Wind power production and forecasted power 

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... and money while maintaining desired comfort levels. The ENERsip platform will expand conventional AMR (Automatic Meter Reading) systems beyond the meter via in-house networks, in order to obtain information and to allow optimized consumption in energy-smart buildings. Wind energy has characteristics that differ from conventional energy sources. If the energy contribution of this production source is not a cause of concern, the power balance, and therefore the impact in the supply security, needs attention due to the intermittent and random character of this production option. Wind capacity is installed to generate energy with negligible CO 2 emissions, but its contribution to meet peak load growth requirements is limited. Wind power cannot fully replace the need for a variety of “capacity resources”, which are dispatchable generators that are available to be used when needed to meet peak load. Wind power must be considered an energy resource, but not a peak capacity resource, because only a small fraction of total wind capacity has a high probability of running consistently. Wind is used when it is available and if it has some capacity value for reliability operation planning purposes that should be viewed as a bonus [2]. The output of wind power is driven by environmental conditions outside the control of the generators or the system operators. Since the wind is determined by random meteorological processes it is inherently variable. Supply of power from wind turbines is stochastic in nature and the actual power is more or less proportional to the third power of the wind velocity. The wind output varies seasonally between summer and winter [3] and the variations are also present on shorter time scales, namely on hourly basis [4]. Several extreme ramp rates were recorded [5]. Beyond the variability, a lot of wind generation occurs in hours when energy use is low. The uncontrollable nature of wind makes it less valuable to system operators than dispatchable power. The variability and uncertainty of wind energy production require that power system operators take measures to manage its delivery, increasing the cost incurred to balance the system and maintain reliability [6]. Unlike conventional capacity, wind-generated electricity cannot be reliably dispatched or perfectly forecasted, and exhibits significant temporal variability. The intermittency of wind energy can be reduced by the use of grid integration and technical and geographic distribution of the generators. These techniques can be grouped as aggregation and distribution methods and have as aim the substantial reduction of the global wind power variations. Also the improved forecasting techniques can increase the predictability of the wind power production and therefore minimize the impact in the system. However, although those improvements bring benefits, several periods of low wind production and substantial variations will remain. Thus, tools to respond to short- to medium-term and long-term variability will be needed, managing the operational and capacity reserve, respectively. For large scale integration of wind power the provision of flexible capacity reserve will be of crucial importance. To achieve that aim several options are possible [7]: • Power plants providing operational and capacity reserve; • Interconnection with other grid systems; • Curtailment of intermittent generation; • Distributed generation; • Complementarily between renewable sources; • Energy storage. All the above options have as aim the influence and control of the supply. However, to minimize the intermittence impacts, also the demand can be influenced, having a major role in the intermittence compensation, using demand-side management and demand-side response technologies. As far as security of supply is concerned, the most severe problems due to the wind power intermittence occur in the peak load hours. With higher energy consumption, the largest part of the available system resources to deal with the intermittence is already used and a sudden reduction of the wind power production can have critical consequences on the system reliability. Even in situations where the wind power variation is not high but the wind power production is low, if the wind power has a high share in the total installed power, the system may not have enough resources to face a lengthy absence of wind power. In both situations, notwithstanding the system reliability, the simultaneous occurrence of a higher consumption and a low wind power production will lead to higher operating costs. Due to the higher peak load and wind availability, the sudden reductions of the wind power production can be more severe in winter days. However, the probability of a large period of time with low wind availability is larger in the summer months, when the hot days without wind are usual. Due to the increasing installed capacity of air conditioners, the peak power consumption in the summer days is growing fast. Figure 1 shows a summer day in Portugal (July 21, 2008) with very low wind power production, during all the day. On such a day the energy consumption was high. On hot days the wind power production varies almost inversely relatively to the average temperature (Figure 2), whereas the energy consumption varies almost directly with the temperature (Figure 3). Such situation will lead to reliability problems in the systems with high wind power penetration. Thus, instead of acting in the supply side, to avoid the most severe intermittent situations, the demand-side must be influenced in the direction of achieve consumption reductions. Rather than attempting to match power generation to consumer demand, the philosophy of load management takes action to vary the load to match the power available. Through the proper application of demand-side management technologies it is possible to reduce the consumption to match the reductions of the wind power production and increasing the reliability [8]. As defined by EIA, DSM is "the planning, implementation, and monitoring of utility activities designed to encourage consumers to modify patterns of electricity usage, including the timing and level of electricity demand. It refers to only energy and load-shape modifying activities that are undertaken in response to utility-administered programs. It does not refer to energy and load-shaped changes arising from the normal operation of the marketplace or from government-mandated energy-efficiency standards. Demand-Side Management covers the complete range of load-shape objectives, including strategic conservation and load management, as well as strategic load growth." [10]. Generically, as far as security of supply is concerned any consumption reduction will contribute to mitigate the intermittence. With lower energy consumption, the installed power in renewable intermittent resources needed to meet the minimum renewable targets, will be lower. Additionally, the most severe intermittence problems occurs during the peak load hours and thus the DSM measures with greater impact in such hours are of large importance. However, in cases of high wind power penetration, the energy consumption reduction during the peak hours may not be enough, because due to the big production variations, such impact in the long term will not solve the supply-demand balance. In such situations it will be very important to have Demand Response technologies to “force” consumption reductions at near real time, in the precise moment in which the critical situations occur. With the DR technologies it is possible to direct or indirectly force a consumption reduction in critical situations, in a short time [9]. In the past, the electric system has been planned and operated under the supposition that the supply system must meet all customers energy use, and that is not possible to control the demand. However that supposition is starting to change due to the creation of opportunities for customers to manage their energy use in response to signals (prices or load contracts). The idea behind DR is that if the marginal peak load price is higher than the value that a consumer gets out of the services derived from the electricity, he would be willing to modify the demand, if paid the peak price or slightly less instead. A grid operator can obtain an economic benefit paying to a customer to reduce the consumption instead to paying a power producer to supply more output, because in peak periods, the production cost can be very high. Traditionally the DR technologies were typically used to attend to economical concerns. However, nowadays they can be used to improve the system reliability, reducing instantaneously the energy consumption to prevent the most unbalanced situations, like the problems that result from the large space conditioning consumption on days with reduced wind velocity. As more customers practice automated price-responsive demand or automatically receive and respond to directions to increase or decrease their electricity use, system loads will be able to respond to, or manage, variability from wind power production. Taking as reference the electric energy consumption in Portugal, in the year of 2008, an evaluation of the consumption evolution was made, considering a business- as-usual scenario (BAU) and a scenario with DSM measures application. In such evaluation, a consumption increase of 3%/year to the BAU scenario (average forecasted growth) and the application of DSM measures corresponding to 1% of the year consumption to the DSM scenario (2006/32/EC European Commission Directive on energy end-use efficiency) were considered (Figure 4). The application of demand-side management measures in Portugal with a consumption reduction of 1% by year can represent, in 2020, a consumption reduction of 10.3% relatively to the BAU scenario. For a renewable share, for instance of 50% of the generated energy, the DSM can reduce the needs of renewable power in ...