为改善并网点电压稳定性和降低换相失败率,基于电网换相换流器的高压直流输电(line commutated converter-based high voltage direct current,LCC-HVDC)系统采用静止同步补偿器(static synchronous compensator,STATCOM)对换流站进行...为改善并网点电压稳定性和降低换相失败率,基于电网换相换流器的高压直流输电(line commutated converter-based high voltage direct current,LCC-HVDC)系统采用静止同步补偿器(static synchronous compensator,STATCOM)对换流站进行无功补偿,但随着新能源的大规模接入,电网强度逐渐弱化,弱电网环境下含STATCOM的LCC-HVDC换流站系统稳定性问题也日益突出。文中针对弱电网下含STATCOM的LCC-HVDC换流站,提出一种基于导纳降幅和相位补偿协同的稳定性提高方法。首先,通过小信号方法建立换流站在dq坐标系下的导纳模型;进而,根据LCC和STATCOM导纳模型的特点,提出换流站稳定性提升方法,即通过将导纳重塑因子引入LCC的控制环节,减小其导纳幅值,使系统的回比矩阵特征值轨迹更难包围(-1,0)点,并通过STATCOM的相位补偿进一步消除导纳元素负阻尼区间,为系统提供正阻尼,从而增强系统稳定性;最后,通过Matlab/Simulink和RT-LAB实验平台对重塑方法进行验证,证明方案的有效性。展开更多
Voltage instability and reactive power fluctuations represent major challenges for DFIG-based wind turbines under load variations and grid disturbances.This paper proposes an integrated fault ride-through enhancement ...Voltage instability and reactive power fluctuations represent major challenges for DFIG-based wind turbines under load variations and grid disturbances.This paper proposes an integrated fault ride-through enhancement scheme based on a STATCOM supported by a Battery Energy Storage System(BESS)and a braking chopper(BC).The STATCOM regulates the DFIG terminal voltage through dynamic reactive power compensation using a coordinated outer voltage loop and inner synchronous dq-axis current control.The BESS supports the STATCOM DC side and enables fast bidirectional power exchange,while the BC suppresses overvoltage in the DFIG back-to-back converter DClink during fault conditions.The proposed DFIG protection scheme is modeled and evaluated in MATLAB/Simulink under step load changes and severe voltage sag and swell conditions.The results demonstrate that the proposed scheme maintains the DFIG terminal voltage at its rated value during load variations,restores it from 0.05 to 0.97 p.u.under severe voltage sag,and regulates it to 1.O p.u.under severe voltage swell.In addition,DC-link voltage excursions are significantly reduced under severe disturbances.These findings confirm the effectiveness of the proposed strategy in enhancing fault ride-through capability and improving the dynamic stability of DFIG-based wind turbines.展开更多
This work presents a fuzzy based methodology for distribution system feeder reconfiguration considering DSTATCOM with an objective of minimizing real power loss and operating cost. Installation costs of DSTATCOM devic...This work presents a fuzzy based methodology for distribution system feeder reconfiguration considering DSTATCOM with an objective of minimizing real power loss and operating cost. Installation costs of DSTATCOM devices and the cost of system operation, namely, energy loss cost due to both reconfiguration and DSTATCOM placement, are combined to form the objective function to be minimized. The distribution system tie switches, DSTATCOM location and size have been optimally determined to obtain an appropriate operational condition. In the proposed approach, the fuzzy membership function of loss sensitivity is used for the selection of weak nodes in the power system for the placement of DSTATCOM and the optimal parameter settings of the DFACTS device along with optimal selection of tie switches in reconfiguration process are governed by genetic algorithm(GA). Simulation results on IEEE 33-bus and IEEE 69-bus test systems concluded that the combinatorial method using DSTATCOM and reconfiguration is preferable to reduce power losses to 34.44% for 33-bus system and to 45.43% for 69-bus system.展开更多
基于模块化多电平换流器的静止同步补偿器(stationary synchronous compensator based on modular multilevel converters,MMC-STATCOM)是高压电力系统中无功补偿的关键设备,其传统线性控制器性能会因运行点的大范围变化而恶化。针对该...基于模块化多电平换流器的静止同步补偿器(stationary synchronous compensator based on modular multilevel converters,MMC-STATCOM)是高压电力系统中无功补偿的关键设备,其传统线性控制器性能会因运行点的大范围变化而恶化。针对该问题,该文提出了一种基于滑模状态反馈精确线性化的非线性智能控制策略,首先通过选择合适的输出函数、坐标变换,将不做任何简化的3阶MMC-STATCOM非线性模型转化为一个可控的Brunovsky标准型线性系统,并通过数学理论证明了该模型满足精确线性化条件。然后采用改进的粒子群算法配置其反馈增益矩阵,利用积分滑模控制计算其平衡点。最后通过状态反馈使各个状态变量快速收敛至平衡点。将该控制策略与传统PI控制、LQR状态反馈控制通过硬件在环实时仿真平台进行对比实验,结果表明该控制策略具有更好的动态特性、暂态稳定性、鲁棒性,尤其适用于运行环境发生大扰动时。此外,该控制策略的设计过程可以拓展应用于其他类型的柔性交流输电装置。展开更多
摘要为改善并网点电压稳定性和降低换相失败率,基于电网换相换流器的高压直流输电(line commutated converter-based high voltage direct current,LCC-HVDC)系统采用静止同步补偿器(static synchronous compensator,STATCOM)对换流站进行无功补偿,但随着新能源的大规模接入,电网强度逐渐弱化,弱电网环境下含STATCOM的LCC-HVDC换流站系统稳定性问题也日益突出。文中针对弱电网下含STATCOM的LCC-HVDC换流站,提出一种基于导纳降幅和相位补偿协同的稳定性提高方法。首先,通过小信号方法建立换流站在dq坐标系下的导纳模型;进而,根据LCC和STATCOM导纳模型的特点,提出换流站稳定性提升方法,即通过将导纳重塑因子引入LCC的控制环节,减小其导纳幅值,使系统的回比矩阵特征值轨迹更难包围(-1,0)点,并通过STATCOM的相位补偿进一步消除导纳元素负阻尼区间,为系统提供正阻尼,从而增强系统稳定性;最后,通过Matlab/Simulink和RT-LAB实验平台对重塑方法进行验证,证明方案的有效性。
基金supported and funded by theDeanship of Scientific Research at ImamMohammad Ibn Saud Islamic University(IMSIU)(grant number IMSIU-DDRSP2603).
摘要Voltage instability and reactive power fluctuations represent major challenges for DFIG-based wind turbines under load variations and grid disturbances.This paper proposes an integrated fault ride-through enhancement scheme based on a STATCOM supported by a Battery Energy Storage System(BESS)and a braking chopper(BC).The STATCOM regulates the DFIG terminal voltage through dynamic reactive power compensation using a coordinated outer voltage loop and inner synchronous dq-axis current control.The BESS supports the STATCOM DC side and enables fast bidirectional power exchange,while the BC suppresses overvoltage in the DFIG back-to-back converter DClink during fault conditions.The proposed DFIG protection scheme is modeled and evaluated in MATLAB/Simulink under step load changes and severe voltage sag and swell conditions.The results demonstrate that the proposed scheme maintains the DFIG terminal voltage at its rated value during load variations,restores it from 0.05 to 0.97 p.u.under severe voltage sag,and regulates it to 1.O p.u.under severe voltage swell.In addition,DC-link voltage excursions are significantly reduced under severe disturbances.These findings confirm the effectiveness of the proposed strategy in enhancing fault ride-through capability and improving the dynamic stability of DFIG-based wind turbines.
基金supported by Borujerd Branch,Islamic Azad University Iran
摘要This work presents a fuzzy based methodology for distribution system feeder reconfiguration considering DSTATCOM with an objective of minimizing real power loss and operating cost. Installation costs of DSTATCOM devices and the cost of system operation, namely, energy loss cost due to both reconfiguration and DSTATCOM placement, are combined to form the objective function to be minimized. The distribution system tie switches, DSTATCOM location and size have been optimally determined to obtain an appropriate operational condition. In the proposed approach, the fuzzy membership function of loss sensitivity is used for the selection of weak nodes in the power system for the placement of DSTATCOM and the optimal parameter settings of the DFACTS device along with optimal selection of tie switches in reconfiguration process are governed by genetic algorithm(GA). Simulation results on IEEE 33-bus and IEEE 69-bus test systems concluded that the combinatorial method using DSTATCOM and reconfiguration is preferable to reduce power losses to 34.44% for 33-bus system and to 45.43% for 69-bus system.
摘要基于模块化多电平换流器的静止同步补偿器(stationary synchronous compensator based on modular multilevel converters,MMC-STATCOM)是高压电力系统中无功补偿的关键设备,其传统线性控制器性能会因运行点的大范围变化而恶化。针对该问题,该文提出了一种基于滑模状态反馈精确线性化的非线性智能控制策略,首先通过选择合适的输出函数、坐标变换,将不做任何简化的3阶MMC-STATCOM非线性模型转化为一个可控的Brunovsky标准型线性系统,并通过数学理论证明了该模型满足精确线性化条件。然后采用改进的粒子群算法配置其反馈增益矩阵,利用积分滑模控制计算其平衡点。最后通过状态反馈使各个状态变量快速收敛至平衡点。将该控制策略与传统PI控制、LQR状态反馈控制通过硬件在环实时仿真平台进行对比实验,结果表明该控制策略具有更好的动态特性、暂态稳定性、鲁棒性,尤其适用于运行环境发生大扰动时。此外,该控制策略的设计过程可以拓展应用于其他类型的柔性交流输电装置。