There are several problems existing in the direct starting of asynchronous motor such as large starting current,reactive power absorption from network side and weak interference-resistance,etc.Aiming at this,a compreh...There are several problems existing in the direct starting of asynchronous motor such as large starting current,reactive power absorption from network side and weak interference-resistance,etc.Aiming at this,a comprehensive energy-saving optimization model of asynchronous motor for voltage regulation based on static synchronous compensator(STATCOM)is put forward.By analyzing the working principle and operation performance of static synchronous compensator regulating voltage,a new energy-efficient optimization method for asynchronous motor is proposed based on the voltage regulator model to achieve soft start,continuous dynamic reactive power compensation and the terminal voltage stability control.The multi-objective optimal operation of asynchronous motor is realized by controlling the inverter to adjust the reactive current dynamically.The strategy reduces the influence of starting current and grid voltage by soft starting,and realizes the function of reactive power compensation and terminal voltage stabilization.The effectiveness and superiority of the proposed model is verified by the simulation analysis and the results of comparison with the motor started directly.展开更多
在弱交流系统下对于附带有STATCOM的电网换相换流器高压直流输电(Line Commutated Converter based High Voltage Direct Current, LCC-HVDC)系统,存在着LCC逆变站与STATCOM之间耦合导致LCC-HVDC系统的稳定裕度下降问题,这会减弱LCC-HVD...在弱交流系统下对于附带有STATCOM的电网换相换流器高压直流输电(Line Commutated Converter based High Voltage Direct Current, LCC-HVDC)系统,存在着LCC逆变站与STATCOM之间耦合导致LCC-HVDC系统的稳定裕度下降问题,这会减弱LCC-HVDC抑制换相失败的能力。此外,HVDC控制环节之中的电压指令电流控制(voltage dependent current order limiter, VDCOL)环节的输出电流指令大幅剧烈波动还有几率会导致HVDC系统在首次换相失败之后发生后续换相失败。针对上述问题提出了一种“改进参考电压”的思想,对STATCOM和VDCOL的参考电压与输入电压分别进行修正。首先在STATCOM原本的参考电压经过一个“虚拟电抗”之后得到一个新的参考电压,通过这个改进参考电压弱化了STATCOM电压外环控制模块与LCC逆变站的耦合,减小了交流系统等效阻抗的大小,提升了系统对干扰的抵抗能力。然后对VDCOL的输入电压进行改进,新的改进输入电压改善了故障后VDCOL输出电流指令的大幅剧烈波动情况。最后通过三个层次的对照试验,验证了所提方法的有效性。展开更多
Conventional proportional integral derivative(PID)controllers are being used in the industries for control purposes.It is very simple in design and low in cost but it has less capability to minimize the low frequency ...Conventional proportional integral derivative(PID)controllers are being used in the industries for control purposes.It is very simple in design and low in cost but it has less capability to minimize the low frequency noises of the systems.Therefore,in this study,a low pass filter has been introduced with the derivative input of the PID controller to minimize the noises and to improve the transient stability of the system.This paper focuses upon the stability improvement of a wind-diesel hybrid power system model(HPSM)using a static synchronous compensator(STATCOM)along with a secondary PID controller with derivative filter(PIDF).Under any load disturbances,the reactive power mismatch occurs in the HPSM that affects the system transient stability.STATCOM with PIDF controller is used to provide reactive power support and to improve stability of the HPSM.The controller parameters are also optimized by using soft computing technique for performance improvement.This paper proposes the effectiveness of symbiosis organisms search algorithm for optimization purpose.Binary coded genetic algorithm and gravitational search algorithm are used for the sake of comparison.展开更多
This paper presents a procedure for designing a supplementary damping stabilizer for a static synchronous series compensator(SSSC) in multi-machine power systems.The objective is to shift the lightly damped inter-area...This paper presents a procedure for designing a supplementary damping stabilizer for a static synchronous series compensator(SSSC) in multi-machine power systems.The objective is to shift the lightly damped inter-area modes toward the prescribed stability region.A lead-lag stabilizer is used to demonstrate this technique,in which a particular measure of stabilizer gain is considered as an objective function.Constraints of the problem for phase-lead and lag structures are derived.The objective function with the constraints is formed as a quadratic mathematical programming problem.For robust design,the parameters of the stabilizer are calculated under various operating conditions.Two types of SSSC-based stabilizer have been presented and designed.Numerical results including eigenvalue analysis and the nonlinear simulations on the 4-and 50-machine power systems are pre-sented to show the effectiveness of the proposed method.展开更多
文摘There are several problems existing in the direct starting of asynchronous motor such as large starting current,reactive power absorption from network side and weak interference-resistance,etc.Aiming at this,a comprehensive energy-saving optimization model of asynchronous motor for voltage regulation based on static synchronous compensator(STATCOM)is put forward.By analyzing the working principle and operation performance of static synchronous compensator regulating voltage,a new energy-efficient optimization method for asynchronous motor is proposed based on the voltage regulator model to achieve soft start,continuous dynamic reactive power compensation and the terminal voltage stability control.The multi-objective optimal operation of asynchronous motor is realized by controlling the inverter to adjust the reactive current dynamically.The strategy reduces the influence of starting current and grid voltage by soft starting,and realizes the function of reactive power compensation and terminal voltage stabilization.The effectiveness and superiority of the proposed model is verified by the simulation analysis and the results of comparison with the motor started directly.
文摘在弱交流系统下对于附带有STATCOM的电网换相换流器高压直流输电(Line Commutated Converter based High Voltage Direct Current, LCC-HVDC)系统,存在着LCC逆变站与STATCOM之间耦合导致LCC-HVDC系统的稳定裕度下降问题,这会减弱LCC-HVDC抑制换相失败的能力。此外,HVDC控制环节之中的电压指令电流控制(voltage dependent current order limiter, VDCOL)环节的输出电流指令大幅剧烈波动还有几率会导致HVDC系统在首次换相失败之后发生后续换相失败。针对上述问题提出了一种“改进参考电压”的思想,对STATCOM和VDCOL的参考电压与输入电压分别进行修正。首先在STATCOM原本的参考电压经过一个“虚拟电抗”之后得到一个新的参考电压,通过这个改进参考电压弱化了STATCOM电压外环控制模块与LCC逆变站的耦合,减小了交流系统等效阻抗的大小,提升了系统对干扰的抵抗能力。然后对VDCOL的输入电压进行改进,新的改进输入电压改善了故障后VDCOL输出电流指令的大幅剧烈波动情况。最后通过三个层次的对照试验,验证了所提方法的有效性。
文摘Conventional proportional integral derivative(PID)controllers are being used in the industries for control purposes.It is very simple in design and low in cost but it has less capability to minimize the low frequency noises of the systems.Therefore,in this study,a low pass filter has been introduced with the derivative input of the PID controller to minimize the noises and to improve the transient stability of the system.This paper focuses upon the stability improvement of a wind-diesel hybrid power system model(HPSM)using a static synchronous compensator(STATCOM)along with a secondary PID controller with derivative filter(PIDF).Under any load disturbances,the reactive power mismatch occurs in the HPSM that affects the system transient stability.STATCOM with PIDF controller is used to provide reactive power support and to improve stability of the HPSM.The controller parameters are also optimized by using soft computing technique for performance improvement.This paper proposes the effectiveness of symbiosis organisms search algorithm for optimization purpose.Binary coded genetic algorithm and gravitational search algorithm are used for the sake of comparison.
文摘This paper presents a procedure for designing a supplementary damping stabilizer for a static synchronous series compensator(SSSC) in multi-machine power systems.The objective is to shift the lightly damped inter-area modes toward the prescribed stability region.A lead-lag stabilizer is used to demonstrate this technique,in which a particular measure of stabilizer gain is considered as an objective function.Constraints of the problem for phase-lead and lag structures are derived.The objective function with the constraints is formed as a quadratic mathematical programming problem.For robust design,the parameters of the stabilizer are calculated under various operating conditions.Two types of SSSC-based stabilizer have been presented and designed.Numerical results including eigenvalue analysis and the nonlinear simulations on the 4-and 50-machine power systems are pre-sented to show the effectiveness of the proposed method.
