CN113642174A - Comprehensive evaluation method for efficiency loss of structural faults of three-level photovoltaic inverter - Google Patents
Comprehensive evaluation method for efficiency loss of structural faults of three-level photovoltaic inverter Download PDFInfo
- Publication number
- CN113642174A CN113642174A CN202110930600.8A CN202110930600A CN113642174A CN 113642174 A CN113642174 A CN 113642174A CN 202110930600 A CN202110930600 A CN 202110930600A CN 113642174 A CN113642174 A CN 113642174A
- Authority
- CN
- China
- Prior art keywords
- fault
- photovoltaic inverter
- level photovoltaic
- transient
- evaluation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000011156 evaluation Methods 0.000 title claims abstract description 116
- 230000001052 transient effect Effects 0.000 claims abstract description 61
- 238000000034 method Methods 0.000 claims abstract description 44
- 238000005457 optimization Methods 0.000 claims abstract description 13
- 238000004088 simulation Methods 0.000 claims abstract description 5
- YBJHBAHKTGYVGT-ZKWXMUAHSA-N (+)-Biotin Chemical compound N1C(=O)N[C@@H]2[C@H](CCCCC(=O)O)SC[C@@H]21 YBJHBAHKTGYVGT-ZKWXMUAHSA-N 0.000 claims description 5
- FEPMHVLSLDOMQC-UHFFFAOYSA-N virginiamycin-S1 Natural products CC1OC(=O)C(C=2C=CC=CC=2)NC(=O)C2CC(=O)CCN2C(=O)C(CC=2C=CC=CC=2)N(C)C(=O)C2CCCN2C(=O)C(CC)NC(=O)C1NC(=O)C1=NC=CC=C1O FEPMHVLSLDOMQC-UHFFFAOYSA-N 0.000 claims description 5
- 239000004820 Pressure-sensitive adhesive Substances 0.000 claims 1
- 238000012423 maintenance Methods 0.000 abstract description 5
- 238000012544 monitoring process Methods 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 9
- 239000011159 matrix material Substances 0.000 description 7
- 238000012545 processing Methods 0.000 description 4
- 238000010248 power generation Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- NAWXUBYGYWOOIX-SFHVURJKSA-N (2s)-2-[[4-[2-(2,4-diaminoquinazolin-6-yl)ethyl]benzoyl]amino]-4-methylidenepentanedioic acid Chemical compound C1=CC2=NC(N)=NC(N)=C2C=C1CCC1=CC=C(C(=O)N[C@@H](CC(=C)C(O)=O)C(O)=O)C=C1 NAWXUBYGYWOOIX-SFHVURJKSA-N 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000010606 normalization Methods 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/16—Matrix or vector computation, e.g. matrix-matrix or matrix-vector multiplication, matrix factorization
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2113/00—Details relating to the application field
- G06F2113/04—Power grid distribution networks
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Mathematical Physics (AREA)
- Mathematical Analysis (AREA)
- Mathematical Optimization (AREA)
- Data Mining & Analysis (AREA)
- Computational Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- Pure & Applied Mathematics (AREA)
- Computing Systems (AREA)
- Computer Hardware Design (AREA)
- Evolutionary Computation (AREA)
- Algebra (AREA)
- Geometry (AREA)
- Databases & Information Systems (AREA)
- Software Systems (AREA)
- Photovoltaic Devices (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a comprehensive efficiency loss evaluation method for a structural fault of a three-level photovoltaic inverter, which comprises the following steps: based on a three-level photovoltaic inverter simulation model, transient power loss ratio delta eta of various structural faults is calculated respectively from the two aspects of transient state and steady stateTAnd steady state power loss ratio delta etaS(ii) a Evaluating the transient and steady state efficiency losses of various faults, respectively determining subjective and objective evaluation weights by using an optimal worst method and an entropy method, and solving the distribution coefficients of the transient, steady state subjective and objective weights by using a combined optimization model of the deviation square sum minimization between the subjective and objective weights and the maximization of the target layer comprehensive evaluation value; and calculating the comprehensive evaluation weight of each structural fault, thereby constructing a comprehensive efficiency loss evaluation factor of the structural fault of the inverter.The method can measure the efficiency loss degree and the fault severity degree during various structural faults, thereby providing reference for intelligent operation, maintenance and monitoring of the three-level photovoltaic inverter.
Description
Technical Field
The invention relates to a comprehensive efficiency loss evaluation method for a structural fault of a three-level photovoltaic inverter, and belongs to the technical field related to operation, maintenance and monitoring of photovoltaic power stations.
Background
The photovoltaic inverter is a pivotal device of the photovoltaic power generation system, and conversion from direct current to alternating current is achieved through a control switch device. The operating conditions of the photovoltaic inverter have a significant impact on the reliable operation of the entire photovoltaic power generation system. However, the natural environment of the photovoltaic power plant is generally harsh, and the internal devices can bear high electrical stress and high thermal stress for a long time. Meanwhile, the influence of disturbance on the power grid and the direct current side can also improve the fault occurrence rate of the photovoltaic inverter, so that efficiency loss is caused. Therefore, it is necessary to evaluate the performance loss of various structural faults of the photovoltaic inverter and quantitatively analyze the severity of the faults and the performance loss.
At present, the three-level photovoltaic inverter is widely applied. Compared with a traditional two-level inverter, the three-level photovoltaic inverter has the advantages that the number of power switching devices needed is larger, the circuit topology structure is more complex, the probability of faults is higher, the fault form is more diversified, and the rapidity and the accuracy of fault diagnosis analysis and efficiency evaluation are directly influenced.
On the other hand, factors affecting the accuracy of the efficacy assessment also include the rationality of the assessment method. Most of the existing evaluation methods take the whole normally-operated photovoltaic power station as an evaluation object. For example, the system energy efficiency PR value is taken as a globally recognized key efficiency index, and the method has guiding significance for measuring the power generation performance of the whole photovoltaic system under the normal operation condition. However, the efficiency of the photovoltaic power station is evaluated by the system energy efficiency PR value, generally, a month or a year is taken as a time unit, and factors such as a geographical position, meteorological conditions, illumination intensity and the like which affect the efficiency of the photovoltaic power station are selected as evaluation indexes, so that the efficiency evaluation is more favored for the normal operation of the photovoltaic system, and the method is not suitable for the efficiency loss evaluation of devices in the photovoltaic system caused by faults. In the only existing failure efficiency loss evaluation methods, an analytic hierarchy process becomes a preferred strategy for evaluation, but when evaluation indexes are too many, data statistics is large, and a calculation process is too complicated, so that evaluation weight is difficult to determine.
Therefore, the existing method for evaluating the efficiency of the photovoltaic inverter has certain disadvantages, and especially, the efficiency loss evaluation research of the three-level photovoltaic inverter in the case of a fault involves less. Therefore, establishing an efficiency loss evaluation method for the photovoltaic grid-connected inverter under various structural faults effectively measures the severity of the faults of the photovoltaic inverter and quantifies the efficiency loss degree, and becomes a big problem to be solved urgently.
Disclosure of Invention
The invention provides a comprehensive efficiency loss evaluation method for a three-level photovoltaic inverter structural fault, aiming at overcoming the defects of the prior art in the aspect of research on efficiency loss evaluation of the three-level photovoltaic inverter under the fault condition, so that the severity of the photovoltaic inverter fault can be effectively measured and the efficiency loss degree can be quantized, the transient and steady conditions of the fault can be considered, the evaluation flow can be improved, the data processing amount can be reduced, and the rapidity and the accuracy of the efficiency loss evaluation can be improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention discloses a comprehensive evaluation method for efficiency loss of a structural fault of a three-level photovoltaic inverter, which is characterized by comprising the following steps of:
step 1, acquiring the type of structural faults of a three-level photovoltaic inverter in a photovoltaic power station system, and counting the types of the structural faults of the three-level photovoltaic inverter, including open-circuit faults and short-circuit faults of epsilon components;
transient power loss value delta P caused by structural fault of three-level photovoltaic inverterTAnd steady state power loss value Δ PSThe method is used as an evaluation index, and is based on the established three-level photovoltaic inverter structural fault simulation model and used for simulating various faults and acquiring a specific numerical value of the evaluation index;
step 2, obtaining the transient power loss ratio delta eta of the j-th structural fault of the three-level photovoltaic inverter by using the formula (1) and the formula (2) respectivelyT(j)And steady state power loss ratio delta etaS(j)：
In the formulae (1) and (2), PdcRepresents the input power at the direct current side, delta P, of the photovoltaic power station system in the normal operation stateT(j)Represents the value of transient power loss, delta P, caused by the j-th structural faultS(j)Representing a steady-state power loss value caused by the j-th type structural fault; j ═ 1,2, …, n, n indicates the number of categories of structural failure;
step 3, respectively determining transient subjective evaluation weights W of jth structural faults of the three-level photovoltaic inverter by using an optimal worst method1T(j)And steady state subjective evaluation weight W1S(j)；
Step 4, according to the transient power loss proportion delta eta caused by the jth structural fault of the three-level photovoltaic inverterT(j)And steady state power loss ratio delta etaS(j)Respectively determining the transient objective evaluation weight W of the jth fault of the three-level photovoltaic inverter by using an entropy method2T(j)And steady state objective assessment weight W2S(j)；
Step 5, respectively carrying out transient state main evaluation weight W and objective evaluation weight W by utilizing a method for minimizing the sum of squared deviations between the main evaluation weight and the objective evaluation weight and a method for maximizing the target layer comprehensive evaluation value1T(j)、W2T(j)And steady state subjective and objective assessment weight W1S(j)、W2S(j)Performing weighted combination to correspondingly obtain a transient combined optimization model and a steady combined optimization model;
respectively solving the transient state combination optimization model and the steady state combination optimization model to correspondingly obtain transient state main and objective weight distribution coefficients alphaT、βTAnd a steady-state objective and subjective weight distribution coefficient alphaS、βSThe value of (d);
respectively calculating transient comprehensive evaluation weight W of jth structural fault of the three-level photovoltaic inverter by using formula (3) and formula (4)3T(j)And steady state comprehensive evaluation weight W3S(j)，j＝1,2,…,n：
W3T(j)＝αTW1T(j)+βTW2T(j) (3)
W3S(j)＝αSW1S(j)+βSW2S(j) (4)
Step 6, comprehensively evaluating the transient state and the steady state of the jth structural fault of the three-level photovoltaic inverter by using the weight W3T(j)、W3S(j)Performing linear combination to obtain the comprehensive evaluation weight W of the performance loss of the jth structural fault of the three-level photovoltaic inverterinv(j)；
Comprehensively evaluating the performance loss by weight Winv(j)The comprehensive evaluation factor S of the fault efficiency loss of the three-level photovoltaic inverter is constructed by taking the comprehensive evaluation base number of the efficiency loss and combining the fault information of the three-level photovoltaic inverter, the average power of the direct current side and the average power of the alternating current side of the three-level photovoltaic inverterinv。
The comprehensive efficiency loss evaluation method is also characterized in that a fault efficiency loss comprehensive evaluation factor S of the three-level photovoltaic inverter is constructed by using the formula (5)inv：
In the formula (5), F(j)Indicating whether the jth structural fault type occurs or not, if F(j)When F is 1, it is indicated to occur(j)When 0, it does not occur;
represents the average power output by the ac side of the three-level photovoltaic inverter,
representing the average power input at the dc side of the three-level photovoltaic inverter.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention takes the power loss ratio caused by common structural fault types of the three-level photovoltaic inverter as a measurement basis, considers from two aspects of fault transient state and stable state, takes the transient state and stable state power loss values as evaluation indexes, establishes a three-level photovoltaic inverter efficiency loss evaluation system, and provides a method for quantitatively evaluating the severity and efficiency loss degree of the three-level photovoltaic inverter when structural faults occur, which is beneficial for operation and maintenance personnel to effectively know whether the inverter fails and the severity of the faults, so that reasonable fault treatment measures are taken, and the method has important significance for intelligent operation and maintenance and monitoring of a photovoltaic power station.
2. According to expert experience judgment and actual operation data, a combined weighting method based on the combination of an optimal worst method (BWM) and an entropy method (EWM) is introduced, the optimal combination between two optimized target planning models of the quadratic sum minimization of deviation between the optimal worst method and the EWM and the maximization of a target layer comprehensive evaluation value is selected, the distribution coefficient of subjective and objective weights is solved, the combined weight of various structural faults of the three-level photovoltaic inverter is further determined, and the severity of the faults can be effectively reflected, namely the larger the weight is, the more the faults are serious. Meanwhile, the BWM-EWM combined evaluation method effectively improves the complicated process of the analytic hierarchy process in calculating the weight, gives consideration to the influence of subjective and objective factors, and reasonably distributes weighting coefficients, so that the evaluation result is more scientific and accurate.
3. The method takes the combined weight of the faults as a comprehensive evaluation base number, and simultaneously combines the fault information and the power data of the three-level photovoltaic inverter to construct a comprehensive evaluation factor of the fault efficiency loss; the efficiency loss degree caused by the current fault is reflected by the power data, the severity degree of the current fault is reflected by the fault information and the fault combination weight, the defect that the severity degree of the fault cannot be reflected by only paying attention to the normal operation efficiency of the three-level photovoltaic inverter in the conventional evaluation method is overcome, and the purposes of effectively evaluating the fault efficiency loss and the fault severity degree of the three-level photovoltaic inverter are achieved.
4. According to the invention, for the actually-operated three-level photovoltaic inverter, before the equipment parameters and the structure are not changed, the determined comprehensive evaluation cardinality of various structural fault types can be kept unchanged for a long time, and then the comprehensive evaluation factor of the fault efficiency loss of the inverter can be directly calculated only by acquiring the fault information and the related power data of the three-level photovoltaic inverter, so that the actual use is simple, convenient and rapid, and the data processing amount is small.
Drawings
FIG. 1 is a flow chart of the method for comprehensive evaluation of performance loss according to the present invention;
FIG. 2 is a topological diagram of a midpoint clamping type three-level photovoltaic inverter in the prior art;
FIG. 3 is a single-phase open-circuit fault topology diagram of a filter inductor of an inverter in the prior art;
FIG. 4 is a single-phase short-circuit fault topology diagram of a filter inductor of an inverter in the prior art;
FIG. 5 is a prior art single tube open fault topology diagram for a freewheeling diode of an inverter;
FIG. 6 is a prior art inverter clamp diode single tube open circuit fault topology;
FIG. 7a is a topology diagram of a single-tube open-circuit fault of an inverter IGBT in the prior art;
FIG. 7b is a topology diagram of an open-circuit fault of two tubes of a half-bridge arm on the same phase and the same side of an inverter IGBT in the prior art;
FIG. 7c is a topology diagram of a two-tube open circuit fault of an inverter IGBT in-phase and opposite-side half-bridge arm in the prior art;
FIG. 7d is a topology diagram of an open circuit fault of two tubes of a half bridge arm on the same side of an inverter IGBT out-phase in the prior art;
FIG. 7e is a topology diagram of a two-tube open circuit fault of an inverter IGBT out-of-phase opposite side half bridge arm in the prior art;
fig. 8 is a comparison graph of the comprehensive evaluation factor curves of the performance loss under different loads and faults according to the present invention.
Detailed Description
In this embodiment, a comprehensive evaluation method for performance loss of a structural fault of a three-level photovoltaic inverter is a process of transient transition to a steady state of the structural fault caused by components such as a diode, a power switching tube, and a filter inductor in a main circuit of the inverter, as shown in fig. 1, and includes the following specific steps:
step 1, combing, summarizing and summarizing the types and characteristics of the structural faults of the existing three-level photovoltaic inverter, and counting the types of the structural faults of the inverter, including open-circuit faults and short-circuit faults of epsilon components; in this embodiment, open-circuit and short-circuit faults of 5 types of components, mainly including a dc side capacitor, a filter inductor, a freewheeling diode, a clamping diode and a power switch tube, are counted. The failure performance characteristics are shown in table 1.
Table 1: various structural fault performance characteristics of three-level photovoltaic inverter
The method mainly aims at 5 major structural faults of three-level photovoltaic inverter filter inductor open circuit, filter inductor short circuit, freewheeling diode open circuit, clamp diode open circuit and IGBT open circuit to carry out efficiency loss evaluation. In the embodiment, a widely-used midpoint clamping type three-level photovoltaic inverter is taken as an example, as shown in fig. 2.
The structural faults of two phases or more than two phases of the filter inductor, the freewheeling diode and the clamping diode can cause system breakdown and shutdown, and the five types of structural faults can be subdivided into the following categories:
(1) the single-phase open circuit fault of the filter inductor has a topology shown in FIG. 3;
(2) the single-phase short circuit fault of the filter inductor is shown in the topology of figure 4;
(3) the single tube open circuit fault of the freewheeling diode has the topology shown in FIG. 5;
(4) the clamping diode single tube open circuit fault, the topology is shown in fig. 6;
(5) an IGBT single tube open circuit fault, wherein the topology is shown in FIG. 7 a;
(6) the open-circuit fault of two tubes of the half-bridge arm on the same phase and the same side of the IGBT is shown in a topology shown in figure 7 b;
(7) the open-circuit fault of the two tubes of the half-bridge arms on the same phase and different sides of the IGBT is shown in a topology of FIG. 7 c;
(8) the half-bridge arm two tubes at the same side of the IGBT out-phase have open circuit faults, and the topology is shown in FIG. 7 d;
(9) the half-bridge arm two-tube open circuit fault of the IGBT out-of-phase opposite side has 9 fault types as shown in the topology of fig. 7 e.
Therefore, the transient power loss value Δ P caused by the above 9 fault typesTAnd steady state power loss value Δ PSThe method is used as an evaluation index of the failure efficiency loss of the three-level photovoltaic inverter. Based on the established three-level photovoltaic inverter structural fault simulation model, simulating various faults and acquiring specific numerical values of evaluation indexes, wherein the specific numerical values are respectively expressed by delta PT(j)And Δ PS(j)Instead, the inverter fault index at this time is j 1,2, …,9, i.e., n 9.
Step 2, obtaining the transient power loss ratio delta eta of the j-th structural fault of the three-level photovoltaic inverter by using the formula (1) and the formula (2) respectivelyT(j)And steady state power loss ratio delta etaS(j)：
In the formulae (1) and (2), PdcRepresents the input power at the direct current side, delta P, of the photovoltaic power station system in the normal operation stateT(j)Represents the value of transient power loss, delta P, caused by the j-th structural faultS(j)Indicating the steady state power loss value caused by the j-th type structural fault. Specifically, the results are shown in tables 2 and 3.
Table 2: transient power loss ratio of structural fault of three-level photovoltaic inverter
Table 3: steady-state power loss ratio of three-level photovoltaic inverter structural fault
Step 3, respectively determining transient subjective evaluation weights W of jth structural faults of the three-level photovoltaic inverter by using an optimal worst method (BWM)1T(j)And steady state subjective evaluation weight W1S(j). The method comprises the following specific steps:
step 3.1, in the fault type set F ═ F1,f2,…,fnRespectively selecting optimal and worst fault types F according to expert experienceB、FW；
Step 3.2, scoring by adopting 1-9 marks, and determining the optimal fault type FBConstructing an optimal comparison vector A in comparison to the severity of performance loss for other fault typesB＝(aB1,aB2,…,aBn)；
Step 3.3, determining other fault types to be compared with the worst fault type FWIs not serious, the worst comparison vector A is constructedW＝(a1W,a2W,…,anW)T；
Step 3.4, calculating the optimal solution W of the subjective evaluation weight by the formula (3)1＝(w1 *,w2 *,…,wn *)。
1) According to the steps 3.1-3.4, transient subjective evaluation weights W of 9 structural fault types are determined1T
Single-phase open-circuit fault f of filter inductor under condition of transient efficiency loss1Single tube open fault f of freewheeling diode for optimum fault type3The worst failure type. The remaining fault types are compared with f1Comparing to obtain ATB＝(a12,a13,a14,a15,a16,a17,a18,a19) (7,8,7,4,4,2,2, 3). The remaining fault types are compared with f3Comparing to obtain ATW＝(a13,a23,a43,a53,a63,a73,a83,a93)T＝(7,2,1,3,3,6,6,4)T. Calculating the scoring data according to the formula (3) to obtain the transient subjective evaluation weight W1TThe final result of (1). As shown in table 4.
TABLE 4 subjective evaluation of transient for structural fault types for three-level photovoltaic inverters
| Class of failure | f1 | f2 | f3 | f4 | f5 | f6 | f7 | f8 | f9 |
| Weight coefficient | 0.261 | 0.052 | 0.035 | 0.037 | 0.084 | 0.083 | 0.168 | 0.168 | 0.112 |
2) According to the step 3.1 to the step 3.4, determining the steady-state subjective evaluation weight W of the 9 structural fault types1S；
Under the steady state condition, the IGBT same-phase and opposite-side half-bridge arm two-tube open-circuit fault f7Single-tube short-circuit fault f of freewheeling diode for optimal fault type2The worst failure type. The remaining fault types are compared with f7Comparing to obtain ASB＝(a71,a72,a73,a74,a75,a76,a78,a79) (1,6,7,5,5,4,3, 4). The remaining fault types are compared with f2Comparing to obtain ASW＝(a12,a32,a42,a52,a62,a72,a82,a92)T＝(6,2,4,3,4,7,5,4)T. Calculating the scoring data according to the formula (3) to obtain the steady state subjective evaluation weight W1SThe final result of (1). As shown in table 5.
TABLE 5 Steady-state subjective evaluation weights for three-level photovoltaic inverter structural fault types
| Class of failure | f1 | f2 | f3 | f4 | f5 | f6 | f7 | f8 | f9 |
| Weight coefficient | 0.228 | 0.038 | 0.047 | 0.082 | 0.069 | 0.090 | 0.241 | 0.115 | 0.090 |
Step 4, according to the transient power loss proportion delta eta caused by the jth structural fault of the three-level photovoltaic inverter obtained in the step 2T(j)And steady state power loss ratio delta etaS(j)Respectively determining transient objective evaluation weight W of j-th fault of the three-level photovoltaic inverter by using entropy method (EWM)2T(j)And steady state objective assessment weight W2S(j). The method comprises the following specific steps:
step 4.1, according to the specific numerical value of the power loss ratio in the step 2, m load rate conditions exist, and a decision matrix of the original data can be obtained according to n types of fault types to be evaluated: a ═ aij)m*n. Wherein, aijAnd the performance loss ratio of the j-th type structural fault under the condition of the i-th load rate is shown. Using formula (4) to pair a ═ aij)m*nCarrying out standardization processing to obtain a standardized matrix B ═ Bij)m*n；
Step 4.2, carrying out normalization processing on the standardized matrix by a formula (5);
4.3, solving the entropy value of the fault type to be evaluated by a formula (6);
in the formula (I), the compound is shown in the specification,
step 4.4, calculating objective evaluation weight W of j-th fault of the three-level photovoltaic inverter by using a formula (7)2(j)。
1) According to the step 4.1 to the step 4.4, determining transient objective evaluation weights W of 9 structural fault types2T
From the ratio of transient power loss Δ ηT(j)Decision matrix obtained from raw data:
according to the formulas (4) to (7), the decision matrix A is matchedTCalculating to obtain the transient objective evaluation weight W2TAnd (5) obtaining a final result. As shown in table 6.
TABLE 6 objective assessment weight of transient state of three-level photovoltaic inverter structural fault types
| Class of failure | f1 | f2 | f3 | f4 | f5 | f6 | f7 | f8 | f9 |
| Weight coefficient | 0.146 | 0.078 | 0.074 | 0.075 | 0.109 | 0.112 | 0.142 | 0.145 | 0.119 |
2) Determining the steady-state objective evaluation weight W of the 9 structural fault types according to the step 4.1 to the step 4.42S；
From steady state power loss ratio Δ ηS(j)Decision matrix obtained from raw data:
according to the formulas (4) to (7), the decision matrix A is matchedSCalculating to obtain the steady-state objective evaluation weight W2SAnd (5) obtaining a final result. As shown in table 7.
TABLE 7 Steady-State objective evaluation weights for three-level photovoltaic inverter structural fault types
| Class of failure | f1 | f2 | f3 | f4 | f5 | f6 | f7 | f8 | f9 |
| Weight coefficient | 0.170 | 0.086 | 0.087 | 0.094 | 0.090 | 0.095 | 0.173 | 0.113 | 0.092 |
Step 5, respectively calculating transient state and steady state comprehensive evaluation weights W of the j-th structural fault of the three-level photovoltaic inverter by using a combined optimization model with minimized deviation square sum between the subjective evaluation weight and the objective evaluation weight and maximized target layer comprehensive evaluation value3T(j)、W3S(j)。
And 5.1, constructing a deviation square sum minimization model between subjective weight and objective weight according to a formula (8):
α+β＝1,(α≥0,β≥0)
step 5.2, constructing a target layer comprehensive evaluation value maximization model according to a formula (9):
in the formula (9), bijThe power loss ratio a of the jth fault type to be evaluated under the ith load rate condition isijNormalized values.
Step 5.3, the two optimization models in the step 5.1 and the step 5.2 are combined to construct a combined optimization model, as shown in a formula (10):
step 5.4, the solving process of the optimization model essentially solves the problem of extreme values under constraint conditions, and the distribution coefficients of the main weight and the objective weight are respectively solved by establishing a Lagrange function and utilizing a Lagrange multiplier method:
in the formula (11), λ is a Lagrange operator.
Order to
Obtaining by solution:
order to
Obtaining by solution:
order to
Obtaining by solution:
α+β-1＝0 (14)
by combining the above equations (12), (13) and (14), the values of α and β can be obtained:
step 5.5, the subjective and objective weight data under the transient and steady state conditions obtained in the step 3 and the step 4 are respectively substituted into formulas (15) and (16) for calculation, and the main and objective weight distribution coefficients alpha of the transient and steady state performance loss are respectively obtainedT、βTAnd alphaS、βS. Specific numerical values are shown in table 8.
TABLE 8 subjective and objective weight distribution coefficients for transient and steady state performance loss
Step 5.6, calculating transient state and steady state comprehensive evaluation weights W of j-th structural faults of the three-level photovoltaic inverter by using a formula (17) and a formula (18) respectively3T(j)、W3S(j). Specific numerical values are shown in table 9.
W3T(j)＝αTW1T(j)+βTW2T(j)(j＝1,2,…,n) (17)
W3S(j)＝αSW1S(j)+βSW2S(j)(j＝1,2,…,n) (18)
TABLE 9 comprehensive evaluation weights for transient and steady states of structural fault types of three-level photovoltaic inverter
And 6, when the three-level photovoltaic inverter has structural faults, a transient process from a transient state to a steady state exists, and in order to take the influences of transient impact and steady-state continuous loss on fault efficiency loss evaluation into consideration, the transient state and steady-state comprehensive evaluation weight W is used for evaluating the transient state and steady-state continuous loss3T(j)、W3S(j)Performing linear combination, as shown in formula (19), to obtain a comprehensive evaluation weight W for the performance loss of the j-th structural fault of the inverterinv(j)。
Winv(j)＝μW3T(j)+νW3S(j)(j＝1,2,…,n) (19)
In the formula (19), μ ═ ν ═ 0.5, that is, the portions of the transient and steady state performance loss comprehensive assessment weights, each of which accounts for half, are taken into consideration for both transient and steady state conditions. The specific values obtained are shown in table 10.
TABLE 10 comprehensive evaluation weight for structural failure efficiency loss of three-level photovoltaic inverter
W is to beinv(j)As an efficiency loss comprehensive evaluation base number, the inverter fault information, the average power of the DC side of the inverter and the average power of the AC side of the inverter are combined to construct an inverter fault efficiency loss comprehensive evaluation factor SinvThe expression is shown as formula (20):
in the formula (20), F(j)And reflecting the fault information of the three-level photovoltaic inverter, specifically indicating whether the jth fault type occurs, wherein the occurrence is 1, and the non-occurrence is 0.
Represents the average power output by the ac side of the inverter,
indicating the average power input at the dc side of the inverter.
In specific implementation, for step 6, 9 types of structural faults mentioned in the embodiment are respectively manufactured in a three-level photovoltaic inverter simulation model, the average power of the alternating current side and the average power of the direct current side of the inverter under the fault condition are collected, and the comprehensive evaluation factor of the efficiency loss of the inverter is calculated by substituting an equation (20). The method comprises the following specific steps:
(1) and acquiring the current average power of the AC side, the current average power of the DC side and the current fault information of the inverter. Assuming that the current three-level photovoltaic inverter has a single-phase open-circuit fault of a filter inductor, the fault information amount is
(2) Assigning the current AC output power to
DC side average power assignment to
Assuming that the load factor of the inverter is 100%, the method can obtain
(3) The information is substituted into the formula (20), and the efficiency loss evaluation factor S of the three-level photovoltaic inverter at the moment can be obtainedinv. For this example, there are
Similarly, efficiency loss evaluation factors of the three-level photovoltaic inverter under different fault types and different load conditions can be obtained, which is specifically shown in table 11.
TABLE 11 comprehensive evaluation factor for three-level photovoltaic inverter fault efficiency loss under different load conditions
The results of Table 11 are plotted as a comparison of the curves, as shown in FIG. 8. Under the condition of the same load rate, the comprehensive efficiency loss evaluation factor of the three-level photovoltaic inverter has a more obvious gap for different fault types. The evaluation index of the performance loss of the single-tube open-circuit fault of the freewheeling diode is the highest, which means that the severity of the fault is the smallest, and the evaluation index is also matched with the actual situation. In addition, for the same fault category, under the condition of different load rates, the comprehensive evaluation factor of the photovoltaic inverter fault efficiency loss is positively correlated with the load rate and is increased along with the increase of the load rate, so that the rule of the inverter operation efficiency is met. Therefore, the severity and the efficiency loss degree of various structural faults of the inverter are quantitatively reflected through the comprehensive evaluation factor of the fault efficiency loss of the three-level photovoltaic inverter, and the method is feasible and effective.
In summary, the method of the invention considers from two aspects of fault transient state and steady state, accurately and effectively determines subjective and objective weights of the photovoltaic grid-connected inverter under various faults by using an optimal worst method (BWM) and an entropy method (EWM), reasonably determines distribution coefficients of the subjective and objective weights by using a combined optimization model of dispersion sum of squares minimization and maximization of a target layer comprehensive evaluation value, calculates comprehensive evaluation factors of the efficiency loss of the photovoltaic grid-connected inverter under the fault condition, further effectively quantificationally reflects the severity and the efficiency loss degree of the inverter when various structural faults occur, and provides a reference thought for intelligent operation, maintenance and monitoring of the photovoltaic power station.
Claims (2)
1. A comprehensive evaluation method for efficiency loss of a structural fault of a three-level photovoltaic inverter is characterized by comprising the following steps:
step 1, acquiring the type of structural faults of a three-level photovoltaic inverter in a photovoltaic power station system, and counting the types of the structural faults of the three-level photovoltaic inverter, including open-circuit faults and short-circuit faults of epsilon components;
transient power loss value delta P caused by structural fault of three-level photovoltaic inverterTAnd steady state power loss value Δ PSAs an evaluation index, based on the established three-level photovoltaic inverter junctionThe structural fault simulation model is used for simulating various faults and acquiring specific numerical values of evaluation indexes;
step 2, obtaining the transient power loss ratio delta eta of the j-th structural fault of the three-level photovoltaic inverter by using the formula (1) and the formula (2) respectivelyT(j)And steady state power loss ratio delta etaS(j)：
In the formulae (1) and (2), PdcRepresents the input power at the direct current side, delta P, of the photovoltaic power station system in the normal operation stateT(j)Represents the value of transient power loss, delta P, caused by the j-th structural faultS(j)Representing a steady-state power loss value caused by the j-th type structural fault; j ═ 1,2, …, n, n indicates the number of categories of structural failure;
step 3, respectively determining transient subjective evaluation weights W of jth structural faults of the three-level photovoltaic inverter by using an optimal worst method1T(j)And steady state subjective evaluation weight W1S(j)；
Step 4, according to the transient power loss proportion delta eta caused by the jth structural fault of the three-level photovoltaic inverterT(j)And steady state power loss ratio delta etaS(j)Respectively determining the transient objective evaluation weight W of the jth fault of the three-level photovoltaic inverter by using an entropy method2T(j)And steady state objective assessment weight W2S(j)；
Step 5, respectively carrying out transient state main evaluation weight W and objective evaluation weight W by utilizing a method for minimizing the sum of squared deviations between the main evaluation weight and the objective evaluation weight and a method for maximizing the target layer comprehensive evaluation value1T(j)、W2T(j)And steady state subjective and objective assessment weight W1S(j)、W2S(j)Performing weighted combination to correspondingly obtain a transient combination optimization model and a steady combination optimizationModeling;
respectively solving the transient state combination optimization model and the steady state combination optimization model to correspondingly obtain transient state main and objective weight distribution coefficients alphaT、βTAnd a steady-state objective and subjective weight distribution coefficient alphaS、βSThe value of (d);
respectively calculating transient comprehensive evaluation weight W of jth structural fault of the three-level photovoltaic inverter by using formula (3) and formula (4)3T(j)And steady state comprehensive evaluation weight W3S(j)，j＝1,2,…,n：
W3T(j)＝αTW1T(j)+βTW2T(j) (3)
W3S(j)＝αSW1S(j)+βSW2S(j) (4)
Step 6, comprehensively evaluating the transient state and the steady state of the jth structural fault of the three-level photovoltaic inverter by using the weight W3T(j)、W3S(j)Performing linear combination to obtain the comprehensive evaluation weight W of the performance loss of the jth structural fault of the three-level photovoltaic inverterinv(j)；
Comprehensively evaluating the performance loss by weight Winv(j)The comprehensive evaluation factor S of the fault efficiency loss of the three-level photovoltaic inverter is constructed by taking the comprehensive evaluation base number of the efficiency loss and combining the fault information of the three-level photovoltaic inverter, the average power of the direct current side and the average power of the alternating current side of the three-level photovoltaic inverterinv。
2. The performance loss comprehensive evaluation method according to claim 1, wherein the failure performance loss comprehensive evaluation factor S of the three-level photovoltaic inverter is constructed by using equation (5)inv：
In the formula (5), F(j)Indicating whether the jth structural fault type occurs or not, if F(j)When 1, it indicates hairUnprocessed, if F(j)When 0, it does not occur;
represents the average power output by the ac side of the three-level photovoltaic inverter,
representing the average power input at the dc side of the three-level photovoltaic inverter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110930600.8A CN113642174A (en) | 2021-08-13 | 2021-08-13 | Comprehensive evaluation method for efficiency loss of structural faults of three-level photovoltaic inverter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110930600.8A CN113642174A (en) | 2021-08-13 | 2021-08-13 | Comprehensive evaluation method for efficiency loss of structural faults of three-level photovoltaic inverter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113642174A true CN113642174A (en) | 2021-11-12 |
Family
ID=78421718
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110930600.8A Pending CN113642174A (en) | 2021-08-13 | 2021-08-13 | Comprehensive evaluation method for efficiency loss of structural faults of three-level photovoltaic inverter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113642174A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA3006506A1 (en) * | 2015-11-13 | 2017-05-18 | Marquette University | An on-line diagnostic method for switch faults in power converters |
| CN111934618A (en) * | 2020-08-13 | 2020-11-13 | 合肥工业大学 | Photovoltaic branch and inverter efficiency loss evaluation method in photovoltaic power station |
| CN112766739A (en) * | 2021-01-22 | 2021-05-07 | 北京工商大学 | BWM-E model-based evaluation method for heavy metal pollution in meat products |
| CN112966914A (en) * | 2021-02-26 | 2021-06-15 | 国家电网有限公司 | Intelligent quality control method for assembled transformer substation based on GIM-5D |
-
2021
- 2021-08-13 CN CN202110930600.8A patent/CN113642174A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA3006506A1 (en) * | 2015-11-13 | 2017-05-18 | Marquette University | An on-line diagnostic method for switch faults in power converters |
| CN111934618A (en) * | 2020-08-13 | 2020-11-13 | 合肥工业大学 | Photovoltaic branch and inverter efficiency loss evaluation method in photovoltaic power station |
| CN112766739A (en) * | 2021-01-22 | 2021-05-07 | 北京工商大学 | BWM-E model-based evaluation method for heavy metal pollution in meat products |
| CN112966914A (en) * | 2021-02-26 | 2021-06-15 | 国家电网有限公司 | Intelligent quality control method for assembled transformer substation based on GIM-5D |
Non-Patent Citations (1)
| Title |
|---|
| 艾龙海: "基于组合赋权法的高校图书馆纸质图书质量评估研究", 中国优秀硕士学位论文全文数据库, no. 2021, pages 35 - 38 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104124918B (en) | Comprehensive detection method for generating efficiency of photovoltaic power station | |
| CN104408562B (en) | A kind of photovoltaic system generating efficiency comprehensive estimation method based on BP neural network | |
| CN111010083B (en) | Early warning system is synthesized to photovoltaic power plant trouble | |
| CN104319785B (en) | Source flow path electrical subdivision-based wind power system key node identification method | |
| CN107358335A (en) | A kind of distributed photovoltaic efficiency evaluation method and system based on internet | |
| CN105894212A (en) | Comprehensive evaluation method for coupling and decoupling ring of electromagnetic ring network | |
| CN110705887A (en) | Low-voltage transformer area operation state comprehensive evaluation method based on neural network model | |
| CN109345090A (en) | A kind of rack evaluation method promoted based on distribution network reliability | |
| CN109508909B (en) | Evaluation method and system for health degree of photovoltaic inverter | |
| CN111934618B (en) | Photovoltaic branch and inverter efficiency loss evaluation method in photovoltaic power station | |
| CN111091223A (en) | Distribution transformer short-term load prediction method based on Internet of things intelligent sensing technology | |
| CN113642174A (en) | Comprehensive evaluation method for efficiency loss of structural faults of three-level photovoltaic inverter | |
| CN115564310A (en) | Reliability evaluation method for new energy power system based on convolutional neural network | |
| CN112653185B (en) | Efficiency evaluation method and system of distributed renewable energy power generation system | |
| CN112016838B (en) | Contribution rate calculation method, system and terminal equipment of power distribution network energy efficiency index system | |
| CN114421465A (en) | Power grid parameter identification and verification method and device based on element topology and storage medium | |
| CN114580938A (en) | Comprehensive power distribution effect evaluation method with multiple data dimensions | |
| CN106886851A (en) | Electric energy meter standby redundancy Forecasting Methodology based on electric energy meter repair based on condition of component | |
| CN108717597B (en) | Grid engineering operation benefit evaluation method and system for optimizing grid structure | |
| Zhang et al. | Power Quality Evaluation Based on the Fusion of Improved Entropy and Analytic Hierarchy Process | |
| CN110533256A (en) | Method for predicting heat supply load on demand side | |
| CN112288285B (en) | Photovoltaic power station string attenuation rate evaluation method based on generalized extreme value distribution | |
| Ji et al. | A novel combinational evaluation method of voltage and reactive power in regional power grid containing renewable energy | |
| CN116307831A (en) | Method, system, equipment and storage medium for evaluating grid network frame optimization implementation effect | |
| Zhao et al. | Evaluation of distribution network carrying capacity considering multi distributed resource access |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |