CN113687185A - Double-conductor topological direct-current arc diagnosis and positioning method and system - Google Patents
Double-conductor topological direct-current arc diagnosis and positioning method and system Download PDFInfo
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Abstract
The invention provides a method and a system for diagnosing and positioning a double-conductor topological direct current arc, which comprises the following steps: and (3) double-conductor topology step: replacing one wire connecting two electrical components in the direct current system with two wires; a current monitoring step: carrying out current collection on the double wires between the two electrical components to provide a basis for arc fault diagnosis; an arc diagnosis step: analyzing and judging the acquired current of the two wires, and diagnosing the arc fault according to the deviation of the current values of the two wires; and (3) fault positioning: and monitoring each section of double conductors in the direct current system, and positioning the fault to the abnormal conductor according to the abnormal current data. The invention adopts a double-conductor circuit topology, can avoid the occurrence of series direct current arc faults and has obvious arc protection effect; meanwhile, the fault detection circuit is free from the interference of environmental noise and high-frequency signals brought by various switching devices in the system, has good robustness, can accurately detect the parallel arc fault, and has no malfunction and refusal.
Description
Technical Field
The invention relates to the technical field of direct current system electric appliance fault diagnosis, in particular to a double-conductor topology direct current arc diagnosis and positioning method and system.
Background
The photovoltaic power generation system, the energy storage system, the direct current charging pile and other direct current systems are all provided with modularized and multi-joint wiring. For example, a photovoltaic power plant is made up of thousands of photovoltaic array modules, the series-parallel connection of which typically results in a large number of junctions and connection points at the connection; the energy storage power station is composed of a large number of battery modules, and the number of joints and connection points is large; tens of thousands of direct current charging piles also have a large number of connector connection points. With long-term operation of the dc system, these joint connections can create small air gaps due to joint loosening and the like, which can break down at a certain voltage and cause series dc arc faults. In addition, as the operation time becomes longer, the parallel direct current arc fault is caused again by the reasons of wire breakage, insulation aging and the like. Compared with the arc phenomenon in an alternating current system, the arc in the direct current system has no zero-crossing point characteristic, and is difficult to detect; and most direct current systems such as photovoltaic systems and energy storage power stations are close to civil buildings, and the damage caused by fire accidents caused by electric arcs is larger. Research shows that more than 60% of fire accidents in the photovoltaic system are caused by direct current arc faults. Therefore, dc arc fault diagnosis, localization and protection have become the subject of research in the industry.
At present, direct current arc diagnosis and positioning method research is mainly divided into two categories, namely: the method mainly relates to a time domain analysis method, a frequency domain analysis method and a time-frequency domain combination method. The arc detection method based on physical characteristics needs additional detection equipment, is only limited to small closed space occasions such as a switch cabinet and a direct current combiner box, and is not strong in universality; the detection method based on the electric signal change is easily interfered by environmental noise and system background noise, and normal operations such as load switching, inverter starting and the like also can influence the detection algorithm, so that the probability of false operation and rejection is high. In addition, research shows that the arc volatility is weakened in a direct current system with the power of more than 15A, weak arc characteristics are presented, and high-frequency characteristics are basically the same as those in a normal condition, so that certain difficulty is caused in detecting direct current arc faults by adopting a frequency domain characteristic method. In a photovoltaic direct current system, the current limiting characteristic and the Maximum Power Point Tracking (MPPT) characteristic of a photovoltaic module also bring certain difficulty to the detection of a direct current arc.
In the current research, patent document CN112462176A proposes a method for detecting and locating an arc fault in a photovoltaic string, which includes two steps, where the first step analyzes the total current after the convergence of each photovoltaic string to determine whether an arc fault occurs, if it is determined that an arc fault occurs, the second step is performed, otherwise, the analysis of the total current data in the next period in the first step is repeated, and the second step analyzes the string-level current and the string-level voltage of each string, and when there is a decrease in the string-level voltage and an increase in the string-level current in a plurality of strings, the remaining strings with a decrease in the string-level voltage, a decrease in the string-level current, or a reversal in the string-level voltage are regarded as a dc arc fault. Although the method can realize most direct current arc detection and group serial fault location, the arc characteristics are not obvious when weak arc faults occur, a total current analysis method is adopted in the first step, each group serial current is converged, the arc characteristics are further weakened, and therefore misjudgment occurs, and when the arc faults are located when the parallel arc faults occur among the groups, the defect that only one fault group string can be identified exists, and the fault group string has a locating defect.
Chinese patent publication No. CN110618366A discloses a dc arc detection method and apparatus. The direct current arc detection method comprises the steps of firstly collecting current signals of each path of MPPT in a photovoltaic power generation system, and then analyzing the current signals of each path of MPPT respectively to obtain a current analysis result of each path of MPPT; and then, judging whether the current analysis result of each MPPT does not accord with the arc characteristics, if the current analysis result of at least one MPPT accords with the arc characteristics, judging that the MPPT has circuit faults, and outputting an arc fault alarm signal to a system controller in the photovoltaic power generation system.
Patent document CN110763958A proposes a dc arc detection method based on a neural network, which improves the arc detection accuracy of the existing method, but still has a certain misjudgment rate, and training of the neural network requires a large amount of practical data, which is difficult to train and implement, and the neural network of the dc system with different topologies and voltage and current levels needs to be retrained, and thus the generality is not high. At present, direct current arc fault location research is just started, and research of a direct current arc fault diagnosis and location method with high accuracy has become an important subject concerned by academia and industry.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method and a system for diagnosing and positioning a double-wire topology direct current arc.
The invention provides a double-wire topology direct current arc diagnosis and positioning method, which comprises the following steps:
and (3) double-conductor topology step: replacing one wire connecting two electrical components in the direct current system with two wires;
a current monitoring step: carrying out current collection on the double wires between the two electrical components to provide a basis for arc fault diagnosis;
an arc diagnosis step: and analyzing and judging the acquired current of the two wires, and diagnosing the arc fault according to the deviation of the current values of the two wires.
And (3) fault positioning: and monitoring each section of double conductors in the direct current system, and positioning the fault to the abnormal conductor according to the abnormal current data.
Preferably, each of the two wires used in the two-wire topology step can meet the current-carrying requirements of the two connected electrical components.
Preferably, the positive electrode of each electrical component has two terminals and the negative electrode has two terminals, each of the two wires being independently connected to one of the terminals of the electrical component.
Preferably, when the lengths of the two wires are greater than a set value, the specification of the wires needs to consider the influence generated by the resistance voltage drop of the wires, so that when one of the wires is disconnected, the voltage difference between two ends of the disconnected point of the wire is less than 80V.
Preferably, in the arc diagnosis step, when the current of one of the two wires is reduced to 0A and the current of the other wire is increased to 2 times of the original current, it indicates that the wire with the current of 0A in the section of the two wires has an open-circuit fault; when the current of two wires in the double wires is not 0, the current values of the two wires are different in size and have larger deviation, and the positions of the two wires at two positions have the change at the same time, the parallel arc fault is shown to occur; when the current of the two wires in the double wires is not 0 and the current of the two wires is approximately equal, the arc fault does not occur.
Preferably, in the current monitoring step, a current monitoring module is adopted to monitor the current of the wire, and the sampling frequency of the current monitoring module is 1-10 kHz.
The invention provides a double-wire topology direct current arc diagnosis and positioning system, which comprises the following modules:
two-wire topology module: replacing one wire connecting two electrical components in the direct current system with two wires;
the current monitoring module: carrying out current collection on the double wires between the two electrical components to provide a basis for arc fault diagnosis;
an arc diagnosis module: and analyzing and judging the acquired current of the two wires, and diagnosing the arc fault according to the deviation of the current values of the two wires.
A fault positioning module: and monitoring each section of double conductors in the direct current system, and positioning the fault to the abnormal conductor according to the abnormal current data.
Preferably, each of the two wires used in the two-wire topology module can meet the current-carrying requirements of the two connected electrical components.
Preferably, the positive electrode of each electrical component has two terminals and the negative electrode has two terminals, each of the two wires being independently connected to one of the terminals of the electrical component.
Preferably, when the lengths of the two wires are greater than a set value, the specification of the wires needs to consider the influence generated by the resistance voltage drop of the wires, so that when one of the wires is disconnected, the voltage difference between two ends of the disconnected point of the wire is less than 80V.
Compared with the prior art, the invention has the following beneficial effects:
1. by adopting the double-conductor circuit topology, when one conductor in the double conductors is broken, the other conductor clamps the voltage at two ends of the broken conductor to be very low, thereby eliminating the occurrence condition of direct current electric arc, completely eradicating the occurrence of series direct current electric arc and having good electric arc suppression and protection functions.
2. The double-wire symmetrical operation mode enables various interferences to have the same influence on the two wires, so that the double-wire symmetrical operation mode is free from the interference of environmental noise and high-frequency noise caused by various switching devices in a system, has good robustness, and is free from the interference of shadow shielding, illumination sudden change and the like on a photovoltaic direct current system.
3. The method does not involve complex algorithm solution, has low calculation cost, low sampling frequency requirement (only 1-10kHz) of the current sampling module and low hardware cost.
4. The fault diagnosis is carried out by utilizing the deviation of the double-conductor current, the sensitivity is high, the fault characteristics are obvious, the 100% accurate detection of the arc fault can be realized, and the possibility of misoperation and refusal action does not exist.
5. The method has the advantages that arc fault alarm can also occur on the short circuit between the grounding short circuit and the line, and the short circuit fault can be changed into the arc fault along with the time evolution after the short circuit fault is detected in certain scenes, so that the method has the function of making up for the short circuit fault detection failure of the short circuit protection device and has a certain function of early warning of the arc fault.
6. The positioning precision is high, the element-level arc fault positioning can be realized, and the accurate action of the arc protection device is facilitated.
7. For a long line, when the series direct current arc fault occurs due to large resistance voltage drop of the lead (the probability is small), the method can also realize arc fault alarm and can realize type distinguishing of series arcs and parallel arcs.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic wiring diagram of a two-wire topology DC arc diagnosis and positioning method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a single-to-double joint switching device according to an embodiment of the present invention;
fig. 3 is a schematic wiring diagram of a channel-generalized current acquisition module according to an embodiment of the present invention;
FIG. 4 is a general block diagram of Simulink simulation according to an embodiment of the present invention;
FIG. 5 is a sub-block diagram of a photovoltaic array corresponding to the occurrence of an arc in series and parallel in an embodiment of the invention;
FIG. 6 is a sub-block diagram of a photovoltaic array corresponding to the occurrence of an arc in series-parallel connection in an embodiment of the present invention;
FIG. 7 is a graph of a two-conductor current waveform at a fault when an arc occurs in parallel in series in an embodiment of the invention;
FIG. 8 is a graph of a two-conductor current waveform at a fault when an inter-string parallel arc occurs in an embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
A diagnosis and positioning method for a two-wire topology direct current arc is disclosed, referring to FIG. 1, and comprises the following steps:
and (3) double-conductor topology step: when one wire in the double wires is broken, the other wire clamps the voltage at two ends of the broken wire to be very low to inhibit the generation of the direct current arc, and the effect of protecting the generation of the series direct current arc is achieved.
The current carrying capacity of each wire in the double-wire is the same as that of a wire used in the existing single-wire direct current system, so that the double-wire circuit topology can still normally operate after one wire is opened due to loose joints and the like and the current of the other wire is 2 times higher than that of the other wire.
Each wire in the double wires is independently connected to one connector of the element, namely, the anode of each element is required to have two connectors, the cathode of each element is required to have two connectors, and the two wires are respectively connected to the two corresponding connectors so as to ensure that the two wires have relative independence. The two positive electrode tabs of the element are connected together inside the element, and the two negative electrode tabs of the element are also connected together inside the element. For an element with only one positive connector and one negative connector, a single-double connector conversion device is developed, as shown in fig. 2, so as to realize that the existing electrical element has a double connector connection function.
A current monitoring step: carrying out current collection on the double wires between the two electrical components to provide a basis for arc fault diagnosis;
an arc diagnosis step: analyzing and processing the acquired current data change values on the double conductors, and judging faults, wherein when the current of one conductor in the double conductors is reduced to 0A, and the current of the other conductor is increased to 2 times of the original current, the open-circuit fault (the reasons of wire breakage or joint looseness and the like, and the series direct-current arc fault can be caused in a single-conductor direct-current system) occurs to the conductor with the current of 0A in the section of double conductors; when the current of two wires in the double wires is not 0, the current values of the two wires are different in size and have larger deviation, and the positions of the two wires at two positions have the change at the same time, the parallel arc fault is shown to occur; when the current of the two wires in the double wires is not 0 and the current of the two wires is approximately equal, the arc fault does not occur.
And (3) fault positioning: and positioning the fault to the position of a certain section of double-conductor according to the obvious deviation of the current value of the section of double-conductor, thereby realizing the element-level fault positioning.
The influence caused by the resistance voltage drop of the wires can be ignored when the length of the wires is short, and the influence caused by the resistance voltage drop of the wires needs to be considered when the length of the wires is long. Taking an example that 10A current flows through each of the two wires under normal conditions, the wires are made of the 5 th flexible conductor specified in the national standard GB/T3956-. Therefore, when the double-conductor circuit topology is used for long-line series direct-current arc protection, the influence caused by resistance voltage drop of the conductors needs to be considered, so that the resistance voltage drop of one conductor does not exceed 80V after the other conductor is disconnected. Particularly, when the voltage drop at two ends of a wire resistor with a long length of a direct current cable inevitably exceeds 80V, a series direct current arc fault occurs on a certain wire in the double-wire due to the reasons of joint looseness, wire breakage and the like (or the voltage drop of the wire resistor is smaller than 80V but larger than the maintenance voltage 11-14V of the direct current arc, and the possibility of the occurrence of the direct current arc also exists), the double-wire circuit topology is asymmetrically operated due to the series direct current arc, the current value of the double-wire still has obvious deviation, and the arc fault judgment can be realized. When the current value at one position of the double-conductor has obvious deviation at a certain moment in the direct current system, the series direct current arc fault is shown to occur (the possibility under the double-conductor topology is very low); when the current values at two positions of the double-conductor are obviously deviated at a certain moment in the direct current system, the parallel direct current arc fault is shown.
In the current monitoring step, a current monitoring module is adopted to monitor the current of the wire, the sampling frequency of the current monitoring module is 1-10kHz, the arc fault diagnosis does not involve a complex solving algorithm, and the calculation cost is low.
Current monitoring requires more current sampling modules because each segment of the dual conductor current needs to be sampled. For small direct current application occasions, the method has good applicability; for a large-scale direct current application scene, a channel generalized current acquisition module can be adopted to meet the current sampling requirement required by the method. Or, the current acquisition module is integrated in the existing electrical appliance element so as to meet the current sampling requirement required by the method. In particular, for photovoltaic dc systems, the current acquisition modules required by the present method can be integrated into existing component level monitors, component level power optimizers, and component level shutdown devices to reduce additional hardware costs. A typical wiring schematic for a channel-generalized current acquisition module is shown with reference to fig. 3. A large amount of current data acquired by the method can also provide judgment basis for other types of fault diagnosis, and can provide data basis for future big data intelligent direct current system construction.
And (4) arc diagnosis, wherein when the current of the two wires in the double wires is not 0 and the current of the two wires is approximately equal, the arc fault does not occur. The non-occurrence of the arc fault does not mean that no other fault occurs, and the method does not generate the arc fault alarm when the other fault occurs, namely, the misjudgment does not occur. If partial shadow shielding occurs in the photovoltaic direct current system, the method cannot be influenced, because the topology of the double-wire circuit still runs symmetrically when the shadow shielding occurs, the current deviation is approximately 0 when the current variation trend of the two wires is the same, and thus misjudgment cannot occur. Similarly, the method is not affected by the interference of sudden light change and the like.
Arc diagnostics generate arc fault alarms when ground shorts and line-to-line shorts occur. When the ground short circuit and the line-to-line short circuit occur, the double-conductor topology at the position of the short circuit operates asymmetrically, and the double-conductor current has larger deviation and even deviation value which is far larger than the current deviation caused by the direct current arc, so that the arc fault alarm is given. Considering that the short-circuit fault can cause carbonization ablation at a short-circuit point due to overcurrent heating, when the short-circuit protection device does not act in time, the fault can be further evolved into an arc fault along with the continuation of the short-circuit fault so as to cause fire, and therefore, the method for sending the arc fault alarm when the short-circuit fault occurs is considered to be reasonable. The method can make up the defect that the short-circuit fault protection device has missed judgment in certain scenes, and simultaneously shows that the method has a certain DC arc fault early warning function, thereby being beneficial to further enhancing the safety of a DC system.
The arc diagnosis does not involve complex algorithm solution, no special calculation requirements are required on a data processor, and the required calculation cost is low; the fault location can locate the fault between two electrical components, so that the component-level fault location is realized, and the location precision is high.
The present invention will be further described with reference to specific scenarios.
By taking a photovoltaic direct current system scene as an example, the specific principle and the implementation process of the method are explained by adopting Simulink simulation. As shown in fig. 1, the method for diagnosing and positioning a two-wire topology dc arc according to the present invention includes: two-wire topology, current monitoring, arc diagnostics, and fault localization. The two-wire topology requires that each wire of the two wires be independently connected to the dual terminal of the component to ensure that the two wires are relatively independent. Fig. 1 discloses two-wire implementations: one is to reform the electrical element, so that the anode of the electrical element has two joints, and the cathode also has two joints, namely a double-joint electrical element; one is to adopt a single-double joint conversion device to realize that a single-joint electrical element has a double-joint connection function. Fig. 2 is a schematic diagram of a single-to-double adapter switching device, which can be regarded as a 2-to-1 adapter from left to right and a 1-to-2 adapter from right to left. Fig. 3 is a schematic diagram of wiring of a data channel generalized current collection module for realizing dual-conductor current collection, where n data channels are labeled as data channel 1, data channel 2, …, and data channel n, each data channel is connected to m dual-conductor current collection modules, and each data channel is labeled as dual-conductor current collection 1, dual-conductor current collection 2, …, and dual-conductor current collection m, that is, one host can realize data reading of m × n dual-conductor current collection modules. Fig. 3 only illustrates the wiring schematic diagram of the two-wire current collection module on the data channel 1 in detail, and for the data channels 2 to n, the wiring method is similar to that of the data channel 1, and is not repeated. The m current acquisition modules connected with each data channel acquire currents on two wires at the corresponding double-wire position, and the host machine realizes the sequential reading of data of each current acquisition module through the control of the address bus, so that a basis is provided for the subsequent arc fault diagnosis. Because the sampling frequency of the current acquisition module is low (1-10kHz), the data of all the current acquisition modules on the data channel can be read sequentially through the address bus control in each current sampling period.
As shown in fig. 4, the rationality of the method provided by the invention is verified by building a general simulation block diagram of the photovoltaic direct current system. FIG. 5 is an internal schematic diagram of PV Array sub-modules in a simulation overall block diagram, the sub-block diagram showing the arrangement of components when an arc fault occurs in series and parallel in a photovoltaic DC system; fig. 6 is also an internal schematic diagram of PV Array sub-modules in the simulation overall block diagram, which shows an arrangement manner of components when an inter-string parallel arc fault occurs in the photovoltaic dc system. The parameter design of the photovoltaic module is consistent with that of a Longji-le-leaf 450W photovoltaic module, the open-circuit voltage Uoc of a single module is 49.6V, the short-circuit current Isc is 11.58A, the maximum power point voltage Ump is 41.4V, the maximum power point current Imp is 10.87A, the temperature coefficient of the Isc is + 0.050%/° C, and the temperature coefficient of the Uoc is-0.284%/° C. The photovoltaic arrays in fig. 5 and 6 both adopt an arrangement of 3 sets of series-parallel connection, and each set of the 3 sets of series-parallel connection has 5 components in series, that is, a total of 3 × 5 — 15 photovoltaic components are used in the simulation. There are 3 photovoltaic modules on the left side in fig. 5, and the component arrangement of three photovoltaic modules from top to bottom is in proper order: 1 string of 1 parallel, 2 strings of 1 parallel and 2 strings of 1 parallel, namely, after three photovoltaic modules on the left side are connected in series, 5 strings of 1 parallel are arranged, so that a photovoltaic group string is formed; in the figure, 1 photovoltaic module is arranged on the right side, and the arrangement mode of the components is 5 strings and 2 parallel, so that two photovoltaic group strings are formed. In fig. 5, the series-parallel arc is equivalent to a small resistance of 5 ohms, and the arc fault is controlled to occur at 0.4s through a step module and an ideal switch module, and the total simulation time is 0.8 s. In fig. 6, 2 photovoltaic modules are arranged at the leftmost side, the arrangement of the modules is 1 string 1 parallel and 4 strings 1 parallel from top to bottom, and the two photovoltaic modules are connected in series to form a photovoltaic group string; the middle of the figure is also provided with 2 photovoltaic modules, the arrangement modes of the components are 4 strings 1 parallel and 1 string 1 parallel from top to bottom, and the two photovoltaic modules are connected in series to form a photovoltaic group string; in the figure, the rightmost side is provided with 1 photovoltaic module, the arrangement mode of the components is 5 strings and 1 parallel, and a photovoltaic group string is formed. In fig. 6, the series-parallel arc is still equivalent with a small resistance of 5 ohms, and the remaining parameter settings are the same as in fig. 5. Each wire of the twin-wire in fig. 5 and 6 is serially connected with 2 small resistors, and each small resistor takes a value of 0.0025 ohm, so as to simulate the wire resistor with a length of 1m, that is, the length of the twin-wire between the two components is estimated to be 1m in the simulation.
Fig. 7 shows the current flowing through the double conductors at the fault point when the series-parallel arc fault occurs, the system does not fail in normal operation when 0-0.4s, the currents flowing through the two conductors are equal due to symmetric operation, the parallel arc fault occurs on one of the conductors after 0.4s, the double conductors operate asymmetrically, and the currents of the two conductors have obvious deviation. From this deviation, arc fault diagnosis can be realized. Fig. 8 shows the current flowing through the dual conductors at the fault point when an inter-string parallel arc fault occurs, and the waveform of the current is similar to that of fig. 7, and similarly, the arc fault can be diagnosed. It can be found that when an arc fault occurs, only the double-conductor at the fault point has an asymmetric operation mode, that is, only the current of the double-conductor at the fault point has obvious deviation, and the currents of the double-conductors at other positions still symmetrically operate can not have obvious deviation, so that fault positioning can be realized according to the position of the double-conductor with obvious current deviation. The method can position the fault to a certain section of double-conductor position, so that the element-level fault positioning can be realized, and the positioning precision is high.
The implementation costs required for the process of this patent are analyzed as follows: the cost required by the double-conductor current sampling module is estimated according to the cost of the photovoltaic module level monitor, and the proportion of the required cost to the total construction cost of the power station is estimated to be 1% according to online data collection; with the two-wire topology, the wire usage is doubled, and the ratio of the added cost of the wire to the total cost of the system is estimated to be 0.66%. The wire cost is estimated specifically as follows: according to practical research, taking 885.6kW photovoltaic power station as an example, the total construction cost of the power station is 320 ten thousand yuan, a direct current cable 7000m is adopted, the cable is 3.3 yuan per meter, 7000 × 3 is 2.1 ten thousand yuan in total, and the proportion of the wire cost in the total construction cost of the power station is 2.1 ten thousand/320 ten thousand-0.66%. Thus, the two-wire topology, the wire cost increases by 0.66%. In summary, the implementation cost of the method of the patent accounts for 1% + 0.66% to 1.66% of the total cost.
The invention adopts a double-lead circuit topology, and can prevent the occurrence of series direct current electric arc from the circuit layer (short circuit, when the voltage drop of the circuit is lower); the parallel arc fault diagnosis and fault location can be realized by utilizing the obvious deviation of the current values on the double conductors; the method does not involve complex algorithm solution, and the current sampling module has low sampling rate (only 1-10kHz), thereby reducing the calculation cost and the hardware cost.
Those skilled in the art will appreciate that, in addition to implementing the system and its various devices, modules, units provided by the present invention as pure computer readable program code, the system and its various devices, modules, units provided by the present invention can be fully implemented by logically programming method steps in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system and various devices, modules and units thereof provided by the invention can be regarded as a hardware component, and the devices, modules and units included in the system for realizing various functions can also be regarded as structures in the hardware component; means, modules, units for performing the various functions may also be regarded as structures within both software modules and hardware components for performing the method.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (10)
1. A double-conductor topology direct current arc diagnosis and positioning method is characterized by comprising the following steps:
and (3) double-conductor topology step: replacing one wire connecting two electrical components in the direct current system with two wires;
a current monitoring step: carrying out current collection on the double wires between the two electrical components to provide a basis for arc fault diagnosis;
an arc diagnosis step: and analyzing and judging the acquired current of the two wires, and diagnosing the arc fault according to the deviation of the current values of the two wires.
And (3) fault positioning: and monitoring each section of double conductors in the direct current system, and positioning the fault to the abnormal conductor according to the abnormal current data.
2. The two-wire topology direct current arc diagnosis and localization method according to claim 1, characterized in that: each of the two wires adopted in the two-wire topology step can meet the current-carrying requirements of the two connected electrical components.
3. The two-wire topology direct current arc diagnosis and localization method according to claim 1, characterized in that: the positive pole of each electrical component has two connectors, the negative pole has two connectors, and each of the two wires is independently connected to one connector of the electrical component.
4. The two-wire topology direct current arc diagnosis and localization method according to claim 1, characterized in that: when the lengths of the two wires are larger than a set value, the specification of the wires needs to consider the influence generated by the resistance voltage drop of the wires, so that when one wire is disconnected, the voltage difference between two ends of the disconnected point of the wire is smaller than 80V.
5. The two-wire topology direct current arc diagnosis and localization method according to claim 1, characterized in that: in the arc diagnosis step, when the current of one wire in the double wires is reduced to 0A and the current of the other wire is increased to 2 times of the original current, the open-circuit fault occurs in the wire with the current of 0A in the section of the double wires; when the current of two wires in the double wires is not 0, the current values of the two wires are different in size and have larger deviation, and the positions of the two wires at two positions have the change at the same time, the parallel arc fault is shown to occur; when the current of the two wires in the double wires is not 0 and the current of the two wires is approximately equal, the arc fault does not occur.
6. The two-wire topology direct current arc diagnosis and localization method according to claim 1, characterized in that: in the current monitoring step, a current monitoring module is adopted to monitor the current of the wire, and the sampling frequency of the current monitoring module is 1-10 kHz.
7. A two-wire topology direct current arc diagnosis and positioning system is characterized in that: the system comprises the following modules:
two-wire topology module: replacing one wire connecting two electrical components in the direct current system with two wires;
the current monitoring module: carrying out current collection on the double wires between the two electrical components to provide a basis for arc fault diagnosis;
an arc diagnosis module: and analyzing and judging the acquired current of the two wires, and diagnosing the arc fault according to the deviation of the current values of the two wires.
A fault positioning module: and monitoring each section of double conductors in the direct current system, and positioning the fault to the abnormal conductor according to the abnormal current data.
8. The two-wire topology dc arc diagnostic and locating system of claim 7, wherein: each of the two wires adopted in the double-wire topological module can meet the current-carrying requirements of two connected electrical components.
9. The two-wire topology dc arc diagnostic and locating system of claim 7, wherein: the positive pole of each electrical component has two connectors, the negative pole has two connectors, and each of the two wires is independently connected to one connector of the electrical component.
10. The two-wire topology dc arc diagnostic and locating system of claim 7, wherein: when the lengths of the two wires are larger than a set value, the specification of the wires needs to consider the influence generated by the resistance voltage drop of the wires, so that when one wire is disconnected, the voltage difference between two ends of the disconnected point of the wire is smaller than 80V.
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