基于光伏并网的功率控制算法研究

针对光伏并网发电系统中的逆变器工作具有间歇性和容量利用低的情况,提出了一种改进型的光伏并网功率控制算法。该方法不仅能够向电网和本地负载提供有功功率,而且能补偿电网中的无功和谐波。该方法由谐波和无功电流检测、给定电流信号合成、电压电流双闭环和功率前馈构成。通过改进传统光伏并网功率控制系统中的电流给定算法,使系统能够根据天气和电网电能质量的状况进行工作状态的切换。提出后级网侧逆变器直流电压外环控制结合光伏电池输出功率前馈控制策略,解决了天气突变可能造成直流母线电压波动的问题。通过仿真的对比研究,证明了所提出方法的可行性。     

基于低电压穿越的光伏发电系统控制研究

随着并入电网中光伏电站容量的增加，为保证电力系统的稳定运行，要求光伏电站在电压跌落期间不脱网运行，以两级式光伏发电系统为研究对象，在传统并网控制的基础上，研究了光伏发电系统低电压穿越控制策略。电网电压跌落时，为抑制直流侧过电压，应降低光伏阵列输出功率，前级光伏阵列+Boost电路由MPPT控制转为限功率控制；同时，为抑制交流侧过电流，后级DC/AC电路电压外环断开，重新分配电流内环有功和无功电流参考值，采用基于无功支撑的控制策略。通过仿真对比分析验证了控制方法的可行性。     

光伏并网逆变系统的MATLAB仿真研究

光伏并网发电系统是光伏发电系统发展的趋势。单极式光伏并网逆变系统具有拓扑结构简单，成本较低的有点。这种系统中只存在一个能量变换环节，太阳能最大功率点跟踪（MPPT），电网电压同步等控制目标需要考虑。本文介绍了单极式光伏系统的拓扑结构和实现最大功率的工作原理．阐述了电导增量法实现MPPT的基本思想。根据光伏系统并网发电拓扑结构，设计了一套新型的实现最大功率跟踪的单极式光伏并网逆变器，逆变器控制部分由DSP实现最大功率跟踪和输出电流跟踪控制，实现了逆变输出电流与电网同步，且高功率因数运行。仿真和实验结果表明，单极式光伏并网逆变系统能准确跟踪太阳能电池最大功率点，并具有较好的稳定性。     

无功与谐波补偿检测的光伏并网仿真研究

研究了光伏电源并入配电网后对电能质量的影响.从理论上分析了对光伏并网发电系统进行无功补偿和消除配电网谐波的方法,利用瞬时无功功率理论检测系统无功及谐波电流,将无功和谐波补偿策略与光伏发电控制相结合.仿真结果表明,光伏电源并网能够较好地补偿系统无功和负载谐波,对提高负荷特性和电网的电能质量、减小电网电流谐波有显著的效果.     

三相电压型光伏并网装置控制策略的研究

随着传统能源的日益枯竭,太阳能无疑是极具发展潜力的新能源.光伏发电(太阳能)可分为独立供电和并网发电两种;重点研究三相光伏并网系统的控制策略,阐述了利用电网电压前馈补偿以及电流跟踪技术并网的原理,针对单级式光伏并网发电(此结构的特点就是效率高,但必须在一个功率变换环节实现升压、最大功率跟踪、DC/AC逆变,控制相对复杂),利用d-q变换,得到了一种有功功率和无功功率分别独立进行控制的方法;最后通过建立相关的MATLAB控制模型进行仿真,实现了网侧电流的正弦化及单位功率因数,验证了设计的正确性.     

基于电网电压定向的光伏并网逆变器系统研究

针对传统的光伏并网系统逆变控制策略存在控制复杂、谐波含量多的问题,提出了一种基于电网电压定向的光伏并网逆变器直接电流控制方法,给出了以TMS320F2812为主控制器的三相光伏并网逆变器系统的硬件及软件设计。该逆变器直接电流控制方法采用过零检测电路测量电网电压的过零点时刻,得出过零点时刻的电网电压的旋转角度,从而得到逆变器输出电压的幅值和相位;采用SVPWM技术控制IPM的开断,使逆变器输出上述幅值和相位的电压,从而实现单位功率因数并网发电功能。实验结果表明,该逆变器直接电流控制方法简单,逆变器输出电流与电网电压基本保持相同的频率和相位,并网发电功率因数接近于1。     

具有谐波抑制与无功补偿功能的光伏并网系统

介绍了一种新型的光伏并网发电系统模型,在并网发电的同时实现了对电网中的无功和谐波的补偿与抑制。基于光伏阵列的等效电路模型,在Matlab仿真环境下,建立光伏阵列的通用仿真模型。利用该模型,设计新型的光伏并网发电系统。该系统将光伏并网系统的发电控制和无功补偿、有源滤波相结合,使得光伏并网发电系统不仅可以并网发电还具有谐波抑制与无功补偿的功能,进而提高电网的供电质量和能力。最后对该系统进行仿真实验验证,仿真结果验证了系统模型的正确性和有效性。     

非理想电网下多电平并网逆变器控制仿真

在非理想状态下，多电平并网逆变器正负序电压影响，控制精确度下降，提出非理想电网下多电平并网逆变器控制研究。在非理想电网情况下，构建3L-ANPC光伏并网逆变器数学模型，计算三相电网电压、电流、正序分量、负序分量、谐波分量等，通过对称分量法分离正负序电压，通过锁相环定向正负序分量，利用派克变换锁相三相电流电压，实现多电平并网逆变器控制。实验使用Matlab仿真软件构建3L-ANPC光伏并网逆变器仿真模型，实验结果表明：可有效控制交流侧a相电压在-50-50V范围、电流在-1～1A之间，抑制谐波能力较好；在电压出现波动时受影响较小，上述方法可维持电压稳定输出；可显著抑制有功功率和无功功率波动。     

基于解耦锁相的风电逆变并网控制系统仿真

采取双同步坐标系解耦锁相的方法,检测出不平衡电网电压中的正序分量和负序分量,并利用坐标变换的数学手段建立包括网侧PWM 逆变控制、电压锁相环在内的直驱式风力发电的网侧数学模型,提出电流解耦控制策略,同时结合矢量脉宽调制方法( SVPWM) 对交流侧输出电流实施有效控制。使其能独立控制输出电流的有功分量和无功分量,并使输出电流波形为正弦波且与电网电压同频率同相位,从而减少了对电网电压的谐波污染,并消除电压不平衡的影响,实现三相电网电压幅值不平衡时输出电流与电网电压的精确锁相。还利用MATLAB/Simulink 软件平台搭建了系统的仿真模型,在电网电压平衡和不平衡时分别进行仿真,仿真结果证明控制系统的可行性与有效性,提高了风力发电并网的可靠性。     

分布式光伏发电并网数字化建模与仿真北大核心

为了改善光伏发电性能,需要对分布式光伏发电并网控制技术进行研究。提出基于MPPT控制的分布式光伏发电并网建模方法,建立光伏电池模型,在所建模型的基础上研究光伏发电系统输出功率受光照强度变化的影响。并利用MPPT控制方法跟踪分布式光伏系统的最大功率点,提高分布式光伏系统在运行过程中的输出功率。通过滑膜控制对光伏并网逆变器进行控制,保持电网电压与光伏发电系统输出电流的同步性,实现分布式光伏系统并网发电。通过仿真,验证了所提方法可有效地实现光伏阵列最大输出功率的跟踪,满足分布式光伏发电并网系统的运行要求。     

Simulation modelling and analysis of modular cascaded multilevel converter based shunt hybrid active power filter for large scale photovoltaic system interconnection

Modular multilevel inverters are promising candidates for next generation of efficient, robust and reliable inverters in large scale photovoltaic system. A modular cascaded multilevel inverter based shunt hybrid active power filter (SHAPF) for three phase grid-connected large scale PV systems is represented in this paper. The main contribution of this paper is to model and control of grid interfaced large scale photovoltaic system with embedded hybrid active power filter functions. In proposed system, the features of hybrid active power filter have been amalgamated in the control circuit of the voltage controlled voltage source inverter interfacing the photovoltaic system to the grid. As a result, the same inverter part of SHAPF is utilized to inject power generated from photovoltaic source to the grid and also to act as hybrid active power filter to compensate harmonics and reactive power demand. With using compensation ability, the grid currents are sinusoidal and in phase with grid voltages. The whole system is modeled in PSCAD/EMTDC. The simulation results are demonstrated to verify the operation and the control system of the proposed system.     

独立、并网双模式户用光伏发电装置的研究与设计

针对户用光伏发电系统的特点和要求进行了系统的研究与设计。系统设计将独立逆变与并网逆变相结合,使系统既可以工作在独立逆变状态,为负载提供正弦交流电源,也可以工作在并网逆变状态,将太阳的能量或蓄电池的能量回馈到电网。本系统采用TI公司32位定点DSP芯片TMS320F2812为控制核心,利用PIC16F877A单片机构成系统的人机操作界面。本文所设计的系统具有完善的保护功能、键盘监控和液晶显示、串口通讯功能,为家庭使用提供了方便。实验结果验证了方案的可行性。     

新型MPPT算法在光伏并网系统中的应用

光伏并网系统在天气急剧变化时,采用传统的最大功率跟踪算法会产生较大误判,不仅造成电池板功率的损失,而且还会导致并网电流的畸变。针对这一问题,对传统扰动观察法进行了改进,提出了一种新型MPPT算法,有效地防止了功率误判。将此新型算法配合电压电流双环控制应用于光伏并网系统。从仿真结果看到,在光照突变和电网电压扰动时,并网电流均能够快速跟踪电网电压的相位和频率。表明了新型算法的正确性和有效性。     

基于NSGA-II的并网型风光互补发电系统协调控制

针对并网型风光互补发电系统中,系统最大输出功率大于给定功率时,风力发电子系统和光伏发电子系统功率如何协调的问题,提出了一种功率协调控制方法.在该方法中,根据系统并网收益最大和输出电流谐波最小构建目标函数,采用带精英策略的快速非支配排序遗传算法对风力发电子系统和光伏发电子系统的输出功率进行多目标优化,协调控制子系统的发电功率;并以甘肃华电阿克赛风光互补发电项目为例进行了仿真验证.仿真结果表明,与传统的光伏优先接入方式相比,基于NSGA-Ⅱ的并网型风光互补发电系统协调控制方法可以更加合理地利用风能和太阳能,提高新能源电能的电网友好性.     

Stable reactive power balancing strategies of grid‐connected photovoltaic inverter network

In this paper, a distributed reactive power control based on balancing strategies is proposed for a grid‐connected photovoltaic (PV) inverter network. Grid‐connected PV inverters can transfer active power at the maximum power point and generate a certain amount reactive power as well. Because of the limited apparent power transfer capability of a single PV inverter, multiple PV inverters usually work together. The communication modules of PV inverters formulate a PV inverter network that allows reactive power to be cooperatively supplied by all the PV inverters. Hence, reactive power distributions emerge in the grid‐connected PV inverter network. Uniform reactive power distributions and optimal reactive power distributions are considered here. Reactive power balancing strategies are presented for both desired distributions. Invariant sets are defined to denote the desired reactive power distributions. Then, stability analysis is conducted for the invariant sets by using Lyapunov stability theory. In order to validate the proposed reactive power balancing strategies, a case study is performed on a large‐scale grid‐connected PV system considering different conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

Distributed generation system control strategies with PV and fuel cell in microgrid operation

Control strategies of distributed generation (DG) are investigated for different combination of DG and storage units in a microgrid. In this paper the authors proposed a microgrid structure which consists of a detailed photovoltaic (PV) array model, a solid oxide fuel cell (SOFC) and various loads. Real and reactive power (PQ) control and droop control are developed for microgrid operation. In grid-connected mode, PQ control is developed by controlling the active and reactive power output of DGs in accordance with assigned references. Two PI controllers were used in the PQ controller, and a novel heuristic method, artificial bee colony (ABC), was adopted to tune the PI parameters. DGs can be controlled by droop control both under grid-connected and islanded modes. Droop control implements power reallocation between DGs based on predefined droop characteristics whenever load changes or the microgrid is connected/disconnected to the grid, while the microgrid voltage and frequency is maintained at appropriate levels. Through voltage, frequency, and power characteristics in the simulation under different scenarios, the proposed control strategies have demonstrated to work properly and effectively. The simulation results also show the effectiveness of tuning PI parameters by the ABC.     

具有谐波补偿功能的光伏并网逆变器控制策略研究

随着高新能源技术的发展,光伏并网发电在通过逆变器并网时往往会产生大量的不同谐波,并因此消耗大量的电能。接入电网的光伏并网逆变器中存在大量的负载,这将使整体电网质量下降。针对此问题,论文提出一种具有谐波补偿功能的光伏并网逆变器控制方法,通过谐波补偿装置采集电网中的谐波含量,并基于MPPT算法对所采集的谐波进行分析、计算,根据所计算出的分析结果补偿谐波。该技术方案在三相电和单相电情况下均可正常使用。通过在实验室Matlab/Simulink环境下建立系统拓扑构架进行试验,电网中的电流谐波含量大大降低,从而消除了电网谐波对负载光伏并网逆变器的影响,因此,仿真结果验证了理论分析,该技术方案具有一定的实用价值和科研价值。     

基于GAHP的并网光伏电站电能质量评估

根据国家电网公司光伏电站接入电网规范对各电能质量指标的要求,本文提出了一种基于GAHP的并网光伏电站电能质量评估方法。广集多位利益相近的专家意见,得到电能质量中各指标的综合权值;将各指标的有效范围划分成五个等级,统计并网光伏电站的实测数据属于这些等级中的概率,以此作为客观权重。综合GAHP方法的主观权重和实测数据的客观权重,全面地对并网光伏电站电能质量进行了评估,为光伏电站的并网运行提供一定的决策依据。     

并网系统逆变器锁相环的研究

在太阳能光伏发电系统中,并网逆变器是实现光伏电能馈送电网的重要环节,并网光伏逆变器的控制目标为：控制逆变电路的输出为稳定的、高品质的正弦波,且与电网电压同频、同相。鉴于此,本文提出了一种数字电流锁相的方法,并且进行了系统仿真。仿真结果表明,TMS320C2000系列DSP芯片适用于该数字锁相技术,其并网输出电流波形良好...     

Investigations of an improved PV system topology using multilevel boost converter and line commutated inverter with solutions to grid issues

A photovoltaic (PV) system using multilevel boost converter (MBC) and line commutated inverter (LCI), operating in both grid-connected mode and stand-alone mode has been analysed. This proposed system extracts and feeds the maximum power to a single phase utility grid and stand-alone system simultaneously. The duty ratio of the MBC is estimated from the theoretical analysis of the proposed system, for extracting maximum power from PV array. The proposed system tracks the maximum power with the determined duty ratio which remains the same for all irradiations, for a fixed firing angle of LCI. The flexibility of supplying required proportion of extracted power to grid and stand-alone load and the elimination of a separate MPPT controller are the major benefits of the proposed system under normal grid conditions. In addition to it, the grid issues like voltage swell, blackout and brownout are considered and necessary remedial measures have been taken in the proposed system. Based on the issues, either the firing angle of LCI is adjusted or LCI is disconnected and replaced by a battery. Simulation studies have been carried out and the dynamic response of the system is observed. A laboratory prototype is built and experimental investigations have also been carried out. The theoretical analysis, simulation and experimental results are found to be closely associating with each other proving the efficacy of the proposed configuration.