Fast recovery strategy for MMC-HVDC based on coordination of fault current suppression and adaptive restart

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jingru Zhang ◽  
Baina He ◽  
Qiurui Zhang ◽  
Xingmin He ◽  
Yanchen Dong ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Current System ◽  
Short Interval ◽  
Fault Current ◽  
Suppression Effect ◽  
High Voltage Direct Current ◽  
Single Function ◽  
Critical Problems ◽  
Restart Strategy ◽  
The Stability

Abstract The rapid suppression of fault current flowing through overhead transmission lines and safe restart of the system are critical problems to be solved urgently to improve the stability of the DC grid. A novel adaptive restart strategy combined with fault current suppression is proposed, which suitable for full-bridge modular multilevel converter high voltage direct current system. The resistance-capacitance energy transfer branch is used to achieve a large reduction and rapid attenuation of the fault current amplitude at restart time. The transient fault and permanent fault can be discriminated in a short interval after restarting based on the frequency domain amplitude characteristics. The proposed scheme has both restart-current protection and fault property identification functions, overcoming the high cost and low component reusability of traditional single-function fault current limiting schemes. The simulation results show that the scheme has a significant fault current suppression effect and accurately discriminates the fault property to realize rapid recovery.

CURRENT ISSUES OF INTERBUDGETARY EQUALIZATION

2020 ◽  
Vol 1 (12) ◽  
pp. 74-78
Author(s):  
A. A. BISULTANOVA ◽  
Keyword(s):  
Economic Policy ◽  
Economic Development ◽  
Russian Federation ◽  
Current System ◽  
Federal Budget ◽  
Financial Resources ◽  
Socio Economic Development ◽  
Interregional Differentiation ◽  
The Russian Federation ◽  
The Stability

The author touched upon topical issues of inter-budget alignment, budget provision of regions with financial resources, focusing on factors that directly affect the stability of the budget system, as well as highlighting problems in the budget sphere that require urgent attention from the authorities. It is concluded that the level of interregional differentiation continues to increase, and the modern mechanism of budget equalization requires urgent amendments and adjustments. It is emphasized that the main goals of socio-economic development of the Russian Federation related to the transition to an innovative type of development, changes in the structure of the national economy, set out in strategic documents and messages of the President of the Russian Federation and declared since 2009, are not being implemented, and the effectiveness of state economic policy and Federal budget expenditures for its implementation remains low. This indicates the need to review the current system.

Study on the characteristics of secondary arc current of UHV high compensation degree TCSC line under the fine-tuning mode

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Baina He ◽  
Yadi Xie ◽  
Jingru Zhang ◽  
Nirmal-Kumar C. Nair ◽  
Xingmin He ◽  
...  
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Stability Margin ◽  
Transmission Capacity ◽  
Fine Tuning ◽  
Series Compensation ◽  
Arc Current ◽  
Compensation Device ◽  
The Stability ◽  
Recovery Voltage

Abstract In the transmission line, the series compensation device is often used to improve the transmission capacity. However, when the fixed series capacitor (FSC) is used in high compensation series compensation device, the stability margin cannot meet the requirements. Therefore, thyristor controlled series compensator (TCSC) is often installed in transmission lines to improve the transmission capacity of the line and the stability of the system. For cost considerations, the hybrid compensation mode of FSC and TCSC is often adopted. However, when a single-phase grounding fault occurs in a transmission line with increased series compensation degree, the unreasonable distribution of FSC and TCSC will lead to the excessive amplitude of secondary arc current, which is not conducive to rapid arc extinguishing. To solve this problem, this paper is based on 1000 kV Changzhi-Nanyang-Jingmen UHV series compensation transmission system, using PSCAD simulation program to established UHV series compensation simulation model, The variation law of secondary arc current and recovery voltage during operation in fine tuning mode after adding TCSC to UHV transmission line is analyzed, and the effect of increasing series compensation degree on secondary arc current and recovery voltage characteristics is studied. And analyze the secondary arc current and recovery voltage when using different FSC and TCSC series compensation degree schemes, and get the most reasonable series compensation configuration scheme. The results show that TCSC compensation is more beneficial to arc extinguishing under the same series compensation. Compared with several series compensation schemes, it is found that with the increase of the proportion of TCSC, the amplitude of secondary arc current and recovery voltage vary greatly. Considering various factors, the scheme that is more conducive to accelerating arc extinguishing is chosen.

scholarly journals Galloping Stability and Wind Tunnel Test of Iced Quad Bundled Conductors considering Wake Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xiaohui Liu ◽  
Ming Zou ◽  
Chuan Wu ◽  
Mengqi Cai ◽  
Guangyun Min ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Transmission Lines ◽  
Degrees Of Freedom ◽  
Wind Tunnel Test ◽  
Aerodynamic Coefficients ◽  
Wake Effect ◽  
Aerodynamic Coefficient ◽  
Set Up ◽  
The Stability ◽  
Three Degrees Of Freedom

A new quad bundle conductor galloping model considering wake effect is proposed to solve the problem of different aerodynamic coefficients of each subconductor of iced quad bundle conductor. Based on the quasistatic theory, a new 3-DOF (three degrees of freedom) galloping model of iced quad bundle conductors is established, which can accurately reflect the energy transfer and galloping of quad bundle conductor in three directions. After a series of formula derivations, the conductor stability judgment formula is obtained. In the wind tunnel test, according to the actual engineering situation, different variables are set up to accurately simulate the galloping of iced quad bundle conductor under the wind, and the aerodynamic coefficient is obtained. Finally, according to the stability judgment formula of this paper, calculate the critical wind speed of conductor galloping through programming. The dates of wind tunnel test and calculation in this paper can be used in the antigalloping design of transmission lines.

scholarly journals The Way of Reducing Current Values in Optical Ground Wires at Asymmetrical Faults on Overhead Transmission Lines

2016 ◽  
Vol 11 (1) ◽  
pp. 13-20
Author(s):  
Georgiy Egamnazarov
Keyword(s):  
Cross Section ◽  
Transmission Lines ◽  
Conclusive Evidence ◽  
Fault Current ◽  
Overhead Lines ◽  
Optical Cable ◽  
Electric Power Grid ◽  
Three Phase ◽  
Wire Steel ◽  
Wire System

Abstract Given the fact that the installing costs of an optical ground wire on overhead lines directly depend on its cross-section, which in turn depends on the level of fault current it should withstand, in order to reduce these current values in the optical ground wire, I suggested performing its isolated descents from the end towers of the line with its transition to an optical cable. The research was carried out on the example of a 500 kV overhead line in the National Electric Power Grid. The Method of Symmetrical Components for calculating asymmetrical fault currents was not used; therefore, calculations were carried out on the base of presenting the line as a multi-wire system for the considered case as a five-wire system (optical ground wire, steel ground wire, and three phase wires). Such approach allows taking into account the initial asymmetry of the line parameters and modeling any kind of asymmetrical faults. The analyses of calculated results were performed. The conclusive evidence that the optical ground wire isolated descents from the end towers of the line give the possibility of reducing the level of maximal fault current distribution values in it and therefore its cross section, is presented.

scholarly journals Modelling of the Power Interface of the Digital-Physical Hybrid Simulation System of a VSC-HVDC Based on Virtual Resistance Compensation

Electronics ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 333
Author(s):  
Jian Le ◽  
Hao Zhang ◽  
Cao Wang ◽  
Xingrui Li ◽  
Jiangfeng Zhu
Keyword(s):  
Current Source ◽  
Hybrid Simulation ◽  
Simulation System ◽  
System Stability ◽  
Interface Model ◽  
Simulation Accuracy ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
The Stability ◽  
Stability And Accuracy

To enhance the stability and accuracy of the digital-physical hybrid simulation system of a modular multilevel converter-based high voltage direct current (MMC-HVDC) system, this paper presents an improved power interface modeling algorithm based on ideal transformer method (ITM). By analyzing the stability condition of a hybrid simulation system based on the ITM model, the current of a so-called virtual resistance is added to the control signal of the controlled current source in the digital subsystem, and the stability of the hybrid simulation system with the improved power interface model is analyzed. The value of the virtual resistance is optimized by comprehensively considering system stability and simulation precision. A two-terminal bipolar MMC-HVDC simulation system based on the proposed power interface model is established. The comparisons of the simulation results verify that the proposed method can effectively improve the stability of the hybrid simulation system, and at the same time has the advantages of high simulation accuracy and easy implementation.

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