scholarly journals Ride-Through Control Method for the Continuous Commutation Failures of HVDC Systems Based on DC Emergency Power Control

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4183 ◽  
Author(s):  
Chao Xiao ◽  
Wei Han ◽  
Jinxin Ouyang ◽  
Xiaofu Xiong ◽  
Wei Wang
Keyword(s):  
Power Control ◽  
Direct Current ◽  
Control Method ◽  
Control Strategies ◽  
Equivalent Model ◽  
Emergency Control ◽  
Emergency Power ◽  
Ac Systems ◽  
The Stability ◽  
The Impact

Continuous commutation failures (CFs) are serious malfunctions in line-commutated converter high-voltage direct current (HVDC) systems that cause the continuous and rapid sag of transmitted power and may threaten the stability of AC systems. The conventional emergency control strategies of AC systems exhibit difficulty in responding quickly and accurately. After suffering from continuous CFs, the forced blocking of direct current (DC) converter to prevent AC system instability might also cause other adverse effects. This study proposes a ride-through control method to improve the endurance capability of AC systems against continuous CFs. An active power output model of inverter station under continuous CFs is built, while considering the process and mechanism of CFs. The impact of continuous DC power sag on the stability of sending-end system is analyzed through a four-area AC/DC equivalent model. A rolling calculation model for the power angle and acceleration area variations of the sending-end system during continuous CFs is established on the basis of model predictive control theory. A calculation method for the emergency power control reference is obtained by using the aforementioned models. Lastly, a ride-through control method for continuous CFs is developed by utilizing the emergency control of adjacent HVDC link. Simulation results show that the proposed control method can improve the endurance capability of an AC system to continuous CFs and reduce blocking risk in an HVDC link.

The stable transfer method using zero power control in the CTTS system

2019 ◽  
Vol 57 (4) ◽  
pp. 376-384 ◽  
Author(s):  
Ho-Yun Seon ◽  
Ji-Hoon Yang ◽  
Sang-Hun Lee ◽  
Seong-Mi Park ◽  
Sung-Jun Park
Keyword(s):  
Power Control ◽  
Power Supply ◽  
Current Flow ◽  
The State ◽  
Power Sources ◽  
Electrical Arc ◽  
Transfer Method ◽  
The Stability ◽  
The Impact ◽  
Grid Management

In the CTTS system, while transferring the power supply from the grid to the generator, a sudden arc arises, which causes damage to the system. The method proposed in this study reduces this damage. The power state of the generator stage is made equal to the state of the power of the grid in order to prevent the occurrence of a sudden arc. Even if the generator power state is the same with the power state of the generator, an arc can be generated due to a sudden current flow during the transfer. Therefore, the current in the generator stage is controlled to 0 (zero) when transferring, so that the generation of an electrical arc is minimized. In general, when the CTTS system is used for transferring power sources with an emergency generator, the impact from the electrical arc will be momentarily proportional to the amount of the power supplied from the generator to the load. The damage by the arc will make the life of the CTTS system shorter. In order to prevent such damage, a blocking technique using parallel capacitor is constituted. However, this causes arc generation at the time of input. Thus, in this paper, it is proposed to control the effective or ineffective power of the system to zero. To verify the validity of the proposed method, firstly the Powersim simulation was conducted, and after confirming the feasibility based on this, the actual prototype was created and implemented. Zero power control is proposed as a way to improve the stability of CTTS by significantly reducing the generation of an electrical arc. And this technique can help people working on the distributed power or the grid management.

Lattice hydrodynamic model-based feedback control method with traffic interruption probability

2019 ◽  
Vol 33 (23) ◽  
pp. 1950273 ◽  
Author(s):  
Cong Zhai ◽  
Weitiao Wu
Keyword(s):  
Feedback Control ◽  
Hydrodynamic Model ◽  
Traffic Congestion ◽  
Control Method ◽  
Feedback Controller ◽  
Lattice Hydrodynamic Model ◽  
Feedback Control Method ◽  
The Stability ◽  
Probability Effect ◽  
The Impact

Connected vehicles are expected to become commercially available by the next decade, while traffic interruption is not uncommon in the real traffic environment. In this paper, we propose a feedback control method for lattice hydrodynamic model considering the traffic interruption probability effect. The stability criterion of the new model is explored through linear stability analysis of transfer function. When the stability conditions are not satisfied, a delay feedback controller is used to control the discharging flow to suppress traffic congestion. The impact of gain coefficient and delay time on the performance is discussed. We verify the effectiveness of the devised delay feedback controller by simulations. Results show that the traffic interruption probability effect has a considerable impact on the stability of traffic flow, while the controller is effective in suppressing traffic congestion.

scholarly journals Research on Virtual Inductive Control Strategy for Direct Current Microgrid with Constant Power Loads

2019 ◽  
Vol 9 (20) ◽  
pp. 4449 ◽  
Author(s):  
Zhiping Cheng ◽  
Meng Gong ◽  
Jinfeng Gao ◽  
Zhongwen Li ◽  
Jikai Si
Keyword(s):  
Transmission Line ◽  
Direct Current ◽  
Control Strategy ◽  
Control Method ◽  
Control Strategies ◽  
Performance Comparison ◽  
Distributed Resources ◽  
Constant Power ◽  
Dc Microgrid ◽  
Constant Power Loads

In order to improve the stability of direct current (DC) microgrid with constant power loads, a novel virtual inductive approach is proposed in this paper. It is known that the negative impedance characteristic of constant power loads will lead to DC bus voltage fluctuation, which will be more serious when they integrate into the DC microgrid though a large transmission line inductive. For the convenience of analysis, a simplified circuit model of the system is obtained by modeling the distributed resources. Unlike the existing control strategies, the proposed control strategy constructs a negative inductance link, which helps to counteract the negative effects of the line inductive between the power source and the transmission line. Detailed performance comparison of the proposed control and virtual capacitance are implemented through MATLAB/simulink simulation. Moreover, the improved performance of the proposed control method has been further validated with several detailed studies. The results demonstrate the feasibility and superiority of the proposed strategy.

Microgrid Operation under Frequency Control Method

2014 ◽  
Vol 698 ◽  
pp. 716-721 ◽  
Author(s):  
D.V. Armeev ◽  
A.Y. Arestova ◽  
Y.A. Abramova
Keyword(s):  
Distribution System ◽  
Control Method ◽  
Control Strategies ◽  
Frequency Control ◽  
Load Shedding ◽  
Technical Problems ◽  
Emergency Control ◽  
Interconnected Power System ◽  
Control Actions ◽  
Intensive Development

Intensive development of cogeneration and SmartGrid technologies provide an opportunity to form Microgrid within a distribution system. Microgrid can act as part of an interconnected power system or operate in isolated mode. Islanding is performed under faults, power interruption, etc. There are several technical problems when Microgrid resynchronizes to the grid. This paper presents three control strategies to be used to reconnect with the utility: 1. without any emergency control actions; 2. frequency load shedding; 3. frequency control method.

An uplink power optimization solution for satellite HUBs station based on closed-loop control algorithm

2021 ◽  
pp. 28-36
Author(s):  
Do Xuan Quyet
Keyword(s):  
Power Control ◽  
Closed Loop ◽  
Satellite Communication ◽  
Power Optimization ◽  
Control Method ◽  
Control Device ◽  
Loop Control ◽  
Wave Path ◽  
Automatic Power Control ◽  
The Impact

In this paper, we present a power optimization solution based on the automatic power control method using a closed-loop algorithm for the uplink power control device (UPC) of the satellite communication HUB station. The results are evaluated by theoretical analysis and validated by simulation model on Matlab software, finally the model has also been used in the UPC device and tested in practice. The simulation process, and the test is carried out under the impact of varying rainfall on the wave path, the results are compared with the solutions that have been and are being used to demonstrate the effectiveness of the solution. This paper is the research product of the project "Researching, designing and manufacturing the uplink power controller military satellite communication system".

scholarly journals A Schistosomiasis Model with Mating Structure

2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Longxing Qi ◽  
Jing-an Cui
Keyword(s):  
Sex Ratio ◽  
Numerical Simulations ◽  
Latent Period ◽  
Control Strategies ◽  
Control Measure ◽  
Sensitivity Analyses ◽  
Threshold Condition ◽  
The Stability ◽  
Mating Function ◽  
The Impact

A schistosomiasis model is proposed including single schistosomes, paired schistosomes, snails, and the latent period of infected snails. A reasonable sex ratio of schistosomes and the minimum mating function are considered. A threshold condition determining the stability of the system is given, and the stability of equilibrium for the model is shown. The impact of the latent period of infected snails on schistosomiasis transmission can be found through numerical simulations. Finally, preferable control strategies are obtained by sensitivity analyses. Killing snails may be the preferred control measure. If we choose chemotherapy, we should use some drugs which are sufficient for reducing egg-associated pathology, since paired schistosomes are mostly harmful to definitive hosts.

scholarly journals Analysis of COVID-19 Prevention and Control Effects Based on the SEITRD Dynamic Model and Wuhan Epidemic Statistics

2020 ◽  
Vol 17 (24) ◽  
pp. 9309
Author(s):  
Yusheng Zhang ◽  
Liang Li ◽  
Yuewen Jiang ◽  
Biqing Huang
Keyword(s):  
Dynamic Model ◽  
Control Method ◽  
Control Strategies ◽  
Dynamical Behavior ◽  
Model Parameters ◽  
Time Control ◽  
Intervention Measures ◽  
Travel Restrictions ◽  
And Control ◽  
The Impact

Since December 2019, millions of people worldwide have been diagnosed with COVID-19, which has caused enormous losses. Given that there are currently no effective treatment or prevention drugs, most countries and regions mainly rely on quarantine and travel restrictions to prevent the spread of the epidemic. How to find proper prevention and treatment methods has been a hot topic of discussion. The key to the problem is to understand when these intervention measures are the best strategies for disease control and how they might affect disease dynamics. In this paper, we build a transmission dynamic model in combination with the transmission characteristics of COVID-19. We thoroughly study the dynamical behavior of the model and analyze how to determine the relevant parameters, and how the parameters influence the transmission process. Furthermore, we subsequently compare the impact of different control strategies on the epidemic, the variables include intervention time, control duration, control intensity, and other model parameters. Finally, we can find a better control method by comparing the results under different schemes and choose the proper preventive control strategy according to the actual epidemic stage and control objectives.

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