Evaluation Transient Stability of Large Scale Power System with Multi-Terminal HVDC

This paper presents the method of evaluating transient stability of large scale power system equipped with multi-terminal high voltage direct current (MTDC). The power system including synchronous machine, transmission network, and HVDC is based on the concepts of stability mode. In addition, various techniques to reduce the simulation time are systematically applied. The proposed method helps us to access the transient stability of the system with MTDC in the much simpler way. The verification of the methods is tested on 20 generators in an IEEE 118-bus system under various cases.

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Calculating the Interface Flow Limits for the Expanded Use of High-Voltage Direct Current in Power Systems

Energies ◽

10.3390/en13112863 ◽

2020 ◽

Vol 13 (11) ◽

pp. 2863

Author(s):

Sangwook Han

Keyword(s):

Power System ◽

High Voltage ◽

Direct Current ◽

Limit Analysis ◽

Large Scale ◽

Power Transmission ◽

Metropolitan Areas ◽

High Voltage Direct Current ◽

Flow Limit ◽

Current Lines

Although loads are increasingly becoming concentrated in metropolitan areas, power generation has decreased in metropolitan areas and increased in nonmetropolitan areas; hence, power transmission must occur through interface lines. To achieve this, additional transmission lines must be secured because the existing interface lines have reached their large-scale power transmission limits. The Korea Electric Power Corporation has installed many high-voltage direct current lines, thereby impacting the determination of interface power flow limits. These serve as the basis for system operations. However, knowledge of operating high-voltage direct current lines as a simple transmission line in a single power system is lacking. The effects of high-voltage direct current and its related parameters for interface flow limit analysis remain unclear. Furthermore, whether high-voltage direct current should be included in the selection of the interface lines that serve as the basis for interface flow remains unclear. In addition, whether the high-voltage direct current line faults should be included in the contingency list for determining the interface flow limits has not been considered. Additionally, it has not been determined whether to operate the DC tap when performing the simulation This study addresses these issues and determines the conditions that are necessary for determining the interface flow limits when a high-voltage direct current transmission facility has been installed in a land power system. The results conclude how to reflect the above conditions reasonably when performing the interface flow limit analysis on a system that includes the HVDC lines.

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Electromechanical Transient Modeling of Line Commutated Converter-Modular Multilevel Converter-Based Hybrid Multi-Terminal High Voltage Direct Current Transmission Systems

Energies ◽

10.3390/en11082102 ◽

2018 ◽

Vol 11 (8) ◽

pp. 2102 ◽

Cited By ~ 9

Author(s):

Liang Xiao ◽

Yan Li ◽

Huangqing Xiao ◽

Zheren Zhang ◽

Zheng Xu

Keyword(s):

High Voltage ◽

Direct Current ◽

Power Flow ◽

Large Scale ◽

Transient Stability ◽

Modular Multilevel Converter ◽

Multilevel Converter ◽

Hvdc System ◽

High Voltage Direct Current ◽

Current Transmission

A method for electromechanical modeling of line commutated converter (LCC)-modular multilevel converter (MMC)-based hybrid multi-terminal High Voltage Direct Current Transmission (HVDC) systems for large-scale power system transient stability study is proposed. Firstly, the general idea of modeling the LCC-MMC hybrid multi-terminal HVDC system is presented, then the AC-side and DC-side models of the LCC/MMC are established. Different from the conventional first-order DC-side model of the MMC, an improved second-order DC-side model of the MMC is established. Besides considering the firing angle limit of the LCC, a sequential power flow algorithm is proposed for the initialization of LCC-MMC hybrid multi-terminal HVDC system. Lastly, simulations of small scale and large scale power systems embedded with a three-terminal LCC-MMC hybrid HVDC system are performed on the electromechanical simulation platform PSS/E. It is demonstrated that if the firing angle limit is not considered, the accuracy of the power flow solutions will be greatly affected. Steady state calculation and dynamic simulation show that the developed LCC-MMC hybrid MTDC model is accurate enough for electromechanical transient stability studies of large-scale AC/DC system.

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Analysis of Subsynchronous Torsional of Wind–Thermal Bundled System Transmitted via HVDC Based on Signal Injection Method

Energies ◽

10.3390/en14020474 ◽

2021 ◽

Vol 14 (2) ◽

pp. 474

Author(s):

Junxi Wang ◽

Qi Jia ◽

Gangui Yan ◽

Kan Liu ◽

Dan Wang

Keyword(s):

Wind Power ◽

High Voltage ◽

Direct Current ◽

Computer Aided Design ◽

Large Scale ◽

Electromagnetic Transients ◽

Torsional Mode ◽

High Voltage Direct Current ◽

Operation Conditions ◽

Signal Injection

With the development of large-scale new energy, the wind–thermal bundled system transmitted via high-voltage direct current (HVDC) has become the main method to solve the problem of wind power consumption. At the same time, the problem of subsynchronous oscillation among wind power generators, high-voltage direct current (HVDC), and synchronous generators (SGs) has become increasingly prominent. According to the dynamic interaction among doubly fed induction generators (DFIGs), HVDC, and SGs, a linearization model of DFIGs and SGs transmitted via HVDC is established, and the influence of the electromagnetic transient of wind turbines and HVDC on the electromechanical transient processes of SGs is studied. Using the method of additional excitation signal injection, the influence of the main factors of DFIG on the damping characteristics of each torsional mode of SG is analyzed, including control parameters and operation conditions when the capacity of HVDC is fixed. The mechanism of the negative damping torsional of SGs is identified. A time-domain simulation model is built in Electromagnetic Transients including DC/Power Systems Computer Aided Design (EMTDC/PSCAD) to verify the correctness and effectiveness of the theoretical analysis.

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