CN115514021A - Fault regulation and control method and system for distributed photovoltaic power station and computer equipment - Google Patents

Fault regulation and control method and system for distributed photovoltaic power station and computer equipment Download PDF

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CN115514021A
CN115514021A CN202211414932.1A CN202211414932A CN115514021A CN 115514021 A CN115514021 A CN 115514021A CN 202211414932 A CN202211414932 A CN 202211414932A CN 115514021 A CN115514021 A CN 115514021A
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group
photovoltaic
current
string
value
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CN115514021B (en
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黄炜
何涛
王天安
曹映果
钱凯
梁冰
鲁贵海
张玎一
谭海波
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Yunnan Power Grid Energy Investment Co ltd
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Yunnan Power Grid Energy Investment Co ltd
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/466Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02HEMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00Emergency 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
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/001Methods to deal with contingencies, e.g. abnormalities, faults or failures
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381Dispersed generators
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02SGENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S50/00Monitoring or testing of PV systems, e.g. load balancing or fault identification
    • H02S50/10Testing of PV devices, e.g. of PV modules or single PV cells
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20The dispersed energy generation being of renewable origin
    • H02J2300/22The renewable source being solar energy
    • H02J2300/24The renewable source being solar energy of photovoltaic origin

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  • Power Engineering (AREA)
  • Photovoltaic Devices (AREA)

Abstract

The invention relates to the technical field of distributed photovoltaic power stations, solves the technical problems that a photovoltaic device cannot timely quit a system and automatically cut off isolation when the photovoltaic device fails, and particularly relates to a fault regulation and control method, a system and computer equipment of a distributed photovoltaic power station, wherein the fault regulation and control method comprises the following steps: s1, obtaining an average value D of a plurality of combiner box group current of a photovoltaic power station in a time period T; s2, calculating a weighted average value M of the photovoltaic power station group string current dispersion rate in the time period T according to the average value D; and S3, judging whether the photovoltaic power station is in a stable operation state or not according to the standard discrete rate threshold value P. According to the invention, the running stability of the photovoltaic equipment is judged by circularly monitoring the running stability of the photovoltaic equipment, the photovoltaic equipment with faults is forced to stop running, and the photovoltaic equipment with faults can be quickly cut off and isolated out of the whole system when a certain group of strings have faults, so that the normal running of other equipment is ensured, and the adverse effect on the whole photovoltaic system is avoided.

Description

Fault regulation and control method and system for distributed photovoltaic power station and computer equipment
Technical Field
The invention relates to the technical field of distributed photovoltaic power stations, in particular to a fault regulation and control method, a fault regulation and control system and computer equipment of a distributed photovoltaic power station.
Background
In the application of a distributed photovoltaic power station, a plurality of combiner boxes can only monitor currents of the group strings, the situation that the battery pack flows backwards when the battery panel is partially shielded cannot be automatically controlled, and a fuse is blown or even the battery pack is burnt out under the serious situation, so that the accident caused by the hot spot effect is most prominent.
When hot spot effect or other faults occur to photovoltaic equipment, the faulted photovoltaic equipment can affect the whole photovoltaic power station, the whole system is in a paralyzed state due to disorder of the system when the fault occurs seriously, the control system of the existing distributed photovoltaic power station can not be cut off and isolated in time when a certain photovoltaic equipment breaks down, and the faulted equipment is forced to exit from the whole photovoltaic system, so that the whole photovoltaic system can not run normally, the difficulty in eliminating the fault is increased due to the fact that the conflict is caused by an initial fault, and the corresponding equipment can not be cut off in time when the fault occurs, so that the damage to the corresponding equipment is serious, and the maintenance cost and the economic loss to the photovoltaic equipment are improved.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a fault regulation and control method, a system and computer equipment of a distributed photovoltaic power station, and solves the technical problem that the photovoltaic equipment cannot be timely quitted and automatically cut off and isolated when the photovoltaic equipment breaks down.
In order to solve the technical problems, the invention provides the following technical scheme: a fault regulation and control method of a distributed photovoltaic power station comprises the following steps:
s1, obtaining an average value D of a plurality of combiner box group current of a photovoltaic power station in a time period T;
s2, calculating a weighted average value M of the photovoltaic power station group string current dispersion rate in the time period T according to the average value D;
s3, judging whether the photovoltaic power station is in a stable operation state or not according to the standard discrete rate threshold value P;
if the weighted average value M is not more than the standard dispersion rate threshold value P, the photovoltaic power station is in a stable operation state, the step S1 is returned, and the next time period T +1 is judged again;
if the weighted average value M is larger than the standard dispersion rate threshold value P, the photovoltaic power station breaks down, and the step S4 is carried out;
s4, acquiring a working current value G of each group of strings corresponding to a plurality of photovoltaic groups in a time period T;
s5, calculating a string current discrete rate H of each photovoltaic group according to the working current value G;
s6, judging whether each photovoltaic group is in a stable operation state or not according to the standard discrete rate threshold value P;
if the string current dispersion rate H of the photovoltaic group is less than or equal to the standard dispersion rate threshold value P, the photovoltaic group is in a stable operation state, and after the photovoltaic group is marked as '0', a cyclic verification sequence is removed and the operation is finished;
if the string current discrete rate H of the group is larger than the standard discrete rate threshold value P, the photovoltaic group has a fault, and the step S7 is carried out after the photovoltaic group is marked as '1';
s7, sending a delay unloading instruction to the photovoltaic group marked as '1' and isolating;
and S8, removing the isolated photovoltaic module and sending a group string fault command to the terminal.
Further, in step S2, a weighted average M of the string current dispersion rate of the photovoltaic power plant group in the time period T is calculated according to the average D, and the specific process includes the following steps:
s21, dividing the time period T into a plurality of moments
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Figure 307136DEST_PATH_IMAGE002
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、…、
Figure 679343DEST_PATH_IMAGE004
S22, acquiring a plurality of moments
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、…、
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The current value of the group string corresponding to the next certain header box
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Figure DEST_PATH_IMAGE007
Figure 709878DEST_PATH_IMAGE008
、…、
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S23、According to the group current value
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Figure 437159DEST_PATH_IMAGE007
Figure 655651DEST_PATH_IMAGE008
、…、
Figure 531334DEST_PATH_IMAGE009
Calculating the average current value of the string at the current moment
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S24, average current value according to string
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Calculating the group string current discrete rate Q at the moment t;
s25, according to the time
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Figure 527606DEST_PATH_IMAGE002
Figure 777453DEST_PATH_IMAGE003
、…、
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Corresponding string current dispersion ratio
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Figure DEST_PATH_IMAGE012
Figure 388060DEST_PATH_IMAGE013
、…、
Figure DEST_PATH_IMAGE014
A weighted average M is calculated.
Further, in step S5, a string current dispersion rate H of each photovoltaic group is calculated according to the working current value G, and the specific process includes the following steps:
s51, determining the maximum output voltage effective value of a single group string in each photovoltaic group
Figure 871125DEST_PATH_IMAGE015
And maximum output current effective value
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S52, according to the maximum output voltage effective value
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And maximum output current effective value
Figure 110794DEST_PATH_IMAGE016
Calculating the voltage-current conversion ratio K of the single string;
s53, determining the stable output current A of the single string according to the voltage-current conversion ratio;
s54, determining a working current G according to the stable output current A of the single string;
and S55, calculating the string current dispersion rate H according to the working current value G and the standard deviation of the current string current.
Further, in step S7, a delay unloading instruction is issued to the photovoltaic group marked with "1" and isolation is performed, and the specific process includes the following steps:
s71, detecting working currents of a plurality of groups of strings in the photovoltaic group marked as '1';
if the output current of a certain group of strings is detected to be 0 or a negative value, the solid-state relays on each group of strings are controlled to be immediately switched off through the server, the group of strings are isolated, the isolation time t is set, and the switching-off times are recorded as 1;
s72, circularly detecting the working current of the next string group;
if the output current of a certain group of strings is detected to be 0 or negative again, the same operation as the step S71 is performed;
if not, continuously detecting the working current of the rest strings until completing a detection cycle;
s73, after the isolation time T is exceeded, the server controls the solid-state relay in the off state to be closed again, and the working current is detected again;
if the output current of the group of strings is normal, clearing the disconnection times and removing the isolation limitation;
if the output current of the series is 0 or a negative value, the solid-state relay is disconnected again, the isolation time t is set, the disconnection times are recorded as 2, and the step S72 is entered for circulation;
and S74, acquiring the disconnection time record of each group string and judging whether the group string is removed or not according to a threshold value.
Further, in step S3, the range of the standard discrete rate threshold P is 0% to 10%.
Further, in step S6, the range of the standard discrete rate threshold P is 0% to 5%.
Further, in step S8, the terminal includes a PC, a notebook, a tablet, or a mobile phone.
The technical scheme also provides a system for realizing the fault regulation and control method, and the system comprises:
the first acquisition module is used for acquiring an average value D of a plurality of combiner box group current of the photovoltaic power station in a time period T;
the first calculation module is used for calculating a weighted average value M of the photovoltaic power station group string current discrete rate in a time period T according to the average value D;
the first judgment module is used for judging whether the photovoltaic power station is in a stable operation state or not according to a standard dispersion rate threshold value P;
the second acquisition module is used for acquiring the working current value G of each group of strings corresponding to a plurality of photovoltaic groups in a time period T;
the second calculation module is used for calculating the group string current discrete rate H of each photovoltaic group according to the working current value G;
the second judging module is used for judging whether each photovoltaic group is in a stable running state or not according to the standard discrete rate threshold value P;
the isolation module is used for sending a delay unloading instruction to the photovoltaic group marked as '1' and isolating the photovoltaic group;
the removing module is used for removing the isolated photovoltaic assembly and sending a group string fault command to the terminal.
The technical scheme also provides computer equipment which comprises a processor and a memory, wherein the memory is used for storing a computer program, and the computer program is executed by the processor to realize the fault regulation and control method.
By means of the technical scheme, the invention provides a fault regulation and control method, a system and computer equipment of a distributed photovoltaic power station, which at least have the following beneficial effects:
1. according to the invention, the operation stable state of the photovoltaic equipment is judged by circularly monitoring, so that the failed photovoltaic equipment is automatically detected in time and corresponding cutting and isolating measures are taken, the failed photovoltaic equipment is forced to stop operating, further confirmation is made based on the current dispersion rate, and the photovoltaic equipment can be quickly cut off and isolated to the outside of the whole system when a certain group of strings fail, so that the normal operation of other equipment is ensured, the adverse effect on the whole photovoltaic system is avoided, the forced regulation and control operation on the failed photovoltaic equipment is achieved, the normal operation of the whole photovoltaic power station is ensured, and the damage to the photovoltaic equipment due to the long-term existence of the failure is reduced.
2. According to the invention, under the condition that one or more strings have faults or have low conversion benefit, the strings can be automatically and rapidly isolated, and the influence on other strings is avoided, so that the continuous operation of the whole photovoltaic power station is ensured, and the strings can be rapidly combined into the strings for continuous use after the faults are eliminated, so that the maximum electric energy supply capacity of the photovoltaic power station is ensured, and the continuous output of electric energy is guaranteed.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
FIG. 1 is a flow chart of a fault regulation method of the present invention;
FIG. 2 is a schematic distribution diagram of a distributed photovoltaic power plant of the present invention;
FIG. 3 is a schematic structural diagram of a Hall sensor according to the present invention;
FIG. 4 is a block diagram of a fault regulation system according to the present invention;
fig. 5 is a block diagram of the internal structure of the computer device in the embodiment of the present invention.
In the figure: 10. a first acquisition module; 20. a first calculation module; 30. a first judgment module; 40. a second acquisition module; 50. a second calculation module; 60. a second judgment module; 70. an isolation module; 80. the module is removed.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the detailed description thereof. Therefore, the realization process of how to apply technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented.
The present embodiment is proposed in the following background, and based on the practical problem existing in the long-term operation of the distributed photovoltaic power plant, a specific implementation of a solution is proposed to solve the problem.
In the application of a distributed photovoltaic power station, a plurality of combiner boxes can only monitor currents of the group strings, the situation that the battery pack flows backwards when the battery panel is partially shielded cannot be automatically controlled, and a fuse is blown or even the battery pack is burnt out under the serious situation, so that the accident caused by the hot spot effect is most prominent.
That is, the partially generated current of the shaded photovoltaic panel will be reduced or the photovoltaic panel cannot generate electricity, so that the state of the partially covered panel assembly in the whole header box system is changed from the power station state to the load state, and the shielded portion of the assembly is connected in parallel with each other through the header box, so that the current flows backwards, the output power of the header box is influenced, the solar panel is heated seriously, and finally the shielded portion of the solar panel is burned out.
At present, a method generally adopted for solving the hot spot effect of the solar cell is to connect a bypass diode in parallel at the output end of a cell module, but the energy consumed by the diode is larger and the probability of failure is higher, therefore, when the hot spot effect or other failures occur to the photovoltaic equipment, the failed photovoltaic equipment can affect the whole photovoltaic power station, and the whole system is in a paralysis state due to the disorder of the system when the failure occurs seriously, and the control system of the distributed photovoltaic power station at present can not achieve the purpose of timely cutting off and isolating when a certain photovoltaic equipment fails, and the failed equipment is forced to exit the whole photovoltaic system, so that the whole photovoltaic system can not normally operate, and the difficulty of eliminating the failure is increased due to the conflict caused by an initial failure, and the failure equipment can not be cut off in time when the failure occurs, so that the corresponding equipment is seriously damaged, thereby improving the maintenance cost and economic loss of the photovoltaic equipment.
Referring to fig. 1 to 5, a specific implementation of this embodiment is shown, in this embodiment, the steady state of the operation of the photovoltaic device is monitored in a circulating manner to perform a judgment, so that the failed photovoltaic device is automatically detected in time and a corresponding cut-off and isolation measure is made, the failed photovoltaic device is forced to stop operating, and further confirmation is made based on the current dispersion rate, and the failed photovoltaic device can be cut off and isolated to the outside of the whole system quickly when a certain group of strings fails, so that the normal operation of other devices is ensured, adverse effects on the whole photovoltaic system are avoided, a forced regulation and control operation on the failed photovoltaic device is achieved, the normal operation of the whole photovoltaic power station is ensured, and the damage to the photovoltaic device due to the long-term existence of the failure is reduced.
Referring to fig. 2, the present embodiment is applied to a distributed photovoltaic power station, where the photovoltaic power station is used as a main body of a total power generation device, the total electric energy output by the photovoltaic power station may be self-used by a user, and the surplus electric energy is used for surfing the internet, where the user refers to various devices that can directly use direct current as electric energy supply, such as a photovoltaic street lamp, or a photovoltaic device constructed in a current village and town, the generated electric energy is directly used for household electricity, the photovoltaic power station is composed of a photovoltaic group a, a photovoltaic group B, \ 8230, and a photovoltaic group N, each photovoltaic group is composed of a separate combiner box, i.e., a dc combiner box of a photovoltaic system, and includes a photovoltaic device a, a photovoltaic device B, \\ 8230, and a photovoltaic device N, the positions of each photovoltaic device are different, the output ends of all the photovoltaic devices are connected and combined to a corresponding combiner box through a transmission bus, and the plurality of combiner boxes can transmit the current to a dc distribution cabinet according to a selection, or transmit to an ac distribution cabinet through a grid-connected inverter for grid connection.
In the method for regulating and controlling the faults of the distributed photovoltaic power station provided by this embodiment, under the equipment composition structure formed in fig. 2, a weighted average value M of the string current dispersion rates of the photovoltaic power station groups is first determined, in any time period T, whether the dispersion rate corresponding to the photovoltaic power station is within a range of a standard dispersion rate or not is determined, if the dispersion rate is within the range of the standard dispersion rate, it can be determined that the whole photovoltaic power station is in a stable operation state, no fault occurs in a branch circuit included under the photovoltaic power station, and if the dispersion rate is outside the range of the standard dispersion rate, it is determined that a certain photovoltaic group or a plurality of photovoltaic groups therein have a fault phenomenon, at this time, the dispersion rate needs to be calculated for all the photovoltaic groups, and whether each photovoltaic group has a fault or not is determined according to the dispersion rate.
Referring to fig. 1, a method for regulating a fault of a distributed photovoltaic power station includes the following steps:
s1, obtaining an average value D of a plurality of combiner box group current of a photovoltaic power station in a time period T;
the photovoltaic power station comprises a plurality of combiner boxes, each combiner box is provided with a corresponding string current discrete rate, and in the step, the string current discrete rate of each combiner box can be calculated by obtaining the average value of the string currents of all the combiner boxes in a time period T and according to a corresponding formula.
As an exemplary further description, it is assumed that the photovoltaic power station in this embodiment has N photovoltaic groups, and each photovoltaic group is also correspondingly provided with a junction box, at this time, the number of the junction boxes in the whole photovoltaic power station is at least N, and the group string current value corresponding to each junction box is set as
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、…、
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And the average value D of the current of the plurality of combiner box groups can be calculated by a formula:
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in the above formula, A and B respectively represent the corresponding labels of the photovoltaic groups, N represents the Nth photovoltaic group,
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representing the combiner boxes corresponding to the photovoltaic groups.
S2, calculating a weighted average M of the photovoltaic power station group current dispersion rate in the time period T according to the average D;
Figure DEST_PATH_IMAGE022
in the above-mentioned formula, the compound has the following structure,
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represents the average of several combiner box group current during the time period T,
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and the standard deviation of the output current of the photovoltaic power station in the T time period.
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In the above formula, the first and second carbon atoms are,
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for the photovoltaic power station in the T time period
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The output current of each photovoltaic group, N is the number of photovoltaic groups in the photovoltaic power station.
In step S2, a weighted average M of the string current dispersion rate of the photovoltaic power station group in the time period T is calculated according to the average D, and the specific process includes the following steps:
s21, dividing the time period T into a plurality of moments
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、…、
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S22, acquiring a plurality of moments
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、…、
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The current value of the group string corresponding to the next certain header box
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、…、
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S23, according to the string current value
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、…、
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Calculating the average current value of the string at the current moment
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According to the known parameters, the embodiment takes one of the several combiner boxes as an example, and the average current value of the combiner box at the current moment is completed through the following formula
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The calculation of (2):
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in the above-mentioned formula, the compound has the following structure,
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the number of divided time instants within the time period T,
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is a first
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And the current value of the group string corresponding to the time combiner box.
S24, average current value according to string
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Calculating the group string current discrete rate Q at the moment t;
according to the known parameters, the formula for calculating the string current dispersion ratio Q at the time t is as follows:
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in the above-mentioned formula, the compound has the following structure,
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and t is the standard deviation of the current of the combiner box set at the moment t, and t is the acquisition time point of the current of the combiner box set.
Accordingly, at time t:
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in the above-mentioned formula, the compound has the following structure,
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for the time t the combiner box is
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The current of the battery string, N, is the number of the battery strings of the combiner box.
S25, according to the time
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、…、
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Corresponding string current dispersion ratio
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、…、
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Calculating a weighted average value M;
as can be seen from the above calculation of the string current dispersion ratio of a single combiner box at time T, the average current value of the combiner box at several times in the time period T
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Corresponds to a group string current dispersion ratio with respect to time of day
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、…、
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Corresponding group string currentThe dispersion ratios are respectively
Figure 442048DEST_PATH_IMAGE011
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、…、
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And the average string current dispersion ratio corresponding to the combiner box is:
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according to the above content of the embodiment, the photovoltaic power station is composed of a plurality of photovoltaic groups, the combiner boxes under each corresponding photovoltaic group can be equally divided into a plurality of moments in the time period T, and the average group string current dispersion rate corresponding to each combiner box can be obtained by repeating the above calculation
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Thus, by derivation, the weighted average M is calculated by the following equation:
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in the above-mentioned formula, the compound has the following structure,
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is shown as
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Average string current dispersion rate corresponding to each combiner box.
According to the embodiment, the time period T is divided at a plurality of moments, the group string current dispersion rate at the moment T is obtained again through the average current value corresponding to each moment on the basis of the known average value, the weighted average value M is obtained through formula calculation, so that the accurate value of the photovoltaic power station to the current dispersion rate at the time period T can be improved, the error of the value is further reduced, meanwhile, the accuracy of judging whether the photovoltaic power station is in a stable operation state is improved, meanwhile, the phenomenon of misjudgment can be further avoided, and the timeliness and the reliability of regulation and control when the photovoltaic power station fails again are enhanced.
S3, judging whether the photovoltaic power station is in a stable operation state or not according to the standard discrete rate threshold value P;
if the weighted average value M is not more than the standard dispersion rate threshold value P, the photovoltaic power station is in a stable operation state, the step S1 is returned, and the next time period T +1 is judged again;
if the weighted average value M is larger than the standard dispersion rate threshold value P, the photovoltaic power station breaks down, and the step S4 is carried out;
here, the value range of the standard dispersion rate threshold value P is 0% -10%, and if the weighted average value M is within 0% -10%, it indicates that the photovoltaic power station operates stably, and the whole system does not have any fault.
S4, acquiring a working current value G of each group of strings corresponding to a plurality of photovoltaic groups in a time period T;
each photovoltaic group is connected with a corresponding collection flow box, in the process, the working current of each group of strings in the photovoltaic group is detected by the Hall sensor, the Hall sensor is based on a magnetic balance type Hall principle, namely a closed loop principle, the magnetic flux generated by the primary side current is concentrated in a magnetic circuit through a high-quality magnetic core, the Hall element is fixed in an air gap to detect the magnetic flux, and the reverse compensation current is output through a multi-turn coil wound on the magnetic core and used for offsetting the magnetic flux generated by the primary side current, so that the magnetic flux in the magnetic circuit is always kept to be zero. The differential signal is processed by the operational amplifier to output a current signal, and the triodes T1 and T2 are selectively conducted according to different directions of the output current. The absolute value of the output current of the triode is reduced in proportion to the string current, so that the Hall sensor can accurately reflect the size and the change condition of the string current. A precision resistor is connected between the current output end of the triode and the ground, an output current signal can be converted into a voltage signal, the voltage signal can be conveniently sampled and output by matching with an AD converter, and as further disclosure, the structure of the Hall sensor is shown in figure 3.
S5, calculating a string current discrete rate H of each photovoltaic group according to the working current value G;
in step S5, a string current discrete rate H of each photovoltaic group is calculated according to the working current value G, and the specific process includes the following steps:
s51, determining the maximum output voltage effective value of a single group string in each photovoltaic group
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And maximum output current effective value
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Because the power generation capacity of the photovoltaic equipment is directly influenced by the number of photovoltaic panels and the photoelectric conversion efficiency, in a group string, particularly a distributed photovoltaic power station which is relatively dispersed, the number of photovoltaic panels installed on the photovoltaic equipment is also inconsistent, and this phenomenon tends to cause that the current output by each group string is unequal, and similarly, the photovoltaic panels in different positions or orientations are also influenced by the photoelectric conversion efficiency, and at this time, the output current of a group string is also unequal.
In step S51, the maximum output voltage of the string is significant
Figure 211814DEST_PATH_IMAGE015
And maximum output current effective value
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The method is characterized in that an electric energy meter is adopted for measurement, namely, a time period is set as a sampling period, the sampling times of output voltage and current in the sampling period are set, and the maximum effective values of the output voltage and the current in the period and the average voltage and current values in the period can be obtained through calculation.
For example, 5s is set as a sampling period, the output voltage and current of the string are sampled at least 10 times within five seconds, and the sampled voltage values are respectively set as:
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and the current values are respectively set as:
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maximum output voltage
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Has effective values of:
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maximum output current
Figure 942004DEST_PATH_IMAGE016
Has effective values of:
Figure DEST_PATH_IMAGE038
by maximum output voltage effective value
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And maximum output current effective value
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The voltage-current conversion ratio of the string set in one sampling period can be calculated, and the stable output current value of the string set in one sampling period is determined according to the voltage-current conversion ratio.
S52, according to the maximum output voltage effective value
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And maximum output current effective value
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Calculating the voltage-current conversion ratio K of the single group string;
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s53, determining the stable output current A of the single string according to the voltage-current conversion ratio;
in the above step, the output current stabilized by the single string is a relative stable value in a sampling period, and is obtained by the current peak value and the voltage-current conversion ratio K in the sampling period, which is different from the average value, and the equilibrium state of the output current in the sampling period is more reflected relative to the average value.
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In the above formula, the first and second carbon atoms are,
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representing the peak value of the current in one sampling period,
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which represents the duration of the sampling period, in seconds,
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is a corresponding one of the time instants within one sampling period,
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s54, determining a working current G according to the stable output current A of the single string;
the working current value G of the group string in a sampling period at this time is the same as the value of the output current a by default, that is: g = a.
And S55, calculating the discrete rate H of the current group string current according to the working current value G and the standard deviation of the current group string current.
The calculation formula here is the same as step S24, namely:
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in the above formula, the first and second carbon atoms are,
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representing the standard deviation of the current set of string currents.
Note that, here, the calculation process of the dispersion ratio H is the same as that of step S24, and therefore, the dispersion ratio H is calculated for
Figure DEST_PATH_IMAGE046
The values of (a) are described in detail above, and detailed description is omitted here, and the same two parts can be referred to each other.
The group string current dispersion rate H calculation scheme provided by the embodiment can be used for more accurately taking a value of the working current value G, and can avoid the phenomenon that the value of the working current value is inaccurate due to specific factors, so that the interference factor of the specific factors to the inconsistency of the group string output currents is eliminated, meanwhile, the evaluation capacity of group string faults and conversion benefits can be improved, the photovoltaic power station is facilitated to regulate and control all the group strings, the quick judgment of the group strings with faults is guaranteed, and therefore the corresponding isolation cut-off operation is made.
This embodiment can be in wherein one or more group cluster under the condition that the trouble appears or the conversion benefit is lower, can be automatically with this group cluster quick isolation, avoid causing the influence to other group clusters to guaranteed whole photovoltaic power plant's continuation operation, and can be quick after the trouble elimination combine to the group cluster continue to put into use, consequently guaranteed photovoltaic power plant's maximum electric energy supply ability, provide the guarantee for the continuous output of electric energy.
S6, judging whether each photovoltaic group is in a stable operation state or not according to the standard discrete rate threshold value P;
if the string current dispersion rate H of the photovoltaic group is less than or equal to the standard dispersion rate threshold value P, the photovoltaic group is in a stable operation state, and after the photovoltaic group is marked as '0', a cyclic verification sequence is removed and the operation is finished;
if the string current discrete rate H of the group is larger than the standard discrete rate threshold value P, the photovoltaic group has a fault, and the step S7 is carried out after the photovoltaic group is marked as '1';
here, the value range of the standard discrete rate threshold P is 0% -5%, and if the current discrete rate H of the string is within 0% -5%, it indicates that the string is stable in overall operation, and the whole photovoltaic string has no fault.
When the step is executed, all photovoltaic groups form a cyclic verification sequence according to the number in a communication table, the communication table is stored in a local default mode, the number of all photovoltaic groups contained in one photovoltaic power station is recorded, data communication is established through an RS485 bus, and the essence of the method can be understood that the photovoltaic power station serves as a switchboard, all photovoltaic groups serve as extensions, and each photovoltaic group corresponds to a communication address.
And the photovoltaic groups in the communication table have a specific number set as Y, an upper computer contained in the photovoltaic power station is respectively in communication control connection with each photovoltaic group through an RS485 bus, the photovoltaic groups can receive control instructions sent by the photovoltaic power station, each communication address is also defined with a mark, all the photovoltaic groups can form a cyclic verification sequence according to the existing sequence of the mark, in the verification process, after one photovoltaic group is judged to be fault-free and marked as '0' through the dispersion rate, the server rejects the photovoltaic group marked as '0' into the verification cyclic sequence, then the next photovoltaic group is subjected to verification judgment of the dispersion rate, the dispersion rate corresponding to one or more photovoltaic groups exceeds a standard dispersion rate threshold value P, the server marks the corresponding photovoltaic group as '1' and generates a fault record, and the server makes a corresponding operation instruction.
The method comprises the steps that a circulation verification sequence is adopted to cover all photovoltaic groups under a photovoltaic power station, after one round of calculation dispersion rate is executed and corresponding judgment is made, the photovoltaic groups can be removed when no fault exists, then, the next photovoltaic group is continuously calculated and judged, the circulation can reduce the data calculation load of a large number of photovoltaic groups, each time one calculation judgment unit is reduced, the calculation load corresponding to a server is reduced, the judgment accuracy of the photovoltaic groups with faults is improved, and meanwhile, the calculation cost and the calculation requirement of equipment can be reduced.
S7, sending a delay unloading instruction to the photovoltaic group marked as '1' and isolating;
in step S7, a delayed unloading instruction is issued to the photovoltaic group marked with "1" and isolation is performed, and the specific process includes the following steps:
s71, detecting working currents of a plurality of groups of strings in the photovoltaic group marked as '1';
if the output current of a certain group of strings is detected to be 0 or a negative value, the solid-state relays on each group of strings are controlled to be immediately switched off through the server, the group of strings are isolated, the isolation time t is set, and the switching-off times are recorded as 1;
the photovoltaic group comprises a plurality of photovoltaic devices, each photovoltaic device is considered as a group string unit, a solid-state relay is arranged at the output end of each group string to control the on-off state, so that the purpose of isolating the group string is achieved, and when the working current of each group string is detected, the specific numerical value of the output current can be detected through the Hall sensor.
S72, circularly detecting the working current of the next string group;
if the output current of a certain group of strings is detected to be 0 or negative again, the same operation as the step S71 is performed;
if not, continuously detecting the working current of the rest group strings until a detection cycle is completed, wherein the detection cycle refers to the detection of the working current of the photovoltaic equipment (namely the group strings) contained in one photovoltaic group, and the detection of the last group string by the first group string forms a detection cycle;
s73, after the isolation time T is exceeded, the server controls the solid-state relay in the off state to be closed again, and the working current is detected again;
if the output current of the group of strings is normal, clearing the disconnection times and removing the isolation limitation;
if the output current of the series is 0 or a negative value, the solid-state relay is disconnected again, the isolation time t is set, the disconnection times are recorded as 2, and the step S72 is entered for circulation;
s74, acquiring a disconnection time record of each group string and judging whether the group string is removed or not according to a threshold value;
if the record of the number of times of disconnection is greater than or equal to 3, the string of the group is removed from the photovoltaic group, complete removal is achieved by controlling the disconnection of the solid-state relay through the server, the disconnection is complete disconnection at the moment, reclosing is not achieved after isolation is finished, reclosing can be achieved if the disconnection number record is cleared after overhaul and fault elimination of workers are needed, and the string of the group is put into use again.
Meanwhile, the group of strings are not detected any more, the group of strings are completely removed for use, and the embodiment can detect the working current of all the group strings covered by each photovoltaic group, so that when the corresponding photovoltaic group is judged to have a fault, the fault can be detected and determined again, and therefore the faulted photovoltaic equipment can be accurately positioned, and when a certain photovoltaic equipment has a hot spot effect, the certain photovoltaic equipment can be timely cut off and removed from the whole photovoltaic power station system, so that the normal operation of other photovoltaic groups is ensured, and the influence of the fault on the photovoltaic power station is reduced.
Specifically, in the present embodiment, the working current of each string of the photovoltaic set is less than 10A, and the current cannot be a negative value. And if the working current of a certain group of strings is judged to be more than 10A or less than or equal to 0 at a certain moment, judging that the group of strings has a fault condition. The failure may be caused by a recoverable condition, such as a partial photovoltaic panel being blocked by a cloud layer or a fallen leaf, or a bird stopping, or an unrecoverable condition, such as a damaged battery assembly of one or more photovoltaic panels in the string.
Once a fault condition is detected, a control signal is given to shut off a solid-state relay where a fault group string is located, then time delay processing is carried out, whether the fault occurs or not is judged again, if the fault is eliminated within 3 times of sampling, the fault is judged to be a short-time recoverable fault, the photovoltaic equipment works normally, fault information is cleared immediately, and the group string is normally put into operation; if the fault still exists, the fault is judged to be not the condition of self recovery in a short period, and the group of strings are completely cut off, so that the aims of protecting the photovoltaic panel and reducing the accident rate are fulfilled.
More excellent, the step of detecting the string with the output current of 0 or a negative value for three times can avoid misjudgment as a hot spot effect caused by shielding of instantaneous or temporary external environment factors, for example, shielding of movable objects such as black clouds, flyers or personnel can cause the hot spot effect of a photovoltaic panel, repeated cyclic detection and judgment can ensure that the photovoltaic device cannot cause any influence on the whole photovoltaic power station system in the isolation time, and can isolate the photovoltaic device in time, meanwhile, the secondary detection can avoid the misjudgment phenomenon, each string exceeds the isolation time, a new round of detection is immediately carried out, and the string is timely put into use when no fault is confirmed, so that the electric energy output efficiency of the whole photovoltaic power station is ensured, the effect of rechecking can be achieved by further detection, further, complete removal of the failed photovoltaic device is improved, and the operation safety of the whole photovoltaic power station is improved.
S8, removing the isolated photovoltaic module and sending a string fault command to the terminal; when the server obtains the group string information with faults through the judgment of the step S7, the group string is thoroughly removed from the photovoltaic power station, meanwhile, a group string fault command is sent to the terminal in a limited or wireless mode, and the fault information comprising the combiner box number and the battery group string number is given out, so that the position of the fault can be timely and accurately positioned by a worker, the arrangement of maintenance and inspection work can be rapidly made, the maintenance efficiency of the fault is improved, and the stable operation of the photovoltaic power station is guaranteed.
The operation stability of the photovoltaic equipment is monitored in a circulating mode to judge, the failed photovoltaic equipment is detected automatically in time and corresponding cut-off isolation measures are taken, the failed photovoltaic equipment is forced to stop operating, further confirmation is made based on the current dispersion rate, the photovoltaic equipment can be cut off and isolated outside the whole system when a certain group of strings fails, normal operation of other equipment is guaranteed, adverse effects on the whole photovoltaic system are avoided, forced regulation and control operation on the failed photovoltaic equipment is achieved, normal operation of the whole photovoltaic power station is guaranteed, and damage to the photovoltaic equipment due to long-term existence of faults is reduced.
Corresponding to the fault regulation and control method provided in the foregoing embodiment, this embodiment further provides a system of the fault regulation and control method, and since the fault regulation and control system provided in this embodiment corresponds to the fault regulation and control method provided in the foregoing embodiment, the implementation of the foregoing fault regulation and control method is also applicable to the fault regulation and control system provided in this embodiment, and will not be described in detail in this embodiment.
Referring to fig. 4, it is a block diagram of a fault control system provided in this embodiment, where the fault control system includes:
the first acquisition module 10 is used for acquiring an average value D of the current of a plurality of combiner box groups of the photovoltaic power station in a time period T;
the first calculating module 20 is used for calculating a weighted average value M of the photovoltaic power station group string current discrete rate in the time period T according to the average value D;
the first judging module 30, the first judging module 30 is used for judging whether the photovoltaic power station is in a stable operation state according to the standard discrete rate threshold value P;
the second obtaining module 40 is configured to obtain a working current value G of each group of strings corresponding to a plurality of photovoltaic groups in the time period T;
the second calculating module 50 is configured to calculate a group string current discrete rate H of each photovoltaic group according to the working current value G;
the second judging module 60 is configured to judge whether each photovoltaic group is in a stable operation state according to the standard discrete rate threshold P;
the isolation module 70, the isolation module 70 is configured to issue a delayed unloading instruction to the photovoltaic group marked with "1" and perform isolation;
and a removing module 80, wherein the removing module 80 is used for removing the isolated photovoltaic assembly and sending a group string fault command to the terminal.
It should be noted that, in the system provided in the foregoing embodiment, when the functions of the system are implemented, only the division of the functional modules is illustrated, and in practical applications, the functions may be distributed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules, so as to complete all or part of the functions described above. In addition, the system and method embodiments provided by the above embodiments belong to the same concept, and specific implementation processes thereof are described in the method embodiments for details, which are not described herein again.
The fault regulation and control system of this embodiment can be under the condition that one or more group cluster therein broke down or the conversion benefit is lower, can be automatically with this group cluster quick isolation, avoid causing the influence to other group clusters to guaranteed whole photovoltaic power plant's continuation operation, and can be quick combination continue to put into use to the group cluster after the trouble is eliminated, consequently guaranteed photovoltaic power plant's maximum electric energy supply ability, provide the guarantee for the continuous output of electric energy.
The embodiment also provides a computer device, and fig. 5 is a block diagram of an internal structure of the computer device in the present application. As shown in fig. 5, the computer apparatus includes a processor, a memory, a network interface, an input device, and a display screen, which are connected through a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory includes a storage medium and an internal memory. The storage medium may be a nonvolatile storage medium or a volatile storage medium. The storage medium stores an operating system and may also store computer readable instructions that, when executed by the processor, may cause the processor to implement a fault regulation method. The internal memory provides an environment for the operating system and execution of computer readable instructions in the storage medium. The internal memory may also have computer readable instructions stored thereon that, when executed by the processor, cause the processor to perform a fault regulation method. The network interface of the computer device is used for communicating with an external server through a network connection. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on the shell of the computer equipment, an external keyboard, a touch pad or a mouse and the like.
In one embodiment, a computer device is provided, which includes a memory, a processor, and computer readable instructions (e.g., a computer program) stored in the memory and executable on the processor, wherein the processor executes the computer readable instructions to implement the steps of the fault management method in the above embodiments, such as the steps S1 to S8 shown in fig. 1 and other extensions of the method and related steps. Alternatively, the processor, when executing the computer readable instructions, implements the functions of the modules/units of the fault regulation system in the above embodiments, such as the functions of modules 10 to 80 shown in fig. 4. To avoid repetition, further description is omitted here.
The processor may be a Central Processing Unit (CPU), other general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, etc. The general purpose processor may be a microprocessor or the processor may be any conventional processor or the like, the processor being the control center of the computer device and various interfaces and lines connecting the various parts of the overall computer device.
The memory may be used to store computer readable instructions and/or modules, and the processor may implement various functions of the computer apparatus by executing or executing the computer readable instructions and/or modules stored in the memory and invoking data stored in the memory. The memory may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required by at least one function (such as a sound playing function, an image playing function, etc.), and the like; the storage data area may store data (such as audio data, video data, etc.) created according to the use of the cellular phone, etc.
The memory may be integrated in the processor or may be provided separately from the processor.
Those skilled in the art will appreciate that the architecture shown in fig. 5 is merely a block diagram of some of the structures associated with the disclosed aspects and is not intended to limit the computing devices to which the disclosed aspects apply, as particular computing devices may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.
The above-mentioned serial numbers of the embodiments of the present application are merely for description and do not represent the merits of the embodiments. Through the description of the foregoing embodiments, it is clear to those skilled in the art that the method of the foregoing embodiments may be implemented by software plus a necessary general hardware platform, and certainly may also be implemented by hardware, but in many cases, the former is a better implementation. Based on such understanding, the technical solution of the present application may be substantially or partially embodied in the form of a software product, which is stored in a storage medium (e.g., ROM/RAM, magnetic disk, optical disk) as described above and includes instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, or a network device) to execute the method according to the embodiments of the present application.
The foregoing embodiments have described the present invention in detail, and the principle and embodiments of the present invention are explained by applying specific examples herein, and the descriptions of the foregoing embodiments are only used to help understand the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims (9)

1. A fault regulation and control method of a distributed photovoltaic power station is characterized by comprising the following steps:
s1, obtaining an average value D of a plurality of combiner box group current of a photovoltaic power station in a time period T;
s2, calculating a weighted average M of the photovoltaic power station group current dispersion rate in the time period T according to the average D;
s3, judging whether the photovoltaic power station is in a stable operation state or not according to the standard discrete rate threshold value P;
if the weighted average value M is not more than the standard dispersion rate threshold value P, the photovoltaic power station is in a stable operation state, the step S1 is returned, and the next time period T +1 is judged again;
if the weighted average value M is larger than the standard dispersion rate threshold value P, the photovoltaic power station breaks down, and the step S4 is carried out;
s4, acquiring a working current value G of each group of strings corresponding to a plurality of photovoltaic groups in a time period T;
s5, calculating a string current discrete rate H of each photovoltaic group according to the working current value G;
s6, judging whether each photovoltaic group is in a stable operation state or not according to the standard discrete rate threshold value P;
if the string current dispersion rate H of the photovoltaic group is less than or equal to the standard dispersion rate threshold value P, the photovoltaic group is in a stable operation state, and after the photovoltaic group is marked as '0', a cyclic verification sequence is removed and the operation is finished;
if the string current discrete rate H of the group is larger than the standard discrete rate threshold value P, the photovoltaic group has a fault, and the step S7 is carried out after the photovoltaic group is marked as '1';
s7, sending a delay unloading instruction to the photovoltaic group marked as '1' and isolating;
and S8, removing the isolated photovoltaic module and sending a group string fault command to the terminal.
2. The fault regulation method of claim 1, wherein: in step S2, a weighted average M of the string current dispersion rate of the photovoltaic power station group in the time period T is calculated according to the average D, and the specific process includes the following steps:
s21, dividing the time period T into a plurality of moments
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Figure 59734DEST_PATH_IMAGE006
、…、
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S22, acquiring a plurality of moments
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、…、
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The current value of the group string corresponding to the next header box
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、…、
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S23, according to the string current value of the group
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Figure 539202DEST_PATH_IMAGE014
、…、
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Calculating the average current value of the string at the current moment
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S24, average current value according to string
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Calculating the group string current discrete rate Q at the moment t;
s25, according to the time
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、…、
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Corresponding string current dispersion ratio
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、…、
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A weighted average M is calculated.
3. The fault regulation method of claim 1, wherein: in step S5, a string current discrete rate H of each photovoltaic group is calculated according to the working current value G, and the specific process includes the following steps:
s51, determining the maximum output voltage effective value of a single group string in each photovoltaic group
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And maximum output current effective value
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S52, according to the maximum output voltage effective value
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And the maximum output current hasEffective value
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Calculating the voltage-current conversion ratio K of the single string;
s53, determining the stable output current A of the single string according to the voltage-current conversion ratio;
s54, determining a working current G according to the stable output current A of the single string;
and S55, calculating the string current dispersion rate H according to the working current value G and the standard deviation of the current string current.
4. The fault regulation method of claim 1, wherein: in step S7, a delayed unloading instruction is issued to the photovoltaic group marked with "1" and isolation is performed, and the specific process includes the following steps:
s71, detecting working currents of a plurality of groups of strings in the photovoltaic group marked as '1';
if the output current of a certain group of strings is detected to be 0 or a negative value, the solid-state relays on each group of strings are controlled to be immediately switched off through the server, the group of strings are isolated, the isolation time t is set, and the switching-off times are recorded as 1;
s72, circularly detecting the working current of the next string group;
if the output current of a certain group of strings is detected to be 0 or negative again, the same operation as the step S71 is performed;
if not, continuously detecting the working current of the rest strings until completing a detection cycle;
s73, after the isolation time T is exceeded, the server controls the solid-state relay in the off state to be closed again, and the working current is detected again;
if the output current of the group of strings is normal, clearing the disconnection times and removing the isolation limitation;
if the output current of the group of strings is 0 or a negative value, the solid-state relay is disconnected again, the isolation time t is set, the disconnection times are recorded as 2, and the step S72 is executed for circulation;
and S74, acquiring the disconnection times record of each group string and judging whether to remove the group string according to a threshold value.
5. The fault regulation method of claim 1, wherein: in step S3, the range of the standard discrete rate threshold P is 0% to 10%.
6. The fault regulation method of claim 1, wherein: in step S6, the range of the standard discrete rate threshold P is 0% to 5%.
7. The fault regulation method of claim 1, wherein: in step S8, the terminal includes a PC, a notebook, a tablet, or a mobile phone.
8. A system for implementing the fault regulation method of any one of claims 1 to 7, characterized in that the system comprises:
the device comprises a first acquisition module (10), wherein the first acquisition module (10) is used for acquiring an average value D of a plurality of combiner box group string currents of the photovoltaic power station in a time period T;
a first calculation module (20), wherein the first calculation module (20) is used for calculating a weighted average value M of the photovoltaic power station string current dispersion rate in the time period T according to the average value D;
the first judgment module (30) is used for judging whether the photovoltaic power station is in a stable operation state or not according to a standard dispersion rate threshold value P;
the second acquisition module (40) is used for acquiring the working current value G of each group string corresponding to a plurality of photovoltaic groups in a time period T;
a second calculation module (50), wherein the second calculation module (50) is used for calculating a string current dispersion rate H of each photovoltaic group according to the working current value G;
the second judgment module (60) is used for judging whether each photovoltaic group is in a stable operation state or not according to the standard discrete rate threshold value P;
an isolation module (70), wherein the isolation module (70) is used for sending a delay unloading instruction to the photovoltaic group marked as '1' and isolating the photovoltaic group;
a removal module (80), the removal module (80) being configured to remove the isolated photovoltaic module and send a string fault command to the terminal.
9. A computer device comprising a processor and a memory for storing a computer program which, when executed by the processor, implements a fault regulation method as claimed in any one of claims 1 to 7.
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