CN111934618A - Photovoltaic branch and inverter efficiency loss evaluation method in photovoltaic power station - Google Patents

Photovoltaic branch and inverter efficiency loss evaluation method in photovoltaic power station Download PDF

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CN111934618A
CN111934618A CN202010811606.9A CN202010811606A CN111934618A CN 111934618 A CN111934618 A CN 111934618A CN 202010811606 A CN202010811606 A CN 202010811606A CN 111934618 A CN111934618 A CN 111934618A
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inverter
fault
photovoltaic
branch
evaluation
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CN111934618B (en
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汪海宁
王晓舟
倪玮晨
王建
张健
苏建徽
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State Grid Tianjin Electric Power Co Ltd
Hefei University of Technology
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State Grid Tianjin Electric Power Co Ltd
Hefei University of Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B10/00—Integration of renewable energy sources in buildings
    • Y02B10/10—Photovoltaic [PV]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/70—Smart grids as climate change mitigation technology in the energy generation sector
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications

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Abstract

The invention discloses an efficiency loss evaluation method of a photovoltaic branch and an inverter in a photovoltaic power station, which takes the typical fault power loss of the photovoltaic branch and the inverter as evaluation indexes to establish an evaluation index system; calculating the ratio of the fault power loss of the two; determining subjective evaluation weights of various faults of the two types of the faults by using a 3-scale analytic hierarchy process, and determining objective evaluation weights of various faults of the two types of the faults by using a complex correlation coefficient method; linearly combining the subjective and objective evaluation weights to obtain a comprehensive evaluation weight index; the comprehensive evaluation weight is used as an efficiency loss evaluation base number, and fault efficiency loss evaluation indexes of the fault information and the power data are constructed in combination; and evaluating the efficiency loss degree of the two faults according to the fault information and the power data. The method can evaluate the efficiency loss of the photovoltaic power station and the photovoltaic power station when the photovoltaic power station and the photovoltaic power station fail, so that the efficiency loss degree and the severity of the failure of the photovoltaic power station and the photovoltaic power station can be measured, and a reference is provided for the operation and maintenance of the photovoltaic power station.

Description

Photovoltaic branch and inverter efficiency loss evaluation method in photovoltaic power station
Technical Field
The invention relates to a photovoltaic branch and inverter efficiency loss evaluation method in a photovoltaic power station, and belongs to the technical field of operation, maintenance and monitoring of photovoltaic power stations.
Background
In a photovoltaic power station, a photovoltaic branch and an inverter are two most central devices. The performance of the photovoltaic branch and the inverter directly determines the performance of the whole photovoltaic power station, so that the performance evaluation of the two devices is necessary.
Currently, in the evaluation of photovoltaic power stations, the following categories can be assigned:
(1) and evaluating the economic benefit of the photovoltaic power station. Due to commercialization of photovoltaic power generation, most power stations focus on economic benefits, and therefore a lot of scholars and experts do considerable work on the aspect of economic benefit evaluation of photovoltaic power stations;
(2) and evaluating the efficiency of the photovoltaic power station by using the system efficiency PR value. The time scale of the evaluation method is large, generally, a month or a year is taken as a time unit, the efficiency of the power station system is simply measured by the ratio of the generated energy to the received irradiation energy in a period of time, and the efficiency loss caused by the faults of components such as a photovoltaic branch circuit, an inverter and the like can be covered;
(3) emphasis is placed on the evaluation of the performance of the plant during normal operation. Most of evaluation methods start from the whole power station, and select factors such as weather and geographic positions which affect the efficiency of the power station as evaluation indexes, without considering the efficiency loss when the photovoltaic branch and the inverter are in a fault condition;
(4) in the combined weighted evaluation method, an evaluation method based on an entropy weight method is often used. The entropy weight method is weighted according to the discrete degree of a certain index, the calculation process is simple, the discrete degree is based on index data, the larger the discrete degree is, the larger the influence of the index on comprehensive evaluation is, and the weighted value is higher. However, if the collected sample quality is poor and the data fluctuation is large, the index may be given too low weight and be covered by other indexes, which deviates from the actual value.
The photovoltaic branch and the inverter are two most important devices in a photovoltaic power station, the current evaluation method takes the whole power station as an object, efficiency evaluation of the two devices is not careful, and especially research on efficiency loss evaluation under the condition that the photovoltaic branch and the inverter are in failure is less. Therefore, it is an urgent problem to establish an evaluation method for the efficiency loss degree of photovoltaic branches and inverters in a photovoltaic power station during failure.
Disclosure of Invention
The invention aims to fill the defects of the prior art in the aspect of evaluating the efficiency loss of a photovoltaic branch and an inverter under the fault condition, and provides a method for evaluating the efficiency loss of the photovoltaic branch and the inverter in a photovoltaic power station, so that the efficiency loss evaluation indexes of the photovoltaic branch and the inverter under the fault condition can be constructed, the efficiency loss degree and the fault severity of the photovoltaic branch and the inverter under the fault condition can be measured, and a reference is provided for the operation and maintenance of the photovoltaic power station.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to a method for evaluating the efficiency loss of a photovoltaic branch and an inverter in a photovoltaic power station, which is characterized by comprising the following steps of:
step 1, taking typical fault power losses of a photovoltaic branch and an inverter as evaluation indexes, and establishing a fault efficiency loss evaluation index system of the photovoltaic branch and the inverter;
step 2, obtaining the power loss ratio delta eta of the photovoltaic branch circuit caused by the ith fault type of the photovoltaic branch circuit by using the formula (1)pv(i)：
Figure BDA0002631162750000021
In the formula (1), Δ Ppv(i)To representIncreased power loss of the photovoltaic branch upon occurrence of the ith fault type; delta PstationRepresenting the loss of the photovoltaic power station in normal operation;
the power loss ratio delta eta of the inverter caused by the j fault type of the inverter is obtained by the formula (2)inv(j)：
Figure BDA0002631162750000022
In the formula (2), Δ Pinv(j)Indicating increased power loss of the inverter upon occurrence of the various jth fault types;
step 3, determining subjective evaluation weights W of various fault types of the photovoltaic branch and the inverter by using a 3-scale analytic hierarchy processpv(i)、Winv(j)(ii) a And the efficiency loss ratio delta eta is caused according to various fault types of the photovoltaic branch and the inverterpv(i)、Δηinv(j)Determining objective evaluation weight V of various fault types of photovoltaic branch and inverter by using complex correlation coefficient methodpv(i)、Vinv(j)；
Step 4, evaluating the main and objective efficiency loss evaluation weights W of the ith fault type of the photovoltaic branchpv(i)、Vpv(i)Linearly combining to obtain the comprehensive evaluation weight W of the ith fault efficiency loss of the photovoltaic branchzpv(i)；
Evaluating the main and objective performance loss evaluation weight W of the j fault type of the inverterinv(j)、Vinv(j)Linearly combining to obtain the j-th failure efficiency loss comprehensive evaluation weight W of the inverterzinv(j)；
Step 5, comprehensively evaluating the efficiency loss of each fault of the photovoltaic branchzpv(i)As a comprehensive evaluation base number, the photovoltaic branch fault efficiency evaluation index S is constructed by combining the photovoltaic branch fault information, the actual maximum power of the branch under the current environmental condition and the theoretical maximum power of the branch under the normal conditionpv；
Comprehensively evaluating the efficiency loss of each fault of the inverter by weight Wzinv(j)Combining inverter fault information and inverter direct current as a comprehensive evaluation baseConstructing an inverter fault efficiency evaluation index S by side average power and alternating current side average powerinv；
And 6, obtaining an efficiency loss evaluation index S when the photovoltaic branch and the inverter are in failure according to the failure information of the photovoltaic branch and the inverter and the power data in the step 5pv、SinvThe value of (c).
The efficiency loss evaluation method is also characterized in that the photovoltaic branch fault efficiency evaluation index S in the step 5 is obtained by using the formula (3)pv：
Figure BDA0002631162750000031
In the formula (3), NiRepresenting the number of the ith fault type assemblies in the photovoltaic branch for the fault information quantity of the photovoltaic branch; ppvRepresenting the actual maximum output power of the photovoltaic branch; pmpvRepresenting the theoretical maximum output power of the photovoltaic branch under the current irradiance and temperature; 1,2,. m; m represents the total number of the photovoltaic branch fault types;
obtaining an inverter fault efficiency evaluation index S by using the formula (4)inv：
Figure BDA0002631162750000032
In the formula (4), LjThe quantity of the inverter fault information represents whether the jth fault type of the inverter occurs or not, wherein the occurrence is 1 instead of 0;
Figure BDA0002631162750000033
represents the average power on the ac side of the inverter,
Figure BDA0002631162750000034
representing the average power of the direct current side of the inverter; 1,2, n; n represents the total number of inverter fault types.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention takes the power loss ratio caused by typical fault types of the photovoltaic branch and the inverter as an evaluation index, and provides a method for evaluating the efficiency loss degree of the photovoltaic branch and the inverter during the fault, so that operation and maintenance personnel of a photovoltaic power station can master the efficiency level of the photovoltaic branch and the inverter during normal operation and can also master the efficiency loss degree and the severity of the fault during the fault, and accordingly, whether shutdown maintenance is executed is decided;
2. in order to reflect the fault severity of a photovoltaic branch and an inverter in an efficiency loss evaluation index, a combined weighting method based on a 3-scale analytic hierarchy process and a complex correlation coefficient method is introduced, the weight is reasonably distributed for each fault of the photovoltaic branch and the inverter according to expert experience judgment and actual data, and the combined weight of the faults is used for measuring the fault severity, namely the greater the weight is, the more serious the weight is, so that the purpose of reflecting the fault severity is achieved;
3. the method takes the combined weight of the faults as a comprehensive evaluation base number, and simultaneously combines the fault information and the respective power data of the two to respectively construct the fault efficiency evaluation indexes of the two; the efficiency loss degree caused by the current fault is reflected by the power data, the severity of the current fault is reflected by the fault information and the fault combination weight, the defect that the existing evaluation method only focuses on the efficiency of the photovoltaic branch and the inverter but cannot reflect the severity of the fault is overcome, and the effect of comprehensively evaluating the efficiency loss and the severity of the fault of the photovoltaic branch and the inverter is achieved.
4. The invention can keep the actual photovoltaic branch and the inverter unchanged after determining the comprehensive evaluation cardinal number of each fault type of the photovoltaic branch and the inverter, and then can directly calculate the fault efficiency loss evaluation indexes of the photovoltaic branch and the inverter by only collecting the fault information of the photovoltaic branch and the inverter, the current power and the theoretical maximum power of the photovoltaic branch and the average power of the alternating current and direct current sides of the inverter.
Drawings
FIG. 1 is a flow chart of a performance loss assessment method of the present invention;
FIG. 2 is a topology diagram of a three-phase two-level inverter in the prior art;
FIG. 3 is a prior art single tube open circuit fault topology diagram of an inverter;
FIG. 4 is a topology diagram of an in-phase double-tube open-circuit fault of an inverter in the prior art;
FIG. 5 is a topology diagram of a double-tube open circuit of the same bridge of an inverter in the prior art;
FIG. 6 is a prior art inverter crossover double tube open circuit fault topology;
FIG. 7 is a comparison graph of different failure performance loss evaluation indexes of the photovoltaic branch circuit according to the present invention;
fig. 8 is a comparison graph of performance loss evaluation index curves for different faults under different loads of the inverter of the present invention.
Detailed Description
In this embodiment, a method for evaluating the efficiency loss of a photovoltaic branch and an inverter in a photovoltaic power station, especially a method for evaluating the efficiency loss of a photovoltaic branch and an inverter under a fault condition by using a pointer, as shown in fig. 1, includes the following specific steps:
step 1, taking typical fault power losses of the photovoltaic branch and the inverter as evaluation indexes, and establishing a fault efficiency loss evaluation index system of the photovoltaic branch and the inverter. For photovoltaic branches, the most frequent faults are concentrated at the component level, mainly including four categories: (1) open circuit failure of the component caused by the reasons of component interconnect soldering failure, breakage, etc.; (2) short circuit of the assembly caused by wiring error, insulation damage of assembly wiring and the like; (3) component mismatch caused by branch local shielding, hot spots, component overheating and the like; (4) the assembly ages. Therefore, the power loss caused by four fault types of open circuit of the component, short circuit of the component, mismatch of the component and aging of the component is used as the evaluation index of the efficiency loss of the photovoltaic branch fault, and X is respectively used1、X2、X3、X4Instead, when the photovoltaic branch fault type subscript i is 1,2,3,4, that is, m is 4;
for inverters, the most common faults occur concentrated on the power switching tubes. In the present embodiment, a three-phase two-level inverter is taken as an example, as shown in fig. 2, the open-circuit faults of the switching tubes mainly include two types: (1) the single power switch tube is in open circuit fault, namely one of 6 switch tubes is in open circuit,the topology is shown in FIG. 3; (2) the double-switch tube open-circuit fault can be divided into four power switch tube open-circuit fault types of an in-phase double-tube open-circuit type, an in-bridge arm double-tube open-circuit type (two upper tubes or two lower tubes) and a cross double-tube open-circuit type (namely one upper tube and one lower tube) according to the position of the switch tube, and the topologies of the double-switch tube open-circuit fault types are respectively shown in fig. 4, fig. 5 and fig. 6. Therefore, the power loss caused by four fault types of in-phase double-tube open circuit, same-bridge arm double-tube open circuit, cross double-tube fault and single-tube open circuit is used as the evaluation index of the fault efficiency loss of the inverter, and respectively F is used1、F2、F3、F4Instead, when the inverter fault type index j is 1,2,3,4, that is, n is 4;
step 2, carrying out Simulink simulation on four fault types of the photovoltaic branch, and subtracting the output power in normal state from the output power of the branch in fault state to obtain the open-circuit power loss delta P of the assemblypv(1)Component short circuit power loss Δ Ppv(2)Component mismatch power loss Δ Ppv(3)Component aging power loss Δ Ppv(4)Obtaining the power loss ratio delta eta of the photovoltaic branch circuit caused by the ith fault type of the photovoltaic branch circuit by using the formula (1)pv(i)：
Figure BDA0002631162750000051
In the formula (1), Δ PstationRepresenting the loss of the photovoltaic power plant during normal operation. The normal operation power loss of the power station is about 4 percent of the installed capacity, and the installed capacity is 200KWp, so the delta PstationThe specific power loss share of the photovoltaic branch is shown in table 1, 8 KW.
Table 1: power loss ratio of four faults of photovoltaic branch circuit
Type of failure X1 X2 X3 X4
Branch 1 6.25％ 6.1％ 1.625％ 2.78％
Branch 2 6.4％ 6.25％ 1.93％ 2.65％
Branch 3 6.53％ 6.35％ 1.95％ 3.93％
Simulink simulation is carried out on four fault types of the inverter, and the power loss in normal time and the power loss in fault time are differentiated to obtain the single-tube open-circuit power loss delta Pinv(1)In-phase double-tube open-circuit power loss delta Pinv(2)Same bridge arm double-tube open-circuit power loss delta Pinv(3)Cross double-tube open-circuit power loss delta Pinv(4)The power loss ratio delta eta of the inverter caused by the jth fault type of the inverter is obtained by the formula (2)inv(j)：
Figure BDA0002631162750000052
In the formula (2), Δ Pinv(j)Indicating increased power loss of the inverter upon the occurrence of the various jth fault types. Specifically, as shown in table 2.
Table 2: four fault power loss ratios of inverter
Type of failure F1 F2 F3 F4
100％ 25.73％ 15.46％ 11.55％ 2.69％
90% load 22.47％ 13.37％ 6.45％ 2.85％
70% load 19.83％ 6.75％ 5.629％ 2.75％
40% load 15.52％ 3.27％ 1.21％ 2.11％
Step 3, determining subjective evaluation weight indexes W of various fault types of the photovoltaic branch and the inverter by using a 3-scale analytic hierarchy processpv(i)、Winv(j)(ii) a Efficiency loss ratio delta eta caused by various fault types of photovoltaic branch and inverterpv(i)、Δηinv(j)Determining objective evaluation weight index V of various fault types of photovoltaic branch and inverter by using a complex correlation coefficient methodpv(i)、Vinv(j). The method comprises the following specific steps:
(1) the 3-scale analytic hierarchy process quantifies the influence value by comparing the influence strength between two factors, for example, n faults can be obtained by comparing every two faults2The influence value is used for constructing a judgment matrix A (a) for describing the influence among the n fault typeskl)n×n. The rule of values for the 3-scale analytic hierarchy process is shown in table 3.
Table 3: 3-Scale analytic hierarchy Process value rule
Factor k to factor l aklValue taking
Strong influence 1
Same influence 0
Weak influence -1
And then, according to the matrix A, the optimal transfer matrix B of A is obtained as the following formula (B)kl)n×n
Figure BDA0002631162750000061
Then, a complete consistency matrix C of the matrix A is solved according to the matrix B*
C*＝eB (4)
Finally, the weight is calculated by a square root method and then normalized, and the subjective weight of each fault can be obtained
Figure BDA0002631162750000071
Wherein the content of the first and second substances,
Figure BDA0002631162750000072
1) subjective weight determination method for four fault types of photovoltaic branch
The subjective effectiveness influence on the fault types is ranked as follows: x1＝X2＞X3＞X4
Constructing a judgment matrix:
Figure BDA0002631162750000073
obtaining an optimal transfer matrix:
Figure BDA0002631162750000074
solving a complete consistency matrix
Figure BDA0002631162750000075
Finally, the fault X is obtained1Subjective weight Wpv(1)0.31, failure X2Subjective weight of Wpv(2)0.31, failure X3Subjective weight Wpv(3)0.216, fault X4Subjective weight Wpv(4)＝0.166。
2) Subjective weight for determining four fault types of inverter
The subjective effectiveness influence on the fault types is ranked as follows: f1＞F2＞F3＞F4
Constructing a judgment matrix:
Figure BDA0002631162750000076
obtaining an optimal transfer matrix:
Figure BDA0002631162750000077
solving a complete consistency matrix
Figure BDA0002631162750000081
Finally, the fault F is obtained1Subjective weight Winv(1)0.35, fault F2Subjective weight Winv(2)0.272, fault F3Subjective weight Winv(3)0.212, fault F4Subjective weight Winv(4)＝0.165；
(2) The multiple correlation coefficient method assigns weights according to the correlation between the evaluation indexes. If m samples and n evaluation indexes are set, the original data matrix Y is (Y)kl)m×n. Then there is a correlation coefficient matrix Rn＝(rkl)n×nMatrix element rklIs determined by
Figure BDA0002631162750000082
So that the complex correlation coefficient of the index j is
Figure BDA0002631162750000083
Wherein r isl＝(r1(l),r2(l),...,rn-1(l))T，Rl→n-1And representing the correlation coefficient matrix after the ith column in the original data matrix Y is removed.
The objective weight of the final index j is
Figure BDA0002631162750000084
1) Determining objective weights of four fault types of photovoltaic branch
Original data matrix:
Figure BDA0002631162750000085
obtaining a correlation coefficient matrix:
Figure BDA0002631162750000086
the failure X is obtained according to the formula (7) and the formula (8)1Objective weight Vpv(1)0.213, failure X2Objective weight Vpv(2)0.218, fault X3Objective weight Vpv(3)0.28, fault X4Objective weight Vpv(4)＝0.289；
2) Determining objective weights of four fault types of inverter
Original data matrix:
Figure BDA0002631162750000091
obtaining a correlation coefficient matrix:
Figure BDA0002631162750000092
determining the fault F according to the equations (7) and (8)1Objective weight Vinv(1)0.242, fault F2Objective weight Vinv(2)0.235, failure F3Objective weight Vinv(3)0.245, failure F4Objective weight Vinv(4)＝0.277；
Step 4, evaluating the main and objective efficiency loss evaluation weights W of the ith fault type of the photovoltaic branchpv(i)、Vpv(i)Linearly combining to obtain the comprehensive evaluation weight W of the ith fault efficiency loss of the photovoltaic branchzpv(i). The 3-scale analytic hierarchy process represents the subjective actual engineering experience of engineering personnel in practice, the complex correlation coefficient process represents the actual development rule of objective things, and in order to enable the evaluation system to take both subjectivity and objectivity into consideration, the weighted values obtained by the two processes are linearly combined, as shown in the following formula
Wz＝αWj+βVj，j＝1,2,...,n (9)
Wherein, α ═ β ═ 0.5 represents half of the share of subjective opinion and objective fact, so that both objectivity and subjectivity can be achieved.
Substituting the main and objective weights of the four fault types of the photovoltaic branch into a formula (9), and obtaining comprehensive evaluation weights respectively as follows: component open circuit Wzpv(1)0.262, short-circuit of assembly Wzpv(2)0.264, component mismatch Wzpv(3)0.246, component aged Wzpv(3)And 0.227, namely, the photovoltaic branch fault efficiency loss comprehensive evaluation base.
Evaluating the main and objective performance loss evaluation weight W of the j fault type of the inverterinv(j)、Vinv(j)And linear combination is also carried out according to the formula (9), and the comprehensive evaluation weights of the j-th fault efficiency loss of the inverter are respectively obtained as follows: cophased double-tube open circuit Wzinv(1)0.296 double-tube open circuit W of same bridge armzinv(2)0.256 double tube crossing fault Wzinv(3)Single tube open circuit W (0.229)zinv(4)0.221, namely the comprehensive evaluation base of the fault performance loss of the inverter.
Step 5, comprehensively evaluating the efficiency loss of each fault of the photovoltaic branchzpv(i)As a comprehensive evaluation base number, combining the fault information of the photovoltaic branch circuit, the actual maximum power of the branch circuit under the current environmental condition and the branch circuitConstructing a photovoltaic branch fault efficiency evaluation index S according to the theoretical maximum power under normal conditionspv(ii) a Comprehensively evaluating the efficiency loss of each fault of the inverter by weight Wzinv(j)As a comprehensive evaluation base number, the inverter fault information, the average power of the direct current side of the inverter and the average power of the alternating current side of the inverter are combined to construct an inverter fault efficiency evaluation index Sinv；
6, calculating an efficiency loss evaluation index S when the specific photovoltaic branch and the specific inverter are in failure according to the failure information of the photovoltaic branch and the inverter and the power data in the step 5pv、Sinv。
In step 5, the comprehensive evaluation weight of the four fault types of the photovoltaic branch obtained in step 4 in step 1 is used as a comprehensive evaluation base number of the efficiency loss, and the severity of the photovoltaic branch fault and the degree of the efficiency loss caused by the fault are reflected by combining the fault information of the photovoltaic branch and the ratio of the current branch maximum power to the branch theoretical maximum power. Therefore, the photovoltaic branch fault efficiency evaluation index S is constructedpvIs composed of
Figure BDA0002631162750000101
In the formula (10), NiRepresenting the number of the ith fault type assemblies in the photovoltaic branch for the fault information quantity of the photovoltaic branch; ppvRepresenting the actual maximum output power of the photovoltaic branch; pmpvRepresenting the theoretical maximum output power of the photovoltaic branch under the current irradiance and temperature; 1,2,. m; and m represents the total number of the photovoltaic branch fault types.
Similarly, the comprehensive evaluation weight of the four fault types of the inverter obtained in step 4 in step 1 is used as a comprehensive evaluation base for performance loss, and the severity of the inverter fault and the degree of performance loss caused by the fault are reflected by combining the inverter fault information and the ratio of the current average power of the inverter on the alternating current side to the average power of the inverter on the direct current side. Therefore, the evaluation index S of the failure efficiency of the inverter is constructedinvIs composed of
Figure BDA0002631162750000102
In the formula (11), LjThe quantity of the inverter fault information represents whether the jth fault type of the inverter occurs or not, wherein the occurrence is 1 instead of 0;
Figure BDA0002631162750000103
represents the average power on the ac side of the inverter,
Figure BDA0002631162750000104
representing the average power of the direct current side of the inverter; 1,2, n; n represents the total number of inverter fault types.
In specific implementation, aiming at step 6, four faults mentioned in the embodiment are respectively manufactured in photovoltaic branch and inverter Simulink models, the maximum output power and the maximum output power of the photovoltaic branch under the fault condition, the average power and the average power of the inverter on the alternating current side under the fault condition and the average power of the direct current are collected, and the efficiency evaluation indexes are calculated by substituting equations (10) and (11). The method comprises the following specific steps:
(1) evaluation index calculation example for photovoltaic branch fault efficiency loss
According to the photovoltaic branch fault efficiency loss evaluation index definition formula (10), the evaluation index is calculated by the following steps:
1) obtaining irradiance S, branch average temperature T, actual branch output power and current fault information N under current environmental conditionsi. Assuming that a single component mismatch fault occurs in the branch at this time, the fault information amount N3＝1,N1＝N2＝N4＝0；
2) According to the current environmental condition, calculating the theoretical maximum power under the normal condition by using a photovoltaic branch mathematical model, and assigning to Pmpv(ii) a Assigning the actual branch output power to Ppv. This was simulated by Simulink to obtain Ppv＝5613W，Pmpv＝5633W；
3) Will N3＝1,N1＝N2＝N4＝0、Wzpv(1)～Wzpv(4)、Ppv、PmpvThe photovoltaic branch fault efficiency loss evaluation index S can be obtained by substituting the formula (10)pv. For this example, there are
Figure BDA0002631162750000111
The specific performance loss evaluation indices for the remaining faults are shown in table 4.
Table 4: data and efficiency loss evaluation index result of photovoltaic branch circuit in different faults
Figure BDA0002631162750000121
Drawing the calculation result into a graph, as shown in fig. 7, comparing two fault conditions of single-component shielding mismatch and single-component open circuit + single-component mismatch, although the actual maximum power of the branch is close to each other, the performance loss evaluation index has a large difference, because the two components in the latter have problems and the fault condition is more serious, the difference is reflected in the evaluation index; as can also be seen from fig. 7, the performance loss assessment index decreases with the severity of the fault due to the function of the composite evaluation cardinality under different fault types; the performance loss evaluation index under normal conditions is larger than the evaluation index under fault conditions, so that the performance loss evaluation index defined by equation (10) can measure the degree of performance loss under fault conditions and the severity of the fault.
(2) Evaluation index calculation example for inverter fault efficiency loss
According to the photovoltaic branch fault efficiency loss evaluation index definition formula (11), the evaluation index is calculated by the following steps:
1) obtaining the current AC measured average power, the DC side average power and the current fault information L of the inverterj. Assuming that a single switch tube open-circuit fault occurs in the branch circuit at this time, the fault information amount L4＝1,L1＝L2＝L3＝0；
2) Assigning the current AC output power to
Figure BDA0002631162750000122
DC side average power assignment to
Figure BDA0002631162750000123
Assuming that the load factor of the inverter is 100%, the situation is simulated by Simulink, and then
Figure BDA0002631162750000124
3) Mixing L with4＝1,L1＝L2＝L3＝0、Wzinv(1)～Wzinv(4)、
Figure BDA0002631162750000125
The photovoltaic branch fault efficiency loss evaluation index S can be obtained by substituting in formula (11)inv. For this example, there are
Figure BDA0002631162750000126
At a load rate of 100%, specific performance loss evaluation indexes at various failures are shown in table 5, and performance loss evaluation indexes at various failures at different loads are shown in table 6.
Table 5: data and performance loss evaluation index results at different failures at 100% load
Figure BDA0002631162750000131
Table 6: evaluation index S of inverter fault efficiency loss under different load conditionsinv
Figure BDA0002631162750000132
The results of table 6 are plotted in a graph, as shown in fig. 8. As can be seen from fig. 8, under the same load, there is a significant difference between the efficiency loss evaluation indexes of different fault types, and the efficiency loss evaluation index under the same fault type decreases with the decrease of the load rate, which also conforms to the rule of the inverter efficiency; the performance loss assessment index for normal conditions is significantly higher than the value at fault. Therefore, the inverter performance loss evaluation index defined by equation (11) can measure the performance loss degree and the severity of the fault in the case of the fault.

Claims (2)

1. A method for evaluating the efficiency loss of a photovoltaic branch and an inverter in a photovoltaic power station is characterized by comprising the following steps:
step 1, taking typical fault power losses of a photovoltaic branch and an inverter as evaluation indexes, and establishing a fault efficiency loss evaluation index system of the photovoltaic branch and the inverter;
step 2, obtaining the power loss ratio delta eta of the photovoltaic branch circuit caused by the ith fault type of the photovoltaic branch circuit by using the formula (1)pv(i)：
Figure FDA0002631162740000011
In the formula (1), Δ Ppv(i)Representing the increased power loss of the photovoltaic branch in the presence of the ith fault type; delta PstationRepresenting the loss of the photovoltaic power station in normal operation;
the power loss ratio delta eta of the inverter caused by the j fault type of the inverter is obtained by the formula (2)inv(j)：
Figure FDA0002631162740000012
In the formula (2), Δ Pinv(j)Indicating increased power loss of the inverter upon occurrence of the various jth fault types;
step 3, determining subjective evaluation weights W of various fault types of the photovoltaic branch and the inverter by using a 3-scale analytic hierarchy processpv(i)、Winv(j)(ii) a And the efficiency loss ratio delta eta is caused according to various fault types of the photovoltaic branch and the inverterpv(i)、Δηinv(j)Determining objective evaluation weight V of various fault types of photovoltaic branch and inverter by using complex correlation coefficient methodpv(i)、Vinv(j)；
Step 4, evaluating the main and objective efficiency loss evaluation weights W of the ith fault type of the photovoltaic branchpv(i)、Vpv(i)Linearly combining to obtain the comprehensive evaluation weight W of the ith fault efficiency loss of the photovoltaic branchzpv(i)；
Evaluating the main and objective performance loss evaluation weight W of the j fault type of the inverterinv(j)、Vinv(j)Linearly combining to obtain the j-th failure efficiency loss comprehensive evaluation weight W of the inverterzinv(j)；
Step 5, comprehensively evaluating the efficiency loss of each fault of the photovoltaic branchzpv(i)As a comprehensive evaluation base number, the photovoltaic branch fault efficiency evaluation index S is constructed by combining the photovoltaic branch fault information, the actual maximum power of the branch under the current environmental condition and the theoretical maximum power of the branch under the normal conditionpv；
Comprehensively evaluating the efficiency loss of each fault of the inverter by weight Wzinv(j)As a comprehensive evaluation base number, the inverter fault information, the average power of the direct current side of the inverter and the average power of the alternating current side of the inverter are combined to construct an inverter fault efficiency evaluation index Sinv；
And 6, obtaining an efficiency loss evaluation index S when the photovoltaic branch and the inverter are in failure according to the failure information of the photovoltaic branch and the inverter and the power data in the step 5pv、SinvThe value of (c).
2. The performance loss evaluating method according to claim 1, wherein the photovoltaic branch failure performance evaluation index S in step 5 is obtained by using equation (3)pv：
Figure FDA0002631162740000021
In the formula (3), NiRepresenting the photovoltaic branch fault information quantityThe number of components with the ith fault type in the branch circuit; ppvRepresenting the actual maximum output power of the photovoltaic branch; pmpvRepresenting the theoretical maximum output power of the photovoltaic branch under the current irradiance and temperature; 1,2,. m; m represents the total number of the photovoltaic branch fault types;
obtaining an inverter fault efficiency evaluation index S by using the formula (4)inv：
Figure FDA0002631162740000022
In the formula (4), LjThe quantity of the inverter fault information represents whether the jth fault type of the inverter occurs or not, wherein the occurrence is 1 instead of 0;
Figure FDA0002631162740000023
represents the average power on the ac side of the inverter,
Figure FDA0002631162740000024
representing the average power of the direct current side of the inverter; 1,2, n; n represents the total number of inverter fault types.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113203903A (en) * 2021-04-27 2021-08-03 合肥工业大学 Method for detecting and positioning cause of DC side fault of photovoltaic inverter
CN113642174A (en) * 2021-08-13 2021-11-12 合肥工业大学 Comprehensive evaluation method for efficiency loss of structural faults of three-level photovoltaic inverter

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5596586A (en) * 1994-07-14 1997-01-21 Mitsubishi Denki Kabushiki Kaisha Failure simulation method
CN104881003A (en) * 2015-03-18 2015-09-02 国家电网公司 Effectiveness evaluation method for metering production facilities
CN105514975A (en) * 2015-11-27 2016-04-20 国网冀北电力有限公司电力科学研究院 Energy efficiency prediction method of photovoltaic power generation system
KR20180036020A (en) * 2016-09-30 2018-04-09 헵시바주식회사 Fault diagnosis method of multi string solar cells connected to multi string solar inverter

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5596586A (en) * 1994-07-14 1997-01-21 Mitsubishi Denki Kabushiki Kaisha Failure simulation method
CN104881003A (en) * 2015-03-18 2015-09-02 国家电网公司 Effectiveness evaluation method for metering production facilities
CN105514975A (en) * 2015-11-27 2016-04-20 国网冀北电力有限公司电力科学研究院 Energy efficiency prediction method of photovoltaic power generation system
KR20180036020A (en) * 2016-09-30 2018-04-09 헵시바주식회사 Fault diagnosis method of multi string solar cells connected to multi string solar inverter

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113203903A (en) * 2021-04-27 2021-08-03 合肥工业大学 Method for detecting and positioning cause of DC side fault of photovoltaic inverter
CN113203903B (en) * 2021-04-27 2022-05-03 合肥工业大学 Method for detecting and positioning cause of DC side fault of photovoltaic inverter
CN113642174A (en) * 2021-08-13 2021-11-12 合肥工业大学 Comprehensive evaluation method for efficiency loss of structural faults of three-level photovoltaic inverter

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