关于抽水蓄能电站水库优化调度的研究

针对某抽水蓄能电站水库运行的特点，在满足电力系统调度要求的前提下，以整个调度周期内总发电收益现值最大为目标建立了优化调度模型。通过径流描述以及应用动态规划法进行优化计算，求解抽水蓄能电站水库优化调度方案。在求解寻优的过程中，既兼顾了面临时段和余留时期的效益，又考虑上水库的天然来水和下水库的区间来水，通过分析表明，所提模型与计算方法是可行和实用的。     

发电机内部冷却气流状态对定子温度场的影响

由于大型同步发电机运行状况以及结构的复杂性，定子径向通风沟内冷却流体的流动状态对定子温度场的分布有显著的影响。根据流体力学理论，推导了定子径向通风沟内二维流体运动的微分方程，给出了求解域和相应的边界条件及假设条件，采用有限体积法对流体场进行了计算，并且对冷却气体以不同的入射角度入射时径向通风沟内流场流速的分布进行了比较；建立了定子三维温度场的数学模型和物理模型，给出了求解域的边界条件以及各部分的损耗，针对上述流体场分布的不同情况，采用有限元法对定子三维温度场进行了数值计算；将计算结果与实测值进行了比较，得出了一些有益的结论。     

中型高压电动机暂态温度场分析及短时过载运行研究

针对中型高压感应电动机暂态温升难以准确计算的问题，以一台紧凑型中型高压感应电动机为例，采用电机内各物理场间强耦合与弱耦合相结合的多物理场三维动态耦合分析方法，对其暂态温升进行计算。根据电机内定、转子区域流-固耦合的特点，建立电机温度场与流体场的三维强耦合分析模型。利用电机动态数学模型、磁网络模型、集肤效应模型及流体网络模型对电机损耗、转速及入口流量等进行计算，并作为耦合边界条件实现与流-固耦合模型的瞬态弱耦合求解。模拟了电机起动过程中温度的变化过程，验证了研究方法的正确性。对短时工况不同负载条件下电机的温升进行计算，获取负载条件对电机温升的影响规律，为电机的短时过载运行提供依据。研究内容为中型高压电动机暂态温升的计算及保障电机多工况的安全运行提供了参考。     

基于JPCG算法的真空灭弧室三维电场有限元计算

建立了高压真空灭弧室三维电场有限元计算的模型及物理方程，分析了适用于大型稀疏矩阵求解的雅可比共轭梯度算法JPCG，给出JPCG算法的迭代流程。采用有限元法对高压真空灭弧室的三维电场分布进行了计算，同时应用JPCG算法来求解所得到的大型有限元方程组。最后采用不同的算法对真空灭弧室的自电容进行了对比计算，计算结果表明，采用JPCG算法可以明显减少有限元方程组求解的迭代次数，加快收敛速度，特别适合应用于三维电磁场有限元分析形成的大型稀疏方程组的求解，是用来计算大型有限元方程组的一种非常有效的方法。同时，真空灭弧室的自电容计算可以给真空灭弧室的优化设计提供参考。     

基于三维实景模型的水库无线视频监控系统

以前坪水库为例，水库建设期视频监控系统信号采用无线网桥传输，基于无人机航摄生成三维实景模型进行视频监控点及无线网桥布置设计。介绍了采用大疆无人机DJ1 PHANTOM4 PRO进行航飞倾斜摄影，采用Context Capture 3D生成三维实景模型的过程步骤，对基于三维实景模型优化监控点布设及视野和信道复核的方法进行了研究。实践表明，基于无人机三维实景模型的水库无线视频监控系统设计可靠，可为其他类似工程参考借鉴。     

基于混合法的油浸式变压器二维瞬态温度场仿真

温升是影响油浸式变压器正常运行的重要因素,为了得到变压器的温度场分布,提出一种基于混合方法的多物理场计算方法。对于油浸式变压器流体场和温度场的强耦合问题,混合方法考虑了温度对媒质物性参数的影响,采用迎风有限体积法和迎风有限元法依次计算流体场和温度场,即流体场和温度场依次循环求解,最终得到油浸式变压器启动过程瞬态温度场和稳态温度场。为了验证文中算法的有效性,采用换流变压器二维简化模型,分别采用文中方法和多物理场仿真软件Comsol计算了常温下的稳态温度场,计算结果验证了混合方法的准确性和有效性。在验证文中算法有效性的基础上,利用该方法分析了换流变压器常温环境下启动过程的瞬态温度场分布,分析结果可为工程提供参考。     

水库水温数学模型及其应用

对标准k-ε紊流模型进行浮力修正,建立了剖面二维及三维水库水温计算的浮力流模型并采用已建漫湾水库库区实测水温资料对模型进行了检验。将检验后的模型应用于瓯江滩坑水库的水温分布预测研究中,其中采用剖面二维模型进行全库水温分布预测,并为坝前三维模型提供进口边界;采用三维模型对近坝段水流结构以及水电站下泄水温进行精确模拟,从而实现下泄水温的精确模拟。根据计算结果,分析了水库建成后下泄水温与天然水温的差异,对比了各典型年不同电站开机组数和不同电站取水口高程条件下水库下泄水温的差别,为该电站取水口高程和机组运行方式的制定提供了一定的参考依据。     

大型变压器三维瞬态涡流场场路耦合模型

为分析变压器在端口电压约束下的电磁过程 ,本文研究了三维电磁场的场路耦合问题。根据A法和T法的各自特点 ,考虑变压器绕组的结构特点 ,引入外施电压的耦合 ,分别建立基于A法和基于T法的变压器三维场路耦合模型。将两种方法用于变压器绕组突发短路过程的计算 ,计算结果一致 ,但采用基于T法的三维场路耦合模型计算量小 ,非常适于涡流区所占比例较小的电磁设备的求解     

电力市场环境下多年调节水库年末消落水位研究

针对梯级水库中多年调节水库年末消落水位优选问题,结合电力市场环境下梯级水库中长期发电优化调度的特点,本文建立了电力市场环境下多年调节水库年末消落水位优选模型,并应用协同差分演化算法对模型进行了求解。通过乌江梯级水库实例验证,计算结果表明本文所提出的模型与求解方法具有可靠性与合理性,为电力市场环境下梯级水库发电优化调度提供了理论计算依据,具有应用推广价值。     

黄河上游梯级电站补偿效益研究

在分析补偿调节原则和方法的基础上，利用大系统理论研究黄河梯级水电站群电量补偿效益问题。根据黄河上游水库电站的特点，提出有效的计算方法－三层次计算法，每一层次建立了水库调节的数学模型，并采用模拟，模拟优化算法对其求解；模型计算结果表明，通过梯级补偿调节可以获得巨大的电量补偿效益。     

Transmission line individual phase impedance and related pilot protection

This paper proposes a kind of new Individual Phase Impedance (IPI) and a novel pilot protection scheme for transmission line based on the IPI. The IPI is calculated by the ratio of the voltage difference of fault-superimposed component to the current difference of fault-superimposed component at both terminals of the protected line. The IPI has accurate mathematical expressions and reasonable physical definitions for various line models. The calculated result of IPI can be used to distinguish the internal faults from the external faults. When the IPI is identical to the value of line positive-sequence impedance, the external fault is detected; otherwise, the internal fault is detected if it differs from that value. The feature of the pilot protection scheme is that the inter-phase coupling relation and the distributed capacitance based on the three-phase line model are directly considered and included in the IPI expression. The novel pilot protection can be used for long distance HV transmission lines with some preeminent performances which are deficiency in the conventional directional comparison pilot protection and current differential protection. The test results obtained by EMTP simulation and from a laboratory model of a simplified real power system have demonstrated that the pilot protection is of high reliability and good adaptability.     

Two-level optimal output feedback stabilizer design

Design of two-level system stabilizers is considered using an optimal reduced-order model whose state variables are torque angles and speeds. The reduced-order model retains their physical meaning and is used to design a two-level linear feedback controller that takes into account the realities and constraints of the electrical power systems. The two-level control strategy is used, and a global control signal is generated from the output variables to minimize the effect of interaction. The effectiveness of this controller is evaluated, and an example, the multimachine system, is given to illustrate the advantages of the proposed method. The responses of the system with the two-level scheme and optimal reduced order scheme are included for comparative analyses     

基于NI-PXI的分布式发电数模混合仿真系统

分布式发电(Distributed Generation,简称DG)技术是解决未来能源和环境问题的一个重要方向。这里提出一种分布式发电数模混合仿真系统的设计方案,用于分布式电源(Distributed Energy Resources,简称DERs)并网相关技术的研究。该方案采用NI-PXI为实时数字仿真平台完成分布式电源数字模型部分的实时计算,通过基于双PWM换流器的可控功率源模拟分布式电源的功率输出,作为混合仿真接口实现数字部分和物理部分之间信息交互,从而实现数/模混合实时仿真的目的。此处以双馈风力发电系统为例,验证了该方案的可行性,为研究分布式发电并网运行控制提供了良好、通用且便捷的实验平台。     

TWO-LEVEL OPTIMAL PI CONTROLLER DESIGN

ABSTRACT

This paper addresses the design of two-level Power System Stabilizers using an optimal reduced order model whose state variables are torque angles and speeds. The reduced-order model retains their physical meaning and is used to design a two-level linear feedback controller that takes into account the realities and constraints of eletric power system. The two-level control strategy is used and a global control signal is generated from the output variables to minimize the effect of interactions. Effectiveness of this controller is evaluated and an example of a multimachine system, is given to illustrate the advantage of the proposed method. Reponses of the system with two-level scheme and optimal reduced order scheme are included for comparative analysis.     

基于数字孪生模型电流动态时间规整差异度的变压器早期故障辨识

现有的早期故障辨识方法对于程度较为轻微的故障灵敏度低,且辨识方法多为离线检测。结合数字孪生技术建立了三相三柱式变压器内部无故障的孪生模型,基于动态时间规整算法提出新的故障特征量,提出早期故障保护方案。首先,利用实体设备的结构参数与实时的电气量,建立不同运行工况下的状态空间模型。然后,通过实际数据对孪生模型进行修正,使虚拟世界与物理世界实现同步,综合使用离散迭代法和Z变换法求解模型。其次,利用动态时间规整算法量化预测量与实测量的差异,以此作为故障特征量,并设计新型的故障保护方案,提高故障辨识的灵敏度。最后以三相三柱式变压器为例,通过ANSYS仿真和动模实验验证了所建模型的正确性,通过多次实验结果证实所提故障判据的有效性。     

新一代智能变电站通信网络及管理系统方案

通过分析新一代智能变电站网络管理的特点和功能需求,对电信网络管理体系结构和功能模型进行裁剪,提出新一代智能变电站通信网络管理系统的整体框架和功能部署方案。研发了网络拓扑自动成图、业务自动发现和创建、物理回路与虚回路相结合可视化等关键技术。结合绍兴枫桥变电站工程实例,验证了方案的可行性。方案推广应用后,将提升智能变电站网络运维能力,降低网络运维成本。     

Fresh forecasts [wind power forecasting]

Wind power forecasting falls broadly into two headings: statistical or physical modelling. Statistical modelling makes no real attempt to model the physical processes that drive the wind, but relies on previous wind speed patterns over time to make a prediction. In contrast, physical modelling tries to understand the physical processes that drive the wind, such that with sufficient input data, a model of the physical system can make a prediction some time into the future. In practice, a combination of statistical and physical modelling is used to provide an optimum wind power forecast over a time-horizon that may stretch out to 48 hours or more. To this end, a range of different 'model chains' can be used to forecast wind power.     

Simulating winds and floods-regional weather-river prediction andregional climate research

The authors at the University of California Lawrence Livermore National Laboratory (UC-LLNL) developed a coupled modeling system. The system simulates regional-scale weather, land-surface processes, and river flow using large-scale atmospheric data and land surface terrain information as input. This Coupled Atmosphere River Flow Simulation (CARS) system consists of the mesoscale atmospheric simulation (MAS) model coupled with a soil-plant-snow (SPS) model, our Automated Land Analysis System (ALAS) and a physically-based fully distributed surface hydrology and river flow model, TOPMODEL. The MAS model is a primitive-equation, limited-area model. It includes a third order accurate advection scheme and physical processes for: (1) precipitation and thermal forcing due to deep convective clouds and stratiform clouds; (2) solar and terrestrial radiative transfer within the atmosphere, and (3) turbulent transfer at the Earth's surface and within the atmosphere. Interactions between the atmosphere and land-surface are computed using the SPS model. It is interactively coupled to the MAS. The SPS keeps track of hydrologic variables such as water stored in the snowpack that is crucial for assessing the available water resources. The ALAS provides topographic properties, such as river networks and watershed areas, at specified resolutions, using digital elevation model data     

Laboratory investigation of a distance-protection technique for double circuit lines

A novel digital distance scheme has been implemented on a 32-bit digital signal processor board. The scheme is tested on a physical model of double circuit lines of equal impedance with a source at each end. Two relays instead of four are proposed for the two lines. Each relay is fed by three voltage and six current signals. The technique is based on the comparison of the measured impedance of the corresponding phases. Tests conducted on the physical model for various faults show that high fault resistance, current in-feed, balance-point location, out-of-step operation, and far-end faults are solved. Moreover, 100% of the line is protected.     

MgO微膨胀混凝土自身体积变形的双曲线模型

本文通过研究 ,在试验的基础上提出了符合MgO微膨胀混凝土自生体积变形特性的双曲线模型 ,用于表述MgO砼的自生体积变形特性。该模型的物理意义明确 ,表达简单 ,参数易于推求。同时 ,模型的拟合与试验成果是相吻合的 ,并应用于实时分析 ,计算值与实测值比较吻合