CN112269056A - A hardware frequency measurement circuit of a high-voltage variable frequency relay protection device - Google Patents
A hardware frequency measurement circuit of a high-voltage variable frequency relay protection device Download PDFInfo
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- CN112269056A CN112269056A CN202011076926.0A CN202011076926A CN112269056A CN 112269056 A CN112269056 A CN 112269056A CN 202011076926 A CN202011076926 A CN 202011076926A CN 112269056 A CN112269056 A CN 112269056A
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
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Abstract
本发明涉及一种高压变频继电保护装置的硬件测频电路，包括单相测频模块，单相测频模块接收对应电压互感器采集的二次电压信号，进行频率测量；降压单元将电压互感器输出的二次电压信号进行降压后输入到整流单元，整流单元整流为直流信号输出；经滤波单元滤波，放大单元对波形放大后，经光耦隔离后输入到测量单元；测量单元进行对输入信号进行频率测量。采用三种相同回路提高频率测量的稳定性、精度，而且还能在系统发生故障时准确为处理器提供可靠的频率计算信号源，能实时、可靠转换电力系统的频率变化。采用的模拟回路与数字回路的隔离方法，能进一步提高电路运行的稳定性与可靠性。
The invention relates to a hardware frequency measurement circuit of a high-voltage variable frequency relay protection device, comprising a single-phase frequency measurement module, the single-phase frequency measurement module receives a secondary voltage signal collected by a corresponding voltage transformer, and performs frequency measurement; The secondary voltage signal output by the transformer is depressurized and then input to the rectifier unit, and the rectifier unit rectifies the output of the DC signal; after filtering by the filter unit, the amplifying unit amplifies the waveform, and then is isolated by the optocoupler and then input to the measuring unit; Make frequency measurements on the input signal. Three identical loops are used to improve the stability and accuracy of frequency measurement, and can accurately provide a reliable frequency calculation signal source for the processor when the system fails, and can convert the frequency change of the power system in real time and reliably. The adopted method of isolating the analog loop and the digital loop can further improve the stability and reliability of the circuit operation.
Description
Technical Field
The invention relates to the technical field of power system relay protection, in particular to a hardware frequency measurement circuit of a high-voltage variable-frequency relay protection device.
Background
At present, microcomputer protection products are used in the field of relay protection of power systems to realize the fault protection function of the power systems, wherein the frequency measurement of the system is crucial to the microcomputer protection products, and is not only related to the data sampling calculation of the relay protection products, but also influences the stable operation monitoring function of the system; meanwhile, the current high-voltage motor generally adopts a frequency conversion starting and running mode, and has the biggest characteristics of wider frequency variation range and higher requirement on frequency sampling.
At present, frequency calculation methods adopted by relay protection devices of existing power systems are all realized based on software algorithms. At present, a method for calculating the frequency of a power system by using a software algorithm is easily influenced by interference signals on a sampled waveform, particularly when the power system has a fault or a high-voltage motor is started and a load is large, waveform distortion is serious, the distortion degree of the waveform cannot be predicted by the software algorithm, so that the error of a frequency calculation result is large, and the function of a relay protection product is influenced.
Disclosure of Invention
In order to solve the problem that the frequency sampling of a relay protection product of a power system is unstable and reliable, the invention provides a hardware frequency measurement circuit of a high-voltage variable-frequency relay protection device, so that when the relay protection product has a fault or runs abnormally, the frequency of the system can be correctly calculated, the data sampling precision and stability of the relay protection product are improved, and the function of the product is further improved.
In order to achieve the aim, the invention provides a hardware frequency measurement circuit of a high-voltage variable-frequency relay protection device, which comprises a single-phase frequency measurement module, wherein the single-phase frequency measurement module receives a secondary voltage signal acquired by a corresponding voltage transformer and carries out frequency measurement;
the single-phase frequency measurement module comprises a voltage reduction unit, a rectification unit, a filtering unit, an amplification unit, a light coupler and a measurement unit;
the voltage reduction unit is used for reducing the voltage of a secondary voltage signal output by the voltage transformer and then inputting the secondary voltage signal into the rectification unit, and the rectification unit is used for rectifying the secondary voltage signal into a direct current signal and outputting the direct current signal; the filtering unit filters the direct current signal, the amplifying unit amplifies the filtered signal, and the amplified signal is input to the measuring unit after optical coupling isolation; the measuring unit performs frequency measurement on the input signal.
Further, the number of the single-phase frequency measurement modules is 3, and the single-phase frequency measurement modules are respectively connected to 3-phase voltage transformers.
Further, the voltage reduction unit is divided by series resistors.
Further, the rectifying unit is a full-wave rectifying bridge formed by four diodes.
Further, the filtering unit comprises a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2; one end of the resistor R1 is connected with one output end of the full-wave rectifier bridge, the other end of the resistor R1 is connected with one end of the capacitor C1, and the other output end of the full-wave rectifier bridge at the other end of the capacitor C1 is grounded; one end of the resistor R2 is connected with one end of the C1, and the other end is connected with one end of the capacitor C2; the other terminal of the capacitor C2 is connected to ground.
Further, the amplifying unit includes an operational amplifier, a resistor R3, and a resistor R4;
one end of the resistor R3 is connected with one end of the capacitor C2, the other end of the resistor R3 is connected with the positive input end of the operational amplifier, and the negative input end of the operational amplifier is grounded; the resistor R4 is connected between the positive input terminal and the output terminal of the operational amplifier.
Further, the device also comprises a diode D2 and a current limiting resistor R5; the anode of the diode D2 is connected with the output end of the operational amplifier, the cathode is connected with one end of the current limiting resistor R5, and the other end of the current limiting resistor R5 is connected with the positive input end of the optocoupler.
Further, the negative input end of the optocoupler is grounded; the positive output end of the optical coupler is connected with the input port of the measuring unit, and the measuring unit measures the frequency of the input signal.
The technical scheme of the invention has the following beneficial technical effects:
the invention converts the frequency signal of the power system into the digital signal which can be directly processed by the processor by using the analog circuit, improves the stability and the precision of frequency measurement by adopting three same loops, can accurately provide a reliable frequency calculation signal source for the processor when the system fails, and can reliably convert the frequency change of the power system in real time. The adopted method for isolating the analog loop from the digital loop can further improve the stability and the reliability of the operation of the circuit.
Drawings
Fig. 1 is a schematic diagram of a single-phase hardware frequency measurement circuit.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
Fig. 1 is a schematic diagram of a single-phase frequency measurement module. The voltage frequency of a certain phase can be tested independently, the voltage frequency of 3 phases can be measured by adopting three same single-phase frequency measurement modules respectively, the instability of frequency sampling signals caused by a certain phase grounding is prevented, and the reliability of frequency calculation can be improved.
The single-phase frequency measurement module comprises a voltage reduction unit, a rectification unit, a filtering unit, an amplification unit, a light coupler and a measurement unit; the voltage reduction unit is used for reducing the voltage of a secondary voltage signal output by the voltage transformer and then inputting the secondary voltage signal into the rectification unit, and the rectification unit is used for rectifying the secondary voltage signal into a direct current signal and outputting the direct current signal; the filtering unit filters the direct current signal, the amplifying unit amplifies the filtered signal, and the amplified signal is input to the measuring unit after optical coupling isolation; the measuring unit performs frequency measurement on the input signal.
The voltage reduction unit comprises voltage reduction resistors R8 and R9, a secondary voltage signal U output by the three-phase voltage mutual inductance is respectively connected into the full-wave rectifier bridge through the voltage reduction resistors R8 and R9, and the rectifier bridge outputs a pulsating direct current signal which is filtered through a resistor capacitor and outputs a basic electric signal of the hardware frequency measurement circuit. The filtering unit comprises a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2; one end of the resistor R1 is connected with one output end of the full-wave rectifier bridge, the other end of the resistor R1 is connected with one end of the capacitor C1, and the other output end of the full-wave rectifier bridge at the other end of the capacitor C1 is grounded; one end of the resistor R2 is connected with one end of the C1, and the other end is connected with one end of the capacitor C2; the other end of the capacitor C2 is grounded.
The output basic electrical signal of the hardware frequency measuring circuit is amplified, and the amplifying unit comprises an operational amplifier, a resistor R3 and a resistor R4; one end of the resistor R3 is connected with one end of the capacitor C2, the other end of the resistor R3 is connected with the positive input end of the operational amplifier, and the negative input end of the operational amplifier is grounded; the resistor R4 is connected between the positive input terminal and the output terminal of the operational amplifier. Resistor R4 adjusts the amplification of the amplifier.
The signal output by the operational amplifier passes through a reverse diode D2 and then is connected to an emitter of an optocoupler U1 through a current limiting resistor R5 to be used as a driving and judging signal of the optocoupler isolator.
The receiving stage of the optocoupler U1 outputs a distinguishing signal of a frequency wave crest and a frequency wave trough through a current-limiting resistor and a resistor-capacitor filtering loop, the distinguishing signal can be input to an I/O pin of a microprocessor, and the circuit adopts two paths of isolation power supplies for power supply, and isolates an analog circuit and a digital circuit.
The rectifier bridge converts alternating current wave crest and wave trough signals into pulsating direct current signals, so that a post-stage circuit does not need positive and negative double power supplies, and the frequency sampling discrimination speed of the product is also improved.
The reverse diode adopts a fast diode to improve the reliability of the circuit and also can prevent the reverse flow of an electric signal.
The alternating current voltage signal outputs a pulsating direct current signal through the rectifier bridge, and the pulsating direct current signal is output to the optical coupling isolation device through the comparison amplification loop of the operational amplifier, so that a stable and reliable signal source is provided for the system frequency sampling calculation processor.
In summary, the present invention relates to a hardware frequency measurement circuit of a high-voltage variable-frequency relay protection device, which includes a single-phase frequency measurement module, where the single-phase frequency measurement module receives a secondary voltage signal collected by a corresponding voltage transformer to perform frequency measurement; the voltage reduction unit is used for reducing the voltage of a secondary voltage signal output by the voltage transformer and then inputting the signal into the rectification unit, and the rectification unit is used for rectifying the signal into a direct current signal and outputting the direct current signal; after the signals are filtered by the filtering unit and amplified by the amplifying unit, the signals are input to the measuring unit through optical coupling isolation; the measuring unit performs frequency measurement on the input signal. The three same loops are adopted, so that the stability and the precision of frequency measurement can be improved, a reliable frequency calculation signal source can be accurately provided for a processor when a system fails, and the frequency change of a power system can be reliably converted in real time. The adopted method for isolating the analog loop from the digital loop can further improve the stability and the reliability of the operation of the circuit.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention shall be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.
Claims (8)
1. A hardware frequency measurement circuit of a high-voltage variable-frequency relay protection device is characterized by comprising a single-phase frequency measurement module, wherein the single-phase frequency measurement module receives a secondary voltage signal acquired by a corresponding voltage transformer and carries out frequency measurement;
the single-phase frequency measurement module comprises a voltage reduction unit, a rectification unit, a filtering unit, an amplification unit, an optical coupler and a measurement unit;
the voltage reduction unit is used for reducing the voltage of a secondary voltage signal output by the voltage transformer and then inputting the secondary voltage signal into the rectification unit, and the rectification unit is used for rectifying the secondary voltage signal into a direct current signal and outputting the direct current signal; the filtering unit filters the direct current signal, the amplifying unit amplifies the filtered signal, and the amplified signal is input to the measuring unit after optical coupling isolation; the measuring unit performs frequency measurement on the input signal.
2. The hardware frequency measurement circuit of the high-voltage variable-frequency relay protection device according to claim 1, wherein the number of the single-phase frequency measurement modules is 3, and the single-phase frequency measurement modules are respectively connected to 3-phase voltage transformers.
3. The hardware frequency measurement circuit of the high-voltage variable-frequency relay protection device according to claim 1 or 2, wherein the voltage reduction unit divides voltage by a series resistor.
4. The hardware frequency measurement circuit of the high-voltage variable-frequency relay protection device according to claim 1 or 2, wherein the rectifying unit is a full-wave rectifying bridge formed by four diodes.
5. The hardware frequency measurement circuit of the high-voltage variable-frequency relay protection device according to claim 4, wherein the filter unit comprises a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2; one end of the resistor R1 is connected with one output end of the full-wave rectifier bridge, the other end of the resistor R1 is connected with one end of the capacitor C1, and the other output end of the full-wave rectifier bridge at the other end of the capacitor C1 is grounded; one end of the resistor R2 is connected with one end of the C1, and the other end is connected with one end of the capacitor C2; the other terminal of the capacitor C2 is connected to ground.
6. The hardware frequency measurement circuit of the high-voltage variable-frequency relay protection device according to claim 4, wherein the amplifying unit comprises an operational amplifier, a resistor R3 and a resistor R4;
one end of the resistor R3 is connected with one end of the capacitor C2, the other end of the resistor R3 is connected with the positive input end of the operational amplifier, and the negative input end of the operational amplifier is grounded; the resistor R4 is connected between the positive input terminal and the output terminal of the operational amplifier.
7. The hardware frequency measuring circuit of the high-voltage frequency-conversion relay protection device according to claim 6, further comprising a diode D2 and a current-limiting resistor R5; the anode of the diode D2 is connected with the output end of the operational amplifier, the cathode is connected with one end of the current limiting resistor R5, and the other end of the current limiting resistor R5 is connected with the positive input end of the optocoupler.
8. The hardware frequency measurement circuit of the high-voltage variable-frequency relay protection device according to claim 7, wherein a negative input end of the optical coupler is grounded; the positive output end of the optical coupler is connected with the input port of the measuring unit, and the measuring unit measures the frequency of the input signal.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011076926.0A CN112269056B (en) | 2020-10-10 | 2020-10-10 | A hardware frequency measurement circuit for high voltage variable frequency relay protection device |
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| CN202011076926.0A CN112269056B (en) | 2020-10-10 | 2020-10-10 | A hardware frequency measurement circuit for high voltage variable frequency relay protection device |
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| CN112269056A true CN112269056A (en) | 2021-01-26 |
| CN112269056B CN112269056B (en) | 2024-04-12 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114578114A (en) * | 2022-02-28 | 2022-06-03 | 特变电工西安电气科技有限公司 | SVG power module bypass state detection circuit |
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| US3991365A (en) * | 1974-10-31 | 1976-11-09 | Hewlett-Packard Company | Instantaneous frequency measurement system |
| CN201859177U (en) * | 2010-09-29 | 2011-06-08 | 南京安能电气控制设备有限公司 | Measurement module for low-frequency alternating current signal in relay protection device |
| CN103913659A (en) * | 2014-03-30 | 2014-07-09 | 河北工业大学 | Instantaneous protection tester and operation method thereof |
| CN204241562U (en) * | 2014-11-19 | 2015-04-01 | 瓮福（集团）有限责任公司 | A kind of frequency detection circuit based on LPC2132 microcontroller |
| CN209624682U (en) * | 2019-01-18 | 2019-11-12 | 华能瑞金发电有限责任公司 | A kind of electric system primary frequency control system frequency measuring device |
-
2020
- 2020-10-10 CN CN202011076926.0A patent/CN112269056B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3991365A (en) * | 1974-10-31 | 1976-11-09 | Hewlett-Packard Company | Instantaneous frequency measurement system |
| CN201859177U (en) * | 2010-09-29 | 2011-06-08 | 南京安能电气控制设备有限公司 | Measurement module for low-frequency alternating current signal in relay protection device |
| CN103913659A (en) * | 2014-03-30 | 2014-07-09 | 河北工业大学 | Instantaneous protection tester and operation method thereof |
| CN204241562U (en) * | 2014-11-19 | 2015-04-01 | 瓮福（集团）有限责任公司 | A kind of frequency detection circuit based on LPC2132 microcontroller |
| CN209624682U (en) * | 2019-01-18 | 2019-11-12 | 华能瑞金发电有限责任公司 | A kind of electric system primary frequency control system frequency measuring device |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114578114A (en) * | 2022-02-28 | 2022-06-03 | 特变电工西安电气科技有限公司 | SVG power module bypass state detection circuit |
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| CN112269056B (en) | 2024-04-12 |
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