Reliability Assessment of Photovoltaic Generation Systems
Ahmed Mohamed Abdel Rahman Mustafa;
Abstract
Photovoltaic (PV) systems are currently getting more attention due to the declining prices of PV modules. This price declination makes grid connected PV systems one of the strong participants in the electricity generation mix of several countries around the globe.
Grid connected PV systems have several topologies with regards to their interface with the electric network. These include centralized, string, multi-string, master-slave and micro-converter topologies. These topologies differ from each other from the view point of cost and control.
The aim of this thesisis to perform a comparative study on the reliability of different topologies of grid connected photovoltaic (PV) systems. The reliability of each topology is investigated by considering the components of the system and their connection. Moreover, the impact of different environmental conditions, including irradiance and temperature, is considered in the analysis.
To perform the required analysis, suitable reliability indices that are based on calculating the probability of the different operating states are used.These states are evaluated using two different methods: first, the state enumeration method (SE) which is based on computing the availability of each component, and second, the Markov model (MM) which is based on computing failure rate and repair rate of each component.
The study of this thesis is carried out on a 58.5 KWpgrid connected photovoltaic system. The PV array is modeled in the Simulink/MATLAB environment to estimate the maximum output power from the irradiance and temperature at a certain location. The irradiance and temperature are obtained over a period of three years with one hour time resolution and the obtained power is then clustered to ten different levels. This data is then input to an algorithm implemented in the MATLAB environment to estimate the reliability of different topologies using the SE and MM approaches. A useful comparison between the performance of different topologies has been made showing the advantages and disadvantages of each.
Keywords— Inverter, K-means clustering, Topologies, Photovoltaic (PV), Reliability, State enumeration, Mrkov model.
List of Contents
Statement I
Acknowledgment II
Abstract III
List of Contents V
List of Figures VIII
List of Tables X
List of Acronyms XI
List of Symbols XII
Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Research Objectives 6
1.3 Organization of the Thesis 7
Chapter 2 Grid Connected PV Systems: An Overview 9
2.1 General 9
2.2 PV System Components 9
2.2.1 PV Modules 11
2.2.2 DC-AC Power Inverter 13
2.2.3 DC-DC Converter 14
2.3 PV System Topologies 15
2.3.1 Centralized Topology 15
2.3.2 String Topology 16
2.3.3 Multi-String Topology 17
2.3.4 Master-Slave Topology 18
2.3.5 Micro-Converter Topology 19
2.4 Literature Review 20
Chapter 3 Reliability Parameters of PV System Components 24
3.1 General 24
3.2 General Reliability Parameters 25
3.3 Photovoltaic Array 27
3.4 Inverter 29
3.4.1 Failure Rate of Electronic Switch 30
3.4.2 Failure Rate of Diode 31
3.4.3 Failure Rate of Capacitor 37
3.5 DC-DC Converter 39
3.5.1 Failure Rate of Capacitor 39
3.5.2 Failure Rate of Electronic Switch 41
3.5.3 Failure Rate of Diode 42
3.5.4 Failure Rate of Inductor 43
3.6 Reliability Parameters of Other Components 45
Chapter 4 Reliability Assessment Methods 47
4.1 General 47
4.2 State Enumeration 47
4.3 Markov Model 51
Chapter 5 Reliability Indices for Different Topologies 56
5.1 General 56
5.2 Definitions 57
5.2.1 Ideal Supplied Energy (ISE) 57
5.2.2 Expected Supplied Energy (ESE) 57
5.2.3 Energy Availability (Ae) 58
5.2.4 Time Availability (At) 58
5.2.5 Available Hours (Tav) 58
5.2.6 Down Hours (Tdw) 59
5.2.7 Derated Hours (Tdr) 59
5.3 Centralized Topology 59
5.4 String Topology 65
5.5 Multi-String Topology 69
5.6 Master-Slave Topology 72
5.7 Micro-Converter Topology 76
Chapter 6 Simulations and Results 80
6.1 General 80
6.2 The PV Array 80
6.3 Results 90
Chapter 7 Conclusion and Future Work 98
7.1 Conclusion 98
7.2 Recommendations for Future Work 99
Appendix 101
Bibliography 102
Grid connected PV systems have several topologies with regards to their interface with the electric network. These include centralized, string, multi-string, master-slave and micro-converter topologies. These topologies differ from each other from the view point of cost and control.
The aim of this thesisis to perform a comparative study on the reliability of different topologies of grid connected photovoltaic (PV) systems. The reliability of each topology is investigated by considering the components of the system and their connection. Moreover, the impact of different environmental conditions, including irradiance and temperature, is considered in the analysis.
To perform the required analysis, suitable reliability indices that are based on calculating the probability of the different operating states are used.These states are evaluated using two different methods: first, the state enumeration method (SE) which is based on computing the availability of each component, and second, the Markov model (MM) which is based on computing failure rate and repair rate of each component.
The study of this thesis is carried out on a 58.5 KWpgrid connected photovoltaic system. The PV array is modeled in the Simulink/MATLAB environment to estimate the maximum output power from the irradiance and temperature at a certain location. The irradiance and temperature are obtained over a period of three years with one hour time resolution and the obtained power is then clustered to ten different levels. This data is then input to an algorithm implemented in the MATLAB environment to estimate the reliability of different topologies using the SE and MM approaches. A useful comparison between the performance of different topologies has been made showing the advantages and disadvantages of each.
Keywords— Inverter, K-means clustering, Topologies, Photovoltaic (PV), Reliability, State enumeration, Mrkov model.
List of Contents
Statement I
Acknowledgment II
Abstract III
List of Contents V
List of Figures VIII
List of Tables X
List of Acronyms XI
List of Symbols XII
Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Research Objectives 6
1.3 Organization of the Thesis 7
Chapter 2 Grid Connected PV Systems: An Overview 9
2.1 General 9
2.2 PV System Components 9
2.2.1 PV Modules 11
2.2.2 DC-AC Power Inverter 13
2.2.3 DC-DC Converter 14
2.3 PV System Topologies 15
2.3.1 Centralized Topology 15
2.3.2 String Topology 16
2.3.3 Multi-String Topology 17
2.3.4 Master-Slave Topology 18
2.3.5 Micro-Converter Topology 19
2.4 Literature Review 20
Chapter 3 Reliability Parameters of PV System Components 24
3.1 General 24
3.2 General Reliability Parameters 25
3.3 Photovoltaic Array 27
3.4 Inverter 29
3.4.1 Failure Rate of Electronic Switch 30
3.4.2 Failure Rate of Diode 31
3.4.3 Failure Rate of Capacitor 37
3.5 DC-DC Converter 39
3.5.1 Failure Rate of Capacitor 39
3.5.2 Failure Rate of Electronic Switch 41
3.5.3 Failure Rate of Diode 42
3.5.4 Failure Rate of Inductor 43
3.6 Reliability Parameters of Other Components 45
Chapter 4 Reliability Assessment Methods 47
4.1 General 47
4.2 State Enumeration 47
4.3 Markov Model 51
Chapter 5 Reliability Indices for Different Topologies 56
5.1 General 56
5.2 Definitions 57
5.2.1 Ideal Supplied Energy (ISE) 57
5.2.2 Expected Supplied Energy (ESE) 57
5.2.3 Energy Availability (Ae) 58
5.2.4 Time Availability (At) 58
5.2.5 Available Hours (Tav) 58
5.2.6 Down Hours (Tdw) 59
5.2.7 Derated Hours (Tdr) 59
5.3 Centralized Topology 59
5.4 String Topology 65
5.5 Multi-String Topology 69
5.6 Master-Slave Topology 72
5.7 Micro-Converter Topology 76
Chapter 6 Simulations and Results 80
6.1 General 80
6.2 The PV Array 80
6.3 Results 90
Chapter 7 Conclusion and Future Work 98
7.1 Conclusion 98
7.2 Recommendations for Future Work 99
Appendix 101
Bibliography 102
Other data
| Title | Reliability Assessment of Photovoltaic Generation Systems | Other Titles | تقييم اعتمادية أنظمة التوليد باستخدام الألواح الفوتوفولتية | Authors | Ahmed Mohamed Abdel Rahman Mustafa | Issue Date | 2016 |
Attached Files
| File | Size | Format | |
|---|---|---|---|
| G11354.pdf | 642.4 kB | Adobe PDF | View/Open |
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