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Error Analysis of CORDIC Processor with FPGA Implementation |
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Young-Man Kim(Liberty University, United States) |
| The coordinate rotation digital computer (CORDIC) is a shift-add based fast computing algorithm which has been found in many digital signal processing (DSP) applications. In this paper, a detailed error analysis based on mean square error criteria and its implementation on FPGA is presented. Two considered error sources are an angle approximation error and a quantization error due to finite word length in fixed-point number system. The error bound and variance are discussed in theory. The CORDIC algorithm is implemented on FPGA using the Xilinx Zynq-7000 development board called ZedBoard®. Those results of theoretical error analysis are practically investigated by implementing it on FPGA. |
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A Bifurcation Study of Droop-Controlled Inverter-Based Microgrids with Dynamic Loads |
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Der-Cherng Liaw, Sheng-Jie Huang(National Yang Ming Chiao Tung University, Taiwan) |
| The paper studies the dynamical behavior of droop-controlled inverter-based microgrids with dynamic loads. A result for determining the corresponding local stability property of the system at each equilibrium point is derived. Sufficient conditions for the parameters to ensure system stability of the microgrids are also obtained. Saddle-node bifurcation was found to occur while the reactive power demand increases to the stability limit of the system. Existence conditions for such an unstable phenomenon are calculated by employing the bifurcation theory on the proposed system model. Numerical simulations for a six-order testing system have demonstrated the validity of the proposed results. |
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Reinforcement Learning Based Electricity Price Controller in Smart Grids |
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Yi-Hsin Lin, Wei-Yu Chiu(National Tsing Hua University, Taiwan) |
| Striking a balance between power supply and demand is the most imperative target for any electricity grid system. In order to address variability of renewable energy in the modern grid, a robust and elastic balancing scheme is required. Conventional model-based approaches can suffer from great performance degradation given the uncertainty induced by the renewable energy. As such, this study explores a model-free approach by proposing a reinforcement learning based pricing scheme that balances the power supply and demand. A price signal is considered as the control signal for the balance management. Case studies were conducted to show the effectiveness of the proposed methodology. |
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Distributed Coordination Algorithm for Economic Dispatch Problem in Microgrid Network with Battery |
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Sesun You, Jaeyun Yim(Chung-Ang University, Korea), Youngwoo Lee(Chonnam National University, Korea), Wonhee KIM(Chung-Ang University, Korea) |
| In this paper, the distributed coordination algorithm for EDP
with battery is proposed to consider the over/less energy generations problem. The initialization-free distributed algorithm is applied to minimize the local generation cost and power-supply demand balance with constraints. The consensus laws was applied to compute the over/less energy in distributed manner. The virtual constraint range of each node is coordinated according to over/less energy. Therefore, as the infeasible EDP convert to feasible EDP by varying virtual constraint, the virtual solution approximate the optimal power generation solution. The performance of the proposed method is validated via numerical simulation. |
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Sine-Sweep Input Generation With Minimum Energy Restriction for Obtaining a Precise Frequency Response Function in Industrial Servo Systems |
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Tae-Ho Oh, Ji-Seok Han, Young-Seok Kim, Dae-Young Yang, Tae-Hoon Kim(Seoul National University, Korea), Sang-Hoon Lee(RS Automation, Korea), Dong-Il Dan Cho(Seoul National University, Korea) |
| This paper presents a sine-sweep input generation method to obtain a precise frequency response function (FRF) in industrial servo systems. In the proposed algorithm, the sine-sweep input is generated in real-time considering the energy of the input signal for each frequency. Using real industrial servo systems, it is demonstrated that the proposed sine-sweep input generation algorithm effectively obtains very accurate FRFs for various types of systems. |
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