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donderdag 7 april 2011

The Smart Grid: Report (1)

This article is part of a series of article about the Smart Grid. It explains the concept of the Smart Grid, how it will evolve and what technologies can/will be used for it. The articles of this series make up a report that I have written for a course that I follow as a student. It is recommended to read this articles in the correct order, because else it will probably be not that easy to understand everything. If there are any comments, remark or such on this report, please do not hesitate to contact me or post it as a comment. 



Introduction
The electric power industry evolved from a series of discoveries during the 18th and 19th century. And then by 1880, Thomas Edison had developed a commercially viable light bulb, and pioneering power station were beginning to become online. In 1882, a few power stations were opened both is the UK and in the US. Another key inventions at that time was the discovery of the transformer, which could step up the voltage. Almost simultaneously, the steam turbine was invented, facilitating the conversion of thermal energy to electricity using steam as the working fluid. Early plants generated electricity using waterwheels in streams or hydropower in dammed rivers. Coal fired plants expanded the technology further by generating steam that could be converted into electricity using steam turbines.


By the end of the 19th century, power companies had started to meter electricity and charge for electrical services. The early power system configuration evolved from these beginnings – a central generation plant with wires that brought services to local customers. The varying customer demands created problems for the generators who tried to match the supply to the demand. This led to the installation of generating equipment of different sizes that could be brought on- and off-line, as well as units that could supplement the “base” power generation to meet “peak loads”.

In the early days of the industry, reliability of supply was shaky and outages were commonplace. As the industry grew, new power stations were added and redundancy was introduced to provide multiple feeds to major service areas. At that moment it seemed logical that this industry had to be a monopoly because of the complexity of interfaces between generation, transmission and distribution.

By 1930, most cities in the US and many in Europe had electrical transmission and distribution systems. Rural electrification followed. By mid-century, the advent of more sophisticated technologies that relied on electrical transmission frequencies for accurate performance made reliability of supply even more important. Utilities then developed sophisticated transmission and distribution networks to provide not only a high degree of reliability, but also precise control of frequency and phase of the electricity. The growth in the demand for electrical services continued at a very fast rate. This led to further development of the industry and to expand its generation and transmission/distribution capacity.

A major change came in 1978 in the US because of the deregulation of the energy market. Market economists had long claimed that monopolies result in higher prices than would be obtained in a free market situation. Though it was difficult to unbundle the utility infrastructure, the strategy was to allow the entry of new generators into a competitive power market. Deregulation also spread to the UK  and  many other countries in Europe. Deregulation of the energy market makes the operation of the transmission grid complex – especially since it was originally designed for generating nodes that were under control of the utility, not the free market.

Today’s industry is still in a transitional phase. Problems in deregulation are being faced, and changes are being put into place. Gaming an unethical practices are being uncovered and addressed, but there still is a continuing evolution as new technology brings new challenges. Real-time pricing is a new possibility that will encourage  consumers to use discretionary appliances when power demand is low and generators are willing to sell power at lower rates to shift load away from peak use periods. Smart appliances are being developed that will turn themselves on or off depending on the spot price of electricity. The control and information technology needed to support these new possibilities are still in a stage of evolution, but they promise to provide more efficient and cost-effective electrical services in the future. In general the concept of the Smart Grid, the subject of this report, consist out of the introducing of the new technologies in the infrastructure of the electric grid, the real-time pricing of electricity, the smart appliances. But there are also a few other elements that belong to the concept of the Smart Grid, by example the use of electric vehicles for the storage of electricity when power demand is low.


Smart Grid
Smart grid is described as an upgrade for the power grid. But what will it eventually be, the smart grid? Although there are already many different definition for the smart grid, here I will define it as “ a superimposed tele-information networks on the electricity network”. The smart grid is a flexible switchable system of bridges linking people with technology and natural systems.

The function of an electrical grid is not a single task performed by one company,  but it consists of many different tasks and it is performed using multiple networks and by multiple power generation companies with multiple operators employing at varying levels of communication and coordination, most of which is manually controlled. But smart grids will increase the connectivity, automation and coordination between these suppliers, consumers and networks that perform either long distance transmission or local distribution tasks.

The paradigm on the power grid is changing, because businesses and homes are beginning to generate more and more electricity by their self, this by using wind- and solar power. And this enables them to sell surplus energy  back to their utilities. So, many of the consumers are also become suppliers of electrical energy. Modernization is necessary to improve the efficiency of electricity consumption, real-time management of power flows on the grid and to provide bi-directional metering needed to financially compensate local producers for the electrical energy they produce. Although transmission networks are already controlled in real-time, many in the US and European countries are antiquated by world standards. And the controlling in real-time of the power grid is currently only superficial and doesn’t allow the operator to control the grid at a ‘deep’ level. All this makes it unable for the electrical grid to handle modern challenges, such as those proposed by the intermittent nature of alternative (or renewable) electricity generation.

A smart grid is an definition for a concept that covers an aggregate of modernization for both transmission and distribution grids. The modernizations are in line with series of goals, including the facilitation of greater competition between providers, enabling greater use of energy sources with a variable energy production, establishing the automation and monitoring capabilities needed for bulk transmission at cross continent distances, and enabling the use of market forces to drive energy conservation.

Many of the features of the smart grid will be very apparent for the consumers such as smart meters instead of conventional meters. The approach is to make it possible for energy suppliers to charge variable electricity prices so that these prices reflect the large differences in cost of generating during peak periods and off periods. Such capabilities allow load control switches to control large energy consuming devices so that they consume electricity when it is cheaper to produce the electricity.

This could save energy, reduce costs and increase reliability and transparency, but there is a point where attention is needed and that is of the risks inherent with executing massive information technology projects must be addressed. The smart grid is envisioned to overlay the current electrical grid with an information and net metering system, that includes smart meters. Smart grids are being promoted by many governments as a way of addressing energy independence, global warming and emergency resilience issues.

The concept of the smart grids’ two-way communication system between suppliers and consumers to control appliances is not new. There are systems implemented that are capable of doing this, using analogue technology. But because of the growth of a digital network for the internet, it is considered more practical to use digital technology for this job. The increased data transmission capacity has made it possible to apply sensing, measurement and control devices with two-way communications to electricity production, transmission, distribution and the consumption elements of the electrical grid. These devices would then communicate information about the condition of the grid to the different users of the system, operators and other automated devices. This makes it possible for the average consumer to dynamically respond to changes in the grid condition, instead only utilities and very large customers.

Electricity is called to be an energy carrier and so the energy cannot be stored as electricity, so if one wants to store electrical energy, the only possibility is to convert the electrical energy into another form of energy which then can be stored for later use. Every time energy is converted from one form into another, there are always some losses. And thus is electrical  energy is stored, there will always be an amount of energy that will be lost while storing it. Besides the energy losses, there is always an extra cost to store energy. And because of the energy losses and this extra cost, it is not always preferred to store electrical energy. It is much more profitable to immediately use the electrical energy at the (almost) the same moment it is generation. And so within the concept of the smart grid, a big element is the matching of the supply and demand of electrical energy on the power grid.  

A difference between the current electrical grid and the smart grid is the intelligent monitoring system. Currently, the grid monitors the system to keep track of all electricity flowing, but this isn’t done is very detailed. But the smart grid would do this is much more detail. The extra information that will be collected makes it possible for the grid operators and consumers to make more informed decisions. Currently the monitor system of the power grid is automated, but has limited capabilities, it can only gather information about the condition on the grid. To make decisions for the power grid and then control it, the system mostly relies on a human intervention for this.  The smart grid would expand these monitor systems so that it can, not only monitor, but also automatically control the power grid and so there is less need for human interventions.
When more and more renewable energy will be integrated in the electrical grid, the more need there will be for a more detailed monitoring system. This is because many of the renewable energy sources have a variable production of electricity. And it is very difficult or almost impossible for the operators of the grid to exactly predict the variations in the electricity production of those energy resources. And thus with real time monitoring it is possible to retrieve the required information about these renewable energy sources at any time. One of the tasks of the smart grid is to retrieve and bring this data to the operators, consumers and other smart devices that are connected to the grid.  

The more detailed monitoring of the electrical grid will then make it possible to introduce real-time pricing. The price of electricity will then depend on the electricity demand at that moment, which sources of the energy mix are producing electricity, and several other elements. But not only will the electricity price depend on the demand, but in greater sense on the actual cost of generation at that moment. The electricity price will vary along what kind on energy sources are generating electricity at that moment. In this way, the smart grid will allow to turn on smart appliances, such as washing machines or factory processes that can run arbitrary, when the power is least expensive. And on the other hand, at peak times when there tends to be a ‘shortage’  of electricity, the smart grid could turn off selected appliances to reduce the demand.

A widely overlooked fact about the smart grid is that it is not a substitute for a real grid, but only an upgrade or an enhancement. The construction of a larger and better infrastructure of high-voltage transmission lines for the efficient delivery of electric power is a prerequisite to the construction of an effective smart grid (1) & (2).

Geschreven door Emile Glorieux

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