mehdi abapour
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Nowadays, large power systems are facing new challenges gifted from emerging and renewable energy resources. This is even worse in developing countries where load is growing rapidly and power systems are relatively weak. With more complex power systems occurrence of a contingency such as unexpected demand during extremely-hot summer days or transient heat waves may lead to voltage drops, cascaded trips and catastrophic wide area blackouts. A few solutions have been proposed, amongst which demand response is known as an effective tool. Demand response programs (DRPs) are implemented on residential, commercial and industrial loads to economically optimize energy systems, improve overall efficiency and reliability, and enhance their stability margins. This paper presents three demand-side management strategies implemented on Iran’s commercial and industrial sectors. Operational reserve programs, incentive-based reduction or disruption of electricity demand during on-peak time intervals, and replacement of traditional lamps with energy efficient ones are applied as three strategic DRPs on industrial and commercial sectors. Three cost-effective solutions are provided for participation of industrial customers in summer peak clipping programs: (a) Transferring the weekend from Friday to one of midweek days, (b) Transferring a part of each co-operated consumer from on-peak demand hours with high electricity tariffs to off-peak time intervals with lower energy prices, (c) DSM by annual overhaul and work suspension. In case of 100 kW power consumption at medium-peak load hours, commercial customer mustat least reduce 10% of this amount at on-peak demand time interval. Economic and environmental benefits obtained from numerical studies are comprehensively provided. It is found that the total asynchronous demand reduction after participation of 287 commercial centers in demand side management programs is equal to 10.187 MW. Total industrial load reduced after implementation of disruption strategy at annual on-peak day (July 20) is equal to 743 MW.Keywords: Demand response programs, commercial, industrial sectors, operational reserve, annual overhaul, work suspension
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افزایش نفوذ منابع انرژی تجدیدپذیر به ویژه منابع بادی با ماهیت احتمالاتی، شبکه های قدرت را با چالش های متعددی از نظر برنامه ریزی و بهره برداری مواجه نموده است. از سوی دیگر، گاز طبیعی به عنوان یک حامل انرژی ارزان و پاک، نقشی موثر در چشم اندازهای بلند مدت انرژی دارد. منابع انعطاف پذیرنوظهور و تکنولوژی-های نوین هماهنگ شده، می توانند با شرکت در بازار برق وگاز روی قیمت برق تاثیرگذار باشند. بر این اساس، در این مقاله استراتژی پیشنهاددهی بهینه قیمت دهی برای یک سیستم ترکیبی متشکل از مزرعه بادی، ذخیره ساز هوای فشرده و تکنولوژی برق به گاز مورد بررسی قرار می گیرد. وجود عدم قطعیت های ناشی از توان بادی و قیمت بازار روز بعد موجب می شود که برنامه ریزی پیشنهادی تحت یک رویکرد احتمالاتی- مقاوم بهینه گردد. توان تولیدی مزرعه بادی با استفاده از رویکرد احتمالاتی مبتنی بر تولید سناریو مدل شد، حال آنکه جهت مدل سازی قیمت بازار روز بعد، یک چارچوب مقاوم ارایه گردید. مدل پیشنهادی جهت حداکثر سازی سود بر روی یک سیستم نمونه پیاده شده است که نتایج حاصل از شبیه سازی نشان دهنده افزایش سود مالک سیستم و استفاده حداکثر از ظرفیت نیروگاه بادی در حضور تکنولوژی برق به گاز و ذخیره ساز هوای فشرده است.
کلید واژگان: استراتژی قیمت دهی، بازار برق، هماهنگی شبکه برق و گاز، نیروگاه بادی، عدم قطعیت، بهینه سازی مقاومWith the high penetration of renewable energy, especially wind power generation with probabilistic nature, the power system is faced with multiple challenges from planning and operation point of view. The need for highly flexible emerging sources like energy storage systems for the integration of renewable energy is essential. Furthermore, the natural gas network as a clean and low-cost energy carrier has an impressive role in the long-term energy perspective. The emergence of new technologies like Power-to-Gas (P2G) and compressed air energy storage (CAES) technologies cause the interdependency between electricity and natural gas networks. An optimal bidding strategy of the hybrid wind farms, CAES and P2G facilities to participate in the day-ahead market is investigated in this paper. The hybrid robust-stochastic approach is implemented to handle the system uncertainties including wind power generation, as well as power market prices to maximize profit. The power generated by the wind farm is modeled by a scenario-based stochastic approach, while day-ahead power price uncertainty to find bidding/ offering curves is modeled by a robust optimization approach. Numerical results indicate an increase in profit, as well as maximum utilization of wind power capacity in the presence of P2G and CAES, simultaneously.
Keywords: Bidding strategy, Wind farms, Uncertainty, robust optimization -
The environmental air pollution according to greenhouse gas emissions and significant demand for electrical energy and water due to the growing population of the world can be mentioned as main challenges all around the world. The current study proposes a new structure for energy-efficient microgrids to deal with on-peak electrical energy load in summer days. Two ancillary services are considered in the proposed structure including solar Stirling engine and diesel plant for decreasing the successive outages of interconnected energy network in extremely-hot weather status and eliminating massive blackouts. Such services are effective solutions to provide load and minimize the whole energy procurement cost as production-side management strategies. The objective of the proposed model is to minimize the fuel cost of the diesel plant and the cost of generated electricity by the local power network considering technical limitations of the combined diesel-Stirling electricity supply system. The optimal employment of solar-based Stirling cycle and diesel engine in providing summer peak power load are evaluated in terms of economic-environmental aspects by applying the model on a test case microgrid, which verifies high performance of the model.
Keywords: Solar dish Stirling heat engine, diesel generation unit, energy-saving, peak load procurement -
Scientia Iranica, Volume:26 Issue: 6, Nov-Dec 2019, PP 3571 -3581
This paper proposes a new cooperative scheduling framework for demand response aggregators (DRAs) and electric vehicle aggregators (EVAs) in a day-ahead market. The proposed model implements the information-gap decision theory (IGDT) to optimize the scheduling problem of the aggregators, which guarantees obtaining the predetermined profit by the aggregators. In the proposed model, the driving pattern of electric vehicle owners and the uncertainty of day-ahead prices are simulated via scenario-based and a bi-level IGDT based methods, respectively. The DR aggregator provides DR from two demand side management programs including time-of-use (TOU) and reward-based DR. Then, the obtained DR is offered into day-ahead markets. Furthermore, the EVA not only meet the EV owners’ demand economically, but also participates in the day-ahead mark while willing to set DR contracts with the DR aggregator. The objective function is to maximize the total profit of DR and EV aggregators perusing two different strategies to face with price uncertainty, i.e., risk-seeker strategy and risk-averse strategy. The proposed plan is formulated in a risk-based approach and its validity is evaluated on a case study with realistic data of electricity markets.
Keywords: Demand response aggregator, electric vehicles aggregator, cooperative framework, information-gap decision theory, uncertainty -
Nowadays, energy supplied by the reliable manner is one of the important challenges of the distribution company in the radial distribution system. Therefore, this paper considers these challenges by the optimal DG placement to minimize power losses with considering the analysis related to the reliability and voltage profile. In this paper, exchange market algorithm (EMA) as a powerful tool is used to solve the optimization problem. In order to extract the global optimum point, EMA uses two searching operators and two absorbent operators based on the generation of random numbers. To evaluate the goals of this paper, EMA is successfully implemented on 10, 33, and 69 bus IEEE test systems. Simulation results illustrated that power losses are reduced by the optimal DG placement and sizing. Finally, obtained results analysis concluded that system reliability and voltage profile will be improved if the DGs are allocated optimally in the radial network.Keywords: Distributed Generation, Power Loss Reduction, Reliability Improvement, Exchange Market Algorithm, Voltage Profile Improvement
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Due to increasing use of renewable energy sources, employing dc/dc converters as interface is proliferated. Among various dc/dc topologies, utilizing multi-input converters due to higher reliability and flexibility is more widespread. This paper evaluates the reliability of the multi-input dc/dc converter, besides carrying out cost calculation to achieve the cost-effective and reliable converter. Furthermore, diagrams of various reliability factors versus the converter’s branches are demonstrated based on mathematical equations and simulation values for both of the parallel and standby redundant modes in order to reach an optimal number of branches in each mode. The results show that the optimal number of branches in terms of reliability or cost factor is different and can vary based on some parameters like output power or component’s type.
Keywords: Multi-input DC, DC converter, Reliability calculation, Cost optimization, Renewable energy -
آرایش های کلیدهای قدرت به صورت موازی، سری و آماده به کار با هدف بهبود قابلیت اطمینان در مبدل های الکترونیک قدرت به کار می روند. افزایش قابلیت اطمینان در کاربردهای نظیر مبدل های توان بالای صنعتی، ماهواره ها، مبدل های واسط در حضور منابع تولید پراکنده به دلایل اقتصادی، عدم دسترسی و یا دسترسی سخت برای تعمیر و نگه داری و همچنین دلایل جانی اهمیت به خصوص دارد. به دلیل اهمیت قابلیت اطمینان، در این مقاله، مدل های قابلیت اطمینان ساختارهای موازی، سری و آماده به کار و همچنین ساختار جدید پیشنهادی با نگرشی جدید مورد مقایسه قرار گفته اند. توابع قابلیت اطمینان و MTTF (متوسط زمان خطا) برای ساختارهای مذکور به دست آمده است. در برخی موارد، ساختارهای مازاد مورد مطالعه دارای نواحی مرزی با یکدیگر هستند که در کار حاضر این نواحی مرزی تعیین گردیده است. نتایج تحلیل های صورت گرفته موید آن است که در کاربردهای توان بالا، ساختار سری و موازی به ترتیب برای موارد ولتاژ بالا و جریان بالا مناسب بوده و همچنین ساختار جدید می تواند جایگزین ساختار آماده به کار شود.کلید واژگان: آرایش کلیدهای قدرت، قابلیت اطمینان، MTTF، ساختارهای مازادJournal of Iranian Association of Electrical and Electronics Engineers, Volume:15 Issue: 1, 2018, PP 89 -102Parallel, standby and series configurations are different types of power switch configuration that can be considered in semiconductor switches to improve the reliability of power electronic converters and theirs lifetime, especially in specific application such as high power industrial applications, satellites, power electronic interface for renewable energies and etc. In this paper, the reliability models of series traditional configuration and the new type are developed based on the Markov process. The mean time to failure (MTTF) of series and new configuration are derived. The reliability and MTTF of triple and new configuration are compared together. In some cases, some redundancy configurations have the same MTTF in a boundary condition. The analytical result illustrated that the new configuration is a suitable alternative instead of the standby configuration. The result showed the series and parallel configuration are suitable for high voltage and high current applications .
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