Browsing by Author "Rashmi, n."

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A Novel Approach for Steady State Calculations of VSC-HVDC Connected PMSG Based Offshore Wind Farms Integrated into Multi-Machine Systems
(Taylor and Francis Ltd., 2023) Rashmi, n.; Gaonkar, D.N.
Offshore wind farms equipped with Direct Drive Permanent Magnet Synchronous Generators (DD-PMSG) are drawing increased attention due to their advantage over other variable speed technologies. VSC-HVDC links are considered the most suitable option for transferring power to the onshore system. The integration of VSC-HVDC connected DD-PMSG based offshore wind farms into multi-machine systems is explored in this paper. A novel approach for power flow and initial condition calculations is proposed to facilitate dynamic analysis of the system. For three cases of the most commonly specified quantities of the wind farm, efficient methods have been described. The cases comprise combinations of data like the total output of the wind farm, the number of wind turbines, the wind speed, or the output of individual wind turbine, which are frequently given in literature. This approach enables the user to build the dynamic model of the system in any basic graphical dynamic modeler and numerical computational software without requiring power system toolboxes or electromagnetic transient packages. The proposed methods are highly effective for studies focusing primarily on the dynamic aspects and controls of the system. Case studies and simulations are conducted to verify the proposed technique. © 2023 Taylor & Francis Group, LLC.
A Novel Simplified Modeling Approach for VSC-HVDC Links in Performance Analysis of Multi-Machine Systems
(Springer Nature, 2024) Rashmi, n.; Gaonkar, D.N.
In this paper, a simplified model of voltage source converter-based high-voltage direct current (VSC-HVDC) link is proposed that is effective in the analysis of multi-machine systems, even when crucial applications of the link are involved. The model is derived by eliminating the DC dynamics, including the converter-related impedances as a part of the AC system transmission network and obtaining the converter currents in a straightforward manner. Case studies are conducted on 4-machine, 10-bus and 16-machine, 68-bus systems to prove the accuracy of the model. The study clearly indicates the model’s ability to reproduce the influence of VSC controllers, impact of variable power levels and effects of multiple HVDC links in a system. It is further verified for significant VSC-HVDC applications. The model is effective at handling frequency support of asynchronous systems and can be applied to VSC-HVDC connected offshore wind farms feeding multi-machine systems. It is demonstrated that the proposed model can be efficiently used for analysis of large AC systems embedded with VSC-HVDC links with lesser modeling complexity and computation time. © King Fahd University of Petroleum & Minerals 2023.
Dynamic modelling of a double-cage induction machine for analysis with WECS
(Institute of Electrical and Electronics Engineers Inc., 2017) Rashmi, n.; Shubhanga, K.N.
This paper presents the development of a 7th order and a 5th order model for a double-cage induction machine that can be used in the context of power system analysis involving wind eneregy conversion systems (WECS). Through a series of case studies a comparison is made between the double-and single-cage models of an induction machine to show that the double-cage structure offers higher starting torque characteristics. Further, it is shown that at low frequency oscillations which are dominant in power swing studies, both the models behave almost identically. Â© 2017 IEEE.
Effect of Primary VSC-HVDC Controls on the Performance of Ancillary Frequency Control Strategies
(Institute of Electrical and Electronics Engineers Inc., 2022) Rashmi, n.; Gaonkar, D.N.
This paper analyses the impact of active and reactive power controls of VSC-HVDC on the behaviour of frequency controllers. The performance of droop and PI type frequency control strategies are investigated. The effect of feedforward and feedback active power loops are examined through bandwidth analysis. The influence of reactive power controllers on the performance is also studied. Inferences are drawn through MATLAB/SIMULINK based time domain simulations. Â© 2022 IEEE.
Modelling and Performance Analysis of Synchronous and Asynchronous Links Integrated into Multi-Machine Systems
(Institute of Electrical and Electronics Engineers Inc., 2022) Rashmi, n.; Gaonkar, D.N.
The performance analysis of synchronous and asynchronous multi-machine systems with tie-lines as Line Commutated Converter based High Voltage Direct Current links (LCCHVDC) or Thyristor Controlled Series Capacitor (TCSC) lines is presented in this paper. Detailed inferences are drawn for the systems subjected to various dynamic events. The effect of variation of synchronous tie-line power levels on the modal behaviour is investigated. The asynchronous system modes are analysed with reference to the modes of its synchronous counterparts. Eigenvalue analysis of the systems are obtained through prony analysis which avoids the need of in-depth analytical computations. Â© 2022 IEEE.
Rotor speed-instability performance of type-1 WECS employing double-cage induction generator
(Institute of Electrical and Electronics Engineers Inc., 2017) Rashmi, n.; Shubhanga, K.N.
In this paper, the interfacing of the type-1 wind turbine employing double cage induction generator to the grid is presented. Rotor instability performance of this system is studied and a detailed comparison is done with the single-cage. Steady-state torque-speed characteristics are compared and the results are validated through transient and eigenvalue analysis. The effect of wind turbine characteristics on rotor stability has been brought out. Â© 2017 IEEE.