scholarly journals Modeling and Stability Analysis of a Novel Voltage-Oriented Power Coordination Controlled Constant-Frequency AC Microgrid System

Electronics ◽  
2021 ◽  
Vol 10 (16) ◽  
pp. 1935
Author(s):  
Xiuhui Tang ◽  
Daming Zhang ◽  
Dan Xiao ◽  
Miao Li
Keyword(s):  
Stability Analysis ◽  
Power Distribution ◽  
Reactive Power ◽  
Mutual Influence ◽  
Constant Frequency ◽  
Model Stability ◽  
Power Regulation ◽  
The Stability ◽  
Grid Side ◽  
Ac Microgrid

The conventional AC microgrid power regulation method is achieved using dual undulations of the grid-side voltage and frequency, whose complex variables and processes make the system less efficient and stable. For this problem, this paper proposes a novel two-hierarchical small signal model stability analysis for islanded AC microgrid systems with a designed power regulation algorithm under the constant frequency, mainly aimed at the continual switching microgrids, and considers the future expansion. MATLAB/Simulink simulations and experiments are conducted to validate the feasibility. It is found that there is a strong consistency between the stability of primary and overall systems, and that two key parameters affect the stability properties. Discussing the mutual influence of various parameters, k1 is positively correlated with control intensity and k2 determines the proportion of reactive power distribution in each power generation. Contrasting with the previous complex processes, the unique points of this method are the simplicity of calculation, parameter induction, response testability, strong operability, and system extensibility. The conclusion is that this constant frequency power control is simple, feasible, and stable under several specified conditions.

scholarly journals Сombined ships stability analysis at the stage of design study

2021 ◽  
pp. 29-35
Author(s):  
Ilya A. Gulyaev Gulyaev ◽  
Evgeniy P. Ronnov
Keyword(s):  
Stability Analysis ◽  
Optimization Problems ◽  
Mutual Influence ◽  
Static Stability ◽  
Wind Effect ◽  
Stability Assessment ◽  
Design Study ◽  
Hull Design ◽  
The Stability ◽  
Russian River

. A method of stability analysis for combined ship (oil carrier/platform ship type) at the stage of design study is presented. It should be noted that not all of ship’s main seaworthiness and operational characteristics are the result of a simple addition of the characteristics of an oil carrier and a platform ship. Their mutual influence takes place, which should be taken into account when analysing the stability in the multivariant optimization problems of internal and external design of such ships. This leads to the requirement to adjust the known methods of stability analysis at the initial stages of ship design, which was the purpose of the present work and its originality. Taking into account the multivariance of the task and the hull design type, the stability assessment will be carried out through the analysis of the metacentric height extreme value on the assumption that the requirements of Russian River Register for admissible heeling angle at static wind effect are met. In order to account for nonlinearity of static stability curve when inclining up to the angles of deck immersion into water and emergence of bilge, it is suggested to apply an approximate method of metacentric radius determination. The proposed method of combined ship stability assessment is recommended to apply at the stage of justification and analysis of ship’s key elements as a limitation in the problems of mathematical modeling of optimization of such type of ships. The method allows to exclude from further consideration at the design study stage the possible options that do not meet the requirements of seaworthiness.

scholarly journals Simulation of reactive power regulation of DFIG

2021 ◽  
Vol 233 ◽  
pp. 01025
Author(s):  
Yingfeng Zhu ◽  
Xiaosu Xie ◽  
Dong Yang ◽  
Song Gao ◽  
Weichao Zhang ◽  
...  
Keyword(s):  
Wind Farm ◽  
Reactive Power ◽  
Control Method ◽  
Power Regulation ◽  
Working Principle ◽  
Power Limit ◽  
Doubly Fed ◽  
Grid Side ◽  
Grid Side Converter ◽  
And Control

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.

scholarly journals Impedance Aggregation Method of Multiple Wind Turbines and Accuracy Analysis

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2035 ◽  
Author(s):  
Liang Chen ◽  
Heng Nian ◽  
Yunyang Xu
Keyword(s):  
Stability Analysis ◽  
Reference Frame ◽  
Wind Turbines ◽  
Power Distribution ◽  
Wind Farm ◽  
System Level ◽  
Small Signal ◽  
Impedance Model ◽  
The Stability ◽  
The Impact

The sequence domain impedance modeling of wind turbines (WTs) has been widely used in the stability analysis between WTs and weak grids with high line impedance. An aggregated impedance model of the wind farm is required in the system-level analysis. However, directly aggregating WT small-signal impedance models will lead to an inaccurate aggregated impedance model due to the mismatch of reference frame definitions among different WT subsystems, which may lead to inaccuracy in the stability analysis. In this paper, we analyze the impacts of the reference frame mismatch between a local small-signal impedance model and a global one on the accuracy of aggregated impedance and the accuracy of impedance-based stability analysis. The results revealed that the impact is related to the power distribution of the studied network. It was found that that the influence of mismatch on stability analysis became subtle when subsystems were balanced loaded. Considering that balanced loading is a common configuration of the practical application, direct impedance aggregation by local small-signal models can be applied due to its acceptable accuracy.

Study on Stability and Reactive Power Optimization of Active Distribution Network Based on Bifurcation Theory

2015 ◽  
Vol 734 ◽  
pp. 701-706
Author(s):  
Xian Bin Dai
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Nonlinear Dynamic ◽  
Bifurcation Theory ◽  
Reactive Power ◽  
Distribution Network ◽  
Nonlinear Dynamic System ◽  
Reactive Power Optimization ◽  
Power Distribution Network ◽  
The Stability

as the basic method used to analyze the stability of nonlinear dynamic system, it is able to more deeply discuss the stability problems of power system in the vicinity of a critical point in comparison with traditional analysis method. Active power distribution network is a complicated nonlinear dynamic system. The change of voltage stability is the process to convert from stable status to bifurcation in essence. Taking 10-node active distribution system as an example, the author studies the influence of reactive power optimization on voltage stability based on bifurcation theory. The author explains the reactive optimization algorithm based on numerical simulation, namely, it is the decision - making algorithm in order to realize multiple purposes of having minimum power network loss, largest reactive power margin with stable operation of power distribution network and minimum voltage floating in system fluctuation, which is proved to be effective in elevating power distribution system stability, reducing power loss and improving voltage quality.

Static Characteristics Analysis for Induction Motors

2014 ◽  
Vol 1070-1072 ◽  
pp. 1191-1195
Author(s):  
Ying Jun Wu
Keyword(s):  
Stability Analysis ◽  
Induction Motor ◽  
Reactive Power ◽  
Induction Motors ◽  
Active Power ◽  
Static Characteristics ◽  
Voltage Curve ◽  
Characteristics Analysis ◽  
The Stability

This paper analyzes the static characteristics of induction motor. The models, as well as typical parameters, of induction motors for stability analysis are introduced. The slip-voltage curve, active power-voltage curve, and reactive power-voltage curve are obtained for analyzing possible operating states. According to the number and the stability of operating states, induction motors are classified to three kinds.

Control Strategy of the Charging-Discharging-Storage Integrated Station on Reactive Power/Voltage of Power System

2013 ◽  
Vol 860-863 ◽  
pp. 1120-1128 ◽  
Author(s):  
Yu Cheng Lou ◽  
Da Xie ◽  
Jun Qi Feng ◽  
Min Xia Yang ◽  
Yu Zhang
Keyword(s):  
Power System ◽  
Control Strategy ◽  
Power Distribution ◽  
Reactive Power ◽  
Value Added ◽  
Compensation Control ◽  
Standard Operation ◽  
Power Regulation ◽  
Operation Procedure ◽  
Added Benefit

Compared to reactive power/voltage index and standard operation procedure (SOP) of power system, the reactive power/voltage index of charging-discharging-storage integrated station is defined, which includes voltage margin and voltage adjustable capability of integrated station ((ISVM & ISVAC). And then the reactive power compensation control strategy of integrated station is put forward and proved to be lossless in power. According to the reactive power regulation characteristic, a reasonable reactive power distribution between shunt integrated stations can be realized by the reactive power/voltage optimization algorithm. And the synthesis optimization can be achieved when AVC applied into integrated station, which will bring value-added benefit to power quality and greatly improve the grid reliability.

scholarly journals Modeling and Analysis of 12-Pulse Inverter in Shipboard or Aircraft

2017 ◽  
Vol 24 (s3) ◽  
pp. 136-142
Author(s):  
Yanbo Che ◽  
Guojian Liu ◽  
Jianmei Xu ◽  
Yuancheng Zhao
Keyword(s):  
Stability Analysis ◽  
Power System ◽  
State Space ◽  
Distribution System ◽  
Mode Conversion ◽  
Operating Mode ◽  
Constant Frequency ◽  
Fast Analysis ◽  
Modeling And Analysis ◽  
The Stability

Abstract With the development of DC distribution system within the isolated power system of a ship or an aircraft, more constant frequency loads will be supplied by inverters connected to DC main bus. In the operating mode conversion process of an isolated power system, inverters will inevitably suffer from serious disturbance and affect the stability of the system. Therefore, it is important to establish a model of the inverter that reflects its dynamic characteristics and based on which to conduct the stability analysis. This paper proposes a 12-pulse inverter model based on the generalized state space averaging (GSSA) method. This model can overcome the limitations of 12-pulse inverter state space averaging (SSA) model in transient analysis with good accuracy and fast analysis ability effectively. Three kinds of models for a 12-pulse aircraft inverter are built in MATLAB, namely GSSA model, SSA model and detail device model. The simulation results show the high accuracy of GSSA model in stability analysis. This study provides an effective analytical tool for stability analysis of 12-pulse inverter and also provides a reference for inverter modeling research of isolated power system such as in aircraft or ship.

Improving the efficiency of oilfield electric power distribution

2019 ◽  
pp. 79-87
Author(s):  
Yu. F. Yu. F. Romaniuk ◽  
О. V. Solomchak ◽  
М. V. Hlozhyk
Keyword(s):  
Power Distribution ◽  
Reactive Power ◽  
Power Transmission ◽  
Transmission Efficiency ◽  
Active Power ◽  
Oil Field ◽  
Total Power ◽  
Simultaneous Increase ◽  
Active Load ◽  
Step Down

The issues of increasing the efficiency of electricity transmission to consumers with different nature of their load are considered. The dependence of the efficiency of the electric network of the oil field, consisting of a power line and a step-down transformer, on the total load power at various ratios between the active and reactive components of the power is analyzed, and the conditions under which the maximum transmission efficiency can be ensured are determined. It is shown by examples that the power transmission efficiency depends not only on the active load, but also largely on its reactive load. In the presence of a constant reactive load and an increase in active load, the total power increases and the power transmission efficiency decreases. In the low-load mode, the schedule for changing the power transmission efficiency approaches a parabolic form, since the influence of the active load on the amount of active power loss decreases, and their value will mainly depend on reactive load, which remains unchanged. The efficiency reaches its maximum value provided that the active and reactive components of the power are equal. In the case of a different ratio between them, the efficiency decreases. With a simultaneous increase in active and reactive loads and a constant value of the power factor, the power transmission efficiency is significantly reduced due to an increase in losses. With a constant active load and an increase in reactive load, efficiency of power transmission decreases, since with an increase in reactive load, losses of active power increase, while the active power remains unchanged. The second condition, under which the line efficiency will be maximum, is full compensation of reactive power.  Therefore, in order to increase the efficiency of power transmission, it is necessary to compensate for the reactive load, which can reduce the loss of electricity and the cost of its payment and improve the quality of electricity. Other methods are also proposed to increase the efficiency of power transmission by regulating the voltage level in the power center, reducing the equivalent resistance of the line wires, optimizing the loading of the transformers of the step-down substations and ensuring the economic modes of their operation.

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