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
The vector control algorithm based on vector space decomposition （VSD） transformation method has a more flexible control freedom, which can control the fundamental and harmonic subspace separately. To this end, a cu...The vector control algorithm based on vector space decomposition （VSD） transformation method has a more flexible control freedom, which can control the fundamental and harmonic subspace separately. To this end, a current vector decoupling control algorithm for six-phase permanent magnet synchronous motor （PMSM） is designed. Using the proposed synchronous rotating coordinate transformation matrix, the fundamental and harmonic components in d-q subspace are changed into direct current （DC） component, only using the traditional proportional integral （PI） controller can meet the non-static difference adjustment, and the controller parameter design method is given by employing intemal model principle. In addition, in order to remove the 5th and 7th harmonic components of stator current, the current PI controller parallel with resonant controller is employed in x-y subspace to realize the specific harmonic component compensation. Simulation results verify the effectiveness of current decoupling vector controller.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
A new type of intelligent recolser controller installed on the outdoor rod is developed, which is mainly composed of microcontroller of Intel 87C196KC 20 and CPLD devices. This controller integrates all the functions ...A new type of intelligent recolser controller installed on the outdoor rod is developed, which is mainly composed of microcontroller of Intel 87C196KC 20 and CPLD devices. This controller integrates all the functions of measuring, controlling, protection, fault diagnosis, communication, remote controlled operation and self power devices with infra red remote control devices as a unit. The controller applies the distributed structure, field concentration line and intelligent technology to seal up the synthetic servomechanisms such as the microcomputer based protection and measuring devices in the second stage of the mini out door transformer substation, which are distributed on the outdoor circuit switches on the spot and formed as a whole. Therefore, this technology can transform a large number of ordinary homemade SF 6 circuit beaker and vacuum circuit breaker into intelligent circuit recloser, thus replacing the expensive imported automatic circuit recolser.展开更多
在光储孤岛直流微电网中,需要最大化利用光伏发电,通常对光伏系统采用最大功率点跟踪(maximum power point tracking, MPPT)技术。但传统的MPPT控制速度慢、精度低,特别是在局部阴影情形下极易陷入局部最优解。基于此,首先提出一种将布...在光储孤岛直流微电网中,需要最大化利用光伏发电,通常对光伏系统采用最大功率点跟踪(maximum power point tracking, MPPT)技术。但传统的MPPT控制速度慢、精度低,特别是在局部阴影情形下极易陷入局部最优解。基于此,首先提出一种将布谷鸟搜索算法与电导增量法相结合的混合MPPT控制。利用布谷鸟搜索算法快速全局寻优,再使用电导增量法精确定位,实现快速而准确地跟踪最大功率点。储能单元是光储直流微电网的重要组成部分,其输出电流均分、荷电状态(stateof charge, SoC)均衡和直流母线电压稳定是主要控制目标。但电流均分受线路电阻差异的影响,进而影响SoC均衡和直流母线电压稳定,于是设计一种新的电压电流双环控制策略以实现上述目标。该策略在电压外环采用母线电压作为反馈值,在电流内环中设计了基于一致性算法的控制策略,将SoC与指数函数结合并引入加速因子,使得在充放电过程中实现SoC的快速均衡。所提控制策略既不需要下垂控制,也无需二次补偿控制,减轻了通信负担。最后在Matlab/Simulink中搭建直流微电网系统模型,验证所设计新的混合MPPT控制和电压电流双环控制策略的有效性。展开更多
研究了板式电涡流阻尼单元(planar eddy current damper,PECD)的阻尼特性随平面振动方向的变化规律。首先,推导了PECD发生相对平移运动时电涡流阻尼力的理论计算公式,发现PECD相对平移运动产生的电涡流阻尼力并不一定与速度方向完全相反...研究了板式电涡流阻尼单元(planar eddy current damper,PECD)的阻尼特性随平面振动方向的变化规律。首先,推导了PECD发生相对平移运动时电涡流阻尼力的理论计算公式,发现PECD相对平移运动产生的电涡流阻尼力并不一定与速度方向完全相反,其在平面直角坐标系上的2个分量可由一个2×2的平面阻尼系数矩阵与相对速度向量的乘积唯一确定。其次,分别选取4种典型永磁阵列的PECD,采用电磁有限元方法计算了它们的平面阻尼系数矩阵和阻尼力随速度方向的变化,验证了上述阻尼力理论计算公式的正确性,并提出了PECD的等效阻尼系数概念。然后,针对等效阻尼系数各向同性的PECD,在保证永磁体高度和投影面积不变的条件下,分析了其阻尼系数随永磁体数量和永磁体行、列间距的变化规律。最后,开展了阻尼系数各向同性PECD的阻尼系数测试试验,进一步验证了理论分析和有限元仿真的正确性。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.
基金Project(51507188)supported by the National Natural Science Foundation of China
文摘The vector control algorithm based on vector space decomposition （VSD） transformation method has a more flexible control freedom, which can control the fundamental and harmonic subspace separately. To this end, a current vector decoupling control algorithm for six-phase permanent magnet synchronous motor （PMSM） is designed. Using the proposed synchronous rotating coordinate transformation matrix, the fundamental and harmonic components in d-q subspace are changed into direct current （DC） component, only using the traditional proportional integral （PI） controller can meet the non-static difference adjustment, and the controller parameter design method is given by employing intemal model principle. In addition, in order to remove the 5th and 7th harmonic components of stator current, the current PI controller parallel with resonant controller is employed in x-y subspace to realize the specific harmonic component compensation. Simulation results verify the effectiveness of current decoupling vector controller.
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.
文摘A new type of intelligent recolser controller installed on the outdoor rod is developed, which is mainly composed of microcontroller of Intel 87C196KC 20 and CPLD devices. This controller integrates all the functions of measuring, controlling, protection, fault diagnosis, communication, remote controlled operation and self power devices with infra red remote control devices as a unit. The controller applies the distributed structure, field concentration line and intelligent technology to seal up the synthetic servomechanisms such as the microcomputer based protection and measuring devices in the second stage of the mini out door transformer substation, which are distributed on the outdoor circuit switches on the spot and formed as a whole. Therefore, this technology can transform a large number of ordinary homemade SF 6 circuit beaker and vacuum circuit breaker into intelligent circuit recloser, thus replacing the expensive imported automatic circuit recolser.
文摘在光储孤岛直流微电网中,需要最大化利用光伏发电,通常对光伏系统采用最大功率点跟踪(maximum power point tracking, MPPT)技术。但传统的MPPT控制速度慢、精度低,特别是在局部阴影情形下极易陷入局部最优解。基于此,首先提出一种将布谷鸟搜索算法与电导增量法相结合的混合MPPT控制。利用布谷鸟搜索算法快速全局寻优,再使用电导增量法精确定位,实现快速而准确地跟踪最大功率点。储能单元是光储直流微电网的重要组成部分,其输出电流均分、荷电状态(stateof charge, SoC)均衡和直流母线电压稳定是主要控制目标。但电流均分受线路电阻差异的影响,进而影响SoC均衡和直流母线电压稳定,于是设计一种新的电压电流双环控制策略以实现上述目标。该策略在电压外环采用母线电压作为反馈值,在电流内环中设计了基于一致性算法的控制策略,将SoC与指数函数结合并引入加速因子,使得在充放电过程中实现SoC的快速均衡。所提控制策略既不需要下垂控制,也无需二次补偿控制,减轻了通信负担。最后在Matlab/Simulink中搭建直流微电网系统模型,验证所设计新的混合MPPT控制和电压电流双环控制策略的有效性。
文摘研究了板式电涡流阻尼单元(planar eddy current damper,PECD)的阻尼特性随平面振动方向的变化规律。首先,推导了PECD发生相对平移运动时电涡流阻尼力的理论计算公式,发现PECD相对平移运动产生的电涡流阻尼力并不一定与速度方向完全相反,其在平面直角坐标系上的2个分量可由一个2×2的平面阻尼系数矩阵与相对速度向量的乘积唯一确定。其次,分别选取4种典型永磁阵列的PECD,采用电磁有限元方法计算了它们的平面阻尼系数矩阵和阻尼力随速度方向的变化,验证了上述阻尼力理论计算公式的正确性,并提出了PECD的等效阻尼系数概念。然后,针对等效阻尼系数各向同性的PECD,在保证永磁体高度和投影面积不变的条件下,分析了其阻尼系数随永磁体数量和永磁体行、列间距的变化规律。最后,开展了阻尼系数各向同性PECD的阻尼系数测试试验,进一步验证了理论分析和有限元仿真的正确性。
