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Abstract
The vision and enhancement strategy for the future electricity networks is depicted in the program ”Smart Grids” which was developed within the European technology platform (ETP) of the EU in its preparation of7th frame work program. The features of a future ”Smart Grid” are flexible, accessible, reliable and economic. It is worthwhile mention that the smart grid vision is in the same way applicable to the system developments in the other ~egions of the world so it will help achieve a sustainable development. Links will be strengthened across all over the world where different but complementary renewable resources are to be found so for the interconnections, innovative solutions to avoid congestion and to improve stability will be essential; like High Voltage Direct Current (HVDC), Flexible AC Transmission Systems (FACTS), and Static V AR Compensation (SVC) which provide the necessary features to avoid technical problems in the power systems. An increasingly liberalized market will encourage trading opportunities to be identified and developed so smart grid is a necessary response to the environmental, social and political demands placed on energy supply.
Power systems planning, operation and control are usually affected by their stability and power quality traditionally this stability has concerned synchronous machines rotors motion in synchronism during and after small and large system disturbances. Recently, the stability of loads has been paid the same importance and attention as it has been found inter-related to voltage stability. Both of them affected and are effected by the other so power system stability have recently classified to the known synchronous angle stability and voltage stability.
Voltage stability concerns stable loads operation and acceptable voltage levels all over the network nodes. Its instability has been classified into steady-state and transient voltage instability according to the time spectrum of occurrence of the phenomena
Voltage instability has been observed in several forms which were reached to complete blackout of power systems in several countries. In the future the power quality problem and stability will have direct access to other interests such as power system security, reliability, planning control methods and power system harmonics suppression. The excessive use of power electronic devices will augment the chances of occurrence of the phenomena. Electronic static V AR compensators, flexible AC transmission systems (FACTS) and high voltage direct current systems (HVCDS) will be widely used to counteract the effect of such devices and to improve the voltage stability situation of large power systems. So power quality problem is a recent subject appeared with complication of power system which may be defined as any problem manifested in voltage, current or frequency deviations that results in failure or maloperation of customer equipments so both utilities and end users are concerned about the quality of electric power for the following reasons.
i.Modem load equipments are more sensitive to power quality than the old ones such as electronic and power electronic devices.
ii. The continued growth in modem control devices such as adjustable speed drives and computer-controlled systems has results in increasing harmonics level in power systems.
iii. Many things are now interconnected in the power network hence the fai
any component or part of the system has mush more important conseque
Since the power supply system can only control the quality of the voltage, and then standards in power quality are devoted to maintaining the supply voltage within ce limits.
Energy needs and increased infrastructure investment were long discussed before t August 2003 Blackout laid them bare. Skyrocketing energy commodity prices have the desire for better energy infrastructure more acute among policymakers. However, the likelihood of new national limits on carbon emissions has complicate incentives and investment response. One way to meet the myriad competing requir has been a return to energy conservation through better building standards, the resuscitation of energy efficiency programs and a new enthusiasm for demand res
However traditional regulation and old technology on the nation’s electric grid puts a natural cap on the potential for these improvements. This has led policymakers to the deployment of a ”smart grid” to maximize conservation opportunities, facilitate integration of more desirable green and renewable energy resources.
However, ”efficiency”,”demand response”, and ”smart grids” represent the latest in infrastructure fashion ... even though there are hurdles ahead, and it may start a bit some, we anticipate that retooling the grid will be an enduring trend.
In this thesis we do not recite the litany of virtues associated with ”self healing digi networks” and the potential of the grid’s digitization generically. We are taking for that an updated grid would be a good thing that achieves a whole variety of econo societal benefits. What we investigate here is the regulatory environment that is p an obstacle and the changes and trends we see facilitating a modernization of the electric grids.
So in the smart grids we will try hardly to achieve the power quality and voltage by using this new technology with cooperated with the others technologies.