The Simulation Studies of PWM Voltage Source Rectifier under Unbalanced Grid Voltage

2014 ◽  
Vol 597 ◽  
pp. 468-471
Author(s):  
Jun Li Zhang ◽  
Yu Ren Li
Keyword(s):  
Power Quality ◽  
Control Strategies ◽  
Positive Sequence ◽  
Voltage Source ◽  
Simulation Studies ◽  
Grid Voltage ◽  
Sinusoidal Input ◽  
Four Quadrant ◽  
Negative Sequence Current ◽  
Unbalanced Grid

Under the balanced or unbalanced grid voltage, the PWM voltage source rectifiers should have many advantages such as sinusoidal input current, unity power factor, four-quadrant operation, the DC voltage stability, etc., so it can be employed in very broad application field. When there is only fundamental positive sequence current component in AC current, the voltage in DC side will remain constant, the rectifier will achieve efficient transformation of power quality. It is necessary to start from control strategies to eliminate harmful components such as the negative sequence current, to improve power quality in rectifier transformation. The mathematical model of PWM rectifier under unbalanced grid voltage was established in the synchronous rotating coordinate system in this paper. The simulation studies of rectifier under unbalanced grid voltage were conducted

scholarly journals PIDR Sliding Mode Current Control with Online Inductance Estimator for VSC-MVDC System Converter Stations under Unbalanced Grid Voltage Conditions

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2599 ◽  
Author(s):  
Weipeng Yang ◽  
Hang Zhang ◽  
Jungang Li ◽  
Aimin Zhang ◽  
Yunhong Zhou ◽  
...  
Keyword(s):  
Reactive Power ◽  
Sliding Mode ◽  
Current Control ◽  
Operating Conditions ◽  
Gradient Algorithm ◽  
Positive Sequence ◽  
Voltage Source ◽  
Grid Voltage ◽  
Wide Range ◽  
Unbalanced Grid

This study aims to present a novel proportional-integral-derivative-resonant law-based sliding mode current control strategy with online inductance estimator (PIDR-SMCC-OIE) for voltage source converter medium voltage direct current (VSC-MVDC) system converter stations under unbalanced grid voltage conditions. A generalized current reference calculation method, by which the ratio of the amplitude of the active power ripple to that of the reactive power ripple can be continuously controlled without current distortion is presented. A dynamic model of the current control errors in the positive sequence synchronous reference frame is developed, and a PIDR law-based sliding mode current controller is designed, where derivatives of the current references are obtained by simple algebraic operations. An OIE adopting the dynamic filtering method and gradient algorithm is proposed to further improve system robustness. In this OIE, the converter pole voltages are obtained by computation utilizing the gate signals of the switching devices and the DC bus voltage, so that no additional voltage sensors are needed. To verify effectiveness of the PIDR-SMCC-OIE strategy, simulation studies on a two-terminal VSC-MVDC system are conducted in PSCAD/EMTDC. The results show it can provide satisfactory performance over a wide range of operating conditions.

scholarly journals A PLL Scheme for Synchronization with Grid Voltage Phasor in Active Power Filter Systems

2010 ◽  
Vol 27 (1) ◽  
pp. 134-137 ◽  
Author(s):  
Oskars Krievs ◽  
Ingars Steiks ◽  
Leonids Ribickis
Keyword(s):  
Active Power Filter ◽  
Active Power ◽  
Active Filter ◽  
Positive Sequence ◽  
Voltage Source ◽  
Grid Voltage ◽  
Active Power Filters ◽  
Voltage Source Inverters ◽  
Power Filter ◽  
Power Filters

A PLL Scheme for Synchronization with Grid Voltage Phasor in Active Power Filter SystemsVoltage source inverters connected to the grid in applications such as active power filters require synchronization with the grid voltage. Since in practice the grid voltage can be unbalanced and distorted, but the operation of the whole active filter control system is strongly dependant on precise estimation of grid voltage phase, the fundamental positive sequence phasor of the grid voltage has to be extracted. In this paper a system for smooth estimation of the position of the voltage phasor at the point of common coupling of a parallel active filter system is presented using a sinusoidal signal integrator and a simple software PLL. The performance of the proposed system is verified by simulation and experimental results. The proposed PLL scheme can also be used in other vector oriented control systems.

scholarly journals Enhancing Power Quality in PV-SOFC Microgrids Using Improved Particle Swarm Optimization

2019 ◽  
Vol 9 (5) ◽  
pp. 4616-4622
Author(s):  
V. V. Prabhakaran ◽  
A. Singh
Keyword(s):  
Particle Swarm Optimization ◽  
Power Systems ◽  
Power Quality ◽  
Electricity Markets ◽  
Large Scale ◽  
Control Strategies ◽  
Particle Swarm ◽  
Voltage Source ◽  
Swarm Optimization ◽  
Improved Particle Swarm Optimization

The concept of hybrid microgrid (MG) has attracted tremendous attention in modern electricity markets, owing to the enhanced efficiency and reliability it offers to the main electricity grid. Numerous meritorious aspects associated with hybrid MGs are the key features of future large scale renewable technologies. In this paper, a hybrid MG using PV-SOFC (PhotoVoltaic – Solid Oxide Fuel Cell) is connected to an infinite bus bar, in order to achieve an autonomous working mode. The dynamic and steady-state operation with control strategies for both PV and SOFC power systems are analyzed. The objective is to control the voltage and frequency of the MG when it is not connected to the main grid. Typically, an efficient control strategy must assess the power conversion system and its state, in the isolated MG. Moreover, it must reliably handle variant and intermittent type of loads. With this viewpoint, we propose a Voltage Source Inverter (VSI) based Proportional Integral (PI) controller, optimized by Improved Particle Swarm Optimization (IPSO) for the purpose of smooth power flow control improving power quality. The performance of PI-IPSO and PI technologies are evaluated, for the proposed MG, in MATLAB/Simulink. The results obtained verify the effectiveness of the modified PSO algorithm, in comparison to the conventional PI techniques, for the frequency and voltage control of the MG.

Current predictive control of three-phase voltage source PWM rectifiers under unbalanced grid voltage conditions

2016 ◽  
Vol 39 (7) ◽  
pp. 976-986
Author(s):  
Meng Wang ◽  
Yanyan Shi ◽  
Zhen Qi ◽  
Minghui Shen
Keyword(s):  
Predictive Control ◽  
Control Strategy ◽  
Voltage Source ◽  
Phase Voltage ◽  
Two Phase ◽  
Grid Voltage ◽  
Three Phase ◽  
Pwm Rectifiers ◽  
Current Error ◽  
Unbalanced Grid

To improve the performance of three-phase voltage source pulse-width modulated (PWM) rectifiers (VSR) under unbalanced grid voltage conditions, a fixed-frequency current predictive control (CPC) strategy is presented. Instantaneous power of the three-phase VSR is analysed in a two-phase stationary frame. The calculation method for the reference current is improved to achieve the power stability at the AC side of the rectifier. Based on the current predictive model, the optimal duration of the voltage vectors is computed under the restricted condition of minimizing current error at α- and β-axes in fixed intervals. The control system is free of synchronous rotation coordinate transformation, and avoids positive and negative sequence decomposition, which simplifies the calculation. The simulation and experimental results show that the proposed control strategy is able to eliminate the AC current distortion effectively and depress DC link voltage fluctuation under unbalanced grid voltage. Furthermore, the control strategy has faster dynamic response ability, enhancing the control performance of the three-phase VSR system.

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