柔性直流输电应用于南方电网的研究

柔性直流输电技术具有可控性强、对环境影响小、适合中小容量电力远距离输送等优点。总结和分析目前国内外关于柔性直流输电技术应用与设备的相关信息,结合南方电网规划和能源结构发展趋势,研究柔性直流输电技术在南方电网应用的必要性、可行性及应用前景,并提出南方电网应用柔性直流输电技术的如下可能项目：大规模海上风电场接入系统;实现区域联网以便提高电网供电可靠性;应用于珠三角等大城市负荷密集地区供电;向远方孤立负荷供电。     

H桥级联型逆变器的积分复位控制方法研究

现有的阶梯波调制的级联逆变器的控制方法,由于计算耗时长,在级联单元数超过5个的H桥级联逆变器中难以应用。为解决这一问题,对其采用积分复位控制方法。该方法基于面积等效原理,通过输入输出积分值的比较来计算开关角。此方法计算简单、耗时短,故可用于H桥数更多的级联逆变器的控制。通过仿真验证了该方法的正确性和有效性。     

弱电网下基于锁相控制并网变换器小扰动同步稳定分析

该文对弱电网下基于锁相控制并网变换器的小扰动同步稳定问题进行研究。首先,以机理化揭示并网变换器同步特性为目标,通过将其和传统同步机的同步动态进行类比等效,建立适用于并网变换器同步稳定分析的类Heffron-Phillips动力学模型。进而借鉴传统电力系统低频振荡分析思路,采用复转矩系统法分析思想,将锁相环主导的同步振荡模式阻尼分为两部分:锁相环自身固有阻尼分量和弱电网下复杂控制耦合引入的附加阻尼分量,进而从阻尼特性的角度揭示弱电网下并网变换器同步稳定机理,并从影响固有或附加阻尼分量的角度,研究电网阻抗、控制器参数等因素对小扰动同步稳定性的影响。该文研究结果清晰揭示了弱电网下并网变换器同步失稳机理,并为后续同步稳定控制指明了思路。     

营配信息集成在遵义电网的建设分析

阐述了建设营配信息集成系统的目的，详细探讨了在营配信息集成系统建设过程中的三个关键问题，即整个营配信息集成系统的功能架构，数据流结构及系统的技术架构，最后对营配信息集成系统建设进行了总结。     

Grid integration improvement for single-phase inverters of small wind turbines under distorted voltage conditions

In this work, an enhanced control method for the grid-tied single-phase inverter in small wind turbines based on PMSG (permanent-magnet synchronous generator) under grid voltage distortion is introduced. Composite observers are designed for decomposing harmonic and fundamental components of the grid current and voltage accurately, which facilitate current control action and synchronize the inverter with the grid. Grid voltage phase angle is detected by an advanced PLL (phase-locked loop) scheme based on the grid voltage fundamental component. The inverter current is adjusted by multi-PR (proportional-resonant) controllers, where its harmonic components are regulated to zero resulting in a sinusoidal grid current. In this scheme, the DC-link voltage is maintained at constant by a DC boost converter, while generator output power is controlled by the grid-tied inverter. An MPPT (maximum power-point tracking) operation of wind turbine is obtained, with which generator speed is estimated from the input voltage and current of the DC boost converter, thus avoiding the use of an expensive and complex mechanical sensor. The presented method is proved through experimental investigation, where experimental results show that the THD (total harmonic distortion) of grid current is about 3% under 12.25% THD of the grid voltage.     

Efficiency enhancement scheme of cascaded multilevel grid-connected inverter and its improvement to eliminate effect of non-ideal grid conditions

In this paper, an online efficiency enhancement scheme of a cascaded multilevel grid-connected inverter for renewable energy generation systems is researched in detail. Taking the special grid current standard as the limitation condition, an efficiency enhancement scheme with adjusting carrier frequency in real time is proposed. Furthermore, the effect of the harmonics and DC offset of the tied grid on the enhanced phase locked loop (EPLL) is analyzed and a hybrid filter based EPLL is proposed to eliminate the former effect. With the improved EPLL, the amplitude, phase angle and frequency of grid are all estimated correctly and the performance of the efficiency enhancement scheme is maintained even under non-ideal grid conditions. Detailed experimental results validate the accuracy and practicability of the improved EPLL and efficiency enhancement scheme.     

海南电网联网后的频率稳定与措施

海南电网与南方电网主网联网后,基本解决了海南电网存在多年的“大机小网”问题,但也可能面临新的频率稳定问题。对联络线送受电情况下发生故障时对海南电网的影响进行了分析,对联网后海南电网的低频减载和高周切机方案、联络线的稳控措施、联络线的功率控制和海南电网机组的带负荷方案等提出了相应措施。建议联网后应控制联络线功率,并在事故情况下采取迅速的调控措施;孤网情况下应按带负荷方案限制大机组出力;建议在联络线上装设两套安稳装置;建议海南联网后适当调整现有低频减载方案,保留目前的高频切机方案。     

南方电网一次调频现状研究

介绍南方电网一次调频的现状,包括投运容量、技术参数等,通过分析近三年频率合格率的提高,以及两次机组跳闸后频率变化对比,说明了一次调频投入后的良好效果。同时,指出目前存在的问题,并从专业管理、控制策略、分析手段上提出一系列措施以提高南方电网一次调频水平。     

2MVA无串联变压器级联多电平动态电压调节器的设计与仿真

研究了基于级联多电平结构的无串联注入变压器的2MVA动态电压调节器(Dynamicvoltagerestorer,DVR)的系统设计方案,针对DVR的主电路拓扑、电压暂降检测算法、底层载波移相控制策略、储能计算、滤波器设计及逆变器部分的损耗进行了分析研究,并对某生产基地6kV系统的电压暂降问题完成了DVR装置主电路参数和控制电路的功能设计,采用仿真软件EMTDC/PSCAD进行了仿真研究,验证了文中所提设计方案的正确性及有效性。     

不对称电网电压下MMC-HVDC系统功率波动抑制策略研究

电网电压不对称时,在基于模块化多电平换流器的高压直流输电(Modular Multilevel Converter based High Voltage Direct Current,MMC-HVDC)系统中,针对MMC交流侧输出产生的有功功率和无功功率二倍频波动问题,提出了将电网电压、电流均变换至正序dq坐标系下进行电流参考值计算的控制策略,可同时抑制MMC交流侧输出的有功功率和无功功率的二倍频波动。此外,电网电压不对称时,在正序dq坐标系下,电压d、q轴分量中除直流分量外,还将含有由负序分量引起的二倍频分量。若在锁相环的设计中不考虑此二倍频分量,则电网电压不对称时系统整体控制性能将会受到影响。据此设计了基于二倍频陷波器的频率自适应锁相环,在电网电压不对称情况下可准确锁定正序电压相位,并计算电网正序电压幅值及负序电压在正序d、q轴上的分量值,用于所提控制方法中的dq变换及功率波动抑制环节中电流参考值的计算。最后通过仿真验证了所提方法的可行性和有效性。     

Short term generation scheduling of cascaded hydro electric system using novel self adaptive inertia weight PSO

Hydro power plants are multipurpose projects, which are not only generating power but also responsible for the fulfillment of irrigation requirements of nearby zone. To harness the potential energy of released water Canal Head Power Houses (CHPHs) are also located at irrigation canals of the multipurpose projects. The present paper proposed a Novel Self Adaptive Inertia Weight Particle Swarm Optimization (NSAIW_PSO) approach to determine the optimal generation schedule of real operated cascaded hydroelectric system located at Narmada river in Madhya Pradesh, India. Here generation scheduling problem has been formulated in two cases. Case one considers natural inflows, evaporation losses and irrigation requirements assuming no generation through CHPHs. Whereas second case considers all above factors along with generation through CHPHs. Results show that in case two the amount of water discharge through all hydro power plants is less in comparison to case one to fulfill the same load demand, which shows the importance of CHPHs.     

十一电平链式STATCOM直流电容电压平衡控制研究

直流侧电容电压的不平衡及其控制是链式STATCOM要解决的关键问题。笔者给出了链式STATCOM直流电容稳态数学模型,分析了逆变桥参数对电容电压不平衡的影响,指出开关脉冲延时不同、混合型损耗差异以及并联型损耗差异是造成电容电压不平衡的主要原因。结合十一电平STATCOM,提出采用基频开关法投和基频脉冲循环换位法可以有效的保持链式STATCOM直流电容电压的平衡稳定,STATCOM的PSCAD模型及其仿真验证了该方法的可行性和有效性。     

海南电网与主网联网后的稳控措施研究

研究海南电网与南方主网联网后,联络线故障和联络线延伸断面故障的稳控措施,对海南电网原有稳控措施适应性进行了分析,指出对于安稳装置而言,联网后反而复杂了,因为它既要适应联网方式,叉要适应孤网方式。因此,安稳系统的软硬件均需做一定的升级改造。文章给出了2009年海南电网稳控系统的改造方案。     

单片开关集成电路的分析与应用

单片开关集成电路TOP223,集成了功率开关管和PWM控制器及其它一些逻辑控制电路,是一种典型的高压功率集成电路.本文分析美国功率集成电路公司TOPSWITCH-Ⅱ系列中TOP223的内部结构,介绍该芯片的功能特点、工作原理,并通过CADENCE软件对该芯片的部分内部结构进行了设计与仿真,并给出仿真分析结果.文章还给出该芯片的一种应用电路.     

基于广州抽水蓄能厂机组全停的电网调度运行策略分析

广州抽水蓄能厂机组全停将极大威胁电网的安全稳定运行,同时也给调度实时运行带来很大困难。就此,分析了在广州蓄能厂机组全停下的广东电网调度运行策略,提出相应的调峰调频策略,对电网调度实际运行有一定指导意义。     

电网极低频电磁场预防的国际经验及启示

电网企业中存在的极低频电磁场对职业人员的潜在健康影响具有不确定性。针对极低频电磁场的职业接触限值,世界卫生组织推荐以国际非电离辐射防护委员会导则及美国电气电子工程师协会标准为依据。在梳理国际权威机构及西方国家关于极低频电磁场职业接触限值研究的基础上,参考国际权威机构的建议,针对我国电磁场管理现状,提出电网极低频电磁场预防策略与建议。     

Power quality enhancement using fuzzy sliding mode based pulse width modulation control strategy for unified power quality conditioner

This paper proposes a fixed switching methodology based on fuzzy sliding mode pulse width modulation (FSMPWM) control strategy for three-phase three-wire unified power quality conditioner (UPQC). The proposed FSMPWM control technique eliminates numerous power quality (PQ) problems such as current harmonics, load unbalance, voltage sag/swell, voltage unbalance, voltage distortion and phase-angle jump existing in the power distribution network. Initially, the design of FSMPWM is based on the implementation of sliding surface by proper extraction of reference current and voltage signals for UPQC. Subsequently, the equivalent control law is formulated for both shunt and series converter. With this consideration, Mamdani fuzzy rule base is designed at the sliding surface for generation of switching pulse. Moreover, the proposed method eliminates the chattering effects by smoothing the control law in a narrow boundary layer for generating fixed switching pulse for both shunt and series converter. The performance of proposed UPQC system has been simulated and analyzed by MATLAB/SIMULINK followed by real-time experimental studies accomplished with a real-time-hardware-in the loop (HIL) system in OPAL-RT simulator. Additionally, the efficacy of this proposed technique is compared with a conventional sliding mode controller (CSMC).     

南方电网发电机组一次调频性能评价方法分析与改进

目前南方电网发电机组一次调频性能评价方法有2种:基于PMU数据的评价方法(以下简称为方法A)和基于一次调频动作电量的评价方法(以下简称为方法B)。本文结合南方电网大负荷扰动后系统频率变化特性,以及南方电网2010年1-6月份各类型机组一次调频性能评价数据,分析了两种方法的实际应用情况:方法A在评价调频性能时出现了一定偏差;方法B中水、火电机组的一次调频参数设置存在差异,不利于掌握水电机组的一次调频性能。就此,建议在方法A中引入一次调频性能指数B,以及在方法B中调整水电机组一次调频性能评价的启动条件,以适应目前南方电网的频率特性。     

基于FNET实测数据分析川渝电网频率动态特性

电力系统频率动态监测网(FNET)在川渝电网实现了对频率的同步测量。基于FNET实测频率数据,评价了近几年川渝电网频率质量;呈现了川渝电网频率的时空分布特性;采用统计学方法研究了扰动后川渝电网的频率恢复能力;利用TLS-ESPRIT辨识方法提取川渝电网低频振荡信息,观测到0.25 Hz模式下成都和攀枝花之间的弱阻尼低频振荡现象。相关结论有助于认识川渝电网频率质量和动态特性,完善川渝电网稳定控制方案。     

基于WAMS的南方电网低频振荡调度应对策略

南方电网区域间弱阻尼振荡已得到有效控制,但局部的以及机组原因引发的低频振荡问题仍然突出。探讨了调度运行中应对低频振荡的策略,从振荡前的预警预防和振荡发生后的紧急控制两个方面提出针对性应对措施。采用基于类噪声信号的模态参数辨识方法进行振荡前的预警预防,可摆脱对模型和参数的依赖,利用大量冗余数据提高结果可信度,在线监视区间模式和局部模式的阻尼比,实现对危险模式的预警预防。采用基于振荡能量的振荡源定位方法进行振荡事故紧急处置,可以在振荡发生后快速准确的找到振荡的起因,定位振荡源,指导调度员采取针对性的措施快速平息振荡。利用实际振荡事故说明了所提调度应对策略的流程,并验证了所提方法的有效性。