适应风电接入的异步联网高压直流输电系统自适应调频控制策略

大规模风电接入高压直流送端系统将导致系统惯量降低,送端系统调频能力不足。为充分挖掘直流和风电协同调频的潜力,提高含风电高压直流送端系统的调频性能,提出一种基于频率轨迹规划的异步联网高压直流输电系统自适应调频控制策略。分析了含风电高压直流送端系统的频率控制特性;综合考虑风电主动频率支撑和直流辅助频率控制,以频率偏差和频率变化率为量化指标,生成参考频率轨迹;在此基础上,对频率轨迹进行区域划分,以参考频率轨迹为基准,实现高压直流输电对送端系统频率的自适应调节。基于MATLAB/Simulink平台搭建改进的两区域4机模型进行仿真分析,验证了所提策略的有效性和优越性。     

抑制直流送端系统暂态过电压的直流和风电控制参数协调优化

为抑制风电经高压直流外送方式下的直流送端系统暂态过电压,提出一种直流和风电控制参数协调优化方法。首先,从整流站与风电场之间的无功转换角度分析了直流送端系统暂态过电压的产生机理,进而从系统无功特性入手研究了直流整流侧、风电转子侧变流器控制参数影响暂态过电压的机理,为抑制暂态过电压的控制参数协调优化提供了理论依据。然后,构建了以直流送端系统暂态过电压峰值最小为目标的优化模型,通过联合调用的方式,可在电磁暂态模型准确模拟交直流系统电磁暂态过程的基础上,进一步采用改进粒子群优化算法协调优化直流和风电控制参数,从而有效抑制直流送端系统暂态过电压。最后,通过修改后的4机11节点系统和新英格兰39节点系统的仿真分析,验证了所提方法的有效性和准确性。     

基于预测虚拟转矩控制的DFIG并网逆变方法

针对双馈风力发电机组(DFIG)高性能并网控制问题,提出一种DFIG并网逆变系统预测虚拟转矩控制方法。虚拟转矩的概念衍生于直接转矩控制中的电磁转矩,是由DFIG的转子磁链和电网虚拟磁链合成产生的。在建立DFIG并网逆变系统数学模型的基础上,分析了不同扇区中电压矢量对系统虚拟转矩、转子磁链的影响趋势,选取一个包含两个有效电压矢量和一个零电压矢量的三矢量序列,并给出功率无差拍跟踪时的矢量作用时间求取方法。最后,基于55 kW双馈风力发电实验样机对所提预测虚拟转矩方法进行性能验证。实验结果表明,该方法可实现DFIG系统平滑、无冲击并网,保证了并网接入点的动、稳态电能品质。     

海上风电场并网柔直系统的故障穿越协调控制策略

分析了基于H桥换流单元与集中式斩波电阻的多电平集中式卸荷电路(dynamic braking resistor,DBR),介绍了其结构拓扑、参数设计与控制方法,并对比模块化多电平卸荷电路,验证其故障穿越(fault ridethrough,FRT)性能。针对海上风电场并网柔性直流输电系统,结合双馈与永磁直驱风场侧换流站的交流电压降压法,利用风电机组(wind turbine generator,WTG)自身功率调节能力,设计FRT协调控制策略,在保证系统故障穿越性能的前提下,缩减卸荷电路所需容量,适用于高压大容量场合。依据德国已投运Borwin1工程的参数,在PSCAD/EMTDC电磁暂态仿真软件中搭建三端柔性直流输电系统模型,验证了所提协调控制策略具有良好的FRT控制效果。     

大型风电场的集中功率控制策略研究

在分析变速恒频风力发电机组与大型风力发电场控制系统关系的基础上,提出风力发电场的集中功率控制策略。利用M atlab/S imu link环境,建立风电场功率控制系统的仿真模型。以风扰动为例,对风力发电场并网的有功和无功功率调节过程进行仿真研究。理论研究和仿真分析结果验证了风电场集中功率控制策略的可行性和有效性。     

适用于含多并联逆变器微电网联络线功率控制策略

基于下垂机制的含多并联逆变器微电网联络线功率控制策略的控制层级较多,层级间时间尺度相差较大,导致其暂态响应较差,应对本地负荷波动或下垂系数调整等扰动的能力不强.针对以上问题,提出了一种新型的含多并联逆变器微电网联络线功率分层控制策略.一层分散控制采用电压滤波跟踪误差的方法对系统公共耦合点(Point of Common...     

Operation and control of coupled nonequilibrium disk MHD generator and inverter system under power line fault condition

Numerical simulations of detailed time‐dependent behavior are performed on a simulation model in which a coupled system of nonequilibrium disk MHD generator and line‐commutated inverter is connected to an infinite bus through the transmission line, showing that continuous operation of the system is usually possible even when a power line fault occurs near the system. Then, time‐dependent swing simulations are carried out on another simulation model in which the MHD/inverter system and a synchronous generator are connected in parallel to an infinite bus through the common transmission line, revealing that the rotor angle swing of the synchronous generator caused by the power line fault can be effectively suppressed by the fast output power control of the MHD/inverter system. © 1999 Scripta Technica, Electr Eng Jpn, 127(3): 13–24, 1999     

Compensation for harmonic currents and reactive power in wind power generation system using PWM inverter

In recent years, awareness of environmental problems is growing, and the price of electric power purchased by electric companies has been expensive for power plants utilizing natural energy. Thus, the introduction of wind power generation is being promoted in Japan. Generally, squirrel‐cage induction machines are widely used as generators in wind power generation systems because of their small size, light weight, and low cost. However, the induction machines do not have a source of excitation. Thus, inrush currents and instantaneous voltage drops occur when the generator is directly connected to a power grid. To reduce the inrush currents, an AC power regulator is used. Wind power generators are frequently connected to and disconnected from the power grid. However, when the inrush currents are reduced, harmonic currents are caused by phase control of the AC power regulator. And the phase control of the AC power regulator cannot control the power factor. Therefore, we propose the use of the AC power regulator to compensate for the harmonic currents and reactive power in a wind power generation system, and demonstrate the validity of this system by simulated and experimental results. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 154(2): 58–67, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20254     

大型并网型风光互补发电系统的协调控制

针对大型并网型风光互补发电系统中,系统最大输出功率大于给定功率时,风力发电子系统和光伏发电子系统功率如何协调的问题,提出了一种功率协调控制方法。在该方法中,采用分级递阶控制结构,上级决策单元为功率协调控制器,下级决策单元为两个子系统。根据系统并网效益和输出功率平滑性构建目标函数,采用带精英策略的快速非支配排序遗传算法(NSGA-Ⅱ)对风力发电子系统和光伏发电子系统的输出功率进行多目标优化,协调控制子系统的发电功率。仿真结果验证了该功率协调控制方法的有效性。     

Control and protection scheme of HVDC system with self‐commutated converter in system fault conditions

For extending self‐commutated converter application to future trunk power systems, it is important to develop a stable operation scheme as well as to realize substantial cost reduction through coordinated system and control design. Suppression controls of converter overcurrent and dc overvoltage in various system fault conditions are essential in order to ensure stable operation and cost reduction of HVDC systems with voltage source type self‐commutated converters. Converter control and protection schemes which include such suppression controls have been developed, employing CRIEPI's ac/dc Power System Simulator test and EMTP analysis. This paper first discusses the cause of converter overcurrent at ac system faults, considering the effect of PWM pulse number and converter control speed. Continued operation has been achieved by adding a new overcurrent suppression scheme to the converter control. In the case of a dc line grounding fault, the selection of the grounding circuit constant and the adoption of a high‐speed converter control practically ensure the reduction of dc overvoltage while suppressing converter overcurrent. The converter block and restart sequence after a dc fault, which is coordinated with dc circuit breaker operation, enables stable recovery of HVDC transmission as fast as the usual line‐commutated HVDC system. © 2000 Scripta Technica, Electr Eng Jpn, 132(2): 6–18, 2000     

并网双馈异步风电机组模糊自适应控制

介绍了双馈感应风力发电系统运行的基本原理。在变风速下,根据最大功率跟踪控制原理,利用发电机输出功率误差和发电机的转速误差,提出用模糊控制器代替风速测速仪来跟踪发电机的最佳转速,保证在额定风速下,使风机运行在最佳叶尖速比,风能利用率最佳,避免了湍流塔影等因素对风速测量的影响。同时,在外环功率PI调节器中,引入模糊控制来提高在额定风速下双馈感应发电机功率解耦的快速跟踪。最后,通过对整个风电系统包括风力机、双馈感应电机(含网侧及转子侧变换器)、控制器(含网侧及转子侧控制器)进行建模及仿真来验证模糊控制策略的可行性。     

一种新颖的单相光伏并网发电系统控制策略

针对两级式单相光伏并网发电系统,提出一种新颖的系统控制策略。在传统的双环控制策略基础上加入功率跟踪环节,提高逆变器输出电流对前级功率输入变化时的响应速度;采用BP神经网络自整定PI控制器实现电流闭环的跟踪控制,提高系统动态性能,改善功率突变时逆变器的电流波形,提高系统运行效率。利用MATLAB/simulink对提出的控制策略进行仿真研究,结果表明该系统能可靠稳定地向电网传输电能。最后在2 k W实验样机上进行实验验证,结果证明控制策略和仿真结果的正确性。     

Adaptive fractional integral terminal slidingmode power control of UPFC in DFIG windfarm penetrated multimachine powersystem

With an aim to improve the transient stability of a DFIG wind farm penetrated multimachine power system (MPN), an adaptive fractional integral terminal sliding mode power control (AFITSMPC) strategy has been proposed for the unified power flow controller (UPFC), which is compensating the MPN. The proposed AFITSMPC controls the dq- axis series injected voltage, which controls the admittance model (AM) of the UPFC. As a result the power output of the DFIG stabilizes which helps in maintaining the equilibrium between the electrical and mechanical power of the nearby generators. Subsequently the rotor angular deviation of the respective generators gets recovered, which significantly stabilizes the MPN. The proposed AFITSMPC for the admittance model of the UPFC has been validated in a DFIG wind farm penetrated 2 area 4 machine power system in the MATLAB environment. The robustness and efficacy of the proposed control strategy of the UPFC, in contrast to the conventional PI control is vindicated under a number of intrinsic operating conditions, and the results analyzed are satisfactory.     

高压直流控制保护系统控制总线应用分析

对不同的高压直流控制保护系统控制总线结构进行分析,对其特点及功能应用进行总结。     

Fault Ride-Through Capability Enhancement of VSC HVDC connected Offshore Wind Power Plants

To achieve active control of the AC voltage magnitude of wind power plant(WPP) collector network and improve the fault ride-through (FRT) capability,an FRT scheme based on feed forward DC voltage contr...     

基于虚拟同步控制的双馈式风机组并网控制策略的仿真分析

针对双馈式风电机组经出口逆变器并网时缺乏惯性和阻尼会导致电网稳定性受到冲击的问题,首先简述了基于虚拟同步控制的双馈式风机整体控制策略;然后分别介绍了整体控制策略中的转子侧和网侧逆变器的控制策略,并搭建了含网侧虚拟同步控制的双馈式风机组模型;最终针对电网的故障工况及不同运行风速,通过MATLAB/Simulink对该模型进行仿真分析,与原始的双馈式风机模型仿真结果进行对比。验证了含网侧虚拟同步控制的双馈式风机比采用传统控制策略的双馈式风机组具有更优异的调节特性。     

适应大容量直流接入弱受端的直流极控系统优化控制方法

大容量直流接入较弱受端系统,换流母线电压相对敏感,故障扰动易引起直流换相失败甚至发生连续换相失败。针对弱受端交流故障恢复过程中可能出现的连续换相失败问题,提出了根据交流系统和直流系统关键变量,在线计算调整低压限流功能直流电压上限值的方法,使直流的恢复速度能适应交流系统的恢复状态,避免连续换相失败的发生;提出了逆变站调节器配合和分接头控制的优化方法,使逆变站进入定直流电压控制模式,能在一定程度上减小远端故障引发换相失败的概率。利用与实际直流工程极控系统完全一致的仿真模型进行仿真验证,仿真结果表明:所提出的优化方法可行、有效,能适应弱受端系统对于抵御换相失败的需求,有利于改善交直流系统运行稳定性。     

连接低惯量系统的VSC-MTDC的自适应下垂控制

对于连接低惯量交流系统的多端柔性直流输电(VSC-MTDC)系统,当系统发生大扰动时会造成频率变化,为了给交流系统提供虚拟惯量,在换流器控制系统中加入P-?下垂控制;为了进一步抑制频率波动,设计VSC-MTDC系统的自适应下垂控制,可以在更大程度上利用换流器容量,快速调节有功平衡,减小直流电压波动。在PSCAD/EMTDC仿真软件中建立三端模型,对比分析主从控制、下垂控制和自适应下垂控制对交流系统频率和直流电压的影响。仿真结果表明,加入了P-?下垂控制可以有效抑制交流系统频率变化,采用自适应下垂控制可以增强抑制的效果,减小直流电压波动,提高系统稳定性。     

Design of passivity‐based stabilized control of grid‐connected inverter system with LCL filter

Instabilities due to mutual interactions between inverters and grid impedance are observed sometimes. This paper proposes a new stabilization method, which improves the output frequency impedance characteristics, satisfying the Nyquist stability criterion. The principle is that the output impedance is designed to be passive with the feedfoward loop characteristics and the system is stable even for an unknown grid system impedance. The design principle for the proposed stabilization method is described and investigated and validated on the basis of simulation and experimental results.     

并网型变速恒频风力发电系统仿真及实验研究

在对双馈电机的数学模型进行深入研究的基础上,进而提出一种双闭环空载并网控制策略,并且给出了控制器的设计方法。对提出的控制策略搭建了仿真模型,并且在实验平台上进行了验证。仿真和实验结果表明,控制系统不仅实现了在变速情况下的柔性平滑并网,而且在并网后可以对有功功率和无功功率进行解耦控制。