Control
Zahra Shabani; Haleh Tajadodi
Abstract
In this paper, a numerical technique is proposed to solve optimal control problems (OPCs) of Volterra integral equations (VIEs). We apply the linear B-spline polynomials to solve OPCs by VIEs. The B-spline function divides the interval into sub-intervals and then built a different approximating polynomial ...
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In this paper, a numerical technique is proposed to solve optimal control problems (OPCs) of Volterra integral equations (VIEs). We apply the linear B-spline polynomials to solve OPCs by VIEs. The B-spline function divides the interval into sub-intervals and then built a different approximating polynomial on each sub-interval. In this method, optimal trajectory and control functions are expanded in terms of B-spline functions. The linear B-spline operational matrix of integration and multiplication are utilized in the proposed method.The main characteristic this method is that by using the suggested numerical technique and the related operational matrices, optimal control problem governed by Volterra integral equations is converted to a system of equations. Suffice it to say that this scheme simplifies The main problems and also makes to obtain a good approximate solution for them. In the end, there are two illustrative examples which numerical results show the validity and applicability of our method.
Industrial Electronics
Ahmad Khajeh; Zahra Shabani
Abstract
The Doubly-Fed Induction Generators (DFIG) based Wind Turbines (WT) are widely used in WTs connected to power systems. Traditionally the back-to-back converters are used in order to control the DFIG. In this paper, an Indirect Matrix Converter (IMC) is utilized. Compared with back-to-back converters, ...
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The Doubly-Fed Induction Generators (DFIG) based Wind Turbines (WT) are widely used in WTs connected to power systems. Traditionally the back-to-back converters are used in order to control the DFIG. In this paper, an Indirect Matrix Converter (IMC) is utilized. Compared with back-to-back converters, IMCs have numerous advantages such as: higher level of robustness, reliability, reduced size and weight due to the absence of bulky electrolytic capacitor. According to the recent grid codes it is required that wind turbines remain connected to the grid during grid faults. It means that the plant must be in operation and be able to tolerate the fault conditions. This feature is called Fault Ride-Through (FRT) capability of wind plants. To improve FRT capability of the wind turbine, in this paper an adaptive gain scheduling controller is proposed. The proposed method could increase the damping of fault currents and hence attribute more time to controller for reactive power injection. Therefore, the new FRT standards are satisfied. PSIM simulation results confirm the efficiency of the proposed method.
