A novel method for electromagnetic torque calculation applying positive and negative sequence current vectors

2016 ◽  
Vol 51 (4) ◽  
pp. 391-403 ◽  
Author(s):  
Pin Lv ◽  
Baojun Ge ◽  
Dajun Tao ◽  
Jiwei Yin ◽  
Hongsen Zhao
Keyword(s):  
Electromagnetic Torque ◽  
Negative Sequence ◽  
Novel Method ◽  
Negative Sequence Current

scholarly journals Turn-to-Turn Fault Diagnosis on Three-Phase Power Transformer Using Hybrid Detection Algorithm

2021 ◽  
Vol 11 (6) ◽  
pp. 2608
Author(s):  
Chien-Hsun Liu ◽  
Willybrordus H. P. Muda ◽  
Cheng-Chien Kuo
Keyword(s):  
Fuzzy System ◽  
Power Transformer ◽  
Detection Algorithm ◽  
Current Response ◽  
Negative Sequence ◽  
Three Phase ◽  
Hybrid Detection ◽  
Incipient Faults ◽  
Increase In Accuracy ◽  
Negative Sequence Current

A power transformer (PT) in power generation or transmission is critical to maintaining electrical continuity. Fault detection on a PT is needed, especially of incipient faults, which are often caused by a turn-to-turn fault (TTF) before it develops into a more severe fault. We use a hybrid algorithm between conventional and modern techniques to detect a developing fault in a PT. The current response signals from a negative sequence current directional algorithm, extended park vector algorithm (EPVA), differential negative sequence current, and EPVA-fuzzy system are combined to distinguish the possibility of a TTF. The subalgorithms are combined using a hybrid detection algorithm to distinguish the faults. The model is a 10 MVA, three-phase PT with Δ-Y configuration 150/300 kV, simulated using MATLAB Simulink software. The results show that by combining the subalgorithms, several limitations are distinguished within the TTF with a slight increase in accuracy.

scholarly journals A New Protection Strategy Based on Negative Sequence Current Coordinated Control on the Generator Extremity

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 135329-135338
Author(s):  
Zhenxing Li ◽  
Zhihao Xie ◽  
Zhenyu Wang ◽  
Hanli Weng ◽  
Lu Wang
Keyword(s):  
Coordinated Control ◽  
Negative Sequence ◽  
Protection Strategy ◽  
Negative Sequence Current

scholarly journals Non-Directional Earth Fault Passage Indication in Isolated Neutral Distribution Networks

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4732
Author(s):  
Amir Farughian ◽  
Lauri Kumpulainen ◽  
Kimmo Kauhaniemi
Keyword(s):  
Single Phase ◽  
Distribution Networks ◽  
Voltage Measurement ◽  
Negative Sequence ◽  
Overhead Lines ◽  
New Methods ◽  
Zero Sequence ◽  
Isolated Neutral ◽  
Negative Sequence Current ◽  
Symmetrical Sequence

In this paper, two new methods for locating single-phase to ground faults in isolated neutral distribution networks are proposed. The methods are based on the analysis of symmetrical sequence currents. They are solely based on currents, not requiring voltage measurement. The first method employs only the zero sequence current and the second one utilizes the negative sequence current in combination with the zero sequence current. It is revealed why using only zero sequence current with a simple threshold is insufficient and may lead to false results. Using the proposed methods, earth faults with high resistances can be located in isolated neutral distribution networks with overhead lines or cables.

scholarly journals A Comprehensive VSM Control Strategy Designed for Unbalanced Grids

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1169 ◽  
Author(s):  
Huiyu Miao ◽  
Fei Mei ◽  
Yun Yang ◽  
Hongfei Chen ◽  
Jianyong Zheng
Keyword(s):  
Control Strategy ◽  
Current Source ◽  
Synchronous Machine ◽  
Normal Operation ◽  
Complex Coefficient ◽  
Negative Sequence ◽  
Grid Voltage ◽  
Power Oscillations ◽  
Negative Sequence Current ◽  
Virtual Synchronous Machine

A virtual synchronous machine (VSM) is a converter which, compared to other types of converters, has more friendly interactions with the power grid because it is able to simulate the external characteristics of a synchronous machine, which can provide virtual inertia and damping. When the grid voltage is unbalanced, there will be negative sequence current and power oscillations. There will also be double-frequency ripples on the DC bus, which affect the normal operation of the DC power source or load. In order to solve these problems, a comprehensive control strategy is proposed in this paper. The principle of a VSM operated as a current source converter, also called VISMA, is used in the design. A complex coefficient filter is applied to separate the positive and negative sequence components of the grid voltage. By analyzing the reasons of power oscillations under unbalanced voltage, the electrical simulation part of the VSM is improved to achieve several objectives: to suppress negative sequence current and DC voltage ripples. Additionally, the rated voltage in the reactive control part is adaptively adjusted to stabilize the system. The validity of the proposed control strategy is verified by simulation and experiment.

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