This paper addresses the problem of dynamic frequency control in a diesel-based mini-grid. It is shown that a virtual synchronous machine (VSM) can support dynamic frequency control by adding virtual inertia and dampi...This paper addresses the problem of dynamic frequency control in a diesel-based mini-grid. It is shown that a virtual synchronous machine (VSM) can support dynamic frequency control by adding virtual inertia and damping to the system. However, it is found that the typical formulation of damping power does not work properly when the grid forming gen-set operates in droop mode because of the unknown stabilization value of the grid frequency. As a solution to this problem, an estimator for the stabilization frequency that works in conjunction with the damping function of the VSM is proposed. Theoretical and experimental results provide evidence of a satisfactory performance of the proposed VSM with estimator for different values of the gen-set droop factor. The estimated stabilization frequency converges in approximately 2 s and the maximum frequency deviation during the transient is reduced in 34%, on average.展开更多
With photovoltaic(PV)sources becoming more prevalent in the energy generation mix,transitioning grid-connected PV systems from grid-following(GFL)mode to gridforming(GFM)mode becomes essential for offering self-synchr...With photovoltaic(PV)sources becoming more prevalent in the energy generation mix,transitioning grid-connected PV systems from grid-following(GFL)mode to gridforming(GFM)mode becomes essential for offering self-synchronization and active support services.Although numerous GFM methods have been proposed,the potential of DC voltage control malfunction during the provision of the primary and inertia support in a GFM PV system remains insufficiently researched.To fill the gap,some main GFM methods have been integrated into PV systems featuring detailed DC source dynamics.We conduct a comparative analysis of their performance in active support and DC voltage regulation.AC GFM methods such as virtual synchronous machine(VSM)face a significant risk of DC voltage failure in situations like alterations in solar radiation,leading to PV system tripping and jeopardizing local system operation.In the case of DC GFM methods such as matching control(MC),the active support falls short due to the absence of an accurate and dispatchable droop response.To address the issue,a matching synchronous machine(MSM)control method is developed to provide dispatchable active support and enhance the DC voltage dynamics by integrating the MC and VSM control loops.The active support capability of the PV systems with the proposed method is quantified analytically and verified by numerical simulations and field tests.展开更多
This study focuses on a virtual synchronous machine(VSM) based on voltage source converters to mimic the behavior of synchronous machines(SMs) and improve the damping ratio of the power system. The VSM model is simpli...This study focuses on a virtual synchronous machine(VSM) based on voltage source converters to mimic the behavior of synchronous machines(SMs) and improve the damping ratio of the power system. The VSM model is simplified according to some assumptions(neglecting the speed variation and the stator transients) to allow for the possibility of dealing with low-frequency oscillation in large-scale systems with many VSMs. Furthermore, a virtual power system stabilizer(VPSS) structure is proposed and tuned using a method based on a linearized power system dynamic model. The linear and nonlinear analyses examine the stability of two modified versions of a 16-machine power system in which, in the first case, partial classical machines are replaced by VSMs, and in the second case, all SMs are replaced by VSMs. The simulation results of the case studies validate the efficiency of the proposed control strategy.展开更多
现有基于虚拟正弦信号注入(virtual sine signal injection,VSSI)的最大转矩电流比(maximum torque per ampere,MTPA)控制方法以理想永磁同步电动机(permanent magnet synchronous machine,PMSM)数学模型为理论基础,未考虑电感变化带来...现有基于虚拟正弦信号注入(virtual sine signal injection,VSSI)的最大转矩电流比(maximum torque per ampere,MTPA)控制方法以理想永磁同步电动机(permanent magnet synchronous machine,PMSM)数学模型为理论基础,未考虑电感变化带来的不利影响。为了提升MTPA控制效果,增加考虑磁路交叉耦合效应,提出在线电感辨识方法和改进的MTPA控制方法。基于帕德逼近与变步长神经网络的电感辨识方法,不仅可以解决辨识模型欠秩问题,而且能够在线更新变化的电感参数,结合改进的基于VSSI的MTPA控制,可以有效降低电流矢量角误差,减小定子铜损耗,实现更准确的MTPA控制。通过仿真实验对所提方法的准确性进行了验证。展开更多
Due to the absence of inertia, the high proportion of electronic power equipment is a great threat to the stability of the power system. Previous studies have proposed the virtual synchronous machine (VSM) control met...Due to the absence of inertia, the high proportion of electronic power equipment is a great threat to the stability of the power system. Previous studies have proposed the virtual synchronous machine (VSM) control method for the inverter-based distributed generators (DG). However, due to the capacity limitations of DG, the capability of the inverter to provide the inertia action is limited. At the same time, some controllable loads also have the ability to provide inertial support but are still not fully utilised. To get a better grid frequency response, this paper proposes a source-load coordination strategy based on the VSM and virtual asynchronous machine (VAM) concept. For that purpose, a detailed VAM model is firstly derived for the rectifier on power demand side. Not only the virtual inertia and frequency oscillation damping can be provided, but also the syn-chronisation units are not needed to obtain the unknown grid frequency. After that, a distributed consensus-based secondary control is present to regulate the frequency to converge to a reference value based on VSM and VAM. Compared with the existing frequency regulation method, the proposed scheme makes full use of the ability of the load side to participate in frequency modulation. Finally, some numerical simulations are performed to validate the feasibility of the proposed method on MATLAB/Simulink.展开更多
The gradual increase of the penetration rate of new energy connected to the grid leads to the reduction of inertia and damping of the grid,which consequently diminishes the stability of the power system.In response to...The gradual increase of the penetration rate of new energy connected to the grid leads to the reduction of inertia and damping of the grid,which consequently diminishes the stability of the power system.In response to the above problems,this paper proposed an active support grid-connected power generation system based on new energy and permanent generator-motor pairs.Firstly,the basic power generation principle of the motor was introduced,and the damping characteristics of the system were analysed.Then,the multi-mode control method of the system was introduced,including permanent magnet synchronous motor control and grid connection control.The experimental results of the system in actual photovoltaic stations show that this system has functions such as green power generation,frequency support,voltage support and reactive power regulation,which can improve the stability of new energy power generation systems.展开更多
文摘This paper addresses the problem of dynamic frequency control in a diesel-based mini-grid. It is shown that a virtual synchronous machine (VSM) can support dynamic frequency control by adding virtual inertia and damping to the system. However, it is found that the typical formulation of damping power does not work properly when the grid forming gen-set operates in droop mode because of the unknown stabilization value of the grid frequency. As a solution to this problem, an estimator for the stabilization frequency that works in conjunction with the damping function of the VSM is proposed. Theoretical and experimental results provide evidence of a satisfactory performance of the proposed VSM with estimator for different values of the gen-set droop factor. The estimated stabilization frequency converges in approximately 2 s and the maximum frequency deviation during the transient is reduced in 34%, on average.
基金supported in part by the National Key R&D Program of China(No.2022YFB2402900)the National Natural Science Foundation of China(No.U2066601)。
文摘With photovoltaic(PV)sources becoming more prevalent in the energy generation mix,transitioning grid-connected PV systems from grid-following(GFL)mode to gridforming(GFM)mode becomes essential for offering self-synchronization and active support services.Although numerous GFM methods have been proposed,the potential of DC voltage control malfunction during the provision of the primary and inertia support in a GFM PV system remains insufficiently researched.To fill the gap,some main GFM methods have been integrated into PV systems featuring detailed DC source dynamics.We conduct a comparative analysis of their performance in active support and DC voltage regulation.AC GFM methods such as virtual synchronous machine(VSM)face a significant risk of DC voltage failure in situations like alterations in solar radiation,leading to PV system tripping and jeopardizing local system operation.In the case of DC GFM methods such as matching control(MC),the active support falls short due to the absence of an accurate and dispatchable droop response.To address the issue,a matching synchronous machine(MSM)control method is developed to provide dispatchable active support and enhance the DC voltage dynamics by integrating the MC and VSM control loops.The active support capability of the PV systems with the proposed method is quantified analytically and verified by numerical simulations and field tests.
文摘This study focuses on a virtual synchronous machine(VSM) based on voltage source converters to mimic the behavior of synchronous machines(SMs) and improve the damping ratio of the power system. The VSM model is simplified according to some assumptions(neglecting the speed variation and the stator transients) to allow for the possibility of dealing with low-frequency oscillation in large-scale systems with many VSMs. Furthermore, a virtual power system stabilizer(VPSS) structure is proposed and tuned using a method based on a linearized power system dynamic model. The linear and nonlinear analyses examine the stability of two modified versions of a 16-machine power system in which, in the first case, partial classical machines are replaced by VSMs, and in the second case, all SMs are replaced by VSMs. The simulation results of the case studies validate the efficiency of the proposed control strategy.
文摘现有基于虚拟正弦信号注入(virtual sine signal injection,VSSI)的最大转矩电流比(maximum torque per ampere,MTPA)控制方法以理想永磁同步电动机(permanent magnet synchronous machine,PMSM)数学模型为理论基础,未考虑电感变化带来的不利影响。为了提升MTPA控制效果,增加考虑磁路交叉耦合效应,提出在线电感辨识方法和改进的MTPA控制方法。基于帕德逼近与变步长神经网络的电感辨识方法,不仅可以解决辨识模型欠秩问题,而且能够在线更新变化的电感参数,结合改进的基于VSSI的MTPA控制,可以有效降低电流矢量角误差,减小定子铜损耗,实现更准确的MTPA控制。通过仿真实验对所提方法的准确性进行了验证。
基金National Natural Science Foundation of China,Grant/Award Numbers:62073065,U20A20190National Key Research and Development Program of China,Grant/Award Number:2018YFA0702200。
文摘Due to the absence of inertia, the high proportion of electronic power equipment is a great threat to the stability of the power system. Previous studies have proposed the virtual synchronous machine (VSM) control method for the inverter-based distributed generators (DG). However, due to the capacity limitations of DG, the capability of the inverter to provide the inertia action is limited. At the same time, some controllable loads also have the ability to provide inertial support but are still not fully utilised. To get a better grid frequency response, this paper proposes a source-load coordination strategy based on the VSM and virtual asynchronous machine (VAM) concept. For that purpose, a detailed VAM model is firstly derived for the rectifier on power demand side. Not only the virtual inertia and frequency oscillation damping can be provided, but also the syn-chronisation units are not needed to obtain the unknown grid frequency. After that, a distributed consensus-based secondary control is present to regulate the frequency to converge to a reference value based on VSM and VAM. Compared with the existing frequency regulation method, the proposed scheme makes full use of the ability of the load side to participate in frequency modulation. Finally, some numerical simulations are performed to validate the feasibility of the proposed method on MATLAB/Simulink.
文摘The gradual increase of the penetration rate of new energy connected to the grid leads to the reduction of inertia and damping of the grid,which consequently diminishes the stability of the power system.In response to the above problems,this paper proposed an active support grid-connected power generation system based on new energy and permanent generator-motor pairs.Firstly,the basic power generation principle of the motor was introduced,and the damping characteristics of the system were analysed.Then,the multi-mode control method of the system was introduced,including permanent magnet synchronous motor control and grid connection control.The experimental results of the system in actual photovoltaic stations show that this system has functions such as green power generation,frequency support,voltage support and reactive power regulation,which can improve the stability of new energy power generation systems.
