This thesis presents a complete reliability, availability, and maintainability (RAM) analysis of the variable renewable energy (VRE) systems. Three operating concepts of the wind energy conversion systems (WECS) are considered based on the acceptable speed range of generators, while seven practical layouts of large-scale grid-connected systems are considered for the solar-PV systems. Elaborated RAM analysis of each system associated with each operating concept for the WECS and each layout of the solar-PV systems is presented starting from the subassemblies level to the subsystem level then the overall system.
This thesis is purposed to describe the method of reliability, availability, and maintainability analysis of repairable and non-repairable systems using the exponential PDFs. It is also aimed to explore the method for improving the availability of these systems by managing the effort using availability importance measures of each subassembly. This analysis will also be utilized to studying the criticality of the subassemblies or subsystems of the system in order to continuous improvement. After doing this, this thesis also extends to look into the overall system availability. This analysis is a good tool for helping to identify the critical subsystems or subassemblies of the system that need more attention for improvement.
Table of Contents
CHAPTER 1 : INTRODUCTION
1.1. RELIABILITY (RISK) ANALYSIS
1.2. RESEARCH PROBLEM
1.3. RESEARCH QUESTIONS
1.4. PURPOSE OF THIS THESIS
1.5. OBJECTIVE OF THIS THESIS
1.6. ORGANIZATION OF THE THESIS
CHAPTER 2 : RELIABILITY ENGINEERING OVERVIEW
2.1. RELIABILITY ENGINEERING
2.1.1. Basic RAM concepts
2.1.2. Hierarchy of the system
2.2. RAM ASSESSMENT OF VRE SYSTEMS
2.2.1. System decomposition
2.2.2. Reliability data collection
2.2.3. RAM modelling
CHAPTER 3 : PRACTICAL LAYOUTS OF SOLAR-PV AND WECS
3.1. SOLAR-PV SYSTEMS
3.2. WIND ENERGY CONVERSION SYSTEMS
CHAPTER 4 : HOLISTIC RAM EVALUATION OF WECS
4.1. INTRODUCTION
4.2. SURVEY AND ANALYSIS OF RAM FOR VARIOUS WTGS
4.2.1. System decomposition for WTGs
4.2.2. Reliability data collection for WTGs
4.2.3. Reliability modelling for WTGs
4.3. RAM RESULTS FOR VARIOUS WTGS
4.3.1. Reliability
4.3.2. Maintainability
4.3.3. Availability
4.4. WEIGHTING AND RANKING OF VARIOUS WTG SYSTEM
4.5. RAM COMPARISON BEFORE AND AFTER APPLYING THE WEIGHTS
4.6. FUZZY MODELING OF THE RAM FOR VARIOUS WECS
4.7. RAM ESTIMATE AND ANALYSIS
CHAPTER 5 : HOLISTIC RAM EVALUATION OF SOLAR-PV SYSTEMS
5.1. LITERATURE REVIEW OF SOLAR-PV SYSTEMS
5.2. SOLAR-PV SYSTEM DECOMPOSITION
5.3. RAM MODELLING
5.4. FAILURE AND REPAIR RATES OF SOLAR-PV SYSTEMS
5.5. RAM RESULTS FOR SUBASSEMBLIES OF SOLAR-PV SYSTEM
5.6. RAM RESULTS FOR SUBSYSTEMS OF SOLAR-PV SYSTEMS
5.7. BEST PDFS FOR SUB-ASSEMBLIES OF SOLAR-PV SYSTEMS
CHAPTER 6 : AVAILABILITY IMPORTANCE MEASURES
6.1. INTRODUCTION
6.2. CONCEPT OF AVAILABILITY IMPORTANCE MEASURES
6.3. AVAILABILITY IMPORTANCE MEASURES OF SOLAR-PV SYSTEMS
6.4. AVAILABILITY IMPORTANCE MEASURES OF WECS
CHAPTER 7 : DISCUSSION AND CONCLUSIONS
Objectives and Topics
This thesis aims to improve the system availability of variable renewable energy (VRE) systems by utilizing a detailed reliability, availability, and maintainability (RAM) analysis, addressing the challenges posed by their stochastic nature and the lack of robust field data.
- RAM analysis of Wind Energy Conversion Systems (WECS) with three operating concepts.
- RAM assessment of large-scale grid-connected solar-PV systems using seven practical layouts.
- Implementation of a novel statistical method using median values to increase result confidence.
- Development of Reliability Block Diagrams (RBD) and fuzzy set theory for evaluating system performance.
- Determination of availability importance measures to identify critical subsystems and prioritize maintenance.
Auszug aus dem Buch
1.1. Reliability (Risk) analysis
Reliability is the probability of a system or a subsystem or even subassembly/component to perform its function adequately, under the given operating conditions, for an intended period. This intended period is typically the lifetime of the system. The reliability of renewable sources seemed relatively lower than the conventional energy sources. This is due to the fact that these systems are usually operated in harsher environment. Therefore, the performance evaluation of renewable sources was considered the most important issue for the system planning and long-term operation, and was given a larger attention in reliability studies in recent times.
Generally, the performance of the renewable power plants depends on the availability of the primary resource, outside the variable renewable energy (VRE) system, and/or the availability of each plant subassemblies [10], inside the VRE system, as shown in Figure 1.1. Therefore, two trends have been taken in order to assess the reliability of the renewable systems in the relevant studies; reliability assessment of the system vulnerable components, and reliability evaluation of the whole systems considering the variable resources as illustrated in Figure 1.2. Although, the reliability issues have been identified since three decades, the reliability assessment of the whole power production is still under controversy due to the complex nature of these systems. The most literature focuses only on reliability assessment of the system vulnerable components (trend one) by different methods, whereas literatures that discussed the reliability evaluation of the whole systems (trend two) are much fewer. From reliability point of view, the main reason behind the lower reliability of the renewable systems is the higher failure rates of some subassemblies in the system [11]. Moreover, the system failure rate represents one of the main negative impacts on the overall cost of energy (CoE) where higher failure rates potentially lead to a higher CoE.
Summary of Chapters
CHAPTER 1 : INTRODUCTION: This chapter provides an overview of renewable energy systems, the research problem concerning their reliability, and the objectives and organization of the thesis.
CHAPTER 2 : RELIABILITY ENGINEERING OVERVIEW: This chapter covers fundamental RAM concepts, system hierarchy, and the methodology for assessing VRE systems including data collection and modelling.
CHAPTER 3 : PRACTICAL LAYOUTS OF SOLAR-PV AND WECS: This chapter examines various grid-connected and off-grid configurations for solar-PV and wind energy systems to select appropriate layouts for reliability analysis.
CHAPTER 4 : HOLISTIC RAM EVALUATION OF WECS: This chapter details the RAM evaluation of three wind turbine generator configurations, incorporating subassembly classification and fuzzy modeling.
CHAPTER 5 : HOLISTIC RAM EVALUATION OF SOLAR-PV SYSTEMS: This chapter presents a detailed RAM analysis for seven grid-connected solar-PV layouts and determines the best-fit probability distribution functions for subassembly failure rates.
CHAPTER 6 : AVAILABILITY IMPORTANCE MEASURES: This chapter introduces availability importance measures to evaluate and improve the performance of solar-PV and wind energy conversion systems.
CHAPTER 7 : DISCUSSION AND CONCLUSIONS: This chapter synthesizes the findings and provides conclusions based on the detailed reliability analysis conducted throughout the thesis.
Keywords
Reliability, Availability, Maintainability, Failure rate, Repair rate, VRE systems, Wind energy conversion systems, Solar-PV systems, RAM analysis, Fuzzy modeling, Reliability Block Diagram, Subsystem criticality, Maintenance strategy, WTG configurations, Energy storage.
Frequently Asked Questions
What is the primary focus of this thesis?
The thesis focuses on conducting a comprehensive reliability, availability, and maintainability (RAM) analysis for variable renewable energy systems, specifically solar-PV and wind energy conversion systems.
What are the central themes discussed in the work?
The central themes include system decomposition, data collection for subassemblies, reliability modeling using Reliability Block Diagrams (RBD), and the application of importance measures to optimize system availability.
What is the main objective or research question?
The main objective is to identify critical subsystems and subassemblies in renewable energy systems to improve overall system availability through targeted maintenance strategies and better reliability modeling.
What scientific methods are utilized in this research?
The research utilizes statistical analysis of field data using median values, Reliability Block Diagram (RBD) methods, and fuzzy set theory to represent input parameters and handle data uncertainties.
What is covered in the main body of the thesis?
The main body covers reliability engineering principles, practical system layouts for solar and wind power, detailed RAM evaluations for specific wind and solar configurations, and the application of importance measures.
Which keywords characterize this work?
The primary keywords are Reliability, Availability, Maintainability (RAM), Failure rate, Repair rate, and Variable Renewable Energy (VRE) systems.
How does the author address the problem of lacking robust data?
The author collects large amounts of reliability data from various wind farms and solar installations, then uses a novel statistical method to compute median values, which helps reduce uncertainties compared to using average values.
What is the role of fuzzy set theory in this thesis?
Fuzzy set theory is proposed as a method to overcome the difficulty of obtaining exact estimation of failure and repair rates by using triangular or trapezoidal fuzzy numbers to represent input parameters in the reliability models.
- Citar trabajo
- Doctor Ahmed Sayed (Autor), 2020, Reliability analysis of power systems with variable renewable resources, Múnich, GRIN Verlag, https://www.grin.com/document/922535
