Voltage Unbalance Mitigation in Low Voltage Distribution Networks with Photovoltaic Systems

This paper proposes a technique to mitigate the voltage unbalance issue caused by the high penetration of photovoltaic(PV) systems into the low voltage distribution networks(LVDN) using a single phase energy storage system(ESS).The ESS comprises a bi-directional power flow inverter and a battery bank.The system is capable of absorbing the excess power and delivering power to the network in order to keep the voltage unbalance factor(VUF) below the statutory limit of 1%.Investigations are carried out in the experimental small-scale energy zone(SSEZ).The experimental results demonstrate that the ESS is capable of mitigating the VUF of the network.     

光伏并网逆变器电压型控制技术研究

本文主要对电压源电压型并网控制技术进行了研究.根据逆变器并联运行中的无功调幅.有功调频的控制原理,将此方法应用到光伏并网逆变器中实现了有功和无功的独立控制.使得逆变器在输出功率上控制更加灵活详细讨论了电压型并网控制算法,并给出了关键模块I_(d)、I_(q)。的计算方法和正弦波合成器的实现过程最后.在Matlab/Simulink中建立了仿真模型,并进行了实验验证.仿真和实验结果表明电压型并网控制方案具有可行性。     

宽电压输入智能光伏充电控制系统

设计一款具有最大功率点追踪功能的宽电压输入智能光伏充电控制系统。系统采用恒压法和小步长扰动观察法相结合的方式,实现最大功率点的跟踪控制,通过对充电电压、充电电流及蓄电池表面温度的检测,智能地选择快速脉冲充电、浮充充电、自动停止充电等工作模式,使充电过程始终处于安全状态。实际运行结果表明：该系统可在5～26V的输入电压范围内正常工作,充电过程精确可控。     

基于电压直接控制的光伏系统最大功率点跟踪策略

在分析光伏系统的数学模型和输出特性的基础上,对传统的扰动测量法进行了改进,提出一种直接基于太阳能输出电压的最大输出功率点跟踪策略。利用Simulink对该方法进行仿真,并且应用到实际光伏系统中。测量结果表明了方法的优越性,能够适应天气变化较快的场合,输出功率能够快速跟踪太阳能最大功率点。     

Continuous Chopper-Based Voltage Regulation for Power Transformers

This paper presents a procedure to regulate the voltage of power transformers in a continuous manner. The proposed system combines a minimum number of solid-state switches with conventional magnetically coupled windings in such a way that currents and voltages applied to semiconductor devices constitute only a small fraction of the rated values, which leads to reduced cost, losses and harmonic distortion. An added advantage lies in its modularity, allowing the main transformer to remain in service at nominal constant voltage in case of failure of the electronic module.     

光伏并网对配网电压影响的PSCAD仿真与分析

讨论了光伏电池的基本工作原理和主要电气参数,PSCAD仿真软件中无光伏阵列仿真元件,根据光伏阵列的数学模型,利用PSCAD自行搭建了自定义的光伏阵列控制元件,来模拟实际的光伏阵列控制装置.基于PSCAD仿真平台搭建了光伏并网模型,通过仿真模型分析了光伏并网对配网电压的影响.     

Modeling the Effect of Voltage Ripple on the Power Output of Photovoltaic Modules

This paper proposes a model for the static power loss in photovoltaic (PV) panels due to switching-frequency ripple. Small-signal modeling is used to determine the amplitude of the voltage ripple that is imposed on the PV panel, and a closed-form expression is developed for the output power. The expression is shown to be more accurate than the power loss that was predicted by small-signal modeling alone, resulting in a median error of 0.8%. The model presented allows dc-dc converter designers to more precisely choose the input filter components that are critical during times of low insolation.     

基于多线程的光伏电池电压数据采集系统的实现

多线程技术可以并发执行多个任务。单片机对光伏电池的开路电压进行A/D转换后,将数据发送到PC机串行口;监视线程监视串行口并向主线程发送消息,主线程调用函数处理。为使数据正确识别在发送、接收端应规定双方都能解读的数据结构,为使数据完整读取在监视线程的消息发送和主线程的消息处理函数之间应保持同步。实验表明设计正确,程序运行正常。     

深亚微米处理器电压调节走向数字化

处理器与电源之间性能差距的日益扩大是一个威胁到系统性能进一步全面提高的严重问题。处理器沿着摩尔定律不断发展,其应用的复杂程度呈现指数型的增长,致使上述问题变得越来越严重。越来越多的芯片制造商和系统OEM(原型设备生产商)逐渐地认识到电源性能改进的迫切性和重要的战略意义。许多分析工业技术发展趋势的文章已经明确指出了这个问题的严重性,即处理器电源的性能远远落后于处理器本身,这将会严重阻碍今后的发展。Intel公司的首席技术官PatGelsinger,最近在开发者论坛上就电源问题发表看法。他说:“我们预测摩尔定律在今后十年将…     

用于电压或电流调节的新调节器架构

一种新的调节器架构为分散热量和电流调节提供了解决方案。这些新的调节器具有优于从前器件的性能。     

Multilevel Diode-Clamped Converter for Photovoltaic Generators With Independent Voltage Control of Each Solar Array

In photovoltaic (PV) power systems where a set of series-connected PV arrays (PVAs) is connected to a conventional two-level inverter, the occurrence of partial shades and/or the mismatching of PVAs leads to a reduction of the power generated from its potential maximum. To overcome these problems, the connection of the PVAs to a multilevel diode-clamped converter is considered in this paper. A control and pulsewidth-modulation scheme is proposed, capable of independently controlling the operating voltage of each PVA. Compared to a conventional two-level inverter system, the proposed system configuration allows one to extract maximum power, to reduce the devices voltage rating (with the subsequent benefits in device-performance characteristics), to reduce the output-voltage distortion, and to increase the system efficiency. Simulation and experimental tests have been conducted with three PVAs connected to a four-level three-phase diode-clamped converter to verify the good performance of the proposed system configuration and control strategy.     

分布式光伏发电孤岛运行中的有功-电压特性分析

文章首先分析了分布式光伏发电孤岛运行的机理,得出了分布式光伏发电系统孤岛运行时的有功-电压运行特性,并对该特性进行了试验验证.该运行特性的提出,可为分布式光伏发电反孤岛策略、离网系统的能量管理等提供依据.     

带中性点电压调节的级联型高压变频器拓扑研究

目前传统级联型高压变频器广泛应用于交流电机的调速,但是结构上的缺陷使得它无法将电机制动能量回馈至电网。本文提出了一种具有能量回馈功能的级联型高压变频器新型拓扑。在传统级联高压变频器拓扑的基础上,将浮空的中性点断开,串入一个双PWM变换器．并对串入的双PWM变换器建模,最后通过仿真验证,说明这种新型拓扑在电机制动时进行能量回馈的可行性。     

基于电网电压矢量定向的双闭环光伏并网逆变系统的研究

针对传统光伏系统并网逆变技术的问题,提出了一种新型的基于电网电压矢量定向的双闭环直接电流控制技术,依据系统动态数学模型构造了直流电压外环和有功、无功电流内环控制系统,同时采用SVPWM技术控制IGBT的通断,实现了光伏并网逆变系统精确的运行在单位功率因数状态。最后,通过对比分析MATLAB仿真与以DSP为控制芯片搭建的两级非隔离式光伏并网逆变系统实验,验证了所提算法的正确性。     

用于原边反馈式反激变换器的电压采样电路

提出了一种应用于原边反馈式反激变换器的电压采样电路。该电压采样电路通过三路依次采样,在不同模式下使用对应的算法,得到最接近真实值的采样值。仿真结果表明,在采样频率10 MHz的条件下,该电压采样电路在CCM和DCM模式下均能正常工作,在DCM模式下的误差可低至0.8%。     

恒流-恒压模式控制的锂电池充电器的设计

设计了一款恒流-恒压充电模式控制的锂离子电池充电器,当电池电压低于2.9 V时,充电器提供涓流充电模式;当电池电压高于2.9 V时,充电器提供恒流充电模式;当电池电压达到4.2 V时,实现恒压充电模式对充电器的控制,充电电流减小。对主要子模块的电路进行了详细的设计与仿真并进行了稳定性分析,均能够在不采用任何补偿的情况下保持稳定。电路采用CSMC公司的0.6μm B iCMOS工艺模型,基于Cadence仿真平台对电路进行了前仿真,仿真结果表明,在5 V电源电压下,涓流充电电流为50 mA,恒流充电电流为502 mA,最终电池电压为4.202 V。     

Power Injection System for Grid-Connected Photovoltaic Generation Systems Based on Two Collaborative Voltage Source Inverters

This paper presents a new topology for the power injection system that is based on the parallel association of two voltage source inverters. One operates using a quasi-square voltage waveform strategy, and the other operates with a pulsewidth-modulation (PWM)-based strategy. The aims of this topology are to inject the power from the photovoltaic generation system using the quasi-square inverter and to control the current quality using the PWM inverter. The proposal optimizes the system design, permitting the reduction of system losses and an increase of the energy injected into the grid.     

High Fill Factor and Open Circuit Voltage in Organic Photovoltaic Cells with Diindenoperylene as Donor Material

Small‐molecule photovoltaic cells using diindenoperylene (DIP) as a new donor material in combination with the fullerene C₆₀ as an electron acceptor are demonstrated. In addition to the successful application in planar and bulk heterojunction devices, a comprehensive analysis including structural studies, the determination of the energy level alignment and electrical transport investigations is given, stressing the correlation between growth conditions, film morphology, and device performance. Due to pronounced crystallinity and a large surface area of DIP films grown at elevated temperature, exceptionally high fill factors of almost 75% are achieved in planar heterojunction cells. Bulk heterojunctions exhibit large‐scale phase separation forming a bicontinuous network of both molecular species, which enables efficient exciton dissociation and charge carrier transport. The high ionization potential of DIP and the favorable energy level alignment with the fullerene C₆₀ yield large open circuit voltages close to 1 V and comparable power conversion efficiencies of about 4% in both cell architectures.     

Design and Analysis of Output Voltage Regulation in Multi-Phase Switched Capacitor Converters

A new regulation method based on duty cycle control of the average currents in the multi-phase switched capacitor converters (SCC) is proposed, analyzed, and verified experimentally for the no effective charging case, also known as the fast switching limit. The regulation is accomplished by adjusting the value of the SCC equivalent resistance. To this end, the time slots allotted to each of the SCC topologies are adjusted, while the total switching period is kept constant. The time slots are represented by master and slave duty cycles. By this, the SCC output voltage is expressed analytically as a function of the master duty cycle. In a similar way, analytical expressions for the voltages across the flying capacitors and for the average currents in each of the topologies can be obtained. Excellent agreement was found between the theoretical and experimental results.     

NCV8501和NCV8502系列芯片在车用电源中的应用

NCV8 5 0 1和NCV85 0 2系列精密微功率稳压器为车用电源提供了监控功能 ,具有更宽温度范围内的低静态电流 ,输出电压可调 ;具有防电池反接、防短路和防热过载流子等情况的保护功能 ,能承受 6 0V尖峰瞬态电压 ,防止“负载倾卸”情况下造成的损害