Due to the challenges confronting the existed AC power system, the research on the MTDC networks is of significant importance both theoretically and practically. This paper presents the concept of introducing the application of MTDC technology in the distribution network. A five-terminal VSC and ling-topology based DC distribution network is proposed. Control strategy based on the above configuration with emphasis on the control of the bidirectional DC/DC convener is also put forward. Finally, the advantages obtained with such a DC distribution network are demonstrated by simulations using MATLAB/Simulink in different operation modes.

停电事故后电力系统恢复过程主要包括网架修复和负荷恢复,合理的黑启动方案对加快电力系统的恢复有重要作用。当电网由于故障全停之后,孤岛运行的电动汽车充放储一体化电站作为电网中的一种分布式电源可以参与黑启动。介绍了一体化电站的结构和功率特性,分析了一体化电站作为黑启动电源与传统黑启动方式相比的优越性。基于黑启动的基本原理,建立了一体化电站满足潮流约束和系统安全约束的黑启动模型,制定了一体化电站参与黑启动的具体方案。将建立的模型应用于含有16座一体化电站的区域电网,采用遍历算法对问题进行求解,得到了区域电网的恢复过程,验证了所提出一体化电站黑启动方案的可行性。

根据一体化电站信息流分布情况,通过监控系统对一体化电站及车载终端的详细参数进行采集。利用物联网(IOT)和GPS技术,可对一体化电站内外电池工作状态进行状态监控和故障处理。对一体化电站与电网之间的交换功率和一体化电站的能量水平进行分析及融合。根据上述融合信息,结合一体化电站和电网运行信息,提出一种新型的并网控制策略。实际算例表明,基于信息融合技术的并网控制策略对一体化电站和电网的正常运行有着积极作用。

风电场大规模接入电网可能增加区域电网低频振荡和风电机组轴系扭振的风险,研究风机建模及扭振特性是保证电力系统安全稳定的重要课题。以失速型风电机组为例,建立基于三质量块轴系模型的单机对无穷大母线系统小信号模型,并采用模态分析法探讨系统电气参数对失速型风电机组轴系扭振特性的影响。为方便不同机型及多机风电机组的扭振特性的拓展研究,系统各部分模型相对独立。在单机对无穷大母线系统模型的基础上建立简化失速型风电场多机小扰动仿真模型,研究风电场扭振模态的变化,MATLAB仿真验证了该模型用于风电机组轴系扭振问题研究的有效性和准确性。

With wind turbine system developing larger and lighter, the dimensions of time-varying complexity gradually increase. Meanwhile, the wind turbine loads suffer randomness, which results in stronger prolonged vibration. And then the stability of wind turbine system is seriously damaged. By integrating wind turbine model, deterministic load model and the impact of stochastic load, this paper establishes first-passage model with stochastic load. And combined with the electrical dynamic model of wind turbine, a unified electromechanical dynamic model is built up. By using stochastic averaging method of quasi-non-integrable- Hamiltonian systems, it sets up relevant Hamilton function and the stochastic model of one-dimensional It?o diffusion process, which will lay a good foundation for following stability and reliability study. With an example of a domestic unit of 750 kW wind turbine, the corresponding unified electromechanical dynamic model is established. And the first-passage phenomenon is verified by a simulation in MATLAB. Simulation results show that the model has good applicability and operability.

Traditional ac distribution network is ushering a new era of transformation toward dc, providing significant solution to its insufficient current carrying capacity, increasing fault currents, poor power quality, difficulty in flexible integration of large-scale renewable energy sources, etc. To address these issues this paper intends to open up an overview of the dc distribution network trends and present technical superiority analysis for multi-terminal dc (MTDC) distribution network. On this basis, MTDC distribution architectures based on voltage sourced converter (VSC) have been proposed and applied with reliability and controllability under consideration, such as hand-in-hand topology, dual-ring topology, half-ring topology and radial-type topology. Furthermore, performance of MTDC distribution networks is discussed and theoretically validated: high voltage stability, short recovery time, large power capacity, flexible power flow controllability, high power quality, plug-and-play functionality for dispersed renewable sources, etc. Besides, two kinds of control schemes with central control or not are discussed and energy optimization of MTDC network is focused. Last of the paper discusses current DC distribution projects and projects under construction. To sum up, MTDC distribution networks are superior to its ac counterpart, while many technical and practical problems remain unsolved.

针对目前电池参数特性研究的局限性,提出一种基于多元参数融合曲面的充电特性分析方法.采用基于GNL的改进电池模型,通过参数辨识实验得到电池参数系数,结合电池的充放电特性,将电池端电压、荷电状态SOC、电流及充电时间等多元参数进行融合设计,建立电池参数的三维曲面.该曲面不仅能直观形象地反应电池各参数间的非线性函数关系,还可通过平行截取曲面对电池恒压、恒流等充电方式的充电特性进行分析,其分析结果与EMTP中的仿真结果基本一致.

Because of the large scale wind farms occupied a larger area,and containing a large number of wind turbines,wake effects and wind delay among wind turbines have a certain impact on wind farms.Based on Weibull distribution function,the stochastic wind model and wind turbine mathematical model of wind farm were established in this paper.The small signal stability model of wind farm was created,and the complex wind farms operation was comprehensively analyzed.The linear-distribution and cross-distribution of three fan system were simulated,and the changing of eigen-values under different distribution methods was analyzed.It was found out that wake effects and the time-delay have little influence to small signal stability.The stability margin of wind farms via reasonable distribution of fans can thus be increased.

合理的控制策略可以使电动汽车智能充放储一体化电站在容量充足的情况下为电网提供无功,实现无功的就地补偿。基于电动汽车智能充放储一体化电站的等效电压源运行特性,通过控制算法使其运行于等效发电机或静止无功发生器(SVG)容性模式。研究电动汽车智能充放储一体化电站变流器的无功电压调节特性,进而基于无功电压调控提出了电动汽车智能充放储一体化电站的增值策略和紧急控制策略。实际算例分析表明,电动汽车智能充放储一体化电站具有良好的无功电压控制能力。

The equivalent simplification of wind turbines in the large scale wind farm has crucial in-fluence on wind farm studies.This paper proposed a dynamic equivalent method of wind farm.In this method,the slip coherency was used as the clustering rule which reflected the operating point of wind turbines.By extracting the clustering index reflected the slip dynamic response,the wind turbines were dynamically clustered.Then,by taking a weighted average,the same cluster wind turbines were aggregated and the equivalent model of coherent turbines wad gained.And the wind farm was equivalent to several equivalent turbines.Finally,the detailed model and equivalent model of wind farm was built in Matlab/Simulink environment.The simulation results verified the effec-tiveness of clustering index and the accuracy of wind farm equivalent model separately.

With electric power network getting larger and more complex, it is unprecedented vulnerable and modern society is faced with higher blackout risk The stable and reliable operation of a power system is necessary after major emergencies (or blackouts) following a major system event. The intelligent integrated station (IIS), providing energy and changing batteries for EVs, has the ability to separate and isolate itself from the power grid seamlessly with little or no disruption to loads in the station. Then, when the utility grid returns to normal, the IIS resynchronizes and reconnects itself to the grid in an equally seamless manner. According to conventional system restoration after a black-out, the control principles of black-start for intelligent integrated station are put forward. The build-up strategy is used to restore power system with IIS, which includes the process of restoring separated parts (islands) in the power system and interconnecting them afterwards. The control of IIS with energy storage system will deal with building isolated network, forming and operating island, and connecting island and re-synchronization with upstream network or grid system. A model based on the black-start principle proposed above is developed and the model is applied in a regional power grid.

While EVs partially rely on electricity from the power grid, they have the potential to be used as generation resources to provide energy and ancillary services into the grid. But the existing EVs' charge and exchange system has significant room for improvement through automation and information management, condition monitoring, and battery management, especially on the grid-connected control system. Therefore, a novel EV's intelligent integrated station (IIS) including bidirectional converters, exchange system, cascaded system and dispatch center, is proposed in this paper to pave the way for a more sustainable power grid. In this paper, we explore both the battery management system (BMS) and control strategy of grid-connection based on the technique of multi-source information fusion, focusing first on batteries information in IIS and then on operational information of power grid from energy management system (EMS). Based on the information in control center received from BMS and EMS, an effort is made to develop a novel control strategy of grid-connection to well take into account of the operational state of power grid and battery energy level of IIS, and further to improve the efficiency of power/energy flow between IIS and power grid. Moreover, an algorithm for power flow estimation between IIS and power grid based on Kalman filtering theory is proposed to get accurate information. Actual operation results indicate that the proposed system is an ideal power interface for EVs and power networks.

Taking fixed speed induction generator (FSIG) unit for example, a wind turbine model including three mass equivalent model of shafting system is established. On this basis a small signal simulation model for wind farm composed of FSIGs is built to research the torsional vibration pattern occurred in homotype wind farm and its correlation factor, and the torsional vibration patterns of wind farms with different layouts and numbers of wind turbines are compared. Comparison results show that in the shaft torsional vibration pattern among wind farm units the double resonance peak phenomenon appears, and the increase of wind turbine number makes the real part of the eigenvalue of torsional vibrating pattern trending toward positive axis and corresponding damping ratio is decreased;the torsional vibration transferring among wind turbines in the same wind farm exists, and the number and layout of wind turbines in the wind farm influence the small signal stability of the wind farm.

After a blackout, power needs to be restored as quickly and reliably as possible to reduce economic loss, and consequently, detailed restoration plans are necessary. According to the basic black-start method, the control principles of black-start for intelligent integrated station (IIS) are put forward. To speed up the restoration process, the whole system containing intelligent integrated stations is partitioned into several subsystems which are restored in parallel. These independent subsystems will later be synchronized to restore the original power system seamlessly through virtual connection control. A model based on the black-start principle proposed above is developed. At last, a regional power system containing 16 intelligent integrated stations is employed as an example to verify the validity of the proposed approach.

Compared to reactive power/voltage index and standard operation procedure (SOP) of power system, the reactive power/voltage index of charging-discharging-storage integrated station is defined, which includes voltage margin and voltage adjustable capability of integrated station ((ISVM & ISVAC). And then the reactive power compensation control strategy of integrated station is put forward and proved to be lossless in power. According to the reactive power regulation characteristic, a reasonable reactive power distribution between shunt integrated stations can be realized by the reactive power/voltage optimization algorithm. And the synthesis optimization can be achieved when AVC applied into integrated station, which will bring value-added benefit to power quality and greatly improve the grid reliability.

Battery energy and power density are limiting factors in the development of electric vehicle systems, particularly in the context of wide-range charge and exchange needed for traction batteries of electric vehicles. A novel battery management system combining the technology of radio frequency identification, internet of things and GPS is put forward to guarantee safe operation. The EV's intelligent integrated station proposed in this paper not only charges electric vehicles' traction batteries, but also functions as an interface between vehicles and the grid. According to the information flow of the intelligent integrated station and grid operating conditions gathered by monitoring system, the strategy of grid-connected control is developed using information fusion technology. Actual operation results are provided to illustrate the optimality of the proposed grid-connected control strategy to support power grid.

Energy facilities for electrical vehicles (EVs)are the key to promotion development for EVs.A new design proposal named Charging-Discharging-Storage Integrated Station with multi-func-tions of charging,swapping,storage is put forward,which can make full use of idle batteries and batter-ies that out of performance by rearrange those batteries to be part of energy storage system.The energy storage system can provide energy for the upper power network and also absorb energy from the power network.On the basis of analyzing characteristics of the Charging-Discharging-Storage In-tegrated Station,operation procedures for the integrated station is designed,including seven main points as follows:general principles,dispatching center,multi-function converter,char-ging-replacing system for batteries,echelon utilization system for batteries,power supply system for integrated station,abnormal situation and accidents handling.For each main point,descrip-tion of devices,operational process and points for attention are discussed detailedly.

Pow er system area control error( ACE) is one of the major targets of the pow er system standard operating procedure( SOP). This paper defined the integrated station aera control error( ISACE) quota to perform researches on the pow er-frequency control strategy of integrated station. Then the value-adding control and emergency support control stategy w ere proposed according to the ISACE indicators and the running mode of integrated pow er station. In the end,this paper made quantitative analysis on the operating data of real pow er system and proved the adjustment effect of integrated pow er station on pow er system ACE.

电动汽车充放储一体化电站的设计充分利用了电池的储能价值,与电网调度中心配合,实现电网与电站之间的灵活能量互动,是未来电动汽车供能设施的发展方向.考虑电网5个运行状态,设计了与之相关的一体化电站正常运行、保护运行以及孤岛运行3种模式,并讨论其对电力系统频率偏差、区域控制偏差、电压可调能力、电压暂降以及功率振荡等5个运行指标的调整能力,探讨了一体化电站运行状态集,较为完备地描述了一体化电站与电网运行状态的相关模式.

Provides a new energy unit flow control strategy,SOC estimation can estimate of the overall storage capacity in EV integrative station effectively.It can combine of grid EMS station within the SCADA system,control the complementary support between EV integrative station and the grid by two-way controlled inverter.This control strategy has a good prospect in improving grid security,flexibility as well as building a smart grid.