Modeling of multi-junction photovoltaic cell using MATLAB/Simulink to improve the conversion efficiency
- Authors: Das, Narottam , Wongsodihardjo, Hendy , Islam, Syed
- Date: 2015
- Type: Text , Journal article
- Relation: Renewable Energy Vol. 74, no. (2015), p. 917-924
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- Description: This paper focuses on modeling of multi-junction solar cell (MJSC) to improve the conversion efficiency using MATLAB/Simulink software. The multi-junction photovoltaic (PV) cell is investigated to obtain its maximum performance compare to the conventional silicon PV cell. MATLAB/Simulink modeled results show that tandem cell can provide almost 3-times maximum power compared to the conventional PV cells. Maximum power point tracker (MPPT) has also been performed to improve the conversion efficiency of the PV systems. The MPPT is able to assist the PV cells to attain more power efficiently and deliver electricity to the grid.
Risk constrained short-term scheduling with dynamic line ratings for increased penetration of wind power
- Authors: Banerjee, Binayak , Jayaweera, Dilan , Islam, Syed
- Date: 2015
- Type: Text , Journal article
- Relation: Renewable Energy Vol. 83, no. (2015), p. 1139-1146
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- Description: Limited transmission capacity may lead to network congestion which results in wind curtailment during periods of high availability of wind. Conventional congestion management techniques usually involve generation management which may not always benefit large wind farms. This paper investigates the problem in detail and presents an improved methodology to quantify the latent scheduling capacity of a power system taking into account stochastic variation in line-thermal rating, intermittency of wind, and mitigating the risk of network congestion associated with high penetration of wind. The mathematical model converts conventional thermal constraints to dynamic constraints by using a discretized stochastic penalty function with quadratic approximation of constraint relaxation risk. The uniqueness of the approach is that it can limit the generation to be curtailed or re-dispatch by dynamically enhancing the network latent capacity as per the need. The approach is aimed at strategic planning of power systems in the context of power systems with short to medium length lines with a priori known unit commitment decisions and uses stochastic optimization with a two stage recourse action. Results suggest that a considerable level of wind penetration is possible with dynamic line ratings, without adversely affecting the risk of network congestion.
Security of energy supply with change in weather conditions and dynamic thermal limits
- Authors: Jayaweera, Dilan , Islam, Syed
- Date: 2014
- Type: Text , Journal article
- Relation: IEEE Transactions on Smart Grid Vol. 5, no. 5 (2014), p. 2246-2254
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- Description: Aging network assets, significant variations in weather conditions, increased accommodation of intermittent distributed generation, and the network operating patterns deviate actual thermal limits of assets from deterministic thermal limits. In that context, the paper proposes a model integrated innovative approach to assess the security of energy supply in an active distribution network. The approach integrates models of dynamic thermal limits, stochastic variations in weather conditions, random outages, intermittent generation outputs, and random load fluctuations into Monte Carlo simulation and quantifies the level of insecurity. The effectiveness of the approach is demonstrated by a case study. The results suggest that costs of outages can be significantly affected by combinatorial effects of weather patterns and dynamic thermal limits. Changes in weather patterns contribute more to the costs of the outages than dynamic variations in thermal limits. Latent capacities of assets do not necessarily reduce insecurity of energy supply. The paper also argues that assets in stressed distribution networks should be modeled with dynamic thermal limits for the quantification of true impacts.
Digital implementation of a fault emulator for transient study of power transformers used in grid connection of wind farms
- Authors: Mesbah, Mohsen , Moses, Paul , Islam, Syed , Masoum, Mohammad
- Date: 2013
- Type: Text , Journal article
- Relation: IEEE Transactions on Sustainable Energy Vol. 5, no. 2 (2013), p. 646-654
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- Description: A real-time digital hardware simulation tool is developed to study the transient performance of three-phase power transformers used in grid connected wind farms. Using vector-based analysis for generating different voltage components, the fault simulator is capable of emulating a multitude of grid connection disturbances such as voltage sag, voltage swell, voltage unbalance, harmonics, dc-bias, and phase jump. This enables realistic real-time evaluation of power system faults and their impacts on critical components such as the interconnection transformers used in wind farms. In this paper, the proposed fault simulator has been employed to conduct an experimental study of the effects of balanced and unbalanced fault conditions on a three-phase three-leg power transformer. The transient current response of three-phase transformers subject to symmetrical/unsymmetrical faults is a complex issue due to the influences of multiple flux paths interacting within the core as well as ferromagnetic nonlinearities and core-structure asymmetry. So far, existing studies of this behavior have been restricted to computer modeling simulations with limited experimental work performed. The main contributions of this paper are to 1) present a new versatile fault simulator using a space vector modulation control approach to generate typical grid disturbances, and 2) apply the fault emulator to study the transient behavior of three-phase power transformers under various fault conditions common to wind farm interconnection transformers. The paper also discusses design, component selection, digital signal processing (DSP), and implementation aspects.