Project topics and materials
Get Complete Project Material File(s) Now! »
Renewable energy based active generator
Introduction
Faced with the challenges of energy, the demand for primary energy in the world wide is evolving. However, the stock of oil in our planet will soon be exhausted. Today global warming becomes more serious due to the greenhouse effect. Some emissions of greenhouse gases come from the human activity. The production and processing of electrical energy is one of the main sources of greenhouse gases. For reducing the greenhouse gas emission and assuring the energy security, renewable energy is promoted in the electrical power production.
However, an electrical generating system depending entirely on the renewable energy sources is not reliable because the availability of the renewable energy sources can not be constantly assured.
In this report a hybrid active generator is proposed to deal with the problem of the renewable energy intermittent power. A hybrid power system combing the renewable energy sources and the storage units can be considered as an active generator, which can provide the power that is demanded by the grid operator. Integrating photovoltaic power sources with batteries as storage, can lead to a long-term reliable energy source. The ultra-capacitors have fast dynamics, thus can be used to smooth fast fluctuations of the photovoltaic power and can ensure a good power quality.
In this chapter, different forms of renewable energy and different kinds of electrical storage technologies will be presented. A hybrid system based on PV panels, lead acid batteries and ultracapacitors will be proposed. In the end of this chapter, each source inside this hybrid generator is modeled.
Renewable energy
Renewable energy is the energy generated from natural resources. Renewable energy flows involve natural phenomena such as sunlight, wind, tides and geothermal heat, as the International Energy Agency explains:
“Renewable energy is derived from natural processes that are replenished constantly. In its various forms, it derives directly from the sun or from heat generated deep within the earth.
It includes the electricity and the heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources and bio-fuels and hydrogen derived from renewable resources” [IEA 03].
Benefits of renewable energy
The potential contribution of renewable energies to IEA member countries (United Kingdom, Germany, France, United States, Japan…) is growing, as the technologies mature and there is an increasing awareness about the full contribution that renewable energies can make. Renewable energy sources contribute to the diversity of the energy supply portfolio and reduce the risks of continued (or expanded) use of fossil fuels and nuclear power. Distributed renewable energies provide options to consumers because of their deployment close to use.
Renewable energy is also the most environmentally benign energy supply option available in current and near-term markets. Finally, renewable energies contribute to a healthy economy, both in their contribution to the efficiency of the energy system, and in the employment and investment opportunities that arise from continued rapid market growth [URL 06b].
The primary benefits to us are the energy security, the environment protection and the economic growth.
Energy security
Faced with the energy challenges, the demand for primary energy in the world wide is evolving, particularly in fast developing countries like China. However, the stock of oil in our planet will soon be exhausted. Such dependency over an extended period is unsustainable.
Renewable energy can relieve some of that increasing need for imported fossil fuels and reduce dependence on foreign sources.
The distributed capability of renewable energies brings the electrical production closer to the end-use, thus minimizing energy transport concerns and costs. The Renewable Energy Working Party also believes that a greater use of renewables in the energy portfolio can minimize overall generation costs relative to the risk [IEA 03]. Energy policies should focus on developing efficient generating portfolios that do not solely rely on stand-alone costs but also on expected portfolio risk, including year-to-year cost fluctuations.
Environment protection
Moreover, today global warming becomes more serious due to the greenhouse effect.
Some emissions of greenhouse gases come from the human activity. The production and processing of electrical energy is one of the main sources of greenhouse gases. Directly or indirectly, environmental concerns dominate the thrust for an expanded deployment of renewable energy technologies. Climate change concerns, which arose during the late 1980s, have created a new input for clean, low-carbon energy technologies, such as renewable energy technologies. In December 1997, the Kyoto protocol has been established in order to reduce global emissions of greenhouse gases. In the area of power generation, this protocol promotes renewable energy sources [KYO 09].
Economic growth
Renewable energy has several important economic benefits. In IEA (International Energy Agency) countries, the main economic benefits are employment creation and increased trade of technologies and services.
Dispatchable renewable energy based generators
The renewable energy based generation can be divided into two kinds: dispatchable production and non-dispatchable production. Dispatchable production refers to sources of electricity that can be dispatched at the request of power grid operators. They are able to change their power production upon demand.
Water power
Water power can be exploited in a form of kinetic energy. Since water is about 800 times denser than air, a slow flowing stream of water can yield considerable amounts of energy.
Water power exists in many forms. Hydroelectric energy is a term, which is usually reserved for large-scale hydroelectric dams. Micro hydro systems are hydroelectric power installations that typically produce up to 100 kW of power, which are often used in water rich areas as a Remote Area Power Supply. Ocean energy describes all the technologies to harness energy from the ocean and the sea including marine current power, ocean thermal energy conversion, wave power and etc.
Biofuel
Plants use photosynthesis to grow and produce biomass. Also known as biomatter, biomass can be used directly as fuel or to produce biofuels. Agriculturally produced biomass fuels, such as biodiesel, ethanol and bagasse (often a by-product of sugar cane cultivation) can be burned in internal combustion engines or boilers. Typically biofuel is burned to release its stored chemical energy.
Geothermal energy
Geothermal energy is from the heat of the earth itself, both from kilometers deep into the Earth’s crust in some places of the globe or from some meters in geothermal heat pump in all the places of the planet. Geothermal technology is mostly used for thermal power production, the space heating is becoming increasingly important. Geothermal electricity production is a base load technology, and can be a low-cost option if the hot water or steam resource is at a high temperature and near the earth’s surface.
Non-dispatchable renewable energy based generators
Wind power
Wind energy is considered as one of the most promising technologies for electricity production and the costs, with good wind regimes, are comparable to fossil alternatives, particularly when the environmental benefit is considered. Airflow can run wind turbines for generating electricity. The rated power of modern wind turbines ranges from 600 kW to 5 MW [EWE 07]. The power output of a turbine depends on the wind speed and so, as the wind speed increases, the power output increases. The location of wind turbine installation is usually chosen in the areas where winds are strong and constant, such as offshore and high altitude sites. Offshore resources experience have shown that mean wind speeds are about 90% greater in onshore, so offshore resources may contribute more significantly to the supply of energy. Globally, the long-term technical potential of wind energy is believed to be five times equal to the total current global energy production, or equal to the 40 times current electricity demand [URL 06a].
Solar power
Solar energy comes from the radiant light and heat of the sun. Sunlight can be converted directly into electricity by using PhotoVoltaic (PV) panels or indirectly with Concentrating Solar Power (CSP). CSP normally focuses the sun’s energy to boil water, which is then used to provide electrical power. Photovoltaic (PV) technologies use semiconductor materials to convert sunlight directly into electricity. They have dropped in price to between one-third and one-fifth their cost in 1980 [URL 06b]. PV is now widely viewed as cost competitive for many grid-connected, building-integrated uses and for off-grid applications as in telecommunications, power supply of village power.
Renewable energy development
Today different kinds of renewable energy technologies have been established in world markets. Some renewable energy technologies are becoming quickly competitive in growing markets, and some are widely recognized as the lowest cost option for stand-alone and offgrid applications. The capital costs of certain renewable energy technologies have been obviously reduced over the last decade and it is possible to be halved again over the next decade.
From the end of 2004 to the end of 2008, the PV power has increased six times and now is more than 16 Gigawatts (GW), wind power capacity has increased 250 percent to 121 GW, and the total power capacity from new renewable energies has increased to 75 percent to 280 GW (Figure I.1) [URL 09a].
The IEA’s World Energy Outlook 2000 (WEO 2000), in its reference case, estimates that the non-hydro share of renewables will grow from the current 2 percents of TPES (Total Primary Energy Supply) to 4 percents of TPES by 2020 in the OECD (Organization for Economic Cooperation and Development) region. Non-hydro renewables are expected to be the fastest growing primary energy sources, with an annual growth rate averaging 2.8 per cent over the outlook period. Throughout the world, hydroelectricity is expected to increase by 50 per cent between 2000 and 2020, even though its overall share of TPES will decrease. More than 80 per cent of the increase will take place in developing countries [REN 09].
Table of contents :
General introduction
Chapter I. Renewable energy based active generator
I.1. Introduction
I.2. Renewable energy
I.2.1. Benefits of renewable energy
I.2.2. Dispatchable renewable energy based generators
I.2.3. Non-dispatchable renewable energy based generators
I.2.4. Renewable energy development
I.2.5. Constraints
I.3. Energy storage
I.3.1. Different kinds of energy storage
I.3.2. Long term energy storage and fast dynamic power storage
I.4. Hybrid power generator
I.4.1. Interest
I.4.2. Configuration of an hybrid power generator
I.4.3. Structure of the studied hybrid power generator
I.5. Modeling of the studied hybrid power generator
I.5.1. Presentation
I.5.2. PV panels
I.5.3. Lead-acid battery
I.5.4. Ultracapacitor
I.6. Conclusion
Chapter II. Control system of the active PV generator
II.1. Introduction
II.2. Modeling of the PV active generator
II.2.1. Methods
II.2.2. PV power conversion system
II.2.3. Batteries energy storage system
II.2.4. Ultracapacitors
II.2.5. Grid connection
II.2.6. DC bus
II.2.7. Modeling of the entire PV energy conversion system
II.3. Control of the active PV generator
II.3.1. Hierarchical control structure
II.3.2. Automatic Control unit
II.3.3. Power control unit
II.4. Power balancing strategies for the active PV generator
II.4.1. Role of the DC bus
II.4.2. Normal mode
II.4.3. PV limitation mode
II.4.4. Disconnection mode
II.4.5. Synthesis
II.5. Control of operating modes
II.6. Energy management of the embedded ultracapacitors
II.6.1. Energy level and management scheme
II.6.2. Full ultracapacitors mode
II.6.3. Empty ultracapacitors mode
II.7. Simulation and experimental results
II.7.1. Simulation results
II.7.2. Experimental results
II.8. Conclusions
Chapter III. Micro Grid framework for integrating DG in energy management and control system of power network
III.1. Introduction
III.2. Architecture of future electrical systems
III.2.1. Issues
III.2.2. Interest of micro grids and specificities
III.2.3. Basic MG architectures
III.2.4. Operation modes
III.3. State of the art
III.3.1. In Europe
III.3.2. In the United States
III.3.3. In Japan
III.4. Dispatchable distributed generation for grid control
III.4.1. Interest
III.4.2. Classical isochronous speed control of conventional DGs….
III.4.3. Energy storage requirements in power systems
III.4.4. Control functions for grid connected inverters
III.4.5. Control strategies for a grid-connected mode of the microgrid
III.4.6. Control strategies for a “Vf mode” in an islanded mode of the microgrid
III.4.7. Control capabilities of the PV based active generator
III.5. Control system for microgrids
III.5.1. Objectives and tasks
III.5.2. Communication system
III.5.3. Control functions and management tasks
III.5.4. Time scale analyzing and implementation constraints
III.5.5. Power management by sensing electrical quantities
III.5.6. Energy management by signal communication
III.6. Conclusion
Chapter IV. Planning and energy management system of a residential micro grid
IV.1. Introduction
IV.2. Residential network application
IV.2.1. Integration of the active generator in a home
IV.2.2. Residential network and electrical system organization
IV.2.3. Application of microgrid concepts and global objective
IV.2.4. Microgrid energy management
IV.3. Forecasting techniques and processing of data
IV.3.1. PV power prediction
IV.3.2. Load forecasting
IV.3.3. Energy estimation
IV.4. Daily power planning / Setting of half-hour power references
IV.4.1. Objectives
IV.4.2. Constraints
IV.4.3. Determinist algorithm
IV.4.4. Practical application
IV.5. Medium-term energy management
IV.5.1. Reduction of the uncertainty (MGCC)
IV.5.2. Energy management of batteries (LC)
IV.6. Short-term power management
IV.6.1. Primary frequency regulation
IV.6.2. Power balancing strategies for the active generator
IV.7. Experimental tests through Hardware in the Loop simulations
IV.7.1. Description of the experimental platform
IV.7.2. Analysis of the self consumption of one house
IV.7.3. Increasing the penetration ratio in a residential network
IV.8. Conclusions
General conclusion
Appendix
General Bibliography
