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This paper proposes a hierarchical coordination mechanism for coordinating the economic dispatch of transmission system operator (TSO) and distribution system operator (DSO). The challenge of dispatching large-scale distributed energy resources (DERs) is addressed. The coordination problem of dispatching energy and reserve is formulated. Benders decomposition is the underlying mathematical foundation of the proposed hierarchical coordination mechanism. We define the generalized bid function to approximate the dispatch cost of distribution network by a series of affine functions. The generalized bid function is communicated from DSO to TSO. By using convex AC optimal power flow model, the convergence of hierarchical coordination is guaranteed. A grid computing structure in General Algebraic Modeling System (GAMS) to accelerate the computation is proposed. The generalized bid function is simulated for various test cases. We also demonstrate the effect of DERs on the voltage magnitude and phase angle. The numerical results show that the hierarchical coordination using the generalized bid function converges to very close results compared with the results of centralized dispatch. Hierarchical coordination is capable of managing various network congestion scenarios and power loads. The generalized bid function provides a unified format of communication between TSO and DSO. [ABSTRACT FROM AUTHOR]

Abstract: The paper analyses the issues for consideration listed in the stock taking document “New Energy Strategy for Europe 2011–2020” and explores the impact of their implementation on the use of renewable energy sources. The main objective of the paper is to introduce and provide a summary of the theoretical and methodological achievements required for an analysis of the implications of such an EU level strategy. It also provides a summary of the results of the analysis of the impacts of the Strategy on a specific field; namely, on the use of renewable energy sources. Contradictions inherent in the Strategy are discussed as well, and a proposal is put forward to aid the resolution of these contradictions. The paper also points out that the further development of the theoretical and methodological achievements may result in the creation of a simulation model, the application of which could effectively aid the process of strategic planning and the testing of strategies prior to approval. Finally, the paper discusses how an EU level and/or a global network of energy security centres could promote the development and implementation of an energy policy ensuring the appropriate utilization of renewable energy sources. [Copyright &y& Elsevier]

Abstract: This paper describes a method to characterize the fluctuating electricity generation of renewable energy sources (RESs) in a power system and compares the different parameters for California and Germany. Based on this method describing the fluctuation and residual load, the potential contribution of grid-connected vehicles to balancing generation from renewable energy sources is analyzed for a 2030 scenario using the agent-based simulation model PowerACE. The analysis reveals that integrating fluctuating RES is possible with less effort in California because of a higher correlation between RES generation and the load curve here. In addition, RES capacity factors are higher for California and therefore the ratio of installed capacity to peak load is lower. Germany, on the other hand, faces extreme residual load changes between periods with and without supply from RES. In both power system scenarios, grid-connected vehicles play an important role in reducing residual load fluctuation if smart charging is used. Uncontrolled charging or static time-of-use tariffs do not significantly improve the grid integration of RES. [Copyright &y& Elsevier]

Abstract: Due to their numerous advantages, combined cycle power plants (CCPPs) have become an important technology for power generation. The part played by CCPPs on the power generation market includes frequent start-up/shutdown operations which must be optimized by means of innovative strategies, such as model-based methods. The availability of dedicated languages and libraries for physical system modeling facilitates the implementation of accurate large-scale models. However, the efficient resolution of optimization problems based on such models requires powerful algorithms, which impose a series of constraints on the model formulation, in particular, that of the lack of discontinuity source. This paper presents a method to transform a CCPP physical model designed for simulation in an optimization-oriented model, which can be further used with efficient algorithms to improve start-up performances. The methodology is based on the reformulation of the plant initially represented with discontinuity sources into a smooth model, by using continuous approximations of the Heaviside function. The validation results demonstrate the model consistency and emphasize the fact that it is accurate enough to be used for optimization and control purposes. [Copyright &y& Elsevier]

Abstract: This paper analyses the integration of the balancing power markets in Northern Europe including the Nordic system, Germany and the Netherlands. Two cases of balancing market integration are analysed: the current state with individual balancing markets, and the full integration of these markets, where the day-ahead market and the balancing market are settled separately. First, the day-ahead market is modelled as a common market for the whole European continent, while a simultaneous reserve procurement modelling is done for the Northern Europe. Available transmission capacity is considered to be allocated implicitly for the exchange of balancing services based on a trade-off between day-ahead energy and balancing capacity exchange. Next, the balancing energy market is modelled as a real-time power dispatch on the basis of the day-ahead market clearing results and the simulated imbalances. Detailed results for two different weeks in winter and summer are presented. They illustrate the consequences of market integration between two synchronous areas on procured and activated reserve, generation dispatch and power flows. It is demonstrated that cost savings can be achieved due to the use of cheaper balancing resources and less activation of reserves caused by imbalance netting. Such savings are estimated for a whole year of operation, and amount to approximately 400M€per year. [Copyright &y& Elsevier]

Abstract: The aim of this study is to develop representative simulation building energy data sets and benchmark models for the Egyptian residential sector. This study reports the results of a recent field survey for residential apartment buildings in Egypt. Two building performance simulation models are created reflecting the average energy consumption characteristics of air-conditioned residential apartments in Alexandria, Cairo and Asyut. Aiming for future evaluation of the cost and energy affects of the new Egyptian energy standard this study established two detailed models describing the energy use profiles for air-conditioners, lighting, domestic hot water and appliances in respect to buildings layout and construction. Using EnergyPlus simulation tool the collected surveyed data was used as input for two building simulation models. The simulation models were verified against the apartment characteristic found in the survey. This paper presents details of the building models including the energy use patterns and profiles created for this study. [Copyright &y& Elsevier]

Abstract: This paper presents the analysis and comparison of the main active techniques for islanding detection used in grid-connected microinverters for power processing of renewable energy sources. These techniques can be classified into two classes: techniques introducing positive feedback in the control of the inverter and techniques based on harmonics injection. Accurate PSIMTM simulations have been carried out in order to perform a comparative analysis of the techniques under study and to establish their advantages and disadvantages according to IEEE standards. [ABSTRACT FROM AUTHOR]