scholarly journals Analysis of Cross-Connected Half-Bridges Multilevel Inverter for STATCOM Application

Electronics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1898
Author(s):  
Yuan Li ◽  
Muhammad Humayun

This paper suggested a single-phase cross-connected half-bridges multilevel inverter (cchb-mli) topology for static synchronous compensator (statcom) applications. The proposed mli structure consists of cross-connected multilevel cells connected in series with a more optimized number of devices to synthesize a higher number of voltage steps. Each cell in the structure consists of a set of switches and a dc-capacitor. Typically, when several dc-capacitors are used in an inverter, the dc voltages fluctuation occurs due to tolerance between passive element and asymmetric switch losses. A dual-loop control technique has been proposed with level-shifted pulse width modulation pwm to overcome these issues. The proposed methodology balances the dc-voltages using a proportional-integral controller by adjusting the switch duty cycle. The control method helps offset the issue of aggravated fluctuation while preserving the delivered reactive power distributed equally among the dc-capacitors at the same time. A thorough comparison is made between the proposed inverter concerning the number of components and efficiency to demonstrate the effectiveness of previous topologies. Moreover, a simulation model built in simulink and experimental results take from laboratory prototype to confirm the effectiveness of proposed structure and its control technique.

Author(s):  
Kah Haw Law ◽  
Wendy Pei Qin Ng ◽  
Wei Kitt Wong

This paper presents the closed loop DC-DC flyback converter with multi-level cascaded H-bridge inverter (MCHI) for transformer-less static synchronous compensator (STATCOM) system. The STATCOM system is proposed to be controlled using decoupled dq vector control incorporating the new reactive current reference algorithm and multi-level selective harmonic elimination pulse width modulation (MSHEPWM) technique. This ensures transient performance enhancement as well as simpler control and modulation technique implementation for dynamic systems. As the proposed MSHEPWM solely depends on adjustable DC-link voltage levels, flyback converter is designed for that purpose to suit wider applications. In current work, a single phase five-levels CHI based STATCOM system incorporated with the aforementioned converters are presented to compensate the reactive power (VAR) at the point of common connection (PCC). The dynamic as well as the transient performances of the developed STATCOM control system and the proposed voltage closed loop control of each converter are investigated to meet different VAR demands at balanced loading conditions. Simulation studies are performed to verify the effectiveness and theoretical analysis of the approaches presented.


2013 ◽  
Vol 415 ◽  
pp. 81-88
Author(s):  
Yang Xue ◽  
Yuan Li ◽  
Jia Dong Zhang ◽  
Jing Lin ◽  
Jun Tao Yang

The space vector pulse width modulation (SVPWM), as a new kind of vector control technique, has the advantages of high voltage utilization, less distorted output, simple control method, etc. In this paper, the control technique is applied to three-phase photovoltaic (PV) grid-connected inverter system. It uses double loop control method combined with PI control technique. The simulation model of PV grid-connected inverter system is established in Matlab/Simulink. The simulation results show that the application of SVPWM technique effectively improves the dynamic performance of PV grid inverter system and the THD of grid-connected current is low.


2013 ◽  
Vol 448-453 ◽  
pp. 2167-2170
Author(s):  
Kai Li ◽  
Yi Hui Zheng ◽  
Xin Wang ◽  
Li Xue Li ◽  
Gang Yao ◽  
...  

To realize the STATCOM based on Modular Multilevel Converter (MMC), a simplified double-closed loop structure, simplifying from the control method of High Voltage Direct Current (HVDC) based on MMC, is presented. Considering MMCs DC side using capacitors, a part-controlling method based on energy balancing is proposed, to solve the voltage balancing problem. With the part-controlling fixing the changing capacitors voltage and the simplified double-closed loop control method, voltage fluctuation could be reduced, and the loads reactive power could be compensated. The correctness and the effectiveness of the MMC-STATCOM controlling scheme is verified by Matlab/Simulink.


2012 ◽  
Vol 516-517 ◽  
pp. 1722-1727 ◽  
Author(s):  
Wei Jun Yun ◽  
Gang Yao ◽  
Li Dan Zhou ◽  
Chen Chen ◽  
Jun Min Pan

Nowadays Static Synchronous Compensator (STATCOM) has gradually become one of the representative techniques in the field of dynamic reactive power compensation in the power distribution system. This paper analyzed the topology and the voltage imbalance problem of the up and down capacitors on DC side of the three-phase four-wire STATCOM. In allusion to the imbalance problem of neutral point, a novel control strategy based on the control of zero-sequence current was proposed. By the triple close-loop control strategy, the STATCOM can achieve great control accuracy and dynamic performance. Simulation result proves that the proposed control method is effective.


2009 ◽  
Vol 628-629 ◽  
pp. 257-262 ◽  
Author(s):  
Tong Xing

The cutter head drive hydraulic system of φ1.8m simulate shield machine is introduced in this article, which has the variable speed pump control technique and the closed loop control method. The AMESim simulation model of the hydraulic system is built up, and the efficiency of the hydraulic system, speed control performance by open loop and closed loop control are analyzed. The result of the simulation shows that the variable speed pump control system has higher efficiency than the variable displacement pump control system about 4%-26% in the same condition when the cutter head speed is at the range of 0.5-4r/min, and the hydraulic system has good dynamic characteristics in closed-loop PID control.


2013 ◽  
Vol 732-733 ◽  
pp. 1354-1357
Author(s):  
Shi Wang Yang ◽  
Peng Li ◽  
Chang Wang ◽  
Jia Ming Li

How to ensure the security, stability and economic operation of microgrid in different operation modes is a difficult problem of microgrid research. There is active power and reactive power coupling in the regulation of frequencies and voltages because of the line parameter characteristics of microgrid. The defect of the traditional active power-frequency, reactive power-voltage droop control is analyzed and a novel decoupling droop control method for low voltage microgrid is proposed in this paper. At last, the multiple feedback loop control strategy for inverters on the basis of this proposed method and a microgrid simulation model are established. The comparative analysis between the new method and the traditional method based on the simulation results can prove that the proposed control method is simple in design, and it can assure an excellent power quality and realize the reasonable distribution of active power and reactive power between distributed generations.


Author(s):  
Hajar Chadli ◽  
Sara Chadli ◽  
Mohamed Boutouba ◽  
Mohammed Saber ◽  
Abdelwahed Tahani

Renewable energy sources are considered as inexhaustible sources for the very long-term, as they come from natural processes that are constantly replenished. However, there are a number of challenges facing renewable energy technology adoption, like the grid connecting problems. One of the main challenges relates to the grid connecting problem is the power quality issues for power converter, such as harmonics, voltage stability, and frequency fluctuation. Hence, the inverter remains the first element to be built because of its undeniable advantages in alternative continuous conversion. However, it has some disadvantages such as high component count and complex control method. This paper presents the design and implementation of a new 7-level inverter architecture with only six switches. This architecture requires fewer components compared to other 7-level inverter topologies therefore, the overall cost, control technique complexity, and conduction losses are highly reduced. A digital phase opposition disposition sinusoidal pulse width modulation (POD-SPWM) strategy using the Arduino is adopted to improve the performance of the proposed multilevel inverter (MLI) which leads to further reduction in total harmonic sistortion (THD). In this paper, the proposed inverter is tested using Proteus software and Matlab Simulink. Finally, a laboratory setup of the proposed inverter was built to validate its workability by the experimental results.


Author(s):  
Prabodha Kumar Rath ◽  
Kanhu Charan Bhuyan

<span lang="EN-US">This paper proposes a model of a VSC (voltage source converter) based Back to Back HVDC system and its control technique under fault condition. From the mathematical model of the system relationship between the controlling and the controlled variables is determined to control the system parameters. An appropriate vector control technique is used to control active and reactive power and to maintain DC link voltage. The proposed controlling unit consists of outer control loop and inner control loop which effectively damped out the system oscillation and maintains the system stability. The validity of the model and the feasibility of the control method have been proved by the simulation results. In this paper the system performance is studied under fault condition is studied.</span>


Author(s):  
N. Susheela ◽  
P. Satish Kumar

<p>The popularity of multilevel inverters have increasing over the years in various applications without use of a transformer and has many benefits. This work presents the performance and comparative analysis of single phase diode clamped multilevel inverter and a hybrid inverter with reduced number of components. As there are some drawbacks of diode clamped multilevel inverter such as requiring higher number of components, PWM control method is complex and capacitor voltage balancing problem, an implementation of hybrid inverter that requires fewer components and less carrier signals when compared to conventional multilevel inverters is discussed. The performance of single phase diode clamped multilevel inverter and hybrid multilevel inverter for seven, nine and eleven levels is performed using phase disposition, alternate phase opposition disposition sinusoidal pulse width modulation techniques. Both the multilevel inverter are implemented for the above mentioned multicarrier based Pulse Width Modulation methods for R and R-L loads.  The total harmonic distortion is evaluated at various modulation indices. The analysis of the multilevel inverters is done by simulation in matlab / simulink environment.</p>


2020 ◽  
Vol 184 ◽  
pp. 01041
Author(s):  
Krishna S. Patel ◽  
Vijay H. Makwana

This paper presents the modified grid side converter control (GSC) technique which enable the GSC to work as a shunt active filter to mitigate the grid current harmonics produced by the nonlinear load, as well as to transfer power from the grid to the rotor of doubly fed induction generator (DFIG) or vice versa. The main contribution of this proposed technique is an addition of a shunt active filter with space vector pulse width modulation (SVPWM) controller in GSC control itself in order to achieve a better grid current %THD profile, and simultaneously to control active power for variable wind speed. The reactive power supply to the DFIG and extraction of maximum power is achieved using RSC. The comparison of the modified GSC control technique using hysteresis current control (HCC), and SVPWM controller used to mitigate the harmonics is presented with different wind speeds. The proposed modified GSC control technique is simulated for grid-connected 2.6 MW DFIG based wind energy conversion system (WECS) in MATLAB Simulink environment.


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