CN218068139U - Power grid frequency detection circuit and device - Google Patents
Power grid frequency detection circuit and device Download PDFInfo
- Publication number
- CN218068139U CN218068139U CN202221984848.9U CN202221984848U CN218068139U CN 218068139 U CN218068139 U CN 218068139U CN 202221984848 U CN202221984848 U CN 202221984848U CN 218068139 U CN218068139 U CN 218068139U
- Authority
- CN
- China
- Prior art keywords
- sampling circuit
- resistor
- frequency
- operational amplifier
- inverting input
- 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
Images
Landscapes
- Measurement Of Current Or Voltage (AREA)
Abstract
The utility model provides a grid frequency detection circuitry and device belongs to grid frequency detection area, include: the first end of the voltage sampling circuit is connected with the positive end of a power grid through a first resistance network, and the second end of the voltage sampling circuit is connected with the negative end of the power grid through a second resistance network; the first end of the frequency sampling circuit is connected with the output end of the voltage sampling circuit, and the second end of the frequency sampling circuit is connected with a reference voltage; and the DSP processor is connected with the voltage sampling circuit and the output end of the frequency sampling circuit through a filter circuit. Has the advantages that: the utility model discloses frequency sampling circuit is on voltage sampling circuit's basis, further with the square wave signal that reference voltage comparison obtained, eliminates because of the sampling precision deviation that the reference voltage biasing leads to, and then has improved frequency sampling precision.
Description
Technical Field
The utility model relates to a power grid frequency detection area especially relates to a power grid frequency detection circuitry and device.
Background
In recent years, due to the wide application of a large number of grid-connected inverter devices and energy storage converters, the current, the voltage and the grid frequency in a power grid are changed, so that the power quality is seriously reduced, and the power quality of the power grid and the operation efficiency of equipment are directly influenced by the detection precision of the grid frequency. The instability of the grid frequency will affect the normal operation of some precision equipment and instruments. Thus, the grid frequency is detected.
The existing frequency detection circuit only provides for detecting the power grid frequency, because of the difference of hardware circuits and power grid interference, the periods of each square wave of the circuit in practical application are different, even in places with serious power grid harmonics, a plurality of high-frequency square waves can appear at zero crossing points, when a filter capacitor is added to be overlarge, phase delay can be caused, a series of problems such as inconvenience in control and idle work can be caused, and the corresponding power grid frequency detection precision can be correspondingly deteriorated.
Disclosure of Invention
In order to solve the technical problem, the utility model provides a grid frequency detection circuit and device.
The utility model solves the technical problem that the following technical scheme can be adopted to realize:
a grid frequency detection circuit, comprising:
the voltage sampling circuit is characterized in that a first end of the voltage sampling circuit is connected with the positive end of a power grid through a first resistance network, and a second end of the voltage sampling circuit is connected with the negative end of the power grid through a second resistance network;
the first end of the frequency sampling circuit is connected with the output end of the voltage sampling circuit, and the second end of the frequency sampling circuit is connected with a reference voltage;
and the DSP processor is connected with the voltage sampling circuit and the output end of the frequency sampling circuit through a filter circuit.
Preferably, the voltage sampling circuit includes:
the inverting input end of the first operational amplifier is connected with the positive end of the power grid through a first resistor, the non-inverting input end of the first operational amplifier is connected with the negative end of the power grid through a second resistor, and the non-inverting input end and the inverting input end of the first operational amplifier are respectively connected with the ground end through a third resistor;
and the first capacitor and the fourth resistor are connected in parallel between the inverting input end and the output end of the first operational amplifier.
Preferably, the first resistor comprises a plurality of resistors, and the plurality of resistors are connected in series to form the first resistor network.
Preferably, the second resistor comprises a plurality of second resistors, and the plurality of second resistors are connected in series to form the second resistor network.
Preferably, the voltage sampling circuit further includes: and the second capacitor and the fifth resistor are connected in parallel between the non-inverting input end of the first operational amplifier and the grounding end.
Preferably, the frequency sampling circuit includes:
the inverting input end of the second operational amplifier is connected with the output end of the voltage sampling circuit through a sixth resistor, the non-inverting input end of the second operational amplifier is connected with the reference voltage through a seventh resistor, and the non-inverting input end and the inverting input end of the second operational amplifier are respectively connected with the ground end through a third capacitor;
and the eighth resistor is connected between the inverting input end and the output end of the second operational amplifier in parallel.
Preferably, the frequency sampling circuit further includes:
and the ninth resistor is connected between the output end of the second operational amplifier and a power supply end.
Preferably, the filter circuit includes: one end of the tenth resistor is connected with the output end of the second operational amplifier, and the other end of the tenth resistor is connected with the DSP processor and the grounding end through a fourth capacitor.
Preferably, the cut-off frequency of the filter circuit is set to 5KHz to 15KHz.
The utility model also provides a grid frequency detection device, include as above-mentioned grid frequency detection circuitry.
The utility model discloses technical scheme's advantage or beneficial effect lie in:
the utility model discloses frequency detection circuit is on voltage sampling circuit's basis, further with the square wave signal that reference voltage comparison obtained, eliminates the sampling precision deviation that leads to because of the reference voltage biasing.
Drawings
Fig. 1 is a schematic structural diagram of a power grid frequency detection circuit according to a preferred embodiment of the present invention;
fig. 2 is a schematic circuit diagram of a voltage sampling circuit according to a preferred embodiment of the present invention;
fig. 3 is a circuit diagram of a frequency sampling circuit according to a preferred embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.
It should be noted that, in the case of no conflict, the embodiments and features of the embodiments of the present invention may be combined with each other.
The present invention will be further described with reference to the accompanying drawings and specific embodiments, which are not intended to limit the present invention.
The present invention provides a power grid frequency detection circuit based on the above problems in the prior art, which belongs to the field of power grid frequency detection, as shown in fig. 1-3, including:
the voltage sampling circuit 1 is characterized in that a first end of the voltage sampling circuit 1 is connected with the positive end of a power grid through a first resistance network, and a second end of the voltage sampling circuit 1 is connected with the negative end of the power grid through a second resistance network;
the first end of the frequency sampling circuit 2 is connected with the output end of the voltage sampling circuit 1, and the second end of the frequency sampling circuit 2 is connected with a reference voltage;
and the DSP processor 3 is connected with the voltage sampling circuit 1 and the output end of the frequency sampling circuit 2 through a filter circuit.
Specifically, a voltage sampling circuit 1 is used for sampling a power grid to obtain a power grid voltage sampling signal, and then a frequency sampling circuit 2 is used for further comparing the voltage sampling signal with a reference voltage to obtain a square wave signal which is used as a frequency sampling signal on the basis of voltage sampling to eliminate sampling precision deviation caused by reference voltage offset; after receiving the frequency sampling signals for a certain number of times, the DSP processor 3 processes the acquired frequency sampling signals to obtain an average frequency.
Specifically, the embodiment of the utility model provides an adopt the mode of moving average filtering, real-time output frequency sampled signal data, frequency sampled signal once every gathering, and two frequency sampled signal before are average, then export a frequency sample value. For example, averaging the frequency sampling signal acquired for the third time with the frequency sampling signals acquired for the first time and the second time to output a frequency sampling value; and then, averaging the frequency sampling signal acquired for the fourth time and the frequency sampling signals acquired for the second time and the third time to output a frequency sampling value, and realizing the detection of the power grid frequency according to the rule.
Further, the embodiment of the utility model provides a realize cubic moving average filtering through the DSP treater, if be less than 3 times, then the filtering precision can not reach 0.01Hz, if exceed 3 times, then can influence the overfrequency protection and the under-frequency protection time of dc-to-ac converter.
As a preferred embodiment, among others, as shown in fig. 2, the voltage sampling circuit 1 includes:
the inverting input end of the first operational amplifier U1A is connected with the positive end GRID _ R of the power GRID through a first resistor, the non-inverting input end of the first operational amplifier U1A is connected with the negative end GRID _ N of the power GRID through a second resistor, and the non-inverting input end and the inverting input end of the first operational amplifier U1A are respectively connected with the grounding end through a third resistor;
the first capacitor C1 and the fourth resistor R4 are connected in parallel between the inverting input terminal and the output terminal of the first operational amplifier U1A.
In a preferred embodiment, the first resistor includes a plurality of first resistors, and the plurality of first resistors are connected in series to form a first resistor network.
In particular, the first resistors may include 8, such as R11 and R12.. R18 in fig. 2, and 8 first resistors form the first resistor network.
In a preferred embodiment, the second resistor includes a plurality of second resistors, and the plurality of second resistors are connected in series to form the second resistor network.
Specifically, the second resistors may include 8, such as R21 and R22.. R28 in fig. 2, and the 8 second resistors form the second resistor network.
As a preferred embodiment, among others, the voltage sampling circuit 1 further includes: the second capacitor C2 and the fifth resistor R5 are connected in parallel between the non-inverting input terminal and the ground terminal of the first operational amplifier U1A.
As a preferred embodiment, among others, as shown in fig. 3, the frequency sampling circuit 2 includes:
the inverting input end of the second operational amplifier U1B is connected with the output end of the voltage sampling circuit 1 through a sixth resistor R6, the non-inverting input end of the second operational amplifier U1B is connected with the reference voltage through a seventh resistor R7, and the non-inverting input end and the inverting input end of the second operational amplifier U1B are respectively connected with the grounding end through a third capacitor C3;
and the eighth resistor R8 is connected between the inverting input end and the output end of the second operational amplifier U1B in parallel.
As a preferred embodiment, the frequency sampling circuit 2 further includes:
the ninth resistor R9 is connected between the output terminal of the second operational amplifier U1B and a power supply terminal, wherein the power supply terminal is used for providing + 3.3V.
As a preferred embodiment, among others, the filter circuit includes: one end of the tenth resistor R10 is connected to the output end of the second operational amplifier U1B, and the other end of the tenth resistor R10 is connected to the DSP processor 3 and to the ground through a fourth capacitor C4.
Specifically, in this embodiment, filtering is performed by the fourth capacitor C4, and voltage division is performed by the tenth resistor R10.
In a preferred embodiment, the cut-off frequency of the filter circuit is set to 5KHz to 15KHz.
Specifically, the utility model discloses carried out the filtering in the sampling phase, the filter cutoff frequency sets up about 10KHz 5KHz, gets its average value after through filtering and cubic sampling for frequency sampling precision improves to 0.01Hz, and then reduces the idle of the external output of dc-to-ac converter, improves the electric energy quality who contains this method dc-to-ac converter and PCS device electric wire netting.
Furthermore, the DSP can also count the frequency sampling signals output by the frequency sampling circuit, and the DSP processes the acquired frequency sampling signals to obtain average frequency after receiving the frequency sampling signals for a certain number of times. Preferably, the preset times are 3 times, the DSP processor receives square waves acquired by the frequency sampling circuit in three continuous power frequency periods, the frequency sampling signals are square waves, the three acquired frequency sampling signals are processed to obtain average frequency, and the frequency sampling precision is improved to reach 0.01Hz.
It should be noted that the accuracy is reduced by the form of a single circuit or by filtering alone, and the disadvantage of acquiring the frequency sampling signal more than three times is that: the response speed may become slow, and under the condition that the power grid frequency is abnormal, the system or the inverter may not respond to the change of the corresponding frequency in time.
The utility model also provides a grid frequency detection device, include as above-mentioned grid frequency detection circuitry.
Adopt above-mentioned technical scheme to have following advantage or beneficial effect: the utility model discloses frequency sampling circuit is on voltage sampling circuit's basis, further with the square wave signal that reference voltage comparison obtained, eliminates the sampling precision deviation that leads to because of the reference voltage biasing.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope and the embodiments of the present invention, and it should be appreciated by those skilled in the art that the equivalent and obvious modifications made in the description and the drawings should be included within the scope of the present invention.
Claims (10)
1. A grid frequency detection circuit, comprising:
the voltage sampling circuit is characterized in that a first end of the voltage sampling circuit is connected with the positive end of a power grid through a first resistance network, and a second end of the voltage sampling circuit is connected with the negative end of the power grid through a second resistance network;
the first end of the frequency sampling circuit is connected with the output end of the voltage sampling circuit, and the second end of the frequency sampling circuit is connected with a reference voltage;
and the DSP processor is connected with the voltage sampling circuit and the output end of the frequency sampling circuit through a filter circuit.
2. The grid frequency detection circuit according to claim 1, wherein the voltage sampling circuit comprises:
the inverting input end of the first operational amplifier is connected with the positive end of the power grid through a first resistor, the non-inverting input end of the first operational amplifier is connected with the negative end of the power grid through a second resistor, and the non-inverting input end and the inverting input end of the first operational amplifier are respectively connected with the ground end through a third resistor;
and the first capacitor and the fourth resistor are connected in parallel between the inverting input end and the output end of the first operational amplifier.
3. The grid frequency detection circuit according to claim 2, wherein the first resistor comprises a plurality of first resistors connected in series to form the first resistor network.
4. The grid frequency detection circuit according to claim 2, wherein the second resistor comprises a plurality of second resistors, and the plurality of second resistors are connected in series to form the second resistor network.
5. The grid frequency detection circuit according to claim 2, wherein the voltage sampling circuit further comprises: and the second capacitor and the fifth resistor are connected in parallel between the non-inverting input end of the first operational amplifier and the grounding end.
6. The grid frequency detection circuit according to claim 1, wherein the frequency sampling circuit comprises:
the inverting input end of the second operational amplifier is connected with the output end of the voltage sampling circuit through a sixth resistor, the non-inverting input end of the second operational amplifier is connected with the reference voltage through a seventh resistor, and the non-inverting input end and the inverting input end of the second operational amplifier are respectively connected with a grounding end through a third capacitor;
and the eighth resistor is connected between the inverting input end and the output end of the second operational amplifier in parallel.
7. The grid frequency detection circuit according to claim 6, wherein the frequency sampling circuit further comprises:
and the ninth resistor is connected between the output end of the second operational amplifier and a power supply end.
8. The grid frequency detection circuit according to claim 6, wherein the filter circuit comprises: one end of the tenth resistor is connected with the output end of the second operational amplifier, and the other end of the tenth resistor is connected with the DSP processor and the grounding end through a fourth capacitor.
9. The grid frequency detection circuit according to claim 1, wherein a cutoff frequency of the filter circuit is set to 5KHz to 15KHz.
10. A grid frequency detection device comprising a grid frequency detection circuit according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221984848.9U CN218068139U (en) | 2022-07-29 | 2022-07-29 | Power grid frequency detection circuit and device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221984848.9U CN218068139U (en) | 2022-07-29 | 2022-07-29 | Power grid frequency detection circuit and device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN218068139U true CN218068139U (en) | 2022-12-16 |
Family
ID=84402780
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202221984848.9U Active CN218068139U (en) | 2022-07-29 | 2022-07-29 | Power grid frequency detection circuit and device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN218068139U (en) |
-
2022
- 2022-07-29 CN CN202221984848.9U patent/CN218068139U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106124844B (en) | A kind of direct current bus voltage detecting circuit | |
| CN207198238U (en) | Power grid frequency detection circuit | |
| CN108089092B (en) | Generator rotor winding leakage detection device | |
| CN110967607A (en) | Insulation detection circuit, method and battery management system | |
| CN103197130A (en) | Power grid voltage ZCP (Zero Crossing Point) detecting method and device | |
| CN211785733U (en) | Three-phase multifunctional metering system | |
| CN110618338B (en) | Electric energy quality transient measurement method, device and equipment | |
| CN108414838A (en) | A kind of inverter parallel system line impedance measurement method | |
| CN108872697A (en) | High interference immunity voltage collection circuit and its method for power battery monomer | |
| CN218068139U (en) | Power grid frequency detection circuit and device | |
| CN205120856U (en) | Power quality monitor device of transformer substation | |
| CN205861836U (en) | The voltage dip synchronous monitoring system of multistage power grid | |
| CN105024734A (en) | Electricity utilization information acquisition system interference signal suppression method and system thereof | |
| WO2023221881A1 (en) | Adaptive suppression method and system for flexible direct-current high-frequency resonance | |
| CN210514514U (en) | Small signal acquisition circuit applied to power distribution terminal | |
| CN204859178U (en) | System for restrain power consumption information collection system interfering signal | |
| CN209946250U (en) | Three-phase current acquisition circuit based on compensation circuit and acquisition device | |
| CN103364672B (en) | The condition monitoring system of magnet controlled reactor type dynamic reactive compensation device and method | |
| CN210835177U (en) | Battery detection circuit | |
| CN210347815U (en) | Photovoltaic harmonic monitoring device based on electric energy metering chip | |
| CN107046271A (en) | A kind of low-pass digital filter method suitable for DC line protection | |
| CN202929190U (en) | Relay protection tester inspection device | |
| CN207396596U (en) | Non-isolated multichannel three-phase mains voltage detection circuit | |
| CN200989920Y (en) | Electric energy quality tester signal dispensable circuit | |
| CN219287146U (en) | Dynamometer resonance suppression device and dynamometer system based on C-type filter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |