Reliability assessment of wind integration in operating and planning of generation systems
ABSTRACT The integration of large amount of wind generation will have significant impact on both long-term planning and real-time operation of power systems. The intermittent and energy-limited characteristics are important factors in wind generation integration modeling. In terms of probabilistic reliability, new wind generation interconnection cannot meet the adequacy requirement by itself as load increases. Addition of conventional capacity is needed to compensate the intermittency of wind generation. The same is also true in real time operation. Scheduling wind generation in real-time can result in the reduction of system security; hence the requirement of operating reserve may increase. Reliability assessment based on probabilistic method is used in this paper to evaluate the impacts of wind integration from different aspects of planning and operation of a power system. Different reliability models of wind generation are presented. The IEEE Reliability Test System (IEEE-RTS) system is used to demonstrate the developed wind modeling.
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ABSTRACT: Installed wind capacity and contributions of wind to demand supply have grown in Spain in the last decade significantly. Wind is supplying a growing rate of demand. In specific situations it has supplied over 50% of Spanish demand. This has implications on the operation of the energy system. Systems facing large wind integration have to cope with production variability and uncertain predictability of wind resources. Thus, it is necessary to adapt reserve requirements to changing system conditions. Today thermal and hydro plants provide the regulation reserves. In the future, alternative reserve sources may gain more importance. The response of demand may be a possible way to provide these reserves. In this article, reserve requirements in a system facing high wind integration will be assessed. Demand response is considered as further reserve source in the system of Gran Canaria, an island belonging to Spain. Introduction Reserves are necessary to keep the balance between generation and demand in the electric system all the time. They are needed for both directions to increase generation and to lower it. Principally up-and down-reserves are focussed on compensating differences between real and forecasted demand and possible line or generator outages for the case of up-reserve. Reserve capacity is provided historically by thermal and hydro generators. Especially for small imbalances automatic response is necessary and thus generators have to react immediately. In the case of thermal generators this means that generators have to be online already and must preserve a part of their capacity for reserve needs. Hydro plants offer the convenience of immediate reaction and practically no ramping constraints as thermal generators do. In very wet or very dry times hydro plants may have restrictions to be used for reserve. In Spain, different types of regulation reserves are distinguished depending on the response time and the time to be available after the activation. Primary, secondary and tertiary reserves are activated sequentially from the moment of reserve need until the programmable divergence management comes into action. As installed capacity of wind has more than doubled in the last six years in Spain, reserves are used increasingly to cope also with wind production uncertainty. More capacity is planned for this intermittent energy source. Wind forecasting methods are improving but can´t give certainty for wind production outcome. Thus, the reserve level will be affected as well in the future by wind. As the capacity of the conventional generation park will stagnate or even decrease given the high share of wind energy in the future energy mix, reserve potential from thermal generators will decrease as well. So, other ways to provide reserves have to be found.01/2010;