An input-output signal selection based on Phillips-Heffron model of a parallel high voltage alternative current/high voltage direct current(HVAC/HVDC) power system is presented to study power system stability. It is w...An input-output signal selection based on Phillips-Heffron model of a parallel high voltage alternative current/high voltage direct current(HVAC/HVDC) power system is presented to study power system stability. It is well known that appropriate coupling of inputs-outputs signals in the multivariable HVDC-HVAC system can improve the performance of designed supplemetary controller. In this work, different analysis techniques are used to measure controllability and observability of electromechanical oscillation mode. Also inputs–outputs interactions are considered and suggestions are drawn to select the best signal pair through the system inputs-outputs. In addition, a supplementary online adaptive controller for nonlinear HVDC to damp low frequency oscillations in a weakly connected system is proposed. The results obtained using MATLAB software show that the best output-input for damping controller design is rotor speed deviation as out put and phase angle of rectifier as in put. Also response of system equipped with adaptive damping controller based on HVDC system has appropriate performance when it is faced with faults and disturbance.展开更多
Wind energy sources have different structures and functions from conventional power plants in the power system.These resources can affect the exchange of active and reactive power of the network.Therefore,power system...Wind energy sources have different structures and functions from conventional power plants in the power system.These resources can affect the exchange of active and reactive power of the network.Therefore,power system stability will be affected by the performance of wind power plants,especially in the event of a fault.In this paper,the improvement of the dynamic stability in power system equipped by wind farm is examined through the supplementary controller design in the high voltage direct current(HVDC)based on voltage source converter(VSC)transmission system.In this regard,impacts of the VSC HVDC system and wind farm on the improvement of system stability are considered.Also,an algorithm based on controllability(observability)concept is proposed to select most appropriate and effective coupling between inputs-outputs(IO)signals of system in different work conditions.The selected coupling is used to apply damping controller signal.Finally,a fractional order PID controller(FO-PID)based on exchange market algorithm(EMA)is designed as damping controller.The analysis of the results shows that the wind farm does not directly contribute to the improvement of the dynamic stability of power system.However,it can increase the controllability of the oscillatory mode and improve the performance of the supplementary controller.展开更多
Variable speed pumped storage machines are used extensively in wind power plant and pumped storage power plant. This paper presents direct torque and flux control(DTFC) of a variable speed pumped storage power plant(V...Variable speed pumped storage machines are used extensively in wind power plant and pumped storage power plant. This paper presents direct torque and flux control(DTFC) of a variable speed pumped storage power plant(VSPSP). By this method both torque and flux have been applied to control the VSPSP. The comparison between VSPSP's control strategies is studied. At the first, a wind turbine with the capacity 2.2 k W and DTFC control strategies simulated then a 250 MW VSPSP is simulated with all of its parts(including electrical, mechanical, hydraulic and its control system) by MATLAB software. In all of simulations, both converters including two-level voltage source converter(2LVSC) and three-level voltage source converter(3LVSC) are applied. The results of applying 2LVSC and 3LVSC are the rapid dynamic responses with better efficiency, reducing the total harmonic distortion(THD) and ripple of rotor torque and flux.展开更多
从实际工程应用出发,建立了单塔双循环湿式烟气脱硫(Single-tower and double-circulation wet flue gas desulfurization,SD-WFGD)系统的控制系统。首先,利用历史运行数据,考虑SD-WFGD系统运行过程吸收塔变频浆液循环泵在不同浆液pH时...从实际工程应用出发,建立了单塔双循环湿式烟气脱硫(Single-tower and double-circulation wet flue gas desulfurization,SD-WFGD)系统的控制系统。首先,利用历史运行数据,考虑SD-WFGD系统运行过程吸收塔变频浆液循环泵在不同浆液pH时单位频率变化对烟气SO_(2)浓度的影响,建立了系统动态模型。然后,基于浆液pH脱硫能力提出了直接硫量平衡控制(Direct sulfur balance control,DSC)策略,将已建立的动态模型作为控制模型,并利用传统PID控制器结合DSC策略,建立了SD-WFGD系统串联控制系统。仿真实验结果表明:与传统的PID控制方案相比,所提优化控制方案减小了供浆流量和出口SO_(2)浓度的波动,能够大幅度提升SD-WFGD系统的控制性能,从而更好地保证脱硫系统在燃煤电站灵活运行的背景下安全、稳定、经济及灵活运行。展开更多
针对直驱式永磁同步风力发电系统风速多变、非线性和强扰动的问题,提出一种基于模糊控制和线性自抗干扰控制(Linear Active Disturbance Retection Control,LADRC)的混合控制方法。首先对线性自抗扰中的扩张状态观测器(Linear Extended ...针对直驱式永磁同步风力发电系统风速多变、非线性和强扰动的问题,提出一种基于模糊控制和线性自抗干扰控制(Linear Active Disturbance Retection Control,LADRC)的混合控制方法。首先对线性自抗扰中的扩张状态观测器(Linear Extended State Observer,LESO)进行改进,提高对扰动观测的能力,同时利用模糊控制动态调整LADRC控制参数,增强系统的抗干扰能力和鲁棒性。仿真结果表明,与传统PI控制器相比,该方法能够更好地估计风速引起的转矩波动,准确跟踪额定转速,实现风能利用最大化。展开更多
传统双向E型无线电能传输(wireless power transfer,WPT)拓扑易进入硬开关状态,导致电能传输效率低。针对此,该文提出无线电能传输系统的改进E^(#)型拓扑及其移相控制策略。首先,构建软开关状态负载范围更宽的双向E^(#)型WPT电路拓扑数...传统双向E型无线电能传输(wireless power transfer,WPT)拓扑易进入硬开关状态,导致电能传输效率低。针对此,该文提出无线电能传输系统的改进E^(#)型拓扑及其移相控制策略。首先,构建软开关状态负载范围更宽的双向E^(#)型WPT电路拓扑数学模型,分析并提取电路实现软开关工作状态的关键变量与约束条件,理论上证明所提拓扑的有效性。然后,推导电路中线圈互感和负载阻抗等参数的解析关系式,并基于此提出可保证系统在负载时始终处于最佳工作状态的移相控制策略。该策略通过控制开关管的门极驱动信号相位,使谐振元件内部储存的能量提前或者滞后释放,从而将开关管修正回软开关状态。最后,通过仿真和实验验证所提双向E^(#)型WPT系统的有效性。实验结果表明,所提方法可保证在5~30Ω的负载范围内电路工作在软开关状态,该范围内的电能传输效率峰值达84.3%。展开更多
文摘An input-output signal selection based on Phillips-Heffron model of a parallel high voltage alternative current/high voltage direct current(HVAC/HVDC) power system is presented to study power system stability. It is well known that appropriate coupling of inputs-outputs signals in the multivariable HVDC-HVAC system can improve the performance of designed supplemetary controller. In this work, different analysis techniques are used to measure controllability and observability of electromechanical oscillation mode. Also inputs–outputs interactions are considered and suggestions are drawn to select the best signal pair through the system inputs-outputs. In addition, a supplementary online adaptive controller for nonlinear HVDC to damp low frequency oscillations in a weakly connected system is proposed. The results obtained using MATLAB software show that the best output-input for damping controller design is rotor speed deviation as out put and phase angle of rectifier as in put. Also response of system equipped with adaptive damping controller based on HVDC system has appropriate performance when it is faced with faults and disturbance.
文摘Wind energy sources have different structures and functions from conventional power plants in the power system.These resources can affect the exchange of active and reactive power of the network.Therefore,power system stability will be affected by the performance of wind power plants,especially in the event of a fault.In this paper,the improvement of the dynamic stability in power system equipped by wind farm is examined through the supplementary controller design in the high voltage direct current(HVDC)based on voltage source converter(VSC)transmission system.In this regard,impacts of the VSC HVDC system and wind farm on the improvement of system stability are considered.Also,an algorithm based on controllability(observability)concept is proposed to select most appropriate and effective coupling between inputs-outputs(IO)signals of system in different work conditions.The selected coupling is used to apply damping controller signal.Finally,a fractional order PID controller(FO-PID)based on exchange market algorithm(EMA)is designed as damping controller.The analysis of the results shows that the wind farm does not directly contribute to the improvement of the dynamic stability of power system.However,it can increase the controllability of the oscillatory mode and improve the performance of the supplementary controller.
基金the output of a research project (Title: Application of Doubly Fed Asynchronous machine in Pumped Storage Hydropower Plant in Generate Mode, supported by Islamic Azad University South Tehran Branch)
文摘Variable speed pumped storage machines are used extensively in wind power plant and pumped storage power plant. This paper presents direct torque and flux control(DTFC) of a variable speed pumped storage power plant(VSPSP). By this method both torque and flux have been applied to control the VSPSP. The comparison between VSPSP's control strategies is studied. At the first, a wind turbine with the capacity 2.2 k W and DTFC control strategies simulated then a 250 MW VSPSP is simulated with all of its parts(including electrical, mechanical, hydraulic and its control system) by MATLAB software. In all of simulations, both converters including two-level voltage source converter(2LVSC) and three-level voltage source converter(3LVSC) are applied. The results of applying 2LVSC and 3LVSC are the rapid dynamic responses with better efficiency, reducing the total harmonic distortion(THD) and ripple of rotor torque and flux.
文摘三相四桥臂换流器具备不平衡负载工作能力与三相解耦控制功能,已成为主动配电网领域的研究热点。结合三相四桥臂电压源转换器(voltage source converter,VSC)模型,提出一种分相准比例谐振控制(proportion resonant,PR)直接电流控制策略。针对台区首端电流不平衡问题,提出分相功率补偿思路。先设计补偿功率计算策略,再以功率为控制目标计算输入电流参考值,结合分相准比例谐振直接电流控制,对各相进行功率调节,以达到治理三相电流不平衡的目的。在某仿真软件搭建了基于嵌入式低压直流环节(embedded low voltage DC system,E-LVDC)的低压柔性台区模型。仿真结果表明,台区首端三相电流不平衡度降低,从而验证了所提控制策略的有效性。
文摘从实际工程应用出发,建立了单塔双循环湿式烟气脱硫(Single-tower and double-circulation wet flue gas desulfurization,SD-WFGD)系统的控制系统。首先,利用历史运行数据,考虑SD-WFGD系统运行过程吸收塔变频浆液循环泵在不同浆液pH时单位频率变化对烟气SO_(2)浓度的影响,建立了系统动态模型。然后,基于浆液pH脱硫能力提出了直接硫量平衡控制(Direct sulfur balance control,DSC)策略,将已建立的动态模型作为控制模型,并利用传统PID控制器结合DSC策略,建立了SD-WFGD系统串联控制系统。仿真实验结果表明:与传统的PID控制方案相比,所提优化控制方案减小了供浆流量和出口SO_(2)浓度的波动,能够大幅度提升SD-WFGD系统的控制性能,从而更好地保证脱硫系统在燃煤电站灵活运行的背景下安全、稳定、经济及灵活运行。
文摘针对直驱式永磁同步风力发电系统风速多变、非线性和强扰动的问题,提出一种基于模糊控制和线性自抗干扰控制(Linear Active Disturbance Retection Control,LADRC)的混合控制方法。首先对线性自抗扰中的扩张状态观测器(Linear Extended State Observer,LESO)进行改进,提高对扰动观测的能力,同时利用模糊控制动态调整LADRC控制参数,增强系统的抗干扰能力和鲁棒性。仿真结果表明,与传统PI控制器相比,该方法能够更好地估计风速引起的转矩波动,准确跟踪额定转速,实现风能利用最大化。
文摘传统双向E型无线电能传输(wireless power transfer,WPT)拓扑易进入硬开关状态,导致电能传输效率低。针对此,该文提出无线电能传输系统的改进E^(#)型拓扑及其移相控制策略。首先,构建软开关状态负载范围更宽的双向E^(#)型WPT电路拓扑数学模型,分析并提取电路实现软开关工作状态的关键变量与约束条件,理论上证明所提拓扑的有效性。然后,推导电路中线圈互感和负载阻抗等参数的解析关系式,并基于此提出可保证系统在负载时始终处于最佳工作状态的移相控制策略。该策略通过控制开关管的门极驱动信号相位,使谐振元件内部储存的能量提前或者滞后释放,从而将开关管修正回软开关状态。最后,通过仿真和实验验证所提双向E^(#)型WPT系统的有效性。实验结果表明,所提方法可保证在5~30Ω的负载范围内电路工作在软开关状态,该范围内的电能传输效率峰值达84.3%。
