scholarly journals Research on Voltage Stabilizing Control Strategy of Critical Load in Unplanned Island Based on Electric Spring

Electronics ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 80
Author(s):  
Hongjun Wang ◽  
Chunchao Song ◽  
Youjun Yue ◽  
Hui Zhao
Keyword(s):  
Critical Load ◽  
Control Strategy ◽  
Critical Loads ◽  
Control Mode ◽  
Experimental Simulation ◽  
Hybrid Microgrid ◽  
Stabilizing Control ◽  
Working Principle ◽  
Bus Voltage ◽  
The Stability

Aiming to solve the problem of voltage fluctuation of critical load caused by lack of control when an unplanned island occurs in a microgrid, a voltage stabilizing control strategy of critical load based on electric spring is proposed in this paper. When unplanned islanding occurs in a microgrid system, the system bus voltage fluctuates dramatically due to instantaneous power imbalance, compromising the power supply safety of important loads on the bus. In this paper, the electric spring control mode is integrated into the voltage stabilizing control strategy of critical loads in an unplanned island for the first time to realize the protection of critical loads. First of all, a model of an optical storage AC/DC hybrid microgrid is built, the overall system architecture is determined, and the microgrid is divided into four working states. Second, the working principle of electric spring is introduced, and a decoupling control strategy based on double closed loop is proposed. Finally, the experimental simulation of the proposed control strategy is experimentally simulated in Matlab/Simulink environment. The simulation findings show that when the bus voltage and current of microgrid change due to an unplanned island, the proposed control strategy based on electric spring may achieve the stability of voltage and current on critical loads.

Study on Grid-Injected System with Regenerative Braking Energy for Subway

2012 ◽  
Vol 516-517 ◽  
pp. 1437-1442
Author(s):  
Qiu Rui Zhang ◽  
Bao Ming Ge ◽  
Da Qiang Bi
Keyword(s):  
Temperature Rise ◽  
Control Strategy ◽  
Control Method ◽  
Design Procedure ◽  
Energy Utilization ◽  
Regenerative Braking ◽  
Resistance Heating ◽  
Urban Rail ◽  
Bus Voltage ◽  
The Stability

At present, the rate of energy utilization is low for the transit regenerative braking on urban rail; most of the energy is consumed by the resistance heating. In this paper, a regenerative braking energy injected-grid device is designed, which makes use of regenerative braking energy and effectively reduce the temperature rise caused by the resistance in the tunnel. The paper describes the composition and the design procedure of regenerative braking energy injected-grid device and presents a control strategy of device. The simulation of the single train model verifies that the stability of DC-bus voltage can be maintained and more power can be feedback to the grid by the proposed device when the train is braking. The feasibility and effectiveness of the proposed control method are validated by the experimental results.

The estimation of the critical load of a braced framework

1955 ◽  
Vol 231 (1184) ◽  
pp. 25-36 ◽  
Keyword(s):  
Critical Load ◽  
Critical Loads ◽  
The Other ◽  
Simple Criterion ◽  
Relaxation Methods ◽  
The Stability

With present methods of estimating the critical loads of triangulated frameworks by relaxation methods it is difficult to decide near the critical load whether the process is converging and the structure is stable, or whether the process is diverging and the structure unstable. This difficulty does not arise in the method presented here. Each triangle of the framework in turn is replaced by a hypothetical member until finally only one member of the truss remains, and this member has been modified in such a way as to take into account the stiffnesses of all the other members of the truss. A simple criterion for the stability of this final equivalent member is established and an example of the application of the method given.

CRITICAL LOADS OF SQUARE PLATES UNDER DIFFERENT INPLANE LOAD CONFIGURATIONS ON OPPOSITE EDGES

2001 ◽  
Vol 01 (02) ◽  
pp. 283-291 ◽  
Author(s):  
S. G. LEE ◽  
S. C. KIM ◽  
J. G. SONG
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stability Analysis ◽  
Critical Load ◽  
Critical Loads ◽  
Patch Load ◽  
Fixity Factor ◽  
The Stability ◽  
Opposite Tendency ◽  
Width Factor

The elastic critical load coefficients of square plates, under different inplane load configurations on opposite plate edges, are determined and the results compared. The stability analysis was performed by a finite element method that was developed by the authors. The parameters considered in the analysis are the Kinney's fixity factor, and the width factor of the patch load. It was found that the coefficients of the critical loads increase with increasing values of fixity and width factors. The opposite tendency is that a plate under a patch loaded towards the two corners of an edge is more stable than a plate loaded concentrically at the center of the edge.

scholarly journals Hierarchical and Droop Method for DC Micro-grid Bus Voltage under Isolated operation

2020 ◽  
Vol 185 ◽  
pp. 01062
Author(s):  
Xiangyang Yan ◽  
Ningkang Zheng ◽  
Yilong Kang ◽  
Huanruo Qi ◽  
Kai Li ◽  
...  
Keyword(s):  
Control Strategy ◽  
Power Supply ◽  
System Level ◽  
Level Control ◽  
New Energy ◽  
Operation Control ◽  
Micro Grid ◽  
Dc Bus ◽  
Bus Voltage ◽  
The Stability

Nowadays, distributed generation technology is of great help to the efficient utilization of new energy. If the distributed power supply is connected to the DC micro-grid, it will be more secure and reliable. Therefore, it is necessary to control the voltage stability of the DC bus and ensure the balance of the source charge power of system to ensure the power supply quality and safety of the DC micro-grid. There are two operation modes of DC micro-grid: connected operation and isolated operation, and isolated operation control is the foundation and key of system-level control of DC micro-grid. To solve the problem of bus voltage fluctuation in isolated dc micro-grid, this study proposes a voltage hierarchical-droop control strategy for DC micro-grid, which can effectively improve the stability of the DC bus voltage. Last, this study builds the simulation model of DC micro-grid in the MATLAB/Simulink platform to verify the validity and feasibility of the proposed control strategy.

Snapping of Low Pinned Arches on an Elastic Foundation

1973 ◽  
Vol 40 (3) ◽  
pp. 741-744 ◽  
Author(s):  
G. J. Simitses
Keyword(s):  
Critical Load ◽  
Elastic Foundation ◽  
Critical Loads ◽  
Entire Range ◽  
Buckling Load ◽  
Stability Studies ◽  
Deflection Curve ◽  
The Stability ◽  
Load Deflection Curve ◽  
Range Of Values

The problem of a low half-sine pinned arch under a quasi-statically applied half-sine load is considered. The low arch is resting on an elastic foundation. Critical loads are obtained by investigating the stability of the equilibrium positions by considering all possible modes of deformation. It is assumed that the behavior of the arch is linearly elastic up to the critical load. The entire range of values for the modulus of the foundation is considered. The results are presented graphically as either critical load (snap-through) or classical buckling load (stable bifurcation) versus the rise parameters for a large number of values of the modulus of foundations. This investigation presents an interesting model for stability studies, because, depending on the value of the rise parameter and the modulus of the foundation, the load-deflection curve exhibits the possibilities of the top-of-the-knee buckling, snap-through buckling through unstable bifurcation, and classical buckling (stable bifurcation).

The Approximate Elastic Critical Loads of Continuous Struts

1962 ◽  
Vol 66 (622) ◽  
pp. 652-654
Author(s):  
H. Waters
Keyword(s):  
Critical Load ◽  
Critical Loads ◽  
Axial Load ◽  
Simultaneous Equations ◽  
The Stability

The determination of the critical axial load of a strut having one or more intermediate supports and varying stiffness is made difficult by the highly transcendental nature of the simultaneous equations involved. It is therefore usual to make a test of the stability of the strut at some arbitrarily chosen load, as for example when applying the convergence technique. The behaviour of the strut then indicates whether the chosen load is too high or too low, and another load is selected and another test made. Although the true critical load is eventually reached, it is clear that if its value can be fairly closely approximated at the outset, then the labour of calculation will be greatly reduced.

A Control Strategy for a Series APF With Critical-Load-Bus Voltage Feedback That Avoids Injection Transformer Saturation

2019 ◽  
Vol 55 (3) ◽  
pp. 2290-2299
Author(s):  
Guilherme da Silva Fischer ◽  
Alisson Mengatto ◽  
Luis Gustavo Kremer ◽  
Marcello Mezaroba
Keyword(s):  
Critical Load ◽  
Control Strategy ◽  
Bus Voltage ◽  
Voltage Feedback

scholarly journals Research on power control strategy of household-level electric power router based on hybrid energy storage droop control

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Kun Huang ◽  
Yanman Li ◽  
Xiaoyan Zhang ◽  
Lei Liu ◽  
Yanbin Zhu ◽  
...  
Keyword(s):  
Power Control ◽  
Control Strategy ◽  
Control Unit ◽  
Stable Operation ◽  
Droop Control ◽  
Hybrid Energy ◽  
Household Level ◽  
Dc Bus ◽  
Bus Voltage ◽  
The Stability

AbstractIn the light of user-side energy power control requirements, a power control strategy for a household-level EPR based on HES droop control is proposed, focusing on the on-grid, off-grid and seamless switching process. The system operating states are divided based on the DC bus voltage information with one converter used as a slack terminal to stabilize the DC bus voltage and the other converters as power terminals. In the on-grid mode, the GCC and the HES are used as the main control unit to achieve on-grid stable operation, whereas in the off-grid mode, the PV, HES and LC are used as the main control unit at different voltages to achieve stable operation of the island network. Finally, a DC MG system based on a household-level EPR is developed using the PSCAD / EMTDC simulation platform and the results show that the control strategy can effectively adjust the output of each subunit and maintain the stability of the DC bus voltage.

Towards a new design with generic modeling and adaptive control of a transformable quadrotor

2021 ◽  
pp. 1-31
Author(s):  
S.H. Derrouaoui ◽  
Y. Bouzid ◽  
M. Guiatni
Keyword(s):  
Adaptive Control ◽  
Control Strategy ◽  
Experimental Tests ◽  
Generic Model ◽  
System Control ◽  
System A ◽  
Viable Solution ◽  
Generic Modeling ◽  
Adaptive Control Strategy ◽  
The Stability

Abstract Recently, transformable Unmanned Aerial Vehicles (UAVs) have become a subject of great interest in the field of flying systems, due to their maneuverability, agility and morphological capacities. They can be used for specific missions and in more congested spaces. Moreover, this novel class of UAVs is considered as a viable solution for providing flying robots with specific and versatile functionalities. In this paper, we propose (i) a new design of a transformable quadrotor with (ii) generic modeling and (iii) adaptive control strategy. The proposed UAV is able to change its flight configuration by rotating its four arms independently around a central body, thanks to its adaptive geometry. To simplify and lighten the prototype, a simple mechanism with a light mechanical structure is proposed. Since the Center of Gravity (CoG) of the UAV moves according to the desired morphology of the system, a variation of the inertia and the allocation matrix occurs instantly. These dynamics parameters play an important role in the system control and its stability, representing a key difference compared with the classic quadrotor. Thus, a new generic model is developed, taking into account all these variations together with aerodynamic effects. To validate this model and ensure the stability of the designed UAV, an adaptive backstepping control strategy based on the change in the flight configuration is applied. MATLAB simulations are provided to evaluate and illustrate the performance and efficiency of the proposed controller. Finally, some experimental tests are presented.

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