Wyniki wyszukiwania - BazTech

1

A comparative study of grid-following and grid-forming control schemes in power electronic-based power systems

Gao Xiao, Zhou Dao, Anvari-Moghaddam Amjad, Blaabjerg Frede

Power Electronics and Drives

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2023

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Vol. 8 (43)

1--20

EN

Along with de-carbonisation, the penetration of power electronic converters has increased, and the power system has become a power electronic-based power system. In such a situation, the stability of the power system faces great challenges. In the event of a large disturbance, the power grid will lack the ability to maintain a stable voltage and frequency. In order to improve the stability of the power grid, the traditional grid-following (GFL) control is needed to be converted to the grid-forming (GFM) control. This paper analyses the control schemes of the GFL and GFM converters by investigating their state-space models, and the eigenvalue trajectories of both control schemes are shown to analyse the stability of the systems. Moreover, a case study is exemplified to compare the performance of the two control strategies while responding to frequency disturbances. Finally, a time-domain simulation model of a 15 kW grid-connected converter is built in Matlab/Simulink to benchmark the performance of the GFL and GFM converters under different working conditions. The result reveals that the GFL converter may encounter some instabilities when applied in power electronic-based systems, while the GFM converter is more suitable for the weak power grid.

2

Performance evaluation and frequency response analysis of a two stage two spool electrohydraulic servovalve with a linearized model

Mondal Nitesh, Datta Biswanath

Engineering Transactions

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2019

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Vol. 67, iss. 3

411--427

EN

This article focuses on the performance study and frequency response analysis with the state space model of a linearized two stage two spool non-conventional electrohydraulic servovalve from a set of nonlinear state equations. The performance of this valve depends on many valve geometries and fluid parameters. This non-conventional electrohydraulic servovalve is controlled by a pressure controlled pilot, which generates a differential pressure between the upper and lower chambers of two spools. This differential pressure acts as the feedback element, thereby reducing the requirement for a feedback wire. In this paper, the dynamic behaviour and state-space model of the valve is established with the aid of linearized mathematical equations and the coefficients of the equations directly depend on the valves parameters, fluid properties and flow properties. The dynamic performance of this valve and the frequency response are analysed with the help of MATLAB/Simulink.

3

Electromechanical System for Charging Batteries of Electric Cars

Trzaska Z.

Machine Dynamics Research

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2018

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Vol. 42, No. 1

165--179

EN

An electric vehicle battery charger based on the Faraday disk generator is developed in this paper to reduce the amount of time it takes for the rotational energy to be converted into electrical energy. The kinetic energy of the generator during charging is transformed effectively into electric energy by rotating the compact formed from the disk permanent magnet and conducting shield by means of an electric motor supplied from the power grid using possibly renewable energy sources. One of the advantages of the Faraday disk generator is its high power capability, which is applicable for high rate of charging and reducing the amount of time it takes for the rotational energy to be converted into electrical energy. Computer simulations have been performed for various sets of the charger element parameters and after selecting the obtained results, the optimal set was established. Simulation results for charging processes corresponding to the optimal element parameter tests are included.

4

Offset-free nonlinear Model Predictive Control with state-space process models

Tatjewski P.

Archives of Control Sciences

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2017

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Vol. 27, no. 4

595--615

EN

Offset-free model predictive control (MPC) algorithms for nonlinear state-space process models, with modeling errors and under asymptotically constant external disturbances, is the subject of the paper. The main result of the paper is the presentation of a novel technique based on constant state disturbance prediction. It was introduced originally by the author for linear state-space models and is generalized to the nonlinear case in the paper. First the case with measured state is considered, in this case the technique allows to avoid disturbance estimation at all. For the cases with process outputs measured only and thus the necessity of state estimation, the technique allows the process state estimation only - as opposed to conventional approach of extended process-and-disturbance state estimation. This leads to simpler design with state observer/filter of lower order and, moreover, without the need of a decision of disturbance placement in the model (under certain restrictions), as in the conventional approach. A theoretical analysis of the proposed algorithm is provided, under applicability conditions which are weaker than in the conventional approach. The presented theory is illustrated by simulation results of nonlinear processes, showing competitiveness of the proposed algorithms.

5

Analysis of State-Space Model based Voice Conversion

Sun J., Zhang X.

Przegląd Elektrotechniczny

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2011

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R. 87, nr 10

373-376

EN

A new State-Space Model (SSM) based voice conversion method has been proposed recently which outperforms the traditional Gaussian Mixture Model (GMM) method. Although the implementation process of the new method has been elaborated, the theoretical essence of this method has not been analysed clearly. In this paper an exhaustive analysis of the SSM based method is given theoretically and experimentally. Through these analysis, much simpler equivalence form and performance upper bound of the new method are obtained. Finally possible improvements are discussed.

PL

Przedstawiono teoretyczna i eksperymentalną analizę nowego algorytm SSM przetwarzania sygnału mowy.