基于CAN总线的低压断路器新型可通信智能控制器研制

介绍了一种新型的基于CAN总线的低压断路器可通信智能控制器的研制与开发.对系统构成、硬件组成、实时多任务软件设计、上位机监控软件以及测量与保护算法等作了说明,并阐述了80C196KC和外围可编程器件PSD934F2及通信接口的设计.目前,该控制器样机已投入运行,同上位机联接构成分布式监控系统.经现场试验表明,该控制器能较好地实现测量、保护、监控与通信等功能,具有广阔的应用前景.     

中低压直流配电系统的分散式统一控制策略

中低压直流配电系统由中压直流母线、低压直流母线、直流变压器等组成,具有多电压等级、多直流母线、多变换器的特点,系统的运行方式与协调控制策略更加复杂。文中以中低压直流配电系统为研究对象,提出了一种基于直流母线电压信号的分散式统一控制策略。直流母线上的光伏发电单元、储能单元、燃料电池单元均采用分散式控制策略,根据直流母线电压调整各自的工作模式。直流变压器采用统一控制策略,集功率控制、中压与低压直流母线电压调节功能于一身,直流变压器根据中压与低压直流母线电压偏差的标幺值,自动调节传输功率的大小与方向,从而实现系统的全局功率均衡。最后,在MATLAB/Simulink中搭建了中低压直流配电系统的仿真模型,并对多种运行状态和场景进行了仿真分析,验证了所提控制策略的有效性。     

Nonlinear maximum power point tracking control and modal analysis of DFIG based wind turbine

The doubly fed induction generator based wind turbine (DFIG-WT) has strong nonlinearities originated from the aerodynamics of the wind turbine and the coupled dynamic of the DFIG, and can operate under a time-varying and wide operation region. This paper investigates a feedback linearisation controller based on the detailed model of the DFIG-WT, the control objective is to maximize energy conversion for this system. The original nonlinear system is partially linearized to a third-order linear system and a remained second-order internal nonlinear system. Fully decoupled control of the external dynamics is achieved, and the stability of the remained internal dynamics is analyzed via Lyapunov stability method. Moreover, modal analysis is applied for the nonlinear system controlled by the proposed nonlinear controller to verify its global optimal performance and low-voltage ride-through (LVRT) capability over various wind operation range. Simulation studies verify that more accurate tracking and better LVRT capability can be achieved in comparison with conventional vector control (VC).     

Modified predictive control for both normal and LVRT operations of a Quasi-Z-Source Matrix Converter based WECS

A new Wind Energy Conversion System (WECS), a Permanent-Magnet Synchronous Generator (PMSG) fed by a Quasi-Z-Source Matrix Converter (qZSMC), is proposed. At the same time, the paper proposes a Modified Predictive Control (MPC) for both normal and Low Voltage Ride-Through (LVRT) operations of the proposed WECS. First, the qZSMC comprised of a Three-Phase Quasi-Z-Source Network (TPQZSN) and a Matrix Converter (MC) is analyzed in both time and frequency domains. The TPQZSN is modeled using state–space averaging method and its transfer functions are derived. The transfer functions are then analyzed using Bode plot, and eventually a guide to select the proper passive components of the qZSMC is rendered. A MPC is proposed to control grid-side quantities while the generator speed is controlled by shoot-through adjustment. Unlike the Traditional Predictive Control (TPC), the proposed MPC can be applied to z-source converters, while considerably reducing output current ripples. The proposed control system is further adapted to enhance LVRT capability of the proposed WECS. The performance of the proposed WECS is evaluated under both normal and abnormal working conditions, comparing it with the Traditional MC-based PMSG-WECS (TMC-WECS).     

考虑撬棒保护接入的双馈感应发电机转子磁链动态特性

撬棒保护电路的接入会改变低电压穿越过程中双馈感应发电机(DFIG)定转子磁链间的耦合过程和耦合强度,由此将影响机组磁链衰减动态和撬棒保护性能。针对这一问题,提出了一种刻画定子磁链与转子绕组交链感应作用的磁链耦合系数,将电网故障后电机的磁链暂态耦合过程处理为不同状态的叠加,综合研究撬棒电阻对转子感应磁链正序、负序和暂态反向交流分量幅值和相角的耦合规律,用转子磁链空间矢量图和矢量轨迹图描述转子磁链动态响应过程。最后,针对电网不对称故障下撬棒取值的问题,提出了一种基于转子磁链幅值配比原理和最优倾角的撬棒阻值选取方法。该方法可减小磁链耦合不当对机组的暂态冲击,从而有效改善机组的无功外特性和瞬态性能。采用MATLAB/Simulink仿真验证了理论分析和所提方法的正确性。     

一种低压用户故障快速定位方法的分析与研究

提出了一种通过综合分析低压报修用户的户号、户名、电话号码及故障地址等报修信息,将低压用户报修信息与本地存储的低压用户基本电力信息(包括户名、户号、联系电话、地址)进行智能匹配,对低压报修用户进行快速精确定位,同时获取配电网故障信息的方法。在具备低压建模的情况下,通过低压拓扑分析获取低压报修用户所属表箱、所属变压器等相关配网设备的运行信息,实现低压报修用户故障的快速且准确定位,协助抢修调度员快速且准确进行抢修指挥,对提高电力抢修效率,缩短停电时间、减少经济损失、改善服务质量等方面都具有很重要的现实意义。     

低压电力线信道脉冲噪声的幅值与宽度特征

在低压电力线信道的各种噪声中,脉冲噪声可能会使通信系统引起瞬间误码率升高,严重影响了低压电力线通信可靠性。根据脉冲噪声的幅值和宽度与背景噪声的区别,即幅值相差10~50 d B,且脉冲宽度约为几十微秒到几毫秒的特性,在时域中,通过窗函数设定脉冲噪声门限值过滤低压电力线背景噪声,根据实测数据计算出信号噪声中的最大值和最小值,将信号变化范围划分为四组矩形窗函数,以识别出50~200 k Hz频率范围的脉冲噪声。     

基于低电压穿越控制策略的风电场等值方法

风电场通常包括多台同类型的风电机组,在大电网仿真计算中需要将风电场等值,以减小仿真规模并保证仿真的准确性。提出了基于风电机组低电压穿越特性的风电机组倍乘等值台数确定方法,该方法主要考虑了实际风电场中各风电机组出力不同对风电场等值的影响,基于双馈、全变流类型风电机组在低电压穿越期间的有功、无功控制策略,确定比较合理的等值机组台数,最后将风电场等值为多台出力相同的风电机组。通过对实际风电场的仿真分析表明,在不同控制方式下,综合考虑不同电压跌落水平的有功、无功最佳等值台数是一个范围,进而可以综合确定一个等值台数,以兼顾准确性和保守性。一般情况下,离线仿真可选择最小可能台数,在线仿真可选择有功最佳台数范围内的最小台数。     

低压配电系统电涌保护器能量配合研究

电涌保护器(SPD)的能量配合是低压配电系统防雷工程中的重要课题。基于理论计算和ATP-EMTP仿真,研究一端口限压型SPD在短波(8/20μs)和长波(10/350μs)下的能量配合问题,着重分析SPD级间距离和参数配合对这种配合的影响。提出金属氧化物压敏电阻(MOV)伏安特性研究的一种假设,给出了级间电缆的长度与后级SPD分流比的关系曲线。结果表明:短波情况下,10 m的级间电缆可将后级SPD电流限制在总电流的20%以内;长波情况下,80 m的级间电缆才能达到相近的效果。     

Multiobjective optimization in combinatorial wind farms system integration and resistive SFCL using analytical hierarchy process

This paper presents a positive approach for low voltage ride-through (LVRT) improvement of the permanent magnet synchronous generator (PMSG) based on a large wind power plant (WPP) of 50 MW. The proposed method utilizes the conventional current control strategy to provide a reactive power requirement and retain the active power production during and after the fault for the grid codes compliance. Besides that, a resistive superconducting fault current limiter (RSFCL) as an additional self-healing support is applied outside the WPP to further increase the rated active power of the installation, thereby enhance the dc-link voltage smoothness, as well as the LVRT capability of the 50 MW WPP. This is achieved by limiting the exceed fault current and diminishing the voltage dip level, leading to increase the voltage safety margin of the LVRT curve. Furthermore, the effect of the installed RSFCL on the extreme load reduction is effectively demonstrated. A large WPP has a complicated structure using several components, and the inclusion of RSFCL composes this layout more problematic for optimal performance of the system. Hence, the most-widely decision-making technique based on the analytic hierarchy process (AHP) is proposed for the optimal design of the combinatorial RSFCL and 50 MW WPP to compute the three-dimensional alignment in Pareto front at the end of the optimization run. The numerical simulations verify effectiveness of the proposed approach, using the Pareto optimality concept.