A developed control strategy for mitigating wind power generation transients using superconducting magnetic energy storage with reactive power support

The fast variations of wind speed during extreme wind gusts result in fluctuations in both generated power and the voltage of power systems connected to wind energy conversion system (WECS). This paper presents a control strategy which has been tested out using two scenarios of wind gusts. The strategy is based on active and reactive powers controls of superconducting magnetic energy storage (SMES). The WECS includes squirrel cage induction generator (SCIG) with shunt connected capacitor bank to improve the power factor. The SMES system consists of step down transformer, power conditioning unit, DC–DC chopper, and large inductance superconducting coil. The WECS and SMES are connected at the point of common coupling (PCC). Fuzzy logic controller (FLC) is used with the DC–DC chopper to control the power transfer between the grid and SMES coil. The FLC is designed so that the SMES can absorb/deliver active power from/to the power system. Moreover, reactive power is controlled to regulate the voltage profile of PCC. Two inputs are applied to the FLC; the wind speed and SMES current to control the amount active and reactive power generated by SMES. The proposed strategy is simulated in MATLAB/Simulink®. The proposed control strategy of SMES is robust, as it successfully controlled the PCC voltage, active and reactive powers during normal wind speeds and for different scenarios of wind gusts. The PCC voltage was regulated at 1.0 pu for the two studied scenarios of wind gusts. The fluctuation ranges of real power delivered to the grid were decreased by 53.1% for Scenario #1 and 56.53% for Scenario #2. The average reactive power supplied by the grid to the wind farm were decreased by 27.45% for Scenario #1 and 31.13% for Scenario #2.     

应用于超导储能的功率调节系统

讨论了一种适用于超导储能(Superconducting Magnetic Energy Storage,简称SMES)的电流型功率调节系统.主电路设计采用了模块化结构,易于扩容;控制电路采用以主控DSP和MCU为核心的两级结构.利用瞬时功率检测方法所得到的有功功率和无功功率进行功率闭环控制.实验结果说明.功率调节系统能够在四象限内快速、独立地控制有功功率和无功功率.单机无穷大系统的三相短路实验表明,超导储能系统能够显著抑制发电机的功率振荡.     

SMES对STATCOM动态性能改善的研究

将超导磁储能(SMES)线圈引入基于电压源型逆变器(VSI)的静止同步补偿器(STATCOM)来阻尼电力系统低频振荡.超导磁储能线圈经过两象限三相直流-直流斩波器接入STATCOM前端的VSI.在附加储能装置--超导线圈的作用下,STATCOM能同时吸收或发出有功和无功功率,其动态性能得到很大的改善.在本文中,用电磁暂态仿真软件PSCAD/EMTDC对发生三相故障后电力系统的动态过程进行研究,并给出结果.结果表明,具有有功和无功功率控制能力的STATCOM-SMES组合补偿装置能有效地阻尼电力系统低频振荡,提高电力系统静态和动态稳定性,增强输电网的可靠性.     

超导电力磁储能系统研究进展(二)——能量控制装置

对电力系统中超导磁储能（SMES）装置采用的电力电子技术的一般结构与原理进行了综述。对其关键的功率调节系统（PCS）做了详细的讨论,并给出了一些模拟试验结果。最后针对我国研究现状,提出了PCS进一步发展的方向。     

电压型超导储能系统的统一直接功率控制方法

将PWM整流器的直接功率控制方法用于电压型超导储能系统的电压源型换流器，给出了新的开关矢量表，并提出了斩波器的直接功率控制方法。文中的电压源型换流器和斩波器的直接功率控制方法以有功功率为纽带，可对超导储能系统进行一体化的功率控制。仿真结果表明，该控制方法具有良好的控制性能，十分适用于电压型超导储能系统。     

基于DSP2812高温超导储能系统斩波器控制设计

电压型超导储能(Superconduction Magnetic Energy Storge,简称SMES)系统的斩波器用于对超导磁体快速稳定充放电。研究了SMES系统用斩波器充放电的工作原理,采用状态空间平均法建立其数学模型,并提出一种斩波器充电、放电的闭环控制方法。基于第2代高温超导磁体及其限流保护,搭建了斩波器实验系统,应用DSP2812处理器实现对超导磁体充放电的控制。实验结果表明,所应用斩波器控制方法的性能良好,可以满足SMES系统的要求。     

Enhancement of transient stability by fuzzy logic-controlled SMES considering communication delay

This paper presents a fuzzy logic-controlled superconducting magnetic energy storage (SMES) for the enhancement of transient stability in a multi-machine power system. The control scheme of SMES is based on a pulse width modulation (PWM) voltage source converter (VSC) and a two-quadrant DC–DC chopper using gate-turn-off (GTO) thyristor. Total kinetic energy deviation (TKED) of the synchronous generators is used as the fuzzy input for SMES control. Communication delays introduced in online calculation of the TKED are considered for the actual analysis of transient stability. Global positioning system (GPS) is proposed for the practical implementation of the calculation of the TKED. Simulation results of balanced fault at different points in a multi-machine power system show that the proposed fuzzy logic-controlled SMES is an effective device for transient stability enhancement of multi-machine power system. Moreover, the transient stability performance is effected by the communication delay.     

SMES用电压源型功率调节系统的建模与控制方法研究

以电压源型功率调节系统为对象,研究其建模及其控制方法。首先给出电压源型功率调节系统的结构,包括电压源型变流器和斩波器的主电路拓扑结构及其连接关系;随后导出占空比表达的PCS低频数学模型,并使用非线性变换实现状态方程线性化,基于线性化后的模型给出有功功率、无功功率及直流电压解耦的控制系统设计方法;最后在Matlab/Simulink环境下对PCS功率跟踪能力及SMES装置抑制风电功率波动的效果进行了仿真验证。仿真结果表明：所设计的PCS系统控制器对阶跃和正弦规律变化的功率指令具有优秀的跟踪能力,同时具有较强稳定直流电压的能力,该PCS接口的超导储能装置应用于风力发电系统中,能够达到减小风电功率波动,平息出力的目标。     

大储能容量超导磁储能系统的拓扑结构及控制策略

随着可再生能源规模化发展,电网对大功率等级储能系统的需求日益增长,因此研究应用于大功率等级场合的超导磁储能(SMES)系统拓扑结构及运行控制策略具有重要的理论意义.提出了一种基于模块化多电平换流器(MMC)的SMES系统拓扑结构,设计了允许多个超导磁体同时接入以成倍数提升系统整体储能容量的新型斩波器.该新型斩波器采用模块化设计,由多个子模块串联构成,可随MMC扩展至多种电压等级和功率等级,且能够均衡各子模块的电容电压和磁体电流.针对新型斩波器的旁路子模块数量难以确定的问题,提出了新型斩波器旁路子模块数量的计算方法.基于线性自抗扰控制设计了MMC双闭环控制器和新型斩波器的直流电压控制器,利用复频域分析法整定了线性自抗扰控制器参数.通过仿真验证了所提拓扑结构和控制策略的正确性和有效性.     

基于输入/输出反馈线性化的SMES控制策略研究

由于超导磁储能系统(SMES)的非线性特性,精准的控制策略是SMES实际应用的基础。文中提出了一种基于新型非线性鲁棒控制的SMES功率控制策略。建立了电压源型SMES的交流侧变流器以及直流斩波器两部分的数学模型。根据反馈线性化原理,设计了SMES基于输入/输出反馈线性化控制策略。仿真结果表明,基于输入/输出反馈线性化控制的SMES对功率指令具有优秀的跟踪能力,同时能够快速稳定直流侧电压。与SMES的经典PI控制策略进行对比分析,所提出的控制策略具有更好的鲁棒性和快速收敛性。     

超导磁储能系统自抗扰控制策略研究

本文针对电压源型换流器(voltage source converter, VSC)的超导磁储能(superconducting magnetic energy storage, SMES)系统,设计了一款自抗扰控制(active disturbance rejection control, ADRC)。首先,分别建立了SMES的交流侧VSC、直流侧斩波器数学模型;其次,基于非线性扩张状态观测器和线性误差反馈律设计了SMES的交、直流侧ADRC;然后,通过描述函数法分析了ADRC的稳定性;最后,在MATLAB/Simulink平台中搭建了仿真模型。仿真结果表明,与传统PI控制相比,ADRC具有更好的动态响应性能和抗扰动特性,并针对系统参数的不确定性具有更好的鲁棒性,有效地提高了SMES的运行可靠性。     

基于超导储能装置的配电网谐波与电压凹陷补偿技术

针对非线性冲击负载引起的电压凹陷大、电网谐波比重大和功率因数低等电能质量问题,提出了一种基于超导储能技术的三相电压源型变流器(voltage source converter,VSC)反馈伪线性化控制方法。在三相VSC数学模型中使用逆系统,达到直流电容、电压和无功电流的完全解耦,并构造出伪线性系统。设计了斩波器的电流调节控制系统,充分发挥了超导储能的续流能力。设计了内电流环控制器,解决了诸多电能质量问题,并对VSC容量进行最优整定。     

Improvement of Wind-Generator Stability by Fuzzy-Logic-Controlled SMES

This paper proposes a fuzzy-logic-controlled superconducting magnetic energy storage (SMES) scheme for the stabilization of grid-connected wind-generator systems. The control scheme of SMES is based on a sinusoidal pulsewidth-modulation voltage-source converter and a two-quadrant dc–dc chopper using an insulated-gate bipolar transistor. A comparative study is carried out between the proposed fuzzy-logic-controlled SMES and the fuzzy-logic-based pitch controller to improve the wind-generator stability. Simulation results demonstrate that the performance of the proposed fuzzy-logic-controlled SMES is better than that of the fuzzy-logic-based pitch controller in order to stabilize the wind generator.      

基于无源控制理论的准Z源超导磁储能系统

超导磁储能(superconductivity magnetic energy storage,SMES)系统通过变流器来实现电网与超导磁体的功率交换。但传统的储能变流器存在输出电压范围有限以及桥臂上下开关易受干扰造成直通而损坏的问题。为实现超导磁储能系统的安全稳定运行,提出了基于双向准Z源变流器(quasi-Z source converter,QZSC)的超导磁储能系统,并针对QZSC-SMES系统的非线性、强耦合特点,在QZSC-SMES系统的交流侧变流器和直流侧斩波器采用基于欧拉?拉格朗日(Euler-Lagrange,E-L)模型的无源控制策略。仿真结果验证了所提QZSC-SMES拓扑及其控制策略的有效性:系统可以快速准确跟踪有功无功指令,相比传统PI控制,系统具有更低的并网谐波含量、更好的动态性能和更强的鲁棒性。     

用超导电力磁储能系统改善发电机的阻尼

对电力系统中超导磁储能(SEMS)装置的关键技术——电力电子电路的拓扑结构进行了比较，对电压源型SMES尤其是关键的功率调节系统(PCS)进行了详细的分析，并在电力系统动态模拟平台上进行了试验，给出了一些模拟试验结果。     

On-line monitoring of eigen-frequency and stability of power system by use of SMES

It is useful to grasp power system stability margin from on-line data in real time. We have proposed to estimate the system operating conditions from on-line data by use of superconducting magnetic energy storage (SMES) system. In this paper, we developed the proposed method to monitor the eigen-frequency of the power system in real time, which changes with time due to the system operating conditions (such as, generator output change), by use of a SMES and a lock-in amplifier. Basic experiments were carried out on an analogue-type power system simulator and a model SMES for the simulator. By use of the SMES, the eigen-frequency change according to the operating condition change was successfully measured, tracked and monitored on-line. The stability margin can be estimated by the monitored eigen-frequency. The availability of the proposed method is discussed on the experimental results.     

A fuzzy logic‐controlled SMES for damping shaft torsional oscillations of synchronous generator

This paper presents a fuzzy logic control scheme for the superconducting magnetic energy storage (SMES) based on a PWM voltage source converter and a two‐quadrant chopper using an insulated‐gate‐bipolar‐transistor (IGBT) to dampen turbine‐generator shaft torsional oscillations. Simulation results of balanced faults in a single machine connected to an infinite bus system show that the proposed fuzzy logic‐controlled SMES is effective in damping shaft torsional oscillations of synchronous generators (GENs). © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

StatCom-SMES

This article presents the modeling and control of the integration of a StatCom (static-synchronous compensator) with SMES (superconducting magnetic energy storage system) and its dynamic response to system oscillations caused by a three-phase fault. It has been shown that the StatCom-SMES combination can be very effective in damping power system oscillations. Adding energy storage enhances the performance of a StatCom and possibly reduces the MVA ratings requirements of the StatCom operating alone. This is important for a cost/benefit analysis of installing flexible AC transmission system controllers on utility systems. It should be noted that, in this study, the StatCom provides a real power flow path for SMES, but the SMES controller is independent of the StatCom controller. While the StatCom is ordered to absorb or inject reactive power, the SMES is ordered to absorb/inject real power. It was also observed that the location where the combined compensator is connected is important for improvement of overall system dynamic performance. Although the use of a reactive power controller seems more effective in a load area, this simulation study shows that a StatCom with real power capability can damp the power system oscillations more effectively, thereby stabilizing the system faster-if the StatCom-SMES controller is located near a generation area rather than a load area.     

Application of superconducting magnet energy storage to improvepower system dynamic performance

The application of superconducting magnet energy storage (SMES) to the stabilization of a power system with long-distance bulk power transmission lines which has the problem of poorly damped power oscillations is presented. Control schemes for stabilization using SMES capable of controlling active and reactive power simultaneously in four quadrant ranges are proposed. The effective locations and the necessary capacities of SMES for power-system-stabilizing control are discussed in detail. Results of numerical analysis and experiments in an artificial power-transmission system demonstrate the significant effect of the control by SMES on the improvement of power-system oscillatory performance     

超导电力磁储能系统研究进展(一)——超导储能装置

介绍了超导磁储能装置（SMES）的基本原理、系统组成和发展状况,阐述了具有高效、快速响应、能与系统独立进行四象限交换有功和无功功率等特性的SMES在电力系统中应用的重要意义,概述了SMES的应用前景和需要进一步解决的若干问题,并针对我国SMES研究的现状提出了一些建设性意见。