In order to increase the stability of the Mongolia power system, a single-phase automatic reclosing device (SPAR) was introduced on double-circuit power lines built with a size of 330 kV, operating on a voltage of 220...In order to increase the stability of the Mongolia power system, a single-phase automatic reclosing device (SPAR) was introduced on double-circuit power lines built with a size of 330 kV, operating on a voltage of 220 kV and a length of 250 km. These overhead power lines (L-213, L-214) connect the 220/110/35 kV “Songino” substation with the “Mandal” substation and form system networks. This paper presents the challenges encountered when implementing single-phase automatic reclosing (SPAR) devices and compares the changes in power system parameters before and after SPAR deployment for a long 220 kV line. Simulations and analyses were carried out using DIgSILENT PowerFactory software, focusing on rotor angle stability, and the overall impact on the power system during short-circuit faults. The evaluation also utilized measurement data from the Wide Area Monitoring System (WAMS) to compare system behavior pre- and post-implementation of SPAR. The findings reveal that SPAR significantly enhances system reliability and stability, effectively mitigating the risk of oscillations and stability loss triggered by short circuits. This improvement contributes to a more resilient power system, reducing the potential for disturbances caused by faults.展开更多
This paper presents a new concept for damping electro-mechanical oscillations in large turbo generator. The proposed concept is based on coordination between Power System Stabilizer （PSS） and Thyristor Controlled Br...This paper presents a new concept for damping electro-mechanical oscillations in large turbo generator. The proposed concept is based on coordination between Power System Stabilizer （PSS） and Thyristor Controlled Braking Resistor （TCBR）. This coordination will enhance the stability of the inertial and torsional oscillatory modes. The study is performed on system-I of the second IEEE benchmark for simulation of Sub-Synchronous Oscillations, using eigenvalue analysis and verified by detailed digital simulation. A dynamic fundamental frequency model for TCBR is developed. The pole placement technique is used to design the control system of TCBR and PSS. The shaft torque＇s following a disturbance is computed and analyzed. The obtained results indicate that substantial damping is achieved by the proposed coordination.展开更多
A frequency servo system-on-chip(FS-SoC)featuring output power stabilization technology is introduced in this study for high-precision and miniaturized cesium(Cs)atomic clocks.The proposed power stabilization loop(PSL...A frequency servo system-on-chip(FS-SoC)featuring output power stabilization technology is introduced in this study for high-precision and miniaturized cesium(Cs)atomic clocks.The proposed power stabilization loop(PSL)technique,incorporating an off-chip power detector(PD),ensures that the output power of the FS-SoC remains stable,mitigating the impact of power fluctuations on the atomic clock's stability.Additionally,a one-pulse-per-second(1PPS)is employed to syn-chronize the clock with GPS.Fabricated using 65 nm CMOS technology,the measured phase noise of the FS-SoC stands at-69.5 dBc/Hz@100 Hz offset and-83.9 dBc/Hz@1 kHz offset,accompanied by a power dissipation of 19.7 mW.The Cs atomic clock employing the proposed FS-SoC and PSL obtains an Allan deviation of 1.7×10^(-11) with 1-s averaging time.展开更多
A novel technique for the optimal tuning of power system stabilizer (PSS) was proposed,by integrating the modified particle swarm optimization (MPSO) with the chaos (MPSOC).Firstly,a modification in the particle swarm...A novel technique for the optimal tuning of power system stabilizer (PSS) was proposed,by integrating the modified particle swarm optimization (MPSO) with the chaos (MPSOC).Firstly,a modification in the particle swarm optimization (PSO) was made by introducing passive congregation (PC).It helps each swarm member in receiving a multitude of information from other members and thus decreases the possibility of a failed attempt at detection or a meaningless search.Secondly,the MPSO and chaos were hybridized (MPSOC) to improve the global searching capability and prevent the premature convergence due to local minima.The robustness of the proposed PSS tuning technique was verified on a multi-machine power system under different operating conditions.The performance of the proposed MPSOC was compared to the MPSO,PSO and GA through eigenvalue analysis,nonlinear time-domain simulation and statistical tests.Eigenvalue analysis shows acceptable damping of the low-frequency modes and time domain simulations also show that the oscillations of synchronous machines can be rapidly damped for power systems with the proposed PSSs.The results show that the presented algorithm has a faster convergence rate with higher degree of accuracy than the GA,PSO and MPSO.展开更多
为了演示和验证稳定器设计的就地相位补偿法在多机电力系统中的应用,介绍在多机电力系统中,就地补偿设计稳定器的2个应用实例。第1个实例是在多机电力系统中就地补偿设计电力系统稳定器（power system stabilizer,PSS）,阻尼电力系统局...为了演示和验证稳定器设计的就地相位补偿法在多机电力系统中的应用,介绍在多机电力系统中,就地补偿设计稳定器的2个应用实例。第1个实例是在多机电力系统中就地补偿设计电力系统稳定器（power system stabilizer,PSS）,阻尼电力系统局部模振荡。第2个实例是就地补偿设计附加在静态同步补偿器（static synchronous compensator,STATCOM）上的稳定器,抑制多机电力系统中的区域模振荡,并给出在一个16机电力系统中的应用计算和仿真结果。展开更多
The DC microgrid has the advantages of high energy conversion efficiency,high energy transmission density,no reactive power flow,and grid-connected synchronization.It is an essential component of the future intelligen...The DC microgrid has the advantages of high energy conversion efficiency,high energy transmission density,no reactive power flow,and grid-connected synchronization.It is an essential component of the future intelligent power distribution system.Constant power load(CPL)will degrade the stability of the DC microgrid and cause system voltage oscillation due to its negative resistance characteristics.As a result,the stability of DC microgrids with CPL has become a problem.At present,the research on the stability of DC microgrid is mainly focused on unipolar DC microgrid,while the research on bipolar DC microgrid lacks systematic discussion.The stability of DC microgrid using CPL was studied first,and then the current stability criteria of DC microgrid were summarized,and its research trend was analyzed.On this basis,aiming at the stability problem caused by CPL,the existing control methods were summarized from the perspective of source converter output impedance and load converter input impedance,and the current control methods were outlined as active and passive control methods.Lastly,the research path of bipolar DC microgrid stability with CPL was prospected.展开更多
In this paper, Power System Stabilizer (PSS) and Automatic Voltage Regulator (AVR) are coordinated to improve the transient stability of generator in power system. Coordinated design problem of AVR and PSS is formulat...In this paper, Power System Stabilizer (PSS) and Automatic Voltage Regulator (AVR) are coordinated to improve the transient stability of generator in power system. Coordinated design problem of AVR and PSS is formulated as an optimization problem. Particle Swarm Optimization (PSO) technique is an advanced robust search method by the swarming or cooperative behavior of biological populations mechanism. The performance of PSO has been certified in solution of highly non-linear objectives. Thus, PSO technique has been employed to optimize the parameters of PSS and AVR in order to reduce the power system oscillations during the load changing conditions in single-machine, infinite-bus power system. The results of nonlinear simulation suggest that, by coordinated design of AVR and PSS based on PSO technique power system oscillations are exceptionally damped. Correspondingly, it’s shown that power system stability is superiorly enhanced than the uncoordinated designed of the PSS and the AVR controllers.展开更多
Power electronic-interfaced renewable energy sources(RES)exhibit lower inertia compared to traditional synchronous generators.The large-scale integration of RES has led to a significant reduction in system inertia,pos...Power electronic-interfaced renewable energy sources(RES)exhibit lower inertia compared to traditional synchronous generators.The large-scale integration of RES has led to a significant reduction in system inertia,posing significant challenges for maintaining frequency stability in future power systems.This issue has garnered considerable attention in recent years.However,the existing research has not yet achieved a comprehensive understanding of system inertia and frequency stability in the context of low-inertia systems.To this end,this paper provides a comprehensive review of the definition,modeling,analysis,evaluation,and control for frequency stability.It commences with an exploration of inertia and frequency characteristics in low-inertia systems,followed by a novel definition of frequency stability.A summary of frequency stability modeling,analysis,and evaluation methods is then provided,along with their respective applicability in various scenarios.Additionally,the two critical factors of frequency control—energy sources at the system level and control strategies at the device level—are examined.Finally,an outlook on future research in low-inertia power systems is discussed.展开更多
Power system stability is essential for the reliable operation of electrical grids,especially with the increasing integration of renewable energy sources.This paper reviews the types of power system stability-transien...Power system stability is essential for the reliable operation of electrical grids,especially with the increasing integration of renewable energy sources.This paper reviews the types of power system stability-transient,dynamic,voltage,and frequency stability-and explores the challenges posed by renewable energy,such as intermittency and the lack of inertia.The paper also discusses strategies for improving stability,including advanced control techniques,energy storage systems(ESS),demand response,and grid optimization.The integration of these technologies is critical to maintaining grid stability as power systems evolve with greater renewable penetration.展开更多
For solving the dynamic instability problem of Yunnan Provincial Power System (YNPS) and the South China Interconnected Power System (SCIPS), Lubuge Hydropower Station was chosen to install Power System Stabilizer (PS...For solving the dynamic instability problem of Yunnan Provincial Power System (YNPS) and the South China Interconnected Power System (SCIPS), Lubuge Hydropower Station was chosen to install Power System Stabilizer (PSS). This paper introduces the principles and methods of parameter selection for PSS, in addition to field test. The test results show that the PSS installed can significantly improve the system damping.展开更多
In this paper, the Authors present the designing of power system stabilizer (PSS) and static var compensator (SVC) based on chaos, particle swarm optimization (PSO) and shuffled frog leaping (SFL) Algorithms has been ...In this paper, the Authors present the designing of power system stabilizer (PSS) and static var compensator (SVC) based on chaos, particle swarm optimization (PSO) and shuffled frog leaping (SFL) Algorithms has been presented to improve the power system stability. Single machine infinite bus (SMIB) system with SVC located at the terminal of generator has been considered to evaluate the proposed SVC and PSS controllers. The coefficients of PSS and SVC controller have been optimized by Chaos, PSO and SFL algorithms. Fi-nally the system with proposed controllers is simulated for the special disturbance in input power of genera-tor, and then the dynamic responses of generator have been presented. The simulation results show that the system composed with recommended controller has outstanding operation in fast damping of oscillations of power system and describes an application of Chaos, PSO and SFL algorithms to the problem of designing a Lead-Lag controller used in PSS and SVC in power system.展开更多
One method for eliminating oscillations in power systems is using stabilizers.By applying an appropriate control signal in the excitation system of a generator,a power system stabilizer improves the dynamic stability ...One method for eliminating oscillations in power systems is using stabilizers.By applying an appropriate control signal in the excitation system of a generator,a power system stabilizer improves the dynamic stability of power systems.However,the issue that is of high importance is the correct design of these stabilizers.These stabilizers must be designed to have proper performance when operating conditions change.When designed incorrectly,not only they do not improve the stability margin,but also increase the oscillations.In this paper,the robust design of power system stabilizers on a four-machine power system has been performed.For this purpose,the differential evolution algorithm has been used.The studies have been repeated as three scenarios by producing different loading conditions for the generators.The performances of the conventional stabilizer and the optimized one have been compared.Simulation results indicate that the designed robust stabilizer outperforms other stabilizers in different conditions and has damped the interarea and intra-area oscillation modes in the shortest time with minimum amplitude.展开更多
This research paper deals with the identification of the best location of the Power System Stabilizers (PSS) and also the tuning of PSS parameters in order to improve the overall dynamic stability of multi machine pow...This research paper deals with the identification of the best location of the Power System Stabilizers (PSS) and also the tuning of PSS parameters in order to improve the overall dynamic stability of multi machine power systems. The location of PSS is determined by identifying the critical modes and their corresponding first and second order eigenvalue sensitivities. In this formulation, sensitivity analysis of a particular mode can be performed with only its eigenvalues and their left and right eigenvectors. The simplicity and efficiency of this approach sharply contrast to the complexity of the traditional approach, where all eigenvalues and eigenvectors are required at the same time. The effectiveness of this method in selecting the optimum location for placement of PSSs is compared with the participation factor method. The proposed sensitivity theory used to identify the best PSS location in a five machine, eight bus El-Metwally and Malik System to increase the damping of both local and inter area modes for various operating conditions.展开更多
In themarine electric power system,the marine generators will be disturbed by the large change of loads or the fault of the power system.The marine generators usually installed power system stabilizers to damp power s...In themarine electric power system,the marine generators will be disturbed by the large change of loads or the fault of the power system.The marine generators usually installed power system stabilizers to damp power system oscillations through the excitation control.This paper proposes a novel method to obtain optimal parameter values for Power System Stabilizer(PSS)to suppress low-frequency oscillations in the marine electric power system.In this paper,a newly developed immune clone selection algorithm was improved from the three aspects of the adaptive incentive degree,vaccination,and adaptive mutation strategies.Firstly,the typical PSS implementation type of leader-lag structure was adopted and the objective function was set in the optimization process.The performance of PSS tuned by improved immune clone selection algorithm was compared with PSS tuned by basic immune clone selection algorithm(ICSA)under various operating conditions and disturbances.Then,an improved immune clone selection algorithm(IICSA)optimization technique was implemented on two test systems for test purposes.Based on the simulations,it is found that an improved immune clone selection algorithm demonstrates superiority over the basic immune clone selection algorithm in getting a smaller number of iterations and fast convergence rates to achieve the optimal parameters of the power system stabilizers.Moreover,the proposed approach improves the stability and dynamic performance under various loads conditions and disturbances of the marine electric power system.展开更多
In this paper, we examine the problem of designing power system stabilizer (PSS). A new technique is developed using particle swarm optimization (PSO) combined with linear matrix inequality (LMI). The main feature of ...In this paper, we examine the problem of designing power system stabilizer (PSS). A new technique is developed using particle swarm optimization (PSO) combined with linear matrix inequality (LMI). The main feature of PSO, not sticking into a local minimum, is used to eliminate the conservativeness of designing a static output feedback (SOF) stabilizer within an iterative solution of LMIs. The technique is further extended to guarantee robustness against uncertainties wherein power systems operation is changing continuously due to load changes. Numerical simulation ahs illustrated the utility of the developed technique.展开更多
This paper proposes a robust power system stabilizer(PSS)for a steam synchronous generator in Barka II power station.The PSS should be capable of damping small-disturbance oscillations(inherently existing in power sys...This paper proposes a robust power system stabilizer(PSS)for a steam synchronous generator in Barka II power station.The PSS should be capable of damping small-disturbance oscillations(inherently existing in power systems due to e.g.load changes,lines switching...etc.)within a certain settling time for different load conditions.Also,the proposed PSS must have the conventional structure and its parameters must not be violated.To achieve this goal,robust control provides many advantages.The suggested controller is tuned by the Kharitonov’s theorem and uses the standard structure employed in industry.The problem is cast into a nonlinear constrained optimization problem to achieve the desired settling time without violating the practical values of the controller parameters.Performance of the robust PSS is evaluated by several simulations in the presence of system uncertainty due to load changes.展开更多
A method of enhancing power system stability for a single machine to infinite bus power system is presented. The technique used compromises the effectiveness of Proportional-Integral-Derivative controller （PID）. In ...A method of enhancing power system stability for a single machine to infinite bus power system is presented. The technique used compromises the effectiveness of Proportional-Integral-Derivative controller （PID）. In order to satisfy the damping characteristics for the proposed power system over a wide range of operating interval, rotational speed, torque angle and terminal voltage signals of the synchronous machine are utilized as control signals of the system. It is well known that these variables have significant effects on damping the generators shaft mechanical oscillations, it＇ll be so easy to validate the most suitable controller as seen from the simulation results.展开更多
This paper presented PSS （Power system stabilizer） design based on Genetic Algorithm - Fuzzy PID （Proportional Integral and derivative） or GAFPID. GAFPID based PSS design is considered for multimachine power syste...This paper presented PSS （Power system stabilizer） design based on Genetic Algorithm - Fuzzy PID （Proportional Integral and derivative） or GAFPID. GAFPID based PSS design is considered for multimachine power system. The main motivation for this design is to stabilize or to control low-fi＇equency oscillation and terminal voltage of power systems. Genetic Algorithm （GA） is employed for the optimization of the parameter of stabilizer. By minimizing an objective function in which the oscillatory speed deviation of the generator, small signal and large signal performance of the system is improved. The effectiveness of the proposed PSS in increasing the damping of system electromechanical oscillation is demonstrated in a simple two-area power system.展开更多
An lnGaP/GaAs HBT microwave power transistor with on-chip parallel RC stabilization network is developed with a standard GaAs MMIC process. From the stability factor K, the device shows unconditional stability in a wi...An lnGaP/GaAs HBT microwave power transistor with on-chip parallel RC stabilization network is developed with a standard GaAs MMIC process. From the stability factor K, the device shows unconditional stability in a wide frequency range due to the RC network. The power characteristics of the device as measured by a loadpull system show that the large-signal performance of the power transistor is affected slightly by the RC network. Psat is 30dBm at 5.4GHz,and PldB is larger than 21.6dBm at llGHz. The stability of the device due to RC network is proved by a power combination circuit. This makes the power transistor very suitable for applications in microwavc high power ttBT amplifiers.展开更多
文摘In order to increase the stability of the Mongolia power system, a single-phase automatic reclosing device (SPAR) was introduced on double-circuit power lines built with a size of 330 kV, operating on a voltage of 220 kV and a length of 250 km. These overhead power lines (L-213, L-214) connect the 220/110/35 kV “Songino” substation with the “Mandal” substation and form system networks. This paper presents the challenges encountered when implementing single-phase automatic reclosing (SPAR) devices and compares the changes in power system parameters before and after SPAR deployment for a long 220 kV line. Simulations and analyses were carried out using DIgSILENT PowerFactory software, focusing on rotor angle stability, and the overall impact on the power system during short-circuit faults. The evaluation also utilized measurement data from the Wide Area Monitoring System (WAMS) to compare system behavior pre- and post-implementation of SPAR. The findings reveal that SPAR significantly enhances system reliability and stability, effectively mitigating the risk of oscillations and stability loss triggered by short circuits. This improvement contributes to a more resilient power system, reducing the potential for disturbances caused by faults.
文摘This paper presents a new concept for damping electro-mechanical oscillations in large turbo generator. The proposed concept is based on coordination between Power System Stabilizer （PSS） and Thyristor Controlled Braking Resistor （TCBR）. This coordination will enhance the stability of the inertial and torsional oscillatory modes. The study is performed on system-I of the second IEEE benchmark for simulation of Sub-Synchronous Oscillations, using eigenvalue analysis and verified by detailed digital simulation. A dynamic fundamental frequency model for TCBR is developed. The pole placement technique is used to design the control system of TCBR and PSS. The shaft torque＇s following a disturbance is computed and analyzed. The obtained results indicate that substantial damping is achieved by the proposed coordination.
基金supported by the National Natural Science Foundation of China under Grant 62034002 and 62374026.
文摘A frequency servo system-on-chip(FS-SoC)featuring output power stabilization technology is introduced in this study for high-precision and miniaturized cesium(Cs)atomic clocks.The proposed power stabilization loop(PSL)technique,incorporating an off-chip power detector(PD),ensures that the output power of the FS-SoC remains stable,mitigating the impact of power fluctuations on the atomic clock's stability.Additionally,a one-pulse-per-second(1PPS)is employed to syn-chronize the clock with GPS.Fabricated using 65 nm CMOS technology,the measured phase noise of the FS-SoC stands at-69.5 dBc/Hz@100 Hz offset and-83.9 dBc/Hz@1 kHz offset,accompanied by a power dissipation of 19.7 mW.The Cs atomic clock employing the proposed FS-SoC and PSL obtains an Allan deviation of 1.7×10^(-11) with 1-s averaging time.
文摘A novel technique for the optimal tuning of power system stabilizer (PSS) was proposed,by integrating the modified particle swarm optimization (MPSO) with the chaos (MPSOC).Firstly,a modification in the particle swarm optimization (PSO) was made by introducing passive congregation (PC).It helps each swarm member in receiving a multitude of information from other members and thus decreases the possibility of a failed attempt at detection or a meaningless search.Secondly,the MPSO and chaos were hybridized (MPSOC) to improve the global searching capability and prevent the premature convergence due to local minima.The robustness of the proposed PSS tuning technique was verified on a multi-machine power system under different operating conditions.The performance of the proposed MPSOC was compared to the MPSO,PSO and GA through eigenvalue analysis,nonlinear time-domain simulation and statistical tests.Eigenvalue analysis shows acceptable damping of the low-frequency modes and time domain simulations also show that the oscillations of synchronous machines can be rapidly damped for power systems with the proposed PSSs.The results show that the presented algorithm has a faster convergence rate with higher degree of accuracy than the GA,PSO and MPSO.
文摘为了演示和验证稳定器设计的就地相位补偿法在多机电力系统中的应用,介绍在多机电力系统中,就地补偿设计稳定器的2个应用实例。第1个实例是在多机电力系统中就地补偿设计电力系统稳定器（power system stabilizer,PSS）,阻尼电力系统局部模振荡。第2个实例是就地补偿设计附加在静态同步补偿器（static synchronous compensator,STATCOM）上的稳定器,抑制多机电力系统中的区域模振荡,并给出在一个16机电力系统中的应用计算和仿真结果。
基金supported by National Natural Science Foundation of China(No.51767015)Key Project of Natural Science Foundation of Gansu Province(No.22JR5RA317)Tianyou Innovation Team Support Program of Lanzhou Jiaotong University(No.TY202009)。
文摘The DC microgrid has the advantages of high energy conversion efficiency,high energy transmission density,no reactive power flow,and grid-connected synchronization.It is an essential component of the future intelligent power distribution system.Constant power load(CPL)will degrade the stability of the DC microgrid and cause system voltage oscillation due to its negative resistance characteristics.As a result,the stability of DC microgrids with CPL has become a problem.At present,the research on the stability of DC microgrid is mainly focused on unipolar DC microgrid,while the research on bipolar DC microgrid lacks systematic discussion.The stability of DC microgrid using CPL was studied first,and then the current stability criteria of DC microgrid were summarized,and its research trend was analyzed.On this basis,aiming at the stability problem caused by CPL,the existing control methods were summarized from the perspective of source converter output impedance and load converter input impedance,and the current control methods were outlined as active and passive control methods.Lastly,the research path of bipolar DC microgrid stability with CPL was prospected.
文摘In this paper, Power System Stabilizer (PSS) and Automatic Voltage Regulator (AVR) are coordinated to improve the transient stability of generator in power system. Coordinated design problem of AVR and PSS is formulated as an optimization problem. Particle Swarm Optimization (PSO) technique is an advanced robust search method by the swarming or cooperative behavior of biological populations mechanism. The performance of PSO has been certified in solution of highly non-linear objectives. Thus, PSO technique has been employed to optimize the parameters of PSS and AVR in order to reduce the power system oscillations during the load changing conditions in single-machine, infinite-bus power system. The results of nonlinear simulation suggest that, by coordinated design of AVR and PSS based on PSO technique power system oscillations are exceptionally damped. Correspondingly, it’s shown that power system stability is superiorly enhanced than the uncoordinated designed of the PSS and the AVR controllers.
基金supported by the National Natural Science Foundation of China(U2166601)。
文摘Power electronic-interfaced renewable energy sources(RES)exhibit lower inertia compared to traditional synchronous generators.The large-scale integration of RES has led to a significant reduction in system inertia,posing significant challenges for maintaining frequency stability in future power systems.This issue has garnered considerable attention in recent years.However,the existing research has not yet achieved a comprehensive understanding of system inertia and frequency stability in the context of low-inertia systems.To this end,this paper provides a comprehensive review of the definition,modeling,analysis,evaluation,and control for frequency stability.It commences with an exploration of inertia and frequency characteristics in low-inertia systems,followed by a novel definition of frequency stability.A summary of frequency stability modeling,analysis,and evaluation methods is then provided,along with their respective applicability in various scenarios.Additionally,the two critical factors of frequency control—energy sources at the system level and control strategies at the device level—are examined.Finally,an outlook on future research in low-inertia power systems is discussed.
文摘Power system stability is essential for the reliable operation of electrical grids,especially with the increasing integration of renewable energy sources.This paper reviews the types of power system stability-transient,dynamic,voltage,and frequency stability-and explores the challenges posed by renewable energy,such as intermittency and the lack of inertia.The paper also discusses strategies for improving stability,including advanced control techniques,energy storage systems(ESS),demand response,and grid optimization.The integration of these technologies is critical to maintaining grid stability as power systems evolve with greater renewable penetration.
文摘For solving the dynamic instability problem of Yunnan Provincial Power System (YNPS) and the South China Interconnected Power System (SCIPS), Lubuge Hydropower Station was chosen to install Power System Stabilizer (PSS). This paper introduces the principles and methods of parameter selection for PSS, in addition to field test. The test results show that the PSS installed can significantly improve the system damping.
文摘In this paper, the Authors present the designing of power system stabilizer (PSS) and static var compensator (SVC) based on chaos, particle swarm optimization (PSO) and shuffled frog leaping (SFL) Algorithms has been presented to improve the power system stability. Single machine infinite bus (SMIB) system with SVC located at the terminal of generator has been considered to evaluate the proposed SVC and PSS controllers. The coefficients of PSS and SVC controller have been optimized by Chaos, PSO and SFL algorithms. Fi-nally the system with proposed controllers is simulated for the special disturbance in input power of genera-tor, and then the dynamic responses of generator have been presented. The simulation results show that the system composed with recommended controller has outstanding operation in fast damping of oscillations of power system and describes an application of Chaos, PSO and SFL algorithms to the problem of designing a Lead-Lag controller used in PSS and SVC in power system.
文摘One method for eliminating oscillations in power systems is using stabilizers.By applying an appropriate control signal in the excitation system of a generator,a power system stabilizer improves the dynamic stability of power systems.However,the issue that is of high importance is the correct design of these stabilizers.These stabilizers must be designed to have proper performance when operating conditions change.When designed incorrectly,not only they do not improve the stability margin,but also increase the oscillations.In this paper,the robust design of power system stabilizers on a four-machine power system has been performed.For this purpose,the differential evolution algorithm has been used.The studies have been repeated as three scenarios by producing different loading conditions for the generators.The performances of the conventional stabilizer and the optimized one have been compared.Simulation results indicate that the designed robust stabilizer outperforms other stabilizers in different conditions and has damped the interarea and intra-area oscillation modes in the shortest time with minimum amplitude.
文摘This research paper deals with the identification of the best location of the Power System Stabilizers (PSS) and also the tuning of PSS parameters in order to improve the overall dynamic stability of multi machine power systems. The location of PSS is determined by identifying the critical modes and their corresponding first and second order eigenvalue sensitivities. In this formulation, sensitivity analysis of a particular mode can be performed with only its eigenvalues and their left and right eigenvectors. The simplicity and efficiency of this approach sharply contrast to the complexity of the traditional approach, where all eigenvalues and eigenvectors are required at the same time. The effectiveness of this method in selecting the optimum location for placement of PSSs is compared with the participation factor method. The proposed sensitivity theory used to identify the best PSS location in a five machine, eight bus El-Metwally and Malik System to increase the damping of both local and inter area modes for various operating conditions.
基金This work is supported by Shanghai Science and Technology Planning Project(Project No.20040501200).
文摘In themarine electric power system,the marine generators will be disturbed by the large change of loads or the fault of the power system.The marine generators usually installed power system stabilizers to damp power system oscillations through the excitation control.This paper proposes a novel method to obtain optimal parameter values for Power System Stabilizer(PSS)to suppress low-frequency oscillations in the marine electric power system.In this paper,a newly developed immune clone selection algorithm was improved from the three aspects of the adaptive incentive degree,vaccination,and adaptive mutation strategies.Firstly,the typical PSS implementation type of leader-lag structure was adopted and the objective function was set in the optimization process.The performance of PSS tuned by improved immune clone selection algorithm was compared with PSS tuned by basic immune clone selection algorithm(ICSA)under various operating conditions and disturbances.Then,an improved immune clone selection algorithm(IICSA)optimization technique was implemented on two test systems for test purposes.Based on the simulations,it is found that an improved immune clone selection algorithm demonstrates superiority over the basic immune clone selection algorithm in getting a smaller number of iterations and fast convergence rates to achieve the optimal parameters of the power system stabilizers.Moreover,the proposed approach improves the stability and dynamic performance under various loads conditions and disturbances of the marine electric power system.
文摘In this paper, we examine the problem of designing power system stabilizer (PSS). A new technique is developed using particle swarm optimization (PSO) combined with linear matrix inequality (LMI). The main feature of PSO, not sticking into a local minimum, is used to eliminate the conservativeness of designing a static output feedback (SOF) stabilizer within an iterative solution of LMIs. The technique is further extended to guarantee robustness against uncertainties wherein power systems operation is changing continuously due to load changes. Numerical simulation ahs illustrated the utility of the developed technique.
文摘This paper proposes a robust power system stabilizer(PSS)for a steam synchronous generator in Barka II power station.The PSS should be capable of damping small-disturbance oscillations(inherently existing in power systems due to e.g.load changes,lines switching...etc.)within a certain settling time for different load conditions.Also,the proposed PSS must have the conventional structure and its parameters must not be violated.To achieve this goal,robust control provides many advantages.The suggested controller is tuned by the Kharitonov’s theorem and uses the standard structure employed in industry.The problem is cast into a nonlinear constrained optimization problem to achieve the desired settling time without violating the practical values of the controller parameters.Performance of the robust PSS is evaluated by several simulations in the presence of system uncertainty due to load changes.
文摘A method of enhancing power system stability for a single machine to infinite bus power system is presented. The technique used compromises the effectiveness of Proportional-Integral-Derivative controller （PID）. In order to satisfy the damping characteristics for the proposed power system over a wide range of operating interval, rotational speed, torque angle and terminal voltage signals of the synchronous machine are utilized as control signals of the system. It is well known that these variables have significant effects on damping the generators shaft mechanical oscillations, it＇ll be so easy to validate the most suitable controller as seen from the simulation results.
文摘This paper presented PSS （Power system stabilizer） design based on Genetic Algorithm - Fuzzy PID （Proportional Integral and derivative） or GAFPID. GAFPID based PSS design is considered for multimachine power system. The main motivation for this design is to stabilize or to control low-fi＇equency oscillation and terminal voltage of power systems. Genetic Algorithm （GA） is employed for the optimization of the parameter of stabilizer. By minimizing an objective function in which the oscillatory speed deviation of the generator, small signal and large signal performance of the system is improved. The effectiveness of the proposed PSS in increasing the damping of system electromechanical oscillation is demonstrated in a simple two-area power system.
文摘An lnGaP/GaAs HBT microwave power transistor with on-chip parallel RC stabilization network is developed with a standard GaAs MMIC process. From the stability factor K, the device shows unconditional stability in a wide frequency range due to the RC network. The power characteristics of the device as measured by a loadpull system show that the large-signal performance of the power transistor is affected slightly by the RC network. Psat is 30dBm at 5.4GHz,and PldB is larger than 21.6dBm at llGHz. The stability of the device due to RC network is proved by a power combination circuit. This makes the power transistor very suitable for applications in microwavc high power ttBT amplifiers.
