The ongoing liberalization process in Europe together with the growing penetration of renewable energy sources (RES), e.g. wind power, require an internationally oriented transmission planning approach that considers the increased uncertainties in terms of trade, location of generation and output of intermittent RES. This paper identifies and ranks bottlenecks, which is the first step of the transmission expansion planning process of interconnected transmission grids. A round-the-year approach is adopted by combining market simulations with static security analysis. Many combinations of load and generation (including renewables) are created and analyzed, using unit dispatch based on cost optimization. For each combination the branch loadings are determined for normal and contingency situations. A statistical risk-based approach for ranking the most severe bottlenecks is developed. The method is illustrated on a modified New England test system where wind power was added at several buses. A regional analysis and a detailed per-area analysis are presented.@en

Abstract In this study, a commercially available unit commitment and economic dispatch (UC-ED) tool is extended for the simulation of wind power integration in an international environment. An existing generation unit database for the Netherlands is extended to include conventional generation portfolios of neighbouring areas to the Netherlands. Furthermore, wind power in Germany is modelled such that the spatial correlation between wind speeds at different locations in the Netherlands and Germany is maintained. These additions allow the assessment of the benefits of international exchange for wind power integration and a comparison with other integration solutions. The UC-ED tool is applied for annual simulations of a power system with generation portfolios foreseen for the year 2014. Four variants for international exchange possibilities are investigated for different wind power penetrations. The opportunities of the following integration solutions are assessed: use of conventional generation in isolated systems, use of international markets, flexible combined heat and power (CHP), pumped hydro energy storage, compressed air energy storage and interconnection to a hydro-based system. The solutions are placed in an order of potential with respect to technical, economical and environmental aspects. The results show that the advantages of international exchange for wind power integration are large and provide an alternative for the development of energy storage facilities.@en

Abstract A production cost simulation model for the NorthWestern part of the UCTE system is developed in this paper. Information from various sources was gathered and combined to produce an integrated representative model of the areas under study. Specifically, the technical and economical limits of wind power integration within the power system are highlighted, by means of observing and analyzing various unit commitment schedules under different scenarios. The main question refers to which level of wind penetration the power system can operate in a safe and reliable fashion, while the incoming wind power is completely integrated and correlations between system variables in adjacent areas are taken into account. By answering this question, the system planner will have the flexibility to arrange in the future the power system operation accordingly so as to decrease the operation costs to a minimum and increase the efficiency of the total system to maximum. An investigation of this problem statement can only be executed with global models, which take into account both technical and economic constraints and further optimize the operation of the power system.@en

Abstract In this paper, we investigate the possibility of integrating 12 GW of onshore and offshore wind energy in the power system of the Netherlands. Interconnection capacities to the rest of the synchronous UCTE system and HVDC connections to Great Britain and Norway are modelled as flow gates, while sufficient transmission capacity for integrating wind is assumed to be present within the Dutch system itself. For this case study, we use realistic time series of aggregated 15-minute wind power production and forecast, based on one year of wind speed measurements and forecasts at various locations in the Netherlands and its coastal waters, and multi-turbine wind farm models. The technical capabilities of the foreseen conventional generation portfolios of the Netherlands and its neighbouring countries are modelled in detail, in terms of ramping abilities, fuel efficiency, and minimum up and down times. Particular attention is also paid to wind energy developments in Germany, since high correlations exist between the wind power outputs of the two countries. A preliminary evaluation in terms of margin at peak load, minimum load problems, and ability of conventional units to follow the load less wind variations is made, based on the net load duration curves of Netherlands and Germany in 2020. It is shown that smaller amounts of wasted wind (i.e. wind energy that cannot be taken by the system) due to minimum load problems occur when exchanges of excess wind energy can be scheduled between the two countries close to the operation time. This shows the importance of having larger geographic areas and well-organized cross-border trading to facilitate larger amounts of integrated wind energy. However, wasted wind cannot be completely avoided due to correlations in low load - high wind situations between the two countries. These results are confirmed through detailed chronological simulations of one year of operation, using a unit commitment and economic dispatch tool specifically ada- pted to perform wind integration studies. The potential for demand-side management to allow for a better integration of wind power is briefly explored.@en

This paper presents the results of a simulation of system operation in the Netherlands in the presence of future large-scale wind energy production. The study is aimed at identifying bottlenecks in system planning and operation due to wind integration, in particular base-load and ramp rate problems. These may constraint the amount of wind that can be accommodated given a projected production park of dispatchable units and yearly load profile by 2012. Wind data from 2004-2005, interpolated to existing locations for onshore and planned locations for offshore wind parks, were used to create a realistic yearly wind energy output profile. The unit commitment and economic dispatch formulation includes ramp rate constraints for generation schedules and reserve activation as well as minimum up- and down times. Of particular interest in this study are the combined heat & power (CHP) units, which impose additional constraints coupling their heat and energy production. Since no insight was available into the aggregated predictability of wind generation, both a 0-MW prediction, where conventional units are scheduled to meet the total load, and a perfect prediction have been investigated. No forms of electrical or heat storage were considered. The results show no ramp rate problems in the Dutch system by 2012, however base-load problems may arise at high wind penetration levels, only to be prevented by wasting available wind resources.@en