含VSC-HVDC的交直流混合系统的状态估计解耦迭代算法

针对以电压源换流器(Voltage Source Converter,VSC)为基础的新一代高压直流输电,推导了直流系统的数学模型,以状态估计为着眼点,建立了交直流混合系统的状态估计模型,并在此基础上提出了一种解耦迭代算法。该算法根据雅克比矩阵的特点,运用数学方法对交流子系统和直流子系统进行严格解耦,从而将交直流混合系统分为交流子系统和直流子系统2部分,实现了交、直流子系统的分开迭代求解。计算过程中未做任何假设,因此完整计及了交、直流子系统间的耦合性,算法精度高,同时该算法在编制程序时可以充分利用纯交流系统的状态估计程序,因此具有良好的继承性。IEEE 14、IEEE 30、IEEE 57节点测试系统的仿真结果表明了所提算法的有效性。     

交直流混合微电网多时间尺度协同控制

为了更好地将可再生交直流电源并入电网,提出了一种适用于交直流混合微电网的多时间尺度协同控制方法,该交直流混合微电网由一个交流子网和一个直流子网组成,它们之间通过双向功率转换器(bidirection-al power converter,BPC)连接.该控制方法在三个时间尺度上依次稳定功率波动,在第一时间尺度中,当某子...     

电力系统机电暂态和电磁暂态数字混合仿真

简要介绍了混合仿真的基本原理．对国内外研究状况进行综述,从工程应用角度对混合仿真涉及的关键技术进行分析和评价,并就混合仿真软件开发过程中需注意的若干事项进行讨论。最后指出,基于成熟的机电暂态和电磁暂态软件开发离线混合仿真程序具有广阔的前景和工程应用价值。     

基于RTDS-PXI的电磁-机电暂态混合实时仿真研究

提出了基于RTDS—PXI的电磁一机电暂态混合实时仿真方案,其采用并行的数据交互方式,将运行在RTDS上的电磁暂态程序和自主开发的机电暂态程序通过PXI进行实时接口．实现了电磁一机电暂态混合实时仿真。最后在搭建的RTDS—PXI混合实时仿真平台上进行了与小规模全电磁暂态仿真的对比分析,结果表明所提出的方案是可行、有效的。     

基于小波分析的枯水径流多时间尺度分析

以密云水库1956～2002年共47 a的年最枯一月径流量过程为例,对枯水径流序列进行小波变换并分析其多时间尺度演变特性.结果表明,枯水径流序列具有明显的多时间尺度特征,资料序列具有时间尺度为16、10、5 a的主要周期,2015年前后为枯水流量极小年份.     

电力系统机电/电磁暂态仿真数据转换系统

针对目前电力系统机电暂态仿真与电磁暂态仿真各自相对独立的现状,从电力系统机电暂态/电磁暂态转换仿真的需求出发,提出并编程实现了一种基于PSS/E和EMTP软件的电力系统机电/电磁暂态仿真转换系统,该系统可以直接将机电暂态仿真数据转换为电磁暂态仿真数据,为机电暂态与电磁暂态两种原本相对独立的仿真搭起了桥梁。并以实际上海电网为例,结果表明该系统能准确地实现电力系统机电暂态仿真到电磁暂态仿真数据的成功转换。     

规模化光伏电站与电网暂态交互影响定量分析

在电力系统暂态安全定量分析软件平台FASTEST(Fast Analysis of Stability using the Extended equal areacriterion and Simulation Technologies)上以研究规模化光伏电站接入系统后的稳定性分析为目的,建立了一个完整而且适合系统安全稳定分析的并网光伏电站机电暂态模型。基于FASTEST特有的暂态稳定量化分析功能,对并网光伏电站被浮云遮挡和系统侧发生扰动这2种典型情况进行仿真分析,从对系统暂态功角稳定性、暂态电压稳定性和暂态频率稳定性的影响的角度,探讨光伏电站与常规电源在影响电网运行特性方面的区别。结果表明,光伏电站并网后对系统暂态频率稳定性影响最为严重,相比较于带有励磁和调速系统的同步发电机,光伏电站在网侧故障时的暂态响应特性更为剧烈。     

宜昌站主汛期流量及水温变化多时间尺度分析

以宜昌站1956～2002年主汛期为例,采用复Morlet小波分析了流量、水温序列多时间尺度变化规律,并根据主周期预测了未来变化趋势.结果表明,主汛期流量、水温序列均存在三类时间尺度的周期,各周期尺度下小波变换系数基本为正负对应出现,呈偏丰-偏低、偏枯-偏高交替变化规律,且将持续到2015年.     

应用机电暂态程序判断直流换相失败的分析

换相失败是直流系统常见的故障之一,连续换相失败或者多回直流同时换相失败,将会严重危害交直流系统的稳定运行。因此,换相失败的判断是一个非常重要的问题。机电暂态程序具有模型简单、仿真规模大、计算时间短等特点,而且仿真精度能够满足电力系统的计算要求,常常用于分析大型交直流混合电网的换相失败原因。在阐述换向失败的机理及其影响因素的基础上,分析了机电暂态程序的直流模型和换相失败判据,并且通过一算例计算,比较了国内常用的机电暂态程序BPA和PSS/E的仿真结果,着重分析了两个程序用于换相失败研究的范围。     

Modeling of hybrid photovoltaic/wind/fuel cells power system

In this paper, identification and modeling of a hybrid photovoltaic/wind/fuel cells power system is presented. This system comprises also a battery storage supplying a load via an inverter. The identification of each subsystem has been made and then the proposed system is modeled and simulated under Matlab/Simulink Package. The power control of the hybrid system is introduced by using LabVIEW Software. The mathematical model topology and its power management of the global system with battery bank system are significant contributions of our work. The proposed control strategy has been experimentally implanted and practical results are compared to those obtained by simulation under the same metrological conditions, showing the effectiveness of the proposed hybrid system.     

Modeling and simulation of a grid-connected PV generation system for electromagnetic transient analysis

This paper addresses modeling and simulation of a grid-connected photovoltaic system (GCPS) to analyze its grid interface behavior and control performance in the system design. A simple circuit model of the solar array is used to easily simulate its inherent characteristics with the basic specification data. Detailed power and protection control of the GCPS as well as its electrical circuits have been represented by user-defined and built-in components to take into account transients in normal and fault conditions, which are dominated by its power electronic controller. The model has been described with the reference to and implemented in PSCAD/EMTDC, a power system transient software package. Extensive simulation results are presented and analyzed to validate that the proposed simulation model is effective for control and protection performance evaluation of the GCPS in terms of electromagnetic transient analysis.     

A synchronous/permanent magnet hybrid AC machine

In this paper, a synchronous/permanent magnet hybrid (SynPM) machine is presented. It is shown that the machine has good power density and efficiency, and that the machine has true field regulation capability. The principle of operation, finite element analysis and simulation of this new machine are investigated in the paper     

Research on multi-time scale doubly-fed wind turbine test system based on FPGA + CPU heterogeneous calculation

As the proportion of renewable energy increases, the interaction between renewable energy devices and the grid continues to enhance. Therefore, the renewable energy dynamic test in a power system has become more and more important. Traditional dynamic simulation systems and digital-analog hybrid simulation systems are difficult to compromise on the economy, flexibility and accuracy. A multi-time scale test system of doubly fed induction generator based on FPGA + CPU heterogeneous calculation is proposed in this paper. The proposed test system is based on the ADPSS simulation platform. The power circuit part of the test system is setup up using the EMT (electromagnetic transient simulation) simulation, and the control part uses the actual physical devices. In order to realize the close-loop testing for the physical devices, the power circuit must be simulated in real-time. This paper proposes a multi-time scale simulation algorithm, in which the decoupling component divides the power circuit into a large time scale system and a small time scale system in order to reduce computing effort. This paper also proposes the FPGA + CPU heterogeneous computing architecture for implementing this multitime scale simulation. In FPGA, there is a complete small time-scale EMT engine, which support the flexibly circuit modeling with any topology. Finally, the test system is connected to an DFIG controller based on Labview to verify the feasibility of the test system.     

Modeling and analysis of an FC/UC hybrid vehicular power system using a wavelet-fuzzy logic based load sharing and control algorithm

Fuel cell (FC) systems are potentially promising candidates as alternative energy sources for use in vehicular applications. The natural advantages of hybrid power sources may be effectively utilized to improve the efficiency and dynamic response of a vehicular system. Fuel cell (FC) and ultra-capacitor (UC) based hybrid power systems appear to be very promising for satisfying high energy and high power requirements for vehicular applications. In this paper, a FC/UC hybrid vehicular power system using a wavelet based load sharing and fuzzy logic based control algorithm is proposed. While wavelet transforms are suitable for analyzing and evaluating the dynamic load demand profile of a hybrid electric vehicle (HEV), the use of fuzzy logic controller is appropriate for the hybrid system control. The mathematical and electrical models of the hybrid vehicular system are developed in detail and simulated using MATLAB^®, Simulink^® and SimPowerSystems^® environments.     

Modeling and simulation analysis on parallel hybrid air-fuel vehicle

Based on the vehicle simulation software ADVISOR, the model of a parallel air-fuel hybrid vehicle was established, and the modeling of an air powered engine (APE), heat exchanger, braking air tank and control strategy were discussed in detail. Using the vehicle model, a hybrid vehicle refitted from a traditional diesel car was analyzed. The results show that for the New European Driving Cycle (NEDC), the Urban Dynamometer Driving Schedule (UDDS) and the Highway Fuel Economy Test (HWFET) driving cycle, the total reductions in fossil fuel consumption of the hybrid vehicle were 48.29%, 48.51% and 22.07%, respectively, and the emissions could be decreased greatly compared with the traditional diesel car, while the compressed air consumptions of the hybrid vehicle were 97.366, 85.292 and 56.358 kg/100 km, respectively. Using the diesel equivalent as the indicator of fuel economy, the hybrid vehicle could improve the fuel economy by 14.71% and 16.75% for the NEDC and the UDDS driving cycles and decrease by 5.04% for the HWFET driving cycle compared with the traditional car. The simulation model and analysis in this paper could act as the theoretical basis and research platform in optimizing the key components and control strategy of hybrid air-fuel vehicles.     

Modeling,control and simulation of an autonomous wind turbine/photovoltaic/fuel cell/ultra-capacitor hybrid power system

This paper focuses on the combination of wind turbine (WT), photovoltaic (PV), fuel cell (FC) and ultra-capacitor (UC) systems for grid-independent applications. The dynamic behavior of the proposed hybrid system is tested under various wind speed, solar radiation and load demand conditions. The developed model and its control strategy exhibit excellent performance for the simulation of a complete day. In the simulation, the solar radiation and power demand data are based on real world measurements, while the wind speed data are quasi-real because it is simulated based on special wind speed generation algorithms.     

Modeling and control of a wind fuel cell hybrid energy system

This paper describes a hybrid energy system consisting of a 5 kW wind turbine and a fuel cell system. Such a system is expected to be a more efficient, zero emission alternative to wind diesel system. Dynamic modeling of various components of this isolated system is presented. Selection of control strategies and design of controllers for the system is described. Simnon is used for the simulation of this highly nonlinear system. Transient responses of the system for a step change in the electrical load and wind speed are presented. System simulation results for a pre-recorded wind speed data indicates the transients expected in such a system. Design, modeling, control and limitations of a wind fuel cell hybrid energy system are discussed.     

Modeling,control and simulation of a photovoltaic /hydrogen/ supercapacitor hybrid power generation system for grid-connected applications

Hybrid renewable energy systems (HRES) should be designed appropriately with an adequate combination of different renewable sources and various energy storage methods to overcome the problem of intermittency of renewable energy resources. Focusing on the inevitable impact on the grid caused by strong randomicity and apparent intermittency of photovoltaic (PV) generation system, modeling and control strategy of pure green and grid-friendly hybrid power generation system based on hydrogen energy storage and supercapacitor (SC) is proposed in this paper. Aiming at smoothing grid-connected power fluctuations of PV and meeting load demand, the alkaline electrolyzer (AE) and proton exchange membrane fuel cell (PEMFC) and SC are connected to DC bus of photovoltaic grid-connected generation system. Through coordinated control and power management of PV, AE, PEMFC and SC, hybrid power generation system friendliness and active grid-connection are realized. The validity and correctness of modeling and control strategies referred in this paper are verified through simulation results based on PSCAD/EMTDC software platform.