Difference between grid connections of large-scale wind power and conventional synchronous generation

In China, regions with abundant wind energy resources are generally located at the end of power grids. The power grid architecture in these regions is typically not sufficiently strong, and the energy structure is relatively simple. Thus, connecting large-capacity wind power units complicates the peak load regulation and stable operation of the power grids in these regions. Most wind turbines use power electronic converter technology, which affects the safety and stability of the power grid differently compared with conventional synchronous generators. Furthermore, fluctuations in wind power cause fluctuations in the output of wind farms, making it difficult to create and implement suitable power generation plans for wind farms. The generation technology and grid connection scheme for wind power and conventional thermal power generation differ considerably. Moreover, the active and reactive power control abilities of wind turbines are weaker than those of thermal power units, necessitating additional equipment to control wind turbines. Hence, to address the aforementioned issues with large-scale wind power generation, this study analyzes the differences between the grid connection and collection strategies for wind power bases and thermal power plants. Based on this analysis, the differences in the power control modes of wind power and thermal power are further investigated. Finally, the stability of different control modes is analyzed through simulation. The findings can be beneficial for the planning and development of large-scale wind power generation farms.

Fundamental Research on Enhancing Operation Reliability for Large-Scale Interconnected Power Grids——An interview with Zhou Xiaoxin, chief scientist of "973 Program"

At the end of last year, the editors from Power and Electrical Engineers interviewed Zhou Xiaoxin on "Fundamental Research on Enhancing Operation Reliability for Large-Scale Interconnected Power Grids", a project of "973 Program". Mr. Zhou, the chief engineer of China Electric Power Research Institute(CEPRI) and an academician of Chinese Academy of Sciences, is the chief scientist in charge of this research project.

A novel decomposition and coordination algorithm for complex networks and its application to power grids

To analyze and control complex networks effectively, this paper puts forward a new kind of scheme, which takes control separately in each area and can achieve the network’s coordinated optimality. The proposed algorithm is made up of two parts: the first part decomposes the network into several independent areas based on community structure and decouples the information flow and control power among areas; the second part selects the center nodes from each area with the help of the control centrality index. As long as the status of center nodes is kept on a satisfactory level in each area, the whole system is under effective control. Finally, the algorithm is applied to power grids, and the simulations prove its effectiveness.

An In-Depth Study of Complex Power System Dynamic Behavior Characteristics for Chinese UHV Power Grid Security

In this paper,a series of major policy decisions used to improve the power grid reliability,reduce the risk and losses of major power outages,and realize the modernization of 21st century power grid are discussed. These decisions were adopted by American government and would also be helpful for the strategic development of Chinese power grid. It is proposed that China should take precaution,carry out security research on the overall dynamic behaviour characteristics of the UHV grid using the complexity theory,and finally provide safeguard for the Chinese UHV grid. It is also pointed out that,due to the lack of matured approaches to controll a cascading failure,the primary duty of a system operator is to work as a "watchdog" for the grid operation security,eliminate the cumulative effect and reduce the risk and losses of major cascading outages with the help of EMS and WAMS.

复杂大电网非预设性运行工况下的继电保护动作适应性仿真分析

非预设性运行工况下的突发事件多,导致继电保护逻辑的适应性较差,不合理区域较多,为此,进行复杂大电网非预设性运行工况下继电保护动作适应性仿真分析。分析历史常规故障,标记故障点最常发生位置,构建零序、负序方向元件模型、距离元件模型、纵联电流差动元件模型,观察复杂大电网非预设性运行工况下的电网参数变化情况,第一时间掌握电网的耦合性,不断选择电网所需的继电保护动作逻辑,确认继电保护动作适应性。仿真实验表明,将故障点设置在保护区域内和区域外,继电保护动作能够根据故障选择不同保护模型进行故障母线切除或者保护不动作,适应性好。

基于降维粒子群的大电网断面功率极限计算方法

随着电力系统的发展,系统运行方式日益复杂。为了提高电力系统运行安全水平,提出一种基于降维粒子群的大电网断面功率极限计算方法。首先综合考虑大电网静态安全稳定约束和暂态稳定约束,建立断面功率极限计算模型;然后,提出了基于功率灵敏度的降维粒子群算法,根据功率灵敏度和聚合系数对可调节发电机组进行分群处理,利用降维粒子群算法计算得到了极限功率、发电机组功率调节量以及极限功率制约因素,实现了大电网断面功率极限的快速寻优。最后在我国某地区2128节点电网和我国某跨区12643节点联网中验证了该方法的有效性和正确性。

保障各种复杂故障工况下解优质率的电网故障诊断解析模型

经典电网故障诊断解析模型是非线性0-1整数规划模型,其难以精确求解,启发式算法虽能获得可行解,但求解准确性和一致性难以保证,且求解时间较长,不利于基于诊断结果的故障排查和设备运维。对传统故障诊断模型进行改进,降低了模型的复杂度,实现了目标函数的线性化,据此构建了基于整数线性规划的电网故障诊断解析模型。Gurobi具有将启发式算法和整数线性规划求解算法有机结合的优点,将其应用于求解基于0-1整数线性规划的诊断模型,解决了传统启发式寻优算法因算法自身的局限性而陷入仅获得局部最优解甚至错解、以及求解速度慢等问题。通过算例对新型电网故障诊断模型的有效性和优越性进行验证,结果表明:相较于基于遗传算法、模拟退火算法、粒子群算法等启发式算法的传统模型,改进模型求解的速度与精度均显著得到了提高。

基于软件定义的新型电力系统分层自治电力平衡模式研究

新型电力系统是一个典型的复杂系统,源荷双侧的强不确定性导致电力电量时空分布极度不平衡,电力电量平衡逻辑发生了根本性变化,电力平衡面临巨大的挑战。为建立源网荷储多元协同互动的新型平衡模式,根据分层可以弱化复杂系统复杂性的理念,提出了基于能量自治单元的分层自治电力平衡模式。能量自治单元具备自调度、自平衡能力,在不同市场模式下具备不同的具体形态,将成为多元海量资源参与电力市场的有效途径。基于软件范型理论,指出能量自治单元应具备多元融合的架构模型、自适应运行机理和持续演化的生命周期,同时介绍了基于软件定义的能量自治单元软硬件解耦构建思路。最后,对能量自治单元构建的关键技术进行了讨论和展望。

Coordination of PSS and FACTS Damping Controllers to Improve Small Signal Stability of Large-scale Power Systems

This paper presents an approach for designing parameters of power system stabilizer(PSS)and FACTS damping controllers in a large scale practical power system.The objective is maximizing damping ratio of the target mode,and tracking technology(MTT)is used to avoid frequent alternations of target mode in optimization procedures.An improved planted growth simulation algorithm(IPGSA),which has high search efficiency and quick convergence speed,is proposed to optimize controller parameters coordinately.Based on case study of a large-scale power grid,and by using local and interregional low-frequency oscillation modes as target modes,simulation results verify proposed method in this paper.Furthermore,coordination optimization strategy adapted to multi-operating conditions demonstrates that the proposed approach is robust.

Cascading Failures in Power Grids: A Load Capacity Model with Node Centrality

Power grids,due to their lack of network redundancy and structural interdependence,are particularly vulnerable to cascading failures,a phenomenon where a few failed nodes—having their loads exceeding their capacities—can trigger a widespread collapse of all nodes.Here,we extend the cascading failure(Motter-Lai)model to a more realistic perspective,where each node’s load capacity is determined to be nonlinearly correlated with the node’s centrality.Our analysis encompasses a range of synthetic networks featuring small-world or scale-free properties,as well as real-world network configurations like the IEEE bus systems and the US power grid.We find that fine-tuning this nonlinear relationship can significantly enhance a network’s robustness against cascading failures when the network nodes are under attack.Additionally,the selection of initial nodes and the attack strategies also impact overall network robustness.Our findings offer valuable insights for improving the safety and resilience of power grids,bringing us closer to understanding cascading failures in a more realistic context.

基于改进蚁群算法的复杂电网继电保护自动整定方法

针对应用传统方法整定后动作延时较大的问题,提出基于改进蚁群算法的复杂电网继电保护自动整定方法。将复杂电网继电保护整定问题转化为非线性整数规划问题,构建一个以反时限过流保护动作时间最小为目标的自动整定模型,采用自适应思想改进蚁群算法后形成自适应最大最小蚁群算法,求解模型得到最佳整定方案。结果表明,应用设计方法后继电保护整定动作时间为0.464 s,电网可以快速恢复正常运行状态。

基于复数滤波器的电网电压同步技术

电网正序电压矢量角是可再生能源发电系统能够正常接入电网所需具备的最基本也是最重要的信息,锁相环是得到此信息的有效方式。该文首先分析锁相环的基本原理,然后分析锁相环的改进方式,根据分析结果提出两相静止坐标系下的改进复数滤波器的锁相环。通过仿真验证改进复数滤波器能够快速准确地分离出电网三相电压的正负序分量,并能够在一定程度上对电网电压的谐波进行衰减。

基于深度强化学习的电网关键节点识别

电网中某个关键节点发生故障,可能会引起级联失效,导致整个区域大面积停电。针对电网关键节点识别问题,提出了基于深度强化学习的电网关键节点识别模型。该模型通过图神经网络GCN对电网网络结构进行感知,对动作和状态进行向量表示,通过DQN的决策,选择最优动作,进行梯度回传,不断迭代优化参数,得到最优模型。基于该模型设计了电网关键节点检测算法KNDDRL,并在不同网络上进行了大量的实验,实验结果表明该算法能够有效识别电力网络中的关键节点,其效果优于所比较的代表性算法。

基于图像筛选的两阶段复杂作业人员行为动态风险辨识

电网作业涉及高压电力设备、带电设备以及复杂的作业场景,人员面临电击、触电、高温等危险,存在严重的人身安全风险。传统的人身风险感知方式受限于人工干预,存在感知能力不足、时效性差等问题。人工操作也容易受到主观判断和疲劳等因素的影响,导致风险漏判或误判。此外,目前的防控技术主要集中在单一维度上,依赖于人工监视,效率低、成本高,缺乏智能化、立体化、全方位的综合防控手段。针对上述问题,该文利用先进的感知技术、图像处理技术、人工智能等方法,提出基于图像筛选的两阶段复杂作业人员行为动态风险辨识方法,以实现对复杂作业环境中人身风险的准确感知、及时预警和立体化防控,可以为电网行业提供更可靠、高效的人身风险管理和防控手段,提升作业安全水平,降低人员伤亡事故的发生风险。

基于半监督机器学习的复杂电网连锁故障诊断方法

复杂电网连锁故障诊断性能过差会降低电力系统运行效率,为了及时监测复杂电网连锁故障,提升电力系统运行效率,提出基于半监督机器学习的复杂电网连锁故障诊断方法。根据电网负荷状态和电力信息物理系统建立复杂电网连锁故障模型,利用交叉小波和主元分析提取模型内故障特征。将故障特征与隶属于半监督机器学习的LCop K-means算法结合,根据算法输出的分类结果实现复杂电网连锁故障诊断。实验结果表明,所提方法诊断延迟较小,且故障区域的定位能力较强。

基于直流潮流的电力系统停电分布及自组织临界性分析

基于利用直流潮流模拟电力系统连锁故障的OPA模型,研究了电力系统线路可靠性、线路容量增加方式以及负荷波动对复杂电力系统停电分布的影响和电力系统的自组织临界性。结果表明:输电线路可靠性和小的负荷波动对停电分布影响不大,而大的负荷波动对停电分布影响很大,可能导致连锁故障的发生;加强传输线路的建设可以有效减少停电频率,进而降低系统的运行风险;此外,可从系统总负荷需求和网络总传输容量比值的角度初步揭示电力系统的自组织临界性。

特高压网架方案功能和可靠性分析

电网规划方案的合理性需要依据它的功能、经济性、可靠性、灵活性、适应性等多方面的综合协调程度来判断。为此,在梳理、分析和总结特高压网架方案性能研究已有成果的基础上,对特高压(UHV)网架的功能需求及不同网架方案在功能和可靠性方面的差异进行了补充分析,并进一步论述了中国发展特高压交直流电网的必要性、可行性和合理性;在系统可靠性方面,补充论述了不同网架方案的输供电能力充裕性;在系统安全的复杂性方面,补充论述了发生连锁故障的条件和电力系统大停电过程的复杂性。研究结果表明:若受端电网只能通过20回(7回送水电和13回送火电)特高压/超高压(UHV/EHV)直流输电线路大规模接受远方电力,则仅由水电季节性出力降低和部分直流停运便可直接导致该受端电网电力不足概率高达0.152;通过形成坚强网架后的特高压交直流输电网架方案来满足我国的输电需求相对比较可靠;电力系统安全防御体系的缺陷是造成电力系统特大规模停电的重要原因,因此在建立特高压交直流大电网的同时,应建立新一代电力系统安全监控系统,以完善大电网的安全防御体系。研究结果为特高压电网规划方案的多属性综合评价提供了参考。

利用社区挖掘的快速无功电压分区方法

针对电力系统无功网络具有强区域解耦性的特点,利用复杂网络理论中的社区网络挖掘方法,即发现复杂网络中的抱团特性,提出了一种电网无功快速分区方法。首先,分析了电力网络的物理特性与运行特性,结合复杂网络理论的相关参数定义,构建了符合电力网特点的拓扑模型;然后,利用社区网络挖掘法对无功拓扑进行了划分,并将结果与其他分区方法进行了对比分析。算例结果表明:兼顾了电网物理与运行特性的社区网络分析法与已有无功分区方法有着近似结果,有一定的合理性,且计算方法简单快速,符合复杂电网分析和工程计算需求。

考虑电力系统规划的OPA模型及自组织临界特性分析

为便于对电网连锁故障进行研究,介绍了与电网升级演化的触发息息相关的电力系统发展诊断指标,在此基础上提出一种改进OPA模型。该模型在慢动态环节加入电网规划的作用,模拟负荷变化、发电厂新建扩容、变电站新建扩容、输电线路新建改造等较长时间尺度上的电网演化升级过程;在快动态环节充分考虑调度、继电保护等在连锁故障过程中采取的措施及发挥的作用,模拟由于线路开断或短路、发电机退出运行等故障引发的连锁故障。利用所提模型对河南开封商丘地区220 kV及以上主干电网进行仿真测试,在长时间尺度上模拟电网演化升级的过程,同时统计不同升级触发阈值下的故障规模分布,从而求得系统临界状态所对应的触发阈值。仿真结果表明,文中所提的考虑电力系统规划的OPA模型能够较好地模拟电网生长演化,反映连锁故障产生和传播的过程,对未来的电网建设及大停电的整体预防有一定指导意义。

复杂网络的社团发现方法在电网分区识别中的应用研究

电网传统分区方案主要依据地理和行政区域,这样的分区往往对网络结构没有太多关注,而引发大停电事故又多源自分区联络线。复杂网络理论中的社团发现利用节点之间的连接关系来识别网络拓扑分区,与电网的分区结构极为相似。简介了社团结构及其模块化Q函数的概念及其评价指标,提出了基于社团发现的电网分区方法。利用电网潮流和阻抗参数作为边的权重建立四种不同的加权复杂网络模型,引入Louvain改进层次算法,并结合实际电网的特点对分区流程进行了实用化改进。基于标准的IEEE39、118、300节点电网及南方电网,分析了不同模型下的电网分区结果,论证了其有效性和准确性。