After the North China grid and the Central China grid get into connection with the UHVAC demonstration, a new phenomenon is discovered according to some simulations. That is, the faults at the remote end of the UHV in...After the North China grid and the Central China grid get into connection with the UHVAC demonstration, a new phenomenon is discovered according to some simulations. That is, the faults at the remote end of the UHV interconnected grid will result in significant power fluctuation and voltage drop on the UHV transmission line and even system splitting. But the faults near the UHV line only have marginal effects. Further, the simulation results also indicate that the short-circuit current of the buses near the UHV line is larger than that of the buses far away from the UHV line. This phenomenon is divergent from the traditional view. In this paper, the detail will be introduced, and the factors influencing the system stability after faults are presented and analyzed. The results indicate that transmission power of the UHV line and of the lines between the remote end and the major grid influence the fluctuation on UHV line. The load model and the grid structure of the remote end also have effect on it. Finally, corresponding control scheme is presented to improve the operation conditions of the UHV interconnected grid and ensure its security and stability.展开更多
Due to the development of Distributed Generation (DG), which is installed in Medium-Voltage Distribution Networks (MVDNs) such as generators based on renewable energy (e.g., wind energy or solar energy), voltage contr...Due to the development of Distributed Generation (DG), which is installed in Medium-Voltage Distribution Networks (MVDNs) such as generators based on renewable energy (e.g., wind energy or solar energy), voltage control is currently a very important issue. The voltage is now regulated at the MV busbars acting on the On-Load Tap Changer of the HV/MV transformer. This method does not guarantee the correct voltage value in the network nodes when the distributed generators deliver their power. In this paper an approach based on Sensitivity Theory is shown, in order to control the node voltages regulating the reactive power exchanged between the network and the dispersed generators. The automatic distributed voltage regulation is a particular topic of the Smart Grids.展开更多
针对电网电压不平衡下电流平衡及功率恒定问题,提出改进型光储虚拟同步发电机(virtual synchronous generator,VSG)控制策略,该策略通过引入虚拟阻抗技术和双二阶广义积分器(double second order generalized integrator,DSOGI)实现正...针对电网电压不平衡下电流平衡及功率恒定问题,提出改进型光储虚拟同步发电机(virtual synchronous generator,VSG)控制策略,该策略通过引入虚拟阻抗技术和双二阶广义积分器(double second order generalized integrator,DSOGI)实现正负序分量的有效分离,并基于瞬时功率理论优化电流和功率的协调控制,显著提高了系统在不平衡电网条件下的电流平衡性和功率稳定性。首先,构建基于电机瞬态模型的光伏储能VSG系统的数学模型,以深入理解和模拟VSG在实际电网中的动态行为。通过应用双二阶广义积分器技术,实现了正序与负序分量的有效分离,并基于瞬时功率理论和负序虚拟复阻抗技术,进一步实现电流和功率的协调控制,确保电流平衡及功率恒定。最后,利用MATLA/Simulink软件构建仿真模型,模拟光伏储能系统在不平衡电网状态下的运行情况,仿真结果表明所提控制策略显著提高了控制策略的精度和响应速度,可确保动态电网环境中的操作效率和可靠性。展开更多
文摘After the North China grid and the Central China grid get into connection with the UHVAC demonstration, a new phenomenon is discovered according to some simulations. That is, the faults at the remote end of the UHV interconnected grid will result in significant power fluctuation and voltage drop on the UHV transmission line and even system splitting. But the faults near the UHV line only have marginal effects. Further, the simulation results also indicate that the short-circuit current of the buses near the UHV line is larger than that of the buses far away from the UHV line. This phenomenon is divergent from the traditional view. In this paper, the detail will be introduced, and the factors influencing the system stability after faults are presented and analyzed. The results indicate that transmission power of the UHV line and of the lines between the remote end and the major grid influence the fluctuation on UHV line. The load model and the grid structure of the remote end also have effect on it. Finally, corresponding control scheme is presented to improve the operation conditions of the UHV interconnected grid and ensure its security and stability.
文摘Due to the development of Distributed Generation (DG), which is installed in Medium-Voltage Distribution Networks (MVDNs) such as generators based on renewable energy (e.g., wind energy or solar energy), voltage control is currently a very important issue. The voltage is now regulated at the MV busbars acting on the On-Load Tap Changer of the HV/MV transformer. This method does not guarantee the correct voltage value in the network nodes when the distributed generators deliver their power. In this paper an approach based on Sensitivity Theory is shown, in order to control the node voltages regulating the reactive power exchanged between the network and the dispersed generators. The automatic distributed voltage regulation is a particular topic of the Smart Grids.
文摘针对电网电压不平衡下电流平衡及功率恒定问题,提出改进型光储虚拟同步发电机(virtual synchronous generator,VSG)控制策略,该策略通过引入虚拟阻抗技术和双二阶广义积分器(double second order generalized integrator,DSOGI)实现正负序分量的有效分离,并基于瞬时功率理论优化电流和功率的协调控制,显著提高了系统在不平衡电网条件下的电流平衡性和功率稳定性。首先,构建基于电机瞬态模型的光伏储能VSG系统的数学模型,以深入理解和模拟VSG在实际电网中的动态行为。通过应用双二阶广义积分器技术,实现了正序与负序分量的有效分离,并基于瞬时功率理论和负序虚拟复阻抗技术,进一步实现电流和功率的协调控制,确保电流平衡及功率恒定。最后,利用MATLA/Simulink软件构建仿真模型,模拟光伏储能系统在不平衡电网状态下的运行情况,仿真结果表明所提控制策略显著提高了控制策略的精度和响应速度,可确保动态电网环境中的操作效率和可靠性。
