In the present era, due to increased power demand to meet up the industrial requirements, the shortfalls in power generation have been attempted to mitigate between supply and demand through developments of National Grid connected systems where all the national power generation sources are connected to National grid and on the basis of the zonal requirement, the energy management is implemented. An “electricity grid” is not a single entity but an aggregate of multiple networks and multiple power generation companies with multiple operators employing varying levels of communication and coordination, most of which is manually controlled .
With this concept, the earlier power shortage has been to some extent equated and is able to control the transmission losses and improve the transmission efficiency to some extent. This contrasts with 60 percent efficiency for grids based on the latest technology which may be the solution for the above problem: SMARD GRID TECHNOLOGIES.
To implement systematically the energy requirement for different zones, it necessarily requires a strategic program of distribution of energy. SCADA and other continuously monitoring systems though in vogue but for quick effective and efficient distribution of energy needs, a smart system which can take into account the requirements of the zones and the availability of energy from the different sources in the zones is required without human interference. Smart grids increase the connectivity, automation and coordination between these suppliers, consumers and networks that perform either long distance transmission or local distribution tasks.
Brief History of Smart Grid
Commercialization of electric power began early in the 21th century. With the light bulb revolution and the promise of the electric motor, demand for electric power exploded, sparking the rapid development of an effective distribution system. At first, small utility companies provided power to local industrial plants and private communities. Some larger businesses even generated their own power. Seeking greater efficiency and distribution, utility companies pooled their resources, sharing transmission lines and quickly forming electrical networks called grids. George Westinghouse boosted the industry with his hydroelectric power plant in Niagara Falls. His was the first to provide power over long distances, extending the range of power plant positioning. He also proved electricity to be the most effective form of power transmission. As the utility business expanded, local grids grew increasingly interconnected, eventually forming the three national grids that provide power to nearly every denizen of the continental US. The Eastern Interconnect, the Western Interconnect, and the Texas Interconnect are linked themselves and form what we refer to as the national power grid. Technological improvements of the power system largely raised in the 51s and 61s, post World War II. Nuclear power, computer controls, and other developments helped fine tune the grid’s effectiveness and operability. Although today’s technology has flown light-years into the future, the national power grid has not kept up pace with modernization. The grid has evolved little over the past fifty years.
The government is keen on overhauling the current electrical system to 21st century standards. With today’s technology, the power grid can become a smart grid, capable of recording, analyzing and reacting to transmission data, allowing for more efficient management of resources, and more cost-effective appliances for consumers. This project requires major equipment upgrades, rewiring, and implementation of new technology. The process will take time, but improvements have already begun to surface. Miami will be the first major city with a smart grid system. We are witnessing a new stage of technological evolution, taking us into a brighter, cleaner future.
Smart grid technologies have emerged from earlier attempts at using electronic control, metering, and monitoring. In the 1981s, Automatic meter reading was used for monitoring loads from large customers, and evolved into the Advanced Metering Infrastructure of the 1991s, whose meters could store how electricity was used at different times of the day. Smart meters add continuous communications so that monitoring can be done in real time, and can be used as a gateway to demand response-aware devices and “smart sockets” in the home. Early forms of such Demand side management technologies were dynamic demand aware devices that passively sensed the load on the grid by monitoring changes in the power supply frequency. Devices such as industrial and domestic air conditioners, refrigerators and heaters adjusted their duty cycle to avoid activation during times the grid was suffering a peak condition. Beginning in 2111, Italy’s Telegestore Project was the first to network large numbers (27 million) of homes using such smart meters connected via low bandwidth power line communication. Recent projects use Broadband over Power Line (BPL) communications, or wireless technologies such as mesh networking that is advocated as providing more reliable connections to disparate devices in the home as well as supporting metering of other utilities such as gas and water.
Monitoring and synchronization of wide area networks were revolutionized in the early 1991s when the Bonneville Power Administration expanded its smart grid research with prototype sensors that are capable of very rapid analysis of anomalies in electricity quality over very large geographic areas. The culmination of this work was the first operational Wide Area Measurement System (WAMS) in 2111. Other countries are rapidly integrating this technology China will have a comprehensive national WAMS system when its current 5-year economic plan is complete in 2112.
First Cities with Smart Grids
The earliest, and still largest, example of a smart grid is the Italian system installed by Enel S.p.A. of Italy. Completed in 2115, the Telegestore project was highly unusual in the utility world because the company designed and manufactured their own meters, acted as their own system integrator, and developed their own system software. The Telegestore project is widely regarded as the first commercial scale use of smart grid technology to the home, and delivers annual savings of 511 million euro at a project cost of 2.1 billion euro.
In the US, the city of Austin, Texas has been working on building its smart grid since 2113, when its utility first replaced 1/3 of its manual meters with smart meters that communicate via a wireless mesh network. It currently manages 211,111 devices real-time (smart meters, smart thermostats, and sensors across its service area), and expects to be supporting 511,111 devices real-time in 2119 servicing 1 million consumers and 43,111 businesses. Boulder, Colorado completed the first phase of its smart grid project in August 2118. Both systems use the smart meter as a gateway to the home automation network (HAN) that controls smart sockets and devices. Some HAN designers favor decoupling control functions from the meter, out of concern of future mismatches with new standards and technologies available from the fast moving business segment of home electronic devices.
Hydro One, in Ontario, Canada is in the midst of a large-scale Smart Grid initiative, deploying a standards-compliant communications infrastructure from Trilliant. By the end of 2111, the system will serve 1.3 million customers in the province of Ontario. The initiative won the “Best AMR Initiative in North America” award from the Utility Planning Network. The City of Mannheim in Germany is using real time Broadband Power line (BPL) communications in its Model City Mannheim “MoMa” project adelaide in Australia also plans to implement a localized green Smart Grid electricity network in the Tonsely Park redevelopment.
InovGrid is an innovative project in Evora that aims to equip the electricity grid with information and devices to automate grid management, improve service quality, reduce operating costs, promote energy efficiency and environmental sustainability, and increase the penetration of renewable energies and electric vehicles. It will be possible to control and manage the state of the entire electricity distribution grid at any given instant, allowing suppliers and energy services companies to use this technological platform to offer consumers information and added-value energy products and services. This project to install an intelligent energy grid places Portugal and EDP at the cutting edge of technological innovation and service provision in Europe.
Smart Grid Definition
A SMART GRID delivers electricity from supplier to consumers using two- way digital technology to control appliances at consumers’ homes to save energy, reduce cost and increase reliability and transparency. It overlays the electricity distribution grid with an information and net metering system. Power travels from the power plant to our house through an amazing system called the power distribution grid. Such a modernized electricity networks is being promoted by many governments as a way of addressing energy independences, global warming and emergency resilience issues. Smart meters may be part of smart grid, but alone do not constitute a smart grid.
A smart grid includes an intelligent monitoring system that keeps track of all electricity flowing in the system. It also incorporates the use of superconductive transmission lines for less power loss, as well as the capability of the integrating renewable electricity such as solar and wind. When power is least expensive the user can allow the smart grid to turn on selected home appliances such as washing machines or factory processes that can run at arbitrary hours. At peak times it could turn off selected appliances to reduce demand. The smart grid is able to respond appropriately to different types of incidents, such as weather issues or failing equipment. The smart grid can identify a piece of failing equipment (or even find a tree branch that’s fallen on an electrical line) and alert the Provider. Conversely, the smart grid can extend the life of some equipment: Today, some Providers automatically replace equipment once it reaches a certain age, whether it’s worn out or not. With a smart grid, equipment could remain in operation until a computer detects its failure, thereby saving unnecessary replacement costs. In some cases the smart grid can solve power outages and other service interruptions. When the smart grid overlays the electrical grid, computerized devices monitor and adjust the quality and flow of power between its sources and its destinations. These devices recognize situations such as peak usage hours, when most people are in their homes. The devices can also detect energy-wasting appliances.
In short, the smart grid is the development of a reliable network of transmission and distribution lines that allow new technologies, equipment, and control systems to be easily integrated into an energy grid.
Smart Grid and its Need
Understanding the need for smart grid requires acknowledging a few facts about our infrastructure. The power grid is the backbone of the modern civilization, a complex society with often conflicting energy needs-more electricity but fewer fossil fuels, increased reliability yet lower energy costs, more secure distribution with less maintenance, effective new construction and efficient disaster reconstruction. But while demand for electricity has risen drastically, its transmission is outdated and stressed. The bottom line is that we are exacting more from a grid that is simply not up to the task.
Aims of the Smart Grids-the Vision
- Provide a user-centric approach and allow new services to enter into the market;
- Establish innovation as an economical driver for the electricity networks renewal;
- Maintain security of supply, ensure integration and interoperability;
- Provide accessibility to a liberalized market and foster competition;
- Enable distributed generation and utilization of renewable energy sources;
- Ensure best use of central generation;
- Consider appropriately the impact of environmental limitations;
- Enable demand side participation (DSR, DSM);
- Inform the political and regulatory aspects;
- Consider the societal aspects.
Key Features of Smart Grid
- Intelligent – Capable of sensing system overloads and rerouting power to prevent or minimize a potential outage; of working autonomously when conditions required resolution faster than humans can respond and co-operatively in aligning the goals of utilities, consumers and regulators.
- Efficient – Capable of meeting efficient increased consumer demand without adding infrastructure.
- Accommodating – Accepting energy from virtually any fuel source including solar and wind as easily and transparently as coal and natural gas: capable of integrating any and all better ideas and technologies – energy storage technologies. For e.g. – as they are market proven and ready to come online.
- Motivating – Enable real-time communication between the consumer and utility, so consumer can tailor their energy consumption based on individual preferences, like price and or environmental concerns.
- Resilient – Increasingly resistant to attack and natural disasters as it becomes more decentralization and reinforced with smart grid security protocol.
- Green – Slowing the advance of global climate change and offering a genuine path towards significant environmental improvement.
- Load Handling – The sum/total of the power grid load is not stable and it varies over time. In case of heavy load, a smart grid system can advise consumers to temporarily minimize energy consumption.
- Demands Response Support – Provides users with an automated way to reduce their electricity bills by guiding them to use low-priority electronic devices when rates are lower.
- Decentralization of Power Generation – A distributed or decentralized grid system allows the individual user to generate onsite power by employing any appropriate method at his or her discretion.
- It can repair itself.
- It encourages consumer participation in grid operations.
- It ensures a consistent and premium-quality power supply that resists power leakages.
- It allows the electricity markets to grow and make business.
The Key Challenges for Smart Grids
- Strengthening the grid: ensuring that there is sufficient transmission capacity to interconnect energy resources, especially renewable resources.
- Moving offshore: developing the most efficient connections for offshore wind farms and for other marine technologies.
- Developing decentralized architectures: enabling smaller scale electricity supply systems to operate harmoniously with the total system.
- Communications delivering the communications infrastructure to allow potentially millions of parties to operate and trade in the single market.
- Active demand side: enabling all consumers, with or without their own generation, to play an active role in the operation of the system.
- Integrating intermittent generation: finding the best ways of integrating intermittent generation including residential micro generation.
- Enhanced intelligence of generation, demand and most notably in the grid.
- Preparing for electric vehicles: whereas Smart Grids must accommodate the needs of all consumers, electric vehicles are particularly emphasized due to their mobile and highly dispersed character and possible massive deployment in the next years, what would yield a major challenge for the future electricity networks.
The earliest, and still largest, example of a smart grid is the Italian system installed by Enel S. p. A. of Italy.
Making the Power Grid Smart
The utilities get the ability to communicate with and control end user hardware, from industrial- scale air conditioner to residential water heaters. They use that to better balance supply and demand, in part by dropping demand during peak usage hours. Taking advantages of information technology to increase the efficiency of the grid, the delivery system, and the use of electricity at the same time is itself a smart move. Simply put, a smart grid combined with smart meters enables both electrical utilities and consumer to be much more efficient.
A smart grid not only moves electricity more efficiently in geographic terms, it also enables electricity use to be shifted overtime-for example, from period of peak demand to those of off-peak demand. Achieving this goal means working with consumers who have “smart meters” to see exactly how much electricity is being used at any particular time. This facilitates two-way communication between utility and consumer. So they can cooperate in reducing peak demand in a way that it’s advantageous to both. And it allow to the use of two ways metering so that customer who have a rooftop solar electric panel or their own windmill can sell surplus electricity back to the utility.
Status of the Smart Grid According to the Department of Energy
The DOE has just released a state of the smart grid report as part of a directive in the Energy Independence and Security Act of 2117 that tells the Secretary of Energy to “report to Congress concerning the status of smart grid deployments nationwide and any regulatory or government barriers to continued deployment.” So, here we have it. The report as a whole is a really interesting and worth a full read, but key findings include:
Distributed energy resources
The ability to connect distributed generation, storage, and renewable resources is becoming more standardized and cost effective.
Those smart grid areas that fit within the traditional electricity utility business and policy model have a history of automation and advanced communication deployment to build upon.
Business and policy
The business cases, financial resources, paths to deployment, and models for enabling governmental policy are only now emerging with experimentation. This is true of the regulated and non-regulated aspects of the electric system.
High-tech culture change
A smart grid is socially transformational. As with the Internet or cell phone communications, our experience with electricity will change dramatically. To successfully integrate high levels of automation requires cultural change.
- Integrated Communications – High-speed, fully integrated, two-way communication technologies will make the modern grid a dynamic, interactive platform for real-time information and power exchange. An open architecture will create a plug-and-play environment that allows grid components to talk, listen and interact.
- Sensing and Measurement – These technologies will enhance power system measurements and detect and respond to problems. They evaluate the health of equipment and the integrity of the grid and support advanced protective relaying; they eliminate meter estimations and prevent energy theft. They enable consumer choice and demand response, and help relieve congestion.
- Advanced Components – Advanced components play an active role in determining the grid’s behavior. The next generation of devices will apply the latest research in materials, superconductivity, energy storage, power electronics, and microelectronics. This will produce higher power densities, greater reliability, and improved real-time diagnostics.
- Advanced Control Methods – New methods will be applied to monitor essential components, enabling rapid diagnosis and timely, appropriate response to any event. They will also support market pricing and enhance asset management.
- Improved Interfaces and Decision Support – In many situations, the time available for operators to make decisions has shortened to seconds. Thus, the modern grid will require wide, seamless, real-time use of applications and tools that enable grid operators and managers to make decisions quickly. Decision support with improved interfaces will amplify human decision making at all levels of the grid.
Objective of This Work
- To know about developing a two-way modernized electric network to replace the existing electric network to manage power so that brownout (A brownout is an intentional drop in voltage in an electrical power supply system used for load reduction in an emergency) which is actually caused by lack of peak capacity, not lack of energy can be resolved.
- To know about reliably integrating high levels of variable resources—wind, solar, ocean and some forms of hydro—into bulk power system.
- To know about driving carbon emissions reductions by facilitating renewable power generation, enabling electric vehicles as replacements for conventional vehicles, reducing energy use by customers and reducing energy losses within the grid.
- To know about demand reductions, savings in overall system, reserve margin costs, line loss reduction or improved asset management, lower maintenance and servicing costs (e.g. reduced manual inspection of meters) and reduced grid losses, and new customer service offerings.
- To know about safe work environments by reducing time on the road for meter reading, alerting workers of islanding and allowing for some grid repairs to be performed.
- To know about promote off peak usage, ensuring cyber security, feed-in tariffs (selling excess power back to the Grid) and demand response services to allow the utility to control usage in real time (for a discount or other benefits) to better manage load.
Introduction to the Thesis
The electric power industry needs to be transformed in order to cope with the needs of modern digital society. Customers demand higher energy quality, reliability, and a wider choice of extra services. And at the same time they want prices to be lower. In principle, the Smart Grid is an upgrade of 20th century power grids, which generally “broadcast” power from a few central generation nodes to a large number of users. Smart Grid will instead be capable of routing power in more optimal ways to respond to a wide range of conditions and to charge a premium to those that use energy during peak hours.
By 2020, more than 30 mega-cities will emerge on the Earth. Increased population together with a growing energy-dependence trend will require new technologies that are able to cope with a larger amount of energy resources. A rough estimation shows that by 2050, the world’s electricity supply will need to triple in order to keep up with the growing demand. That will require nearly 10000 GW of new generation capacity.
Climate change is now more real than ever. The era of fossil fuels will soon come to its end. And our nation is pretty much dependent on finite natural resources for energy generation. We are living in times when significant changes need to be made in the utility industry.
In the next coming years, the industry will not only experience advanced metering infrastructure deployment, but also new improved grid technologies. These new technologies will greatly expand the scale of benefits to both customers and utility.
But despite the changing environment; there are still some challenges that prevent utilities from rapid development of the smart grid concept. Decision makers and investors are still skeptical about the benefits of smart grid technologies. Therefore, it is important to present all these benefits in a clear and understandable way.
Improved grid reliability and power quality rules gain more and more attention as more regulators think about applying penalty-reward system against performance. Customer satisfaction rating should also be considered. Introduction of new telecommunication technologies with encryption and remote inspection of assets will increase the security of a grid and strengthen it.
Smart grid will bring a customer the ability to control energy consumption, using demand response. Such factors as peak shifting and overall conservation will impact a demand response system.
Prospects of Smart Grid Technologies for a Sustainable and Secure Power Supply
The vision and enhancement strategy for the future electricity networks is depicted in the program for “Smart Grids”, which was developed within the European Technology Platform (ETP) of the EU in its preparation of 7th Frame Work Program. Features of a future “Smart Grid” such as this can be outlined as follows:
- Flexible: fulfilling customers’ needs whilst responding to the changes and challenges ahead.
- Accessible: granting connection access to all network users, particularly for RES and high efficiency local generation with zero or low carbon emissions.
- Reliable: assuring and improving security and quality of supply.
- Economic: providing best value through innovation, efficient energy management and ‘level playing field’ competition and regulation.
It is worthwhile mentioning that the Smart Grid vision is in the same way applicable to the system developments in other regions of the world. Smart Grids will help achieve a sustainable development. Links will be strengthened across Europe and with other countries where different but complementary renewable resources are to be found. For the interconnections, innovative solutions to avoid congestion and to improve stability will be essential. HVDC (High Voltage Direct Current) provides the necessary features to avoid technical problems in the power systems. It also increases the transmission capacity and system stability very efficiently and helps prevent cascading disturbances. HVDC can also be applied as a hybrid AC-DC solution in synchronous AC systems either as a Back to-Back for grid power flow control (elimination of congestion and loop flows) or as a long-distance point-to-point transmission.
An increasingly liberalized market will encourage trading opportunities to be identified and developed. Smart Grids is a necessary response to the environmental, social and political demands placed on energy supply.
In what follows, the global trends in power markets and the prospects of system developments are depicted, and the outlook for Smart Grid technologies for environmental sustainability and system security is given.
Global Trends in Power Markets
In the nearest future we will have to face two mega-trends. One of them is the demographic change. The population development in the world runs asymmetrically. On the one hand, a dramatic growth of population is to be seen in developing and emerging countries. On the other hand, the population in highly developed countries is stagnating. Despite these differences, the expectancy of life increases everywhere.
This increase in population (the number of elderly people in particular) poses great challenges to the worldwide infrastructure. Water, power supply, health service, mobility – these are only some of the notions which cross one’s mind directly. The second mega-trend to be mentioned is the urbanization with its dramatic growth worldwide. In less than two years more people will be living in cities than in the country. Megacities keep on growing. Already today they are the driving force of the world’s economy: Tokyo e.g. is the largest city in the world, its population is 35 m people and it is responsible for over 40 % of the Japanese economic performance. Another example is Los Angeles with its 16 m citizens and a share of 11 % in the US-economy; or Paris with its 10 m citizens and 30 % of the French gross domestic product.
Both of these mega-trends make the demand for worldwide infrastructure grow. Fig. 8.1 depicts the development of world population and power consumption up to 2020. The figure shows that particularly in developing and emerging countries the increase is lopsided.
This development goes hand in hand with a continuous reduction in non-renewable energy resources. The resources of conventional as well as non-conventional oil are gradually coming to an end. Other energy sources are also running short. So, the challenge is as follows: for the needs of a dramatically growing world population with the simultaneous reduction in fossil power sources, a proper way must be found to provide reliable and clean power. This must be done in the most economical way, for a lot of economies, in the emerging regions in particular, cannot afford expensive environmentally compatible technologies.
Sources: IEA, UN, Siemens PG GS4 – 2010
Sources: IEA, UN, Siemens PG GS4 – 2010
Consequently, we have to deal with an area of conflicts between reliability of supply, environmental sustainability as well as economic efficiency. The combination of these three tasks can be solved with the help of ideas, intelligent solutions as well as innovative technologies, which is the today’s and tomorrow’s challenge for the planning engineers worldwide.
This is exactly what Siemens has been doing over the last 160 years. In the field of power supply, the founder of the company, Werner von Siemens, launched the electrical engineering with his invention of the dynamo-electric principle in 1866. Since that time electric power supply has established itself on all the continents, however, with an unequal degree of distribution. Depending on the degree of development and power consumption, different regions have very different system requirements.
In developing countries, the main task is to provide local power supply, e.g. by means of developing small isolated networks.
Emerging countries have a dramatic growth of power demand. Enormous amounts of power must be transmitted to large industrial regions, partly over long distances, that is, from large hydro power plants upcountry to coastal regions which involves high investments. The demand for power is growing as well. Higher voltage levels are needed, as well as long-distance transmission by means of FACTS and HVDC.
During the transition, the newly industrialized countries need energy automation, life-time extension of the system components, such as transformers and substations. Higher investments in distribution systems are essential as well. Decentralized power supplies, e.g. wind farms, are coming up.
Industrialized countries in their turn have to struggle against transmission bottlenecks, caused, among other factors, by increase in power trading. At the same time, the demand for a high reliability of power supply, high power quality and, last but not least, clean energy increase in these countries. In spite of all the different requirements one challenge remains the same for all: sustainability of power supply must be provided. Our resources on the Earth are limited, as shown in Fig.8.2, and the global climate is very sensitive to environmental influences. The global industrialization with its ongoing CO2 production is causing dramatic changes in the climate developments.
Sources: Wikipedia, Siemens PTD TI, 2010
There is no ready-made solution to this problem. The situation in different countries and regions is too complex. An appropriate approach is, however, obvious: power generation, transmission, distribution and consumption must be organized efficiently. The approach of the EU’s “Smart Grid” vision is an important step in the direction of environmental sustainability of power supply, and new transmission technologies can effectively help reduce losses and CO2 emissions.
Prospects of Power System Development
The development of electric power supply began more than one hundred years ago. Residential areas and neighboring establishments were at first supplied with DC via short lines. At the end of the 19th century, AC transmission was introduced, using higher voltages to transmit power from remote power stations to the consumers.
In Europe, 400 kV became the highest voltage level, in Far-East countries mostly 550 kV, and in America 550 kV and 765 kV. The 1150 kV voltage level was anticipated in some countries in the past, and some test lines have already been built. Fig. 8.5 and 8.6 depict these developments and prospects.
Due to an increased demand for energy and the construction of new generation plants, first built close and then at remote locations from the load centers, the size and complexity of power systems all over the world have grown. Power systems have been extended by applying interconnections to the neighboring systems in order to achieve technical and economic advantages. Large systems covering parts of or even whole continents, came into existence, to gain well known advantages, e.g. the possibility to use larger and more economical power plants, reduction of reserve capacity in the systems, utilization of the most efficient energy resources, as well as achieving an increase in system reliability.
In the future of liberalized power markets, the following advantages will become even more important: pooling large power generation stations, sharing spinning reserve and using most economic energy resources, and considering ecological constraints, such as the use of large nuclear and hydro power stations at suitable locations, solar energy from desert areas and embedding big offshore wind farms.
Examples of large AC interconnections are systems in North America, Brazil, China and India, as well as in Europe (UCTE – installed capacity 530 GW) and Russia (IPS/UPS – 315 GW), which are planned to be interconnected in the future.
It is, however, a crucial issue that with an increasing size of the interconnected systems the advantages diminish. There are both technical and economical limitations in the interconnection if the energy has to be transmitted over extremely long distances through the interconnected synchronous AC systems. These limitations are related to problems with low frequency inter-area oscillations voltage quality and load flow. This is, for example, the case in the UCTE system, where the 400 kV voltage level is in fact too low for large cross-border and inter-area power exchange. Bottlenecks are already spotted and, for an increase in power transfer, advanced solutions must be applied.
In deregulated markets, the loading of existing power systems will further increase, leading to bottlenecks and reliability problems. System enhancement will be essential to balance the load flow and to get more power out of the existing grid. Large blackouts in America and Europe confirmed clearly that the favorable close electrical coupling of the neighboring systems might also include the risk of uncontrollable cascading effects in large and heavily loaded synchronous AC systems.
Security of Supply – Lessons Learned From the Blackouts
The Québec’s system in Canada was not affected due to its DC interconnections to the US, whereas Ontario (synchronous interconnection) was fully “joining” the cascade. The reasons why Québec “survived” the Blackout are very clear:
- Québec´s major Interconnections to the affected Areas are DC Links.
- These DC-Links are like a Firewall against Cascading Events.
- They split the System at the right Point on the right Time, whenever required.
- Therefore, Québec was “saved”.
- Furthermore, the DCs assisted the US-System Restoration by means of “Power Injection”.
It can be seen that load flow in the system is not well matching the design criteria, ref. to the “hot lines”, shown in red color. In the upper right-hand corner of the figure, one of the later Blackout events with “giant” loop flows are attached which occurred just in the same area under investigation one year before. Fig. 8.8 shows that the probability of large Blackouts is much higher than calculated by mathematical modeling, particularly when the related amount of power outage is very large. The reasons for this result are indicated in the figure. This means that, when once the cascading sequence is started, it is mostly difficult or even impossible to stop it, unless the direct causes are eliminated by means of investments into the grid and by an enhanced training of the system operators for better handling of the emergency situations.
For these reasons, further Blackouts occurred in the same year. The largest was the Italian Blackout, six weeks after the US-Canada events. It was initiated by a line trip in Switzerland. Reconnection of the line after the fault was not possible due to a very large phase angle difference (about 60 degrees, leading to blocking of the Synchronic-Check device). 20 min later a second line tripped, followed by a fast trip-sequence of all interconnecting lines to Italy due to overload. During this sequence, the frequency in Italy ramped down for 47.5 Hz within 2.5 min, and the whole country blacked-out.
Several reasons were reported: wrong actions of the operators in Italy (insufficient load rejection) and a very high power import from the neighboring countries in general. Indeed, during the night from Saturday to Sunday, the scheduled power import was 6.4 GW – this is 24 % of the total consumption at that time (27 GW; EURELECTRIC Task Force Final Report 06-2004). The real power import was even higher (6.7 GW; possibly due to the country-wide celebration of what is known as “White night”.
In Table 1, a summary of the root causes for the Italian Blackout is given. It can be concluded, that the existing power systems from their topology are not designed for wide-area energy trading. The grids are close to their limits. Restructuring will be essential, and the grids must achieve “Smart” features, as stated before. This is also confirmed by the recent large blackout on 4.11.2006 which affected eight EU countries it has highlighted the fact that Continental Europe is already behaving in some respects as a single power system, but with a network not designed accordingly. Europe’s power system (including its network infrastructure) has to be planned, built and operated for the consumers it will serve. Identifying, planning and building this infrastructure in liberalized markets is an ongoing process that requires regular monitoring and coordination between market actors.
The electric power supply is essential for life of a society, like the blood in the body. Without power supply there are devastating consequences for daily life: breakdown of public transportation systems, traffic jams, computer outages as well as standstill in factories, shopping malls, hospitals etc.
Table 1 Summary of Root Causes for the Italian Blackout and Action Plan
UCTE Interim Report 10-27-2003
Use of Smart Grid Technologies for System Enhancement and Grid Interconnection
In the second half of the last century, high power HVDC transmission technology was introduced, offering new dimensions for long distance transmission. This development started with the transmission of power in a range of a few hundred MW and was continuously increased. Transmission ratings of GW over large distances with only one bipolar DC line are state-of-the-art in many grids today. World’s first 800 kV DC project in China has a transmission rating of 5 GW and further projects with 6 GW or even higher are at the planning stage. In general, for transmission distances above 700 km, DC transmission is more economical than AC transmission (≥ 1000 MW).
Power transmission of up to 600 – 800 MW over distances of about 300 km has already been achieved with submarine cables, and cable transmission lengths of up to about 1,000 km are at the planning stage. Due to these developments, HVDC became a mature and reliable technology. During the development of HVDC, different kinds of applications were carried out. They are shown schematically in Fig. 8.10. The first commercial applications were HVDC sea cable transmissions, because AC cable transmission over more than 80-120 km is technically not feasible due to reactive power limitations. Then, long distance HVDC transmissions with overhead lines were built as they are more economical than transmissions with AC lines. To interconnect systems operating at different frequencies, Back-to-Back (B2B) schemes were applied. B2B converters can also be connected to long AC lines a further application of HVDC transmission which is very important for the future is its integration into the complex interconnected AC system the reasons for these hybrid solutions are basically lower transmission costs as well as the possibility of bypassing heavily loaded AC systems.
Typical configurations of HVDC are depicted. The major benefit of the HVDC, both B2B and LDT, is its incorporated ability of fault-current blocking which serves as an automatic firewall for Blackout prevention in case of cascading events, which is not possible with synchronous AC links.
a) Back-to-Back Solution
b) HVDC Long Distance Transmission
c) Integration of HVDC into the AC System Hybrid Solution
Figure 8.10 Types of HVDC Transmissions
HVDC PLUS is the preferred technology for interconnection of islanded grids to the power system, such as off-shore wind farms. This technology provides the “Black-Start” feature by means of self-commutated voltage-sourced converters (VSC). Voltage-sourced converters do not need a “driving” system voltage; they can build up a 3-phase AC voltage via the DC voltage at the cable end, supplied from the converter at the main grid. Siemens uses an innovative Modular Multilevel Converter (MMC) technology for HVDC PLUS with low switching frequencies. Therefore only small or even nor filters are required at the AC side of the converter transformers. Fig. 8.12 summarizes the advantages in a comprehensive way. The specific features of MMC are explained in details in.
Since the 1960s, Flexible AC Transmission Systems have been developed to a mature technology with high power ratings. The technology, proven in various applications, became mature and highly reliable. FACTS, based on power electronics, have been developed to improve the performance of weak AC Systems and to make long distance AC transmission feasible. FACTS can also help solve technical problems in the interconnected power systems. FACTS are applicable in parallel connection (SVC, Static VAR Compensator – STATCOM, Static Synchronous Compensator), in series connection (FSC, Fixed Series Compensation – TCSC/TPSC, Thyristor Controlled/Protected Series Compensation – S³C, Solid-State Series Compensator), or in combination of both (UPFC, Unified Power Flow Controller – CSC, Convertible Static Compensator) to control load flow and to improve dynamic conditions. Fig. 8.14 show the basic configurations of FACTS.
GPFC is a special DC back-to-back link, which is designed for fast power and voltage control at both terminals. In this manner, GPFC is a “FACTS B2B”, which is less complex and less expensive than the UPFC. Rating of SVCs can go up to 800 MVAr, series FACTS devices are installed on 550 and 735 kV levels to increase the line transmission capacity up to several GW. Recent developments are the TPSC (Thyristor Protected Series Compensation) and the Short-Circuit Current Limiter (SCCL), both innovative solutions using special high power thyristor technology. The world’s biggest FACTS project with Series Compensation (TCSC/FSC) is at Purnea and Gorakhpur in India with a total rating of 1.7 GVAr.
Bulk Power UHV AC and DC transmission schemes over distances of more than 2000 km are currently under planning for the connection of various large hydropower stations in China Ultra high DC (up to 800 kV) and ultra-high AC (1000 kV) are the preferred voltage levels for these applications to keep the transmission losses as low as possible.
In India, there are similar prospects for UHV DC as in China due to the large extension of the grid. India’s energy growth is about 8-9 % per annum, with an installed generation capacity of 124 GW in 2006 (92 GW peak load demand). The installed generation capacity is expected to increase to 333 GW by 2017.
Central and Southern systems via three bulk power corridors which will build up a redundant “backbone” for the whole grid. Each corridor is planned for about 20 GW transmission capacity which shall be implemented with both AC and DC transmission lines with ratings of 4 – 10 GW each (at +/-800_kV DC and 1000 kv). Therefore, each corridor will have a set-up with 2 – 3systems for redundancy reasons. With these ideas, China envisages a total amount of about 900 GW installed generation capacity by 2020. For comparison, UCTE and IPS/UPS together sum up to 850 GW today.
The benefits of hybrid power system interconnections as large as these are clear:
• Increase in transmission distance and reduction in losses – with UHV
• HVDC serves as stability booster and firewall against large blackouts
• Use of the most economical energy resources – far from load centers
• Sharing of loads and reserve capacity
• Renewable energy resources, e.g. large wind farms and solar fields can be integrated much more easily
However, with the 1000 kV AC lines there are also some stability constraints: if for example such an AC line of this kind with up to 10 GW transmission capacities are lost during faults, large inter-area oscillations might occur. For this reason, additional FACTS controllers for power oscillation damping and stability support are in discussion.
The idea of embedding huge amounts of wind energy in the German grid by using HVDC, FACTS and GIL (Gas Insulated Lines) is depicted. The goal is a significant CO2 reduction through the replacement of conventional energy sources by renewable energies, mainly offshore wind farms. Power output of wind generation can vary fast in a wide range, depending on the weather conditions. Therefore, a sufficiently large amount of controlling power from the network is required to substitute the positive or negative deviation of actual wind power in feed to the scheduled wind power amount. Fig. 8.14 shows a typical example of the conditions, as measured in 2003. Wind power in feed and the regional network load during a week of maximum load in the E.ON control area are plotted. The relation between consumption and supply in this control area is illustrated in the figure. In the northern areas of the German grid, the transmission capacity is already at its limits, especially during times with low load and high wind power generation.
An efficient alternative for the connection of offshore wind farms is the integration of HVDC long distance transmission links into the synchronous AC system as schematically.
Deregulation and privatization are posing new challenges on high voltage transmission systems. System elements are going to be loaded up to their thermal limits, and wide-area power trading with fast varying load patterns will lead to an increasing congestion.
Environmental constraints, such as energy saving, loss minimization and CO2 reduction, will play an increasingly important role. The loading of existing power systems will further increase, leading to bottlenecks and reliability problems. As a consequence of “lessons learned” from the large blackouts in 2003, advanced transmission technologies will be essential for the system developments, leading to Smart Grids with better controllability of the power flows.
HVDC and FACTS provide the necessary features to avoid technical problems in the power systems; they increase the transmission capacity and system stability very efficiently, and they assist in prevention of cascading disturbances. They effectively support the grid access of renewable energy resources and reduce the transmission losses by optimization of the power flows. Bulk power UHV AC and DC transmission will be applied in emerging countries such as India and China to serve their booming energy demands in an efficient way.
This thesis tries to define the smart grid concept and where it is going as the infrastructure. It does so by providing an outlook on the electricity market and its players, explaining the main smart grid drivers, applications, challenges and benefits. As a part of this enterprise, power engineers, for example, are investigating efficient and intelligent ways of energy distribution & load management; computer scientists are researching cyber security issues for reliable sharing of information across the grid, the signal community is looking into advancing instrumentation facilities for detailed grid monitoring; wind engineers are studying renewable energy integration while business administrators are reframing power system market policies to adapt to these new changes to the system; the IT systems control the smart grid to ensure seamless operational environment. Making a power system SMART require modeling, identification, estimation, robustness, optimal control and decision making over networks.
Future Suggestion of Smart Grid
While it is yet clear what the smart grid will become in the future, the great potential to save energy and costs to utilities and consumers alike make it an extremely important technology. However, one clear cut goal of the smart grid is to give consumers more control and interaction with their energy usage. With this newfound connection, utilities and consumers alike will know more about how energy is being used in their area, and most importantly give them the ability to do something about it. Similar to what email did for the internet, many believe that it may take something as small as an iPhone application to make the smart grid the next big technology sensation. The biggest barrier is, as usual, cost—for the utility companies to build the infrastructure, and then rely on consumers to make the right energy choices to make the investment worthwhile.18 Perhaps consumers need to get out there and make the commitment to show utility companies that we are serious about energy conservation and savings, both for the environment and our wallets!
The power grid of the future will be a more internet-like grid, with multi-directional flows of central and dispersed—distributed energy resources (DER)—generation sources. This will enable generation and load matching, that can further facilitate energy management or support local “islanding” micro grids. The Smart grid will also include multi-directional flows of information and communications via central and dispersed intelligence, enabling fully integrated network management through smart materials and power electronics. And increased two-way communications throughout a combination of large- and small-scale mesh-like system will help to engage end users through the availability of real-time information and participation technology.
This paper has dealt with the evolution of Smart Power Grid System. It is still in it nascent stage. The whole power community is busy now in understanding and developing smart power grid system which is no longer a theme of future. This introductory paper is a small but a very vital step towards achieving the ultimate goal of making a “National Grid” a reality.