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。     

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.     

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.     

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.     

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。     

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.     

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。     

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.     

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.     

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。     

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.     

用于电压调节器的PZST反铁电陶瓷研究

通过调节Zr^4＋／Ti^4＋比对La^3＋、Sr^2＋掺杂的PZST反铁电陶瓷进行分析，从中得到两种能用于电压调节器件的陶瓷材料。在20～80℃时，这两种材料的相变电场随温度变化不大。材料的反向开关时间为1～12μs，开关时间随反向相变电场的升高而减小，且与样品的尺寸有关。     

多级拼波调压节能技术在钟罩炉上的应用

钟罩式气氛烧结炉是一种炉体为升降式的烧结炉。由于钟罩炉功率较大,因此耗电量大。节能降耗对于钟罩炉的使用具有很好的实际意义。介绍了多级拼波调压技术在钟罩炉温控系统的应用,取得了较好的节能效果。     

Analysis Results of Output Power Loss Due to the Grid Voltage Rise in Grid-Connected Photovoltaic Power Generation Systems

This paper describes the connected photovoltaic (PV) power generation system's grid overvoltage protection function and summarizes the occurrence of the output power loss due to the grid voltage rise. Power injection from the PV system will raise the voltage at the power distribution line. A power conditioning subsystem (PCS) needs to regulate its output if the voltage becomes higher than the upper limit in order to avoid the overvoltage at the power grid. Thus, a PV system cannot generate electricity under the high grid voltage. There are 553 residential PV systems installed in Ota, Japan, for the demonstration research project of clustered PV systems. Measurement data of these 2.1-MW grid-connected PV systems are used for the analysis. Only the limited number of PV systems experienced a significant amount of output energy loss due to the high grid voltage in a particular day, whereas the other system's outputs also raise the grid voltage. The causes of this maldistribution of the output energy loss are the difference of the line impedance, the difference of the starting voltage of the PCS's grid overvoltage protection function, and the imbalance of the load in single-phase three-wire power distribution systems. The present control of the PCS successfully avoids the overvoltage on the grid but cannot share the loss.     

Distributed Control for UPS Modules in Parallel Operation With RMS Voltage Regulation

A novel distributed control for uninterruptible power supply (UPS) modules in parallel operation is proposed in this paper, in which the voltage reference synchronization control and load current distribution control are decoupled by a local feedback. The voltage reference is presynchronized beyond the current distribution control with a microcontroller unit and a wired-and circuit. Both instantaneous current distribution and hot swapping of any module are allowed with all the UPS modules electrically isolated. The transfer function of the circulating current regulator is analyzed and equivalent to a first-order low-pass filter. The control characteristics of the root-mean-square voltage regulator (RMSVR) in each UPS module in parallel operation are researched, as well as the coupling effect between the RMSVR and the load balance performance. The RMSVR's impact on current distribution is compensated by introducing the amplitude of the output current or the circulating current into the amplitude adjustment of the sinusoidal voltage reference signal. As a result, both the current sharing and the output-voltage performance of the whole system are effectively improved. Theoretical analysis and experimental results are provided to demonstrate the validity and feasibility of the proposed control.