scholarly journals Performance improvement of decentralized control for bidirectional converters in a DC micro-grid

2021 ◽  
Vol 12 (3) ◽  
pp. 1505
Author(s):  
Seyed Mojtaba Abbasi ◽  
Mehdi Nafar ◽  
Mohsen Simab
Keyword(s):  
Power Converters ◽  
Reactive Power ◽  
Genetic Optimization ◽  
Neural Controller ◽  
Bidirectional Converters ◽  
Controller Performance ◽  
Voltage Frequency ◽  
Grid Algorithm ◽  
Micro Grid ◽  
Genetic Optimization Algorithm

In this paper, using a neural controller and a genetic optimization algorithm to control the voltage as well as, control the frequency of the grid along with the management of the reactive power of the micro-grid to control the output power during islanding using Simultaneous bilateral power converters with voltage/frequency droop strategy and optimization of PI coefficients of parallel power converters by genetic-neural micro-grid algorithm to suppress AC side-current flow that increases stability and improvement of conditions frequency and voltage are discussed. Given the performance of the micro-grid in two simulation scenarios, namely transition from on-grid to off-grid, the occurrence of a step change in load in island mode as well as return to working mode is connected. The ability to detect the robust performance and proper performance of two-level neural controller. The controller performance time was also very good, indicating the appropriate features of the method used to design the controller, namely two-level neural, genetics. The main advantage of this method is its simplicity of design. The method used is also efficient and resistant to changes in the system, which results from the simulations.

scholarly journals A Novel Method of Optimal Capacitor Placement in the Presence of Harmonics for Power Distribution Network Using NSGA-II Multi-Objective Genetic Optimization Algorithm

2020 ◽  
Vol 25 (1) ◽  
pp. 17
Author(s):  
Majid Ebrahimi Moghadam ◽  
Hamid Falaghi ◽  
Mahdi Farhadi
Keyword(s):  
Optimization Algorithm ◽  
Reactive Power ◽  
Reducing Power ◽  
Optimal Placement ◽  
Genetic Optimization ◽  
Nonlinear Loads ◽  
Nsga Ii ◽  
Multi Objective ◽  
Capacitor Banks ◽  
Genetic Optimization Algorithm

One of the effective ways of reducing power system losses is local compensation of part of the reactive power consumption by deploying shunt capacitor banks. Since the capacitor’s impedance is frequency-dependent and it is possible to generate resonances at harmonic frequencies, it is important to provide an efficient method for the placement of capacitor banks in the presence of nonlinear loads which are the main cause of harmonic generation. This paper proposes a solution for a multi-objective optimization problem to address the optimal placement of capacitor banks in the presence of nonlinear loads, and it establishes a reasonable reconciliation between costs, along with improvement of harmonic distortion and a voltage index. In this paper, while using the harmonic power flow method to calculate the electrical quantities of the grid in terms of harmonic effects, the non-dominated sorting genetic (NSGA)-II multi-objective genetic optimization algorithm was used to obtain a set of solutions named the Pareto front for the problem. To evaluate the effectiveness of the proposed method, the problem was tested for an IEEE 18-bus system. The results were compared with the methods used in eight other studies. The simulation results show the considerable efficiency and superiority of the proposed flexible method over other methods.

scholarly journals Predictive control of multilevel converters for megawatt wind energy conversion systems

2021 ◽  
Author(s):  
Venkata Narasimha Rao Yaramasu
Keyword(s):  
Predictive Control ◽  
Power Converters ◽  
Reactive Power ◽  
Switching Frequency ◽  
Multilevel Converters ◽  
Wind Energy Conversion ◽  
Wind Energy Conversion Systems ◽  
Energy Conversion Systems ◽  
Bus Voltage ◽  
Grid Side

This dissertation proposes two novel medium voltage (MV) multilevel converter configurations for use with permanent magnet synchronous generator (PMSG) based megawatt (MW) wind energy conversion systems (WECS). The classical control techniques, based on linear PI regulators and low band-width modulation, present several technical issues during lower switching frequency operation. To overcome these issues, a high performance finite control-set model predictive control (FCS-MPC) strategy is proposed to control the power converters employed in the MW-PMSG-WECS. The proposed three-level and four-level converters combine the advantages of proven wind turbine technologies, such as low-cost generator-side passive converters, and efficient gridside multilevel converters. The intermediate dc-dc multilevel converters ensure balancing of the capacitor voltages during all operating conditions. With this feature, the grid-side multilevel converters produce better grid current waveforms compared to the back-to-back connected converters. A generalized approach for the predictive control of an n-level diode-clamped converter was investigated. The FCS-MPC strategy for current control and decoupled active/reactive power regulation of grid-connected multilevel converters was also analyzed. The major WECS requirements such as maximum power point tracking, balancing of dc-link capacitor voltages, switching frequency minimization, common-mode voltage mitigation, regulation of net dc-bus voltage, and grid reactive power control have been modeled in terms of power converter switching states. These control objectives have been accomplished during each sampling interval by selecting the switching states which minimize the generator- and grid-side cost functions. Issues related to the weighting factors selection, control delay compensation, accurate extrapolation of references, control of variable switching frequency nature, prediction of variables over two samples with reduced computational burden, and robustness analysis, are also addressed in this dissertation. To keep the dc-bus voltage constant during low voltage ride-through operation, predictive control scheme is proposed for the power converters while storing surplus energy in the turbine-generator rotor inertia. The generation and exchange of reference control variables during symmetrical grid voltage dips is suggested to meet the grid code requirements. The proposed solution is efficient as no energy is dissipated in the dc-link crowbar. The simulation and experimental results validate the proposed MV converters and predictive control schemes.

scholarly journals Investigating the impacts of the SVCs and the SCs affecting to the transient stability in multi-machine power system

2016 ◽  
Vol 19 (2) ◽  
pp. 16-24
Author(s):  
Quang Huu Vinh Luu
Keyword(s):  
Power System ◽  
Transient Stability ◽  
Reactive Power ◽  
Voltage Regulation ◽  
State Variables ◽  
Static Var Compensators ◽  
Transient Energy ◽  
Voltage Frequency ◽  
Power Outputs ◽  
Synchronous Condensers

A new algorithm simulating the impacts of the VAR supporting devices such as the static var compensators (SVCs) and the synchronous condensers (SCs) under condition of symmetrical disturbances in multi-machine power system is mentioned. Some typical numerical examples are presented in this article. The comparisons of variation of the state parameters, such as the voltage, frequency, reactive power outputs and asynchronous torques…are simulated under condition of the action of the automatic voltage regulation systems of generators and of the VAR supporting devices. The transient energy margins are calculated and compared to assess the transient stability in multi-machine power system. Basing on this algorithm, the PC program uses the elements of the eigen-image matrix to bring the specific advantages for the simulation of the transient features of state variables.

scholarly journals Kinematic Design of a Seven-Bar Linkage with Optimized Centrodes for Pure-Rolling Cutting

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Biao Liu ◽  
Yali Ma ◽  
Delun Wang ◽  
Shaoping Bai ◽  
Yangyang Li ◽  
...  
Keyword(s):  
Optimal Solution ◽  
Genetic Optimization ◽  
Dimensional Synthesis ◽  
Cutting Mechanism ◽  
Pure Rolling ◽  
Moving Points ◽  
Novel Method ◽  
Design Requirements ◽  
Genetic Optimization Algorithm ◽  
Peak Value

A novel method for designing a seven-bar linkage based on the optimization of centrodes is presented in this paper. The proposed method is applied to the design of a pure-rolling cutting mechanism, wherein close interrelation between the contacting lines and centrodes of two pure-rolling bodies is formulated and the genetic optimization algorithm is adopted for the dimensional synthesis of the mechanism. The optimization is conducted to minimize the error between mechanism centrodes and the expected trajectories, subject to the design requirements of the opening distance, the maximum amount of overlap error, and peak value of shearing force. An optimal solution is obtained and the analysis results show that the horizontal slipping and standard deviation of the lowest moving points of the upper shear blade have been reduced by 78.0% and 80.1% and the peak value of shear stress decreases by 29%, which indicate better cutting performance and long service life.

Dynamic Analysis and Parametric Optimization of Telescopic Tubular Mast Applied on Solar Sail

2020 ◽  
Author(s):  
Chen-Yang Ji ◽  
Jin-Guo Liu ◽  
Chen-Chen Wu ◽  
Peng-Yuan Zhao ◽  
Ke-Li Chen
Keyword(s):  
Natural Frequency ◽  
Parametric Design ◽  
Solar Sail ◽  
Work Flow ◽  
Equivalent Model ◽  
Genetic Optimization ◽  
Design And Optimization ◽  
Development Cycle ◽  
Equivalent Load ◽  
Genetic Optimization Algorithm

Abstract The Telescopic Tubular Mast (TTM) has excellent performance and is widely used in aerospace. Reasonable parameter design and optimization can shorten development cycle and improve performance for TTM. This paper designed a TTM driven by the bistable carbon reeled composite boom. The equivalent model of the TTM is established and simulated, which can be used as ex-tending structure for the solar sail. The work flow of the solar sail with the TTM is introduced. The natural frequency of the equivalent model and the segmented model is solved respectively using ABAQUS. The TTM under six different load conditions is analyzed. The influence of different factors on the vibration characteristics of the TTM is analyzed and the sensitivity analysis is carried out. Parameters including stiffness, natural frequency, mass and extension ratio are optimized using the multi-objective genetic optimization algorithm. According to the optimization results, the prototype was processed, and the experiment was completed with the equivalent load of solar sail. It provides a reference for the parametric design of the TTM.

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