CN117526248A - Photovoltaic transformer area fault processing method and system based on extended voltage time strategy - Google Patents
Photovoltaic transformer area fault processing method and system based on extended voltage time strategy Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
- H02J3/0012—Contingency detection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
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Abstract
The invention discloses a photovoltaic transformer area fault processing method and system based on an extended voltage time strategy, which relate to the technical field of photovoltaic power generation and power distribution and comprise the following steps: when a short circuit fault occurs to a circuit connected with a partition switch of the photovoltaic platform area, isolating the fault circuit; after the fault line is isolated, entering an automatic superposition stage, and detecting the voltage and current of the line; judging whether the voltage and the current are normal or not; and judging whether the faults are isolated or not. The invention provides a fault isolation strategy for a photovoltaic platform region, and combines current or voltage fault information to realize self-adaptive processing. By expanding the voltage time strategy, the method adopts different isolation strategies according to line faults, and the stability and reliability of the system are enhanced. Meanwhile, an automatic superposition method is designed, and the isolation and recovery information is combined, so that rapid and automatic fault processing is realized, and the efficiency is improved.
Description
Technical Field
The invention relates to the technical field of photovoltaic power generation and power distribution, in particular to a photovoltaic transformer area fault processing method and system based on an extended voltage time strategy.
Background
With more and more distributed photovoltaic power sources and energy storage devices connected to the 400V transformer area, higher requirements are put on the protection and automation level of the 400V transformer area. With the popularization of renewable energy sources, the traditional power supply mode of the power distribution network of the photovoltaic transformer area is difficult to meet the load requirement, the novel power distribution network of the photovoltaic transformer area is continuously enlarged in scale and increased in complexity, the capacity of the distributed photovoltaic power supply is continuously increased in the global scope, and the capacity of the distributed photovoltaic power supply is expected to continuously increase in the next few years. An automated fault handling method is needed to enable rapid and accurate detection and isolation of faults to reduce impact and loss to the grid.
However, there is a great difference in the short-circuit current output by the photovoltaic power supply and the energy storage device based on the power electronics and the conventional motor element. The short-circuit fault current of the photovoltaic power supply and the energy storage device is limited by the internal resistance, the output power, the parallel connection mode and other factors, and generally cannot exceed 1.32 times of rated current, while the short-circuit fault current of a conventional motor element can reach 10-15 times of the rated current, even tens of thousands of amperes. Meanwhile, due to space and cost limitations, it is difficult to arrange a sufficient number of measuring elements and to establish a perfect communication system, resulting in difficulty in timely obtaining accurate fault information after a fault occurs. These problems result in difficulties in accurately isolating faults after a 400V network has failed, and in fault reclosing after fault isolation. According to statistical data, the occurrence rate of fault coincidence in the current 400V transformer area exceeds 15%, and the safety and the power supply quality of the power grid are affected in a non-negligible way.
Therefore, there is an urgent need to propose an automated method for fault handling suitable for photovoltaic cells, so as to solve the above-mentioned problems.
Disclosure of Invention
The present invention has been made in view of the above-described problems.
Therefore, the technical problems solved by the invention are as follows: due to space and cost constraints, it is difficult to arrange a sufficient number of measurement elements and to build a complete communication system, resulting in a difficulty in obtaining accurate fault information in time after a fault occurs.
In order to solve the technical problems, the invention provides the following technical scheme: the photovoltaic district fault processing method based on the extended voltage time strategy comprises the following steps,
when a short circuit fault occurs to a circuit connected with a partition switch of the photovoltaic platform area, isolating the fault circuit; after the fault line is isolated, entering an automatic superposition stage, and detecting the voltage and current of the line; judging whether the voltage and the current are normal or not; and judging whether the faults are isolated or not.
As a preferable scheme of the photovoltaic transformer area fault processing method based on the extended voltage time strategy, the photovoltaic transformer area fault processing method based on the extended voltage time strategy comprises the following steps: the step of isolating the fault line comprises the step of opening a breaker on the upstream of a disconnecting switch and a disconnecting switch on a connected bus to isolate the fault line when a short circuit fault occurs on a line connected with the disconnecting switch of the photovoltaic platform region.
The fault line isolation further comprises the steps of automatically judging and determining the area needing to be isolated according to the fault position information and a preset fault isolation strategy, and controlling isolation equipment to implement actions by sending control signals.
The performing act includes opening or closing an isolating switch and shutting off power.
As a preferable scheme of the photovoltaic transformer area fault processing method based on the extended voltage time strategy, the photovoltaic transformer area fault processing method based on the extended voltage time strategy comprises the following steps: the control isolation equipment performs actions including monitoring the state of the isolation equipment in real time, performing data interaction with a communication system, and automatically adjusting the data transmission frequency according to data mobility and communication delay based on a self-adaptive algorithm in the interaction process.
The isolation device is selected for operation based on the type and severity of the fault.
The adaptive algorithm includes, when the communication delay exceeds a threshold, increasing the data transmission interval, denoted,
T＝T×(1+α×(D-D 1 ))
when the data mobility is below the threshold, the data transmission interval is reduced, denoted,
T＝T×(1-β×(F-F 1 ))
wherein T represents a data transmission interval, D represents a real-time communication delay, alpha, beta represent a positive integer less than 1, D 1 Represents a communication delay threshold, F represents real-time data fluidity, F 1 Representing a data fluidity threshold.
As a preferable scheme of the photovoltaic transformer area fault processing method based on the extended voltage time strategy, the photovoltaic transformer area fault processing method based on the extended voltage time strategy comprises the following steps: the automatic reclosing stage comprises the steps of opening and closing the circuit breaker, starting to reclose from the minimum number i connected with the circuit breaker, starting to reclose one by one, and analyzing the current reclosing condition.
Judging whether the voltage and the current are normal or not, if the low voltage or the current is detected, indicating that a non-transient fault exists, simultaneously disconnecting the isolating switch, and continuing the subsequent isolating switch superposition operation, and if the voltage or the current is normal, namely that no abnormality is detected, recovering the normal power supply of the circuit.
As a preferable scheme of the photovoltaic transformer area fault processing method based on the extended voltage time strategy, the photovoltaic transformer area fault processing method based on the extended voltage time strategy comprises the following steps: the analysis of the current coincidence condition comprises judging whether the current coincidence condition is coincident with the last partition switch n of the circuit breaker, if the current coincidence condition is coincident with the last partition switch n, the fault is isolated, if the current coincidence condition is not coincident with the last partition switch, the i+1th partition switch is coincident, and judging whether the voltage and the current are normal again.
And after the fault is isolated, adopting an automatic superposition strategy and adding a safety and protection mechanism according to the recovery condition after the fault is isolated.
As a preferable scheme of the photovoltaic transformer area fault processing method based on the extended voltage time strategy, the photovoltaic transformer area fault processing method based on the extended voltage time strategy comprises the following steps: the automatic reclosing strategy includes that during fault handling, the system will continuously collect historical data including voltage, current, fault type, number of reclosing success and failure at the time of the fault and time required for reclosing.
After fault isolation, the system analyzes recovery conditions after fault isolation, including grid voltage and grid stability parameters, and automatically optimizes superposition parameters through an adaptive learning algorithm.
The automatic optimization coincidence parameter comprises the steps of collecting historical data and initializing the weight w and the bias b of a logistic regression model.
And predicting the success probability of superposition according to the current power grid state by using a logistic regression model.
The logistic regression model is expressed as.
Based on the predicted coincidence success rate and the actual coincidence result, the weights and biases of the model are updated using a gradient ascent method, expressed as,
wherein σ represents a sigmoid function, T represents a transpose, x (T) represents a feature vector of time T, η represents a learning rate, and w new And w old Representing the weight vectors after and before updating b new And b old Representing the weight vectors after and before updating, R (t) represents the true coincidence result at time t, Σ t The sum is represented by a sum,representing the predicted output of the logistic regression model at time t.
As a preferable scheme of the photovoltaic transformer area fault processing method based on the extended voltage time strategy, the photovoltaic transformer area fault processing method based on the extended voltage time strategy comprises the following steps: the security and protection mechanism includes collecting historical data of the system and predicting the probability of failure through a logistic regression model.
The probability of the failure of the prediction is expressed as,
wherein w is 0 w 1 w 2 w 3 w 4 w 5 w 6 w 7 w 8 Representing weights of model, x 1 Representing the average voltage, x, of the last five coincidences 2 Represents the average current of the last 5 times of coincidence, x 3 Represents the number of failures in the last 5 coincidences, x 4 Representing stability in a power gridFixed parameters, lambda w 2 Is a regularization term, λ represents a regularization strength parameter.
If the probability of the predicted failure exceeds the threshold, stopping the automatic reclosing process, adding the threshold of the continuous reclosing failure times and adjusting in real time, if the number of the continuous reclosing failures exceeds the threshold, stopping further reclosing attempts by the system, and after the continuous reclosing failure, giving out a warning by the system.
Between successive coincidence attempts, a time interval threshold is set, and if the time interval threshold is not met, further coincidence attempts are prohibited.
Another object of the present invention is to provide a photovoltaic cell fault handling system based on an extended voltage time strategy, which can efficiently isolate faults, automatically handle faults and intelligently optimize superposition parameters through an adaptive learning algorithm, a real-time communication optimization and an intelligent security check mechanism, so as to solve the problems of single fault handling means, slow response speed, lack of intelligent adjustment and insufficient security of the photovoltaic cell in the prior art.
In order to solve the technical problems, the invention provides the following technical scheme: photovoltaic district fault handling system based on extension voltage time strategy includes: the system comprises a fault monitoring module, a fault isolation module, a communication module, an automatic reclosing module and an adaptive learning algorithm module.
The fault monitoring module is responsible for monitoring voltage and current parameters of the photovoltaic transformer area in real time.
And the fault isolation module automatically judges and determines the region needing to be isolated according to the fault position information and a preset fault isolation strategy.
The communication module is used for carrying out data interaction with the isolation equipment and other system modules.
The automatic reclosing module is used for predicting the success probability of reclosing according to the power grid state and the historical data information and determining whether reclosing is carried out or not.
The self-adaptive learning algorithm module is used for optimizing the coincidence parameter according to the historical data and the real-time feedback by using a logistic regression machine learning method.
A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor, when executing the computer program, implements the steps of a photovoltaic cell failure handling method based on an extended voltage time strategy as described above.
A computer readable storage medium having stored thereon a computer program, characterized in that the computer program when executed by a processor implements the steps of a photovoltaic cell failure handling method based on an extended voltage time strategy as described above.
The invention has the beneficial effects that: the invention provides a fault isolation overall strategy aiming at distribution point constraint of a photovoltaic platform area power supply, and the photovoltaic platform area fault processing automatic method based on the voltage expansion time strategy can adopt different fault isolation strategies according to faults of different lines by analyzing fault information of current or voltage in the photovoltaic platform area, so that the self-adaptability of the system is realized, and the stability and reliability of the system are improved. The superposition strategy combines fault isolation and recovery information, realizes superposition after fault isolation through reasonable time sequence control and automatic switching, and can improve fault processing efficiency while reducing human intervention.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:
fig. 1 is an overall flowchart of a photovoltaic cell failure processing method based on an extended voltage time strategy according to a first embodiment of the present invention.
Fig. 2 is an overall frame diagram of a photovoltaic cell failure handling system based on an extended voltage time strategy according to a second embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a conventional photovoltaic cell according to a photovoltaic cell fault handling method based on an extended voltage time strategy according to a third embodiment of the present invention.
Fig. 4 is a schematic structural diagram of a novel photovoltaic cell according to a photovoltaic cell fault handling method based on an extended voltage time strategy according to a third embodiment of the present invention.
Detailed Description
So that the manner in which the above recited objects, features and advantages of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments, some of which are illustrated in the appended drawings. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways other than those described herein, and persons skilled in the art will readily appreciate that the present invention is not limited to the specific embodiments disclosed below.
Further, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic can be included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
While the embodiments of the present invention have been illustrated and described in detail in the drawings, the cross-sectional view of the device structure is not to scale in the general sense for ease of illustration, and the drawings are merely exemplary and should not be construed as limiting the scope of the invention. In addition, the three-dimensional dimensions of length, width and depth should be included in actual fabrication.
Also in the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper, lower, inner and outer", etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first, second, or third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The terms "mounted, connected, and coupled" should be construed broadly in this disclosure unless otherwise specifically indicated and defined, such as: can be fixed connection, detachable connection or integral connection; it may also be a mechanical connection, an electrical connection, or a direct connection, or may be indirectly connected through an intermediate medium, or may be a communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
Example 1
Referring to fig. 1, for one embodiment of the present invention, there is provided a photovoltaic cell fault handling method based on an extended voltage time strategy, which is characterized in that:
s1: and when the circuit connected with the isolating switch of the photovoltaic transformer area has short-circuit fault, isolating the fault circuit.
Further, isolating the faulty line includes, when a short-circuit fault occurs in a line connected to the isolating switch of the photovoltaic transformer area, opening a circuit breaker upstream of the isolating switch and the isolating switch on the bus connected to the isolating switch, and isolating the faulty line.
Isolating the fault line further comprises automatically judging and determining the region needing to be isolated according to the fault position information and a preset fault isolation strategy, and controlling the isolation equipment to implement actions by sending a control signal.
The action includes opening or closing an isolating switch and cutting off the power supply.
Controlling the isolation equipment to implement actions comprises monitoring the state of the isolation equipment in real time, performing data interaction with a communication system, and automatically adjusting the data transmission frequency according to the data mobility and the communication delay based on an adaptive algorithm in the interaction process.
The isolation device is selected for operation based on the type and severity of the fault.
The adaptive algorithm includes, when the communication delay exceeds a threshold, increasing the data transmission interval, denoted,
T＝T×(1+α×(D-D 1 ))
when the data mobility is below the threshold, the data transmission interval is reduced, denoted,
T＝T×(1-β×(F-F 1 ))
wherein T represents a data transmission interval, D represents a real-time communication delay, alpha, beta represent a positive integer less than 1, D 1 Represents a communication delay threshold, F represents real-time data fluidity, F 1 Representing a data fluidity threshold.
S2: after the fault line is isolated, an automatic reclosing stage is entered, and the voltage and current of the line are detected.
The automatic reclosing stage comprises the steps of separating the switches from the minimum number i connected with the circuit breaker after the circuit breaker is closed and starting to reclose one by one, and analyzing the current reclosing condition.
S3: and judging whether the voltage and the current are normal or not.
Judging whether the voltage and the current are normal or not, if the low voltage or the current is detected, indicating that a non-transient fault exists, simultaneously disconnecting the isolating switch, and continuing the subsequent isolating switch superposition operation, and if the voltage or the current is normal, namely that no abnormality is detected, recovering the normal power supply of the circuit.
S4: and judging whether the faults are isolated or not.
Further, analyzing the current superposition condition includes judging whether the superposition of the last partition switch n of the circuit breaker is performed, if the superposition of the last partition switch n is performed, the fault is isolated, if the superposition of the last partition switch is not performed, the i+1th partition switch is performed, and judging whether the voltage and the current are normal again.
And after the fault is isolated, adopting an automatic superposition strategy and adding a safety and protection mechanism according to the recovery condition after the fault is isolated.
An auto-reclosing strategy involves the system continuously collecting historical data during the fault process, including voltage, current, fault type, number of reclosing successes and failures at the time of the fault, and time required for reclosing.
After fault isolation, the system analyzes recovery conditions after fault isolation, including grid voltage and grid stability parameters, and automatically optimizes superposition parameters through an adaptive learning algorithm.
The automatic optimization of the coincidence parameter includes collecting historical data, initializing weights w and bias b of the logistic regression model.
And predicting the success probability of superposition according to the current power grid state by using a logistic regression model.
The logistic regression model is represented as,
based on the predicted coincidence success rate and the actual coincidence result, the weights and biases of the model are updated using a gradient ascent method, expressed as,
wherein σ represents a sigmoid function, T represents a transpose, x (T) represents a feature vector of time T, η represents a learning rate, and w new And w old Representing the weight vectors after and before updating b new And b old Representing the weight vectors after and before updating, R (t) represents the true coincidence result at time t, Σ t The sum is represented by a sum,representing logistic regression modelsModel predictive output at time t.
Further, the security and protection mechanism includes collecting historical data of the system and predicting the probability of failure through a logistic regression model.
The probability of the failure of the prediction is expressed as,
wherein w is 0 w 1 w 2 w 3 w 4 w 5 w 6 w 7 w 8 Representing weights of model, x 1 Representing the average voltage, x, of the last five coincidences 2 Represents the average current of the last 5 times of coincidence, x 3 Represents the number of failures in the last 5 coincidences, x 4 Representing stable parameters in the power grid, lambda w 2 Is a regularization term, λ represents a regularization strength parameter.
If the probability of the predicted failure exceeds the threshold, stopping the automatic reclosing process, adding the threshold of the continuous reclosing failure times and adjusting in real time, for example, the historical data shows that reclosing is frequently failed, correspondingly reducing the threshold of the continuous reclosing failure, if the number of the continuous reclosing failures exceeds the threshold, stopping further reclosing attempts by the system, and sending a warning after the continuous reclosing failure.
Between successive coincidence attempts, a time interval threshold is set, and if the time interval threshold is not met, further coincidence attempts are prohibited.
Example 2
Referring to fig. 2, for one embodiment of the present invention, a system for a photovoltaic cell fault handling method based on an extended voltage time strategy is provided, where the photovoltaic cell fault handling system based on the extended voltage time strategy includes a fault monitoring module, a fault isolation module, a communication module, an auto-reclosing module, and an adaptive learning algorithm module.
The fault monitoring module is responsible for monitoring voltage and current parameters of the photovoltaic transformer area in real time; the fault isolation module automatically judges and determines the region to be isolated according to the fault position information and a preset fault isolation strategy; the communication module is used for carrying out data interaction with the isolation equipment and other system modules; the automatic reclosing module is used for predicting the success probability of reclosing according to the power grid state and the historical data information and determining whether reclosing is carried out or not; the self-adaptive learning algorithm module is used for optimizing the coincidence parameter according to the historical data and the real-time feedback by using a logistic regression machine learning method.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a Read-only memory (ROM), a random access memory (RAM, randomAccessMemory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
Logic and/or steps represented in the flowcharts or otherwise described herein, e.g., a ordered listing of executable instructions for implementing logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). In addition, the computer readable medium may even be paper or other suitable medium on which the program is printed, as the program may be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory.
It is to be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, may be implemented using any one or combination of the following techniques, as is well known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like.
Example 3
Referring to fig. 3 to 4, in this embodiment, in order to verify the beneficial effects of the present invention, scientific demonstration is performed through economic benefit calculation and simulation experiments. The embodiment provides an automatic photovoltaic platform region fault processing method based on an extended voltage time strategy, which comprises the following steps:
for the detection of the characteristics of the voltage or current signal by the sensors in the photovoltaic cell.
Based on the detected information, the change of the voltage or current is analyzed and the occurrence of a fault is identified, and then the power supply of the fault line is cut off, characterized in that the breaker upstream of the fault split-cut-off switch and all breaking switches connected to the breaker are opened.
And executing automatic reclosing operation, controlling the actions of corresponding isolating switches, circuit breakers or other isolating devices, isolating fault areas and recovering normal power supply in other areas. The method is characterized in that a breaker is closed, breaking switches of a power supply network are closed in a delayed mode one by one, and a fault line is judged by detecting the characteristics of voltage or current on the lines after superposition.
As shown in fig. 3, the conventional photovoltaic cell is configured to supply power to the load by only one main line due to the low power supply load. In the traditional photovoltaic platform area structure, a photovoltaic power supply, a circuit breaker, a circuit and a breaking switch are connected in series to supply power for a load.
The fault processing method of the traditional photovoltaic platform area comprises the following steps:
step one, a short circuit fault is found in a certain section of line (the fault is assumed to occur in a section B of line), and the fault is isolated after the upstream breaker QF1 is disconnected and all the breaking switches on the line are disconnected.
And secondly, performing automatic reclosing operation, namely closing the breaker QF1, and then sequentially closing breaking switches QS1, QS2 and QS3 after the breaker.
And step three, checking voltage or current signals every time a section of circuit is overlapped. When the breaking switch on the B section line is closed, the breaking switch is opened. For transient faults, normal power supply can be restored after superposition; for non-transient faults, a fault signal of low voltage or over current may occur. The breaking switch on the line is opened again and QS3 remains open.
As shown in fig. 4, the novel photovoltaic transformer area has a structure schematic diagram, a large amount of load is integrated into a power grid in the novel photovoltaic transformer area, and the power grid is in a radial form. Observing from a protection installation place, all the traditional generators at the power supply side can be equivalent to a traditional generator, all the new energy sources at the power supply side can be equivalent to a new energy source, and after a power grid line has a short-circuit fault, the short-circuit current flowing through a short-circuit point is provided by the traditional generator and the new energy source together.
After the novel transformer area distribution network has line short-circuit faults, the mutual influence and interconnection between lines become more troublesome due to the complexity of the power supply network, and the automatic fault treatment faces new problems. Compared with the serial circuit in the traditional structure, the fault positions of the distributed load circuit are more dispersed, and the difficulty of fault diagnosis is increased. As the proportion of parallel lines in a power system increases, more and more load lines are connected in parallel to the power supply network bus, and isolation of fault lines becomes more difficult. The traditional fault handling method of the photovoltaic transformer area faces the difficult problem of fault isolation. In the new grid structure, the reclosing operation after the recovery of the fault becomes more complex. Because of the distributed load line fault location dispersion, multiple breaking switches need to be operated and detected to ensure that the fault has been relieved and normal power is restored.
Specifically, the photovoltaic platform region fault processing automation method based on the extended voltage time strategy is characterized in that on the basis of a certain superposition program, breaking switches are turned on one by one in a delayed mode, normal power supply of a non-fault line can be recovered by judging the voltage or current of each line, and the specific position of the fault line in the photovoltaic platform region can be accurately identified and isolated.
Specifically, the method for automating the fault handling of the photovoltaic cell based on the extended voltage time strategy is characterized in that the extended voltage time strategy is essentially a method based on comparing the duration of the voltage abnormality in the photovoltaic cell with a preset threshold value, and the threshold value represents the upper limit of the allowable duration of the voltage abnormality so as to identify the fault.
The photovoltaic transformer area fault processing automation method based on the extended voltage time strategy is characterized by comprising the following specific steps of:
step one, detecting the characteristics of a voltage or current signal through a sensor in a photovoltaic platform area;
and secondly, analyzing the change condition of voltage or current and identifying the occurrence of a fault based on the detected information, and if a short-circuit fault occurs in a line where the QS4 is positioned, cutting off the power supply of the fault line, and cutting off a breaker QF1 at the upstream of a fault split-cut switch and all breaking switches QS3, QS4 and QS5 connected with the breaker.
And step three, executing automatic reclosing operation, controlling the actions of corresponding isolating switches, circuit breakers or other isolating devices, isolating fault areas and recovering normal power supply in other areas. The method is characterized in that a breaker QF1 is closed, breaking switches QS3, QS4 and QS5 of a power supply network are respectively closed in a delayed mode one by one, faults are judged by detecting the characteristics of voltage or current on the overlapped lines, and the breaking switches QS3 and QS5 on the overlapped normal lines recover normal power supply. When the breaking switch QS4 is closed, the normal power supply can be recovered after the instantaneous faults are overlapped; for non-transient faults, a fault signal of low voltage or overcurrent occurs, and the breaking switch QS4 is opened again.
The photovoltaic platform region fault processing automatic method based on the extended voltage time strategy is characterized in that the fault isolation strategy considers the position constraint of a photovoltaic platform region distributed power supply, and proper isolation equipment and measures are selected according to distributed power supply distribution information and distance from a fault position so as to ensure that only a fault region is isolated without affecting the operation of other lines when a fault occurs.
Specifically, the method for sending the control signal to the corresponding isolation device to realize the isolation operation comprises the following steps:
according to the fault position information and a preset fault isolation strategy, automatically judging and determining an area needing to be isolated;
by sending control signals, corresponding isolation equipment is controlled to perform actions including, but not limited to, operations of opening or closing an isolation switch, cutting off a power supply and the like;
specifically, the method for automatizing the fault handling of the photovoltaic transformer area based on the extended voltage time strategy is characterized in that the method for sending the control signal to the corresponding isolation equipment to realize the isolation operation further comprises the following steps:
the state of the isolation equipment is monitored in real time, and data interaction is carried out with a communication system, so that the accuracy and reliability of the isolation operation are ensured;
depending on the type and severity of the fault, appropriate isolation equipment is selected to operate to minimize the scope of the fault.
Specifically, the photovoltaic transformer area fault processing automation method based on the extended voltage time strategy is characterized in that the method for realizing connection recovery of a fault area and other areas by adopting an automatic superposition strategy according to recovery conditions after fault isolation comprises the following steps:
analyzing recovery conditions after fault isolation, wherein the recovery conditions comprise parameters such as power grid voltage or current stability and the like so as to ensure the feasibility of connection recovery;
the power load and the power supply capacity of the fault area are monitored, the recovery time is determined, and the situation that excessive load impact is not caused to the power system when the fault area is recovered to be connected is ensured;
specifically, the method for automatizing the fault handling of the photovoltaic transformer area based on the extended voltage time strategy is characterized in that the method for realizing the connection recovery of the fault area and other areas by adopting the automatic superposition strategy according to the recovery condition after fault isolation further comprises the following steps:
and flexibly adjusting the priority and sequence of connection restoration according to the system requirements and strategies so as to restore the power supply capacity of the photovoltaic platform area to the maximum extent.
It should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered in the scope of the claims of the present invention.
Claims (10)
1. The photovoltaic transformer area fault processing method based on the extended voltage time strategy is characterized by comprising the following steps of:
when a short circuit fault occurs to a circuit connected with a partition switch of the photovoltaic platform area, isolating the fault circuit;
after the fault line is isolated, entering an automatic superposition stage, and detecting the voltage and current of the line;
judging whether the voltage and the current are normal or not;
and judging whether the faults are isolated or not.
2. The photovoltaic cell failure handling method based on extended voltage time strategy according to claim 1, wherein: the step of isolating the fault line comprises the step of disconnecting a breaker on the upstream of a disconnecting switch and a disconnecting switch on a connected bus when a short circuit fault occurs in a line connected with the disconnecting switch of the photovoltaic platform region;
the fault line isolation further comprises the steps of automatically judging and determining an area needing to be isolated according to the fault position information and a preset fault isolation strategy, and controlling isolation equipment to implement actions by sending control signals;
the performing act includes opening or closing an isolating switch and shutting off power.
3. The photovoltaic cell failure processing method based on the extended voltage time strategy according to claim 2, wherein: the control isolation equipment performs actions including monitoring the state of the isolation equipment in real time, performing data interaction with a communication system, and automatically adjusting the data transmission frequency according to data mobility and communication delay based on a self-adaptive algorithm in the interaction process;
selecting isolation equipment to operate according to the fault type and severity;
the adaptive algorithm includes, when the communication delay exceeds a threshold, increasing the data transmission interval, denoted,
T＝T×(1+α×(D-D 1 ))
when the data mobility is below the threshold, the data transmission interval is reduced, denoted,
T＝T×(1-β×(F-F 1 ))
wherein T represents a data transmission interval, D represents a real-time communication delay, alpha, beta represent a positive integer less than 1, D 1 Represents a communication delay threshold, F represents real-time data fluidity, F 1 Representing a data fluidity threshold.
4. The photovoltaic cell failure handling method based on extended voltage time strategy according to claim 3, wherein: the step of entering the automatic reclosing stage comprises the steps of starting to separate the switches from the minimum number i connected with the circuit breaker after the circuit breaker is closed, starting to reclose one by one, and analyzing the current reclosing condition;
judging whether the voltage and the current are normal or not, if the low voltage or the current is detected, indicating that a non-transient fault exists, simultaneously disconnecting the isolating switch, and continuing the subsequent isolating switch superposition operation, and if the voltage or the current is normal, namely that no abnormality is detected, recovering the normal power supply of the circuit.
5. The photovoltaic cell failure processing method based on the extended voltage time strategy according to claim 4, wherein: the current superposition condition is analyzed, namely whether the superposition of the last partition switch n of the circuit breaker is judged, if the superposition of the last partition switch n is already carried out, the fault is isolated, if the superposition of the last partition switch is not carried out, the superposition of the (i+1) partition switch is carried out, and whether the voltage and the current are normal is judged again;
and after the fault is isolated, adopting an automatic superposition strategy and adding a safety and protection mechanism according to the recovery condition after the fault is isolated.
6. The photovoltaic cell failure processing method based on the extended voltage time strategy according to claim 5, wherein: the automatic reclosing strategy comprises that in the fault processing process, the system continuously collects historical data, including voltage, current, fault type, reclosing success and failure times and reclosing time;
after fault isolation, the system analyzes recovery conditions after fault isolation, including power grid voltage and power grid stability parameters, and automatically optimizes superposition parameters through a self-adaptive learning algorithm;
the automatic optimization coincidence parameter comprises the steps of collecting historical data, and initializing the weight w and the bias b of a logistic regression model;
predicting the success probability of superposition according to the current power grid state by using a logistic regression model;
the logistic regression model is represented as,
based on the predicted coincidence success rate and the actual coincidence result, the weights and biases of the model are updated using a gradient ascent method, expressed as,
wherein σ represents a sigmoid function, T represents a transpose, x (T) represents a feature vector of time T, η represents a learning rate, and w new And w old Representing the weight vectors after and before updating b new And b old Representing the weight vectors after and before updating, R (t) represents the true coincidence result at time t, Σ t The sum is represented by a sum,representing the predicted output of the logistic regression model at time t.
7. The photovoltaic cell failure processing method based on the extended voltage time strategy according to claim 6, wherein: the safety and protection mechanism comprises the steps of collecting historical data of a system and predicting failure probability through a logistic regression model;
the probability of the failure of the prediction is expressed as,
wherein w is 0 w 1 w 2 w 3 w 4 w 5 w 6 w 7 w 8 Representing weights of model, x 1 Representing the average voltage, x, of the last five coincidences 2 Represents the average current of the last 5 times of coincidence, x 3 Represents the number of failures in the last 5 coincidences, x 4 Representing stable parameters in the power grid, lambda w 2 Is a regularization term, λ represents a regularization strength parameter;
if the probability of the predicted failure exceeds the threshold value, stopping the automatic reclosing process, adding the threshold value of the continuous reclosing failure times and adjusting in real time, if the number of the continuous reclosing failures exceeds the threshold value, stopping further reclosing attempts by the system, and after the continuous reclosing failure, giving out a warning by the system;
between successive coincidence attempts, a time interval threshold is set, and if the time interval threshold is not met, further coincidence attempts are prohibited.
8. A system employing the extended voltage time strategy based photovoltaic cell failure handling method of any of claims 1-7, characterized by: the system comprises a fault monitoring module, a fault isolation module, a communication module, an automatic superposition module and a self-adaptive learning algorithm module;
the fault monitoring module is used for monitoring voltage and current parameters of the photovoltaic transformer area in real time;
the fault isolation module automatically judges and determines the region to be isolated according to the fault position information and a preset fault isolation strategy;
the communication module is used for carrying out data interaction with the isolation equipment and other system modules;
the automatic reclosing module is used for predicting the success probability of reclosing according to the power grid state and the historical data information and determining whether reclosing is carried out or not;
the self-adaptive learning algorithm module is used for optimizing the coincidence parameter according to the historical data and the real-time feedback by using a logistic regression machine learning method.
9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the extended voltage time policy based photovoltaic cell failure handling method of any of claims 1 to 7 when the computer program is executed.
10. A computer readable storage medium having stored thereon a computer program, characterized in that the computer program when executed by a processor implements the steps of the extended voltage time strategy based photovoltaic cell failure handling method according to any of claims 1 to 7.
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