scholarly journals A Method of Demarcating Critical Failure Impedance Boundary of Multi-Infeed HVDC Systems Based on Minimum Extinction Angle

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Song Zhang ◽  
Guoqing Li ◽  
Shuguang Li ◽  
Xintong Liu
Keyword(s):  
Impedance Boundary ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
Extinction Angle ◽  
Double Phase ◽  
Interaction Factor ◽  
Three Phase ◽  
Calculation Results ◽  
Nodal Voltage ◽  
Bus System

A method of rapidly demarcating the critical commutation failure (CF) region of a multi-infeed high-voltage direct-current (HVDC) system is proposed. Based on the nodal impedance matrix and nodal voltage interaction factor, for different AC fault conditions—both balanced and unbalanced—a method of calculating the extinction angles of converters in multi-infeed HVDC systems is deduced in detail. First, the extinction angles of convertor stations under single-phase, double-phase, and three-phase ground faults and line-to-line faults occurring at any bus in an AC system are calculated. The minimum extinction angle serves as a CF criterion. If the calculated extinction angle for a certain bus is smaller than the minimum extinction angle, then a fault at that bus will cause CF of the HVDC system and put that bus into a failed bus set. The critical failure impedance boundaries of the topology diagram can therefore be demarcated by examining every bus in the AC system. The validity and accuracy of the proposed index and the method were verified by calculation results based on the three-infeed HVDC system model of the IEEE 39-bus system. Finally, the critical failure impedance boundary was demarcated in the IEEE 118-bus system to demonstrate the application in a wider range of systems.

scholarly journals Determining Region Boundaries of Critical Commutation Failures in Multi-Infeed HVDC Systems Under Unbalanced Short Circuit Faults

2021 ◽  
Vol 9 ◽  
Author(s):  
Guoqing Li ◽  
Song Zhang ◽  
Shuguang Li ◽  
Xianchao Liu ◽  
Xintong Liu
Keyword(s):  
High Voltage ◽  
Direct Current ◽  
Short Circuit ◽  
Impedance Matrix ◽  
Determination Method ◽  
High Voltage Direct Current ◽  
Extinction Angle ◽  
Bus System

This paper presents a region boundaries determination method for critical commutation failures (CF) in multi-infeed high-voltage direct-current (HVDC) systems under unbalanced short circuit faults. By using the nodal impedance matrix, a calculation approach for the converter extinction angles is deduced. First, the extinction angles under unbalanced short circuit faults are calculated. If the extinction angle of a bus is less than the minimum extinction angle, the bus is a failed bus set. By this means, region boundaries of critical commutation failures are demarcated by examining each bus in the AC system. Finally, the effectiveness of the proposed approach was verified by using a modified IEEE 39-bus system.

Real power regulation design for multi-terminal VSC-HVDC systems

2013 ◽  
Vol 3 (2) ◽  
Author(s):  
Guo-Jie Li ◽  
Si-Ye Ruan ◽  
Tek Lie
Keyword(s):  
Control Strategy ◽  
Control Mode ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Real Power ◽  
The Real ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
Power Regulation ◽  
Regulation Functions

AbstractA multi-terminal voltage-source-converter (VSC) based high voltage direct current (HVDC) system is concerned for its flexibility and reliability. In this study, a control strategy for multiple VSCs is proposed to auto-share the real power variation without changing control mode, which is based on “dc voltage droop” power regulation functions. With the proposed power regulation design, the multiple VSCs automatically share the real power change and the VSC-HVDC system is stable even under loss of any one converter while there is no overloading for any individual converter. Simulation results show that it is effective to balance real power for power disturbance and thus improves operation reliability for the multi-terminal VSC-HVDC system by the proposed control strategy.

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.

scholarly journals Multi-Pulse SCR Rectifiers

2021 ◽  
Author(s):  
Mei Li
Keyword(s):  
Experimental Verification ◽  
Current Source ◽  
Harmonic Distortion ◽  
Motor Drives ◽  
Line Current ◽  
High Voltage Direct Current ◽  
Battery Chargers ◽  
Power Battery ◽  
Harmonic Elimination ◽  
Three Phase

This thesis presents the introduction, analysis and experimental verification of the six-pulse SCR rectifier and multi-pulse SCR rectifiers. As a fundamental three-phase controllable ac-dc converter, the six-pulse SCR rectifier is widely used in industry. However, it generates high Total Harmonic Distortion (THD) in the line current. One of the solutions is to use multi-pulse rectifiers. Multi-pulse rectifiers could be classified into the 12-, 18-, and 24-pulse configurations. Application examples include high voltage direct current transmission systems, high power battery chargers and load commutated current source inverter powered motor drives. In this thesis, the six-, 12-, 18- and 24-pulse SCR rectifiers with inductive and capacitive loads are introduced. The line current THD and the input PF of various rectifiers are investigated. The principle of the harmonic elimination through phase-shifting transforms is analyzed by Fourer analysis and positive/negative sequence analysis. The experimental verification is accomplished on a prototype of the 12-pulse SCR recitifier.

scholarly journals Research on the Voltage Interaction of Multi-Infeed HVDC System and Interaction Factor

2015 ◽  
Vol 03 (04) ◽  
pp. 41-48
Author(s):  
Shengjun Zhou ◽  
Guangyao Qiao ◽  
Chuan He ◽  
Wenhui Wang ◽  
Tianqi Liu
Keyword(s):  
Hvdc System ◽  
Interaction Factor

Decoupled AC/DC Power Flow Strategy for Multiterminal HVDC Systems

2018 ◽  
Vol 19 (1) ◽  
Author(s):  
Yixiang Gao ◽  
Shuhui Li ◽  
Weizhen Dong ◽  
Bing Lu
Keyword(s):  
Power Flow ◽  
Control Mode ◽  
Power Flow Calculation ◽  
Flow Calculation ◽  
Power System Control ◽  
Flow Method ◽  
Hvdc System ◽  
Dc Power ◽  
Bus System ◽  
Power Flow Method

AbstractThis paper proposes a decoupled AC/DC power flow approach for multi-terminal HVDC systems. The proposed method simplifies the power flow computation of multi-terminal HVDC systems while accurately reflecting the operation and control characteristics of VSC (voltage source converter) stations in a HVDC network. In the DC network, the power flow calculation is conducted based on a slack DC bus VSC station and power commends issued to other VSC stations from the power system control center. Then, in the AC power flow calculation, VSC stations are treated as special AC generators that can generate and absorb power from the AC grid in active and reactive power or active power and bus voltage control mode. For validation purpose, the conventional unified power flow method for multi-terminal HVDC systems is built. The paper compares the proposed method with the unified power flow method for an 8-bus multi-terminal HVDC system based on MATPOWER. Then, more case studies for different VSC control modes are conducted and evaluated for the 8-bus system. Afterwards, the proposed method is applied to the power flow study of a more practical and complicated multi-terminal HVDC system based on the IEEE 118-bus system.

scholarly journals Research on Serial VSC-LCC Hybrid HVdc Control Strategy and Filter Design Scheme

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2260
Author(s):  
Fan Cheng ◽  
Lijun Xie ◽  
Zhibing Wang
Keyword(s):  
Reactive Power ◽  
Filter Design ◽  
Control Strategies ◽  
Short Circuit ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Level Control ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
Design Scheme

This paper investigated the characteristics of a novel type of hybrid high voltage direct current (HVdc) converter, which is composed by line commutated converter series with voltage source converter. The system and valve level control strategies are introduced, which can provide ac system voltage support. A novel filter design scheme composed by resonant filers for hybrid HVdc are also proposed, which can decrease the capacity of reactive power compensation equipment without deteriorate harmonic characteristics. The ac voltage of HVdc fluctuation level caused by transmitted power variation will be effectively reduced, with the coordination between filter design scheme and converter control. In addition, the influence of ac grid strength is also analyzed by equivalent source internal impedance represented by short circuit ratio (SCR). Finally, the +800 kV/1600 MW hybrid HVdc system connecting two ac grids under different SCR cases are studied, and the PSCAD/EMTDC simulation results have validated the effectiveness for proposed strategy.

scholarly journals Minimum Short Circuit Ratio Requirement for MMC-HVDC Systems Based on Small-Signal Stability Analysis

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3283 ◽  
Author(s):  
Zheren Zhang ◽  
Liang Xiao ◽  
Guoteng Wang ◽  
Jian Yang ◽  
Zheng Xu
Keyword(s):  
Reactive Power ◽  
Short Circuit ◽  
Small Signal ◽  
Small Signal Stability ◽  
Ratio Requirement ◽  
Planning Stage ◽  
Hvdc System ◽  
Hvdc Transmission ◽  
High Voltage Direct Current ◽  
Signal Stability

This paper determines the minimum short circuit ratio (SCR) requirement for a modular multilevel converter based high-voltage direct current (MMC-HVDC) transmission systems. Firstly, a simplified model of MMC is introduced; the MMC is represented by its AC and DC side equivalent circuit. Next, by linearizing the MMC subsystem and the DC network subsystem, the deduction of the small-signal models of MMC subsystem, the small-signal model of the DC network and MMC-HVDC are carried out successively. Thirdly, the procedure for determining the minimum SCR requirement of MMC-HVDC is described. Finally, case studies are performed on a two-terminal MMC-HVDC system under four typical control schemes. The results show that the restraint factors for the rectifier MMC is predominantly the voltage safety limit constraint, and the restraint factors for the inverter MMC are mainly the phase locked loop (PLL) or the outer reactive power controller. It is suggested that the minimum SCR requirement for the sending and the receiving systems should be 2.0 and 1.5 in the planning stage.

scholarly journals A Selective Fault Clearing Scheme for a Hybrid VSC-LCC Multi-Terminal HVdc System

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3554
Author(s):  
Naushath M. Haleem ◽  
Athula D. Rajapakse ◽  
Aniruddha M. Gole ◽  
Ioni T. Fernando
Keyword(s):  
High Capacity ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Circuit Breakers ◽  
Hvdc System ◽  
Hvdc Transmission ◽  
High Voltage Direct Current ◽  
Clearing Functions ◽  
Transmission Structure ◽  
The Impact

A selective fault clearing scheme is proposed for a hybrid voltage source converter (VSC)-line commutated converter (LCC) multi-terminal high voltage direct current (HVdc) transmission structure in which two small capacity VSC stations tap into the main transmission line of a high capacity LCC-HVdc link. The use of dc circuit breakers (dc CBs) on the branches connecting to VSCs at the tapping points is explored to minimize the impact of tapping on the reliability of the main LCC link. This arrangement allows clearing of temporary faults on the main LCC line as usual by force retardation of the LCC rectifier. The faults on the branches connecting to VSC stations can be cleared by blocking insulated gate bipolar transistors (IGBTs) and opening ac circuit breakers (ac CB), without affecting the main line’s performance. A local voltage and current measurement based fault discrimination scheme is developed to identify the faulted sections and pole(s), and trigger appropriate fault recovery functions. This fault discrimination scheme is capable of detecting and discriminating short circuits and high resistances faults in any branch well before 2 ms. For the test grid considered, 6 kA, 2 ms dc CBs can easily facilitate the intended fault clearing functions and maintain the power transfer through healthy pole during single-pole faults.

An Application Seven-Level Converter for VSC-HVDC Station System

2015 ◽  
Vol 799-800 ◽  
pp. 1211-1216
Author(s):  
Narin Watanakul
Keyword(s):  
Process Control ◽  
Control Algorithm ◽  
Current Control ◽  
Multilevel Converter ◽  
Two Phase ◽  
Hvdc System ◽  
Hvdc Transmission ◽  
Data Process ◽  
Three Phase ◽  
Level Converter

This paper presents an application of an asynchronous back to back VSC-HVDC system. Which uses multilevel converter a 7-level Diode-Clamped SPWM converters topology technique for the realization of HVDC system, rated 300MVA (±300 kV). The controller has been proposed by using PQ control and feed-forward decoupled current control algorithm. The design and experimentally controllers of VSC in lab scaled test, MATLAB/Simulink program were performed VSC-HVDC transmission system, the simulation in order to evaluate transient performance, can be controlled independently under two phase to ground faulted and three phase to ground faulted conditions. The system are used as a guideline for analysing and design of the data process control with the PQ-control HVDC system.

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