scholarly journals Grid-Connected Resonance Suppression Of Group-Series Photovoltaic Cluster Inverters Based On Hybrid Damping

2021 ◽  
Vol 2136 (1) ◽  
pp. 012020
Author(s):  
Shengqing Li ◽  
Zhijian Wang
Keyword(s):  
Harmonic Distortion ◽  
Current Loop ◽  
Output Current ◽  
Resonance Mechanism ◽  
Current Feedback ◽  
Parallel Voltage ◽  
The Mathematical Model ◽  
Parallel Current ◽  
Suppression Strategy ◽  
Hybrid Damping

Abstract Grid-connected group-series photovoltaic cluster inverter system will cause resonance, which will adversely affect the system. To suppress grid-connected resonance, the mathematical model, resonance mechanism and resonance characteristics of the cluster inverters are analyzed, and a global resonance suppression strategy based on hybrid damping is proposed. In the current loop of the inverter, capacitive current feedback and parallel voltage proportional feed-forward are introduced as active dampers to reduce the harmonics of the parallel current. On this basis, RLC type second-order resonance suppression circuit is added as passive damping to suppress system resonance, so that the output current of the inverters can meet the grid-connected conditions when the cluster is connected to the grid. The simulation and experimental results show that the total harmonic distortion of the grid-connected current decreases from 10.54% to 1.97% after three series photovoltaic cluster inverters adopt this strategy, which effectively suppresses the grid-connected resonance.

A multi-valve controlled saturable reactor and its harmonic optimization

2014 ◽  
Vol 33 (4) ◽  
pp. 1346-1365 ◽  
Author(s):  
Yifan Wang ◽  
Guozhu Chen
Keyword(s):  
Mathematical Model ◽  
Harmonic Analysis ◽  
Harmonic Distortion ◽  
Iron Core ◽  
Harmonic Suppression ◽  
Output Current ◽  
Harmonic Compensation ◽  
Content Type ◽  
Current Harmonics ◽  
The Mathematical Model

Purpose – As arc suppression coils (ASCs), magnetically controlled reactors (MCRs) are usually operated in the single-phase mode. Due to the lack of a third order harmonic compensation circuit, the current harmonics are high. The purpose of this paper is to propose a novel structure of MCR and a genetic algorithm (GA) to determine the parameters which will result in minimum total harmonics. Design/methodology/approach – This paper proposes the structure and the working principle of the multi-valve controlled saturable reactor (MCSR). There are several sorts of magnetic valves in the iron cores of the MCSR. The saturation degree of each magnetic valve is different when the same direct component of the magnetic flux is generated in the iron core, therefore current harmonics of different phases emerging, i.e. the total harmonics can be reduced. The magnetization characteristics and the mathematical model of the current harmonics of the MCSR are presented by introducing three parameters. The optimal values of the parameters that result in the smallest total harmonic distortion in the output current are calculated by a GA. Findings – The simulation and experimental results are coincident with the theoretical analyses, which prove the effectiveness of the proposed method on harmonic suppression. Practical implications – The method proposed in this paper can successfully reduce the current harmonics of the conventional MCR, including but not limited to the ASC. A prototype MCSR (540 kVA/10 kV) has been designed and constructed. Originality/value – In this paper, a MCSR is proposed. The mathematical model of the MCSR for harmonic analysis is developed. The optimal parameters that result in the smallest THD in the output current are calculated. The mathematical model can be also used for the harmonic analysis of conventional MCRs.

scholarly journals Harmonic Suppression Strategy of Photovoltaic Grid Connected Inverter Based on Repetitive and PI Control

2021 ◽  
Vol 2136 (1) ◽  
pp. 012032
Author(s):  
Shengqing Li ◽  
Wang Han ◽  
Xiaobao Li ◽  
Zhijian Wang
Keyword(s):  
Dynamic Performance ◽  
Pi Control ◽  
Harmonic Suppression ◽  
Current Feedback ◽  
Current Harmonics ◽  
Current Controller ◽  
Grid Connected Inverter ◽  
The Mathematical Model ◽  
Suppression Strategy ◽  
Harmonic Problem

Abstract To address the serious harmonic problem of grid connected current in photovoltaic grid-connected inverter, a harmonic suppression strategy based on Repetitive and PI control is proposed in this thesis. According to this strategy, the mathematical model of LCL photovoltaic grid-connected inverter is established with the harmonic mechanism analyzed, the repetitive and PI control is added into the current controller, and the capacitive-current feedback is added to enhance the system damping. Furthermore, it puts PI control on the inner loop and the repetitive control on the outer loop to improve the dynamic performance and achieve the harmonic suppression of the system. Moreover, the simulation results show that this method improves the dynamic response ability of the system, and effectively suppress the grid-connected current harmonics as THD of grid-connected current is 19.65% lower than that of PI controller.

Design of Grid Connected Parallel Inverters with Interleaved Phase Shift by Using CAN Bus

2012 ◽  
Vol 591-593 ◽  
pp. 1579-1584
Author(s):  
Jyh Wei Chen ◽  
Huan Fu Lin
Keyword(s):  
Phase Shift ◽  
Harmonic Distortion ◽  
Sine Wave ◽  
Control Area ◽  
Total Output ◽  
Switching Frequency ◽  
Area Network ◽  
Output Current ◽  
Control Area Network ◽  
Master Module

A grid-connected parallel inverter with interleaved phase shift is proposed in this paper. The synchronous are generated by the master module to achieve interleaving phase shift PWM for the parallel inverters connected to grid-tied system that make the inverter to output current to the power line and share the load. TI TMS320F2812 DSP is used for system feedback control with voltage and current by using A/D converters to generate the output current close to sine wave. The expected output current values are determined by the master module and transmitted via CAN (Control area network) between inverter modules. The grid-tied system uses zero-voltage-detection circuit to synchronize the inverter currents with grid voltage. For each switching period, PWM voltage of two inverters are interleaved to reduce the total output current ripple so that the switching frequency can be reduced and the power system EMI problem can be alleviated as well. The experiment results are provided to verify the performance of the proposed system to reduce output current harmonic distortion.

scholarly journals Composite Control Strategy of Output Current of LCL Photovoltaic Grid-Connected Inverter

2021 ◽  
Vol 2136 (1) ◽  
pp. 012015
Author(s):  
Shengqing Li ◽  
Xinluo Li ◽  
Qiang Wu ◽  
Xiafei Long
Keyword(s):  
Control Strategy ◽  
Block Diagram ◽  
Harmonic Distortion ◽  
Harmonic Suppression ◽  
Output Current ◽  
Control Block ◽  
Current Harmonics ◽  
Suppression Effect ◽  
Composite Control ◽  
Grid Connected Inverter

Abstract In order to further optimize the output current harmonic suppression effect of photovoltaic grid-connected inverters, a composite control strategy of LCL type photovoltaic grid-connected inverter output current is proposed. This strategy combines proportional complex integral (PCI) control and repetitive control (RC) in parallel, draws a composite control block diagram, introduces a transfer function, and designs PCI and RC control parameters. Prove that the compound control can reduce current harmonics, achieved the purpose of reducing the steady-state error of the fundamental frequency. And adopts a new PCI composite control strategy, which helps to save the cost of the control system. By building the MATLAB/Simulink simulation platform and establishing the PCI+RC composite control model of LCL photovoltaic grid-connected inverter, the comparison of the simulation results shows that compared with the PI+RC control strategy, the total harmonic distortion rate of the grid-connected current is reduced by 25.77. %, significantly improving the quality of grid-connected current.

scholarly journals Single-Phase Inverter Deadbeat Control with One-Carrier-Period Lag

Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 154
Author(s):  
Wei Yao ◽  
Jiamin Cui ◽  
Wenxi Yao
Keyword(s):  
Output Voltage ◽  
Single Phase ◽  
Harmonic Distortion ◽  
Voltage Source ◽  
Current Loop ◽  
Deadbeat Control ◽  
Additional Advantage ◽  
Power Sources ◽  
Pwm Inverter ◽  
Single Phase Inverter

This paper presents a novel digital control scheme for the regulation of single-phase voltage source pulse width modulation (PWM) inverters used in AC power sources. The proposed scheme adopts two deadbeat controllers to regulate the inner current loop and the outer voltage loop of the PWM inverter. For the overhead of digital processing, the change of duty of PWM lags one carrier period behind the sampling signal, which is modeled as a first-order lag unit in a discrete domain. Based on this precise modeling, the deadbeat controllers make the inverter get a fast dynamic response, so that the inverter’s output voltage is obtained with a very low total harmonic distortion (THD), even when the load is fluctuating. The parameter sensitivity of the deadbeat control was analyzed, which shows that the proposed deadbeat control system can operate stably when the LC filter’s parameters vary within the range allowed. The experimental results of a 2kW inverter prototype show that the THD of the output voltage is less than 3% under resistive and rectifier loads, which verifies the feasibility of the proposed scheme. An additional advantage of the proposed scheme is that the parameter design of the controller can be fully programmed without the experience of a designer.

Implementation of Coupled Inductor Based 7-level Inverter with Reduced Switches

2017 ◽  
Vol 8 (3) ◽  
pp. 1294 ◽  
Author(s):  
R. Palanisamy ◽  
K. Vijayakumar ◽  
Aishwarya Bagchi ◽  
Vachika Gupta ◽  
Swapnil Sinha
Keyword(s):  
Output Voltage ◽  
Control Algorithm ◽  
Harmonic Distortion ◽  
Current Control ◽  
Output Current ◽  
Hysteresis Current Control ◽  
Common Mode Voltage ◽  
Voltage Stress ◽  
Dsp Controller ◽  
Switching Devices

<p>This paper proposes implementation of coupled inductor based 7 level inverter with reduced number switches. The inverter which generates the sinusoidal output voltage by the use of coupled inductor with reduced total harmonic distortion. The voltage stress on each switching devices, capacitor balancing and common mode voltage can be minimized. The proposed system which gives better controlled output current and improved output voltage with diminished THD value. The switching devices of the system are controlled by using hysteresis current control algorithm by comparing the carrier signals with constant pulses with enclosed hysteresis band value. The simulation and experimental results of the proposed system outputs are verified using matlab/Simulink and TMS320F3825 dsp controller respectively.</p>

scholarly journals Power Factor Corrector Based on Parallel Quasi- Resonant Pulse Converter with Fast Current Loop

2013 ◽  
Vol 3 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Yuriy Denisov ◽  
Serhii Stepenko
Keyword(s):  
Power Factor ◽  
High Efficiency ◽  
Harmonic Distortion ◽  
Input Voltage ◽  
Current Loop ◽  
Switching Frequency ◽  
Zero Current Switching ◽  
High Switching Frequency ◽  
Power Factor Corrector ◽  
Pulse Converter

Abstract The problems, devoted to power quality and particularly power factor correction, are of great importance nowadays. The key requirements, which should be satisfied according to the energy efficiency paradigm, are not limited only by high quality of the output voltage (low total harmonic distortion), but also assume minimal power losses (high efficiency) in the power factor corrector (PFC). It could be satisfied by the use of quasi-resonant pulse converter (QRPC) due to its high efficiency at high switching frequency instead of the classical pulse-width modulated (PWM) boost converter. A dynamic model of QRPC with zero current switching (ZCS) is proposed. This model takes into account the main features of QRPC-ZCS as a link of a PFC closed-loop system (discreteness, sharp changes of parameters over switching period, input voltage impact on the gain). The synthesized model is also valid for conventional parallel pulse converter over an active interval of commutation. The regulator for current loop of PFC was synthesized based on digital filter using proposed model by the criterion of fast acting.

scholarly journals Interleaved DC-DC Converter with Discrete Duty Cycle and Open Loop Control

2016 ◽  
Vol 53 (4) ◽  
pp. 14-21
Author(s):  
K. Kroics ◽  
A. Sokolovs
Keyword(s):  
Duty Cycle ◽  
Control Algorithm ◽  
Open Loop ◽  
Current Loop ◽  
Open Loop Control ◽  
Output Current ◽  
Loop Control ◽  
Control Principle ◽  
Conduction Mode ◽  
Current Ripple

Abstract The authors present the control principle of the multiphase interleaved DC-DC converter that can be used to vastly reduce output current ripple of the converter. The control algorithm can be easily implemented by using microcontroller without current loop in each phase. The converter works in discontinuous conduction mode (DCM) but close to boundary conduction mode (BCM). The DC-DC converter with such a control algorithm is useful in applications that do not require precise current adjustment. The prototype of the converter has been built. The experimental results of the current ripple are presented in the paper.

Study of Parallel PFC Technology Based on Parallel Inverters

2012 ◽  
Vol 546-547 ◽  
pp. 320-325
Author(s):  
Min Zhang ◽  
Xu Dong Song ◽  
Zheng Hua Zhu ◽  
Zhen Xing Yin
Keyword(s):  
Harmonic Distortion ◽  
Frequency Doubling ◽  
Current Loop ◽  
Simple Arithmetic ◽  
Nonlinear Load ◽  
High Power Factor ◽  
Circuit Structure ◽  
Capacitor Voltage ◽  
Source Current ◽  
Source Voltage

This paper proposes a parallel PFC technology which is shunted between the power supply and the load. Parallel inverters with frequency-doubling carrier phase shifted SPWM technique is used as the main circuit structure to reduce the device currents rate and switch stress and enhance the equivalent switch frequency. The phase angle of the source current reference is determined by the source voltage, while the magnitude of that is obtained from controlling the DC side capacitor voltage of the inverter. The PFC is realized by inner current loop P control and outer voltage loop PI control for its simple arithmetic, good robustness. The simulation and experimental results show that this system can achieve a high power factor of 0.99 and low total harmonic distortion with linear or nonlinear load. So the validity and efficiency of the proposed parallel PFC technology are confirmed by the numerical results.

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