CN209562144U - A kind of frequency tracking apparatus for frequency converter back end current channel - Google Patents
A kind of frequency tracking apparatus for frequency converter back end current channel Download PDFInfo
- Publication number
- CN209562144U CN209562144U CN201822236040.2U CN201822236040U CN209562144U CN 209562144 U CN209562144 U CN 209562144U CN 201822236040 U CN201822236040 U CN 201822236040U CN 209562144 U CN209562144 U CN 209562144U
- Authority
- CN
- China
- Prior art keywords
- frequency
- protection
- generator terminal
- neutral conductor
- motor
- 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
Abstract
The utility model discloses a kind of frequency tracking apparatus for frequency converter back end current channel; CT (3), the neutral conductor is once protected once to protect CT (4), generator terminal second protection CT (5), neutral conductor second protection CT (6), the dedicated CT of frequency measurement (7) and adjustable frequency motor differential protection unit (8) including frequency converter (1), by protection motor (2), generator terminal; frequency measurement is carried out by the current signal of frequency converter rear end, without additional addition voltage transformer；The utility model can satisfy accurate frequency measurement and progress automatic frequency tracking sampling of the inverter motor under any load and working frequency, provide the requirement of authentic data for adjustable frequency motor differential protection.
Description
Technical field
The utility model relates to a kind of sample frequency tracking systems and method for frequency converter back end current channel, belong to
Technical field of electric power.
Background technique
In power plant and industrial enterprise, adjustable frequency motor is essential primary equipment, is especially subtracted in national energy-saving
Under the guidance of row's policy, adjustable frequency motor using more and more.According to " 5153 thermal power plant station service of DL/T designs skill
Art regulation " requirement, for 2000kW or more and 2000kW or less current quick sensitivity be unsatisfactory for require motor
Differential protection must be installed, but frequency-converter device does not provide differential protection function generally, it is therefore desirable to separately set protective device
Differential protection is provided to the motor of frequency converter rear end.The difference stream of motor generator terminal and neutral point that the differential protection uses carries out
Differential protection calculates, and differential protection is based on the power frequency on electric current and sample frequency basis, exported due to frequency converter
Range is relatively wide (10~60Hz), therefore only correctly progress frequency-tracking can just be computed correctly stream of going on business, and carry out differential protection
Logical process.If frequency meter is not calculated accurately, the difference stream for sampling out using the frequency-tracking is also inaccuracy, to influence
The Reliability of Microprocessor of protection.
Conventional frequency measuring method is generally used zero crossing frequency measurement, can be hardware zero crossing or software zero crossing frequency measurement, leads to
It crosses and calculates the time width of AC signal zero crossing point twice and calculate its frequency.But this method influence from harmonic is larger, in high order
In the larger situation of harmonic wave accounting, the time width of zero crossing can not precise measurement, so that calculated frequency departure will be larger.
And zero crossing frequency measurement will generally be used for amplitude and change little AC signal, such as voltage.For the magnitude of current, due to its variation
Range is larger, and under motor underloading, heavy duty and fault condition, current amplitude can be very different, if still using zero passage
Point frequency measurement, then be unable to satisfy sampling precision requirement.
Utility model content
Purpose of utility model: in order to overcome the deficiencies in the prior art, the utility model provides a kind of for frequency conversion
The frequency tracking apparatus in device back end current channel meets accurate frequency measurement of the inverter motor under any load and working frequency
And carry out automatic frequency tracking sampling.
Technical solution: to achieve the above object, the technical solution adopted in the utility model are as follows:
A kind of frequency tracking apparatus for frequency converter back end current channel, including frequency converter, by protection motor, generator terminal
Primary protection CT, the neutral conductor once protect CT, generator terminal second protection CT, neutral conductor second protection CT, the dedicated CT of frequency measurement and change
Frequency motor differential protection unit is responsible for power supply by frequency converter by protection motor.Generator terminal once protects CT to connect by protection electricity
Between motivation and frequency converter, secondary current signal one will be converted to by the generator terminal three-phase current of protection motor, the neutral conductor is primary
Protection CT connects on by the protection motor neutral conductor, will be converted to secondary current signal by protection motor neutral conductor three-phase current
Two, no-load voltage ratio once protects CT consistent with generator terminal.Generator terminal second protection CT access generator terminal once protects the secondary current signal of CT
One, the neutral conductor second protection CT access neutral conductor once protect the secondary current signal two of CT, and the dedicated CT of frequency measurement accesses generator terminal one
The secondary current signal one of secondary protection CT, the signal that generator terminal second protection CT, neutral conductor second protection CT, the dedicated CT of frequency measurement are measured
It is input in the AD circuit of adjustable frequency motor differential protection unit, AD circuit samples these signals.Adjustable frequency motor is poor
Dynamic protection location is connect with the dedicated CT of frequency measurement, generator terminal second protection CT, neutral conductor second protection CT respectively.
Preferred: it is mutual inductor that generator terminal, which once protects CT, the neutral conductor once to protect CT,.
Preferred: secondary current signal one is rated for 5A or 1A.
Preferred: generator terminal second protection CT and neutral conductor second protection CT needs to meet wanting for measurement accuracy under 20 times of In
It asks.
Preferred: the dedicated CT of frequency measurement meets the requirement of measurement accuracy under 1.2In.
The utility model compared with prior art, has the advantages that
The current signal that the utility model directly passes through frequency converter rear end carries out frequency measurement, without additional addition mutual induction of voltage
Device.The conversion since common second protection CT no-load voltage ratio is larger is solved when motor operates normally using the dedicated CT of high-precision frequency measurement
Digital signal amount afterwards is smaller, and the problem of influence conventional software frequency-measurement accuracy.It is electronic that the utility model can satisfy frequency converter
Accurate frequency measurement and progress automatic frequency tracking sampling of the machine under any load and working frequency, are the differential guarantor of adjustable frequency motor
Shield provides the requirement of authentic data.
Detailed description of the invention
Fig. 1 is the electrical schematic diagram and wiring schematic diagram of the utility model.
In figure: 1-frequency converter, 2-by protection motor, and 3-generator terminals once protect CT, and the 4-neutral conductors once protect CT, 5-machines
Hold second protection CT, 6-neutral conductor second protection CT, the dedicated CT of 7-frequency measurements (three-phase), 8-adjustable frequency motor differential protection units.
Specific embodiment
In the following with reference to the drawings and specific embodiments, the utility model is furtherd elucidate, it should be understood that these examples are only used for
Bright the utility model rather than limitation the scope of the utility model, after having read the utility model, those skilled in the art
Member falls within the application range as defined in the appended claims to the modification of the various equivalent forms of the utility model.
A kind of frequency tracking apparatus for frequency converter back end current channel, as shown in Figure 1, including frequency converter 1, being protected
Motor 2, generator terminal once protect CT3, the neutral conductor once protect CT4, generator terminal second protection CT5, neutral conductor second protection CT6,
The dedicated CT7 of frequency measurement and adjustable frequency motor differential protection unit 8, generator terminal once protect CT3 electronic for acquiring frequency converter rear end
The current signal of machine generator terminal, the neutral conductor once protect CT4 for acquiring frequency converter rear end motor neutral current signal.
Power supply is responsible for by frequency converter 1 by protection motor 2.Generator terminal is once protected CT3 (current transformer) to connect and is being protected
Between motor 2 and frequency converter 1, secondary current signal one, secondary electricity will be converted to by the generator terminal three-phase current of protection motor 2
Stream signal one is rated for 5A or 1A.The neutral conductor once protects CT4 (current transformer) to connect by 2 neutral conductor of protection motor
On, secondary current signal two will be converted to by 2 neutral conductor three-phase current of protection motor, no-load voltage ratio and generator terminal once protect CT3
Unanimously.Generator terminal second protection CT5 access generator terminal once protects the secondary current signal one of CT3, and secondary current signal one is converted
For the voltage signal that adjustable frequency motor differential protection unit 8 can be sampled by AD, neutral conductor second protection CT6 access neutrality
Line once protects the secondary current signal two of CT4, and secondary current signal two is converted to adjustable frequency motor differential protection unit 8 can
The voltage signal sampled by AD, the dedicated CT7 access generator terminal of frequency measurement once protect the secondary current signal one of CT3, generator terminal
The signal that second protection CT5, neutral conductor second protection CT6, the dedicated CT7 of frequency measurement are measured is input to adjustable frequency motor differential protection list
In the AD circuit of member 8, AD circuit samples these signals.Adjustable frequency motor differential protection unit 8 is according to the dedicated CT7 of frequency measurement
The current signal of sampling carries out frequency calculating, and dynamic sampling rate adjusting.Simultaneously according to generator terminal second protection CT5, the neutral conductor
The respective ABC three-phase current signal of second protection CT6 carries out differential current computing to realize phase segregated differential protection.
Generator terminal second protection CT 5 and the general no-load voltage ratio of neutral conductor second protection CT 6 are larger, need to meet and survey under 20 times of In
The requirement of accuracy of measurement.The dedicated CT 7 of frequency measurement accesses the secondary current signal that generator terminal once protects CT 3, and the dedicated CT of frequency measurement uses high
The secondary CT of the measurement of precision becomes smaller, general satisfaction 1.2In.
The emphasis of the utility model is the power frequency of correct measurement inverter output terminal, due to the frequency range of the electric current
It changes greatly, generally 10~60Hz.It is humorous that certain high order has been superimposed and due to the characteristic of frequency converter, on the output electric current
Wave, can not the precise measurement frequency using common Frequency Measurement Algorithm.Software zero crossing and Fourier is used in combination in the utility model
Frequency Measurement Algorithm, the signal that secondary CT 7 dedicated to frequency measurement is exported carry out frequency measurement and tracking, and specific frequency measurement processing logic is as follows:
Step S1: it is special that the AD circuit of adjustable frequency motor differential protection unit 8 presses every 36 point sampling three-phase frequency measurement of cycle first
The signal exported with CT 7, the value of sampled point are respectively labeled as ia、ib、ic, calculate if=ia+ib-ic, with ifAs frequency measurement data
It can also guarantee that Frequency Measurement Algorithm is working properly in the case of input, road any in this way or two-way CT broken string.
Step S2: due to the output frequency not necessarily 50Hz of current frequency converter 1, so if directlying adopt Fourier
Frequency measurement can not calculate correct frequency, at this time, it may be necessary to use zero crossing Frequency Measurement Algorithm first, calculate the input of frequency measurement data
ifGeneral frequency values, it is assumed that calculated frequency values are f1。
Step S3: the AD circuit sampling frequency of switching adjustable frequency motor differential protection unit 8 is 36 × f1, and with the sampling
The data of frequency sampling at least two cycle, to obtain frequency measurement data if1。
Step S4, using Fourier's Frequency Measurement Algorithm to if1Data carry out frequency measurement calculating, obtain preliminary frequency values f2。
Step S5, the AD circuit sampling frequency for switching adjustable frequency motor differential protection unit 8 is 36 × f2, and with the sampling
The data of frequency sampling at least two cycle, to obtain frequency measurement data if2。
Step S6, step S4 and step S5, Approach by inchmeal are repeated, and obtains final frequency values f.
Step S7, carry out tracking sampling generator terminal second protection CT5's and neutral conductor second protection CT6 using frequency values f
Current value, and complete differential protection calculating.
The utility model is simple and effective, fast response time, high reliablity, is applicable in frequency range extensively (10~60Hz), secondary
Electric current accurate frequency measurement of energy within the scope of 0.05In~1.2In, can be just being superimposed higher harmonic component on electric current
Frequency values are really calculated, well adapting to property fully meets requirement of the frequency converter differential protection for frequency-tracking.
The above is only the preferred embodiment of the utility model, it should be pointed out that: for the common skill of the art
For art personnel, without departing from the principle of this utility model, several improvements and modifications can also be made, these improve and
Retouching also should be regarded as the protection scope of the utility model.
Claims (5)
1. a kind of frequency tracking apparatus for frequency converter back end current channel, it is characterised in that: including frequency converter (1), protected
Shield motor (2), generator terminal once protect CT (3), the neutral conductor once to protect CT (4), generator terminal second protection CT (5), the neutral conductor two
Secondary protection CT (6), the dedicated CT of frequency measurement (7) and adjustable frequency motor differential protection unit (8), by protection motor (2) by frequency conversion
Device (1) is responsible for power supply；Generator terminal once protects CT (3) to connect by between protection motor (2) and frequency converter (1), will be protected electricity
The generator terminal three-phase current of motivation (2) is converted to secondary current signal one, and the neutral conductor once protects CT (4) to connect by protection motor
(2) on the neutral conductor, secondary current signal two, no-load voltage ratio and generator terminal will be converted to by protection motor (2) neutral conductor three-phase current
Primary protection CT (3) is consistent；Generator terminal second protection CT (5) access generator terminal once protects the secondary current signal one of CT (3), neutral
Line second protection CT (6) the access neutral conductor once protects the secondary current signal two of CT (4), and the dedicated CT of frequency measurement (7) accesses generator terminal
The secondary current signal one of primary protection CT (3), generator terminal second protection CT (5), neutral conductor second protection CT (6), frequency measurement are dedicated
The signal that CT (7) is measured is input in the AD circuit of adjustable frequency motor differential protection unit (8), and AD circuit carries out these signals
Sampling；Adjustable frequency motor differential protection unit (8) respectively with the dedicated CT of frequency measurement (7), generator terminal second protection CT (5), the neutral conductor two
Secondary protection CT (6) connection.
2. being used for the frequency tracking apparatus in frequency converter back end current channel according to claim 1, it is characterised in that: generator terminal one
It is mutual inductor that secondary protection CT (3), the neutral conductor, which once protect CT (4),.
3. being used for the frequency tracking apparatus in frequency converter back end current channel according to claim 1, it is characterised in that: secondary electricity
Stream signal one is rated for 5A or 1A.
4. being used for the frequency tracking apparatus in frequency converter back end current channel according to claim 1, it is characterised in that: generator terminal two
Secondary protection CT (5) and neutral conductor second protection CT (6) need to meet the requirement of measurement accuracy under 20 times of In.
5. being used for the frequency tracking apparatus in frequency converter back end current channel according to claim 1, it is characterised in that: frequency measurement is special
Meet the requirement of measurement accuracy under 1.2In with CT (7).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201822236040.2U CN209562144U (en) | 2018-12-28 | 2018-12-28 | A kind of frequency tracking apparatus for frequency converter back end current channel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201822236040.2U CN209562144U (en) | 2018-12-28 | 2018-12-28 | A kind of frequency tracking apparatus for frequency converter back end current channel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN209562144U true CN209562144U (en) | 2019-10-29 |
Family
ID=68304326
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201822236040.2U Active CN209562144U (en) | 2018-12-28 | 2018-12-28 | A kind of frequency tracking apparatus for frequency converter back end current channel |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN209562144U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110120655A (en) * | 2018-12-28 | 2019-08-13 | 江苏金智科技股份有限公司 | A kind of frequency-tracking system and method for frequency converter back end current channel |
-
2018
- 2018-12-28 CN CN201822236040.2U patent/CN209562144U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110120655A (en) * | 2018-12-28 | 2019-08-13 | 江苏金智科技股份有限公司 | A kind of frequency-tracking system and method for frequency converter back end current channel |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Emanuel | Summary of IEEE standard 1459: definitions for the measurement of electric power quantities under sinusoidal, nonsinusoidal, balanced, or unbalanced conditions | |
| AU2009337631B2 (en) | Three-phase electric energy measurement apparatus | |
| US8014964B1 (en) | Electrical power and energy measurement method and apparatus | |
| CN106771645B (en) | Capacitance type potential transformer dielectric loss and capacitance on-line monitoring method and monitoring system | |
| Kaczmarek et al. | Proposal for extension of routine tests of the inductive current transformers to evaluation of transformation accuracy of higher harmonics | |
| Suslov et al. | Separate measurement of fundamental and high harmonic energy at consumer inlet—A real way to improve supply network voltage waveform | |
| CN102175925A (en) | Measuring device for measuring capacitance in parallel capacitor bank | |
| CN103809010A (en) | Device and method for determining voltage and power of each phase of medium-voltage network | |
| CN202002977U (en) | Measuring device for measuring capacitance of shunt capacitor group | |
| CN111123162A (en) | Three-phase transformer short-circuit parameter online monitoring method based on fundamental wave positive sequence component | |
| CN112098916A (en) | System and method for superposing ripples on direct current loop in direct current electric energy detection device | |
| WO2013106922A1 (en) | System and method for linear measurement of ac waveforms with low voltage non-linear sensors in high voltage environments | |
| Orts-Grau et al. | Discussion on useless active and reactive powers contained in the IEEE standard 1459 | |
| Hosono et al. | Suppression and measurement of arc furnace flicker with a large static var compensator | |
| CN209562144U (en) | A kind of frequency tracking apparatus for frequency converter back end current channel | |
| CN112561312B (en) | Power quality factor-based power distribution network line loss calculation method and system | |
| Gaunt et al. | True power factor metering for m-wire systems with distortion, unbalance and direct current components | |
| CN110120655A (en) | A kind of frequency-tracking system and method for frequency converter back end current channel | |
| Tangsunantham et al. | Voltage unbalance measurement in three-phase smart meter applied to AMI systems | |
| Canturk et al. | On the definition of apparent power | |
| CN110146780A (en) | Isolated neutral flexibility distribution network system ferromagnetic resonance method of discrimination | |
| CN103176030B (en) | The harmonic detection method of distribution system | |
| Kalair et al. | Steady-state and time-varying harmonics in distribution system | |
| CN104345218A (en) | Reactance value measurement system and method for three-phase reactor | |
| Xian-chun et al. | Design of three-phase multi-purpose standard electric energy meter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |