Description
ABSTRACT
The integration of solar power into electricity grids is presented in this work. Integration technology has become important due to the world’s energy requirements which imposed significant need for different methods by which energy can be produced or integrated, in addition to the fact that integration of solar energy into non-renewable sources is important as it reduces the rates of consuming of non-renewable resources hence reduce dependence of fossil fuels. Photovoltaic or PV system are leading this revolution by utilizing the available power of the sun and transforming it from DC to AC power. Integrating renewable energy of this source into grids has become prominent amongst researchers and scientists due to the current energy demand together with depletion of fossil-fuel reserves and environmental impacts. In this work, current solar-grid integration technologies are identified and discussed, benefits of solar-grid integration are highlighted, solar system characteristics for integration and the effects and challenges of integration are discussed. Integration issues and compatibility of both systems (i.e. solar and grid generations) are addressed from both the solar system side and from utility side. This work will help in the implementation of solar-grid integration study.
TABLE OF CONTENTS
TITLE PAGE
APPROVAL PAGE
DEDICATION
ACKNOWLEDGEMENT
ABSTRACT
TABLE OF CONTENT
CHAPTER ONE
- INTRODUCTION
- BACKGROUND OF THE PROJECT
- PROBLEM STATEMENT
- AIM AND OBJECTIVE OF THE PROJECT
- SCOPE OF THE PROJECT
- BENEFIT OF THE PROJECT
- SIGNIFICANCE OF THE PROJECT
- PROJECT ORGANIZATION
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 REVIEW OF RELATED STUDIES
2.3 SOLAR POWER GENERATION
2.3 SOLAR-GRID SYSTEM
2.4 CHALLENGES, BENEFITS AND ENVIRONMENTAL IMPACT OF SOLAR-GRID INTEGRATION
2.5 ELECTRICAL GRID
CHAPTER THREE
3.0 METHODOLOGY
3.1 SYSTEM DESCRIPTION
3.2 SCHEMATIC DIAGRAM OF THE SYSTEM
3.3 SYSTEM WIRING DIAGRAM
3.4 GRID CONNECTED NET METERING
CHAPTER FOUR
RESULT ANALYSIS
4.0 SOLAR ENERGY GRID CONNECTION REQUIREMENTS
4.1 Point of common coupling
4.2 Range of voltage
4.3 Frequency range
4.4 Starting up solar power plants
4.5 Power quality requirements
4.6 Harmonic distortion
4.7 Limits of flicker severity
4.8 Limits of voltage fluctuations
CHAPTER FIVE
- CONCLUSIONS AND RECOMMENDATION
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Solar-grid integration is a network allowing substantial penetration of Photovoltaic (PV) power into the national utility grid. This is an important technology as the integration of standardized PV systems into grids optimizes the building energy balance, improves the economics of the PV system, reduces operational costs, and provides added value to the consumer and the utility according to Sterling et al, [2013]. Solar-grid integration is now a common practice in many countries of the world; as there is a growing demand for use of alternative clean energy as against fossil fuel [ Akubude et al, 2019]. Global installed capacity for solar-powered electricity has seen an exponential growth, reaching around 290 GW at the end of 2016. According to IRENA’s Renewable Energy Capacity Statistics (2017), currently China is the leading producer of solar power followed by Japan, Germany, and United States. Also, solar installed capacity by region has Europe leading with over 98.8 GW, closely followed by Asia with 92.3 GW. Africa is least in solar installed capacity with about 1.92 GW (Volkmar et al, 2013). However, Africa is highly abundant in solar radiation with most of the African countries receiving a very high amount of bright sunlight resource of days per year that can be used for electricity generation. Notable areas include the deserts of North & West Africa like Egypt, Nigeria and some parts of Southern and East Africa which receive long periods of sunny days with a very high intensity of irradiation. According to the IRENA’s Renewable Energy Capacity Statistics (2017), Africa has nearly reached a total solar Photovoltaic capacity of 2.5 GW, representing less than 1.16% of the world’s solar capacity of 290 GW. In South Africa, the majority of its territory receives in excess of 2500 h of sunshine per year, and has average solar radiation levels ranging from 4.5 to 6.5 kWh/m2/day with an annual 24-hour global solar radiation average of about 220 W/m2 [Bookmark, 2013]. The country is considered to have a high solar energy potential. In the neighboring Botswana, according to the World Energy council report (2016), Botswana receives a high rate of solar insolation of approximately 280–330 days of sun per year with daily average sunshine ranging from 9.9 h during the summer to 8.2 h in winter. The average total solar radiation is approximately 2100 kWh/m2/yr. However, the country’s available resource is currently under-utilized. It is mainly used for domestic solar water heating but PV technology is also used for small-scale generation systems [Volkmar, 2013]. Egypt is another country located in the world’s solar belt and therefore has an excellent solar availability. According to WEC [Bookmark, 2013], average solar radiation ranges from about 1950 kWh/m2/yr on the Mediterranean coast to more than 2600 kWh/m2/yr in Upper Egypt, while about 90% of the Egyptian territory has an average global radiation greater than 2200 kWh/m2/yr. Egypt’s first concentrating solar power (CSP) plant project at Mayoralty, 90 km south of Cairo, is estimated to include two gas turbines of approximately 40 MW each, and a 70 MW steam turbine. The overall output capacity is estimated to be around 140 MW [Bookmark, 2013].
Solar-grid integration technology include advanced inverters technology, anti-islanding technology, grid-plant protection technology, solar-grid forecasting technology and smart grids technology. Inverter ranges from Light duty inverters typically (100–10,000 W), Medium duty inverters typically (500–20,000 W), Heavy duty inverters typically (10,000–60,000 W) continuous output. Energy created by the solar array powers the loads directly, with any excess being sent to the utility, resulting in net metering [Volkmar, 2013]. Due to this interaction with the grid, inverters are required to have anti-islanding protection, meaning they must automatically stop power flow when the grid goes down [ Hoke et al, 2016]. Currently, advanced inverters devices that convert direct current solar power into alternating current power for the grid have features that could be used to help control voltage and make the grid more stable. During manufacturing inverters are validated their advanced photovoltaic (PV) capacities by using the ESIF’s power hardware-in-the-loop system and megawatt-scale grid simulators. During simulation inverters are put into a real-world simulation environment and see the impact of the inverter’s advanced features on power reliability and quality [NREL, 2012].
Islanding is the phenomena in which a PV power distributed continues to power the grid even though electrical grid power is no longer present. According to IEEE 1547 Section 4, PV system power must be de-energized from the grid within two seconds of the formation of an island; this means PV Plant interconnection system shall detect the island and cease to energize the grid within two seconds of the formation of an island. Further, the inverter must not connect within 60 s of the grid re-establishing power supply after a power failure, sometimes called Re connection Timing Test [Hoke, 2016]. This is often achieved through autonomous island detection controls. Such controls use one or more of a wide variety of active or passive methods to detect an island. Normally grid tie Inverters undergoes anti-islanding tests during manufacturing to check whether they connects and disconnects to the broader electricity grid safely [NREL, 2011].
An additional new requirement concerns grid and plant protection (G/P protection). This is the protective device that monitors all relevant grid parameters and disconnects the plant from the grid, if necessary. A freely accessible disconnection point for plants with more than 30 kVA of apparent power is no longer required, but more extensive grid monitoring including the power frequency and single error safety is usually stipulated [Scientists, 2015]. Plants with less than 30 kVA of apparent power may still be operated with G/P protection integrated in the inverter. If all inverters include separate stand-alone grid detection with grid disconnection via the tie breaker integrated in the device, separate stand-alone grid detection may be omitted in the central G/P protection. This solution is a considerable cost-saver and is possible with all SMA inverters [ Scientists, 2015].
Renewable energy source integration with power systems is one of the main concepts of smart grids. Due to the variability and limited predictability of these sources, there are many challenges associated with integration. This paper reviews integration of solar systems into electricity grids. The approach in is focused on integrating Photovoltaics (PV) system to electricity grids. Attention is focused on inverter technology since the harmonization problem comes mainly from power inverters used in converting solar generated DC voltage into AC. Solar power as one of the renewable energy also has environmental impacts, some of which are significant. This work described the integration of photovoltaic power plant with power system grid.
1.2 PROBLEM STATEMENT
Power supply has been one of the major problems facing developing countries like Nigeria. Currently, transmission systems are reaching their maximum supply capacity because of the huge amount of power to be transferred. Therefore, power utilities have to invest a lot of money to expand their facilities to meet the growing power demand and to provide uninterrupted power supply to industrial and commercial customers [Akubude, 2019]. This includes the integration of solar energy with power grid to improve power quality.
1.3 AIM AND OBJECTIVES OF THE STUDY
The main aim of this work is to carry out an analysis and control of the power grid with grid scale PV-based power generations as well as of various consequences of grid scale integration of PV generation units into the power systems.
The objectives of this work are:
- To integrate renewable energy to power system
- To alternative way to support power demand and overcome congested transmission lines
- upgraded transmission and distribution infrastructure
- improved utility system reliability
1.4 SCOPE OF THE STUDY
The scope of this study covers the measurement campaigns on power quality analyses and the examination of grid stability of electric networks with high penetration of photovoltaic (PV) generation. The paper shall also summarize information on the current knowledge and previous experiments with these systems to identify areas for further investigation and technology enhancement that enable development of high penetration PV networks.
1.5 BENEFIT OF THE STUDY
The introduction of photovoltaic based distributed generation units in the distribution system may lead to several benefits such as voltage support, improved power quality, loss reduction, deferment of new or upgraded transmission and distribution infrastructure, and improved utility system reliability.
1.6 SIGNIFICANCE OF THE STUDY
This work will serve as a means of teaching the student involved on how renewable energy can be integrated with power grid to supply a constant power to the country. Finally, it will also serve as a useful piece of information for both pv installers and electrical engineers.
1.7 PROJECT ORGANIZATION
The work is organized as follows: chapter one discuses the introductory part of the work, chapter two presents the literature review of the study, chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.
CHAPTER FIVE
5.1 CONCLUSION AND RECOMMENDATION
Integrating PV system into national grids can reduce transmission and distribution line losses, increase grid resilience, lower generation costs, and reduce requirements to invest in new utility generation capacity. The goal of this paper was to review the current and future discussions regarding generation and integration of large-scale solar generation into a conventional fossil-fuel dominated grid. Most of the research has shown positive results on integration. The effects of this integration on system stability and security should therefore be considered carefully even before installations of plant. The use of advanced integration technologies should be considered before plant installation, this will help the generation and distribution company to foresee the possible impact of PV integration and generation on system stability.
Living with a grid connected solar PV system is no different than living with just the normal grid power, except that some or all of the electricity that is consumed comes from the sun. PV solar systems designed for grid connection are usually designed to meet at least half of home owners electrical needs.
Purchasing a home solar photovoltaic panel array large enough to supply the entire electrical needs of a home would be extremely expensive with the solar array taking up a large amount of space. The solar power generated by a grid connected system is therefore only partial, with the remaining energy being made up by the power company.
The advantage of a Grid Connected PV System, either with or without storage batteries is that on clear blue sunny days, when the photovoltaic system is producing large amounts of current and the home is consuming low energy levels, for example, if you are out of your home all the day working, you’re solar system keeps generating electricity. The excess electricity generated does not go to waste but is fed back into the power grid to be used by your neighbouring homes who unknowingly end up using the clean, renewable energy themselves while making money for you through your “net metering” arrangement.
