Electricity is produced in power stations using turbines and generators. A turbine converts available energy into rotation while electric. Coordination of electricity transmission and generation investments. Hung-po Chaoa,⁎, Robert Wilsonb a Energy Trading Analytics, LLC, United States of. Note: An energy efficiency investment is defined as the incremental spending on new energy-efficient equipment or the full cost of refurbishments that. DAKAR RALLY 2014 LOPRAIS INSTAFOREX TeamViewer and skill and to be. I can install blocked. If theAdministrationadministratoradministrator domain for change90 days username, password, off - McAfee Enterprisemenus all connectionnecessery. The ad to save.
The first step in any power supply design is to determine the input current. The typical waveform for an alternating current is a sine wave see Figure 1. There are several indicators that must be taken into account when working with an AC power supply:. Alternating current AC is the way electric power is transmitted from generating facilities to end users. It is used for power transportation because electricity needs to be transformed several times during the transportation process.
Electric generators produce voltages of about 40,V, or 40kV. This voltage is then stepped up to anywhere between kV and kV, to reduce power losses when transporting electric current over long distances. Once it reaches its destination area, the voltage is stepped down to between 4kV and 35kV.
Finally, before the current reaches individual users, it is reduced to V or V, depending on the location. All these changes in voltage would be either complicated or very inefficient to do with direct current DC , because linear transformers depend on voltage fluctuation to transfer and transform electrical energy, so they can only work with alternating current AC. By using a transformer, the alternating current AC input voltage is reduced to a value more suitable for the intended application.
Then, the reduced AC voltage is rectified and turned into a direct current DC voltage, which is filtered in order to further improve the waveform quality Figure 2. Because the input voltage is transformed at the input, the necessary transformer would have to be very large and therefore very heavy.
At low frequencies e. This demands large transformer cores, which makes miniaturization of these power supplies practically impossible. These linear regulators dissipate any extra energy in the form of heat. For low power, does not pose much of a problem. However, for high power, the heat that a regulator would have to dissipate to maintain a constant output voltage is very high, and would require adding extremely large heatsinks.
Switching power supplies are now possible thanks to the evolution of semiconductor technology, especially thanks to the creation of high-power MOSFET transistors, which can switch on and off very quickly and efficiently, even if large voltages and currents are present.
In switching AC power supplies, the input voltage is no longer reduced; rather, it is rectified and filtered at the input. Then the DC voltage goes through a chopper, which converts the voltage into a high-frequency pulse train. Finally, the wave goes through another rectifier and filter, which converts it back to direct current DC and eliminates any remaining alternating current AC component that may be present before reaching the output see Figure 3. As could be expected, this new design method does have some drawbacks.
This creates a need for more complex control circuitry, which in turn adds complexity to the design. Nevertheless, these filters are made up of components that can be easily integrated, so it does not affect the size of the power supply significantly. An alternating current AC power supply can either be single-phase or three-phase:. The main difference between these two configurations is the ability to add a neutral wire see Figure 5. Delta connections offer greater reliability, but Y connections can supply two different voltages: phase voltage, which is the single-phase voltage supplied to homes, and line voltage, for powering larger loads.
Because a standard power distribution system must supply power to both three-phase and single-phase systems, most power distribution networks have three lines and a neutral. This way, both homes and industrial machinery can be supplied with the same transmission line. Therefore, the Y configuration is the most commonly used for power distribution, whereas the delta configuration is typically used to power three-phase loads, such as large electric motors.
The voltage at which the power grid delivers single-phase electric power to its users has various values, depending on the geographical location. Otherwise, you could damage the power supply or the device connected to it.
Table 2 compares the grid voltages in different areas around the world. In the western city of Osaka, electricity suppliers bought 60Hz generators from the United States, while in Tokyo, which is in the east of Japan, they bought 50Hz German generators. Both sides refused to change their frequency, and to this day Japan still has two frequencies: 50Hz in the east, 60Hz in the west.
As mentioned before, three-phase power is not only used for transportation, but is also used to power large loads, such as electric motors or charging large batteries. This is because the parallel application of power in three-phase systems can transfer much more energy to a load, and can do so more evenly, due to the overlapping of the three phases see Figure 6.
For example, when charging an electric vehicle EV , the amount of power you can transfer to the battery determines how fast it charges. These chargers, are limited in power by the grid and the AC socket. On the other hand, three-phase power supplies convert the power from AC to DC externally, and can transfer over kW to the battery, enabling super-fast charging.
Alternating current is used to transport electric power all across the electric grid, from generators to end users. An alternating current AC circuit can be configured as a single-phase or a three-phase system. Single-phase systems are simpler, and can deliver enough power to supply an entire house, but three-phase systems can deliver much more power in a more stable way, which is why they are frequently used to supply power for industrial applications.
By contrast, switching power supplies have become extremely popular, because they use switching regulators to convert AC to DC power. Did you find this interesting? Get valuable resources straight to your inbox - sent out once per month!
Session popupval Session textval Session Titefor popup. Produced and distributed at relatively low voltages--around volts--direct current electricity weakened substantially as it traversed the copper distribution lines. In practice, customers needed to be within one mile of a generating plant to receive power. As a result, the emerging paradigm of electric power production appeared to consist of cities being populated by numerous power plants, each selling to customers within a small radius.
Typically, the large investment required for the plant prohibited one company from owning all of them. But the firms often tried to win lucrative customers in the others' turfs. When Samuel Insull arrived in Chicago in , the town hosted more than twenty companies producing electricity. The British-born secretary of Thomas Edison, Insull assumed the presidency of the small Chicago Edison company, one of many Edison franchises around the country. Because of his work in Chicago, Insull is remembered for his many managerial and technological innovations that transformed the utility system into its modern structure.
Quickly learning at his new job, Insull realized that his company could make more money by increasing what became known as the "load factor"--the ratio of average daily or annual power use to the maximum load sustained during the same period. Since Insull needed to purchase equipment to meet the peak load of use during a day--typically in the evening when customers used electric lights--he was stuck with power generating technology that sat idle most of the rest of the day.
But Insull understood that if he could find customers who would use electricity during off-peak times, he could increase his company's income while avoiding new capital purchases though he would still incur marginal expenses related to increased fuel use. Those customers existed, though many generated power for themselves.
By enticing customers such as street railway companies, ice houses, and other businesses with low rates for off-peak power usage, Insull increased his load factor dramatically. He also found that lower-cost power stimulated demand, while still earning healthy profits for his company. Insull also realized how to exploit new technologies. For example, during the late s and s, a few power companies in Europe began using a steam turbine to power generators instead of reciprocating steam engines.
Large, bulky, noisy, and hard to maintain, the reciprocating engines of the day converted up-and-down motion to rotary motion for use by electric generators through the use of a large flywheel. But by the end of the 19th century, these behemoths were reaching limits to their productive capacity.
The new steam turbines, invented by Englishman Charles Parsons in , on the other hand, produced rotary motion directly, as steam passed through vanes on a long shaft. Much smaller in size, simpler mechanically, and more quiet than reciprocating engines, steam turbines produced a great amount of power from a small package.
More importantly, the turbines could be scaled up to produce even more power with proportionally less investment in material. In other words, the steam turbine exhibited great "economies of scale" such that larger units produced electricity at lower unit cost. Taking a great risk at the time, Insull ordered a turbine-generator set from the General Electric company in that produced 5, kilowatts kW of power 5 megawatts [MW]. Pleased with the unit's performance, he ordered other turbines that generated 12 MW in Power costs plummeted, allowing the company to sell more electricity at still lower rates.
Using steam turbines would not have been a successful strategy had it not been for Insull's use of an associated new technology--alternating current AC transformers. Developed in the s, AC transformers overcame the technical limitation of transmitting low-voltage direct-current to distances beyond one mile.
When power produced with already existing AC generators was transformed up to high voltages, current could flow for many miles without significant degradation. In , for example, Edison competitor Westinghouse Electric built a system of water-turbine generators at Niagara Falls that produced power for transmission to Buffalo, 20 miles away.
The AC power illuminated lights, just like direct current, and it powered the new AC motors that recently came to market. Since it could do everything direct current could do--with the important plus that it could be transmitted long distances--AC quickly won the day, leading to the demise of Edison's direct current systems. Insull quickly realized that competition in the electric power supply business would never allow him to exploit the scalable turbine-generators and AC transmission systems.
After all, if many companies divided the market for electricity, none would have the demand for power that could be met by the bigger turbine-generators. To remedy the problem, Insull sought to consolidate his company with others. After buying the firms, he often turned their generating stations into substations, relegating the generating equipment to back-up spares, and he used large, efficient steam-turbines to produce power for all customers.
He also sought new customers, even some rural customers outside the city limits, to help him diversify the company's usage patterns and increase the load factor. Successful in his efforts, Insull acquired 20 other utility companies by and renamed the firm "Commonwealth Edison. As a result, Insull's strategies became emulated by utility entrepreneurs in other cities throughout the United States.
As successful as Insull's company may have been, it was not universally loved. A virtual monopoly in Chicago, the company reminded many public-spirited politicians and individuals of other monopolies that rubbed people the wrong way, with railroads being the most notorious. Becoming the life blood of American commerce, the railroad industry by the s had become effective monopolies within their markets, after enduring a period of heated and destructive competition.
In several cases, railroad companies spent lavishly to lay down duplicate rail lines between lucrative markets and invested heavily in engines, cars, and other equipment, only to find that they could not make sufficient profits because of intense price competition. Eventually, railroad owners realized that merging operations with competitors allowed them to increase rates and make more money. Attempting to eliminate monopoly abuses of the railroad companies, several state legislatures and the federal Congress passed legislation for creation of bodies that would regulate rates.
Unfortunately for railroad customers, most of these regulatory bodies proved ineffectual. Regulation gained a more substantial foundation during a period of political agitation known as the Progressive era, which lasted from around through World War I. At the heart of regulation was the acceptance of the notion that some industries, such as the railroad business, constituted "natural monopolies. In the railroad business, the large investment in equipment meant that duplication of facilities would incur great waste of financial and material resources, thus leading to overall higher costs for companies and higher prices to customers.
Thus, monopoly appeared to be the natural outcome of such a situation, where one company could minimize the waste of resources to serve customers. In short, the railroad business was a "natural monopoly," one in which big technology and the high cost of investment led companies to move to a non-competitive environment.
The situation seemed similar to what was occurring in the electric utility business. As electric power firms consolidated with others to exploit the benefits of large-scale turbine-generators and alternating current transmission, they increasingly looked like the epitome of natural monopolies.
They were joined by other "public utilities," such as water and transportation industries that constituted, according to Richard T. Ely, an economist writing in , "monopolies because, we know from experience, we cannot have in their case effective and permanent competition. The big question for progressive reformers was how to gain for society the benefits of natural monopoly without suffering the abuses common among monopolist owners?
The answer actually took two forms--municipal ownership and state regulation of companies. By purchasing firms providing essential services and commodities, cities could ensure that the benefits of natural monopoly would flow directly to the people or so it was hoped.
In the electricity supply business, customers would enjoy lower rates as the city-owned utility exploited economies of scale and increased sales to greater numbers of people and businesses. Since cities have no stockholders demanding dividend payments or returns on investment, they could pass on savings directly to their citizens.
While municipalization of electric utilities enjoyed growing popularity, they did not win universal approval. Progressive reformers, for example, had been strident opponents of corrupt city governments. Why should political officials all of the sudden gain enlightened management skills when operating power systems when they so blatantly stole from the public coffers in so many other situations?
And in attempts to maintain low prices, for political reasons, managers might neglect maintenance, refrain from necessary investment in capital equipment, and offer low salaries that would discourage hiring of superior engineers and staff. Moreover, several critics of municipal systems viewed them as attempts to socialize American industry at a time when private enterprise still carried much popularity in society--the existence of abusive monopolies notwithstanding. As an alternative, many progressives looked to state regulation.
Though several states had created regulatory bodies to oversee the activities of railroad companies--with Massachusetts' railroad commission created in being one of the most notable--few had the power to enforce their recommendations nor could they establish rates and fares. But the new type of regulation, promoted by progressive Republican governors in Wisconsin and New York in the first few years of the 20th century, was different. In , for example, Wisconsin's Governor Robert La Follette pushed through creation of a railroad commission that had full jurisdiction over a railroad's rates, schedules, service, and operations of the state's transportation companies.
Two years later, in July , the Wisconsin legislature extended regulation to the state's electric companies. The commission used its powers to compel utilities to develop standard accounting techniques, and it had the right to investigate companies' books as part of the process for determining rates based on the physical valuation of a company's properties. Just a month earlier, New York governor Charles Evan Hughes, signed into law a similar measure to create a regulatory body for the Empire State.
Though the Wisconsin statute proved more sweeping in several respects, both states deservedly take credit for initiating the idea of state regulation of electric utilities. Gaining support from politicians and civic reform groups, state regulation of utilities became commonplace, such that by , 43 more states followed the example of New York and Wisconsin by establishing government oversight of electric utilities. Despite the move toward state regulation, the idea that city-owned utilities could better derive the benefits of natural monopolies for their citizens continued to hold some appeal.
In fact, the number of municipal utilities peaked in , with more than 2, "munis" in existence. The overall purpose of regulation, as viewed by its founders, was to serve as a body that would enforce the responsibilities and rights of electric power companies and their customers.
For example, utility companies were required to serve all customers without discrimination who sought to buy power. To fulfil this "obligation to serve," they would need to raise capital and build plants to meet projected loads.
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