柴油发电机组建模及其带脉冲负载系统运行分析

脉冲负载逐渐成为电力负载的发展趋势,与传统负载不同,这类持续加卸载的突变型负载对于柴油发电机组等容量和惯性较小的冲击较大,易造成系统运行不稳定。分析柴油发电机组带雷达脉冲负载的系统结构,结合脉冲负载的工作特点对柴油发电机组结构进行细化考虑,建立柴油发电机组的数学模型。并在Matlab/ Simulink中搭建系统仿真模型,分析了脉冲负载工作时系统的运行情况,研究了系统的运行与脉冲负载功率PL、输出占空比D、和开关周期TS的关系。搭建了柴油发电机组带脉冲负载系统的试验平台,通过试验验证了所建模型能够较真实地反映系统的运行行为。     

柴油发电机组-脉冲负载系统运行行为仿真

柴油发电机组-整流器供电系统是重要的移动装备电源形式,可作为重要工程的备用电源,也可作为直流微电网的重要支撑电源。脉冲负载集成了大量电力电子器件,是一类功率波动明显且切换频繁的负载形式,以含大功率收发组件的数字式雷达为代表。在脉冲负载工作过程中,线路中电流与电压呈强烈非线性,系统动态过程复杂,难以运用解析方法表示柴油发电机组内部的机电过渡过程与电磁暂态。文中建立了基于Matlab/ Simulink 的系统模型,分析了脉冲负载在不同工作模式时,柴油发电机组输出电压与频率的瞬态和稳态指标,结果表明:该模型能够较真实地反映柴油发电机组-整流器-脉冲负载系统的运行行为。     

柴油发电机组带非线性负载的实验研究北大核心CSCD

柴油发电机组作为人防工程最主要的备用电源,其安全可靠性对于人防工程防护效能的发挥有着至关重要的影响,而人防工程的负载多为非线性负载,文中以带UPS电源的相控阵雷达为例,通过实验研究非线性负载对柴油发电机组供电质量的影响,分别测试UPS空载、水冷负载运行、发射机工作时,柴油发电机组输出电压电流波形及畸变率,并对实验结果进行讨论分析,提出了改善供电质量的方法。     

含脉冲负载独立微电网的柴-储协调控制策略

为研究含脉冲负载独立微电网的柴-储协调控制应用关键技术,首先通过仿真分析了不同控制策略的逆变器与柴油发电机组并联带混合负载的不同效果,根据不同控制策略下双源并联带不同类型负载的特点,结合含脉冲负载独立微电网的负荷特点,采用V/f控制、下垂控制、虚拟柴油发电机组控制的组合作为逆变器的控制策略。针对减少柴油消耗、增加可再生能源利用、优化系统运行状态的目标,研究了能量管理方案。最后以含脉冲负载独立微电网的多种电源配置为例,进行了效益分析。     

柴油发电机组带雷达脉冲负载暂态特性研究

脉冲负载逐渐成为电力负载的发展趋势,与传统负载不同,雷达脉冲负载的典型特征是平均功率小、峰值功率大。柴油发电机组由于容量和惯性较小,负载的频繁突变会造成系统运行不稳定。文中针对脉冲负载提出了电压相对偏差率的概念和计算方式,通过设置绝缘栅双极晶体管触发信号,模拟脉冲负载的工作周期和占空比,调节电阻大小模拟雷达脉冲负载的峰值功率,详细分析了脉冲负载下系统暂态特性。基于同步发电机-整流器系统,研究了雷达脉冲负载的占空比、工作周期、峰值功率、滤波电容变化时对系统动态指标的影响规律。     

基于Matlab的p-q法与ip-ip法仿真分析

针对p-q法和ip-iq法的谐波电流检测效果的比较,由于两种检测方法都是首先检测出原电流基波分量,再与原电流做差得到原电流谐波分量,因此可以通过计算检测出的基波电流中的谐波含量或畸变率来比较两种方法的检测性能.在接有非线性负载的系统中,通过控制电压源的电压波形,在(0.8-0.9)s时间段内产生标准正弦电压,在(0.9-1.0)s时间段内产生的畸变电压,利用p-q法和ip-ip法分别对同-检测点进行谐波电流检测.通过Matlab软件仿真试验,在(0.8-0.9)s时间段内利用p-q法和ip-ip法测得的基波电流的畸变率分别为1.72％和2.04％,在(0.9-1.0)s时间段内利用p-q法和ip-iq法测得的基波电流的畸变率分别为32.73％和4.39％.从而得出结论:在检测点处电压无畸变时,两种方法的检测性能都比较好,基波电流畸变率低,误差小;当电压发生畸变时,p-q法检测性能变差,基波电流畸变率变高,而ip-ip法检测性能无明显变化,适用范围更广.     

感应式无线电能传输系统谐波特性研究

感应式无线电能传输系统在超出一定负载范围时,将进入断续工作模式,基于基波近似法得到与负载无关的输出增益特性将不再满足,本文针对S-CLC型复合补偿拓扑,采用谐波分析法建立系统数学模型,给出整流侧电压/电流的谐波表达式,揭示波形发生畸变断续的主要原因。针对该补偿拓扑带载能力弱,提出了一种通过增加反向输入阻抗的高次谐波比例来提高输出增益的负载敏感度。搭建样机进行实验,结果验证了理论分析的正确性。     

脉冲密度调节谐振逆变器的功率控制技术

脉冲密度调节谐振逆变器主要优点在于调节负载功率的同时能够保证逆变器开关器件始终工作在零电压和零电流开关状态,整个运行过程都具有较高的负载功率因数和较低的谐波畸变率。然而,脉冲密度调节谐振逆变器的输出功率响应往往是离散和非线性的,这就要求找出一种控制策略能够实现可靠地负载功率调节。文中针对脉冲密度调节谐振逆变器提出了一种基于CycloneⅡ可编程门阵列的预期算法和滞环比较的实现方案。仿真实验结果表明这种控制方法能够在较大的范围内实现精确的功率调节。     

用于晶闸管过零触发的几种方式

目前晶闸管功率调整装置在诸如温度控制等场合,正在越来越多地被采用。过零触发则是在交流电压(电流)过零时触发晶闸管,负载上得到的是完整的正弦波电压(电流),克服了移相触发造成的负载电压(电流)波形畸变。因此,零触发交流开关的应用日益广泛。我们通过长期的生产实践,总结了一些如何取得过零触发脉冲的方法,现介绍如下。     

基于前馈电流控制斜坡补偿的Boost功率因数校正零交越失真研究

该文提出了一种前馈电流控制的斜坡补偿方法,将该方法引入到临界导通Boost 功率因数校正(PFC)转换器的设计中,以减小零交越失真问题,改善谐波电流和频率对系统的限制。基于临界导通Boost PFC转换器的拓扑结构,理论分析了前馈电流控制斜坡补偿技术对脉冲宽度调制(PWM)信号占空比的调制作用,推导出补偿斜率与输入线电压的关系式,迫使线电压零交越点附近的电流跟随电压变化。仿真和测试结果表明,该方法可有效抑制零交越失真现象,提高系统的动态性能,尤其在高频及轻负载情况下。测得Boost PFC转换器的总谐波失真(THD)仅为3.8%,功率因数0.988,负载调整率3%,线性调整率小于1%,效率达到97.3%。有效芯片面积为1.611.52 mm2。     

±60 kV三电极场畸变气体开关静态特性研究

在高功率脉冲Marx发生器中,气体开关具有连接储能器件与负载作用。文中为一种高能量输出、高频Marx发生器,设计了一种三电极场畸变气体开关。开关电极采用同轴结构,具有体积小、放电电流大和工作电压范围宽等优点;通过实验对不同气压和电极间距下场畸变气体开关电极静态特性进行了测试,实验结果表明,场畸变气体开关自击穿电压随SF6气压的增长从线性增长到非线性增长;工作电压范围随场畸变气体开关两主电极之间距离的增大而增大,最终趋于平缓;击穿电流和电压的分散性都随着工作气压的增大而增大。     

Dynamic and steady state analysis of a three phase buck rectifier

Current source rectifiers among other alternatives, offer several advantages over line commutated rectifiers. Advantages include displacement power factor control and reduced line current harmonic distortion. This paper analyzes the current source rectifier (CSR) in transient and steady state, the models are developed in a synchronous reference frame. The load behavior is characterized for two load conditions, resistive load or, in general, increasing current for increasing voltage, and constant output power, decreasing output current for increasing voltage. Constant power operation can occur for a converter system supplying a pulse width modulation (PWM) inverter with high dynamics. Several static converter characteristics such as power factor, real and reactive power are analyzed for both types of load. Transient characteristics are analyzed for both types of load by exact small-signal model with full set of equations     

An accurate approach of nonlinearity compensation for VSI inverter output voltage

An accurate nonlinearity compensation technique for voltage source inverter (VSI) inverters is presented in this paper. Because of the nonlinearity introduced by the dead time, turn-on/off delay, snubber circuit and voltage drop across power devices, the output voltage of VSI inverters is distorted seriously in the low output voltage region. This distortion influences the output torque of IM motors for constant V/f drives. The nonlinearity of the inverter also causes 5th and 7th harmonic distortion in the line current when the distributed energy system operates in the grid-connected mode, i.e., when the distributed energy system is parallel to a large power system through the VSI inverter. Therefore, the exact compensation of this nonlinearity in the VSI inverter over the entire range of output voltage is desirable. In this paper, the nonlinearity of VSI inverter output voltage and the harmonic distortion in the line current are analyzed based on an open-loop system and a L-R load. By minimizing the harmonic component of the current in a d-axis and q-axis synchronous rotating reference frame, the exact compensation factor was obtained. Simulations and experimental results in the low frequency and low output voltage region are presented.     

Output Impedance Design of Parallel-Connected UPS Inverters With Wireless Load-Sharing Control

This paper deals with the design of the output impedance of uninterruptible power system (UPS) inverters with parallel-connection capability. In order to avoid the need for any communication among modules, the power-sharing control loops are based on the$P/Q$droop method. Since in these systems the power-sharing accuracy is highly sensitive to the inverters output impedance, novel control loops to achieve both stable output impedance and proper power balance are proposed. In this sense, a novel wireless controller is designed by using three nested loops: 1) the inner loop is performed by using feedback linearization control techniques, providing a good quality output voltage waveform; 2) the intermediate loop enforces the output impedance of the inverter, achieving good harmonic power sharing while maintaining low output voltage total harmonic distortion; and 3) the outer loop calculates the output active and reactive powers and adjusts the output impedance value and the output voltage frequency during the load transients, obtaining excellent power sharing without deviations in either the frequency or the amplitude of the output voltage. Simulation and experimental results are reported from a parallel-connected UPS system sharing linear and nonlinear loads.     

Solid State Voltage and Frequency Controller for a Stand Alone Wind Power Generating System

This paper deals with the voltage and frequency controller of a wind turbine driven isolated asynchronous generator. The proposed voltage and frequency controller consists of an insulated gate bipolar junction transistor based voltage source converter along-with battery energy storage system at its dc link. The proposed controller is having bidirectional active and reactive powers flow capability by which it controls the system voltage and frequency with variation of consumer loads and the speed of the wind turbine. It is also having capability of harmonic elimination and load balancing. The proposed electro-mechanical system along with its controller is modeled and simulated in MATLAB using Simulink and power system block-set toolboxes. Performance of the proposed controller is presented to demonstrate voltage and frequency control of a wind turbine driven isolated asynchronous generator along with harmonic elimination and load balancing.     

基于智能整流技术的电网电流谐波补偿方法研究

目前用于电网电流谐波补偿的电器设备,主要以PWM整流器为主。基于PWM整流器的电源产品只能被动地减小自身向电网输出的谐波电流,而对电网中业已存在的电流谐波污染束手无策。为了解决电网中电流谐波污染以及相关联的电压波形失真问题,采用基于SRM(智能整流模块)技术对电网电流谐波进行补偿。仿真结果表明,基于SRM的电力电子装置在从电网吸取电流并在向负载供电的同时,还能对电网电压的波形进行补偿,使电网电压波形接近正弦波形。     

Pulse width modulation method of a single-phase multilevel inverter

A novel pulse-width modulation method for a multilevel single-phase inverter is proposed. The proposed method has the feature that the output voltage changes at each level, compared with the conventional method in which output voltage jumps from zero to the maximum level. Therefore, the adverse effects on load due to the high dv/dt are decreased. The method of determining pulse width is discussed, and the harmonic distortion factors and harmonic contents are analysed. Further improvement by increasing the number of pulses and the experimental results are also described.