scholarly journals Decoupled Current Controller Based on Reduced Order Generalized Integrator for Three-Phase Grid-Connected VSCs in Distributed System

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2426 ◽  
Author(s):  
Sen Zhang ◽  
Jianfeng Zhao ◽  
Zhihong Zhao ◽  
Kangli Liu ◽  
Pengyu Wang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Design Method ◽  
Reference Signal ◽  
Response Speed ◽  
Critical Issue ◽  
Voltage Source ◽  
Current Loop ◽  
Reduced Order ◽  
Distributed Power Generation ◽  
Current Controller

Grid-connected voltage source converters (GC-VSCs) are used for interfacing the distributed power generation system (DPGS) to the utility grid. Performance of the current loop is a critical issue for these GC-VSCs. Recently, reduced order generalized integrator (ROGI)-based current controller is proposed, such that AC reference signal of positive or negative sequences can be separately tracked without steady-state error, which has the advantage of less computational burden. However, the cross-coupling within the ROGI-based current controller would deteriorate the transient response of the current loop. In this paper, a ROGI-based decoupled current controller is proposed to eliminate the coupling between α -axis and β -axis. Thus, the faster dynamic response performance can be achieved while maintaining the merits of ROGI-based current controller. An optimal gain parameter design method for the proposed current controller is presented to improve the stability and dynamic response speed of current loop. Simulation and experiments were performed in MATLAB/Simulink and TMS320C28346 DSP-based laboratory prototype respectively, which validated the proposed theoretical approach.

scholarly journals A Double Update PWM Method to Improve Robustness for the Deadbeat Current Controller in Three-Phase Grid-Connected System

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Ling Yang ◽  
Yandong Chen ◽  
An Luo ◽  
Kunshan Huai ◽  
Leming Zhou ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Characteristic Root ◽  
Response Speed ◽  
Current Control ◽  
System Stability ◽  
Grid Current ◽  
Current Controller ◽  
Three Phase ◽  
Grid Connected Inverter ◽  
Deviation Coefficient

In the grid-connected inverter based on the deadbeat current control, the filter inductance variation and single update PWM affect the distortion of the grid current, stability, and dynamic of the system. For this, a double update PWM method for the deadbeat current controller in three-phase grid-connected system is proposed, which not only effectively decreases the grid current distortion and control delay, but also improves the system stability and dynamic response speed due to reducing the characteristic root equation order of the closed-loop transfer function. The influence of the filter inductance deviation coefficient on the system performance is analyzed. As a conclusion, the corresponding filter inductance deviation coefficient in the system critical stability increases with increase in the parasitic resistance of the filter inductance and line equivalent resistance and decreases with increase in the sampling frequency. Considering the system stability and dynamic response, the optimal range of the control parameters is acquired. Simulation and experimental results verify the effectiveness of the proposed method.

scholarly journals Department of Electrical Power and Machine Engineering, Faculty of Engineering,

2021 ◽  
pp. 46-72
Author(s):  
حمدى محمد سليمان
Keyword(s):  
Dynamic Response ◽  
Permanent Magnet ◽  
Control Method ◽  
Permanent Magnet Synchronous Motor ◽  
Synchronous Motor ◽  
Voltage Source ◽  
Conventional Model ◽  
Current Controller ◽  
Three Phase ◽  
Torque Ripples

This paper aims to reduce the torque ripples in the motor torque, reduce the total harmonics distortion in the motor currents and improve the dynamic response of the permanent magnet synchronous motor. To carry out this study, a modification model was used and compared to conventional model. The main control method used here is a field-oriented control. It was used to generate two decoupled currents control. With help of rotor position, these currents changing into three-phase reference currents. These reference currents were compared to the actual three-phase motor currents. The errors among these currents are introduced to hysteresis current controller to get pulses. These pulses used to drive the voltage source inverter which produces three-phase voltage to drive the motor under study. This technique suffers from some problems as high torque ripples, high total harmonics distortion, the dynamic response isn’t very high because at the beginning of the error and the deviation of the output signal becomes large. This is a conventional model. To overcome these problems, the hysteresis current controller was replaced by gain impedance. The output of this gain is the three-phase voltages. These voltages generate pulses through space vector modulation to drive the inverter to get suitable voltage for the permanent magnet synchronous motor. This modification has decreased the torque ripples and the THD in comparison to the conventional controller. To more improvement in the motor performance, one PI torque current controller and load torque estimator were used to damp the overshooting and decrease the rise time.

scholarly journals Modeling and Parameter Design of Voltage-Controlled Inverters Based on Discrete Control

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2154 ◽  
Author(s):  
Ningbo Dong ◽  
Huan Yang ◽  
Junfei Han ◽  
Rongxiang Zhao
Keyword(s):  
Design Method ◽  
Dynamic Performance ◽  
Resonance Peak ◽  
Design Flow ◽  
Discrete Control ◽  
Current Loop ◽  
Current Controller ◽  
Voltage Controller ◽  
The Stability ◽  
The Mathematical Model

Grid-connected inverters are widely used to interface renewable energy and energy storage resources into the grid. Voltage-controlled inverters have attracted more and more attention due to their grid-friendly characteristics. The mathematical models of the voltage and current loops are developed in this paper, considering especially the discrete control delay caused by calculation and modulation. In order to suppress the resonance peak in the current loop, the frequency characteristics of the current loop are analyzed in detail. The optimum design flow of the current controller and voltage controller parameters are presented based on numerical analysis, and the stability, dynamic performance and the resonance peak suppression in voltage loop are also considered. Finally, the validity of the mathematical model and the effectiveness of the controller parameters design method are verified by simulation and experimental results.

Control Strategy for Voltage Source Converter-Based HVDC System under Unbalanced Voltage Conditions

2013 ◽  
Vol 437 ◽  
pp. 629-633 ◽  
Author(s):  
Ming Guang Zhang ◽  
Diao Bing Wang ◽  
Zhong Kuan Zhang
Keyword(s):  
Control Strategy ◽  
Vector Current ◽  
Response Speed ◽  
Simulation Software ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Hvdc System ◽  
Dual Vector ◽  
Current Controller ◽  
Unbalanced Voltage

The mathematical model of voltage source converter-based flexible DC transmission system (VSC-HVDC) and traditional fault control strategy are comprehensively analyzed. The proportional resonant controller in the traditional dual vector current controller is proposed to simplify the structure of traditional inner current controller. The proposed method improves the response speed and control accuracy of the control system. According to the output voltage distortion caused by the DC voltage ripple, the PWM with amplitude-adjustable carrier is adopted, and according to the DC side voltage rise the power setting value is adjusted. Finally, the control strategy is verified by the electromagnetic transient simulation software PSCAD/EMTDC, the simulation results show it can effectively restrain the fault overvoltage, improve the operation ability of the system.

Optimum Design of Journal Bearings Dimensions for Rotating Machines

2020 ◽  
Vol 38 (10A) ◽  
pp. 1481-1488
Author(s):  
Tariq M. Hammza ◽  
Ehab N. Abas ◽  
Nassear R. Hmoad
Keyword(s):  
Aspect Ratio ◽  
Dynamic Response ◽  
Numerical Solution ◽  
Critical Speed ◽  
Design Method ◽  
Considerable Effect ◽  
Journal Bearings ◽  
Rotating Machines ◽  
Bearing Clearance ◽  
Study Results

The values of Many parameters which involve in the design of fluid film journal bearings mainly depend on the bearing applied load when using the conventional design method to design the journal bearings, in this study, as well as applied bearing load, the dynamic response and critical speed have been used to calculate the dimensions of journal bearings. In the field of rotating machine, especially a heavy-duty rotating machines, the critical speed and response are the main parameters that specify bearing dimensions. The bearing aspect ratio (bearing length to bore diameter) and bearing clearance have been determined based on rotor maximum critical speed and minimum response displacement. The analytical solution of rotor Eq. of motion was verified by numerical solution via using ANSYS Mechanical APDL 18.0 and by comparing the numerical solution with the preceding study. The final study results clearly showed that the bearing aspect ratio has little effect on the critical speed, but it has a high effect on the dynamic response also the bearing clearance has little effect on the critical speed and considerable effect on the dynamic response. The study showed that the more accurate values of bearing aspect ratio to make the response of rotor as low as possible are about 0.65 - 1 and bearing percent clearance is about 0.15 - 0.2 for different rotor dimensions.

Performance Improvement of SVPWM-Based Three-Phase Grid-Connected Inverters

2013 ◽  
Vol 732-733 ◽  
pp. 1261-1264
Author(s):  
Zhi Lei Yao ◽  
Lan Xiao ◽  
Jing Xu
Keyword(s):  
Dynamic Response ◽  
Control Strategy ◽  
Pulse Width Modulation ◽  
Control Method ◽  
Grid Current ◽  
Current Controller ◽  
Three Phase ◽  
Reference Grid ◽  
Grid Connected Inverter

An improved control strategy for three-phase grid-connected inverters with space vector pulse width modulation (SVPWM) is proposed. When the grid current contains harmonics, the d-and q-axes grid currents is interacted in the traditional control method, and the waveform quality of the grid current is poor. As the reference output voltage cannot directly reflect the change of the reference grid current with the traditional control strategy, the dynamic response of the grid-connected inverter is slow. In order to solve the aforementioned problems, the d-and q-axes grid currents in the decoupled components of the grid current controller are substituted by the d-and q-axes reference grid currents, respectively. The operating principles of the traditional and proposed control methods are illustrated. Experimental results show that the grid-connected inverter with the improved control strategy has high waveform quality of the grid current and fast dynamic response.

CAFixD: A Case-Based Reasoning Fixture Design Method. Framework and Indexing Mechanisms

2005 ◽  
Vol 6 (1) ◽  
pp. 40-48 ◽  
Author(s):  
Iain M. Boyle ◽  
Kevin Rong ◽  
David C. Brown
Keyword(s):  
Design Method ◽  
Critical Issue ◽  
Design Solution ◽  
Case Based Reasoning ◽  
Fixture Design ◽  
Functional Requirements ◽  
Rigorous Approach ◽  
Machining Operations ◽  
Case Based ◽  
Individual Requirement

Fixtures accurately locate and secure a part during machining operations. Various computer-aided fixture design (CAFD) methods have been developed to reduce design costs associated with fixturing. One approach uses a case-based reasoning (CBR) method where relevant design experience is retrieved from a design library and adapted to provide a new design solution. Indexing design cases is a critical issue in CBR, and CBR systems can suffer from an inability to distinguish between cases if indexing is inadequate. This paper presents CAFixD, a CAFD methodology that adopts a rigorous approach to defining indexing attributes based upon axiomatic design functional requirement decomposition. A design requirement is decomposed in terms of functional requirements, physical solutions are retrieved and adapted for each individual requirement, and the design is then reconstituted to form a complete fixture design. This paper presents the CAFixD framework and operation, and discusses in detail the indexing mechanisms used.

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