MSHE-PWM Control of Modular Multilevel Direct Current Transmission System

2015 ◽  
Vol 9 (1) ◽  
pp. 553-559
Author(s):  
HU Xin-xin ◽  
Chen Chun-lan
Keyword(s):  
Pulse Width Modulation ◽  
Reactive Power ◽  
Balance Control ◽  
Electric Energy ◽  
Access Point ◽  
Experimental Result ◽  
Switching Frequency ◽  
Pwm Control ◽  
Harmonic Elimination

In order to optimize the electric energy quality of HVDC access point, a modular multilevel selective harmonic elimination pulse-width modulation (MSHE-PWM) method is proposed. On the basis of keeping the minimum action frequency of the power device, MSHE-PWM method can meet the requirement for accurately eliminating low-order harmonics in the output PWM waveform. Firstly, establish the basic mathematical model of MMC topology and point out the voltage balance control principle of single modules; then, analyze offline gaining principle and realization way of MSHEPWM switching angle; finally, verify MSHE-PWM control performance on the basis of MMC reactive power compensation experimental prototype. The experimental result shows that the proposed MSHE-PWM method can meet such performance indexes as low switching frequency and no lower-order harmonics, and has verified the feasibility and effectiveness thereof for optimizing the electric energy quality of HVDC access point.

scholarly journals Research on hybrid SHEPWM based on different switching patterns

2019 ◽  
Vol 10 (4) ◽  
pp. 1875 ◽  
Author(s):  
Tao Jing ◽  
Alexander Maklakov ◽  
Andrey Radionov ◽  
Sergei Baskov ◽  
Aleksandra Kulmukhametova
Keyword(s):  
Pulse Width ◽  
Pulse Width Modulation ◽  
Effective Means ◽  
Switching Frequency ◽  
Harmonic Elimination ◽  
Switching Patterns ◽  
Control Scheme ◽  
Selective Harmonic Elimination ◽  
Simulation Results ◽  
Additional Hardware

<span>This paper presents a hybrid pulse width modulation (HPWM) strategy based on different switching patterns of selective harmonic elimination pulse width modulation (SHEPWM) for the three-level neutral point clamped (3L-NPC) converter. Specific low-order harmonics can be eliminated by SHEPWM at low switching frequency, while the remaining high-order harmonics can be selected to be simply filtered by additional hardware. Large oscillation waveform usually occurs in the transition instant between two diverse modulation situations, therefore switching between distinct switching patterns can be problematic if no effective means is taken, especially when the effect of smooth and fast transition at any time is considerable. A universal and valid control strategy, which maintains the high-quality output voltage and current, is proposed and implemented in this paper to address this issue. Simulation results obtained from MATLAB/SIMULINK are presented to analyze the performance and validate the feasibility and effectiveness of this control scheme.</span>

scholarly journals Flyback Cascaded Multilevel Inverter Based SHE-PWM Control for STATCOM Applications

2017 ◽  
Vol 8 (1) ◽  
pp. 100 ◽  
Author(s):  
Kah Haw Law ◽  
Wendy Pei Qin Ng ◽  
Wei Kitt Wong
Keyword(s):  
Closed Loop ◽  
Pulse Width Modulation ◽  
Reactive Power ◽  
Performance Enhancement ◽  
Static Synchronous Compensator ◽  
Loop Control ◽  
Flyback Converter ◽  
Harmonic Elimination ◽  
Multi Level ◽  
Cascaded Multilevel Inverter

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.

scholarly journals A VSC Transmission System Using Flying Capacitor Multilevel Converters and Selective Harmonic Elimination PWM Control

2006 ◽  
Vol 5 (2) ◽  
Author(s):  
Lie Xu ◽  
Vassilios G. Agelidis
Keyword(s):  
Pulse Width Modulation ◽  
Control Method ◽  
Transmission System ◽  
Voltage Source ◽  
Pwm Control ◽  
Multilevel Converters ◽  
Harmonic Elimination ◽  
Selective Harmonic Elimination ◽  
Small Change ◽  
Current Polarity

A transmission system based on voltage-source three-level flying capacitor (FC) multilevel converters with selective harmonic elimination pulse-width modulation (SHE-PWM) control is presented in this paper. The generation of the switching patterns for each power device is described taking into account the natural balancing of the FC voltages. A new and simple control method for balancing the FC voltages of the FC converter when using SHE-PWM is proposed which is based on the small change of the firing angle according to the load current polarity. Implementation of the SHE-PWM with capacitor voltage balancing is provided. Simulation studies for a 300MW/+-150kV transmission system are presented to confirm the satisfactory performance of the proposed system.

scholarly journals A Multi-Functional De-Icing Equipment Using Modular Parallel PWM Current Source Converters

2021 ◽  
Vol 256 ◽  
pp. 01033
Author(s):  
Yang Hu ◽  
Heng Zhang ◽  
Jing Chen ◽  
Huan Zhang ◽  
Xinmeng Liu ◽  
...  
Keyword(s):  
Reactive Power ◽  
Low Voltage ◽  
Current Source ◽  
Modulation Method ◽  
Switching Frequency ◽  
Common Mode ◽  
Common Mode Voltage ◽  
Current Sharing ◽  
Harmonic Elimination ◽  
Switching State

For transmission line de-icing, a five level specific harmonic elimination (5l-she) modulation method for high-power parallel current source is proposed, which realizes the current balance of DC bridge arm and the suppression of common mode voltage, and ensures the power quality of grid connected current at low switching frequency. In addition the reactive power of the low voltage load can be compensated at the same time. Firstly, the switching states are classified according to the different mode lengths of PWM current, and the common mode voltage corresponding to each switching state is calculated. Secondly, the current sharing control strategy is established based on the analysis of the influence of redundant switching state on the current sharing of DC bridge arm. Then, the 5l-she waveform is constructed based on the switching state with lower common mode voltage, and the redundant switching states is optimized according to the current sharing strategy. Finally, the effectiveness of the proposed method is verified by simulation.

scholarly journals PROPOSAL FOR MANAGING ELECTRIC ENERGY QUALITY IN THE LV GRID USING ON-LOAD TAP CHANGER WITH A STATIC SYNCHRONOUS COMPENSATOR

2018 ◽  
Vol 8 (2) ◽  
pp. 72-78
Author(s):  
Bartłomiej Mroczek ◽  
Karol Fatyga
Keyword(s):  
Reactive Power ◽  
Low Voltage ◽  
Power Grid ◽  
Electric Energy ◽  
Auxiliary Equipment ◽  
Static Synchronous Compensator ◽  
Voltage Quality ◽  
Tap Changer ◽  
Load Tap Changer

The paper proposes the use of auxiliary equipment in the low voltage network: an on-load tap changer and a static synchronous compensator (STATCOM) to improve the quality of energy supply to end users. As part of the research, a section of medium and low voltage power grid was modelled using Matlab & Simulink software, which was tested in three scenarios. The first scenario presents the operation of the power grid with the on-load tap changer installed in the transformer block. The second scenario uses the STATCOM for local reactive power compensation. Additionally, the third scenario is the combined work of the on-load tap-changer along with the STATCOM. According to the authors, the method discussed does not bring the expected results in the area of voltage quality improvement, indicating that further research is required, including tests with energy storage.

scholarly journals A New Method of Selective Harmonic Elimination PWM for H-Bridge Cascaded Multilevel Inverter

2019 ◽  
Vol 9 (1) ◽  
pp. 6168-6175
Keyword(s):  
Degrees Of Freedom ◽  
Pulse Width Modulation ◽  
Harmonic Distortion ◽  
Multilevel Inverter ◽  
Voltage Range ◽  
Harmonic Elimination ◽  
Selective Harmonic Elimination ◽  
Cascaded Multilevel Inverter ◽  
Operating Points

The quality of power of the cascaded H-bridge multilevel inverter is affected due to harmonics. In this paper, a Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) method including controllable DC link voltage is introduced for the multilevel inverter. Novel mathematical modeling of SHE-PWM is established concerning the DC link voltage. Compared to ordinary selective harmonic elimination, the proposed method has an increased number of degrees of freedom because of its variable DC link voltage. On the other hand, the selective harmonic elimination utilizes constant DC link voltage. In the proposed scheme, the nonlinear equations are solved only once in the entire voltage range. As a result, the computational burden will decrease. Also, the Total Harmonic Distortion (THD) of the output voltage remains constant for various values of the operating points. The simulation is performed using Matlab Simulink and the comparison is performed with the conventional PWM method. It is intended that the proposed SHE-PWM based cascaded H-bridge multilevel inverter provides better performance in terms of lower-order harmonics and less THD compares to conventional PWM method.

scholarly journals Performance Evaluation of Eleven-Phase Induction Machine with Different PWM Techniques

2015 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
M.I. Masoud ◽  
A.S. Abdelkhalik
Keyword(s):  
Comparative Study ◽  
Pulse Width Modulation ◽  
Induction Machine ◽  
Single Pulse ◽  
Torque Ripple ◽  
Switching Frequency ◽  
Pulse Modulation ◽  
Medium Voltage ◽  
Harmonic Elimination ◽  
Power Switches

Multiphase induction machines are used extensively in low and medium voltage (MV) drives. In MV drives, power switches have a limitation associated with switching frequency. This paper is a comparative study of the eleven-phase induction machine’s performance when used as a prototype and fed sinusoidal pulse-width-modulation (SPWM) with a low switching frequency, selective harmonic elimination (SHE), and single pulse modulation (SPM) techniques. The comparison depends on voltage/frequency controls for the same phase of voltage applied on the machine terminals for all previous techniques. The comparative study covers torque ripple, stator and harmonic currents, and motor efficiency. 

scholarly journals Modeling and Compensation for Dead-Time Effect in High Power IGBT/IGCT Converters with SHE-PWM Modulation

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4348 ◽  
Author(s):  
Jingling Cheng ◽  
Dongdong Chen ◽  
Guozhu Chen
Keyword(s):  
High Power ◽  
Pulse Width Modulation ◽  
Power Converters ◽  
Dead Time ◽  
Open Loop ◽  
Time Effect ◽  
Operating Conditions ◽  
Switching Frequency ◽  
Harmonic Elimination ◽  
The Dead

Research on applying selective harmonic elimination pulse width modulation (SHE-PWM) to high power converters has drawn tremendous interest, due to the advantages of low switching frequency and high output harmonic performance. In the fields of high power converters such as variable speed traction motor drives and static synchronous compensators (STATCOM), the adoption of high voltage but slow speed semiconductor devices, i.e., IGBT/IGCT, results in a longer dead time of several microseconds, which leads to a motor vibration in the former case or the distortion of grid current in the latter case. This paper analyzes in detail the mechanism of the dead-time effect on 3-level SHE-PWM with different operating conditions considered. For the first time, a general mathematical model describing the relationship between the dead time and harmonic distribution of SHE-PWM wave is established. Based on which an open-loop compensation method by inserting a margin time into the effective switching angles is proposed. Furthermore, a closed-loop controller that implements online adaptive adjustment of the margin time is designed in case of a variable frequency application. The effectiveness of the proposed method in different scenarios is verified through simulation results.

Impact of PWM control frequency on efficiency of drive with 1 kW permanent magnet synchronous motor

2018 ◽  
Vol 37 (1) ◽  
pp. 307-318 ◽  
Author(s):  
Tomasz Rudnicki ◽  
Andrzej Sikora ◽  
Robert Czerwinski ◽  
Tadeusz Glinka
Keyword(s):  
Permanent Magnet ◽  
Pulse Width Modulation ◽  
Rotation Speed ◽  
Permanent Magnet Synchronous Motor ◽  
Drive System ◽  
Switching Frequency ◽  
Pwm Control ◽  
Content Type ◽  
Control Frequency ◽  
The Impact

Purpose This paper aims to present the impact of Pulse Width Modulation (PWM) control frequency for specific Permanent Magnet Synchronous Motors (PMSMs) on the efficiency of the entire driving unit. Examinations were carried out for a PMSM unit with a power of 1 kW, rated speed of 1,000 rpm, and rated torque of 6 Nm. Design/methodology/approach The PWM frequency ranged from 4 to 20 kHz with increments of 1 kHz. Measurements were taken for each of the foregoing frequencies, for the different load torques, and for the different rotation speeds including overspeed. The results achieved allow the PWM control frequency to be properly adjusted for each PMSM to operate the entire driving unit in the most efficient way and, in consequence, save energy consumed by the drive. Findings Obtained results may be used as a kind of background for the design of drive system. Research limitations/implications For a specific PMSM-based drive system, one can find the optimal PWM control frequency. This frequency depends on the rotation speed and torque of the motor. However, the validity of the results presented in the paper is limited. They are valid for the specific motor drive under test and cannot be generalized easily. Originality/value This work shows that there is some maximal efficiency of the entire system depending on the rotation speed, load torque and switching frequency of the power transistors. For a specific motor working in a certain condition, we can find the minimum power loss.

scholarly journals Symmetrical Cascaded Switched-Capacitor Multilevel Inverter Based on Hybrid Pulse Width Modulation

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7643
Author(s):  
Lingling Cao ◽  
Jiefeng Lin ◽  
Shikai Chen ◽  
Yuanmao Ye
Keyword(s):  
Pulse Width ◽  
Output Voltage ◽  
Pulse Width Modulation ◽  
Reactive Power ◽  
Input Voltage ◽  
Industrial Applications ◽  
Multilevel Inverter ◽  
Switching Frequency ◽  
Switched Capacitor ◽  
Cascaded Multilevel Inverter

Multilevel inverters have been widely used in various industrial applications such as renewable energy generation and electric vehicles. An improved circuit of symmetrical cascaded switched-capacitor multilevel inverter is proposed so that the reactive power is absorbed by its power supply instead of capacitors. Then, a special hybrid pulse width modulation strategy combing level-shifted pulse width modulation (LS-PWM) and phase-shifted pulse width modulation (PS-PWM) was developed for the inverter. With this modulation algorithm, the power between cascaded units is automatically balanced, and the voltage of the capacitor in each unit is also automatically balanced to the dc input voltage. In addition, the optimized capacitor voltage ripple makes it possible to use a smaller capacitor to produce a better output voltage waveform. Theoretical analysis, simulation and experimental results show that the equivalent switching frequency of the cascaded multilevel inverter is twice the original frequency so that the output voltage harmonics are only distributed near even multiples of the carrier frequency.

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