scholarly journals Vector Control of VSC HVDC System under Single Line to Ground Fault Condition

Author(s):  
Prabodha Kumar Rath ◽  
Kanhu Charan Bhuyan

<span lang="EN-US">This paper proposes a model of a VSC (voltage source converter) based Back to Back HVDC system and its control technique under fault condition. From the mathematical model of the system relationship between the controlling and the controlled variables is determined to control the system parameters. An appropriate vector control technique is used to control active and reactive power and to maintain DC link voltage. The proposed controlling unit consists of outer control loop and inner control loop which effectively damped out the system oscillation and maintains the system stability. The validity of the model and the feasibility of the control method have been proved by the simulation results. In this paper the system performance is studied under fault condition is studied.</span>

2013 ◽  
Vol 14 (2) ◽  
pp. 123-138
Author(s):  
Madhan Mohan ◽  
Bhim Singh ◽  
Bijaya Ketan Panigrahi

Abstract: A New Voltage Source Converter (VSC) based on neutral clamped three-level circuit is proposed for High Voltage DC (HVDC) system. The proposed VSC is designed in a multipulse configuration. The converter is operated by Fundamental Frequency Switching (FFS). A new control method is developed for achieving all the necessary control aspects of HVDC system such as independent real and reactive power control, bidirectional real and reactive power control. The basic of the control method is varying the pulse width and by keeping the dc link voltage constant. The steady state and dynamic performances of HVDC system interconnecting two different frequencies network are demonstrated for active and reactive power control. Total number of transformers used in this system are reduced to half in comparison with the two-level VSCs for both active and reactive power control. The performance of the HVDC system is improved in terms of reduced harmonics level even at fundamental frequency switching. The harmonic performance of the designed converter is also studied for different value of the dead angle (β), and the optimized range of the dead angle is achieved for varying reactive power requirement. Simulation results are presented for the designed three level multipulse voltage source converters with the proposed control algorithm.


Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3222
Author(s):  
Duc Nguyen Huu

Increasing offshore wind farms are rapidly installed and planned. However, this will pose a bottle neck challenge for long-distance transmission as well as inherent variation of their generating power outputs to the existing AC grid. VSC-HVDC links could be an effective and flexible method for this issue. With the growing use of voltage source converter high-voltage direct current (VSC-HVDC) technology, the hybrid VSC-HVDC and AC system will be a next-generation transmission network. This paper analyzes the contribution of the multi VSC-HVDC system on the AC voltage stability of the hybrid system. A key contribution of this research is proposing a novel adaptive control approach of the VSC-HVDC as a so-called dynamic reactive power booster to enhance the voltage stability of the AC system. The core idea is that the novel control system is automatically providing a reactive current based on dynamic frequency of the AC system to maximal AC voltage support. Based on the analysis, an adaptive control method applied to the multi VSC-HVDC system is proposed to realize maximum capacity of VSC for reactive power according to the change of the system frequency during severe faults of the AC grid. A representative hybrid AC-DC network based on Germany is developed. Detailed modeling of the hybrid AC-DC network and its proposed control is derived in PSCAD software. PSCAD simulation results and analysis verify the effective performance of this novel adaptive control of VSC-HVDC for voltage support. Thanks to this control scheme, the hybrid AC-DC network can avoid circumstances that lead to voltage instability.


Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2260
Author(s):  
Fan Cheng ◽  
Lijun Xie ◽  
Zhibing Wang

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.


Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2223 ◽  
Author(s):  
Haifeng Liang ◽  
Yue Dong ◽  
Yuxi Huang ◽  
Can Zheng ◽  
Peng Li

The stable operation of a microgrid is crucial to the integration of renewable energy sources. However, with the expansion of scale in electronic devices applied in the microgrid, the interaction between voltage source converters poses a great threat to system stability. In this paper, the model of a three-source microgrid with a multi master–slave control method in islanded mode is built first of all. Two sources out of three use droop control as the main control source, and another is a subordinate one with constant power control which is also known as real and reactive power (PQ) control. Then, the small signal decoupling control model and its stability discriminant equation are established combined with “virtual impedance”. To delve deeper into the interaction between converters, mutual influence of paralleled converters of two main control micro sources and their effect on system stability is explored from the perspective of control parameters. Finally, simulation and analysis are launched and the study serves as a reference for parameter setting of converters in a microgrid.


2014 ◽  
Vol 626 ◽  
pp. 184-189
Author(s):  
A.S. Monikandan ◽  
N. Kesavan Nair

The Interline Power Flow Controller (IPFC) is a voltage-source-converter (VSC)-based flexible ac transmission system (FACTS) controller for series compensation in a multiline transmission system of a substation. The capability of injecting series voltages with controllable magnitude and phase angle makes it a powerful tool for better utilization of existing transmission lines in a multiline transmission system. IPFC is used to regulate active and reactive power flow in a multiline system, usually. In this paper, a control method for IPFC is proposed to control magnitude and phase angle of one sending bus of a substation. All degrees of freedom of IPFC and decoupled synchronous frame concept are used in the proposed control structure. Simulation results in Matlab/Simulink are presented to show the capability of IPFC in compensating the bus voltage.


2021 ◽  
Vol 11 (13) ◽  
pp. 5847
Author(s):  
Xinglong Wu ◽  
Zheng Xu ◽  
Zheren Zhang

This paper analyzes the power stability of the hybrid dual-infeed high-voltage direct-current (HVDC) system containing a line commutated converter-based HVDC (LCC-HVDC) and a voltage source converter-based HVDC (VSC-HVDC). First, the concept and the calculation method of power stability for the hybrid dual-infeed HVDC system are introduced. Second, the influence of VSC-HVDC on the power stability of the system is investigated. Third, the relationship between the power stability and the effective short circuit ratio (ESCR) is discussed under different system parameters. Then, the value range of the critical effective short circuit ratio is determined. Finally, the evaluation criteria of power stability are proposed. The results show that the evaluation criteria of the single-infeed LCC-HVDC system can still be used, if the VSC-HVDC is in constant AC voltage control mode; if the VSC-HVDC is in constant reactive power control mode, the hybrid dual-infeed HVDC system cannot operate stably when the ESCR is less than 2.0 and can operate stably with high power stability margin when the ESCR is greater than 3.0. The ESCR index can still be used to measure the power stability of the hybrid dual-infeed HVDC system.


Author(s):  
Duli Chand Meena ◽  
◽  
Madhusudan Singh ◽  
Ashutosh K. Giri ◽  
◽  
...  

This paper dealt the implementation of a Leaky-Momentum Control Algorithm (LMA) for controlling a voltage source converter (VSC) to enhance the power quality of a three-phase self-excited induction generator (SEIG) used in a distributed generating system. This LMA technique operates the VSC to regulate voltage and frequency of SEIG within a permissible limit. The LMA control is implemented to reduce the higher demand of reactive power, harmonics distortions and balancing of loads under different operating conditions. During the electrical and mechanical dynamical conditions, the LMA technique is maintaining a constant voltage and frequency at point of common coupling (PCC). The proposed technique is a modified control technique of basic Leaky and Momentum Algorithms. This control has removed the drawbacks of Leaky and momentum algorithms. Moreover, it is observed that LMA performs better when there are uncertainties in input conditions. The whole system comprising SEIG, nonlinear load, voltage source converter and battery storage system is made in MATLAB /SIMULINK. It has shown promising performance under both dynamical state and steady state of the system.


Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 333 ◽  
Author(s):  
Chengjiang Hu ◽  
Yumei Ma ◽  
Jinpeng Yu ◽  
Lin Zhao

This paper studies the coordination control of active and reactive power of the voltage source converter-high voltage direct current transmission (VSC-HVDC) grid side converter. Firstly, the high-order VSC-HVDC converter system is decomposed into three subsystems by using the backstepping control method, and the control laws are designed for each subsystem to realize the control of VSC-HVDC converter systems. Secondly, the dynamic surface control method is used to deal with the problem of “explosion of complexity” in the traditional backstepping control method. Finally, the simulation results demonstrate that the VSC-HVDC converter systems can provide a certain capacity of reactive power compensation under the proposed method in this paper. In addition, the control method proposed in this paper does not require the information of the second derivative of active power and reactive power.


Electronics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 399
Author(s):  
Mahmuda Begum ◽  
Mohsen Eskandari ◽  
Mohammad Abuhilaleh ◽  
Li Li ◽  
Jianguo Zhu

This research suggests a novel distributed cooperative control methodology for a secondary controller in islanded microgrids (MGs). The proposed control technique not only brings back the frequency/voltage to its reference values, but also maintains precise active and reactive power-sharing among distributed generation (DG) units by means of a sparse communication system. Due to the dynamic behaviour of distributed secondary control (DSC), stability issues are a great concern for a networked MG. To address this issue, the stability analysis is undertaken systematically, utilizing the small-signal state-space linearized model of considering DSC loops and parameters. As the dynamic behaviour of DSC creates new oscillatory modes, an intelligent fuzzy logic-based parameter-tuner is proposed for enhancing the system stability. Accurate tuning of the DSC parameters can develop the functioning of the control system, which increases MG stability to a greater extent. Moreover, the performance of the offered control method is proved by conducting a widespread simulation considering several case scenarios in MATLAB/Simscape platform. The proposed control method addresses the dynamic nature of the MG by supporting the plug-and-play functionality, and working even in fault conditions. Finally, the convergence and comparison study of the offered control system is shown.


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