Amirkabir University of Technology

About: Amirkabir University of Technology is a education organization based out in Tehran, Iran. It is known for research contribution in the topics: Nonlinear system & Finite element method. The organization has 15254 authors who have published 31165 publications receiving 487551 citations. The organization is also known as: Tehran Polytechnic & Tehran Polytechnic University.

A Decentralized Power Management and Sliding Mode Control Strategy for Hybrid AC/DC Microgrids including Renewable Energy Resources

Abstract: This paper presents a new decentralized robust strategy to improve small and large-signal stability and power-sharing of hybrid AC/DC microgrids and improve its performance for nonlinear and unbalanced loads. In addition to the sliding mode controller for DC/DC converters, for the sake of improving power sharing and regulating active and reactive powers injected by distributed energy resources, and moreover, controlling harmonic and negative-sequence current in the presence of nonlinear and unbalanced loads, two separate controllers for positive sequence power control and negative sequence current control are designed based on the sliding mode control and Lyapunov function theory, respectively. The theoretical concept of the proposed robust control strategy, including mathematical modeling of microgrid components, basic theorems, controller design procedure, and robustness and closed loop stability analysis are outlined. Also, this direct power/current/voltage control scheme is governed by a new hybrid AC/DC hierarchical control scheme that exploits a harmonic virtual impedance loop and voltage compensation scheme. To show the effectiveness of the proposed robust control scheme, offline time-domain simulations are done on a hybrid AC/DC wind/photovoltaic/fuel-cell microgrid with nonlinear and unbalanced loads in MATLAB/Simulink environment, and the results are experimentally verified by OPAL-RT real-time digital simulator.

New Application of SWARA Method in Prioritizing Sustainability Assessment Indicators of Energy System

Abstract: A major topic among the current researches on energy is a sustainable energy development and assessment. An importance of energy system is obvious in our life. There are many important energy applications. There are heating and cooling, power generation, desalination, air conditioning and so on. By the year 2020 world will need 50% more energy than today and the Asia-Pacific region will become world's largest consumer of energy. In 21-st century, world faces with the challenge of converting its fossil fuels energy base to the sustainable energy sources. Regarding the increasing rise of the energy demand and consumption, virtually everyone in the world must implement an integrated resource planning (IRP). It is vitally important to achieve sustainable growth. Sustainability assessment of energy system is one of the important issues in policy making all around the world. Decision making on energy system is very risky and difficult and therefore cannot be individual. Multi Criteria Decision Making (MCDM) is a renowned methodology in decision making and evaluation. Some of the most famous MCDM tools are as following: AHP, ANP, TOPSIS, ELECTRE, MUSA, AKUTA, VIKOR, PROMETHEE, SAW, MOORA, COPRAS, COPRAS-G, SWARA, FARE. A Step-wise Weight Assessment Ratio Analysis (SWARA) method is one of the new MCDM methods presented in 2010. SWARA method is applied for some reasons in this paper. Firstly, SWARA’s perspective is different from other similar methods like AHP, ANP and FARE. SWARA gives the chance for decision and policy makers to select their priority based on the current situation of environment and economy. In this method, expert has an important role on evaluations and calculating weights. The ability to estimate experts’ opinion about importance ratio of the criteria is the main element of this method. SWARA is developed for identifying importance of criteria and relative weights of each criterion. Current research applies SWARA as a new framework for evaluating and prioritizing sustainability assessment indicators of energy system. General indicator system consists of Resource Indicator, Environment Indicator, Economic Indicator and Social Indicator and their sub-criterions. For instance, complex environmental indicator consists of CO2, SO2 and NOX indicators while complex economic indicator consists of energy costs, investment and efficiency indicators. The research revealed that the most important indicator is Social (0.342). Then, the range of indicators is as following: Environmental (0.284), Economic (0.212) and Resource (0.162). Finally, the research shows that this methodology can be useful as a framework to operate with sustainability assessment indicators of the energy system. Also, this methodology can be used for decision making in real issues of future researches in different areas. The results of this methodology also can be compared to other methods such as AHP and ANP. DOI: http://dx.doi.org/10.5755/j01.ee.24.5.4526