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A novel conversion technique from nodal to edge finite element data structure for electromagnetic analysis

Kamireddy Durgarao, Nandy Arup

Computer Assisted Methods in Engineering and Science

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2021

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Vol. 28, no. 4

291--319

EN

Standard nodal finite elements in the electromagnetic analysis have a well-known limitation of the occurrence of a spurious solution. In order to circumvent the problem, a penaltyfunction method or a regularization method is used with the potential formulation. Thesemethods solve the problem partially by pushing the spurious mode to the higher end of thespectrum. But it fails to capture singular eigenvalues in the case of the problem domainswith sharp edges and corners. To circumvent this limitation, edge elements have beendeveloped for the electromagnetic analysis where degree of freedom is along the edges.But most of the preprocessors develop complex meshes in the nodal framework. In thiswork, we have developed a novel technique to convert nodal data structure to edge datastructure for electromagnetic analysis. We have explained the conversion algorithm in details, mentioning associated complexities with relevant examples. The performance of thedeveloped algorithm has been demonstrated extensively with several examples.

2

Subsynchronous oscillation and its mitigation of VSC-MTDC with doubly-fed induction generator-based wind farm integration

Su Miaohong, Dong Maiying, Liu Kaiqi, Zou Weiwei

Archives of Electrical Engineering

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2021

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Vol. 70, nr 1

53--72

EN

Wind power integration through the voltage source converter-based high-voltage direct current (VSC-HVDC) system will be a potential solution for delivering large-scalewind power to the “Three-North Regions” of China. However, the interaction between the doubly-fed induction generator (DFIG) and VSC-HVDC system may cause the risk of subsynchronous oscillation (SSO). This paper establishes a small-signal model of the VSC based multi-terminal direct current (VSC-MTDC) system with new energy access for the problem, and the influencing factors causing SSO are analyzed based on the eigen valueanalysis method. The theoretical analysis results show that the SSO in the system is related to the wind farm operating conditions, the rotor-side controller (RSC) of the DFIG and the interaction of the controller in the VSC-MTDC system. Then, the phase lag characteristicis obtained based on the signal test method, and a multi-channel variable-parameter subsynchronous damping controller (SSDC) is designed via selecting reasonable parameters.Finally, the correctness of the theoretical analysis and the effectiveness of the multi-channelvariable-parameter SSDC are verified based on time-domain simulation.

3

Dynamic interactions stability analysis of hybrid renewable energy system with SSSC

He Ping, Qi Pan, Ji Yuqi, Li Zhao

Archives of Electrical Engineering

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2021

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Vol. 70, nr 2

445--462

EN

The static series synchronous compensator (SSSC) has demonstrated its capability in providing voltage support and improving power system stability. The objective of this paper is to analyze the dynamic interaction stability mechanism of a hybrid renewable energy system connected with doubly-fed induction generators (DFIGs) and solid oxide fuel cell (SOFC) energy with the SSSC. For this purpose, a linearized mathematical model of this modified hybrid single-machine infinite-bus (SMIB) power system is developed to analyze the physical mechanism of the SSSC in suppressing oscillations and the influence on the dynamic stability characteristics of synchronization. Typical impacting factors such as the series compensation level, the SOFC penetration and tie-line power are considered in the SMIB and two-area systems. The impact of dynamic interactions on enhancing damping characteristics and improving transient performance of the studied systems is demonstrated using eigenvalue analysis and dynamic time-domain simulations, which validates the validity of the proposed physical mechanism simultaneously.