With the increasing integration of renewable energy,microgrids are increasingly facing stability challenges,primarily due to the lack of inherent inertia in inverter-dominated systems,which is traditionally provided b...With the increasing integration of renewable energy,microgrids are increasingly facing stability challenges,primarily due to the lack of inherent inertia in inverter-dominated systems,which is traditionally provided by synchronous generators.To address this critical issue,Virtual Synchronous Generator(VSG)technology has emerged as a highly promising solution by emulating the inertia and damping characteristics of conventional synchronous generators.To enhance the operational efficiency of virtual synchronous generators(VSGs),this study employs smallsignal modeling analysis,root locus methods,and synchronous generator power-angle characteristic analysis to comprehensively evaluate how virtual inertia and damping coefficients affect frequency stability and power output during transient processes.Based on these analyses,an adaptive control strategy is proposed:increasing the virtual inertia when the rotor angular velocity undergoes rapid changes,while strengthening the damping coefficient when the speed deviation exceeds a certain threshold to suppress angular velocity oscillations.To validate the effectiveness of the proposed method,a grid-connected VSG simulation platform was developed inMATLAB/Simulink.Comparative simulations demonstrate that the proposed adaptive control strategy outperforms conventional VSGmethods by significantly reducing grid frequency deviations and shortening active power response time during active power command changes and load disturbances.This approach enhances microgrid stability and dynamic performance,confirming its viability for renewable-dominant power systems.Future work should focus on experimental validation and real-world parameter optimization,while further exploring the strategy’s effectiveness in improvingVSG low-voltage ride-through(LVRT)capability and power-sharing applications in multi-parallel configurations.展开更多
This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial...This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial and resonant disturbances.In this estimator structure,referred to as Cascade GPIO(CGPIO),the total disturbance sensitivity is the product of the sensitivities at each cascade level.This approach improves system performance against both periodic and non-periodic disturbances and enhances robustness under frequency variations in harmonic components.Additionally,the decoupled nature of the estimator reduces the order of the GPIOs,thereby simplifying tuning and limiting observer gains.The proposed control scheme is supported by a frequency-domain analysis and is experimentally validated in the current control of a grid-connected converter subject to control gain uncertainties,harmonic distortion,frequency deviations,and measurement noise.Experimental results demonstrate that the CGPIO-based ADRC outperforms benchmark solutions,including proportional-integral(PI)and proportional-resonant(PR)controllers.展开更多
This paper presents an investigation on a voltage and frequency controller (VFC), which functions as an improved elec-tronic load controller (IELC) for parallel operated isolated asynchronous generators (IAGs) in an a...This paper presents an investigation on a voltage and frequency controller (VFC), which functions as an improved elec-tronic load controller (IELC) for parallel operated isolated asynchronous generators (IAGs) in an autonomous hydro power generation system. In such type of hydro scheme whole generating system is isolated from the grid and supply electricity to the remote communities. The single point operation of these generators is realized, in such a manner that excitation capacitors, speeds, load, voltage, currents of generators remain constant under various operating conditions. The proposed controller consists of a 3-leg IGBT (Insulated Gate Bipolar Transistor) based voltage source converter (VSC) and a DC chopper with an auxiliary load at the DC bus of the VSC. The IELC controls the reactive and active powers simultaneously for controlling the voltage and frequency under varying consumer loads. Along with voltage and frequency control through single point operation of IAGs driven by uncontrolled pico hydro turbines, the IELC meets the power quality standard an IEEE-519 and it keeps the total harmonic distortion (THD) of the terminal voltage and currents within the limit of 5%. Here the proposed electrical system along with its controller is modeled in MATLAB along with Simulink and PSB (Power System Block-set) toolboxes. Simulation results are presented to demonstrate the capability of proposed controller for an isolated generating system.展开更多
This paper investigates the function of doubly-fed asynchronous machine(DASM)with emphasis placed on its ability to the stabilization of the power system including wind generators.P(active power)and Q(reactive power)c...This paper investigates the function of doubly-fed asynchronous machine(DASM)with emphasis placed on its ability to the stabilization of the power system including wind generators.P(active power)and Q(reactive power)compensation from DASM can be regulated independently through secondary-excitation controlling.Simulation results by power system computer aided design(PSCAD)show that DASM can restore the wind-generator system to a normal operating condition rapidly even following severe transmission-line failures.Comparison studies have also been performed between wind turbine pitch control and proposed method.展开更多
对2007年版《IEEE Guide for AC Generator Protection》中失磁保护定值整定的几个问题提出不同意见。明确指出:发电机失磁故障必有滑差(s),其平均异步阻抗Xd(js)Xd(s=0),失磁保护中的阻抗元件下端定值为-Xd,已有足够余度,不应该是-(1.1...对2007年版《IEEE Guide for AC Generator Protection》中失磁保护定值整定的几个问题提出不同意见。明确指出:发电机失磁故障必有滑差(s),其平均异步阻抗Xd(js)Xd(s=0),失磁保护中的阻抗元件下端定值为-Xd,已有足够余度,不应该是-(1.1～1.25)Xd;在P-Q坐标与R-X坐标的转换公式中,U值应由"失磁保护动作滞后于低励限制线(UEL)"原则来确定,不应主观选择0.95UN。展开更多
In this paper, we present the steady state analysis of a double-fed induction generator (DFIG) adopted for wind power generation. The three-phase induction machine connected to the network, to work as a generator for ...In this paper, we present the steady state analysis of a double-fed induction generator (DFIG) adopted for wind power generation. The three-phase induction machine connected to the network, to work as a generator for wind farms, is excited on the rotor circuit by a slip-frequency current injected to the rotor, from an exciter mounted on the same shaft of the machine. The resulting rotating magnetic field rotates at synchronous speed;as such the generated power has a constant frequency independent of the shaft speed. Effects of the excitation voltage magnitude and phase angle on the active and reactive power are studied, when the machine runs at constant speed. It has been shown that by controlling the excitation voltage magnitude and phase angle would control the mode of operation of the machine;motor mode or generator mode. Furthermore, the effects of the shaft speed on the active and reactive power at constant excitation voltage magnitude and constant phase angle are also investigated.展开更多
This paper analyses the synchronization problem of a generator onto power system without satisfying synchronization condition. The main focus of the paper is on the impact of the dc component of the current in the hig...This paper analyses the synchronization problem of a generator onto power system without satisfying synchronization condition. The main focus of the paper is on the impact of the dc component of the current in the high voltage circuit breaker during its close-open operating cycle. Using real time measurements of currents/voltages and angles during the close-opening cycle of high voltage generator circuit breaker and the impact of the dc component of current in context of interrupting large magnitude of current from the circuit breaker. In addition, the paper describes a study case model and the results of simulations performed using the software EMTP-ATP of an actual incident that occurred during the inadvertent synchronization of a large 339 MW, 24 kV generator to the grid.展开更多
Dynamic equivalence of the wind farm is a fundamental problem in the simulation of a power system connected with wind farms because it is unpractical to model every generator in a wind farm in detail. In this paper, a...Dynamic equivalence of the wind farm is a fundamental problem in the simulation of a power system connected with wind farms because it is unpractical to model every generator in a wind farm in detail. In this paper, an Equivalence Method based on the Output Characteristics (EMOC) is proposed, with which the wind farm composed of Squirrel-Cage Induction Generators (SCIGs) can be equivalent to one generator. By considering the diversity of wind generators and special operating characteristics of a wind farm, the equivalent generator based on EMOC responds accurately in various faults. No matter whether the wind farm is integrated in grid or just programmed, EMOC can be used to acquire an accurate equivalent generator. Simulation of the dynamic equivalence of an SCIG wind farm validated the method.展开更多
This paper proposes a tube-based method for the asynchronous observation problem of discrete-time switched linear systems in the presence of amplitude-bounded disturbances.Sufficient stability conditions of the nomina...This paper proposes a tube-based method for the asynchronous observation problem of discrete-time switched linear systems in the presence of amplitude-bounded disturbances.Sufficient stability conditions of the nominal observer error system under mode-dependent persistent dwell-time(MPDT)switching are first established. Taking the disturbances into account, a novel asynchronous MPDT robust positive invariant(RPI) set and an asynchronous MPDT generalized RPI(GRPI)set are determined for the difference system between the nominal and disturbed observer error systems. Further, the global uniform asymptotical stability of the observer error system is established in the sense of converging to the asynchronous MPDT GRPI set, i.e., the cross section of the tube of the observer error system. Finally, the proposed results are validated on a space robot manipulator example.展开更多
In this paper modelling and analysis in autonomous mode of dual three-phase induction generator (DTPIG) with a new algorithm have been done. We develop the steady state model of a dual three-phase self-excited inducti...In this paper modelling and analysis in autonomous mode of dual three-phase induction generator (DTPIG) with a new algorithm have been done. We develop the steady state model of a dual three-phase self-excited induction generator for stand-alone renewable generation dispensing with the segregating real and imaginary components of the complex impedance of the induction generator. The obtained admittance yields the adequate magnetizing reactance and the frequency. These two key parameters are then used to compute the self-excitation process requirements in terms of the prime mover speed, the capacitance and the load impedance on the one hand and to predict the generator steady state performance parameters on the other. Steady state performances and characteristics of different configurations are clearly examined and compared. The analytical results are found to be in good agreement with experimental results.展开更多
基金financially supported by the Talent Initiation Fund of Wuxi University(550220008).
文摘With the increasing integration of renewable energy,microgrids are increasingly facing stability challenges,primarily due to the lack of inherent inertia in inverter-dominated systems,which is traditionally provided by synchronous generators.To address this critical issue,Virtual Synchronous Generator(VSG)technology has emerged as a highly promising solution by emulating the inertia and damping characteristics of conventional synchronous generators.To enhance the operational efficiency of virtual synchronous generators(VSGs),this study employs smallsignal modeling analysis,root locus methods,and synchronous generator power-angle characteristic analysis to comprehensively evaluate how virtual inertia and damping coefficients affect frequency stability and power output during transient processes.Based on these analyses,an adaptive control strategy is proposed:increasing the virtual inertia when the rotor angular velocity undergoes rapid changes,while strengthening the damping coefficient when the speed deviation exceeds a certain threshold to suppress angular velocity oscillations.To validate the effectiveness of the proposed method,a grid-connected VSG simulation platform was developed inMATLAB/Simulink.Comparative simulations demonstrate that the proposed adaptive control strategy outperforms conventional VSGmethods by significantly reducing grid frequency deviations and shortening active power response time during active power command changes and load disturbances.This approach enhances microgrid stability and dynamic performance,confirming its viability for renewable-dominant power systems.Future work should focus on experimental validation and real-world parameter optimization,while further exploring the strategy’s effectiveness in improvingVSG low-voltage ride-through(LVRT)capability and power-sharing applications in multi-parallel configurations.
文摘This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial and resonant disturbances.In this estimator structure,referred to as Cascade GPIO(CGPIO),the total disturbance sensitivity is the product of the sensitivities at each cascade level.This approach improves system performance against both periodic and non-periodic disturbances and enhances robustness under frequency variations in harmonic components.Additionally,the decoupled nature of the estimator reduces the order of the GPIOs,thereby simplifying tuning and limiting observer gains.The proposed control scheme is supported by a frequency-domain analysis and is experimentally validated in the current control of a grid-connected converter subject to control gain uncertainties,harmonic distortion,frequency deviations,and measurement noise.Experimental results demonstrate that the CGPIO-based ADRC outperforms benchmark solutions,including proportional-integral(PI)and proportional-resonant(PR)controllers.
文摘This paper presents an investigation on a voltage and frequency controller (VFC), which functions as an improved elec-tronic load controller (IELC) for parallel operated isolated asynchronous generators (IAGs) in an autonomous hydro power generation system. In such type of hydro scheme whole generating system is isolated from the grid and supply electricity to the remote communities. The single point operation of these generators is realized, in such a manner that excitation capacitors, speeds, load, voltage, currents of generators remain constant under various operating conditions. The proposed controller consists of a 3-leg IGBT (Insulated Gate Bipolar Transistor) based voltage source converter (VSC) and a DC chopper with an auxiliary load at the DC bus of the VSC. The IELC controls the reactive and active powers simultaneously for controlling the voltage and frequency under varying consumer loads. Along with voltage and frequency control through single point operation of IAGs driven by uncontrolled pico hydro turbines, the IELC meets the power quality standard an IEEE-519 and it keeps the total harmonic distortion (THD) of the terminal voltage and currents within the limit of 5%. Here the proposed electrical system along with its controller is modeled in MATLAB along with Simulink and PSB (Power System Block-set) toolboxes. Simulation results are presented to demonstrate the capability of proposed controller for an isolated generating system.
文摘This paper investigates the function of doubly-fed asynchronous machine(DASM)with emphasis placed on its ability to the stabilization of the power system including wind generators.P(active power)and Q(reactive power)compensation from DASM can be regulated independently through secondary-excitation controlling.Simulation results by power system computer aided design(PSCAD)show that DASM can restore the wind-generator system to a normal operating condition rapidly even following severe transmission-line failures.Comparison studies have also been performed between wind turbine pitch control and proposed method.
文摘对2007年版《IEEE Guide for AC Generator Protection》中失磁保护定值整定的几个问题提出不同意见。明确指出:发电机失磁故障必有滑差(s),其平均异步阻抗Xd(js)Xd(s=0),失磁保护中的阻抗元件下端定值为-Xd,已有足够余度,不应该是-(1.1～1.25)Xd;在P-Q坐标与R-X坐标的转换公式中,U值应由"失磁保护动作滞后于低励限制线(UEL)"原则来确定,不应主观选择0.95UN。
文摘In this paper, we present the steady state analysis of a double-fed induction generator (DFIG) adopted for wind power generation. The three-phase induction machine connected to the network, to work as a generator for wind farms, is excited on the rotor circuit by a slip-frequency current injected to the rotor, from an exciter mounted on the same shaft of the machine. The resulting rotating magnetic field rotates at synchronous speed;as such the generated power has a constant frequency independent of the shaft speed. Effects of the excitation voltage magnitude and phase angle on the active and reactive power are studied, when the machine runs at constant speed. It has been shown that by controlling the excitation voltage magnitude and phase angle would control the mode of operation of the machine;motor mode or generator mode. Furthermore, the effects of the shaft speed on the active and reactive power at constant excitation voltage magnitude and constant phase angle are also investigated.
文摘This paper analyses the synchronization problem of a generator onto power system without satisfying synchronization condition. The main focus of the paper is on the impact of the dc component of the current in the high voltage circuit breaker during its close-open operating cycle. Using real time measurements of currents/voltages and angles during the close-opening cycle of high voltage generator circuit breaker and the impact of the dc component of current in context of interrupting large magnitude of current from the circuit breaker. In addition, the paper describes a study case model and the results of simulations performed using the software EMTP-ATP of an actual incident that occurred during the inadvertent synchronization of a large 339 MW, 24 kV generator to the grid.
文摘Dynamic equivalence of the wind farm is a fundamental problem in the simulation of a power system connected with wind farms because it is unpractical to model every generator in a wind farm in detail. In this paper, an Equivalence Method based on the Output Characteristics (EMOC) is proposed, with which the wind farm composed of Squirrel-Cage Induction Generators (SCIGs) can be equivalent to one generator. By considering the diversity of wind generators and special operating characteristics of a wind farm, the equivalent generator based on EMOC responds accurately in various faults. No matter whether the wind farm is integrated in grid or just programmed, EMOC can be used to acquire an accurate equivalent generator. Simulation of the dynamic equivalence of an SCIG wind farm validated the method.
基金supported in part by the National Defense Basic Scientific Research Program of China(JCKY2018603C015)Cultivation Plan of Major Research Program of Harbin Institute of Technology(ZDXMPY20180101)
文摘This paper proposes a tube-based method for the asynchronous observation problem of discrete-time switched linear systems in the presence of amplitude-bounded disturbances.Sufficient stability conditions of the nominal observer error system under mode-dependent persistent dwell-time(MPDT)switching are first established. Taking the disturbances into account, a novel asynchronous MPDT robust positive invariant(RPI) set and an asynchronous MPDT generalized RPI(GRPI)set are determined for the difference system between the nominal and disturbed observer error systems. Further, the global uniform asymptotical stability of the observer error system is established in the sense of converging to the asynchronous MPDT GRPI set, i.e., the cross section of the tube of the observer error system. Finally, the proposed results are validated on a space robot manipulator example.
文摘In this paper modelling and analysis in autonomous mode of dual three-phase induction generator (DTPIG) with a new algorithm have been done. We develop the steady state model of a dual three-phase self-excited induction generator for stand-alone renewable generation dispensing with the segregating real and imaginary components of the complex impedance of the induction generator. The obtained admittance yields the adequate magnetizing reactance and the frequency. These two key parameters are then used to compute the self-excitation process requirements in terms of the prime mover speed, the capacitance and the load impedance on the one hand and to predict the generator steady state performance parameters on the other. Steady state performances and characteristics of different configurations are clearly examined and compared. The analytical results are found to be in good agreement with experimental results.
