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1.
This paper presents a novel and efficient control scheme for unified power quality conditioner (UPQC) based on three-level neutral point clamped (NPC) inverter using fuzzy logic techniques. The proposed UPQC is capable of mitigating source current harmonics and compensate all voltage disturbances such as voltage sags, swells, unbalances and harmonics. It is designed by the integration of series and shunt active filters (AFs) sharing a common DC bus capacitor. The DC voltage is maintained constant using proportional integral voltage controller. The synchronous reference frame (SRF) theory is used to get the reference signals for shunt active power filters (APFs) and the power reactive theory (p-q theory) for series APFs. The shunt and series APF reference signals derived from the control algorithm and sensed signals are injected in two controllers to generate switching signals. To improve the UPQC capability, fuzzy logic techniques are introduced to control the series APF. The performances of the proposed UPQC system are evaluated in terms of power factor correction, mitigation of voltage or current harmonics and all other voltage disturbances compensation using Matlab-Simulink software and SimPowerSystem toolbox. The simulation results illustrate the performance of the proposed UPQC at the common connection point of the nonlinear load to improve the power energy quality.  相似文献   

2.
This paper presents a control for a three phase five-level neutral clamped inverter (NPC) for grid connected PV system. The maximum power point tracking (MPPT) is capable of extracting maximum power from the PV array connected to each DC link voltage level. The MPPT algorithm is solved by fuzzy logic controller. The fuzzy MPPT is integrated with the inverter so that a DC–DC converter is not needed and the output shows accurate and fast response. A digital PI current control algorithm is used to remain the current injected into the grid sinusoidal and to achieve high dynamic performance with low total harmonic distortion (THD). The validity of the system is verified through MATLAB/Simulink and the results are compared with three phase three-level grid connected NPC inverter in terms of THD.  相似文献   

3.
This paper proposes a method of maximum power point tracking using adaptive fuzzy logic control for grid-connected photovoltaic systems. The system is composed of a boost converter and a single-phase inverter connected to a utility grid. The maximum power point tracking control is based on adaptive fuzzy logic to control a switch of a boost converter. Adaptive fuzzy logic controllers provide attractive features such as fast response, good performance. In addition, adaptive fuzzy logic controllers can also change the fuzzy parameter for improving the control system. The single phase inverter uses predictive current control which provides current with sinusoidal waveform. Therefore, the system is able to deliver energy with low harmonics and high power factor. Both conventional fuzzy logic controller and adaptive fuzzy logic controller are simulated and implemented to evaluate performance. Simulation and experimental results are provided for both controllers under the same atmospheric condition. From the simulation and experimental results, the adaptive fuzzy logic controller can deliver more power than the conventional fuzzy logic controller.  相似文献   

4.
This paper introduces a technique based on linear quadratic regulator (LQR) to control the output voltage at the load point versus load variation from a standalone proton exchange membrane (PEM) fuel cell power plant (FCPP) for a group housing use. The controller modifies the optimal gains k i by minimizing a cost function, and the phase angle of the AC output voltage to control the active and reactive power output from an FCPP to match the terminal load. The control actions are based on feedback signals from the terminal load, output voltage and fuel cell feedback current. The topology chosen for the simulation consists of a 45 kW proton exchange membrane fuel cell (PEMFC), boost type DC/DC converter, a three-phase DC/AC inverter followed by an LC filter. Simulation results show that the proposed control strategy operated at low commutation frequency (2 kHz) offers good performances versus load variations with low total harmonic distortions (THD), which is very useful for high power applications.  相似文献   

5.
Dynamic voltage restorer (DVR) is used to protect sensitive loads from voltage disturbances of the distribution generation (DG) system. In this paper, a new control approach for the 200 kW solar photovoltaic grid connected system with perturb and observe maximum power point tracking (MPPT) technique is implemented. Power quality improvement with comparison is conducted during fault with proportional integral (PI) and artificial intelligence-based fuzzy logic controlled DVR. MPPT tracks the actual variable DC link voltage while deriving the maximum power from a photovoltaic array and maintains DC link voltage constant by changing modulation index of the converter. Simulation results during fault show that the fuzzy logic based DVR scheme demonstrates simultaneous exchange of active and reactive power with less total harmonic distortion (THD) present in voltage source converter (VSC) current and grid current with fast tracking of optimum operating point at unity power factor. Standards (IEEE-519/1547), stipulates that the current with THD greater than 5% cannot be injected into the grid by any distributed generation source. Simulation results and validations of MPPT technique and operation of fuzzy logic controlled DVR demonstrate the effectiveness of the proposed control schemes.  相似文献   

6.
This paper presents implementation of particle swarm optimization (PSO) algorithm as a C-Mex S-function. The algorithm is used to optimize a 9-rule fuzzy logic controller (FLC) for maximum power point tracking (MPPT) in a grid-connected photovoltaic (PV) inverter. The FLC generates DC bus voltage reference for MPPT. A digital PI current control scheme in rotating dq-reference frame is used to regulate the DC bus voltage and reactive power. The proposed technique simplifies optimal controller design and ensures fast simulation speeds due to seamless integration with the simulation platform. Validity of the proposed method was verified using co-simulation in PSIM and MATLAB/Simulink. Simulation results show that the optimized FLC gives a better performance compared to fixed-step MPPT.  相似文献   

7.
该文针对光伏准Z源逆变器的运行特点,基于逆变器两态滞环电流控制工作原理,提出一种能使逆变器直通实现光伏MPPT的三态滞环控制器和单相准Z源级联逆变器三态滞环控制系统,分析三态滞环控制器的工作原理,并用三单元准Z源级联逆变器系统仿真,对比研究三态滞环控制、载波层叠法和载波移相法的控制效果。仿真结果表明,三态滞环控制调制策略表现出更好的稳态和动态响应性能,其并网电流谐波畸变率更小。  相似文献   

8.
将输入输出反馈精确线性化控制方法应用于三相有源电力滤波器非线性控制中。首先建立三相有源电力滤波器的仿射非线性系统模型,推导出了其输入输出反馈精确线性化非线性反馈控制律,实现三相并联型有源电力滤波器有功补偿电流和无功补偿电流的解耦控制器设计。最后使用Matlab进行仿真验证,仿真试验结果表明,该控制策略能较好地实现APF的解耦控制,具有较好的补偿特性,经该控制算法补偿,谐波畸变率限制在2%以下。  相似文献   

9.
为实现电网电压不平衡时对T型三电平光伏并网系统输出功率和电流质量的控制,以达到入网功率平稳或电流正弦为控制目标,结合光伏阵列输出功率前馈,在两相静止坐标系下提出一种直流母线电压外环PI控制、并网电流内环有限集模型预测控制的控制策略,并在电压外环中引入2倍频陷波器以获得平滑的入网功率参考值。仿真结果表明:当电网电压不对称时,采用所提控制策略能够实现对入网有功、无功功率2倍频脉动及负序电流的分别抑制或协调控制,且并网电流谐波畸变小、入网电能质量高,同时实现T型三电平逆变器的中点电位平衡。  相似文献   

10.
为有效改善长管道GIS互感器检定平台电源的电能质量,应用并联型APF补偿其中的谐波及无功,采用一种新型电流控制策略,直接检测网侧电流,电流控制环节采用PI控制器和谐振控制器分别作用于基波和谐波分量,用多个并联的谐振控制器根据补偿要求灵活设置谐波分量的补偿阶次,选择性补偿负载谐波,有效提高了并联型APF的补偿精度。最后,通过仿真及试验研究证明了该控制方法能有效降低谐波含量、提高电源的电能质量,具有重要的理论意义和使用价值。  相似文献   

11.
基于传统直接功率控制的策略思想,改变以L电感并人电网的拓扑结构,提出基于LCL滤波器的直接功率控制,系统分析有源阻尼,谐波抑制,虚拟磁通估计和锁相环PLL等控制算法,进而提出改进的直接功率控制策略。在MATLAB/SIMULINK的仿真平台上,分别搭建光伏并网的主电路模型。以及包含有源阻尼,谐波抑制,虚拟磁通估计和PLL模块的统一协调的控制系统,仿真结果表明改进的直接功率控制能有效改善并网逆变器的电流质量,降低总谐波畸变率,并使电网电压和注入电网电流同相,功率因数为1。  相似文献   

12.
A novel and simple i freal control algorithm using digital signal processor (DSP) has been proposed and realized for a three phase shunt active filter (SAF). The simulation and prototype construction of SAF is conducted to compensate the reactive power and harmonics in a distribution system. The major feature of the proposed i freal algorithm is that it does not require unit vector templates and any transformations for the reference current generation of SAF. This reduces the computational complexity and makes the control flexible and faster. The simulation is conducted in MATLAB/SIMULINK while DSP TMS320LF2407 is employed in the digital implementation of hysteresis current control (HCC) for experimentation. The hardware results correlate with the simulation results in reducing the total harmonic distortion (THD) of the source current and achieving unity power factor.  相似文献   

13.
三相逆变器数学模型的非线性特性加大了控制器设计的难度,为解决状态反馈精确线性化控制理论对三相逆变器非线性控制稳态性能较差的问题,设计了一种增广反馈的非线性控制策略,并利用LQR方法对控制参数进行了最优求解。仿真和试验结果表明,逆变器的电压瞬态变压范围应小于±5%,恢复时间小于0.04s;总谐波畸变率小于2%,单次谐波畸变率小于1%,该控制策略具有良好的动态、稳态性能。  相似文献   

14.
针对光伏并网逆变器的特点,基于电感电流反馈控制的光伏并网逆变器,提出了参考电流相位超前的电流内环控制策略。通过分析单相并网逆变器结构,推导了LC滤波器上电压电流矢量关系。加入电网电压瞬时值前馈解耦控制,研究了比例调节和准比例谐振调节两种策略下参考电流与输出电流的关联。基于一台3 kW逆变器为实验平台的理论分析和实验结果表明,采用该策略的逆变器并网电流时刻跟踪电网电压频率和相位,功率因数为1,并网电流谐波失真度低于3%。  相似文献   

15.
This paper is proposed to establish an optimal control method for UPQC (Unified Power Quality Conditioner) to improve power quality and manage effectively equal power sharing between shunt and series inverter of UPQC under electrical faults condition. The UPQC is modeled to protect sensitive load from source side voltage disturbances under nonlinear load conditions. A hybrid power generator that integrates a proton exchange membrane fuel cell (PEMFC) as the main energy source and a super capacitor (SC) as secondary source is proposed to feed the FACT device. In this work, a new control strategy is presented for considering the voltage sag, power factor and total harmonic distortion (THD) as multi-objective of UPQC controller. For this purpose, a new powerful algorithm named virus colony search (VCS) is used for determining the coefficients of the PI controller of UPQC. By using the fuzzification process for the objectives function, a suitable fitness function is established for the optimization method. From the simulations, it can be seen that the results obtained by the proposed algorithm are best and attractive compared to other method. Consequently, the proposed strategy is effective and outstrips other strategies.  相似文献   

16.
The harmonic distortion caused by a solid state AC voltage controller of an induction motor drive is evaluated. A conventional shunt harmonic filter (SHF) for harmonic reduction for a group of such drives is compared with a harmonic blocking compensator (HBC). It is shown that the HBC is more efficient in harmonic reduction than the SHF, especially, with distorted supply voltage. Moreover, the designer has more control over the HBC than the SHF performance. The HBC, however, has a higher power rating than the SHF  相似文献   

17.
针对电网电压畸变造成并网电流低频次谐波含量较高的问题,提出一种基于比例积分-准谐振(PIR)与电流谐波检测环相结合和控制策略抑制电流谐波。首先分析并网逆变器原理,建立电流内环数学模型。基于内模原理,引入电网电压全前馈消除电网电压对网侧电流和影响,其次分析电流谐波检测与抑制原理,采用电流特定次谐波检测环对逆变器侧电流提取谐波分量,并采用闭环控制抑制电流谐波,利用伯德图对准谐振控制器参数进行设定。最后建立Matlab/Simulink仿真模型并搭建dSPACE-DS1104半实物仿真平台,分析仿真与实验结果来验证所提控制策略和有效性与可行性。  相似文献   

18.
The energy use of the world grows continuously and the development of a clean distributed power generation becomes environmentally important. Fuel cells are one such integral part of Renewable Energy Sources based clean energy supply; that they operate with hydrogen as fuel and water with heat as process waste. Due to the electrochemical reaction, fuel cell has the power quality of delivering low voltage with high current capability. Here an attempt is made to develop a power conditioner with a series of conversion to get a 220 V sinusoidal AC, 50 Hz single phase voltage of low distortion and fast dynamic regulation to cater load variations. A novel Polyphase Boost DC-to-DC switching converter based on parallel connection of 8 identical converters with current mode control is devised to have minimum reflected ripple current and voltage injected to fuel cell input. A full bridge converter with high frequency transformer isolation, step-up the DC voltage level from the low voltage fuel cell along with poly phase boost converter, deliver required DC to the PWM inverter, which generate AC utility power output. Recent trend of Ultra-capacitor based transient energy storage and retrieval system, to cater for the sluggish behavior of fuel cell, for load transients is incorporated. DSP and FPGA based digital real time controllers are used to realize the gating of MOSFETs and IGBTs used in the power conditioner. A 1 kW power conditioner is developed for a PAFC fuel cell system with 12 V DC nominal and their performance evaluations are satisfactory.  相似文献   

19.
This paper proposes a high performance single-stage inverter topology for the autonomous operation of a solar photovoltaic system. The proposed configuration which can boost the low voltage of photovoltaic (PV) array, can also convert the solar dc power into high quality ac power for driving autonomous loads without any filter. An MPPT circuit with parallel connection is implemented so that the part of the energy generated is processed by the dc–dc converter to supply dc loads. The line current total harmonic distortion (THD) obtained using this configuration is quite reasonable. The proposed topology has several desirable features such as low cost and compact size as number of switches used, are limited to four as against six switches used in classical two-stage inverters. In this paper analysis, simulation and experimental results are presented.  相似文献   

20.
沙德尚  孔力  孙晓 《太阳能学报》2004,25(2):227-231
燃料电池电压输出范围比较宽,电压比较低。针对该特点本文设计了DC/DC和DC/AC两级变换的功率调节系统(PCS)。其中DC/DC将燃料电池输出的低压直流电高频变换成高压直流电,变换器为电压单环控制。DC/AC逆变器采用基于电压电流瞬时值反馈的双闭环控制,将高压直流电逆变为正弦交流电。分析了整个功率调节系统的工作原理及逆变器电路参数对稳定性的影响。0.5KVA佯饥实验结果表明整个系统具有电压输入范围宽、变换效率高、输出波形THD小等优点。为开发高效、高功率密度的燃料电池电源系统提供技术基础。  相似文献   

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