Renewable Energy Sources are becoming widely spread, as they are sustainable and low-carbon emission. They are mostly penetrating the MV Distribution Networks as Distributed Generators, which has ...determined the evolution of the networks’ control and supervision systems, from almost a complete lack to becoming fully centralized. This paper proposes innovative voltage control architectures for the distribution networks, tailored for different development levels of the control and supervision systems encountered in real life: a Coordinated Control for networks with basic development, and an optimization-based Centralized Control for networks with fully articulated systems. The Centralized Control fits the requirements of the network: the challenging harmonization of the generator’s capability curves with the regulatory framework, and modelling of the discrete control of the On-Load Tap Changer transformer. A realistic network is used for tests and comparisons with the Local Strategy currently specified by regulations. The proposed Coordinated Control gives much better results with respect to the Local Strategy, in terms of loss minimization and voltage violations mitigation, and can be used for networks with poorly developed supervision and control systems, while Centralized Control proves the best solution, but can be applied only in fully supervised and controlled networks.
We address the problem of optimally re-routing the feeders of urban distribution network in Milano, Italy, which presents some peculiarities and significant design challenges. Milano has two separate ...medium-voltage (MV) distribution networks, previously operated by two different utilities, which grew up independently and incoordinately. This results in a system layout which is inefficient, redundant, and difficult to manage due to different operating procedures. The current utility UNARETI, which is in charge of the overall distribution system, aims at optimally integrating the two MV distribution networks and moving to a new specific layout that offers advantages from the perspectives of reliability and flexibility. We present a mixed-integer programming (MIP) approach for the design of a new network configuration satisfying the so-called 2-step ladder layout required by the planner. The model accounts for the main electrical constraints such as power flow equations, thermal limits of high-voltage (HV)/MV substation transformers, line thermal limits, and the maximum number of customers per feeder. Real power losses are taken into account via a quadratic formulation and a piecewise linear approximation. Computational tests on a small-scale system and on a part of the Milano distribution network are reported.
In this paper an optimization problem designed to calculate electric grid specific indicators to be used within model-based methodologies for the definition of alternative electricity market bidding ...zone configurations is designed. The approach integrates within the framework of a bidding zone review process aligned to the specifications of the Commission Regulation (EU) 2015/1222 (CACM) and Regulation (EU) 2019/943 of the European Parliament and of the Council (CEP). The calculated solution of the optimization provides locational marginal prices and allows to determine, outside the optimization problem, the power transfer distribution factors for critical elements. Both indicators can be used as inputs by specially designed clustering algorithms to identify model-based electricity market bidding zone configurations, as alternative to the current experience-based configurations. The novelty of the optimization problem studied in this paper consists in integrating the N-1 security criteria for transmission network operation in an explicit manner, rather than in a simplified and inaccurate manner, as encountered in the literature. The optimization problem is evaluated on a set of historical and significant operating scenarios of the Italian transmission network, carefully selected by the Italian transmission system operator. The results show the optimization problem capability to produce insightful results for supporting a bidding zone review process and its advantages with respect to simplified methodologies encountered in the literature.
With the development of distributed generation and demand-side response, traditional consumers are now converted into prosumers that can actively produce and consume electricity. Moreover, with the ...help of energy integration technique, prosumers are encouraged to form a multi-energy community (MEC), which can increase their social welfare through inside multi-energy sharing. This paper proposes a day-ahead cooperative trading mechanism in a MEC that depends on an energy hub (EH) to couple electricity, natural gas, and heat for all prosumers. The model of the traditional uncooperative local integrated energy system (ULIES) is also built as a comparison. A satisfaction-based profit distribution mechanism is set according to prosumers’ feelings about the extra cost they save or extra profit they gain in MEC compared with that in ULIES. Finally, case studies are set to analyze the utility of MEC in enlarging social welfare, after considering the effects of prosumers’ electricity usage patterns and buy-and-sell prices in retail market. The results of satisfaction-based profit distribution are also analyzed to verify that it can save the cost or increase the profit of each prosumer and EH.
The high penetration of Renewable Energy Sources into electric networks shows new perspectives for the network’s management: among others, exploiting them as resources for network’s security in ...emergency situations. The paper focuses on the frequency stability of a portion of the grid when it remains islanded following a major fault. It proposes an optimization algorithm that considers the frequency reaction of the relevant components and minimizes the total costs of their shedding. The algorithm predicts the final frequency of the island and the active power profiles of the remaining generators and demands. It is formulated as a Mixed-Integer Non-Linear Programming problem and the high computation time due to a large-size problem is mitigated through a simplified linear version of the model that filters the integer variables. The algorithm is designed to operate on-line and preventively compute the optimal shedding actions to be engaged when islanding occurs. The algorithm is validated for a typical distribution grid: the minimum amount of shedding actions is obtained while the most frequency reactive resources are maintained in operation to assure a feasible frequency. Finally, time-domain simulations show that the optimal solution corresponds to the one at the end of the network’s transients following the islanding.
Decentralized hybrid energy systems are promising long-lasting solutions to support socio-economic development in compliance with environmental concerns. Traditionally, microgrid planning has mainly ...focused on economics only, sometimes with reliability or environmental considerations, and the project costs have been estimated by approximating the multi-year operation of the system with a single-year approach, thus neglecting long-term phenomena. We propose a multi-objective multi-year method to plan microgrids in the Global South, accounting for socio-economic (Net Present Cost, job creation), security (public lighting coverage) and environmental impacts (carbon emissions, land use); the entire multi-year lifespan of the project is considered, including demand growth and assets degradation. The advanced version of the augmented ε-constraint algorithm, denoted as A-AUGMECON2, is here proposed to efficiently solve the multi-objective model, by using a novel pruning algorithm that avoids solving redundant optimizations. The method is applied to an isolated community in Uganda. The approach successfully quantifies the trade-off between local long-term impacts, supporting policy makers and local developers in designing effective policies and actions. In particular, our results suggest that the environmental targets can be aligned with the project economics, and that the financial impact of public lighting is limited, which encourages its implementation in electrification projects. Conversely, optimal land use and job creation lead to high economic and environmental costs, highlighting the need for a trade-off for policy and business decision makers. Moreover, the novel A-AUGMECON2 algorithm enables reducing by 48% the computational requirements of the standard AUGMECON2, extending the application of multi-objective methodologies to more complex problems.
•Multi-objective multi-year planning of a rural hybrid power system.•Evaluation of costs, emissions, land use, job creation and public lighting coverage.•Development of Advanced-AUGMECON2 (A-AUGMECON2) for skipping redundant iterations.•The computational burden for identifying the Pareto frontier is reduced by 48%.•Environmental targets show alignment with cost minimization objectives.
•Proposes a model achieving complete integration of European Intra-Day Market rules.•The model can sustain any level of integration of markets with different rules.•The results confirm the ...near-future developments of the actual market.•The building block for evaluating the future evolution of the market is provided.
Currently, the coupling of the European Electricity Markets has been fully achieved for the Day-Ahead Market. In the same time, a joint integrated Intra-Day Market based on the Continuous Trading mechanism is under implementation and it involves countries from West of Europe. However, some countries (e.g. Italy and Iberian countries) use the Discrete Auction mechanism and their integration implies the harmonization of the two trading mechanisms. A Hybrid Mechanism that represents the coordination of Continuous Trading and Discrete Auction has been discussed with two concrete proposals being made by Italy and Iberian countries. Thus, the aim of this paper is to propose an advanced algorithm which can simulate the clearing of the integrated European Intra-Day Market with any levels of coordination between Discrete Auction and Continuous Trading. The proposed model is formulated as a Mixed Integer Linear Problem and incorporates all market rules of both mechanisms. The algorithm is flexible enough to adapt to future changes. In addition, a case study that considers the current and near future market participants and covers an entire day of an Intra-Day Market is run by an iterative process to investigate the impact of the hybrid Intra-Day Market model on the Iberian countries and Italy according to their proposals. Moreover, the test cases represent realistic data in terms of number of variables and constraints, and in terms of complexity of the bids. The results of the paper show that, on one hand, the proposed market clearing model can be applied for different levels of Continuous Trading and Discrete Auction coordination and, on the other hand, the integration into the single European Intra-Day Market of Italy and Iberian countries can be beneficial for them. Therefore, the general conclusion is that the proposed market clearing model can be successfully used by the Power Exchanges currently integrated to solve the market or by the Power Exchanges not yet integrated to evaluate the impact of their future integration. On the other hand, the model can easily cope with any further changes in the market rules and represents a tool for future research, e.g. analysis of market participants behavior in future scenarios or evaluation of various financial instruments to manage the congestion of intra-border interconnectors.
This paper addresses a self-scheduling model for a multi-energy virtual power plant (MEVPP) to optimize its day-ahead energy and reserve schedules considering the participation in joint markets. The ...coordination of energy and reserve services is realized by developing a holistic market framework. MEVPP trades electric energy in day-ahead market and natural gas in natural gas market under the uniform price scheme. MEVPP provides reserve in ancillary service market under the pay-as-bid scheme considering uncertain market clearing prices. Reserve regulations are modeled for the reserve quality provided by MEVPP. MEVPP can sign contracts in capacity market for capacity adequacy. The electricity and natural gas imbalance payments and unsupplied reserve penalty resulting from uncertain PV generation are calculated in real-time. The case studies, based on the practical data from Italian power exchange and transmission system operator, show the economic achievements of MEVPP with multiple markets participation. The advantages of multi-energy coupling in improving flexibility and economic profit are numerically analyzed. MEVPP is proven to be a promising reserve service supplier for TSO. Because through reasonable regulations, the reserve quality of MEVPP can be improved with little impact on its total cost.
•Analyzing the potential flexibility brought by multi-energy carriers coupling for virtual power plant.•Developing a holistic market framework for energy and reserve services.•Considering the impacts of reserve regulations on the quality of reserve service.•Pay-as-bid scheme is considered for ancillary service market.
•Proposed model achieves a complete integration of the European Day-Ahead Market rules.•A single optimization framework is used.•Enhanced the efficiency and fairness of the market solution.•Proposed ...model validation with the realistic data.
Currently, the integration of European Electricity Market (EEM) has led to a single European Day-Ahead Market (DAM) with multiple-areas considered as bidding zones. In the near future, the EEM will spread to the Intra-day and Balancing market. To operate the DAM, a market clearing tool (algorithm) has been developed by market operators. The development of this algorithm corresponds to three primary principles: (i) one single framework, (ii) robust operation, and (iii) individual accountability. However, this algorithm is not available to the research community. In this paper, the authors develop a complete European DAM model in General Algebraic Modelling System (GAMS), formulating it as a Mix Integer Quadratic Constraint Problem (MIQCP) and iterative procedure, to mitigate the non-convexity of electricity prices across Europe due to the “fill or kill” condition of block, complex and Prezzo Unico Nazionale (PUN) orders. Eventually, two case studies reflecting the current European DAM evaluated the model, aiming to confirm its robustness and reliability.
•A stochastic model for the optimal operation of virtual power plants is developed.•The scenario tree contains both market and renewable generation scenarios.•An ad-hoc decomposition method ...drastically reduces the computational time.•Despite optimal solution, PV generation is partially curtailed.•Cogeneration plant can effectively participate in more markets.
As more uncontrollable renewable energy sources are present in the power generation portfolio, the need of more detailed and reliable tools for the optimal operation of energy systems has increased in the last years. This work presents a multi-stage stochastic Mixed Integer Linear Program with binary recourse for optimizing the day-ahead unit commitment of power plants and virtual power plants operating in the day-ahead and ancillary services markets. Scenarios reproduce the uncertainty of the ancillary services market requests, and production of photovoltaic panels. A novel decomposition algorithm is proposed to tackle the challenging multistage stochastic program. The methodology is tested on three types of large power plants: a natural gas-fired combined cycle, a combined heat and power combined cycle with thermal storage, and a virtual power plant integrating a combined cycle with battery and photovoltaic fields. Compared to the typical deterministic unit commitment approach, the proposed stochastic optimization approach allows to increase the revenues of the conventional power plant up to 13.58% and, for the combined heat and power and virtual power plant case, it allows finding a feasible and efficient operational scheduling.
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