CN114755546A - Method and device for detecting direct-current fault arc of photovoltaic system and photovoltaic system - Google Patents
Method and device for detecting direct-current fault arc of photovoltaic system and photovoltaic system Download PDFInfo
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Abstract
The invention provides a method and a device for detecting a direct-current fault arc of a photovoltaic system and the photovoltaic system. The invention discloses a method for detecting a direct-current fault arc of a photovoltaic system, which comprises the following steps: acquiring PV current and PV instantaneous power of a direct current side of a photovoltaic system; when the change rate of the PV current is larger than a preset current threshold value, determining the current mutation level of the PV current; when the change rate of the PV instantaneous power is larger than a preset power threshold value, determining a power abrupt change level of the PV instantaneous power; if the change rate of the PV current is greater than the preset current threshold and the change rate of the PV instantaneous power is greater than the preset power threshold, determining a fault arc grade according to the current mutation grade and the power mutation grade, performing corresponding arc extinguishing judgment according to the fault arc grade, and judging whether a fault arc occurs according to an arc extinguishing judgment result. The accuracy of arc detection is improved, and the method is simple, reliable, high in accuracy and low in cost.
Description
Technical Field
The invention relates to the technical field of power electronic control, in particular to a method and a device for detecting a direct-current fault arc of a photovoltaic system and the photovoltaic system.
Background
With the widespread domestic application of photovoltaic power generation technology, the safety problem of photovoltaic systems is also concerned. For example, electric shock and fire risk from arc faults: because the sunshine continuously shines and makes the electric arc in the photovoltaic system return circuit constantly absorb energy, if not extinguish electric arc in time, will lead to electric arc burning to evolve into the circuit conflagration, continuous flame high temperature will seriously damage photovoltaic module, collection flow box and electric wire etc..
The existing arc detection method such as fast Fourier transform judges whether a fault arc occurs through spectrum analysis, and the algorithm is complex and depends on the quality of the arc, so that detection errors are easily caused.
Disclosure of Invention
The problem solved by the invention is how to improve the accuracy of arc detection.
In order to solve the above problem, the present invention provides a method for detecting a dc fault arc in a photovoltaic system, including: acquiring PV current and PV instantaneous power at the direct current side of a photovoltaic system; when the change rate of the PV current is larger than a preset current threshold value, determining the current mutation level of the PV current; when the change rate of the PV instantaneous power is larger than a preset power threshold value, determining a power abrupt change level of the PV instantaneous power; if the change rate of the PV current is larger than the preset current threshold and the change rate of the PV instantaneous power is larger than the preset power threshold, determining the fault arc grade according to the current mutation grade and the power mutation grade, performing corresponding arc extinguishing judgment according to the fault arc grade, and judging whether the fault arc occurs according to the arc extinguishing judgment result.
According to the method for detecting the direct-current fault arc of the photovoltaic system, when the change rate of the PV current is larger than the preset current threshold and the change rate of the PV instantaneous power is larger than the preset power threshold, the fault arc grade is determined according to the current mutation grade and the power mutation grade, and corresponding arc extinction judgment is carried out according to the fault arc grade, so that the accuracy of arc detection is improved.
Optionally, the preset current threshold is 0.1A/5ms, and the determining the current abrupt change level of the PV current when the rate of change of the PV current is greater than the preset current threshold includes: when the change rate of the PV current is more than 0.1A/5ms and less than 0.2A/5ms, determining that the current mutation grade is first grade; when the change rate of the PV current is more than 0.2A/5ms and less than 0.3A/5ms, determining the current mutation grade as two grades; and when the change rate of the PV current is more than 0.3A/5ms, determining the current mutation grade to be three grades.
The method for detecting the direct-current fault arc of the photovoltaic system is beneficial to determining the accurate fault arc grade by dividing the current mutation grade, so that the accuracy of arc detection is improved.
Optionally, the preset power threshold is 60w/5ms, and the determining the power abrupt change level of the PV instantaneous power when the rate of change of the PV instantaneous power is greater than the preset power threshold includes: when the change rate of the PV instantaneous power is more than 60w/5ms and less than 80w/5ms, determining the power abrupt change level as one level; when the change rate of the PV instantaneous power is more than 80w/5ms and less than 100w/5ms, determining the power abrupt change level as two levels; determining the power abrupt change level to be three levels when the rate of change of the PV instantaneous power is greater than 100w/5ms and less than 200w/5 ms.
According to the method for detecting the direct-current fault arc of the photovoltaic system, the power abrupt change grade is divided, so that the accurate fault arc grade can be determined, and the accuracy of arc detection is improved.
Optionally, the determining a fault arc level according to the current jump level and the power jump level comprises: if the current mutation grade is one grade and the power mutation grade is one grade, determining that the fault arc grade is one grade; if the current mutation grade is first grade and the power mutation grade is second grade, determining that the fault arc grade is second grade; if the current mutation grade is one grade and the power mutation grade is three grades, determining that the fault arc grade is three grades; if the current mutation grade is two grades and the power mutation grade is one grade, determining that the fault arc grade is two grades; if the current mutation grade is two grades and the power mutation grade is two grades, determining that the fault arc grade is three grades; if the current mutation level is two levels and the power mutation level is three levels, determining that the fault arc level is four levels; if the current mutation level is three levels and the power mutation level is one level, determining that the fault arc level is three levels; if the current mutation level is three levels and the power mutation level is two levels, determining that the fault arc level is four levels; and if the current mutation grade is three grades and the power mutation grade is three grades, determining that the fault arc grade is five grades.
According to the method for detecting the direct-current fault arc of the photovoltaic system, different fault arc grades are determined according to the current mutation grade and the power mutation grade, so that the accuracy of arc detection is improved.
Optionally, the performing, according to the fault arc class, the corresponding arc extinguishing judgment includes: when the fault arc level is one level, limiting the direct current power to zero, and recovering to normal after the direct current power lasts for 2 s; when the fault arc level is two-stage, limiting the direct current power to zero, and recovering to normal after the direct current power lasts for 3 s; when the fault arc level is three-level, limiting the direct current power to zero, and recovering to normal after the direct current power lasts for 4 s; when the fault arc level is four, limiting the direct current power to zero, and recovering to normal after the direct current power lasts for 5 s; and when the fault arc level is five, limiting the direct current power to zero, and recovering to be normal after the direct current power lasts for 6 s.
According to the method for detecting the direct-current fault arc of the photovoltaic system, the direct-current power is limited to zero for different time and then is recovered to be normal by setting different fault arc grades, so that the accuracy of fault arc detection is ensured, and the influence on the normal work of the photovoltaic system caused by overlong load limitation is prevented.
Optionally, the determining whether a fault arc occurs according to the arc extinguishing determination result includes: if the PV current is smaller than a preset fault threshold value after the PV current is recovered to be normal, judging that the fault electric arc occurs; and if the PV current is greater than or equal to the preset fault threshold value after the PV current is recovered to be normal, determining that the arc extinction judgment is false alarm, and adjusting the preset current threshold value and the preset power threshold value when the false alarm times meet the preset times threshold value.
According to the method for detecting the direct-current fault arc of the photovoltaic system, when the arc extinction judgment misstatement meets the preset frequency threshold, the preset current threshold and the preset power threshold are adjusted, so that the generation of the misstatement is reduced, and the accuracy of arc detection is improved.
Optionally, after it is determined that the arc extinction determination is a false alarm, the method for detecting the dc fault arc of the photovoltaic system further includes: determining a frequent period and an idle period of the false alarm according to the time period of the false alarm; in the frequent period, the preset current threshold and the preset power threshold are increased; and in the idle period, reducing the preset current threshold and the preset power threshold.
The method for detecting the direct-current fault arc of the photovoltaic system adjusts the preset current threshold value and the preset power threshold value adaptively according to the frequent period and the idle period of the false alarm, thereby reducing the generation of the false alarm and improving the accuracy of arc detection.
Optionally, the obtaining PV current and PV instantaneous power at the dc side of the photovoltaic system includes: and sampling the PV current and the PV voltage in real time according to a preset frequency, and calculating the PV instantaneous power at different moments according to the sampled PV current and PV voltage.
The method for detecting the direct-current fault arc of the photovoltaic system comprises the steps of sampling the PV current and the PV voltage in real time according to the preset frequency, calculating the PV instantaneous power at different moments according to the PV current and the PV voltage, and determining the grade of the fault arc according to the current mutation grade and the power mutation grade.
The invention also provides a detection device for the direct-current fault arc of the photovoltaic system, which comprises: the acquisition module is used for acquiring PV current and PV instantaneous power at the direct current side of the photovoltaic system; a grade module for determining a current sudden change grade of the PV current when the change rate of the PV current is greater than a preset current threshold value, and determining a power sudden change grade of the PV instantaneous power when the change rate of the PV instantaneous power is greater than a preset power threshold value; and the judging module is used for determining the fault arc grade according to the current sudden change grade and the power sudden change grade if the change rate of the PV current is greater than the preset current threshold and the change rate of the PV instantaneous power is greater than the preset power threshold, performing corresponding arc extinguishing judgment according to the fault arc grade, and judging whether the fault arc occurs according to the arc extinguishing judgment result. Compared with the prior art, the detection device for the photovoltaic system direct-current fault arc and the detection method for the photovoltaic system direct-current fault arc have the same advantages, and are not described again.
The invention also provides a photovoltaic system, which comprises a detection device for the direct-current fault arc of the photovoltaic system. Compared with the prior art, the photovoltaic system and the detection device for the direct-current fault arc of the photovoltaic system have the same advantages, and are not described again.
Drawings
Fig. 1 is a schematic diagram of a method for detecting a dc fault arc in a photovoltaic system according to an embodiment of the present invention.
Detailed Description
In the existing arc detection method, the FFT mainly analyzes the low frequency band, and when the FFT analyzes the spectrum analysis, there are errors in four aspects: (1) aliasing the frequency spectrum; (2) a fence effect; (3) frequency spectrum leakage; (4) inter-spectral interference. The frequency spectrum leakage refers to the mutual influence among spectral lines in a signal frequency spectrum, so that a measurement result deviates from an actual value, and meanwhile, some false spectrums with smaller amplitude appear at other frequency points on two sides of the spectral lines, so that the frequency spectrum leakage is caused because the sampling frequency and the signal frequency are asynchronous, and the phase of a periodic sampling signal is discontinuous at the initial end and the terminal end. The spectrum leakage problem easily causes detection errors, and finally causes arc detection errors.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
As shown in fig. 1, an embodiment of the present invention provides a method for detecting a dc fault arc in a photovoltaic system, including: acquiring PV current and PV instantaneous power at the direct current side of a photovoltaic system; when the change rate of the PV current is larger than a preset current threshold value, determining the current mutation level of the PV current; when the change rate of the PV instantaneous power is larger than a preset power threshold value, determining a power abrupt change level of the PV instantaneous power; if the change rate of the PV current is larger than the preset current threshold and the change rate of the PV instantaneous power is larger than the preset power threshold, determining the fault arc grade according to the current mutation grade and the power mutation grade, performing corresponding arc extinguishing judgment according to the fault arc grade, and judging whether the fault arc occurs according to the arc extinguishing judgment result.
Specifically, in this embodiment, the method for detecting a dc fault arc in a photovoltaic system includes: the method includes the steps that Photovoltaic (Photovoltaic) current and PV instantaneous Power of a direct current side of a Photovoltaic system are obtained, due to the fact that Tracking of a Photovoltaic panel and MPPT (Maximum Power Point Tracking) is changed slowly in a normal working state, large transient change of the PV Power and the PV current cannot occur, but large transient sudden change of the PV Power and the PV current can occur due to the fact that abnormal arcs occur, a fault arc state can be identified by detecting the change of the PV Power and the PV current, fault arc states corresponding to different changing rates of the PV Power and the PV current are different, and in order to improve accuracy of arc detection, sudden change conditions of the PV current and the PV instantaneous Power need to be determined accurately.
And when the change rate of the PV current is greater than a preset current threshold, determining the current abrupt change level of the PV current, and when the change rate of the PV instantaneous power is greater than a preset power threshold, determining the power abrupt change level of the PV instantaneous power. When the change rate of the PV current is greater than the preset current threshold and the change rate of the PV instantaneous power is greater than the preset power threshold, the current sudden change and the power sudden change both meet the preset arc condition, which indicates that the fault arc occurs with a high probability, the arc extinction judgment needs to be carried out, and whether the fault arc occurs is judged according to the arc extinction judgment result.
However, the fault arc states are different under various conditions, and arc extinguishing operations are also different, so that the fault arc grade needs to be determined according to the current mutation grade and the power mutation grade, and corresponding arc extinguishing judgment is performed according to the fault arc grade to improve the accuracy of arc detection.
Taking the application to a photovoltaic inverter as an example, the photovoltaic inverter converts direct current provided by the solar module into alternating current for civil use or industrial use, and can be used for charging electric automobiles and the like. When the degree of accuracy that detects the electric arc obtained improving, can provide more stable power for electric automobile's equipment such as electric pile that fills.
In this embodiment, when the change rate of the PV current is greater than the preset current threshold and the change rate of the PV instantaneous power is greater than the preset power threshold, the fault arc level is determined according to the current sudden change level and the power sudden change level, and corresponding arc extinction judgment is performed according to the fault arc level, so that the accuracy of arc detection is improved.
Optionally, the preset current threshold is 0.1A/5ms, and when the rate of change of the PV current is greater than the preset current threshold, determining the current jump level of the PV current includes: when the change rate of the PV current is more than 0.1A/5ms and less than 0.2A/5ms, determining that the current mutation grade is first grade; when the change rate of the PV current is more than 0.2A/5ms and less than 0.3A/5ms, determining the current mutation grade as two grades; when the change rate of the PV current is more than 0.3A/5ms, determining the current mutation grade as three grades.
Specifically, in the present embodiment, the preset current threshold is 0.1A/5ms, and when the change rate of the PV current is greater than 0.1A/5ms, the current jump level of the PV current is determined and divided into a first level, a second level and a third level, where the change rate of the first level, i.e., the PV current, is greater than 0.1A/5ms and less than 0.2A/5ms, the change rate of the second level, i.e., the PV current, is greater than 0.2A/5ms and less than 0.3A/5ms, and the change rate of the third level, i.e., the PV current, is greater than 0.3A/5 ms. Different current abrupt change grades are divided to be beneficial to determining accurate fault arc grades, so that the accuracy of arc detection is improved.
The time period of 5ms is only a preferred setting and can be adjusted according to actual conditions.
In the embodiment, the current abrupt change grade is divided, so that the accurate fault arc grade is determined, and the accuracy of arc detection is improved.
Optionally, the preset power threshold is 60w/5ms, and when the rate of change of the PV instantaneous power is greater than the preset power threshold, the determining the power abrupt change level of the PV instantaneous power includes: when the change rate of the PV instantaneous power is more than 60w/5ms and less than 80w/5ms, determining the power abrupt change level as one level; when the change rate of the PV instantaneous power is more than 80w/5ms and less than 100w/5ms, determining the power abrupt change level as two levels; determining the power ramp level to be three levels when the rate of change of the PV instantaneous power is greater than 100w/5ms and less than 200w/5 ms.
Specifically, in the present embodiment, the preset power threshold is 60w/5ms, and when the PV instantaneous power change rate is greater than 60w/5ms, the power abrupt change level of the PV instantaneous power is determined and divided into a first level, a second level and a third level, where the first level, i.e., the PV instantaneous power change rate, is greater than 60w/5ms and less than 80w/5ms, the second level, i.e., the PV instantaneous power change rate, is greater than 80w/5ms and less than 100w/5ms, and the third level, i.e., the PV instantaneous power change rate, is greater than 100w/5ms and less than 200w/5 ms. Different power abrupt change grades are beneficial to determining accurate fault arc grades, so that the accuracy of arc detection is improved.
In the embodiment, the power abrupt change grade is divided, so that the accurate fault arc grade is determined, and the accuracy of arc detection is improved.
Optionally, the determining a fault arc level according to the current sudden change level and the power sudden change level includes: if the current mutation grade is one grade and the power mutation grade is one grade, determining that the fault arc grade is one grade; if the current mutation grade is first grade and the power mutation grade is second grade, determining that the fault arc grade is second grade; if the current mutation grade is one grade and the power mutation grade is three grades, determining that the fault arc grade is three grades; if the current mutation grade is two grades and the power mutation grade is one grade, determining that the fault arc grade is two grades; if the current mutation grade is two grades and the power mutation grade is two grades, determining that the fault arc grade is three grades; if the current mutation level is two levels and the power mutation level is three levels, determining that the fault arc level is four levels; if the current mutation level is three levels and the power mutation level is one level, determining that the fault arc level is three levels; if the current mutation level is three levels and the power mutation level is two levels, determining that the fault arc level is four levels; and if the current mutation grade is three grades and the power mutation grade is three grades, determining that the fault arc grade is five grades.
Specifically, in the present embodiment, different fault arc levels are determined according to the current sudden change level and the power sudden change level with reference to the fault arc level comparison table shown in table one. For example, when the current sudden change level is one level and the power sudden change level is one level, the corresponding fault arc level is one level, and when the current sudden change level is three levels and the power sudden change level is three levels, the corresponding fault arc level is five levels.
Electric arc grade comparison table for fault
| First order power ramp | Second order power ramp | Three stage power ramp | |
| Sudden change of primary current | First order fault arc | Second order fault arc | Three-stage fault arc |
| Second order current jump | Second order fault arc | Three-stage fault arc | Four-stage fault arc |
| Three-stage current jump | Three-stage fault arc | Four-stage fault arc | Five-stage fault arc |
In the present embodiment, different fault arc levels are determined according to the current sudden change level and the power sudden change level, thereby improving the accuracy of arc detection.
Optionally, the performing, according to the fault arc class, a corresponding arc extinction judgment includes: when the fault arc level is one level, limiting the direct current power to zero, and recovering to normal after the direct current power lasts for 2 s; when the fault arc level is two-stage, limiting the direct current power to zero, and recovering to normal after the direct current power lasts for 3 s; when the fault arc level is three-level, limiting the direct current power to zero, and recovering to normal after the direct current power lasts for 4 s; when the fault arc level is four, limiting the direct current power to zero, and recovering to normal after the direct current power lasts for 5 s; and when the fault arc level is five, limiting the direct current power to zero, and recovering to be normal after the direct current power lasts for 6 s.
Specifically, in this embodiment, because the energy intensities of the arcs are different at different fault arc levels, when the fault arc level is one level, the dc power is limited to zero and returns to normal after being continued for 2 seconds, and because the dc power is limited to zero and is continued for 2 seconds, the arc is completely dead and goes out when losing energy source naturally; and when the fault arc level is five, only the direct current power is limited to zero for 2s, and the arc can not be completely guaranteed to be extinguished, so that the fault arc can be recovered to be normal after lasting for 6s, but the time can not be prolonged, so that the normal work of the photovoltaic system is prevented from being influenced due to the long-term load limitation.
The scheme preferentially adopts a mode of limiting the power of the direct current side, only controls one path of direct current to limit the load to zero, does not change the integral output power to zero, and reduces the loss of generated energy and the power fluctuation; in the method for limiting the ac side power, which dc side limiting power is not specified, so that the output power is limited to zero as a whole, which has the problems of large power fluctuation, power generation loss and the like.
In this embodiment, through setting up under the different fault arc grades, carry the limit load with direct current power to zero and resume normal after lasting different time, both guaranteed fault arc detection's accuracy, prevent simultaneously that the limit load of overlength leads to photovoltaic system normal work to receive the influence.
Optionally, the determining whether a fault arc occurs according to the arc extinguishing determination result includes: if the PV current is smaller than a preset fault threshold value after the PV current is recovered to be normal, judging that the fault electric arc occurs; and if the PV current is greater than or equal to the preset fault threshold value after the PV current is recovered to be normal, determining that the arc extinction judgment is false alarm, and adjusting the preset current threshold value and the preset power threshold value when the false alarm times meet the preset times threshold value.
Specifically, in this embodiment, the power load limit is recovered to be normal, because there is no connection at the arc point, and the air cannot conduct electricity, the magnitude of the PV current and a preset fault threshold (for example, 1A, the actual current is far less than 1A when there is no current) at this time is determined, if the PV current is less than the preset fault threshold, it is indicated that a fault arc has occurred, a fault arc fault is reported, if the PV current is greater than or equal to the preset fault threshold, it is indicated that the change rate of the PV current and the change rate of the PV instantaneous power due to factors such as power disturbance meet a preset arc condition, at this time, the photovoltaic system continues to operate normally, and it is determined that this time of arc extinction determination is false alarm.
When the false alarm times meet a preset time threshold, adjusting the preset current threshold and the preset power threshold, for example, the preset time threshold is three times, and when the false alarm times reach three times within a certain time period, adjusting the preset current threshold from 0.1A/5ms to 0.2A/5ms, or adjusting the preset power threshold from 60w/5ms to 80w/5 ms. Therefore, arc extinguishing detection which is triggered at 0.15A/5ms and 70w/5ms before can not be triggered at a new preset current threshold and a new preset power threshold, so that the generation of false alarm is reduced, and the accuracy of arc detection is improved.
In this embodiment, when the arc extinction judges that the false alarm satisfies the preset number threshold, the preset current threshold and the preset power threshold are adjusted, so that the generation of false alarm is reduced, and the accuracy of arc detection is improved.
Optionally, after it is determined that the arc extinction determination is a false alarm, the method for detecting the dc fault arc of the photovoltaic system further includes: determining a frequent period and an idle period of the false alarm according to the time period of the false alarm; in the frequent period, the preset current threshold and the preset power threshold are increased; and in the idle period, reducing the preset current threshold and the preset power threshold.
Specifically, in the present embodiment, in the photovoltaic system, different time periods, for example, power disturbance, which have different peak periods and different valley periods, may cause an error in determining the fault arc, so that the preset current threshold and the preset power threshold need to be adaptively adjusted according to the time period in which the false alarm occurs. For example, in a power disturbance peak period, namely a frequent period in which false alarm occurs, the preset current threshold and the preset power threshold are increased, so that the change rate of the PV current and the change rate of the PV instantaneous power, which can be triggered under the original preset current threshold and the original preset power threshold, cannot be triggered under the new preset current threshold and the new preset power threshold, thereby reducing the generation of false alarm and improving the accuracy of arc detection. In a power disturbance valley period, namely an idle period in which false alarm occurs, the sensitivity of fault arc detection is improved by reducing the preset current threshold and the preset power threshold, for example, the preset current threshold is adjusted from 0.1A/5ms to 0.05A/5ms, and the preset power threshold is adjusted from 60w/5ms to 30w/5ms, so that the accuracy of arc detection is improved.
In this embodiment, the preset current threshold and the preset power threshold are adaptively adjusted according to the frequent period and the idle period in which false alarm occurs, so that the generation of false alarm is reduced, and the accuracy of arc detection is improved.
Optionally, the obtaining PV current and PV instantaneous power at the dc side of the photovoltaic system includes: and sampling the PV current and the PV voltage in real time according to a preset frequency, and calculating the PV instantaneous power at different moments according to the sampled PV current and PV voltage.
Specifically, in the present embodiment, when acquiring the PV current and the PV voltage on the dc side, the PV current and the PV voltage are sampled in real time according to a preset frequency, for example, sampling is performed at a switching period corresponding to 16kHz, and since the sampling frequency is very high, the PV instantaneous power at different times can be calculated according to the formula P = U × I according to the sampled PV current and PV voltage, and then the change rate of the PV instantaneous power can be determined.
The switching period refers to a time interval between a current update and a next update pulse of the PWM wave, and the update of the switching period requires a comparison between the modulated wave and the carrier wave, and is also referred to as a carrier period.
In the embodiment, after the PV current and the PV voltage are sampled in real time according to the preset frequency, the PV instantaneous power at different moments is calculated according to the PV current and the PV voltage, and then the fault arc level can be determined according to the current sudden change level and the power sudden change level.
Another embodiment of the present invention provides a device for detecting a dc fault arc in a photovoltaic system, including: the acquisition module is used for acquiring PV current and PV instantaneous power at the direct current side of the photovoltaic system; the grade module is used for determining the current sudden change grade of the PV current when the change rate of the PV current is greater than a preset current threshold value, and determining the power sudden change grade of the PV instantaneous power when the change rate of the PV instantaneous power is greater than a preset power threshold value; and the judging module is used for determining a fault arc grade according to the current mutation grade and the power mutation grade if the change rate of the PV current is greater than the preset current threshold and the change rate of the PV instantaneous power is greater than the preset power threshold, performing corresponding arc extinguishing judgment according to the fault arc grade, and judging whether a fault arc occurs according to an arc extinguishing judgment result.
Another embodiment of the invention provides a photovoltaic system, which includes a device for detecting a dc fault arc of the photovoltaic system.
Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present disclosure, and these changes and modifications are intended to be within the scope of the present disclosure.
Claims (10)
1. A method for detecting a direct-current fault arc of a photovoltaic system is characterized by comprising the following steps:
acquiring PV current and PV instantaneous power at the direct current side of a photovoltaic system;
when the change rate of the PV current is larger than a preset current threshold value, determining the current mutation level of the PV current;
when the change rate of the PV instantaneous power is larger than a preset power threshold value, determining a power abrupt change level of the PV instantaneous power;
if the change rate of the PV current is greater than the preset current threshold and the change rate of the PV instantaneous power is greater than the preset power threshold, determining a fault arc grade according to the current mutation grade and the power mutation grade, performing corresponding arc extinguishing judgment according to the fault arc grade, and judging whether a fault arc occurs according to an arc extinguishing judgment result.
2. The method according to claim 1, wherein the predetermined current threshold is 0.1A/5ms, and the determining the sudden current change level of the PV current when the PV current change rate is greater than the predetermined current threshold comprises:
when the change rate of the PV current is more than 0.1A/5ms and less than 0.2A/5ms, determining that the current mutation grade is first grade;
When the change rate of the PV current is more than 0.2A/5ms and less than 0.3A/5ms, determining the current mutation grade as two grades;
when the change rate of the PV current is more than 0.3A/5ms, determining the current mutation grade as three grades.
3. The method according to claim 2, wherein the predetermined power threshold is 60w/5ms, and the determining the sudden power change level of the PV instantaneous power when the rate of change of the PV instantaneous power is greater than the predetermined power threshold comprises:
when the change rate of the PV instantaneous power is more than 60w/5ms and less than 80w/5ms, determining the power abrupt change level as one level;
when the change rate of the PV instantaneous power is more than 80w/5ms and less than 100w/5ms, determining the power abrupt change level as two levels;
determining the power ramp level to be three levels when the rate of change of the PV instantaneous power is greater than 100w/5ms and less than 200w/5 ms.
4. The method according to claim 3, wherein the determining a fault arc level according to the sudden current change level and the sudden power change level comprises:
if the current mutation grade is one grade and the power mutation grade is one grade, determining that the fault arc grade is one grade;
If the current mutation grade is first grade and the power mutation grade is second grade, determining that the fault arc grade is second grade;
if the current mutation grade is one grade and the power mutation grade is three grades, determining that the fault arc grade is three grades;
if the current mutation grade is two grades and the power mutation grade is one grade, determining that the fault arc grade is two grades;
if the current mutation grade is two grades and the power mutation grade is two grades, determining that the fault arc grade is three grades;
if the current mutation level is two levels and the power mutation level is three levels, determining that the fault arc level is four levels;
if the current mutation level is three levels and the power mutation level is one level, determining that the fault arc level is three levels;
if the current mutation level is three levels and the power mutation level is two levels, determining that the fault arc level is four levels;
and if the current mutation grade is three grades and the power mutation grade is three grades, determining that the fault arc grade is five grades.
5. The method for detecting the dc fault arc of the photovoltaic system according to claim 4, wherein the determining to perform corresponding arc extinguishing according to the fault arc class includes:
When the fault arc level is one level, limiting the direct current power to zero, and recovering to normal after the direct current power lasts for 2 s;
when the fault arc level is two-level, limiting the direct current power to zero, and recovering to normal after the direct current power is continued for 3 s;
when the fault arc level is three-level, limiting the direct current power to zero, and recovering to normal after the direct current power is continuously maintained for 4 s;
when the fault arc level is four, limiting the direct current power to zero, and recovering to normal after the direct current power is continuously maintained for 5 s;
and when the fault arc level is five, limiting the direct current power to zero, and recovering to be normal after the direct current power is continuously maintained for 6 s.
6. The method for detecting the direct-current fault arc of the photovoltaic system according to claim 5, wherein the determining whether the fault arc occurs according to the arc extinguishing determination result comprises:
if the PV current is smaller than a preset fault threshold value after the PV current is recovered to be normal, judging that the fault arc occurs;
and if the PV current is greater than or equal to the preset fault threshold value after the PV current is recovered to be normal, determining that the arc extinction judgment is false alarm, and adjusting the preset current threshold value and the preset power threshold value when the false alarm times meet the preset times threshold value.
7. The method according to claim 6, wherein after determining that the current arc extinguishing decision is false alarm, the method further comprises:
Determining a frequent period and an idle period of the false alarm according to the time period of the false alarm;
in the frequent period, the preset current threshold and the preset power threshold are increased;
and in the idle period, reducing the preset current threshold and the preset power threshold.
8. The method according to any one of claims 1 to 7, wherein the obtaining of the PV current and the PV instantaneous power on the DC side of the photovoltaic system comprises:
and sampling the PV current and the PV voltage in real time according to a preset frequency, and calculating the PV instantaneous power at different moments according to the sampled PV current and PV voltage.
9. A detection device for a photovoltaic system direct current fault arc is characterized by comprising:
the acquisition module is used for acquiring PV current and PV instantaneous power at the direct current side of the photovoltaic system;
the grade module is used for determining the current sudden change grade of the PV current when the change rate of the PV current is greater than a preset current threshold value, and determining the power sudden change grade of the PV instantaneous power when the change rate of the PV instantaneous power is greater than a preset power threshold value;
and the judging module is used for determining a fault arc grade according to the current mutation grade and the power mutation grade if the change rate of the PV current is greater than the preset current threshold and the change rate of the PV instantaneous power is greater than the preset power threshold, performing corresponding arc extinguishing judgment according to the fault arc grade, and judging whether a fault arc occurs according to an arc extinguishing judgment result.
10. A photovoltaic system comprising the apparatus for detecting a dc fault arc in a photovoltaic system of claim 9.
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Citations (28)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB980927A (en) * | 1962-04-17 | 1965-01-20 | Ass Elect Ind | Improvements in and relating to the control of electric arcs |
| GB1062893A (en) * | 1962-12-04 | 1967-03-22 | Reyrolle A & Co Ltd | Improvements relating to the synthetic testing of high voltage electric circuit-breakers |
| JP2000005874A (en) * | 1998-06-19 | 2000-01-11 | Daihen Corp | Power supply device for arc processing |
| US6577484B1 (en) * | 2000-12-12 | 2003-06-10 | Pass & Seymour, Inc. | Arc fault detector device utilizing the di/dt and 60 Hz components of an arcing waveform |
| CN1918680A (en) * | 2003-12-22 | 2007-02-21 | 莱维顿制造有限公司 | Arc fault detector |
| US20070058304A1 (en) * | 2005-09-13 | 2007-03-15 | Michael Parker | Arc fault detection technique |
| CN101039025A (en) * | 2005-12-29 | 2007-09-19 | 森萨塔科技公司 | Low cost arc fault detection technique |
| CN201113388Y (en) * | 2007-10-19 | 2008-09-10 | 吴为麟 | Fault electric arc protector |
| US20110019444A1 (en) * | 2009-07-23 | 2011-01-27 | Enphase Energy, Inc. | Method and apparatus for detection and control of dc arc faults |
| CN102854426A (en) * | 2012-10-09 | 2013-01-02 | 邵俊松 | Method for judging direct current arc fault based on real-time measured multi-band frequency component rate |
| CN103245897A (en) * | 2013-05-02 | 2013-08-14 | 复旦大学 | Detection method for photovoltaic system direct current fault arc by using multicriterion |
| US20140119072A1 (en) * | 2011-07-04 | 2014-05-01 | Sma Solar Technology Ag | Method and System for Detecting an Arc Fault in a Photovoltaic Power System |
| US20140142873A1 (en) * | 2012-11-16 | 2014-05-22 | Keith W. Kawate | Systems and methods of discriminating dc arcs and load switching noise |
| US20140347069A1 (en) * | 2013-05-24 | 2014-11-27 | Det International Holding Limited | Arc detection |
| CN104767480A (en) * | 2015-04-28 | 2015-07-08 | 北京汉能光伏投资有限公司 | Convergence detecting method and system for convergence box and solar power station |
| CN105790207A (en) * | 2016-05-20 | 2016-07-20 | 中国矿业大学 | High-power cut-off type safety barrier |
| US20160282398A1 (en) * | 2015-03-25 | 2016-09-29 | Delta Electronics (Shanghai) Co., Ltd | Method and Device for ARC Fault Detection for Photovoltaic Inverter and Photovoltaic Inverter Using the Same |
| CN106163719A (en) * | 2014-03-07 | 2016-11-23 | 林肯环球股份有限公司 | Open and use combination filler wire to be sent into and the high intensity energy is for the welding system of the root pass welding of multiple tube internal diameter and method |
| JP2017190996A (en) * | 2016-04-13 | 2017-10-19 | 富士電機機器制御株式会社 | Arc failure detection device |
| CN108362981A (en) * | 2018-01-09 | 2018-08-03 | 复旦大学 | A kind of photovoltaic system DC Line Fault arc method for measuring that active/passive detection combines |
| US20190041930A1 (en) * | 2017-12-28 | 2019-02-07 | Intel Corporation | Accurate voltage control to enhance power performance of circuits |
| US20200194999A1 (en) * | 2017-11-08 | 2020-06-18 | Eaton Intelligent Power Limited | Active current injection through a fuse for an electric mobile application |
| US20210036656A1 (en) * | 2018-10-29 | 2021-02-04 | Xi'an Jiaotong University | Arc fault detection method for photovoltaic system based on adaptive kernel function and instantaneous frequency estimation |
| CN112363070A (en) * | 2021-01-14 | 2021-02-12 | 江苏固德威电源科技股份有限公司 | Battery arc discharge detection method and device and battery energy storage system |
| CN112858844A (en) * | 2019-11-27 | 2021-05-28 | 株洲中车时代电气股份有限公司 | Method and system for detecting direct current arc fault in photovoltaic system |
| US20210181264A1 (en) * | 2019-12-12 | 2021-06-17 | Sma Solar Technology Ag | Method of and system for detecting a serial arc fault in a power circuit |
| CN113156272A (en) * | 2020-12-29 | 2021-07-23 | 杭州拓深科技有限公司 | Fault arc cause judgment auxiliary method and device based on current fingerprint technology and storage medium |
| CN114540774A (en) * | 2022-01-29 | 2022-05-27 | 深圳市瀚强科技股份有限公司 | Power supply and arc processing method |
-
2022
- 2022-06-14 CN CN202210668353.3A patent/CN114755546B/en active Active
Patent Citations (28)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB980927A (en) * | 1962-04-17 | 1965-01-20 | Ass Elect Ind | Improvements in and relating to the control of electric arcs |
| GB1062893A (en) * | 1962-12-04 | 1967-03-22 | Reyrolle A & Co Ltd | Improvements relating to the synthetic testing of high voltage electric circuit-breakers |
| JP2000005874A (en) * | 1998-06-19 | 2000-01-11 | Daihen Corp | Power supply device for arc processing |
| US6577484B1 (en) * | 2000-12-12 | 2003-06-10 | Pass & Seymour, Inc. | Arc fault detector device utilizing the di/dt and 60 Hz components of an arcing waveform |
| CN1918680A (en) * | 2003-12-22 | 2007-02-21 | 莱维顿制造有限公司 | Arc fault detector |
| US20070058304A1 (en) * | 2005-09-13 | 2007-03-15 | Michael Parker | Arc fault detection technique |
| CN101039025A (en) * | 2005-12-29 | 2007-09-19 | 森萨塔科技公司 | Low cost arc fault detection technique |
| CN201113388Y (en) * | 2007-10-19 | 2008-09-10 | 吴为麟 | Fault electric arc protector |
| US20110019444A1 (en) * | 2009-07-23 | 2011-01-27 | Enphase Energy, Inc. | Method and apparatus for detection and control of dc arc faults |
| US20140119072A1 (en) * | 2011-07-04 | 2014-05-01 | Sma Solar Technology Ag | Method and System for Detecting an Arc Fault in a Photovoltaic Power System |
| CN102854426A (en) * | 2012-10-09 | 2013-01-02 | 邵俊松 | Method for judging direct current arc fault based on real-time measured multi-band frequency component rate |
| US20140142873A1 (en) * | 2012-11-16 | 2014-05-22 | Keith W. Kawate | Systems and methods of discriminating dc arcs and load switching noise |
| CN103245897A (en) * | 2013-05-02 | 2013-08-14 | 复旦大学 | Detection method for photovoltaic system direct current fault arc by using multicriterion |
| US20140347069A1 (en) * | 2013-05-24 | 2014-11-27 | Det International Holding Limited | Arc detection |
| CN106163719A (en) * | 2014-03-07 | 2016-11-23 | 林肯环球股份有限公司 | Open and use combination filler wire to be sent into and the high intensity energy is for the welding system of the root pass welding of multiple tube internal diameter and method |
| US20160282398A1 (en) * | 2015-03-25 | 2016-09-29 | Delta Electronics (Shanghai) Co., Ltd | Method and Device for ARC Fault Detection for Photovoltaic Inverter and Photovoltaic Inverter Using the Same |
| CN104767480A (en) * | 2015-04-28 | 2015-07-08 | 北京汉能光伏投资有限公司 | Convergence detecting method and system for convergence box and solar power station |
| JP2017190996A (en) * | 2016-04-13 | 2017-10-19 | 富士電機機器制御株式会社 | Arc failure detection device |
| CN105790207A (en) * | 2016-05-20 | 2016-07-20 | 中国矿业大学 | High-power cut-off type safety barrier |
| US20200194999A1 (en) * | 2017-11-08 | 2020-06-18 | Eaton Intelligent Power Limited | Active current injection through a fuse for an electric mobile application |
| US20190041930A1 (en) * | 2017-12-28 | 2019-02-07 | Intel Corporation | Accurate voltage control to enhance power performance of circuits |
| CN108362981A (en) * | 2018-01-09 | 2018-08-03 | 复旦大学 | A kind of photovoltaic system DC Line Fault arc method for measuring that active/passive detection combines |
| US20210036656A1 (en) * | 2018-10-29 | 2021-02-04 | Xi'an Jiaotong University | Arc fault detection method for photovoltaic system based on adaptive kernel function and instantaneous frequency estimation |
| CN112858844A (en) * | 2019-11-27 | 2021-05-28 | 株洲中车时代电气股份有限公司 | Method and system for detecting direct current arc fault in photovoltaic system |
| US20210181264A1 (en) * | 2019-12-12 | 2021-06-17 | Sma Solar Technology Ag | Method of and system for detecting a serial arc fault in a power circuit |
| CN113156272A (en) * | 2020-12-29 | 2021-07-23 | 杭州拓深科技有限公司 | Fault arc cause judgment auxiliary method and device based on current fingerprint technology and storage medium |
| CN112363070A (en) * | 2021-01-14 | 2021-02-12 | 江苏固德威电源科技股份有限公司 | Battery arc discharge detection method and device and battery energy storage system |
| CN114540774A (en) * | 2022-01-29 | 2022-05-27 | 深圳市瀚强科技股份有限公司 | Power supply and arc processing method |
Non-Patent Citations (4)
| Title |
|---|
| XIA, K: "An Arc Fault Detection System for the Household Photovoltaic Inverter according to the DC Bus Currents", 《18TH INTERNATIONAL CONFERENCE ON ELECTRICAL MACHINES AND SYSTEMS (ICEMS)》 * |
| XIANGNING LIN: "Faulty Feeder Detection and Fault Self-Extinguishing by Adaptive Petersen Coil Control", 《IEEE TRANSACTIONS ON POWER DELIVERY》 * |
| 张冠英: "基于周期均值变化率的直流故障电弧检测", 《电气工程学报》 * |
| 王先发: "光伏系统直流侧故障电弧的检测与判别", 《电气技术》 * |
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