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The new tendencies in the power system organization and the fast-changing technologies in the power industry dictate the need to keep track of the international experience and activities in the field of the modern economic dispatch problem. The goal of this paper was to provide a detailed account for papers published after 1990, the year that saw the beginning of major transformations in the power system organization. A comprehensive survey on mathematical formulations and a general background of methods, analyses, and developments in the field of economic dispatch is presented for the past 20 years based on more than 150 publications. The research literature in the field is classified into sections covering economic dispatch in both regulated and deregulated (reregulated) energy markets and where variable, partial predictable electricity generation is part of the generation portfolio. A database of the most common test systems used in the literature to test different economic dispatch methodologies is also provided.understanding of the problem and of the progress made to date, as well as for the electric utility industry to choose the most relevant solutions for their systems.The idea behind the ED problem is that at the central power control center the load changes are continuously monitored (in real time) and the dispatcher regulates generation (typically only real power is considered) to match the total power generation with the total power demand. This generation regulation is performed in such a manner as to minimize the operating cost while satisfying all the operating constraints. Such constraints may include the load balance, the transmission constraints, the spinning reserve of the system, multiple emission requirements, and minimum upper and lower limits [9][10][11][12]. Important aspects of this optimization problem are that the generation cost of each individual unit is not proportional to the generation level of the respective unit and that the power systems are geographically spread out, and thus, the transmission losses are dependent on the generation and demand patterns and their flow within the system.In deregulated energy markets, the vertically integrated utilities serving their own load are replaced by competing entities in a horizontally integrated environment. The GENCOs are no longer responsible for meeting the daily load cycle, which is now the system operator's (SO) responsibility, but the net sum of a set of transactions is the one that determines the shape of a GENCO's profile. Thus, from the view point of GENCOs, the ED problem may be formulated as a maximization of the profit [11][12][13] or as a minimization of the cost incorporating power wheeling costs [14,15]. Further to the classical formulation of the ED problem, reactive power dispatch may also be considered.According to the newly established regulations toward climate change in many European countries and in the USA [16,17], variable renewable energy sources (RES), such as wind and solar, is expected to increase its penetrati...

Many real-life optimization problems often face an increased rank of nonsmoothness (many local minima) which could prevent a search algorithm from moving toward the global solution. Evolution-based algorithms try to deal with this issue. The algorithm proposed in this paper is called GAAPI and is a hybridization between two optimization techniques: a special class of ant colony optimization for continuous domains entitled API and a genetic algorithm (GA). The algorithm adopts the downhill behavior of API (a key characteristic of optimization algorithms) and the good spreading in the solution space of the GA. A probabilistic approach and an empirical comparison study are presented to prove the convergence of the proposed method in solving different classes of complex global continuous optimization problems. Numerical results are reported and compared to the existing results in the literature to validate the feasibility and the effectiveness of the proposed method. The proposed algorithm is shown to be effective and efficient for most of the test functions.

Solid State Transformers (SST) may become, in the near future, key technological enablers for decentralized energy supply systems. They have the potential to unleash new technologies and operation strategies of microgrids and prosumers to move faster towards a low carbon-based economy. This work proposes a paradigm change in the hierarchically and distributed operated power systems where SSTs are used to asynchronously connect the many small low voltage (LV) distribution networks, such as clusters of prosumers or LV microgrids, to the bulk power system. The need for asynchronously coupled microgrids requires a design that allows the LV system to operate independently from the bulk grid and to rely on its own control systems. The purpose of this new approach is to achieve immune and resilient by design configurations that allow maximizing the integration of Local Renewable Energy Resources (L-RES). The paper analyses from the stability point of view, through simplified numerical simulations, the way in which SST-interconnected microgrids can become immune to disturbances that occur in the bulk power system and how sudden changes in the microgrid can damp out at the Point of Common Coupling (PCC), thus achieving better reliability and predictability in both systems and enabling strong and healthy distributed energy storage systems (DESSs). Moreover, it is shown that in a fully inverter-based microgrid there is no need for mechanical or synthetic inertia to stabilize the microgrid during power unbalances. This happens because the electrostatic energy stored in the capacitors connected behind the SST inverter can be used for a brief time interval, until automation is activated to address the power unbalance for a longer term.

Technological developments are pushing for new solutions based upon massive integration of renewable electricity generation in networks already facing many challenges. This paper presents a novel approach to managing the energy transfer towards prosumers making use of smart management of local energy storage. The proposed design (including storage dimensioning) is based on several operating scenarios in which the prosumer might operate as: (i) a "load only" entity (from a grid perspective), thus exhibiting investment resiliency against regulatory changes and high energy efficiency; or (ii) a prosumer, in case regulatory opportunistic profit might be available. This can be realized within a newly proposed Uni-directional Resilient Consumer (UniRCon) architecture. The major aim of the proposed architecture is to achieve optimal self-consumption while avoiding curtailment even in a changing regulatory environment like, for example, the total lack of incentives for generation based on renewable energy sources (RES). One of the major advantages of the proposed architecture consists in the adaptability to changes in the regulatory and market environment. The term resilience is used with multiple meanings: (a) the prosumer's financial resilience against regulatory changes when investment calculations assume no-grid injections; (b) the prosumer's technical resilience, with electrical design based on standalone operation; (c) the resilience of clusters of interconnected end-user installations with enabled community-level electricity exchange, independent of the existing main grid supply; (d) the contribution to grid resilience, by enabling AC microgrid (MG) operation in island mode when large portions of the grid are formed by clusters of UniRCon prosumers (the ease of islanding segmentation of the local grid in case of emergencies). For proof of concept, three use-cases are detailed: (i) photovoltaic (PV) installations connected behind the meter; (ii) PV and storage available and controllable behind the meter; and (iii) the UniRCon architecture. The three use-cases are then compared and assessed for four near-future timelines as starting points for the investment. Numerical simulations show the attractiveness of the UniRCon solution in what concerns both system operation costs and supply resilience. Savings are expressed as opportunity savings arising from difference in tariffs while charging and discharging the storage unit and due to the avoidance of curtailment, as well as special taxes for the connection of PV (depending on regulatory environment). An extension of the UniRCon concept is presented also at community scale, with neighbourhood energy exchange inside a resilient cluster.