Resilient Fixed-Order Distributed Dynamic Output Feedback Load Frequency Control Design for Interconnected Multi-Area Power Systems

The paper proposes a novel H∞ load frequency control(LFC) design method for multi-area power systems based on an integral-based non-fragile distributed fixed-order dynamic output feedback(DOF) tracking-regulator control scheme. To this end, we consider a nonlinear interconnected model for multiarea power systems which also include uncertainties and timevarying communication delays. The design procedure is formulated using semi-definite programming and linear matrix inequality(LMI) method. The solution of the proposed LMIs returns necessary parameters for the tracking controllers such that the impact of model uncertainty and load disturbances are minimized. The proposed controllers are capable of receiving all or part of subsystems information, whereas the outputs of each controller are local. These controllers are designed such that the resilient stability of the overall closed-loop system is guaranteed. Simulation results are provided to verify the effectiveness of the proposed scheme. Simulation results quantify that the distributed(and decentralized) controlled system behaves well in presence of large parameter perturbations and random disturbances on the power system.

Study Hybrid Compensation Cophase Traction Power Supply System Schemes for High-Speed and Heavy Haul Electrical Railway with V Connection Transformer

In order to solve negative phase sequence problem of V connection transformer in the high speed and heavy haul electrical railway of China, the hybrid compensative co-phase traction power supply system which based on passive and active compensation is proposed. Firstly, There construction and capacity distribution are analyzed, and the compensation current of active equipment is gave;Second, the feature of the hybrid compensative schemes are discussed. In the end, the related simulation results have confirmed the effectiveness of the compensation schemes in this paper.

Study on the Application of UHVDC Hierarchical Connection Mode to Multi-infeed HVDC System

随着我国特高压交直流技术的广泛应用，多馈入直流集中落入受端负荷中心将是未来我国电网发展所面临的重要问题。为从电网结构上有效解决多馈入直流系统的问题，提出一种特高压直流分层接入交流电网的方式。研究分层接入方式直流多馈入短路比计算方法的适用性，从理论上对比特高压直流不同接入方式下多馈入直流电网的系统特性，证明特高压直流分层接入方式有助于提高多馈入直流系统的电压支撑能力，引导潮流在1000kV与500kV层级间合理分布。结合国家电网规划，仿真验证了特高压直流分层接入方式的优势。

Model and Algorithm for the Optimal Controlled Partitioning of Power Systems

解列是电力系统在故障时结构完整性得不到保证的情况下分裂为2个或多个孤立稳定运行子系统的过程或操作。及时恰当的主动解列操作将能有效地避免因保护连锁动作使得电力系统被动解列而崩溃所造成的巨额经济损失。结合图论中的相关概念和输电网最优解列的物理过程，建立电力系统最优主动解列断面选择问题的完整数学模型，并基于含连通图约束的背包问题（connected graph constrained knapsack problem，CGKP）及其求解算法提出“搜索＋调整”的2阶段求解方法。为降低问题的复杂性，将完整数学模型分解成图的最优平衡分割问题和基于优化潮流的调节问题，并分2个阶段分别求解。其中，图的最优平衡分割问题又被分解成多个CGKP，利用基于含CGKP的图分割方法进行求解。所提出的主动解列策略具有较强理论基础，计算复杂度低，算例的计算结果证明了该模型及算法的正确性和有效性。

Forecast of Power Generation for Grid-Connected Photo-voltaic System Based on Grey Theory and Verification Model

Being photovoltaic power generation affected by radiation strength, wind speed, clouds cover and environment temperature, the generating in each moment is fluctuating. The operational characteristics of grid-connected PV systems are coincided with gray theory application conditions. A gray theory model has been applied in short-term forecast of grid-connected photovoltaic system. The verification model of the probability of small error will help to check the accuracy of the gray forecast results. The calculated result shows that the ?model accuracy has been greatly enhanced.

A composite controller for grid connected photovoltaic systems

This paper addresses a new composite controller for a boost-buck inverter to interface the photovoha-ic array with the power grid.Based on dynamically tracking the maximum power point,two novel controlmethodologies are proposed to control the DC-bus and the output current for the inverter.First,a newlinear cycle discrete control algorithm is introduced to realize linear control of the DC-bus voltage and syn-chronously get the reference current for the inner current loop with a little calculation.Then,to assure agood adaptability to noise and model uncertainty,an auto-disturbance rejection controller is chosen as theoutput current controller,which does not depend on precise mathematics model.Thus,output current ofPV system to the grid is with low harmonic distortion and unity power factor.Simulations and experimentsare performed,and the results show that the system is of excellent robustness and effective.

Norton equivalent circuit for current control loop of grid-connected system

Modeling method for the current control loop of a grid-connected PWM inverter with the LCL output filter was discussed.Firstly,the current control loop with the LCL inverter-side current as feedback was established.Then,parameters of PI controller were calculated on the basis of an equivalent controlled object.Finally,Norton equivalent circuit for the current control loop of grid-connected system was derived by integrating one control equation,which connected the PWM inverter output voltage and the LCL inverter-side current,with two circuit equations,separately using the LCL inverter-side current and the injected current as loop currents.With the induced Norton equivalent circuit,system-level resonant and unstable issues on real grid-connected system applied in weak distributed power systems can be easily analyzed.The validity of substituting Norton equivalent circuit for grid-connected system is verified by simulation and experiment.

光伏多功能并网逆变器不同出力状态下无功和谐波优化方法

利用光伏多功能并网逆变器所具有的电能质量治理、谐波谐振抑制的主动优势,结合逆变器在不同出力状态下光伏发电系统的输出特性,构建光伏多功能并网逆变器不同出力状态下的无功和谐波优化方法。在所提3层优化策略中,上层优化策略以光伏并网有功功率最大化为目标函数,中层优化策略以电压谐波总畸变率和电压偏差达到相应电能质量规定指标为目标函数,下层优化策略以电压谐波总畸变率和电压偏差最小为目标函数,并采用自适应蚁群算法进行求解。基于IEEE 33节点系统进行算例分析,结果表明:基于逆变器不同出力状态的优化方法可以有效改善电网的电能质量,较好地提升电网运行的经济性;在系统稳定运行的基础上,光伏多功能并网逆变器在不同出力状态下分阶段、分主次地治理谐波和调整电压偏差,治理效果更佳。

基于直流电流瞬时微分的特高压直流分层接入系统非故障层换相失败预防控制策略

在特高压直流分层接入系统中,由于层间耦合作用,某一层交流系统发生故障可能导致非故障层换流器发生换相失败。为此,考虑到故障过程直流电流的变化,提出一种基于直流电流瞬时微分的换相失败预防控制策略。该策略基于故障后直流电流的变化特性,得到换相电流时间面积控制中触发角修正量,代替原有换相失败预防控制,提高非故障层换相失败预防控制的启动精度;同时基于电流预测量和等效直流输入电阻动态调整低压限流控制器的指令值,提高其响应速度。在PSCAD/EMTDC中搭建仿真模型对不同工况下所提控制策略进行验证。结果表明,该策略可降低高低端换流器同时发生换相失败的风险,改善故障后系统的运行性能。

考虑车网互动的园区电网动态双层能量管理策略

为解决大量接入的清洁能源出力波动和充电场内汽车数量的随机变化给电网能量管理带来的困难,提出一种园区电网双层优化控制策略.上层基于模型预测控制技术建立风光储集成动态优化模型,综合应用园区电池储能系统和电动汽车(EV)电池储能系统参与电网能量平衡.下层则考虑同时满足EV车主对EV的充电需求和上层能量调度的车网互动管理需求,制定园区电网内停车场的EV有序充放电策略.仿真算例验证表明:所提策略能将分散园区各处的EV储能集成为统一虚拟储能,扩展园区电网储能系统,增加可再生分布式电源的消纳与园区电网的经济效益.

构网型变流器:物理本质与特征

全球能源产业变革促进了电力系统电力电子化转型,以新能源为主体的电力电子化电力系统中同步机占比低,系统呈现低惯量、弱阻尼特征,引发了一系列运行问题。构网型变流器本质为电压源,能够主动构建电压频率,为系统提供惯量支撑,有利于改善系统稳定性,是提高新能源主动支撑能力的有效手段,近年来成为研究热点。该文从电力电子化电力系统的运行问题出发,梳理了下垂控制、虚拟同步机控制等典型构网型控制策略的实现原理及内在联系,建立构网型控制策略的统一数学模型;通过类比稳态条件下同步机与构网型变流器的电压频率构建原理,揭示了构网型变流器的物理本质,从电压频率构建、惯量阻尼支撑、同步机制等角度解释了构网型变流器的内涵与特性,可为构网型变流器的稳定与控制提供理论参考。

新型电力系统下分布式光伏规模化并网运行关键技术探讨

推进分布式光伏规模化并网是实现“碳达峰·碳中和”目标和构建新型电力系统的重要举措。基于此背景探讨面向新型电力系统的分布式光伏规模化并网运行关键技术。首先,归纳并阐述分布式光伏发展现状、并网方式及运行模式,分析大规模分布式光伏接入给电网调度运行带来的挑战。其次,面对上述挑战,从信息集成、监测预测、平衡调度、聚合控制等视角提出系统调度运行关键技术,助力电网调控模式转型升级。然后,考虑实际工程需求,构思满足电网安全稳定运行的分布式光伏技术标准体系,以期促使分布式光伏“可观可测、可调可控、友好互动”。最后,调研并梳理国外分布式光伏规模化并网运行先进经验,并对我国分布式光伏并网协同探索、运行服务支持及市场交易参与等课题提出建议。

光伏并网稳定控制系统设计方法及其在南方电网的应用与实践

随着新型电力系统的建设,电网的“双高”将显著影响电力系统的运行与稳定特性。因此提出了一种光伏并网稳控系统的标准化设计方案,包括组网通信架构、软硬件功能配置、出口方式设计和协调配合方法等,解决了目前光伏稳控出口仅能在“全站整切”或“全站整调”中人为二选一的局限性。该方案已成功应用于南方电网首个水光互补项目,RTDS仿真试验结果表明,所设计的稳控系统实现了功率快速精细化调节,通信延时短,通信组网可靠性高,能够适应实际电网的各种稳定性需求。

基于自启动系统的海上风电并网技术

针对目前海上风电项目建设存在并网周期长的问题,提出了一种自启动的风机并网方法,并基于该方法开发了一套风机并网调试自启动装置。该装置可以安装在海上升压站平台上,在大电网电源送达海上升压站前,通过海缆为风机提供稳定电源,在此期间提前完成风机各项调试与并网工作。待正式电源送达海上升压站后,风机直接并网,大幅缩短海上风电项目建设工期,帮助风机提前并网发电,创造可观的经济价值,并能够加速清洁能源并网,助力“碳达峰,碳中和”的能源环境战略目标实现。目前,该技术已在江苏如东多个海上风电场落地应用,现场试验数据验证了研制系统和所提方法的先进性与有效性。

弱电网下光伏并网逆变器谐振抑制方法综述

“双碳”目标背景下电力系统形成“高比例可再生能源”和“高比例电力电子设备”的“双高”趋势,以致电网呈现弱电网特性。弱电网下电网阻抗实时变化,导致光伏并网逆变器谐振频率偏移、逆变器集群多谐振峰等稳定性问题。针对光伏并网逆变器在弱电网下最新的谐振抑制方法尚未得到系统地归纳总结,从弱电网下逆变器单元谐振抑制方法和逆变器集群谐振抑制方法两方面综述“双高”电力系统下光伏并网逆变器谐振抑制热点控制方法,为光伏并网逆变器的稳定性提升指明发展方向。

基于EKS的风电并网系统频率特征参数辨识算法

新型电力系统建设背景下系统对接入风电的频率调节能力提出了要求。但风电在可调容量耗尽时将退出调频,导致系统等效惯量等参数和频率响应特性变化,影响系统切机切负荷等频率控制措施的正确动作。为此,提出一种基于扩展卡尔曼平滑算法(Extented Kalman Smoother, EKS)的风电并网系统频率特征参数辨识方法,可实现不同工况下系统频率特征参数的高效准确辨识。首先分析了风电场频率控制方法,建立了基于共模分量的风电并网系统频率响应模型,然后分析了EKS算法,进而提出了基于EKS的系统频率特征参数辨识方法,最后通过仿真算例进行了验证。仿真结果表明,所提方法可有效辨识不同工况下系统的惯量、阻尼等频率特征参数。

海洋核动力平台定位系统多体动力学模型试验验证

为验证海洋核动力平台定位系统多体动力学模型的合理性,从而提高该平台长期系泊的可靠性,本文采用多体动力学方法与缩比模型试验方法,对核动力平台定位系统进行建模与验证。基于定位系统多铰连接的拓扑结构,结合多刚体动力学理论,建立了定位系统的多体动力学仿真模型。搭建了定位系统1∶9缩比模型试验平台,并选取2种典型工况进行验证。研究结果表明:定位系统多体动力学模型计算的系泊腿受力与实验结果符合良好,平均误差在2%以内。算例分析发现,系泊腿受力循环次数主要集中在低幅值高均值区域。本文模型试验验证了所提出的定位系统多体动力学模型的可行性与正确性,能够为定位系统系泊能力的评估提供参考和借鉴。