基于Crowbar保护电路的双馈风电系统高电压穿越

针对电网电压发生骤升故障时造成的电网不稳定运行,在双馈机组转子侧加入Crowbar保护电路,增加双馈风电系统高电压穿越的能力。通过建立电网电压骤升时双馈风电机组投入Crowbar保护电路后的数学模型,并从磁链角度推导出转子侧暂态电流及其最大估算值,根据短路电流和直流侧母线耐受电压的大小,确定Crowbar电路串联的电阻值、切入和退出时间,加速系统暂态电流的衰减,实现双馈系统的高电压穿越。Matlab/Simulink仿真结果表明:控制方案增强了双馈发电系统稳定运行的可靠性,并提高了双馈风力发电系统的高电压穿越能力。     

双馈风电机组低电压穿越特性的试验研究

低电压穿越能力正逐渐成为大型并网风电机组的必备功能之一,要求风电机组在电网电压跌落发生时保持并网,故障消除后快速恢复正常运行。在分析双馈机组电压跌落特性的基础上,采用了转子主动式Crowbar电路和直流侧卸荷电路相结合的方法来实现双馈风电机组的低电压穿越功能,讨论了具体的低电压穿越控制策略,通过仿真验证了电路结构和控制策略的正确性。在实验室10 kW双馈机组实验平台上,采用电压跌落发生器模拟电网电压跌落故障,进行了电网电压跌落至额定电压20%时不同持续时间的测试,证实了所采用的低电压穿越控制策略的有效性。     

双馈异步风力发电系统电网故障穿越能力研究

在分析风电机组并网导则的基础上,首先对双馈异步风力发电机组进行数学模型的建立,分析了电网对称运行情况下的控制策略.然后对电机在电网电压跌落情况下的运行状况作理论分析,并提出采用主动式Crowbar电路来保护转子侧变流器和发电机本身的方案.在MATLAB/Simulink建立的风电场模型中进行电网电压深度跌落情况下的仿真...     

基于撬棒保护电路的双馈风电机组的无功协调控制方法研究

电网故障下撬棒(Crowbar)保护电路能够帮助风电机组实现低电压穿越,为转子故障电流提供旁路并限制其幅值。在Crowbar保护电路退出运行时,风电机组需要吸收大量的无功功率,这大大影响了风电系统恢复稳定运行的能力。针对以上问题,根据Crowbar保护电路的动作情况,提出了一种利用双馈风机网侧变换器进行无功补偿的控制策略,并进行了仿真分析。仿真结果表明,通过双馈风机网侧变换器为电网提供无功支持,Crowbar保护电路退出时刻吸收的无功功率明显减小,增强了系统恢复稳定运行的能力。     

兆瓦级双馈风电机组电网故障时的暂态分析

以1.5MW双馈式风力发电机组为研究对象,通过分析双馈式异步发电机的暂态电气关系,给出了电网三相短路故障时双馈式异步电机的定子绕组暂态电流和转子绕组暂态电流的计算方法.建立双馈式风电机组的并网模型,并进行了电网三相短路故障的仿真,仿真结果验证了暂态响应算法的有效性.对双馈式风电机组的Crowbar电路的作用进行了理论分析和仿真研究,采用Crowbar电路时风电机组的暂态响应比未采用该电路时有了明显改善.     

兆瓦级双馈风电机组电网故障时的暂态分析

以1.5MW双馈式风力发电机组为研究对象,通过分析双馈式异步发电机的暂态电气关系,给出了电网三相短路故障时双馈式异步电机的定子绕组暂态电流和转子绕组暂态电流的计算方法。建立双馈式风电机组的并网模型,并进行了电网三相短路故障的仿真,仿真结果验证了暂态响应算法的有效性。对双馈式风电机组的Crowbar电路的作用进行了理论分析和仿真研究,采用Crowbar电路时风电机组的暂态响应比未采用该电路时有了明显改善。     

UPFC提高双馈风电机组稳定性的动态仿真分析

提高风电场的低电压穿越能力LVRT（Low Voltage Ride Through）以及维持并网系统暂态稳定具有重大意义。针对双馈风电机组利用自身背靠背变流器控制电磁转矩和无功功率这一方案的不足以及撬棒保护电路（Crowbar）在故障期间频繁投入与退出可能引起电磁转矩波动的问题。分析了UPFC和双馈风电机组的数学模型与控制策略,在DIgSILENT/PowerFactory中建立了含UPFC的风电并网系统仿真模型,通过研究故障前后风电场PCC节点电压,风电场发出功率状况以及风电机组的转速稳定性,验证了UPFC对风电场电压稳定的支撑作用,并能维持风电并网系统的暂态稳定。     

基于主动式IGBT型Crowbar的双馈风力发电系统LVRT仿真研究

讨论了电网电压骤降下双馈感应风电（DFIG）系统的低压穿越控制策略和保护方案。在分析主动式IGBT型Crowbar电路的拓扑结构以及电网电压跌落时Crowbar电路作用的基础上,采用计及电网电压变化的DFIG数学模型,建立了LVRT控制模型。通过仿真详细研究了Crowbar投切策略,仿真结果验证了Crowbar电路以及控制策略的有效性,表明Crowbar电路能有效抑制转子过电流、直流母线过电压以及电磁转矩的振荡,并可在故障时向电网注入无功电流以帮助电网电压的恢复,使DFIG实现低电压穿越。     

双馈风电机组零电压穿越能力测试方案

为测试双馈风电机组的零电压穿越能力,取得行业认可的检测报告,以在运行的某2MW双馈风电机组为例,开展了基于澳大利亚电网标准的零电压穿越能力测试。通过对不同电压跌落故障期间转子电流(电压)的理论分析,明确了机组控制策略及硬件设备的技术改造方向,结合预测试结果,仿真计算了Crowbar组件过流能力和Crowbar电阻阻值,优化了Crowbar电路的部分设计,最终选定了可通过测试的技术改造方案,为双馈风电机组优化运行和技术革新提供了理论指导,也为优化其并网能力提供了借鉴。     

基于主动式IGBT型Crowbar的双馈风力发电系统LVRT仿真研究

讨论了电网电压骤降下双馈感应风电(DFIG)系统的低压穿越控制策略和保护方案.在分析主动式IGBT型Crowbar电路的拓扑结构以及电网电压跌落时Crowbar电路作用的基础上,采用计及电网电压变化的DFIG数学模型,建立了LVRT控制模型.通过仿真详细研究了Crowbar投切策略,仿真结果验证了Crowbar电路以及控制策略的有效性,表明Crowbar电路能有效抑制转子过电流、直流母线过电压以及电磁转矩的振荡,并可在故障时向电网注入无功电流以帮助电网电压的恢复,使DFIG实现低电压穿越.     

基于PSCAD的2MW双馈风力发电机组低电压穿越能力研究

随着以变速恒频双馈异步发电机为主体的大型风力发电机组在电网中所占比例的迅速提高,电力系统对并网风机在外部电网故障,特别是电网电压跌落下的不间断运行能力提出了更高的要求。首先介绍了德国EON风力发电系统低电压穿越标准,在定子磁链定向的基础上推导了双馈风力发电系统的有功无功解耦控制策略,最后在PSCAD中建立了具有Crowbar保护电路的2 MW双馈风力发电系统模型。仿真结果表明双馈风力发电系统具有很好的电压风穿越能力,正常运行状态下能够实现单位功率因素运行。     

基于Crowbar电路的双馈感应风力发电系统低电压穿越的仿真分析

在分析变速恒频双馈风力发电机组和Crowbar电路工作原理的基础上,建立双馈风力发电系统低电压穿越(LVRT)控制模型和Crowbar控制策略。在PSCAD/EMTDC仿真软件中搭建了双馈感应发电机(DFIG)系统模型和LVRT控制模型。针对电网三相对称短路故障下Crowbar的投切策略进行了仿真研究。仿真结果验证,所提策略能实现双馈风力发电机的低电压穿越。     

IGBT型Crowbar保护电路仿真研究

采用Crowbar保护电路可以极大地提高双馈式风电系统的低电压穿越能力(LVRT)。建立了双馈风力发电机(DFIG)的数学模型,对IGBT型Crowbar保护电路关键参数—卸能电阻最优值范围进行研究。并通过MATLAB/Simulink搭建了变速恒频DFIG风力发电系统模型,仿真表明当电网电压大幅度跌落时采取Crowbar保护电路的必要性。     

A Dynamic Reactive Power Control for DFIG Wind Turbines andIts Impacts on Distribution Protections

With the increasing penetration of distributed generations(DGs)into power grids,the fault ride-through ability of DG is attracting more and more attention.Recent grid codes require a DG to maintain its connection with the grid during grid faults and to play an active role in the recovery of grid voltage.This paper chooses the doublyfed induction generator(DFIG)as the typical wind turbine for study.Firstly,a dynamic reactive power control strategy is proposed to improve the fault ride-through characteristic of a DFIG.The contributions of a DFIG to the fault current under the dynamic reactive power control and the Crowbar control are analyzed and compared based on the mathematical expressions and control behaviors.The impacts of a DFIG under two control strategies on distribution protections are discussed.Studies show that although a DFIG under the dynamic reactive power control provides more fault current component than one under the Crowbar control,its impacts on distribution protections are acceptable.Finally,a 10kV distribution network with a DFIG is simulated in PowerFactory DIgSILENT.The simulation results prove the correctness of above theoretical analysis.     

利用改进Crowbar电路提高DFIG低电压穿越能力

在分析传统Crowbar保护电路的基础上,提出利用串联制动电阻的改进Crowbar保护电路.利用MATLAB/Simulink仿真平台建立了基于双馈感应风力发电机(DFIG)的风电场并网仿真模型,针对提出的改进保护电路,对双馈感应风力发电机在电网电压跌落的情况下的运行特性进行了仿真研究,并将两种电路的保护效果进行对比,结果表明,该改进保护电路设计合理,有效地提高了DFIG的低电压穿越能力.     

Crowbar保护在双馈异步风力发电系统电网故障穿越中的应用

随着风电装机容量的增大,对风电机组并网的低电压穿越能力提出了更高的要求.在分析现行风电机组并网导则的基础上,对双馈异步风力发电机组在电网电压跌落情况下的运行状况进行理论分析,提出采用Crowbar电路来保护转子励磁电源和发电机自身的方案.在Matlab/Simulink建立的风电场模型中进行仿真以验证其有效性.仿真结果...     

基于组合保护方案提高DFIG低电压穿越能力的仿真分析

电网故障导致电压跌落时,大容量风电场中风机的相继切出会影响系统运行的稳定性。为保证电网安全可靠运行,风力发电机组的并网导则要求目前广泛应用的双馈感应发电机（DFIG）具备低电压穿越（LVRT）能力,即确保电网电压跌落情况下DFIG保持不脱网运行。本文在深入分析传统Crowbar保护电路的基础上,针对其不足提出了组合保护方案并给出了相应的控制策略。基于Matlab/Simulink平台建立了风电场并网运行仿真模型,仿真结果表明所提组合保护方案能够有效提高DFIG的低电压穿越能力。     

Short circuit fault analysis in a grid connected DFIG based wind energy system with active crowbar protection circuit for ridethrough capability and power quality improvement

In power industry, improvement of the short circuit Fault-ride through (FRT) capability of grid integrated Doubly Fed Induction Generators (DFIGs) for the wind power system is an important issue. In this paper an Active Crowbar Protection (ACB_P) system is proposed to enhance the Fault-ride through (FRT) capability of DFIG so as to improve the power quality of the system. The protection scheme proposed here is designed with a capacitor in series with the resistor unlike the conventional Crowbar (CB) having only resistors. The importance of ACB_P is to maintain the connection of DFIG with the grid during fault conditions to provide uninterruptable power supply to the loads. The major functions of the capacitor in the protection circuit are to eliminate the ripples generated in the rotor current and to protect the converters as well as the DC-link capacitor. The main objectives of the proposed approach are: minimisation of magnitude of rotor fault currents, maintenance of constant DC-link voltage, reduction in crowbar operation time to avoid disconnection between the DFIG and the Rotor side converter (RSC), improvement in the short circuit response of terminal voltage and enhancement in the dynamic responses of the DFIG. These objectives are achieved through the incorporation of ACB_P scheme between the rotor of the DFIG and RSC. The proposed scheme is validated on different types of fault conditions and it is observed that there is significant improvement in the objectives. Simulation results are carried out on a 1.7 MVA DFIG based WECS under different types of short circuit faults in MATLAB/Simulation and functionality of the proposed scheme is verified.     

应对电网电压骤降的双馈感应风力发电机Crowbar控制策略

双馈感应发电机(doubly fed induction generator,DFIG)具有有功、无功功率独立调节的能力及励磁变频器所需容量小等优点,在风力发电系统中得到了广泛应用,但由于励磁变频器的容量较小,使其在电网故障下的控制能力受到限制。为保护励磁变频器,需要采用Crowbar装置在电压骤降时为转子浪涌电流提供通路,并限制转子电流增大。文章提出了一种Crowbar控制策略,能有效抑制转子过电流、直流母线过电压以及电磁转矩的振荡,并可向电网注入无功电流以帮助电网电压的恢复。仿真结果验证了这种控制方式能使DFIG在大幅电压骤降故障下实现不间断运行,有效提高了DFIG风电机组运行的可靠性。     

A novel controllable crowbar based onfault type protection technique for DFIGwind energy conversion system usingadaptive neuro-fuzzy inference system

This paper proposes a novel controllable crowbar based on fault type (CBFT) protection technique for doubly fed induction generator (DFIG) wind energy conversion system connected to grid. The studied system consists of six DFIG wind turbines with a capacity of 1.5 MW for each of them. The operation mechanism of proposed technique is used to connect a set of crowbar resistors in different connection ways via activation of controllable circuit breakers (CBs) depending on the detected fault type. For each phase of DFIG, a crowbar resistor is connected in parallel with a controllable CB and all of them are connected in series to grid terminals. The adaptive neuro-fuzzy inference system (ANFIS) networks are designed to detect the fault occurrence, classify the fault type, activate the CBs for crowbar resistors associated with faulted phases during fault period, and deactivate them after fault clearance. The effectiveness of proposed CBFT protection technique is investigated for different fault types such as symmetrical and unsymmetrical faults taking into account the single-phase to ground fault is the most frequently fault type that occurs in power systems. Also, a comparison between the behaviours of studied system in cases of using traditional parallel rotor crowbar, classical outer crowbar, and proposed CBFT protection techniques is studied. The fluctuations of DC-link voltage, active power, and reactive power for studied system equipped with different protection techniques are investigated. Moreover, the impacts of different crowbar resistance values on the accuracy of proposed technique are studied. The simulation results show that, the proposed technique enhances the stability of studied wind turbine generators and contributes in protection of their components during faults.