixed cycle.
The main points of this criterion are as follows:
(1) as shown in Figure 2; the magnitude relationship that compares synchronization current signal 1 and current signal 2 each sampled value; this is the basis of purchasing into differential protection; because the magnitude relationship that in time compares each sampled point does not need to calculate the effective value of electric current; do not calculate so do not need to carry out Fourier, so the little speed of this method amount of calculation is fast.
(2) be that single sampled value compares because this method adopts; if utilize single comparative result as operating criterion; be easy to misoperation; this method is calculated the number of samples that satisfies the number of samples of fault condition and do not satisfy fault condition in the several current cycles of protected equipment for this reason; thereby calculate both ratios; when this ratio reaches certain condition, can think that fault has appearred in equipment, thus system's output protection actuating signal.
(3) in order to improve the promptness of protection; system calculates the power frequency of protected equipment in real time; guarantee the current cycle (for example be set at 5 current cycles) of operate time of protection for several protected equipment; be that operating criterion is not to judge according to the sampled data in the set time; but judge, thereby satisfying the promptness that improves system protection on the basis of reliability to greatest extent according to the sampled data of current cycle in the time of several protected equipment.
Claims (3)
1. a microcomputer-based differential protection method of frequency-conversion and speed-regulation motor is characterized in that, may further comprise the steps:
1) controlled motor being flow to electric current samples respectively with the outflow electric current;
2) directly compare the size that synchronization flows to current sampling data and flows out current sampling data;
3) calculate comparison value number that satisfies fault condition in the period and the ratio that does not satisfy the comparison value number of fault condition;
4) when described ratio during, send the protection actuating signal greater than the numerical value set.
2. microcomputer-based differential protection method of frequency-conversion and speed-regulation motor according to claim 1; it is characterized in that; may further comprise the steps: the power frequency that calculates controlled motor according to current sampling data in real time; according to the real-time length of adjusting the described period of power frequency, the length of described period is directly proportional with the current cycle of controlled motor.
3. microcomputer-based differential protection method of frequency-conversion and speed-regulation motor according to claim 1 is characterized in that, the described period is the integral multiple of current cycle, and length is greater than 5 current cycles.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010101462264A CN101814718B (en) | 2010-04-07 | 2010-04-07 | Microcomputer-based differential protection method of frequency-conversion and speed-regulation motor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010101462264A CN101814718B (en) | 2010-04-07 | 2010-04-07 | Microcomputer-based differential protection method of frequency-conversion and speed-regulation motor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101814718A true CN101814718A (en) | 2010-08-25 |
| CN101814718B CN101814718B (en) | 2012-08-22 |
Family
ID=42621870
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010101462264A Expired - Fee Related CN101814718B (en) | 2010-04-07 | 2010-04-07 | Microcomputer-based differential protection method of frequency-conversion and speed-regulation motor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101814718B (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101976820A (en) * | 2010-08-31 | 2011-02-16 | 南京南瑞继保电气有限公司 | Processing method of protection sampling signals of variable-frequency electric motor protection device |
| CN102013665A (en) * | 2010-12-01 | 2011-04-13 | 江苏金智科技股份有限公司 | Motor differential protection method under a mode for dragging motor by high-voltage frequency converter |
| CN102623960A (en) * | 2012-04-12 | 2012-08-01 | 台州发电厂 | Variable-frequency motor protection device based on intelligent sensors |
| CN104993457A (en) * | 2015-07-21 | 2015-10-21 | 大唐三门峡发电有限责任公司 | Thermal power plant high-voltage variable frequency motor protection system |
| CN107741520A (en) * | 2017-10-20 | 2018-02-27 | 国电南瑞科技股份有限公司 | A kind of overexcitation times number calculating method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7301743B2 (en) * | 2005-06-28 | 2007-11-27 | Vassili Rozine | Device and a method for advanced protection from short circuit current |
| CN100420114C (en) * | 2005-01-14 | 2008-09-17 | 北京四方继保自动化股份有限公司 | Anti-TA transient imbalance differential protection for generator |
-
2010
- 2010-04-07 CN CN2010101462264A patent/CN101814718B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100420114C (en) * | 2005-01-14 | 2008-09-17 | 北京四方继保自动化股份有限公司 | Anti-TA transient imbalance differential protection for generator |
| US7301743B2 (en) * | 2005-06-28 | 2007-11-27 | Vassili Rozine | Device and a method for advanced protection from short circuit current |
Non-Patent Citations (2)
| Title |
|---|
| 《中国电机工程学报》 20030930 杨经超，等 采样值差动保护动作特性的研究 71-77 1-3 第23卷, 第9期 2 * |
| 《电力自动化设备》 19961130 陈德树，等 采样值电流差动微机保护的一些问题 3-8 1 , 第4期 2 * |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101976820A (en) * | 2010-08-31 | 2011-02-16 | 南京南瑞继保电气有限公司 | Processing method of protection sampling signals of variable-frequency electric motor protection device |
| CN102013665A (en) * | 2010-12-01 | 2011-04-13 | 江苏金智科技股份有限公司 | Motor differential protection method under a mode for dragging motor by high-voltage frequency converter |
| CN102623960A (en) * | 2012-04-12 | 2012-08-01 | 台州发电厂 | Variable-frequency motor protection device based on intelligent sensors |
| CN102623960B (en) * | 2012-04-12 | 2014-02-05 | 台州发电厂 | Variable-frequency motor protection device based on intelligent sensors |
| CN104993457A (en) * | 2015-07-21 | 2015-10-21 | 大唐三门峡发电有限责任公司 | Thermal power plant high-voltage variable frequency motor protection system |
| CN107741520A (en) * | 2017-10-20 | 2018-02-27 | 国电南瑞科技股份有限公司 | A kind of overexcitation times number calculating method |
| CN107741520B (en) * | 2017-10-20 | 2020-02-04 | 国电南瑞科技股份有限公司 | Overexcitation multiple calculation method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101814718B (en) | 2012-08-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101814718B (en) | Microcomputer-based differential protection method of frequency-conversion and speed-regulation motor | |
| CN102185283B (en) | Method for sub-synchronous current calculation and sub-synchronous over-current and divergent protection of generator | |
| CN100593891C (en) | Current protection control method and device for 24kV vacuum breaker | |
| CN104218543B (en) | Current source type converter differential protecting method | |
| CN101976820A (en) | Processing method of protection sampling signals of variable-frequency electric motor protection device | |
| CN101795084A (en) | Thyristor rectifier bridge parallel operation full digital current homogenizing control device | |
| CN103728998A (en) | Intelligent adjustment type heat dissipation method and system for high-voltage frequency converter | |
| CN102136716A (en) | Grid frequency detection method based on phase locked loop technology | |
| CN102074940A (en) | Current differential protection method for direct current system circuit | |
| CN103532466B (en) | Method and device for controlling torque change rate of permanent magnet synchronous motor | |
| CN102222932A (en) | Isolated island detecting device and method based on load characteristic | |
| CN101266265B (en) | Method for detecting high voltage frequency converter electric network voltage phase | |
| CN110011333B (en) | Energy storage power station, frequency modulation control method and storage medium | |
| CN101908753B (en) | Current differential protection method automatically adaptive to variable frequency motor | |
| CN102215027A (en) | Cascade speed control device | |
| CN104092201B (en) | Remote ultra-high voltage alternating-current transmission line fault determination method | |
| CN101710689B (en) | Method for protecting strong feed-in line current | |
| CN103683293B (en) | A kind of APF harmonic is selected and capacity limit control method | |
| CN209881381U (en) | Circuit breaker protection module with direct current and broadband measurement function | |
| CN103248025A (en) | Lossy electric transmission line current traveling-wave differential protection method | |
| CN102621373B (en) | Signal collection device and signal processing method of current-sharing input system of alternating-current power supply | |
| CN109298361A (en) | Accident analysis preprocess method based on transient state recording type fault detector | |
| CN110736869B (en) | Current separation method, device and equipment for single-phase circuit | |
| CN209462234U (en) | A kind of Synchronous Motor Excitation System | |
| CN102142668A (en) | Overcurrent rapid-disconnection protection circuit based on digital control potentiometer technology |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120822 Termination date: 20190407 |