scholarly journals Advanced Fault Ride-through Strategy by an MMC HVDC Transmission for Off-Shore Wind Farm Interconnection

2019 ◽  
Vol 9 (12) ◽  
pp. 2522
Author(s):  
Lee ◽  
Yoo ◽  
Yoon ◽  
Jang

In order to solve the problems brought upon by off-shore wind-power plants, it is important to improve fault ride-through capability when an on-shore fault occurs in order to prevent DC overvoltage. In this paper, a coordinated control strategy is implemented for a doubly-fed induction generator (DFIG)-based off-shore wind farm, which connects to on-shore land by a modular multilevel converter (MMC)-based high voltage direct current (HVDC) transmission system during an on-shore fault. The proposed control strategy adjusts the DC voltage of the off-shore converter to ride through fault condition, simultaneously varying off-shore AC frequency. The grid-side converter detects the frequency difference, and the rotor-side converter curtails the output power of the DFIG. The surplus energy will be accumulated at the rotor by accelerating the rotor speed and DC link by rising DC voltage. By the time the fault ends, energy stored in the rotor and energy stored in the DC capacitor will be released to the on-shore side to restore the normal transmission state. Based on the control strategy, the off-shore wind farm will ride through an on-shore fault with minimum rotor stress. To verify the validity of the proposed control strategy, a DFIG-based wind farm connecting to the on-shore side by an MMC HVDC system is simulated by PSCAD with an on-shore Point of Common Coupling side fault scenario.

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7685
Author(s):  
Xiangwu Yan ◽  
Wenfei Chang ◽  
Sen Cui ◽  
Aazim Rassol ◽  
Jiaoxin Jia ◽  
...  

A large-scale power system breakdown in the United Kingdom caused blackouts in several important cities, losing about 3.2 percent of the load and affecting nearly 1 million power users on 9 August 2019. On the basis of the accident investigation report provided by the UK National Grid, the specific reasons for the sub-synchronous oscillation of Hornsea wind farm were analyzed. The Hornsea wind power system model was established by MATLAB simulation software to reproduce the accident. To solve this problem, based on the positive and negative sequence decomposition, the control strategy of grid-side converter of doubly-fed induction generator is improved to control the positive sequence voltage of the generator terminal, which can quickly recover the voltage by compensating the reactive power at the grid side. Consequently, the influence of the fault is weakened on the Hornsea wind farm system, and the sub-synchronous oscillation of the system is suppressed. The simulation results verify the effectiveness of the proposed control strategy in suppressing the sub-synchronous oscillation of weak AC wind power system after being applied to doubly-fed induction generator, which serves as a reference for studying similar problems of offshore wind power.


2021 ◽  
Vol 297 ◽  
pp. 01045
Author(s):  
Mohamed Amine Kazi ◽  
Radouane Majdoul ◽  
Nadia Machkour ◽  
Adnane El-alami ◽  
Ibrahim Baraka

The world is facing today the global challenge of energy transition since countries need more and more energy to grow their economy on a planet where resources are limited and poorly distributed. The integration of renewable energies and especially offshore wind energy into high voltage direct current (VSC-HVDC) transmission systems demonstrates great flexibility and reliability. In this paper, a control strategy for a multi-terminal VSC-HVDC system based on Master-Slave approach is proposed to automatically share the real power variation and stabilize the DC bus voltage in presence of abnormal operating conditions.


2017 ◽  
Vol 2017 (13) ◽  
pp. 1170-1175 ◽  
Author(s):  
Jinxin Ouyang ◽  
Mengyang Li ◽  
Ting Tang ◽  
Di Zheng ◽  
Rui Yu ◽  
...  

2015 ◽  
Vol 2015 ◽  
pp. 1-10
Author(s):  
Wen-ning Yan ◽  
Ke-jun Li ◽  
Zhuo-di Wang ◽  
Xin-han Meng ◽  
Jianguo Zhao

For the obvious advantages in integrating wind power, multiterminal HVDC transmission system (VSC-MTDC) is widely used. The priority control strategy is proposed in this paper considering the penetration rate of wind power for the AC grid. The strategy aims to solve the problems of power allocation and DC voltage control of the DC system. The main advantage of this strategy is that the demands for wind power of different areas can be satisfied and a power reference for the wind power trade can also be provided when wind farms transmit active power to several AC grids through the DC network. The objective is that power is well distributed according to the output power of wind farm with the demand of AC system and satisfactory control performance of DC voltage is obtained.


Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 380 ◽  
Author(s):  
Yingpei Liu ◽  
La Zhang ◽  
Haiping Liang

To solve the problems of DC voltage control and power allocation in the hybrid multi-terminal high voltage direct current system effectively, a DC voltage adaptive droop control strategy based on DC voltage-current characteristics is proposed. Based on adjustment of the droop coefficient of the converter station, the proposed control strategy introduces the influence factor of the droop coefficient, which considers the dynamic power margin of the converter station according to the direction of DC current variation in the converter station. When changes in the hybrid multi-terminal high voltage direct current system power flow occur, the droop coefficient of the converter station can be adjusted by the influence factor of the droop coefficient, so that the converter station can participate in power regulation according to its own power regulating ability. Consequently, the proposed control strategy can reasonably allocate the active power and minimize the deviation of the DC voltage. Besides, the stability analysis of the proposed control strategy is also carried out. Simulation results have verified the feasibility and effectiveness of the proposed control strategy.


Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 28 ◽  
Author(s):  
Bo Pang ◽  
Hui Dai ◽  
Feng Li ◽  
Heng Nian

For improving the performance of a doubly fed induction generator (DFIG) system under a harmonically distorted grid, this paper proposes a coordinated control strategy which is effective for grid inter-harmonics as well as grid integer harmonics. In order to suppress the negative impacts caused by grid harmonics, including inter-harmonics, this paper introduces an additional harmonics suppression controller, which contains a Chebyshev high-pass filter and a modified lead element considering the delay compensation. The proposed controller is employed in the rotor side converter (RSC) and grid side converter (GSC). Based on the proposed harmonics suppression controller, a coordinated control strategy between RSC and GSC is developed, in which the control targets, including the sinusoidal output current, constant power, or steady generator torque, can be achieved for DFIG, while GSC is responsible for maintaining the sinusoidal total current to guarantee the power quality of the grid connection. The effectiveness of the proposed method is verified by the theoretical analysis, and the experimental results derived using a 1 kW DFIG system validate the correctness of the theoretical analysis.


2013 ◽  
Vol 3 (2) ◽  
Author(s):  
Guo-Jie Li ◽  
Si-Ye Ruan ◽  
Tek Lie

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.


2021 ◽  
Vol 233 ◽  
pp. 01025
Author(s):  
Yingfeng Zhu ◽  
Xiaosu Xie ◽  
Dong Yang ◽  
Song Gao ◽  
Weichao Zhang ◽  
...  

Doubly fed induction generator (DFIG) wind power generation system is widely used in wind farm all over the world. Reactive power can be generated both in grid-side converter and generator-side converter of DFIG. In this paper, working principle and control method of DFIG are introduced, and the reactive power limit of DFIG is derived, finally reactive power regulation is simulated in Simulink.


Author(s):  
Congshan Li ◽  
Pu Zhong ◽  
Ping He ◽  
Yan Liu ◽  
Yan Fang ◽  
...  

: Two VSC-MTDC control strategies with different combinations of controllers are proposed to eliminate transient fluctuations in the DC voltage stability, resulting from a power imbalance in a VSC-MTDC connected to wind farms. First, an analysis is performed of a topological model of a VSC converter station and a VSC-MTDC, as well as of a mathematical model of a wind turbine. Then, the principles and characteristics of DC voltage slope control, constant active power control, and inner loop current control used in the VSC-MTDC are introduced. Finally, the PSCAD/EMTDC platform is used to establish an electromagnetic transient model of a wind farm connected to a parallel three-terminal VSC-HVDC. An analysis is performed for three cases of single-phase grounding faults on the rectifier and inverter sides of a converter station and of the withdrawal of the converter station on the rectifier side. Next, the fault response characteristics of VSC-MTDC are compared and analyzed. The simulation results verify the effectiveness of the two control strategies, both of which enable the system to maintain DC voltage stability and active power balance in the event of a fault. Background: The use of a VSC-MTDC to connect wind power to the grid has attracted considerable attention in recent years. A suitable VSC-MTDC control method can enable the stable operation of a power grid. Objective: The study aims to eliminate transient fluctuations in the DC voltage stability resulting from a power imbalance in a VSC-MTDC connected to a wind farm. Method: First, the topological structure and a model of a three-terminal VSC-HVDC system connected to wind farms are studied. Second, an analysis is performed of the outer loop DC voltage slope control, constant active power control and inner loop current control of the converter station of a VSC-MTDC. Two different control strategies are proposed for the parallel three-terminal VSC-HVDC system: the first is DC voltage slope control for the rectifier station and constant active power control for the inverter station, and the second is DC voltage slope control for the inverter station and constant active power for the rectifier station. Finally, a parallel three-terminal VSC-HVDC model is built based on the PSCAD/EMTDC platform and used to verify the accuracy and effectiveness of the proposed control strategy. Results: The results of simulation analysis of the faults on the rectifier and inverter sides of the system show that both strategies can restore the system to the stable operation. The effectiveness of the proposed control strategy is thus verified. Conclusion: The control strategy proposed in this paper provides a technical reference for designing a VSC-MTDC system for wind farms.


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