CN116660701B - Arc detection method and system - Google Patents
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Abstract
The invention relates to the technical field of fault arc detection, in particular to an arc detection method and an arc detection system, which are used for acquiring an output signal of a photovoltaic system at the current sampling moment and extracting a characteristic value in the output signal as a current characteristic quantity; determining whether a fault arc occurs according to the current feature quantity and the current feature threshold value; if a fault arc occurs, corresponding protection measures are carried out; the current characteristic threshold is adjusted according to the initial characteristic threshold and an MPPT state in the MPPT controller; the MPPT state includes power and voltage at a maximum power point. The scheme of the invention can avoid misoperation of the photovoltaic system and accurately detect arc faults.
Description
Technical Field
The present invention relates generally to the field of fault arc detection technology. More particularly, the present invention relates to an arc detection method and system.
Background
Arcing is a discharge phenomenon that occurs in conductors through which large currents flow, due to poor contact caused by unreliable connection of joints or degradation of insulation of joints and wires, and unreliable connection between contacts or between contacts and other conductors. The electric arc is a main cause of fire in the direct current system, and the occurrence of the electric arc is timely and accurately detected, so that the safety and the reliability of the direct current system are directly affected.
For arc detection, as the application publication number is CN 115308549A, the invention discloses an arc detection method, an electronic device and an inverter, which are used for judging whether the output voltage of a photovoltaic string of a photovoltaic system is regulated, if so, stopping arc detection, and when the output current of the photovoltaic string meets the preset condition, determining an arc characteristic value according to the output voltage of the photovoltaic string and the output current of the photovoltaic string, and further determining an arc detection result according to the arc characteristic value.
In the prior art, the problem of interference of output voltage and output current mutation of a photovoltaic string on arc detection is considered, but the problem that the external environment change or accidental factors cause illumination change to cause system working points and system electric quantity change is solved, particularly, under abnormal illumination conditions, the MPPT algorithm dynamically adjusts the working points of the photovoltaic system, the electric quantity of the photovoltaic system is lower than that of the photovoltaic system in normal conditions, the corresponding output characteristic curve and the system electric quantity are lower than those in normal conditions, at the moment, once a fault arc occurs, the acquired characteristic quantity often cannot reach a set threshold value, the initial characteristic threshold value of the fault arc judgment characteristic quantity set under normal illumination fails, the device fails, the fault arc cannot be accurately detected, namely, the photovoltaic system has larger potential arc fault threat caused, the small current fault arc is continuously combusted, and the system is also damaged by enough energy, fire is initiated, and life and property loss is caused.
Disclosure of Invention
In order to solve one or more of the technical problems, the invention provides that the initial characteristic threshold value of arc fault detection is adjusted by adopting the power and the voltage of the maximum power point, so that the problem of misoperation of the PV state is avoided under the complex illumination condition, and meanwhile, the arc fault can be accurately detected close to the occurrence time of the fault; to this end, the present invention provides a solution in two aspects as follows.
The invention provides an arc detection method, which comprises the following steps:
acquiring an output signal of a photovoltaic system at the current sampling moment, and extracting a characteristic value in the output signal as a current characteristic quantity;
determining whether a fault arc occurs according to the current feature quantity and the current feature threshold value; if a fault arc occurs, corresponding protection measures are carried out;
the current characteristic threshold is adjusted according to the initial characteristic threshold and an MPPT state in the MPPT controller; the MPPT state comprises power and voltage of a maximum power point;
the MPPT controller is provided with a storage unit and a cache unit; at the time t0, the maximum power point corresponding to the photovoltaic system is m0 information, when the illumination condition is changed, the MPPT control algorithm immediately operates and automatically searches the maximum power point, in the process that the MPPT algorithm does not automatically track the maximum power point, the information stored by the storage unit is m0 information, and the MPPT state is directly read from the storage unit; when the current sampling time T1 is reached, the MPPT algorithm automatically tracks the maximum power point, the maximum power point corresponding to the photovoltaic system is information of m1, the information stored by the storage unit is information of m1, the information of m0 is covered, the MPPT state is directly read from the caching unit, the caching unit is used for caching the information of m0 between the time T1 and the time T1 to the time T1 plus T, and T is the caching set time.
Optionally, when the MPPT algorithm is not started, the current feature threshold is the initial feature threshold.
Optionally, the current feature threshold is:
wherein P is t0 The power of the maximum power point at the time t0, P is the rated power under normal illumination, V t0 The voltage of the maximum power point at the time t0 is V which is the rated voltage under normal illumination, alpha t1 For the current feature threshold value, alpha, of the current sampling instant t1 0 As the initial feature threshold, the time t0 is a time before the time t 1.
Optionally, the current feature threshold is:
when V is t0 <V is then
When V is t0 When not less than V
Wherein, beta and mu are respectively the voltage V of the maximum power point t0 And power P t0 Weights, P of (2) t0 Power at maximum power point at time t0P is the rated power under normal illumination, V t0 The voltage of the maximum power point at the time t0 is V which is the rated voltage under normal illumination, alpha t1 For the current feature threshold value, alpha, of the current sampling instant t1 0 As the initial feature threshold, the time t0 is a time before the time t 1.
Optionally, the current feature threshold is:
wherein Δv is the difference between the voltage at the maximum power point at time t0 and the rated voltage under normal illumination, i.e., Δv=v t0 -V，P t0 The power of the maximum power point at the time t0, P is the rated power under normal illumination, V t0 The voltage of the maximum power point at the time t0 is V which is the rated voltage under normal illumination, alpha t1 For the current feature threshold value, alpha, of the current sampling instant t1 0 As the initial feature threshold, the time t0 is a time before the time t 1.
Alternatively, the current feature quantity is obtained by analyzing the time domain characteristics and the frequency domain characteristics of the acquired output signal and extracting the feature value of the signal by using fast fourier transform and wavelet transform.
Optionally, when a fault arc occurs and occurs N times in succession, corresponding protection measures are taken.
The invention also provides an arc detection system, comprising:
a processor; and
a memory storing computer instructions for arc detection that, when executed by the processor, cause the apparatus to perform one of the arc detection methods described above.
The beneficial effects of the invention are as follows:
according to the scheme, the initial characteristic threshold value is adjusted according to the MPPT state, so that the problem of misoperation of the state of the photovoltaic system can be avoided.
Furthermore, the storage unit and the cache unit are arranged in the MPPT controller, so that the maximum power point can be directly read from the storage unit when the maximum power point is not automatically found by the MPPT algorithm at the current sampling moment; when the MPPT algorithm automatically finds out the maximum power point at the current sampling moment, the maximum power point is directly read from the buffer unit; compared with the existing adjustment of the value of the working point which is changed at the moment in the MPPT control algorithm, the maximum power point is always the point corresponding to the moment before the current sampling moment, the adjustment of the characteristic threshold value of the arc fault detection is carried out, so that the problem that the state of the photovoltaic system is likely to generate misoperation due to the working point which is in an instantaneous state is avoided under the complex illumination condition, and meanwhile, the fault arc can be accurately detected close to the fault occurrence moment.
Drawings
The above, as well as additional purposes, features, and advantages of exemplary embodiments of the present invention will become readily apparent from the following detailed description when read in conjunction with the accompanying drawings. In the drawings, embodiments of the invention are illustrated by way of example and not by way of limitation, and like reference numerals refer to similar or corresponding parts and in which:
fig. 1 is a block diagram of a photovoltaic system in the present embodiment;
FIG. 2 is a flow chart showing steps of an arc detection method in the present embodiment;
FIG. 3 is a schematic view of P-V characteristic curves under different illumination and temperatures;
FIG. 4 is a schematic diagram of I-V characteristic curves at different illumination and temperatures;
fig. 5 is a block diagram of the structure of an arc detection system in the present embodiment.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.
Fig. 1 is a block diagram of the structure of a photovoltaic system for arc detection of the present embodiment.
As shown in fig. 1, the photovoltaic system of the present embodiment includes a photovoltaic power generation device, a storage battery connected to the photovoltaic power generation device, and a load;
the photovoltaic power generation device comprises a photovoltaic cell assembly, a DC-DC converter, an MPPT controller and an arc detection module, wherein the output end of the photovoltaic cell assembly is connected to the input end of the DC-DC converter; the output of the DC-DC converter is connected to a battery and a load for providing an adapted voltage to the battery and the load.
The arc detection module is connected with the MPPT controller and is used for receiving data sent by the MPPT controller, detecting whether a fault arc occurs in the photovoltaic battery assembly or not, and executing corresponding protection measures; specifically, the arc detection module is used for collecting output signals in the photovoltaic power generation device, analyzing the output signals to obtain current characteristic quantity, comparing the current characteristic quantity with a current characteristic threshold value, and when the current characteristic quantity is larger than the current characteristic threshold value, generating fault arcs of the photovoltaic system and adopting corresponding control measures.
Including but not limited to voltage signals, current signals, etc. The output signal in this embodiment is sampled at a frequency of 10KHz-100KHz.
The MPPT controller is in control connection with the DC-DC converter and is used for controlling the DC-DC converter according to the fault detection result of the arc detection module.
The main functions of the MPPT controller are as follows: the photovoltaic system is always positioned near the maximum power point of power generation to obtain the highest efficiency. Specifically, the MPPT controller continuously detects the current and voltage change of the photovoltaic battery assembly and adjusts the PWM driving signal duty ratio of the DC-DC converter according to the change of the current and voltage change, so that the maximum power output of the photovoltaic battery assembly is realized. When the MPPT algorithm is active, it indicates that the photovoltaic cell assembly is not maintaining the initial normal operating state, which requires adjustment of the PWM drive signal duty cycle of the DC-DC converter.
When the MPPT controller performs the maximum power tracking of the photovoltaic power generation device, the voltage and the power of the maximum power point tracked in real time are stored in the storage unit of the MPPT controller at the same time.
The MPPT controller further comprises a buffer unit, configured to buffer a maximum power point corresponding to a time before the current sampling time. Specifically, for the current sampling time T1, the maximum power point corresponding to the time T0 is stored, the buffer time is continued from the time T1 to the time t1+t, the time T0 is the time before the current sampling time T1, and T is the buffer setting time.
The arc detection module can also obtain the maximum power point cached by the caching unit in the MPPT controller, and adjust the initial characteristic threshold according to the maximum power point to obtain the current characteristic threshold, so that the fault detection of the photovoltaic system can be conveniently and accurately carried out, and the photovoltaic system can be operated more stably.
Based on the above photovoltaic system, the invention provides an arc detection method, as shown in fig. 2, comprising the following steps:
acquiring an output signal of a photovoltaic system at the current sampling moment, and extracting a characteristic value in the output signal as a current characteristic quantity;
determining whether a fault arc occurs according to the current feature quantity and the current feature threshold value; if a fault arc occurs, corresponding protection measures are carried out;
the current characteristic threshold is adjusted according to the initial characteristic threshold and an MPPT state in the MPPT controller; the MPPT state includes power and voltage at a maximum power point.
The current characteristic quantity can be obtained by carrying out characteristic value statistics on a high-frequency signal obtained by high-pass filtering and a low-frequency signal obtained by low-pass filtering in a current detection mode; specifically, the characteristic value of the fault current is extracted by utilizing fast fourier transform and wavelet transform through analyzing the time domain characteristic and the frequency domain characteristic of the output current signal, and when the current characteristic value is larger than the current characteristic threshold value during fault judgment, arc faults occur. Since the current feature quantity is obtained as the prior art, the description is not repeated here.
Before the current feature threshold value is adjusted, the method further comprises the step of judging whether an MPPT algorithm in the MPPT controller acts, and specifically, when the MPPT algorithm acts, a maximum power point is obtained; determining a current characteristic threshold according to the initial characteristic threshold and the power and voltage of the maximum power point; when the MPPT algorithm is not operated, the current feature threshold is the initial feature threshold.
The specific process for judging whether the MPPT algorithm acts is as follows:
and acquiring a level signal of a port of the MPPT controller, wherein when the level signal is a high level signal and is kept for a period of time, an MPPT algorithm in the MPPT controller acts, otherwise, when the level signal is a low level signal and is kept for a period of time, the MPPT algorithm in the MPPT controller does not act.
It should be noted that whether the MPPT controller acts depends on different illumination conditions, namely when illumination is under normal illumination conditions, the U-I output characteristic curve of the photovoltaic system is unchanged; once complex illumination conditions (namely, the conditions of shielding other targets, changing the weather from sunny to cloudy and the like under short-time illumination) are entered, the U-I output characteristic curve of the photovoltaic system is changed at the moment, the U-I output characteristic curve is necessarily lower than the U-I output characteristic curve in normal illumination, a new working point is necessarily generated, and the MPPT controller is touched to act so as to adjust the working point until the output power of the system is maximum.
In this embodiment, the arc detection module obtains the MPPT state in the MPPT controller according to the received signal indicating whether the MPPT algorithm is active, and determines the current feature threshold according to the initial feature threshold and the MPPT state in the MPPT controller.
The MPPT states in the MPPT obtaining controller in the above embodiment are: according to a storage unit and a cache unit which are set by an MPPT controller, when the MPPT algorithm does not automatically find the maximum power point at the current sampling moment, the MPPT state is directly read from the storage unit; and when the MPPT algorithm automatically finds the maximum power point at the current sampling moment, the MPPT state is directly read from the buffer unit.
The MPPT controller is provided with a storage unit A1 and a buffer unit A2, where the storage unit A1 is configured to store MPP (maximum power point) information at the current time. Specifically, at time t0, assuming that the illumination condition is g0, the MPP point corresponding to the photovoltaic system is m0, at this time, the storage unit A1 stores information of m0 in real time, when the illumination condition is changed, the MPPT control algorithm operates immediately, and after the operation is completed, and the maximum power point is automatically tracked, assuming that the time t1 is the time, the illumination condition is g1, the MPP point m1 corresponding to the photovoltaic system is stored in the storage unit A1, at this time, the storage unit A1 covers the information of m0 at the time t 0. It should be noted that, since the MPP point is the maximum power point automatically tracked by the MPPT control algorithm in the running process, the MPPT control algorithm has not found the maximum power point automatically between the time t0 and the time t1, and the information of m0 is still stored in the storage unit A1, and then the obtained MPPT state is the information of m0 directly read from the storage unit A1 between the time t0 and the time t 1; at time T1, the MPPT control algorithm has found the maximum power point corresponding to the time, and then, at time T1 and in the period from T1 to t1+t, the obtained MPPT state is the information of m0 directly read from the cache unit A2; the buffer unit A2 buffers m0 information between time T1 and time T1 to time t1+t, where T is a buffer setting time.
The scheme of caching the maximum power point at the moment before the current sampling moment can avoid the problem that the previous data is lost due to data coverage in a storage unit, so that the initial characteristic threshold cannot be adjusted by utilizing the historical maximum power point before the current sampling moment, and the fault arc is inaccurate to detect.
The initial characteristic threshold value in the step corresponds to the normal illumination environment where the photovoltaic system is located and the photovoltaic system works in a rated state (P, V), wherein P and V are rated power and rated voltage in the normal illumination environment. It should be noted that, if a fault arc is detected, only the faulty photovoltaic block is cut off instead of the whole photovoltaic system, that is, the remaining photovoltaic cell modules still work normally, and the initial characteristic threshold value at this time needs to be reinitialized according to the output working point of the photovoltaic system at this time.
It should be noted that, the initial feature threshold is adjusted by using the historical maximum power point before the current sampling time: on one hand, considering that the MPPT control algorithm at the current sampling moment searches for the possible existing time of the current MPP point is too long, and the new MPP point at the current sampling moment cannot be found immediately; therefore, if the MPPT control algorithm at the current sampling moment is searching for an MPP point, in order to quickly realize the detection of the fault arc, the MPP point at the moment before the current sampling moment is directly adopted, wherein the MPP point is the maximum power point;
on the other hand, even if the MPP point of the current sampling time is found, the MPP point of a certain time before the current sampling time of the current sampling time is adopted, so that the MPP point can be more matched with the fault occurrence time and is closer to the fault occurrence time, and the fault arc detection judgment is more accurate. Meanwhile, compared with the characteristic quantity threshold corrected according to the dynamically adjusted working point of the MPPT controller in the prior art, misoperation of the photovoltaic system can be avoided, and the maximum power point is utilized for adjusting the initial characteristic threshold, so that the operation of the photovoltaic system is more stable.
In this embodiment, the current feature threshold is determined according to the initial feature threshold and the MPPT state in the MPPT controller, which includes the following embodiments:
one embodiment is as follows: according to the power of the maximum power point, the current characteristic threshold value is obtained as follows:
α t1 =α 0 （P t0 /P）
wherein P is t0 The power of the maximum power point at the time t0, P is the rated power under normal illumination, alpha t1 For the current characteristic threshold value corresponding to the current sampling time t1, alpha 0 As an initial feature threshold, time t0 precedes time t 1.
Further, in order to more accurately detect the fault arc, another embodiment is as follows: according to the power and voltage of the maximum power point, the current characteristic threshold value is obtained, specifically:
setting weights of power and voltage of a maximum power point to be beta and mu respectively;
calculating a current characteristic threshold value, namely:
when V is t0 <V is then
When V is t0 When not less than V
Wherein, beta and mu are respectively the voltage V of the maximum power point t0 And power P t0 Weights, P of (2) t0 The power of the maximum power point at the time t0 before the current sampling time t1 is the rated power under normal illumination, V t0 The voltage of the maximum power point at the time t0 before the current sampling time t1 is V which is the rated voltage under normal illumination, alpha t1 For the current feature threshold value, alpha, of the current sampling instant t1 0 Is the initial feature threshold.
It should be noted that the values of β and μ are 0.4 and 0.6, respectively; of course, the values of β and μ also need to be weighted according to practical situations, and generally μ should be larger.
Meanwhile, in the above embodiment, the magnitude of the voltage of the selected maximum power point and the voltage under the normal illumination needs to be considered, that is, the voltage of the maximum power point may be larger than the rated voltage of the normal illumination, which is related to the temperature factor, particularly see fig. 3 and fig. 4, and then the formula of the current feature threshold needs to be adjusted when this occurs.
Another embodiment is: determining a current characteristic threshold according to the product of the power and the voltage of the maximum power point, wherein the current characteristic threshold is as follows:
wherein P is t0 The power of the maximum power point at the time t0, and P is the rated power under normal illuminationPower, V t0 The voltage of the maximum power point at the time t0 is V which is the rated voltage under normal illumination, alpha t1 For the current feature threshold value, alpha, of the current sampling instant t1 0 Is the initial feature threshold.
Another embodiment is: determining a current characteristic threshold according to the difference value between the power and the voltage of the maximum power point and the rated voltage, and specifically:
wherein Δv is the difference between the voltage at the maximum power point at time t0 and the rated voltage under normal illumination, i.e., Δv=v t0 -V，P t0 The power of the maximum power point at the time t0, P is the rated power under normal illumination, V t0 The voltage of the maximum power point at the time t0 is V which is the rated voltage under normal illumination, alpha t1 For the current feature threshold value, alpha, of the current sampling instant t1 0 Is the initial feature threshold.
The voltage of the maximum power point is introduced into the three embodiments, so that the current characteristic threshold can be comprehensively analyzed from two dimensions of power and voltage, the adjustment of the initial characteristic threshold is realized, and the detection of the fault arc can be more accurately realized.
In this embodiment, in response to the current feature quantity being greater than the current feature threshold, a fault arc occurs, otherwise, whether the fault arc occurs in the photovoltaic system at the current sampling time can be determined without the occurrence of the fault arc.
In this embodiment, when it is determined that a fault arc occurs, N times of determination are further required continuously, that is, when N times of continuous faults occur, corresponding protection measures are adopted. Wherein the value range of N is more than or equal to 3; in this embodiment, the value of N is 3, that is, when the number of times of fault judgment reaches 3 continuously, it is proved that the fault arc always occurs, the fault cannot disappear, and corresponding protection measures should be performed at this time; by detecting the fault arc continuously for a plurality of times, the accident of single fault arc is avoided, and the accuracy of fault arc detection is improved.
According to the technical scheme, under different illumination conditions, the power and the voltage of the maximum power point of the MPPT are adopted to adjust the initial characteristic threshold, compared with the value of the working point which is changed at moment in the existing MPPT controller algorithm, the problem that misoperation is possibly caused by the PV state when the working point in the instantaneous state is adopted is avoided under the complex illumination condition, and meanwhile, the arc fault can be accurately detected more closely to the fault occurrence moment.
Fig. 5 is a block diagram of a configuration for an arc detection system according to an embodiment of the present invention.
The invention also provides an arc detection system. As shown in fig. 5, the apparatus comprises a processor and a memory storing computer program instructions which, when executed by the processor, implement a method of arc detection according to the first aspect of the invention.
The device also includes other components, such as a communication bus and a communication interface, which are well known to those skilled in the art, and the arrangement and function of which are known in the art and therefore not described in detail herein.
In the context of this patent, the foregoing memory may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. For example, the computer readable storage medium may be any suitable magnetic or magneto-optical storage medium, such as, for example, resistance change Memory RRAM (Resistive Random Access Memory), dynamic Random Access Memory DRAM (Dynamic Random Access Memory), static Random Access Memory SRAM (Static Random-Access Memory), enhanced dynamic Random Access Memory EDRAM (Enhanced Dynamic Random Access Memory), high-Bandwidth Memory HBM (High-Bandwidth Memory), hybrid storage cube HMC (Hybrid Memory Cube), etc., or any other medium that may be used to store the desired information and that may be accessed by an application, a module, or both. Any such computer storage media may be part of, or accessible by, or connectable to, the device. Any of the applications or modules described herein may be implemented using computer-readable/executable instructions that may be stored or otherwise maintained by such computer-readable media.
While various embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Many modifications, changes, and substitutions will now occur to those skilled in the art without departing from the spirit and scope of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention.
Claims (8)
1. An arc detection method, comprising the steps of:
acquiring an output signal of a photovoltaic system at the current sampling moment, and extracting a characteristic value in the output signal as a current characteristic quantity;
determining whether a fault arc occurs according to the current feature quantity and the current feature threshold value; if a fault arc occurs, corresponding protection measures are carried out;
the current characteristic threshold is adjusted according to the initial characteristic threshold and an MPPT state in the MPPT controller; the MPPT state comprises power and voltage of a maximum power point;
the MPPT controller is provided with a storage unit and a cache unit; at the time t0, the maximum power point corresponding to the photovoltaic system is m0 information, when the illumination condition is changed, the MPPT control algorithm immediately operates and automatically searches the maximum power point, in the process that the MPPT algorithm does not automatically track the maximum power point, the information stored by the storage unit is m0 information, and the MPPT state is directly read from the storage unit; when the current sampling time T1 is reached, the MPPT algorithm automatically tracks the maximum power point, the maximum power point corresponding to the photovoltaic system is information of m1, the information stored by the storage unit is information of m1, the information of m0 is covered, the MPPT state is directly read from the caching unit, the caching unit is used for caching the information of m0 between the time T1 and the time T1 to the time T1+T, and T is the caching set time.
2. The arc detection method of claim 1, wherein the current characteristic threshold is the initial characteristic threshold when an MPPT algorithm is not activated.
3. The arc detection method of claim 1 wherein the current characteristic threshold is:
wherein P is t0 The power of the maximum power point at the time t0, P is the rated power under normal illumination, V t0 The voltage of the maximum power point at the time t0 is V which is the rated voltage under normal illumination, alpha t1 For the current feature threshold value, alpha, of the current sampling instant t1 0 As the initial feature threshold, the time t0 is a time before the time t 1.
4. The arc detection method of claim 1 wherein the current characteristic threshold is:
when V is t0 <V is then
When V is t0 When not less than V
Wherein, beta and mu are respectively the voltage V of the maximum power point t0 And power P t0 Weights, P of (2) t0 The power of the maximum power point at the time t0, P is the rated power under normal illumination, V t0 The voltage of the maximum power point at the time t0 is V which is the rated voltage under normal illumination, alpha t1 For the current feature threshold value, alpha, of the current sampling instant t1 0 As the initial feature threshold, the time t0 is a time before the time t 1.
5. The arc detection method of claim 1 wherein the current characteristic threshold is:
wherein Δv is the difference between the voltage at the maximum power point at time t0 and the rated voltage under normal illumination, i.e., Δv=v t0 -V，P t0 The power of the maximum power point at the time t0, P is the rated power under normal illumination, V t0 The voltage of the maximum power point at the time t0 is V which is the rated voltage under normal illumination, alpha t1 For the current feature threshold value, alpha, of the current sampling instant t1 0 As the initial feature threshold, the time t0 is a time before the time t 1.
6. The arc detection method according to claim 1, wherein the current feature quantity is a feature value of the signal extracted by performing analysis of time domain characteristics and frequency domain characteristics of the acquired output signal and using fast fourier transform and wavelet transform.
7. An arc detection method according to claim 1, characterized in that when a fault arc occurs and N consecutive occurrences, the corresponding protection measures are taken.
8. An arc detection system, comprising:
a processor; and
a memory storing computer instructions for arc detection, which when executed by the processor, cause the apparatus to perform an arc detection method according to any one of claims 1-7.
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