The Experts below are selected from a list of 57 Experts worldwide ranked by ideXlab platform
Chengyong Zhao - One of the best experts on this subject based on the ideXlab platform.
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Investigation of Small-Signal Dynamics of Modular Multilevel Converter Under Unbalanced Grid Conditions
IEEE Transactions on Industrial Electronics, 2019Co-Authors: Chunyi Guo, Jiayi Yang, Chengyong ZhaoAbstract:This paper develops a comprehensive dynamic-phasor-based small-signal model for the modular multilevel converter (MMC) system under unbalanced grid conditions, which takes into consideration the dynamics of the MMC system under a balanced grid condition as well as the other emerging internal harmonics produced by the unbalanced grid components and more complex controllers. The small-signal model is validated by comparing the time-domain responses from a detailed electromagnetic transient (EMT) simulation in PSCAD/EMTDC. Based on the eigen-analysis and PSCAD-based time-domain simulation studies, this paper reveals the poorly damped modes that cause unstable oscillations in MMC system under the unbalanced grid conditions. From the results, more poorly damped modes involved in the internal harmonics are emerging under unbalanced grid conditions compared with the modes under the balanced grid conditions, and can highly impact the system dynamic behaviors by the selection of the control parameters. It is also shown that, under the unbalanced grid conditions, the feasible region of the control parameters of the vector current control gets narrowed indicating the reduction of the stability margin, smaller (larger) value of proportional (integral) Gain of the circulating current suppressing controller can enhance the system stability, and larger values of the proportional and integral Gains of the negative-sequence current suppressing control can result in the harmonic instability of the MMC system. Besides, the parameters of multiple complex-coefficient filters for positive- and negative-sequence components extraction also have a big impact on the small-signal stability of the MMC system and are required to be properly selected.
Chunyi Guo - One of the best experts on this subject based on the ideXlab platform.
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Investigation of Small-Signal Dynamics of Modular Multilevel Converter Under Unbalanced Grid Conditions
IEEE Transactions on Industrial Electronics, 2019Co-Authors: Chunyi Guo, Jiayi Yang, Chengyong ZhaoAbstract:This paper develops a comprehensive dynamic-phasor-based small-signal model for the modular multilevel converter (MMC) system under unbalanced grid conditions, which takes into consideration the dynamics of the MMC system under a balanced grid condition as well as the other emerging internal harmonics produced by the unbalanced grid components and more complex controllers. The small-signal model is validated by comparing the time-domain responses from a detailed electromagnetic transient (EMT) simulation in PSCAD/EMTDC. Based on the eigen-analysis and PSCAD-based time-domain simulation studies, this paper reveals the poorly damped modes that cause unstable oscillations in MMC system under the unbalanced grid conditions. From the results, more poorly damped modes involved in the internal harmonics are emerging under unbalanced grid conditions compared with the modes under the balanced grid conditions, and can highly impact the system dynamic behaviors by the selection of the control parameters. It is also shown that, under the unbalanced grid conditions, the feasible region of the control parameters of the vector current control gets narrowed indicating the reduction of the stability margin, smaller (larger) value of proportional (integral) Gain of the circulating current suppressing controller can enhance the system stability, and larger values of the proportional and integral Gains of the negative-sequence current suppressing control can result in the harmonic instability of the MMC system. Besides, the parameters of multiple complex-coefficient filters for positive- and negative-sequence components extraction also have a big impact on the small-signal stability of the MMC system and are required to be properly selected.
Jiayi Yang - One of the best experts on this subject based on the ideXlab platform.
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Investigation of Small-Signal Dynamics of Modular Multilevel Converter Under Unbalanced Grid Conditions
IEEE Transactions on Industrial Electronics, 2019Co-Authors: Chunyi Guo, Jiayi Yang, Chengyong ZhaoAbstract:This paper develops a comprehensive dynamic-phasor-based small-signal model for the modular multilevel converter (MMC) system under unbalanced grid conditions, which takes into consideration the dynamics of the MMC system under a balanced grid condition as well as the other emerging internal harmonics produced by the unbalanced grid components and more complex controllers. The small-signal model is validated by comparing the time-domain responses from a detailed electromagnetic transient (EMT) simulation in PSCAD/EMTDC. Based on the eigen-analysis and PSCAD-based time-domain simulation studies, this paper reveals the poorly damped modes that cause unstable oscillations in MMC system under the unbalanced grid conditions. From the results, more poorly damped modes involved in the internal harmonics are emerging under unbalanced grid conditions compared with the modes under the balanced grid conditions, and can highly impact the system dynamic behaviors by the selection of the control parameters. It is also shown that, under the unbalanced grid conditions, the feasible region of the control parameters of the vector current control gets narrowed indicating the reduction of the stability margin, smaller (larger) value of proportional (integral) Gain of the circulating current suppressing controller can enhance the system stability, and larger values of the proportional and integral Gains of the negative-sequence current suppressing control can result in the harmonic instability of the MMC system. Besides, the parameters of multiple complex-coefficient filters for positive- and negative-sequence components extraction also have a big impact on the small-signal stability of the MMC system and are required to be properly selected.
Diego Patino - One of the best experts on this subject based on the ideXlab platform.
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Modeling and control of water booster pressure systems as flexible loads for demand response
Applied Energy, 2017Co-Authors: Cesar O. Diaz, Fredy Ruiz, Diego PatinoAbstract:Abstract Water Booster Pressure Systems (WBPSs) are responsible for supplying water and maintaining pressure in a building pipeline. These systems are potentially useful to offer energetic services required by the System Operator (SO) through demand response, considering the spread use of these hydraulic devices in high-rise buildings. In this article, a dynamic model for a WBPS is developed in order to evaluate it as a flexible load for demand response applications. The model is built from first-principles and tuned with experimental data of air pressure, power consumption and water flow, obtaining an error of 1.11% in the energy demand between the experimental and the simulated data. It is shown that the WBPS can operate as a flexible load by changing the pressure set point. Additionally, it is achieved a flexibility of 27% in the energy power consumption without stopping the water flow in the building and it is shown that WBPS can provide Spinning Reserve Services. Finally, this work proposes an aggregator of systems, based on a Proportional-Integral Gain Scheduling controller, that can track the SO requirements with an error lower than 0.86%.
Jiang-hui Zhang - One of the best experts on this subject based on the ideXlab platform.
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Necessary and sufficient condition-based stability analysis for Proportional-Integral TCP/AQM networks
2009 Chinese Control and Decision Conference, 2009Co-Authors: De-jin Wang, Jiang-hui ZhangAbstract:This article addresses the stability analysis for TCP networks with Proportional-Integral (PI) AQM scheme based on a graphical necessary and sufficient stability criterion. A linearized second-order fluid-flow TCP model is adopted and the stability region is drawn in the Proportional-Integral Gain space of PI AQM strategy. Then, we relate the network parameters with the PI controller parameters, and the boundaries relations between these two kinds of parameters are obtained, which do not have any conservatism and exhibit how the PI parameters affect the stability of networks. Finally, different stability conditions are compared using both Matlab and NS-2 simulations to show the superiority of our necessary and sufficient condition-based stability analysis over the Lyapunov sufficient condition-based results.
